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{{Short description|Interruption of cardiac blood supply}}
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{{redirect|Heart attack}} {{Redirect|Heart attack}}
{{Distinguish|cardiac arrest|heart failure|heart block}}

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{{Infobox_Disease |
].]]
Name = Myocardial infarction|
{{Cs1 config|name-list-style=vanc}}
Image = AMI scheme.png |
{{Good article}}
Caption = Diagram of a '''myocardial infarction''' (2) of the tip of the ] (an ''apical infarct'') after occlusion (1) of a branch of the ] (LCA, ] = RCA).|
{{Infobox medical condition
DiseasesDB = 8664 |
| name = Myocardial infarction
ICD10 = {{ICD10|I|21||i|20}}-{{ICD10|I|22||i|20}} |
| synonyms = Acute myocardial infarction (AMI), heart attack
ICD9 = {{ICD9|410}} |
ICDO = | | image = Blausen 0463 HeartAttack.png
| caption = A myocardial infarction occurs when an ] ] slowly builds up in the inner lining of a ] and then suddenly ruptures, causing catastrophic ] formation, totally occluding the artery and preventing blood flow downstream to the heart muscle.
OMIM = |
| field = ], ]
MedlinePlus = 000195 |
| symptoms = ], ], ]/], ] or ], ], ]; arm, neck, back, jaw, or stomach pain,<ref name=HLB2014 /><ref>{{cite web|url=https://www.heart.org/en/health-topics/heart-attack/warning-signs-of-a-heart-attack/heart-attack-symptoms-in-women|title=Heart Attack Symptoms in Women|website=American Heart Association}}</ref> ] or ]
eMedicineSubj = med |
| complications = ], ], ], ], ]<ref name=HLB2013MI /><ref name=Heart2015 />
eMedicineTopic = 1567 |
| onset =
eMedicine_mult = {{eMedicine2|emerg|327}} {{eMedicine2|ped|2520}} |
MeshID = D009203 | | duration =
| causes = ] or ] usually<ref name=HLB2013MI />
| risks = ], ], ], ], ], ]<ref name=Meh2014 /><ref name=WHO2011 />
| diagnosis = ]s (ECGs), blood tests, ]<ref name=HLB2013D />
| differential =
| prevention =
| treatment = ], ]<ref name=Europe2012 />
| medication = ], ], ]<ref name=Europe2012 /><ref name=Oc2010 />
| prognosis = STEMI 10% risk of death (developed world)<ref name=Europe2012 />
| frequency = 15.9 million (2015)<ref name=GBD2015Pre />
| deaths =
}} }}


<!-- Definition and symptoms -->
'''Myocardial infarction''' ('''MI''' or '''AMI''' for '''acute myocardial infarction'''), commonly known as a '''heart attack''', occurs when the ] to part of the ] is interrupted. This is most commonly due to occlusion (blockage) of a ] following the rupture of a ], which is an unstable collection of ] (like ]) and ]s (especially ]s) in the wall of an ]. The resulting ] (restriction in blood supply) and ], if left untreated for a sufficient period, can cause damage and/or death ('']'') of heart muscle tissue ('']'').
A '''myocardial infarction''' ('''MI'''), commonly known as a '''heart attack''', occurs when ] or stops in one of the ] of the ], causing ] (tissue death) to the ].<ref name=HLB2014 /> The most common symptom is retrosternal ] that classically radiates to the left shoulder, arm, or jaw.<ref name=HLB2014 /> The pain may occasionally feel like ].<ref name=HLB2014 /> This is the dangerous type of ].


Other symptoms may include ], ], ], a ], ], and ].<ref name="HLB2014">{{cite web|title=What Are the Signs and Symptoms of Coronary Heart Disease?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/cad/signs|website=www.nhlbi.nih.gov|access-date=23 February 2015|date=September 29, 2014|url-status=dead|archive-url=https://web.archive.org/web/20150224034615/http://www.nhlbi.nih.gov/health/health-topics/topics/cad/signs|archive-date=24 February 2015}}</ref> About 30% of people have atypical symptoms.<ref name="Europe2012" /> Women more often present without chest pain and instead have neck pain, arm pain or feel tired.<ref>{{cite journal | vauthors = Coventry LL, Finn J, Bremner AP | title = Sex differences in symptom presentation in acute myocardial infarction: a systematic review and meta-analysis | journal = Heart & Lung | volume = 40 | issue = 6 | pages = 477–91 | date = 2011 | pmid = 22000678 | doi = 10.1016/j.hrtlng.2011.05.001 }}</ref> Among those over 75 years old, about 5% have had an MI with little or no history of symptoms.<ref name="Val2011">{{cite journal | vauthors = Valensi P, Lorgis L, Cottin Y | title = Prevalence, incidence, predictive factors and prognosis of silent myocardial infarction: a review of the literature | journal = Archives of Cardiovascular Diseases | volume = 104 | issue = 3 | pages = 178–88 | date = March 2011 | pmid = 21497307 | doi = 10.1016/j.acvd.2010.11.013 | doi-access = free }}</ref> An MI may cause ], an ], ] or ].<ref name=HLB2013MI /><ref name=Heart2015>{{cite web|title=Heart Attack or Sudden Cardiac Arrest: How Are They Different?|url=http://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/Heart-Attack-or-Sudden-Cardiac-Arrest-How-Are-They-Different_UCM_440804_Article.jsp|website=www.heart.org|access-date=24 February 2015|date=Jul 30, 2014|url-status=live|archive-url=https://web.archive.org/web/20150224045054/http://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/Heart-Attack-or-Sudden-Cardiac-Arrest-How-Are-They-Different_UCM_440804_Article.jsp|archive-date=24 February 2015}}</ref>
Classical symptoms of acute myocardial infarction include sudden ] (typically radiating to the left arm or left side of the neck), ], ], ], ]s, ], and ] (often described as a sense of impending doom). Women may experience fewer typical symptoms than men, most commonly shortness of breath, weakness, a feeling of indigestion, and ].<ref name="Kosuge">{{cite journal | last=Kosuge | first=M | coauthors= Kimura K, Ishikawa T et al. | title=Differences between men and women in terms of clinical features of ST-segment elevation acute myocardial infarction | journal=Circulation Journal | volume=70 | issue=3 | pages=222–226 | date=March 2006 | pmid=16501283 | url=http://www.jstage.jst.go.jp/article/circj/70/3/222/_pdf | accessdate=2008-05-31 | doi=10.1253/circj.70.222 }}</ref> Approximately one quarter of all myocardial infarctions are silent, without chest pain or other symptoms. A heart attack is a ], and people experiencing chest pain are advised to alert their ], because prompt treatment is beneficial.


<!--Mechanism & Diagnosis -->
Heart attacks are the leading cause of death for both men and women all over the world.<ref name="WHO-2002">{{cite book | authorlink=http://www.who.int/en/ | title=The World Health Report 2004 - Changing History | publisher=] | date=2004 | pages=120–4 | format=PDF | url=http://www.who.int/entity/whr/2004/en/report04_en.pdf | isbn= 92-4-156265-X}}</ref> Important ]s are previous ] (such as ], a previous heart attack or ]), older age (especially men over 40 and women over 50), ], high blood levels of certain lipids (]s, ] or "bad cholesterol") and low ] (HDL, "good cholesterol"), ], ], ], ], ], ], the abuse of certain drugs (such as ]), and chronic high stress levels.<ref name="pmid18241872">{{cite journal |author=Bax L, Algra A, Mali WP, Edlinger M, Beutler JJ, van der Graaf Y |title=Renal function as a risk indicator for cardiovascular events in 3216 patients with manifest arterial disease |journal=Atherosclerosis |volume= |issue= |pages= |year=2008 |pmid=18241872 |doi=10.1016/j.atherosclerosis.2007.12.006 |url=http://linkinghub.elsevier.com/retrieve/pii/S0021-9150(07)00768-X}}</ref><ref name="pmid16651468">{{cite journal |author=Pearte CA, Furberg CD, O'Meara ES, ''et al'' |title=Characteristics and baseline clinical predictors of future fatal versus nonfatal coronary heart disease events in older adults: the Cardiovascular Health Study |journal=Circulation |volume=113 |issue=18 |pages=2177–85 |year=2006 |pmid=16651468 |doi=10.1161/CIRCULATIONAHA.105.610352 |url=http://circ.ahajournals.org/cgi/content/full/113/18/2177}}</ref>
Most MIs occur due to ].<ref name=HLB2013MI>{{cite web|title=What Is a Heart Attack?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/|website=www.nhlbi.nih.gov|access-date=24 February 2015|date=December 17, 2013|url-status=live|archive-url=https://web.archive.org/web/20150219152830/http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/|archive-date=19 February 2015}}</ref> Risk factors include ], ], ], ], ], ], poor diet, and ].<ref name=Meh2014>{{cite journal | vauthors = Mehta PK, Wei J, Wenger NK | title = Ischemic heart disease in women: a focus on risk factors | journal = Trends in Cardiovascular Medicine | volume = 25 | issue = 2 | pages = 140–51 | date = February 2015 | pmid = 25453985 | pmc = 4336825 | doi = 10.1016/j.tcm.2014.10.005 }}</ref><ref name=WHO2011>{{cite book | vauthors = Mendis S, Puska P, Norrving B |title=Global atlas on cardiovascular disease prevention and control |date=2011 |publisher=World Health Organization in collaboration with the World Heart Federation and the World Stroke Organization |location=Geneva |isbn=978-92-4-156437-3 |pages=3–18 |edition=1st |url=http://whqlibdoc.who.int/publications/2011/9789241564373_eng.pdf?ua=1 |url-status=live|archive-url= https://web.archive.org/web/20140817123106/http://whqlibdoc.who.int/publications/2011/9789241564373_eng.pdf?ua=1 |archive-date=2014-08-17 }}</ref> The complete blockage of a ] caused by a rupture of an ] is usually the underlying mechanism of an MI.<ref name=HLB2013MI /> MIs are less commonly caused by ]s, which may be due to ], significant emotional stress (often known as ] or ''broken heart syndrome'') and extreme cold, among others.<ref>{{cite web|title=What Causes a Heart Attack?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/causes|website=www.nhlbi.nih.gov|access-date=24 February 2015|date=December 17, 2013|url-status=live|archive-url=https://web.archive.org/web/20150218075735/http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/causes|archive-date=18 February 2015}}</ref><ref>{{cite journal | vauthors = Devlin RJ, Henry JA | title = Clinical review: Major consequences of illicit drug consumption | journal = Critical Care | volume = 12 | issue = 1 | pages = 202 | date = 2008 | pmid = 18279535 | pmc = 2374627 | doi = 10.1186/cc6166 | doi-access = free }}</ref> Many tests are helpful with diagnosis, including ]s (ECGs), blood tests and ].<ref name=HLB2013D>{{cite web|title=How Is a Heart Attack Diagnosed?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/diagnosis|website=www.nhlbi.nih.gov|access-date=24 February 2015|date=December 17, 2013|url-status=live|archive-url= https://web.archive.org/web/20150224044949/http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/diagnosis |archive-date=24 February 2015 }}</ref> An ECG, which is a recording of the heart's electrical activity, may confirm an '''ST elevation MI''' (]), if ] is present.<ref name=Europe2012 /><ref>{{cite web|title=Electrocardiogram | work = NHLBI, NIH |url= https://www.nhlbi.nih.gov/health/health-topics/topics/ekg |access-date=10 April 2017|date=9 December 2016|url-status=live |archive-url= https://web.archive.org/web/20170411140634/https://www.nhlbi.nih.gov/health/health-topics/topics/ekg |archive-date=11 April 2017}}</ref> Commonly used blood tests include ] and less often ].<ref name=HLB2013D />


<!-- Management -->
Immediate treatment for suspected acute myocardial infarction includes ], ], and sublingual ] (colloquially referred to as ] and abbreviated as NTG or GTN). ] is also often given, classically ].<ref>{{cite journal |author=Erhardt L, Herlitz J, Bossaert L, ''et al'' |title=Task force on the management of chest pain |journal=Eur. Heart J. |volume=23 |issue=15 |pages=1153–76 |year=2002 |pmid=12206127 |doi=10.1053/euhj.2002.3194| url=http://eurheartj.oxfordjournals.org/cgi/reprint/23/15/1153|format=PDF}}</ref>
Treatment of an MI is time-critical.<ref name=Davidsons2010>{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine |date=2010 |publisher=Churchill Livingstone/Elsevier |location=Edinburgh |isbn=978-0-7020-3085-7 |edition=21st |pages=588–599}}</ref> ] is an appropriate immediate treatment for a suspected MI.<ref name=Oc2010 /> ] or ]s may be used to help with chest pain; however, they do not improve overall outcomes.<ref name=Europe2012 /><ref name=Oc2010 /> ] is recommended in those with ] or shortness of breath.<ref name=Oc2010>{{cite journal | vauthors = O'Connor RE, Brady W, Brooks SC, Diercks D, Egan J, Ghaemmaghami C, Menon V, O'Neil BJ, Travers AH, Yannopoulos D | display-authors = 6 | title = Part 10: acute coronary syndromes: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 122 | issue = 18 Suppl 3 | pages = S787–817 | date = November 2010 | pmid = 20956226 | doi = 10.1161/CIRCULATIONAHA.110.971028 | doi-access = free }}</ref> In a STEMI, treatments attempt to restore blood flow to the heart and include ] (PCI), where the arteries are pushed open and may be ]ed, or ], where the blockage is removed using medications.<ref name=Europe2012 /> People who have a '''non-ST elevation myocardial infarction''' (]) are often managed with the blood thinner ], with the additional use of PCI in those at high risk.<ref name=Oc2010 /> In people with blockages of multiple coronary arteries and diabetes, ] (CABG) may be recommended rather than ].<ref name=Hamm2011>{{cite journal | vauthors = Hamm CW, Bassand JP, Agewall S, Bax J, Boersma E, Bueno H, Caso P, Dudek D, Gielen S, Huber K, Ohman M, Petrie MC, Sonntag F, Uva MS, Storey RF, Wijns W, Zahger D | display-authors = 6 | title = ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: The Task Force for the management of acute coronary syndromes (ACS) in patients presenting without persistent ST-segment elevation of the European Society of Cardiology (ESC) | journal = European Heart Journal | volume = 32 | issue = 23 | pages = 2999–3054 | date = December 2011 | pmid = 21873419 | doi = 10.1093/eurheartj/ehr236 | doi-access = free }}</ref> After an MI, lifestyle modifications, along with long-term treatment with aspirin, ] and ]s, are typically recommended.<ref name=Europe2012 />


<!-- Epidemiology and culture-->
The patient will receive a number of diagnostic tests, such as an ] (ECG, EKG), a chest ] and ]s to detect elevations in ] (blood tests to detect heart muscle damage). The most often used markers are the ]-MB (CK-MB) fraction and the ] I (TnI) or ] T (TnT) levels. On the basis of the ECG, a distinction is made between '''ST elevation MI''' (STEMI) or '''non-ST elevation MI''' (NSTEMI). Most cases of STEMI are treated with ] or if possible with ] (PCI, angioplasty and stent insertion), provided the hospital has facilities for ]. NSTEMI is managed with medication, although PCI is often performed during hospital admission. In patients who have multiple blockages and who are relatively stable, or in a few extraordinary emergency cases, ] of the blocked coronary artery is an option.
Worldwide, about 15.9 million myocardial infarctions occurred in 2015.<ref name=GBD2015Pre>{{cite journal | vauthors = Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, etal | collaboration = GBD 2015 Disease Injury Incidence Prevalence Collaborators | title = Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1545–1602 | date = October 2016 | pmid = 27733282 | pmc = 5055577 | doi = 10.1016/S0140-6736(16)31678-6 }}</ref> More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI.<ref name=Lancet08>{{cite journal | vauthors = White HD, Chew DP | title = Acute myocardial infarction | journal = Lancet | volume = 372 | issue = 9638 | pages = 570–84 | date = August 2008 | pmid = 18707987 | pmc = 1931354 | doi = 10.1016/S0140-6736(08)61237-4 }}</ref> STEMIs occur about twice as often in men as women.<ref name=AHA2013>{{cite journal | vauthors = O'Gara PT, Kushner FG, Ascheim DD, Casey DE, Chung MK, de Lemos JA, Ettinger SM, Fang JC, Fesmire FM, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX, Anderson JL, Jacobs AK, Halperin JL, Albert NM, Brindis RG, Creager MA, DeMets D, Guyton RA, Hochman JS, Kovacs RJ, Kushner FG, Ohman EM, Stevenson WG, Yancy CW | display-authors = 6 | title = 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines | journal = Circulation | volume = 127 | issue = 4 | pages = e362–425 | date = January 2013 | pmid = 23247304 | doi = 10.1161/CIR.0b013e3182742cf6 | doi-access = free }}</ref> About one million people have an MI each year in the United States.<ref name=HLB2013MI /> In the developed world, the risk of death in those who have had a STEMI is about 10%.<ref name=Europe2012>{{cite journal | vauthors = Steg PG, James SK, Atar D, Badano LP, Blömstrom-Lundqvist C, Borger MA, Di Mario C, Dickstein K, Ducrocq G, Fernandez-Aviles F, Gershlick AH, Giannuzzi P, Halvorsen S, Huber K, Juni P, Kastrati A, Knuuti J, Lenzen MJ, Mahaffey KW, Valgimigli M, van 't Hof A, Widimsky P, Zahger D | display-authors = 6 | title = ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation | journal = European Heart Journal | volume = 33 | issue = 20 | pages = 2569–619 | date = October 2012 | pmid = 22922416 | doi = 10.1093/eurheartj/ehs215 | doi-access = free }}</ref> Rates of MI for a given age have decreased globally between 1990 and 2010.<ref>{{cite journal | vauthors = Moran AE, Forouzanfar MH, Roth GA, Mensah GA, Ezzati M, Flaxman A, Murray CJ, Naghavi M | display-authors = 6 | title = The global burden of ischemic heart disease in 1990 and 2010: the Global Burden of Disease 2010 study | journal = Circulation | volume = 129 | issue = 14 | pages = 1493–501 | date = April 2014 | pmid = 24573351 | pmc = 4181601 | doi = 10.1161/circulationaha.113.004046 }}</ref> In 2011, an MI was one of the top five most expensive conditions during inpatient hospitalizations in the US, with a cost of about $11.5 billion for 612,000 hospital stays.<ref>{{cite web| vauthors = Torio C |title=National Inpatient Hospital Costs: The Most Expensive Conditions by Payer, 2011|url=http://hcup-us.ahrq.gov/reports/statbriefs/sb160.jsp|website=HCUP|access-date=1 May 2017|date=August 2013|url-status=live|archive-url=https://web.archive.org/web/20170314171958/https://www.hcup-us.ahrq.gov/reports/statbriefs/sb160.jsp|archive-date=14 March 2017}}</ref>
{{TOC limit}}


== Terminology ==
The phrase "heart attack" is sometimes used incorrectly to describe ], which may or may not be the result of acute myocardial infarction. A heart attack is different from, but can be the cause of ], which is the stopping of the heartbeat, and ], an abnormal heartbeat. It is also distinct from ], in which the pumping action of the heart is impaired; severe myocardial infarction may lead to heart failure, but not necessarily.
{{Main|Acute coronary syndrome}}
Myocardial infarction (MI) refers to tissue death (]) of the heart muscle (]) caused by ], the lack of oxygen delivery to myocardial tissue. It is a type of ], which describes a sudden or short-term change in symptoms related to blood flow to the heart.{{sfnm|1a1=Morrow|1a2=Braunwald|1y=2016|1pp=1-3|2a1=Dwight|2y=2016|2p=41}} Unlike the other type of acute coronary syndrome, ], a myocardial ] occurs when there is ], which can be estimated by measuring by a ] for ] (the cardiac protein ]).{{sfn|Morrow|Braunwald|2016|pp=1-3}} When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ].<ref name=THIRDDEF />


The phrase "heart attack" is often used non-specifically to refer to myocardial infarction. An MI is different from—but can cause—], where the heart is not contracting at all or so poorly that all vital organs cease to function, thus leading to death.{{sfn|Blumenthal|Margolis|2007|pp=4-5}} It is also distinct from ], in which the pumping action of the heart is impaired. However, an MI may lead to heart failure.{{sfn|Morrow|Bohula|2016|p=295}}
==Epidemiology==
Myocardial infarction is a common presentation of ]. The WHO estimated that in 2002, 12.6 percent of deaths worldwide were from ischemic heart disease.<ref name=WHO-2002/> Ischemic heart disease is the leading cause of death in developed countries, but third to ] and ]s in developing countries.<ref name="UCatlas">{{cite web | title=Cause of Death - UC Atlas of Global Inequality | publisher=Center for Global, International and Regional Studies (CGIRS) at the University of California Santa Cruz | url=http://ucatlas.ucsc.edu/cause.php | dateformat=mdy | accessdate=December 7 2006}}</ref>


== Signs and symptoms ==
In the ], ] are the ], causing a higher ] than ] (] ]).<ref name="causesofdeath">{{cite web | title=Deaths and percentage of total death for the 10 leading causes of death: United States, 2002-2003 | publisher=National Center of Health Statistics | format=] | url=http://www.cdc.gov/nchs/data/hestat/leadingdeaths03_tables.pdf | dateformat=mdy | accessdate=April 17 2007}}</ref> ] is responsible for 1 in 5 deaths in the U.S.. Some 7,200,000 men and 6,000,000 women are living with some form of coronary heart disease. 1,200,000 people suffer a (new or recurrent) coronary attack every year, and about 40% of them die as a result of the attack.<ref name="AHAstats">{{cite web | title=Heart Attack and Angina Statistics | publisher=] | date=2003 | url=http://www.americanheart.org/presenter.jhtml?identifier=4591 | dateformat=mdy | accessdate=December 7 2006}}</ref> This means that roughly every 65 seconds, an American dies of a coronary event.
{{multiple image
| direction = vertical
| width = 250
| image1 = Acute myocardial infarction pain svg hariadhi.svg
| alt1 = View of the chest with common areas of MI coloured
| image2 = Acute_myocardial_infarction_pain_back_svg_hariadhi.svg
| alt2 = View of the back with common areas of MI coloured
| caption2 = Areas where pain is experienced in myocardial infarction, showing common (dark red) and less common (light red) areas on the chest (top) and back (bottom).
}}


Chest pain that may or may not radiate to other parts of the body is the most typical and significant symptom of myocardial infarction. It might be accompanied by other symptoms such as sweating.{{sfn|Morrow|2016|pp=59-61}}
In ], cardiovascular disease (CVD) is the leading cause of death.<ref name="mukhPred">{{cite journal | author=Mukherjee AK. | title=Prediction of coronary heart disease using risk factor categories | journal= J Indian Med Assoc | year=1995 | pmid=8713248}}</ref> The deaths due to CVD in India were 32% of all deaths in 2007 and are expected to rise from 1.17 million in 1990 and 1.59 million in 2000 to 2.03 million in 2010.<ref name="ghafBurd">{{cite journal | author=Ghaffar A, Reddy KS and Singhi M | title=Burden of non-communicable diseases in South Asia | journal= BMJ | year=2004 | volume=328 | pages=807–810 | format=] | url=http://www.bmj.com/cgi/reprint/328/7443/807.pdf | doi=10.1136/bmj.328.7443.807 | pmid=15070638}}</ref> Although a relatively new epidemic in India, it has quickly become a major health issue with deaths due to CVD expected to double during 1985-2015.<ref name="rastPhys">{{cite journal | author=Rastogi T, Vaz M, Spiegelman D, Reddy KS, Bharathi AV, Stampfer MJ, Willett WC and Ascherio1 A | title=Physical activity and risk of coronary heart disease in India | journal=Int. J. Epidemiol | year=2004 | volume=33 | pages=1–9 | format=] | url=http://ije.oxfordjournals.org/cgi/reprint/33/4/759.pdf | doi = 10.1093/ije/dyh042 | pmid=15044412}}</ref><ref name="GuptEsca">{{cite journal | author=Gupta R. | title=Escalating Coronary Heart Disease and Risk Factors in South Asians | journal=Indian Heart Journal | year=2007 | pages=214–17 | format=] | url=http://indianheartjournal.com/editorial007.pdf}}</ref> Mortality estimates due to CVD vary widely by state, ranging from 10% in Meghalaya to 49% in Punjab (percentage of all deaths). Punjab (49%), Goa (42%), Tamil Nadu (36%) and Andhra Pradesh (31%) have the highest CVD related mortality estimates.<ref name="guptCorr">{{cite journal | author=Gupta R, Misra A, Pais P, Rastogi P and Gupta VP. | title=Correlation of regional cardiovascular disease mortality in India with lifestyle and nutritional factors | journal=International Journal of Cardiology | year=2006 | volume=108 | issue=3 | pages=291–300 | format=] | url=http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6T16-4GFV5CY-4-3&_cdi=4882&_user=209690&_orig=search&_coverDate=04%2F14%2F2006&_sk=998919996&view=c&wchp=dGLzVlz-zSkzV&md5=050edf99a813f475b985c8d590c86228&ie=/sdarticle.pdf | doi = 10.1016/j.ijcard.2005.05.044}}</ref> State-wise differences are correlated with prevalence of specific dietary risk factors in the states. Moderate physical exercise is associated with reduced incidence of CVD in India (those who exercise have less than half the risk of those who don't).<ref name="rastPhys">{{cite journal | author=Rastogi T, Vaz M, Spiegelman D, Reddy KS, Bharathi AV, Stampfer MJ, Willett WC and Ascherio1 A | title=Physical activity and risk of coronary heart disease in India | journal=Int. J. Epidemiol | year=2004 | volume=33 | pages=1–9 | format=] | url=http://ije.oxfordjournals.org/cgi/reprint/33/4/759.pdf | doi = 10.1093/ije/dyh042 | pmid=15044412}}</ref> CVD also affects Indians at a younger age (in their 30s and 40s) than is typical in other countries.


===Risk factors=== === Pain ===
] is one of the most common symptoms of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper ].<ref name=Harrisons2015>{{Cite book|title=Harrison's principles of internal medicine | vauthors = Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J |publisher=McGraw Hill Education|year=2015|isbn=978-0-07-180215-4|pages=1593–1610|oclc=923181481}}</ref>{{sfn|Morrow|2016|pp=59-60}} The pain most suggestive of an acute MI, with the highest ], is pain radiating to the right arm and shoulder.<ref name=Harrisons2015B>{{Cite book|title=Harrison's Principles of Internal Medicine | vauthors = Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J |publisher=McGraw Hill Education|year=2015|isbn=978-0-07-180215-4|pages=98–99|oclc=923181481}}</ref>{{sfn|Morrow|2016|pp=59-60}} Similarly, chest pain similar to a previous heart attack is also suggestive.<ref name="Gupta2016">{{cite journal | vauthors = Gupta R, Munoz R | title = Evaluation and Management of Chest Pain in the Elderly | journal = Emergency Medicine Clinics of North America | volume = 34 | issue = 3 | pages = 523–42 | date = August 2016 | pmid = 27475013 | doi = 10.1016/j.emc.2016.04.006 }}</ref> The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes.<ref name="THIRDDEF">{{cite journal | vauthors = Thygesen K, Alpert JS, Jaffe AS, Simoons ML, Chaitman BR, White HD, Katus HA, Lindahl B, Morrow DA, Clemmensen PM, Johanson P, Hod H, Underwood R, Bax JJ, Bonow RO, Pinto F, Gibbons RJ, Fox KA, Atar D, Newby LK, Galvani M, Hamm CW, Uretsky BF, Steg PG, Wijns W, Bassand JP, Menasché P, Ravkilde J, Ohman EM, Antman EM, Wallentin LC, Armstrong PW, Simoons ML, Januzzi JL, Nieminen MS, Gheorghiade M, Filippatos G, Luepker RV, Fortmann SP, Rosamond WD, Levy D, Wood D, Smith SC, Hu D, Lopez-Sendon JL, Robertson RM, Weaver D, Tendera M, Bove AA, Parkhomenko AN, Vasilieva EJ, Mendis S | display-authors = 6 | title = Third universal definition of myocardial infarction | journal = Circulation | volume = 126 | issue = 16 | pages = 2020–35 | date = October 2012 | pmid = 22923432 | doi = 10.1161/CIR.0b013e31826e1058 | doi-access = free }}</ref> It might be described as pressure, tightness, knifelike, tearing, burning sensation (all these are also manifested during other diseases). It could be felt as an unexplained anxiety, and pain might be absent altogether.{{sfn|Morrow|2016|pp=59-60}} ], in which a person localizes the chest pain by clenching one or both fists over their ], has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor ].<ref name="pmid17208083">{{cite journal | vauthors = Marcus GM, Cohen J, Varosy PD, Vessey J, Rose E, Massie BM, Chatterjee K, Waters D | display-authors = 6 | title = The utility of gestures in patients with chest discomfort | journal = The American Journal of Medicine | volume = 120 | issue = 1 | pages = 83–9 | date = January 2007 | pmid = 17208083 | doi = 10.1016/j.amjmed.2006.05.045 }}</ref>
Risk factors for ] are generally risk factors for myocardial infarction:
*]
*] sex<ref name="Framingham1998">{{cite journal | author=Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. | title=Prediction of coronary heart disease using risk factor categories | journal=Circulation | year=1998 | volume=97 | issue=18 | pages=1837–47 | format=] | url=http://circ.ahajournals.org/cgi/reprint/97/18/1837.pdf | pmid=9603539}}</ref>
*]
*] (more accurately ], especially high ] and low ])
*] (high ], a toxic blood ] that is elevated when intakes of ] B2, B6, B12 and ] are insufficient)
*] (with or without ])
*]
*]<ref name="Yusuf-2005">{{cite journal | author=Yusuf S, Hawken S, Ounpuu S, Bautista L, Franzosi MG, Commerford P, Lang CC, Rumboldt Z, Onen CL, Lisheng L, Tanomsup S, Wangai P Jr, Razak F, Sharma AM, Anand SS; INTERHEART Study Investigators. | title=Obesity and the risk of myocardial infarction in 27,000 participants from 52 countries: a case-control study | journal=Lancet | year=2005 | volume=366 | issue=9497 | pages=1640–9 | pmid=16271645 | doi = 10.1016/S0140-6736(05)67663-5}}</ref> (defined by a ] of more than 30 kg/m², or alternatively by waist circumference or ]).
*] Occupations with high stress index are known to have susceptibility for ].


Typically, chest pain because of ischemia, be it unstable angina or myocardial infarction, lessens with the use of ], but nitroglycerin may also relieve chest pain arising from non-cardiac causes.{{sfnm|1a1=Allison|1a2=Murphy|1y=2012|1p=197|2a1=Morrow|2y=2016|2p=60}}
Many of these risk factors are modifiable, so many heart attacks can be prevented by maintaining a healthier lifestyle. Physical activity, for example, is associated with a lower risk profile.<ref name="Jensen-1991">{{cite journal | author=Jensen G, Nyboe J, Appleyard M, Schnohr P. | title=Risk factors for acute myocardial infarction in Copenhagen, II: Smoking, alcohol intake, physical activity, obesity, oral contraception, diabetes, lipids, and blood pressure | journal=Eur Heart J | year=1991 | volume=12 | issue=3 | pages=298–308 | pmid=2040311}}</ref> Non-modifiable risk factors include age, sex, and family history of an early heart attack (before the age of 60), which is thought of as reflecting a ].<ref name="Framingham1998"/>


=== Other ===
] factors such as a shorter ] and lower ] (particularly in women), and unmarried cohabitation may also contribute to the risk of MI.<ref name="Nyboe-1989">{{cite journal | author=Nyboe J, Jensen G, Appleyard M, Schnohr P. | title=Risk factors for acute myocardial infarction in Copenhagen. I: Hereditary, educational and socioeconomic factors. Copenhagen City Heart Study | journal=Eur Heart J | year=1989 | volume=10 | issue=10 | pages=910–6 | pmid=2598948}}</ref> To understand epidemiological study results, it's important to note that many factors associated with MI mediate their risk via other factors. For example, the effect of education is partially based on its effect on income and ].<ref name="Nyboe-1989"/>
Chest pain may be accompanied by ], nausea or vomiting, and ],<ref name=THIRDDEF /><ref name=Harrisons2015B /> and these symptoms may also occur without any pain at all.<ref name=Harrisons2015 /> Dizziness or lightheadedness is common and occurs due to reduction in oxygen and blood to the brain. In females, the most common symptoms of myocardial infarction include shortness of breath, weakness, and ].<ref name="ACSwomen">{{cite journal | vauthors = Canto JG, Goldberg RJ, Hand MM, Bonow RO, Sopko G, Pepine CJ, Long T | title = Symptom presentation of females with acute coronary syndromes: myth vs reality | journal = Archives of Internal Medicine | volume = 167 | issue = 22 | pages = 2405–2413 | date = December 2007 | pmid = 18071161 | doi = 10.1001/archinte.167.22.2405 }}</ref> Females are more likely to have unusual or unexplained tiredness and nausea or vomiting as symptoms.<ref>{{cite web |title=Heart Attack Symptoms, Risk, and Recovery |url=https://www.cdc.gov/heartdisease/heart_attack.htm |website=CDC.gov |publisher=U.S. Department of Health & Human Services |access-date=July 20, 2021}}</ref> Females having heart attacks are more likely to have palpitations, back pain, labored breath, vomiting, and left arm pain than males, although the studies showing these differences had high variability.<ref>{{cite journal | vauthors = Coventry LL, Finn J, Bremner AP | title = Sex differences in symptom presentation in acute myocardial infarction: a systematic review and meta-analysis | journal = Heart & Lung | volume = 40 | issue = 6 | pages = 477–491 | date = November–December 2011 | pmid = 22000678 | doi = 10.1016/j.hrtlng.2011.05.001 }}</ref> Females are less likely to report chest pain during a heart attack and more likely to report nausea, jaw pain, neck pain, cough, and fatigue, although these findings are inconsistent across studies.<ref>{{cite journal | vauthors = Chen W, Woods SL, Puntillo KA | title = Sex differences in symptoms associated with acute myocardial infarction: a review of the research | journal = Heart & Lung | volume = 34 | issue = 4 | pages = 240–247 | date = July–August 2005 | pmid = 16027643 | doi = 10.1016/j.hrtlng.2004.12.004 }}</ref> Females with heart attacks also had more indigestion, ], ], and loss of consciousness.<ref>{{cite journal | vauthors = DeVon HA, Zerwic JJ | title = Symptoms of acute coronary syndromes: are there gender differences? A review of the literature | journal = Heart & Lung | volume = 31 | issue = 4 | pages = 235–245 | date = July–August 2002 | pmid = 12122387 | doi = 10.1067/mhl.2002.126105 }}</ref> ] is a common, and sometimes the only symptom, occurring when damage to the heart limits the ] of the ], with breathlessness arising either from ] or ].<ref name=Harrisons2015 /><ref>{{cite web| vauthors = Ashton R, Raman D | title = Dyspnea |url= http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/pulmonary/dyspnea/ |website=www.clevelandclinicmeded.com|publisher=Cleveland Clinic |access-date=24 May 2017 |url-status=live |archive-url=https://web.archive.org/web/20170711084207/http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/pulmonary/dyspnea/|archive-date=11 July 2017}}</ref>


Other less common symptoms include weakness, ], ]s, and abnormalities in ] or ].<ref name=Davidsons2010 /> These symptoms are likely induced by a massive surge of ] from the ], which occurs in response to pain and, where present, low ].<ref>{{cite book| vauthors = Lilly LS |title=Pathophysiology of Heart Disease: A Collaborative Project of Medical Students and Faculty|date=2012|publisher=Lippincott Williams & Wilkins |isbn=978-1-4698-1668-5 |page=172 |url= https://books.google.com/books?id=0lxSGJYeXikC&pg=PA172 |url-status=live |archive-url= https://web.archive.org/web/20170728135942/https://books.google.com.au/books?id=0lxSGJYeXikC&pg=PA172&lpg=PA172 |archive-date=2017-07-28 }}</ref> ] can occur in myocardial infarctions due to inadequate blood flow to the ] and ], and ], frequently due to the development of ].<ref name='ESC STEMI'>{{cite journal | vauthors = Van de Werf F, Bax J, Betriu A, Blomstrom-Lundqvist C, Crea F, Falk V, Filippatos G, Fox K, Huber K, Kastrati A, Rosengren A, Steg PG, Tubaro M, Verheugt F, Weidinger F, Weis M | display-authors = 6 | title = Management of acute myocardial infarction in patients presenting with persistent ST-segment elevation: the Task Force on the Management of ST-Segment Elevation Acute Myocardial Infarction of the European Society of Cardiology | journal = European Heart Journal | volume = 29 | issue = 23 | pages = 2909–2945 | date = December 2008 | pmid = 19004841 | doi = 10.1093/eurheartj/ehn416 | doi-access = free }}</ref> When the brain was without oxygen for too long due to a myocardial infarction, ] and ] can occur. Cardiac arrest, and atypical symptoms such as ], occur more frequently in females, the elderly, those with diabetes, in people who have just had surgery, and in critically ill patients.<ref name=THIRDDEF />
Women who use ]s have a modestly increased risk of myocardial infarction, especially in the presence of other risk factors, such as smoking.<ref name="Khader-2003">{{cite journal | author=Khader YS, Rice J, John L, Abueita O. | title=Oral contraceptives use and the risk of myocardial infarction: a meta-analysis | journal=Contraception | year=2003 | volume=68 | issue=1 | pages=11–7 | pmid=12878281 | doi = 10.1016/S0010-7824(03)00073-8}}</ref>


=== Absence ===
Inflammation is known to be an important step in the process of ] formation.<ref name="Wilson-2006">{{cite journal | author=Wilson AM, Ryan MC, Boyle AJ. | title=The novel role of C-reactive protein in cardiovascular disease: risk marker or pathogen | journal=Int J Cardiol | year=2006 | volume=106 | issue=3 | pages=291–7 | pmid=16337036 | doi = 10.1016/j.ijcard.2005.01.068}}</ref> ] (CRP) is a sensitive but non-specific ] for ]. Elevated CRP blood levels, especially measured with high sensitivity assays, can predict the risk of MI, as well as ] and development of diabetes.<ref name="Wilson-2006"/> Moreover, some drugs for MI might also reduce CRP levels.<ref name="Wilson-2006"/> The use of high sensitivity CRP assays as a means of ] the general population is advised against, but it may be used optionally at the physician's discretion, in patients who already present with other risk factors or known ].<ref name="Pearson-2003">{{cite journal | author=Pearson TA, Mensah GA, Alexander RW, Anderson JL, Cannon RO 3rd, Criqui M, Fadl YY, Fortmann SP, Hong Y, Myers GL, Rifai N, Smith SC Jr, Taubert K, Tracy RP, Vinicor F; Centers for Disease Control and Prevention; American Heart Association. | title=Markers of inflammation and cardiovascular disease: application to clinical and public health practice: A statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association | journal=Circulation | year=2003 | volume=107 | issue=3 | pages=499–511 | format=] | url=http://circ.ahajournals.org/cgi/reprint/107/3/499.pdf | pmid=12551878 | doi = 10.1161/01.CIR.0000052939.59093.45}}</ref> Whether CRP plays a direct role in atherosclerosis remains uncertain.<ref name="Wilson-2006"/>
<!--Silent-->
"Silent" myocardial infarctions can happen without any symptoms at all.<ref name = Val2011 /> These cases can be discovered later on ], using blood enzyme tests, or at ] after a person has died. Such silent myocardial infarctions represent between 22 and 64% of all infarctions,<ref name = Val2011 /> and are more common in the ],<ref name = Val2011 /> in those with ]<ref name=Davidsons2010 /> and after ]. In people with diabetes, differences in ], ], and ] factors have been cited as possible explanations for the lack of symptoms.<ref name="Diabetologica2004-David">{{cite journal | vauthors = Davis TM, Fortun P, Mulder J, Davis WA, Bruce DG | title = Silent myocardial infarction and its prognosis in a community-based cohort of Type 2 diabetic patients: the Fremantle Diabetes Study | journal = Diabetologia | volume = 47 | issue = 3 | pages = 395–399 | date = March 2004 | pmid = 14963648 | doi = 10.1007/s00125-004-1344-4 | s2cid = 12567614 }}</ref> In heart transplantation, the ] heart is not fully innervated by the nervous system of the recipient.<ref name=rubin>{{cite book | vauthors = Rubin E, Gorstein F, Rubin R, Schwarting R, Strayer D | title = Rubin's Pathology&nbsp;— Clinicopathological Foundations of Medicine | publisher = Lippincott Williams & Wilkins | year = 2001 | location = Maryland | page = 549 | isbn = 978-0-7817-4733-2 }}</ref>


== Risk factors ==
Inflammation in ] disease may be linked coronary heart disease, and since ] is very common, this could have great consequences for ].<ref name="Janket-2003">{{cite journal | author=Janket SJ, Baird AE, Chuang SK, Jones JA. | title=Meta-analysis of periodontal disease and risk of coronary heart disease and stroke | journal=Oral Surg Oral Med Oral Pathol Oral Radiol Endod. | year=2003 | volume=95 | issue=5 | pages=559–69 | pmid=12738947 | doi=10.1038/sj.ebd.6400272}}</ref> ] studies measuring ] levels against typical periodontitis-causing ] found that such antibodies were more present in subjects with coronary heart disease.<ref name="Pihlstrom-2005">{{cite journal | author=Pihlstrom BL, Michalowicz BS, Johnson NW. | title=Periodontal diseases | journal=Lancet | year=2005 | volume=366 | issue=9499 | pages=1809–20 | pmid=16298220 | doi = 10.1016/S0140-6736(05)67728-8}}</ref> Periodontitis tends to increase blood levels of CRP, ] and ];<ref name="Scannapieco-2003">{{cite journal | author=Scannapieco FA, Bush RB, Paju S. | title=Associations between periodontal disease and risk for atherosclerosis, cardiovascular disease, and stroke. A systematic review | journal=Ann Periodontol | year=2003 | volume=8 | issue=1 | pages=38–53 | pmid=14971247 | doi = 10.1902/annals.2003.8.1.38}}</ref> thus, periodontitis may mediate its effect on MI risk via other risk factors.<ref name="D'Aiuto-2006">{{cite journal | author=D'Aiuto F, Parkar M, Nibali L, Suvan J, Lessem J, Tonetti MS. | title=Periodontal infections cause changes in traditional and novel cardiovascular risk factors: results from a randomized controlled clinical trial | journal=Am Heart J | year=2006 | volume=151 | issue=5 | pages=977–84 | pmid=16644317 | doi=10.1016/j.ahj.2005.06.018}}</ref> ] suggests that periodontal bacteria can promote aggregation of ] and promote the formation of ]s.<ref name="Lourbakos-2001">{{cite journal | author=Lourbakos A, Yuan YP, Jenkins AL, Travis J, Andrade-Gordon P, Santulli R, Potempa J, Pike RN. | title=Activation of protease-activated receptors by gingipains from Porphyromonas gingivalis leads to platelet aggregation: a new trait in microbial pathogenicity | journal=Blood | year=2001 | volume=97 | issue=12 | pages=3790–7 | format=] | url=http://bloodjournal.hematologylibrary.org/cgi/reprint/97/12/3790.pdf | pmid=11389018 | doi = 10.1182/blood.V97.12.3790}}</ref><ref name="Qi-2003">{{cite journal | author=Qi M, Miyakawa H, Kuramitsu HK. | title=Porphyromonas gingivalis induces murine macrophage foam cell formation | journal=Microb Pathog | year=2003 | volume=35 | issue=6 | pages=259–67 | pmid=14580389 | doi = 10.1016/j.micpath.2003.07.002}}</ref> A role for specific periodontal bacteria has been suggested but remains to be established.<ref name="Spahr-2006">{{cite journal | author=Spahr A, Klein E, Khuseyinova N, Boeckh C, Muche R, Kunze M, Rothenbacher D, Pezeshki G, Hoffmeister A, Koenig W. | title=Periodontal infections and coronary heart disease: role of periodontal bacteria and importance of total pathogen burden in the Coronary Event and Periodontal Disease (CORODONT) study | journal=Arch Intern Med | year=2006 | volume=166 | issue=5 | pages=554–9 | pmid=16534043 | doi = 10.1001/archinte.166.5.554}}</ref>
The most prominent risk factors for myocardial infarction are older age, actively ], ], ], and total ] and ] levels.{{sfn|Gaziano|Gaziano|2016|p=11-22}} Many risk factors of myocardial infarction are shared with ], the primary cause of myocardial infarction,<ref name=Davidsons2010 /> with other risk factors including male sex, low levels of physical activity, a past ], ], and ].<ref name=Davidsons2010 /> Risk factors for myocardial disease are often included in risk factor stratification scores, such as the ].<ref name=AHA2013 /> At any given age, men are more at risk than women for the development of cardiovascular disease.<ref name="EUROPEAN2012">{{cite journal | vauthors = Perk J, De Backer G, Gohlke H, Graham I, Reiner Z, Verschuren M, Albus C, Benlian P, Boysen G, Cifkova R, Deaton C, Ebrahim S, Fisher M, Germano G, Hobbs R, Hoes A, Karadeniz S, Mezzani A, Prescott E, Ryden L, Scherer M, Syvänne M, Scholte op Reimer WJ, Vrints C, Wood D, Zamorano JL, Zannad F | display-authors = 6 | title = European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts) | journal = European Heart Journal | volume = 33 | issue = 13 | pages = 1635–701 | date = July 2012 | pmid = 22555213 | doi = 10.1093/eurheartj/ehs092 | doi-access = free }}</ref> ] is a known risk factor, particularly high ], low ], and high ].<ref name="pmid=16697342">{{cite journal | vauthors = Smith SC, Allen J, Blair SN, Bonow RO, Brass LM, Fonarow GC, Grundy SM, Hiratzka L, Jones D, Krumholz HM, Mosca L, Pearson T, Pfeffer MA, Taubert KA | display-authors = 6 | title = AHA/ACC guidelines for secondary prevention for patients with coronary and other atherosclerotic vascular disease: 2006 update endorsed by the National Heart, Lung, and Blood Institute | journal = Journal of the American College of Cardiology | volume = 47 | issue = 10 | pages = 2130–9 | date = May 2006 | pmid = 16697342 | doi = 10.1016/j.jacc.2006.04.026 | doi-access = free }}</ref>


Many risk factors for myocardial infarction are potentially modifiable, with the most important being ] (including ]).<ref name=Davidsons2010 /> Smoking appears to be the cause of about 36% and obesity the cause of 20% of ].<ref name=Kivi2012 /> Lack of physical activity has been linked to 7–12% of cases.<ref name=Kivi2012 /><ref>{{cite journal | vauthors = Lee IM, Shiroma EJ, Lobelo F, Puska P, Blair SN, Katzmarzyk PT | title = Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy | journal = Lancet | volume = 380 | issue = 9838 | pages = 219–29 | date = July 2012 | pmid = 22818936 | pmc = 3645500 | doi = 10.1016/S0140-6736(12)61031-9 }}</ref> Less common causes include stress-related causes such as ], which accounts for about 3% of cases,<ref name=Kivi2012>{{cite journal | vauthors = Kivimäki M, Nyberg ST, Batty GD, Fransson EI, Heikkilä K, Alfredsson L, Bjorner JB, Borritz M, Burr H, Casini A, Clays E, De Bacquer D, Dragano N, Ferrie JE, Geuskens GA, Goldberg M, Hamer M, Hooftman WE, Houtman IL, Joensuu M, Jokela M, Kittel F, Knutsson A, Koskenvuo M, Koskinen A, Kouvonen A, Kumari M, Madsen IE, Marmot MG, Nielsen ML, Nordin M, Oksanen T, Pentti J, Rugulies R, Salo P, Siegrist J, Singh-Manoux A, Suominen SB, Väänänen A, Vahtera J, Virtanen M, Westerholm PJ, Westerlund H, Zins M, Steptoe A, Theorell T | display-authors = 6 | title = Job strain as a risk factor for coronary heart disease: a collaborative meta-analysis of individual participant data | journal = Lancet | volume = 380 | issue = 9852 | pages = 1491–7 | date = October 2012 | pmid = 22981903 | pmc = 3486012 | doi = 10.1016/S0140-6736(12)60994-5 }}</ref> and chronic high stress levels.<ref name="pmid=22473079">{{cite journal | vauthors = Steptoe A, Kivimäki M | title = Stress and cardiovascular disease | journal = Nature Reviews. Cardiology | volume = 9 | issue = 6 | pages = 360–70 | date = April 2012 | pmid = 22473079 | doi = 10.1038/nrcardio.2012.45 | s2cid = 27925226 }}</ref>
], ], a diagonal ] (]<ref name="pmid11108067">{{cite journal |author=Davis TM, Balme M, Jackson D, Stuccio G, Bruce DG |title=The diagonal ear lobe crease (Frank's sign) is not associated with coronary artery disease or retinopathy in type 2 diabetes: the Fremantle Diabetes Study |journal=Aust N Z J Med |volume=30 |issue=5 |pages=573–7 |year=2000 |month=October |pmid=11108067 |doi= |url=}}</ref>) and possibly other ] features have been suggested as independent risk factors for MI.<ref name="Lichstein-1974">{{cite journal | author=Lichstein E, Chadda KD, Naik D, Gupta PK. | title=Diagonal ear-lobe crease: prevalence and implications as a coronary risk factor | journal=N Engl J Med | year=1974 | volume=290 | issue=11 | pages=615–6 | pmid=4812503}}</ref>
Their role remains controversial; a common denominator of these signs and the risk of MI is supposed, possibly genetic. <ref name="Miric-1998">{{cite journal | author=Miric D, Fabijanic D, Giunio L, Eterovic D, Culic V, Bozic I, Hozo I. | title=Dermatological indicators of coronary risk: a case-control study | journal=Int J Cardiol | year=1998 | volume=67 | issue=3 | pages=251–5 | pmid=9894707 | doi=10.1016/S0167-5273(98)00313-1}}</ref>


=== Diet ===
] deposition is another part of atherosclerotic plaque formation. Calcium deposits in the coronary arteries can be detected with ]s. Several studies have shown that coronary calcium can provide predictive information beyond that of classical risk factors.<ref name="JAMAcalc">{{cite journal |author=Greenland P, LaBree L, Azen SP, Doherty TM, Detrano RC |title=Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals |journal=JAMA |volume=291 |issue=2 |pages=210–5 |year=2004 |pmid=14722147 |doi=10.1001/jama.291.2.210 |url=http://jama.ama-assn.org/cgi/pmidlookup?view=long&pmid=14722147}}</ref><ref name="NEJMcalc">{{cite journal |author=Detrano R, Guerci AD, Carr JJ, ''et al'' |title=Coronary calcium as a predictor of coronary events in four racial or ethnic groups |journal=N. Engl. J. Med. |volume=358 |issue=13 |pages=1336–45 |year=2008 |pmid=18367736 |doi=10.1056/NEJMoa072100 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=18367736&promo=ONFLNS19}}</ref><ref name="ACCcalc">{{cite journal |author=Arad Y, Goodman KJ, Roth M, Newstein D, Guerci AD |title=Coronary calcification, coronary disease risk factors, C-reactive protein, and atherosclerotic cardiovascular disease events: the St. Francis Heart Study |journal=J. Am. Coll. Cardiol. |volume=46 |issue=1 |pages=158–65 |year=2005 |pmid=15992651 |doi=10.1016/j.jacc.2005.02.088 |url=http://linkinghub.elsevier.com/retrieve/pii/S0735-1097(05)01031-4}}</ref>
There is varying evidence about the importance of ] in the development of myocardial infarctions. Eating polyunsaturated fat instead of ]s has been shown in studies to be associated with a decreased risk of myocardial infarction,<ref name=":1">{{cite journal | vauthors = Hooper L, Martin N, Jimoh OF, Kirk C, Foster E, Abdelhamid AS | title = Reduction in saturated fat intake for cardiovascular disease | journal = The Cochrane Database of Systematic Reviews | volume = 2020 | pages = CD011737 | date = August 2020 | issue = 8 | pmid = 32827219 | doi = 10.1002/14651858.CD011737.pub3 | pmc = 8092457 }}</ref> while other studies find little evidence that reducing dietary saturated fat or increasing ] intake affects heart attack risk.<ref name=Chow2014>{{cite journal | vauthors = Chowdhury R, Warnakula S, Kunutsor S, Crowe F, Ward HA, Johnson L, Franco OH, Butterworth AS, Forouhi NG, Thompson SG, Khaw KT, Mozaffarian D, Danesh J, Di Angelantonio E | display-authors = 6 | title = Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis | journal = Annals of Internal Medicine | volume = 160 | issue = 6 | pages = 398–406 | date = March 2014 | pmid = 24723079 | doi = 10.7326/M13-1788 }}</ref><ref>{{cite journal | vauthors = de Souza RJ, Mente A, Maroleanu A, Cozma AI, Ha V, Kishibe T, Uleryk E, Budylowski P, Schünemann H, Beyene J, Anand SS | display-authors = 6 | title = Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies | journal = BMJ | volume = 351 | pages = h3978 | date = August 2015 | pmid = 26268692 | pmc = 4532752 | doi = 10.1136/bmj.h3978 }}</ref> Dietary cholesterol does not appear to have a significant effect on blood cholesterol and thus recommendations about its consumption may not be needed.<ref>{{cite web|title=Scientific Report of the 2015 Dietary Guidelines Advisory Committee|url=http://health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf|website=health.gov|page=17|date=Feb 2015|url-status=dead|archive-url=https://web.archive.org/web/20160503071439/http://health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf|archive-date=2016-05-03|access-date=2015-03-05}}</ref> ] do appear to increase risk.<ref name=Chow2014 /> Acute and prolonged intake of high quantities of alcoholic drinks (3–4 or more daily) increases the risk of a heart attack.<ref name=Krenz2012>{{cite journal | vauthors = Krenz M, Korthuis RJ | title = Moderate ethanol ingestion and cardiovascular protection: from epidemiologic associations to cellular mechanisms | journal = Journal of Molecular and Cellular Cardiology | volume = 52 | issue = 1 | pages = 93–104 | date = January 2012 | pmid = 22041278 | pmc = 3246046 | doi = 10.1016/j.yjmcc.2011.10.011 }}</ref>


=== Genetics ===
==Pathophysiology==<!-- This section is linked from ] -->
Family history of ] or MI, particularly if one has a male first-degree relative (father, brother) who had a myocardial infarction before age 55 years, or a female first-degree relative (mother, sister) less than age 65 increases a person's risk of MI.<ref name="EUROPEAN2012" />


] have found 27 genetic variants that are associated with an increased risk of myocardial infarction.<ref name="Genomics of Cardiovascular Disease" /> The strongest association of MI has been found with ] on the short arm ''p'' at ] 21, which contains genes CDKN2A and 2B, although the ] that are implicated are within a non-coding region.<ref name="Genomics of Cardiovascular Disease" /> The majority of these variants are in regions that have not been previously implicated in coronary artery disease. The following genes have an association with MI: ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ], ].<ref name="Genomics of Cardiovascular Disease">{{cite journal | vauthors = O'Donnell CJ, Nabel EG | title = Genomics of cardiovascular disease | journal = The New England Journal of Medicine | volume = 365 | issue = 22 | pages = 2098–109 | date = December 2011 | pmid = 22129254 | doi = 10.1056/NEJMra1105239 | doi-access =free }}</ref>
] ] slowly builds up in the inner lining of a ] and then suddenly ruptures, totally occluding the artery and preventing blood flow downstream.]]


=== Other ===
{{main|Acute coronary syndrome}}
{{See also|Overwork|Karoshi|996 working hour system}}
The risk of having a myocardial infarction increases with older age, low physical activity, and low ].<ref name="EUROPEAN2012" /> Heart attacks appear to occur more commonly in the morning hours, especially between 6AM and noon.<ref name="Culic2007">{{cite journal | vauthors = Culić V | title = Acute risk factors for myocardial infarction | journal = International Journal of Cardiology | volume = 117 | issue = 2 | pages = 260–9 | date = April 2007 | pmid = 16860887 | doi = 10.1016/j.ijcard.2006.05.011 }}</ref> Evidence suggests that heart attacks are at least three times more likely to occur in the morning than in the late evening.<ref name="Shaw2009">{{cite journal | vauthors = Shaw E, Tofler GH | title = Circadian rhythm and cardiovascular disease | journal = Current Atherosclerosis Reports | volume = 11 | issue = 4 | pages = 289–95 | date = July 2009 | pmid = 19500492 | doi = 10.1007/s11883-009-0044-4 | s2cid = 43626425 }}</ref> ] is also associated with a higher risk of MI.<ref name=Vyas2012>{{cite journal | vauthors = Vyas MV, Garg AX, Iansavichus AV, Costella J, Donner A, Laugsand LE, Janszky I, Mrkobrada M, Parraga G, Hackam DG | display-authors = 6 | title = Shift work and vascular events: systematic review and meta-analysis | journal = BMJ | volume = 345 | pages = e4800 | date = July 2012 | pmid = 22835925 | pmc = 3406223 | doi = 10.1136/bmj.e4800 }}</ref> One analysis has found an increase in heart attacks immediately following the start of ].<ref>{{cite journal | vauthors = Janszky I, Ljung R | title = Shifts to and from daylight saving time and incidence of myocardial infarction | journal = The New England Journal of Medicine | volume = 359 | issue = 18 | pages = 1966–8 | date = October 2008 | pmid = 18971502 | doi = 10.1056/NEJMc0807104 | s2cid = 205040478 | doi-access = free }}</ref>


Women who use ]s have a modestly increased risk of myocardial infarction, especially in the presence of other risk factors.<ref>{{cite journal | vauthors = Roach RE, Helmerhorst FM, Lijfering WM, Stijnen T, Algra A, Dekkers OM | title = Combined oral contraceptives: the risk of myocardial infarction and ischemic stroke | journal = The Cochrane Database of Systematic Reviews | issue = 8 | pages = CD011054 | date = August 2015 | volume = 2015 | pmid = 26310586 | pmc = 6494192 | doi = 10.1002/14651858.CD011054.pub2 | hdl = 1874/340787 }}</ref> The use of ] (NSAIDs), even for as short as a week, increases risk.<ref>{{cite journal | vauthors = Bally M, Dendukuri N, Rich B, Nadeau L, Helin-Salmivaara A, Garbe E, Brophy JM | title = Risk of acute myocardial infarction with NSAIDs in real world use: bayesian meta-analysis of individual patient data | journal = BMJ | volume = 357 | pages = j1909 | date = May 2017 | pmid = 28487435 | pmc = 5423546 | doi = 10.1136/bmj.j1909 }}</ref>
Acute myocardial infarction refers to two subtypes of ], namely '''non-ST-elevated myocardial infarction''' and '''ST-elevated myocardial infarction''', which are most frequently (but not always) a manifestation of ]. The most common triggering event is the disruption of an ] ] in an epicardial coronary artery, which leads to a clotting cascade, sometimes resulting in total occlusion of the artery. Atherosclerosis is the gradual buildup of ] and fibrous tissue in plaques in the wall of ] (in this case, the ]), typically over decades. Blood stream column irregularities visible on angiography reflect artery ] narrowing as a result of decades of advancing atherosclerosis. Plaques can become unstable, rupture, and additionally promote a ] (blood clot) that occludes the artery; this can occur in minutes. When a severe enough plaque rupture occurs in the coronary vasculature, it leads to myocardial infarction (necrosis of downstream myocardium).


] in women under the age of 40 is an identified risk factor.<ref>{{cite journal | vauthors = Mu F, Rich-Edwards J, Rimm EB, Spiegelman D, Missmer SA | title = Endometriosis and Risk of Coronary Heart Disease | journal = Circulation: Cardiovascular Quality and Outcomes | volume = 9 | issue = 3 | pages = 257–64 | date = May 2016 | pmid = 27025928 | pmc = 4940126 | doi = 10.1161/CIRCOUTCOMES.115.002224 }}</ref>
If impaired blood flow to the heart lasts long enough, it triggers a process called the ]; the heart cells die (chiefly through ]) and do not grow back. A ] ] forms in its place. Recent studies indicate that another form of cell death called ] also plays a role in the process of tissue damage subsequent to myocardial infarction.<ref name="Krijnen-2002">{{cite journal | author=Krijnen PA, Nijmeijer R, Meijer CJ, Visser CA, Hack CE, Niessen HW. | title=Apoptosis in myocardial ischaemia and infarction | journal=J Clin Pathol | year=2002 | volume=55 | issue=11 | pages=801–11 | pmid=12401816 | doi = 10.1136/jcp.55.11.801}}</ref> As a result, the patient's heart will be permanently damaged. This scar tissue also puts the patient at risk for potentially life threatening arrhythmias, and may result in the formation of a ] that can rupture with catastrophic consequences.


] is also an important modifiable risk. Short-term exposure to air pollution such as ], ], and ] (but not ]) has been associated with MI and other acute cardiovascular events.<ref>{{cite journal | vauthors = Mustafic H, Jabre P, Caussin C, Murad MH, Escolano S, Tafflet M, Périer MC, Marijon E, Vernerey D, Empana JP, Jouven X | display-authors = 6 | title = Main air pollutants and myocardial infarction: a systematic review and meta-analysis | journal = JAMA | volume = 307 | issue = 7 | pages = 713–21 | date = February 2012 | pmid = 22337682 | doi = 10.1001/jama.2012.126 }}</ref> For sudden cardiac deaths, every increment of 30 units in Pollutant Standards Index correlated with an 8% increased risk of out-of-hospital cardiac arrest on the day of exposure.<ref>{{cite journal | vauthors = Ho AF, Wah W, Earnest A, Ng YY, Xie Z, Shahidah N, Yap S, Pek PP, Liu N, Lam SS, Ong ME | display-authors = 6 | title = Health impacts of the Southeast Asian haze problem – A time-stratified case crossover study of the relationship between ambient air pollution and sudden cardiac deaths in Singapore | journal = International Journal of Cardiology | volume = 271 | pages = 352–358 | date = November 2018 | pmid = 30223374 | doi = 10.1016/j.ijcard.2018.04.070 | s2cid = 52282745 }}</ref> Extremes of temperature are also associated.<ref>{{cite journal | vauthors = Sun Z, Chen C, Xu D, Li T | title = Effects of ambient temperature on myocardial infarction: A systematic review and meta-analysis | journal = Environmental Pollution | volume = 241 | pages = 1106–1114 | date = October 2018 | pmid = 30029319 | doi = 10.1016/j.envpol.2018.06.045 | bibcode = 2018EPoll.241.1106S | s2cid = 51705159 }}</ref>
Injured heart tissue conducts electrical impulses more slowly than normal heart tissue. The difference in conduction velocity between injured and uninjured tissue can trigger ] or a feedback loop that is believed to be the cause of many lethal arrhythmias. The most serious of these arrhythmias is ] (''V-Fib''/VF), an extremely fast and chaotic heart rhythm that is the leading cause of sudden cardiac death. Another life threatening arrhythmia is ] (''V-Tach''/VT), which may or may not cause sudden cardiac death. However, ventricular tachycardia usually results in rapid heart rates that prevent the heart from pumping blood effectively. ] and ] may fall to dangerous levels, which can lead to further coronary ischemia and extension of the infarct.


A number of acute and chronic ] including '']'', ], '']'', and '']'' among others have been linked to atherosclerosis and myocardial infarction.<ref name=Chat2012>{{cite journal | vauthors = Chatzidimitriou D, Kirmizis D, Gavriilaki E, Chatzidimitriou M, Malisiovas N | title = Atherosclerosis and infection: is the jury still not in? | journal = Future Microbiology | volume = 7 | issue = 10 | pages = 1217–30 | date = October 2012 | pmid = 23030426 | doi = 10.2217/fmb.12.87 }}</ref> Myocardial infarction can also occur as a late consequence of ].<ref name=Sanchez2014>{{cite journal | vauthors = Sánchez-Manubens J, Bou R, Anton J | title = Diagnosis and classification of Kawasaki disease | journal = Journal of Autoimmunity | volume = 48-49 | pages = 113–7 | date = February 2014 | pmid = 24485156 | doi = 10.1016/j.jaut.2014.01.010 }}</ref>
The ] is a device that was specifically designed to terminate these potentially fatal arrhythmias. The device works by delivering an electrical shock to the patient in order to depolarize a critical mass of the heart muscle, in effect "]ing" the heart. This therapy is time dependent, and the odds of successful defibrillation decline rapidly after the onset of cardiopulmonary arrest.


Calcium deposits in the coronary arteries can be detected with ]s. Calcium seen in coronary arteries can provide predictive information beyond that of classical risk factors.<ref>{{cite journal | vauthors = Hulten EA, Carbonaro S, Petrillo SP, Mitchell JD, Villines TC | title = Prognostic value of cardiac computed tomography angiography: a systematic review and meta-analysis | journal = Journal of the American College of Cardiology | volume = 57 | issue = 10 | pages = 1237–47 | date = March 2011 | pmid = 21145688 | doi = 10.1016/j.jacc.2010.10.011 | doi-access = free }}</ref> ] is associated with premature atherosclerosis;<ref>{{cite journal | vauthors = Clarke R, Halsey J, Bennett D, Lewington S | title = Homocysteine and vascular disease: review of published results of the homocysteine-lowering trials | journal = Journal of Inherited Metabolic Disease | volume = 34 | issue = 1 | pages = 83–91 | date = February 2011 | pmid = 21069462 | doi = 10.1007/s10545-010-9235-y | s2cid = 8714058 }}</ref> whether elevated homocysteine in the normal range is causal is controversial.<ref>{{cite journal | vauthors = Lonn E | title = Homocysteine in the prevention of ischemic heart disease, stroke and venous thromboembolism: therapeutic target or just another distraction? | journal = Current Opinion in Hematology | volume = 14 | issue = 5 | pages = 481–7 | date = September 2007 | pmid = 17934354 | doi = 10.1097/MOH.0b013e3282c48bd8 | s2cid = 8734056 }}</ref>
==Triggers==
Heart attack rates are higher in association with intense exertion, be it ] or ] exertion, especially if the exertion is more intense than the individual usually performs.<ref name="Framingham1998">Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. "". ''Circulation'' 1998; '''97'''(18): 1837-47. PMID 9603539</ref> Quantitatively, the period of intense exercise and subsequent recovery is associated with about a 6-fold higher myocardial infarction rate (compared with other more relaxed time frames) for people who are physically very fit.<ref name="Framingham1998">Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. "". ''Circulation'' 1998; '''97'''(18): 1837-47. PMID 9603539</ref> For those in poor physical condition, the rate differential is over 35-fold higher.<ref name="Framingham1998">Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. "". ''Circulation'' 1998; '''97'''(18): 1837-47. PMID 9603539</ref> One observed mechanism for this phenomenon is the increased arterial pulse pressure stretching and relaxation of arteries with each heart beat which, as has been observed with ], increases mechanical "shear stress" on ]s and the likelihood of plaque rupture.<ref name="Framingham1998">Wilson PW, D'Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB. "". ''Circulation'' 1998; '''97'''(18): 1837-47. PMID 9603539</ref>


In people without evident ], possible causes for the myocardial infarction are ] or ].<ref>{{cite journal | vauthors = Agewall S, Beltrame JF, Reynolds HR, Niessner A, Rosano G, Caforio AL, De Caterina R, Zimarino M, Roffi M, Kjeldsen K, Atar D, Kaski JC, Sechtem U, Tornvall P | display-authors = 6 | title = ESC working group position paper on myocardial infarction with non-obstructive coronary arteries | journal = European Heart Journal | volume = 38 | issue = 3 | pages = 143–153 | date = January 2017 | pmid = 28158518 | doi = 10.1093/eurheartj/ehw149 | doi-access = free }}</ref>
Acute severe infection, such as ], can trigger myocardial infarction. A more controversial link is that between '']'' infection and atherosclerosis.<ref name="Saikku-1992">{{cite journal | author=Saikku P, Leinonen M, Tenkanen L, Linnanmaki E, Ekman MR, Manninen V, Manttari M, Frick MH, Huttunen JK. | title=Chronic Chlamydia pneumoniae infection as a risk factor for coronary heart disease in the Helsinki Heart Study | journal=Ann Intern Med | year=1992 | volume=116 | issue=4 | pages=273–8 | pmid=1733381}}</ref> While this intracellular organism has been demonstrated in atherosclerotic plaques, evidence is inconclusive as to whether it can be considered a causative factor.<ref name="Saikku-1992">{{cite journal | author=Saikku P, Leinonen M, Tenkanen L, Linnanmaki E, Ekman MR, Manninen V, Manttari M, Frick MH, Huttunen JK. | title=Chronic Chlamydia pneumoniae infection as a risk factor for coronary heart disease in the Helsinki Heart Study | journal=Ann Intern Med | year=1992 | volume=116 | issue=4 | pages=273–8 | pmid=1733381}}</ref> Treatment with antibiotics in patients with proven atherosclerosis has not demonstrated a decreased risk of heart attacks or other coronary vascular diseases.<ref name="Andraws-2005">{{cite journal | author=Andraws R, Berger JS, Brown DL. | title=Effects of antibiotic therapy on outcomes of patients with coronary artery disease: a meta-analysis of randomized controlled trials | journal=JAMA | year=2005 | volume=293 | issue=21 | pages=2641–7 | pmid=15928286 | doi = 10.1001/jama.293.21.2641}}</ref>


== Mechanism ==
There is an association of an increased incidence of a heart attack in the morning hours, more specifically around 9 a.m. <ref name="pmid2865677">{{cite journal |author=Muller JE, Stone PH, Turi ZG, ''et al'' |title=Circadian variation in the frequency of onset of acute myocardial infarction |journal=] |volume=313 |issue=21 |pages=1315–22 |year=1985 |pmid=2865677 |doi=}}</ref><ref name="pmid3673917">{{cite journal |author=Beamer AD, Lee TH, Cook EF, ''et al'' |title=Diagnostic implications for myocardial ischemia of the circadian variation of the onset of chest pain |journal=] |volume=60 |issue=13 |pages=998–1002 |year=1987 |pmid=3673917 |doi=}}</ref><ref name="pmid9036740">{{cite journal |author=Cannon CP, McCabe CH, Stone PH, ''et al'' |title=Circadian variation in the onset of unstable angina and non-Q-wave acute myocardial infarction (the TIMI III Registry and TIMI IIIB) |journal=] |volume=79 |issue=3 |pages=253–8 |year=1997 |pmid=9036740 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0002914997007431}}</ref>. Some investigators have noticed that the ability of platelets to aggregate varies according to a circadian rhythm, although they have not proven causation.<ref name="pmid3587281">{{cite journal |author=Tofler GH, Brezinski D, Schafer AI, ''et al'' |title=Concurrent morning increase in platelet aggregability and the risk of myocardial infarction and sudden cardiac death |journal=] |volume=316 |issue=24 |pages=1514–8 |year=1987 |pmid=3587281 |doi=}}</ref> Some investigators theorize that this increased incidence may be related to the circadian variation in cortisol production affecting the concentrations of various cytokines and other mediators of inflammation.<ref name="pmid12027868">{{cite journal |author=Fantidis P, Perez De Prada T, Fernandez-Ortiz A, ''et al'' |title=Morning cortisol production in coronary heart disease patients |journal=] |volume=32 |issue=5 |pages=304–8 |year=2002 |pmid=12027868 |doi= |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0014-2972&date=2002&volume=32&issue=5&spage=304}}</ref>


=== Atherosclerosis ===
==Classification==
{{Further|Atherosclerosis}}
]s.<ref name="Alpert-2000">{{cite journal | author=Alpert JS, Thygesen K, Antman E, Bassand JP. | title=Myocardial infarction redefined--a consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the redefinition of myocardial infarction | journal=J Am Coll Cardiol | year=2000 | volume=36 | issue=3 | pages=959–69 | pmid=10987628 | doi=10.1016/S0735-1097(00)00804-4}}</ref>]]
] can lead to a heart attack and how blocked blood flow in a coronary artery can lead to a heart attack.]]
<!--Introduction-->The most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an ] supplying heart muscle.<ref name='ESC STEMI' /><ref name="Reed2017">{{cite journal | vauthors = Reed GW, Rossi JE, Cannon CP | title = Acute myocardial infarction | journal = Lancet | volume = 389 | issue = 10065 | pages = 197–210 | date = January 2017 | pmid = 27502078 | doi = 10.1016/S0140-6736(16)30677-8 | s2cid = 33523662 }}</ref> Plaques can become unstable, rupture, and additionally promote the formation of a ] that blocks the artery; this can occur in minutes. Blockage of an artery can lead to tissue death in tissue being supplied by that artery.<ref name=Davidsons2010B /> Atherosclerotic plaques are often present for decades before they result in symptoms.<ref name=Davidsons2010B>{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3085-7|edition=21st|pages=577–9}}</ref>


<!--Details-->The gradual buildup of ] and fibrous tissue in plaques in the wall of the ] or other arteries, typically over decades, is termed ].<ref name="pmid20065951">{{cite journal | vauthors = Woollard KJ, Geissmann F | title = Monocytes in atherosclerosis: subsets and functions | journal = Nature Reviews. Cardiology | volume = 7 | issue = 2 | pages = 77–86 | date = February 2010 | pmid = 20065951 | pmc = 2813241 | doi = 10.1038/nrcardio.2009.228 }}</ref> Atherosclerosis is characterized by progressive inflammation of the walls of the arteries.<ref name=Davidsons2010B /> Inflammatory cells, particularly ]s, move into affected arterial walls. Over time, they become laden with cholesterol products, particularly ], and become ]s. A ] forms as foam cells die. In response to ]s secreted by macrophages, ] and other cells move into the plaque and act to stabilize it. A stable plaque may have a thick fibrous cap with ]. If there is ongoing inflammation, the cap may be thin or ulcerate. Exposed to the pressure associated with blood flow, plaques, especially those with a thin lining, may rupture and trigger the formation of a blood clot (thrombus).<ref name=Davidsons2010B /> The cholesterol crystals have been associated with plaque rupture through mechanical injury and inflammation.<ref>{{cite journal | vauthors = Janoudi A, Shamoun FE, Kalavakunta JK, Abela GS | title = Cholesterol crystal induced arterial inflammation and destabilization of atherosclerotic plaque | journal = European Heart Journal | volume = 37 | issue = 25 | pages = 1959–67 | date = July 2016 | pmid = 26705388 | doi = 10.1093/eurheartj/ehv653 | doi-access = free }}</ref>
Acute myocardial infarction is a type of ], which is most frequently (but not always) a manifestation of ]. The acute coronary syndromes include ST segment elevation myocardial infarction (STEMI), non-ST segment elevation myocardial infarction (NSTEMI), and ] (UA).


=== {{Anchor|Other causes}} Other causes ===
===By zone===
Atherosclerotic disease is not the only cause of myocardial infarction, but it may exacerbate or contribute to other causes. A myocardial infarction may result from a heart with a limited blood supply subject to increased oxygen demands, such as in fever, ], ], ], or ]. Damage or failure of procedures such as ] (PCI) or ]s (CABG) may cause a myocardial infarction. Spasm of coronary arteries, such as ] may cause blockage.<ref name=THIRDDEF /><ref name=Harrisons2015 />
Depending on the location of the obstruction in the ], different zones of the heart can become injured. Using the ] corresponding to areas perfused by major coronary arteries, one can describe anterior, inferior, lateral, apical, septal, posterior, and right-ventricular infarctions (and combinations, such as anteroinferior, anterolateral, and so on).<ref name="MedicalDictionary">{{cite web | title=Dorland's Illustrated Medical Dictionary | publisher=WB Saunders, an Elsevier imprint | url=http://www.mercksource.com/pp/us/cns/cns_hl_dorlands.jspzQzpgzEzzSzppdocszSzuszSzcommonzSzdorlandszSzdorlandzSzdmd_i_07zPzhtm | dateformat=mdy | accessdate=November 25 2006}}</ref>


=== Tissue death ===
* For example, an occlusion of the ](LAD) will result in an ''anterior wall'' myocardial infarct.<ref name=rubin525>{{cite book | coauthors = Emanuel Rubin, Fred Gorstein, Raphael Rubin, Roland Schwarting, David Strayer | title = Rubin's Pathology - Clinicopathological Foundations of Medicine | publisher = Lippincott Williams & Wilkins | date = 2001 | location = Maryland | pages = 525 | isbn = 0-7817-4733-3 }}</ref>
]
If impaired blood flow to the heart lasts long enough, it triggers a process called the ]; the heart cells in the territory of the blocked coronary artery die (]), chiefly through ], and do not grow back. A ] ] forms in their place.<ref name=Davidsons2010B /> When an artery is blocked, cells lack ], needed to produce ] in ]. ATP is required for the maintenance of electrolyte balance, particularly through the ]. This leads to an ischemic cascade of intracellular changes, necrosis and ] of affected cells.<ref name="BUJA2005">{{cite journal | vauthors = Buja LM | title = Myocardial ischemia and reperfusion injury | journal = Cardiovascular Pathology | volume = 14 | issue = 4 | pages = 170–5 | date = July 2005 | pmid = 16009313 | doi = 10.1016/j.carpath.2005.03.006 }}</ref>


Cells in the area with the worst blood supply, just below the inner surface of the heart (]), are most susceptible to damage.<ref>{{cite journal | vauthors = Algranati D, Kassab GS, Lanir Y | title = Why is the subendocardium more vulnerable to ischemia? A new paradigm | journal = American Journal of Physiology. Heart and Circulatory Physiology | volume = 300 | issue = 3 | pages = H1090–100 | date = March 2011 | pmid = 21169398 | pmc = 3064294 | doi = 10.1152/ajpheart.00473.2010 }}</ref><ref name="BOLOOKI2010">{{cite web| vauthors = Bolooki HM, Askari A |title=Acute Myocardial Infarction |url= http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/cardiology/acute-myocardial-infarction/ |website=www.clevelandclinicmeded.com|access-date=24 May 2017 |date=August 2010 |url-status=live |archive-url=https://web.archive.org/web/20170428050921/http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/cardiology/acute-myocardial-infarction/|archive-date=28 April 2017}}</ref> Ischemia first affects this region, the ''subendocardial'' region, and tissue begins to die within 15–30 minutes of loss of blood supply.<ref name="AARONSON2013">{{cite book| vauthors = Aaronson PI, Ward JP, Connolly MJ |title=The cardiovascular system at a glance|date=2013|publisher=Wiley-Blackwell|location=Chichester, West Sussex|isbn=978-0-470-65594-8|pages=88–89|edition=4th}}</ref> The dead tissue is surrounded by a zone of potentially reversible ischemia that progresses to become a full-thickness ''transmural'' infarct.<ref name=BUJA2005 /><ref name=AARONSON2013 /> The initial "wave" of infarction can take place over 3–4 hours.<ref name=Davidsons2010B /><ref name=BUJA2005 /> These changes are seen on ] and cannot be predicted by the presence or absence of Q waves on an ECG.<ref name=BOLOOKI2010 /> The position, size and extent of an infarct depends on the affected artery, totality of the blockage, duration of the blockage, the presence of ], oxygen demand, and success of interventional procedures.<ref name=Harrisons2015 /><ref name=Reed2017 />
* Infarcts of the ''lateral wall'' are caused by occlusion of the ](LCx) or its oblique marginal branches (or even large diagonal branches from the LAD.)


Tissue death and ] alter the normal conduction pathways of the heart and weaken affected areas. The size and location put a person at risk of ] or ], ], ] following infarction, and rupture of the heart wall that can have catastrophic consequences.<ref name=Reed2017 /><ref name="Kutty2013">{{cite journal | vauthors = Kutty RS, Jones N, Moorjani N | title = Mechanical complications of acute myocardial infarction | journal = Cardiology Clinics | volume = 31 | issue = 4 | pages = 519–31, vii–viii | date = November 2013 | pmid = 24188218 | doi = 10.1016/j.ccl.2013.07.004 | type = Review }}</ref>
* Both ''inferior wall'' and ''posterior wall'' infarctions may be caused by occlusion of either the ] or the left circumflex artery, depending on which feeds the ].


Injury to the myocardium also occurs during re-perfusion. This might manifest as ventricular arrhythmia. The re-perfusion injury is a consequence of the calcium and sodium uptake from the cardiac cells and the release of oxygen radicals during reperfusion. No-reflow phenomenon—when blood is still unable to be distributed to the affected myocardium despite clearing the occlusion—also contributes to myocardial injury. Topical endothelial swelling is one of many factors contributing to this phenomenon.<ref name=KlonerHale>{{cite book| vauthors = Kloner R, Hale SL |chapter = Reperfusion Injury: Prevention and Management|pages=286–288| veditors = Morrow DA |title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}</ref>
* Right ''ventricular wall'' infarcts are also caused by ] occlusion.


== Diagnosis ==
===Subendocardial vs. transmural===
{{Main|Diagnosis of myocardial infarction}}
Another distinction is whether a MI is subendocardial, affecting only the inner third to one half of the heart muscle, or transmural, damaging (almost) the entire wall of the heart.<ref name=rubin's-p545>{{cite book | coauthors = Emanuel Rubin, Fred Gorstein, Raphael Rubin, Roland Schwarting, David Strayer | title = Rubin's Pathology - Clinicopathological Foundations of Medicine | publisher = Lippincott Williams & Wilkins | date = 2001 | location = Maryland | pages = 545 | isbn = 0-7817-4733-3 }}</ref> The inner part of the heart muscle is more vulnerable to oxygen shortage, because the coronary arteries run inward from the ] to the ], and because the blood flow through the heart muscle is hindered by the ].<ref name=rubin525/>


=== Criteria ===
The phrases transmural and subendocardial infarction were previously considered synonymous with Q-wave and non-Q-wave myocardial infarction respectively, based on the presence or absence of Q waves on the ECG. It has since been shown that there is no clear ] between the presence of Q waves with a transmural infarction and the absence of Q waves with a subendocardial infarction,<ref name="Moon-2004">{{cite journal | author=Moon JC, De Arenaza DP, Elkington AG, Taneja AK, John AS, Wang D, Janardhanan R, Senior R, Lahiri A, Poole-Wilson PA, Pennell DJ. | title=The pathologic basis of Q-wave and non-Q-wave myocardial infarction: a cardiovascular magnetic resonance study | journal=J Am Coll Cardiol | year=2004 | volume=44 | issue=3 | pages=554–60 | pmid=15358019 | doi = 10.1016/j.jacc.2004.03.076}}</ref> but Q waves are associated with larger infarctions, while the lack of Q waves is associated with smaller infarctions. The presence or absence of Q-waves also has clinical importance,<ref name="Yang-2004">{{cite journal | author=Yang H, Pu M, Rodriguez D, Underwood D, Griffin BP, Kalahasti V, Thomas JD, Brunken RC | title=Ischemic and viable myocardium in patients with non-Q-wave or Q-wave myocardial infarction and left ventricular dysfunction: a clinical study using positron emission tomography, echocardiography, and electrocardiography | journal=J Am Coll Cardiol | year=2004 | volume=43 | issue=4 | pages=592–8 | pmid=14975469 | doi = 10.1016/j.jacc.2003.07.052}}</ref> with improved outcomes associated with a lack of Q waves.<ref name="Goodman-1998">{{cite journal | author=Goodman SG, Langer A, Ross AM, Wildermann NM, Barbagelata A, Sgarbossa EB, Wagner GS, Granger CB, Califf RM, Topol EJ, Simoons ML, Armstrong PW. | title=Non-Q-wave versus Q-wave myocardial infarction after thrombolytic therapy: angiographic and prognostic insights from the global utilization of streptokinase and tissue plasminogen activator for occluded coronary arteries-I angiographic substudy. GUSTO-I Angiographic Investigators | journal=Circulation | year=1998 | volume=97 | issue=5 | pages=444–50 | pmid=9490238}}</ref>
] by the two major blood vessels, the ] and ] (labelled LCA and RCA). A myocardial infarction (2) has occurred with blockage of a branch of the left coronary artery (1).]]
A myocardial infarction, according to current consensus, is defined by elevated cardiac ] with a rising or falling trend and at least one of the following:<ref>{{cite journal | vauthors = Thygesen K, Alpert JS, Jaffe AS, Chaitman BR, Bax JJ, Morrow DA, White HD | title = Fourth universal definition of myocardial infarction (2018) | journal = European Heart Journal | volume = 40 | issue = 3 | pages = 237–269 | date = January 2019 | pmid = 30165617 | doi = 10.1093/eurheartj/ehy462 | doi-access = free | hdl = 10044/1/73052 | hdl-access = free }}</ref>
* Symptoms relating to ischemia
* Changes on an ] (ECG), such as ] changes, new ], or pathologic ]
* Changes in the motion of the heart wall on imaging
* Demonstration of a thrombus on ] or at ].


=== {{Anchor|STEMI}}{{Anchor|NSTEMI}}Types ===
==Symptoms==
{{See also|Electrocardiography in myocardial infarction}}{{Redirect|STEMI|the Christian evangelist organization|Stephen Tong#Ministry}}
]
A myocardial infarction is usually clinically classified as an ST-elevation MI (STEMI) or a non-ST elevation MI (NSTEMI). These are based on ], a portion of a heartbeat graphically recorded on an ].<ref name=THIRDDEF /> STEMIs make up about 25–40% of myocardial infarctions.<ref name=AHA2013 /> A more explicit classification system, based on international consensus in 2012, also exists. This classifies myocardial infarctions into five types:<ref name=THIRDDEF />
]
# Spontaneous MI related to plaque erosion and/or rupture fissuring, or dissection
# MI related to ischemia, such as from increased oxygen demand or decreased supply, e.g., coronary artery spasm, coronary embolism, anemia, arrhythmias, high blood pressure, or low blood pressure
# Sudden unexpected cardiac death, including cardiac arrest, where symptoms may suggest MI, an ECG may be taken with suggestive changes, or a blood clot is found in a coronary artery by angiography and/or at autopsy, but where blood samples could not be obtained, or at a time before the appearance of cardiac biomarkers in the blood
# Associated with ] or ]s
#* Associated with ] (PCI)
#* Associated with stent thrombosis as documented by angiography or at autopsy
# Associated with ]
# Associated with ] in young, fit women


=== Cardiac biomarkers ===
The onset of symptoms in myocardial infarction (MI) is usually gradual, over several minutes, and rarely instantaneous.<ref name=warningsigns>]. . Retrieved November 22, 2006.</ref> ] is the most common symptom of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Chest pain due to ] (a lack of blood and hence oxygen supply) of the heart muscle is termed ]. Pain radiates most often to the left ], but may also radiate to the lower ], ], right arm, ], and ], where it may mimic ]. ], in which the patient localizes the chest pain by clenching their fist over the ], has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed that it had a poor positive predictive value.<ref name="pmid17208083">{{cite journal |author=Marcus GM, Cohen J, Varosy PD, ''et al'' |title=The utility of gestures in patients with chest discomfort |journal=] |volume=120 |issue=1 |pages=83–9 |year=2007 |pmid=17208083 |doi=10.1016/j.amjmed.2006.05.045 |url=http://linkinghub.elsevier.com/retrieve/pii/S0002-9343(06)00668-1}}</ref>
<!--Troponin-->
There are many different ]s used to determine the presence of cardiac muscle damage. ]s, measured through a blood test, are considered to be the best,<ref name=AHA2013 /> and are preferred because they have greater ] for measuring injury to the heart muscle than other tests.<ref name="Reed2017" /> A rise in troponin occurs within 2–3 hours of injury to the heart muscle, and peaks within 1–2 days. The level of the troponin, as well as a change over time, are useful in measuring and diagnosing or excluding myocardial infarctions, and the diagnostic accuracy of troponin testing is improving over time.<ref name="Reed2017" /> One high-sensitivity cardiac troponin can rule out a heart attack as long as the ECG is normal.<ref>{{cite journal | vauthors = Pickering JW, Than MP, Cullen L, Aldous S, Ter Avest E, Body R, Carlton EW, Collinson P, Dupuy AM, Ekelund U, Eggers KM, Florkowski CM, Freund Y, George P, Goodacre S, Greenslade JH, Jaffe AS, Lord SJ, Mokhtari A, Mueller C, Munro A, Mustapha S, Parsonage W, Peacock WF, Pemberton C, Richards AM, Sanchis J, Staub LP, Troughton R, Twerenbold R, Wildi K, Young J | display-authors = 6 | title = Rapid Rule-out of Acute Myocardial Infarction With a Single High-Sensitivity Cardiac Troponin T Measurement Below the Limit of Detection: A Collaborative Meta-analysis | journal = Annals of Internal Medicine | volume = 166 | issue = 10 | pages = 715–724 | date = May 2017 | pmid = 28418520 | doi = 10.7326/M16-2562 | url = https://www.research.manchester.ac.uk/portal/en/publications/rapid-ruleout-of-acute-myocardial-infarction-with-a-single-highsensitivity-cardiac-troponin-t-measurement-below-the-limit-of-detection(0e2cb8e0-229a-446b-9389-7fa319a649d4).html }}</ref><ref>{{cite journal | vauthors = Chapman AR, Lee KK, McAllister DA, Cullen L, Greenslade JH, Parsonage W, Worster A, Kavsak PA, Blankenberg S, Neumann J, Sörensen NA, Westermann D, Buijs MM, Verdel GJ, Pickering JW, Than MP, Twerenbold R, Badertscher P, Sabti Z, Mueller C, Anand A, Adamson P, Strachan FE, Ferry A, Sandeman D, Gray A, Body R, Keevil B, Carlton E, Greaves K, Korley FK, Metkus TS, Sandoval Y, Apple FS, Newby DE, Shah AS, Mills NL | display-authors = 6 | title = Association of High-Sensitivity Cardiac Troponin I Concentration With Cardiac Outcomes in Patients With Suspected Acute Coronary Syndrome | journal = JAMA | volume = 318 | issue = 19 | pages = 1913–1924 | date = November 2017 | pmid = 29127948 | pmc = 5710293 | doi = 10.1001/jama.2017.17488 }}</ref>


<!--Other tests-->
Shortness of breath (]) occurs when the damage to the heart limits the ] of the ], causing ] and consequent ]. Other symptoms include ] (an excessive form of ]), weakness, ], ], ], and ]s. These symptoms are likely induced by a massive surge of ] from the ]<ref name="pmid3524599">{{cite journal |author=Little RA, Frayn KN, Randall PE, ''et al'' |title=Plasma catecholamines in the acute phase of the response to myocardial infarction |journal=] |volume=3 |issue=1 |pages=20–7 |year=1986 |pmid=3524599 |doi=}}</ref> which occurs in response to pain and the hemodynamic abnormalities that result from cardiac dysfunction. ] (due to inadequate cerebral perfusion and cardiogenic shock) and even ] (frequently due to the development of ventricular fibrillation) can occur in myocardial infarctions.
Other tests, such as ] or ], are discouraged.<ref name=AHANSTEMI2014>{{cite journal | vauthors = Amsterdam EA, Wenger NK, Brindis RG, Casey DE, Ganiats TG, Holmes DR, Jaffe AS, Jneid H, Kelly RF, Kontos MC, Levine GN, Liebson PR, Mukherjee D, Peterson ED, Sabatine MS, Smalling RW, Zieman SJ | display-authors = 6 | title = 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines | journal = Circulation | volume = 130 | issue = 25 | pages = e344–426 | date = December 2014 | pmid = 25249585 | doi = 10.1161/CIR.0000000000000134 | doi-access = free }}</ref> CK-MB is not as specific as troponins for acute myocardial injury, and may be elevated with past cardiac surgery, inflammation or electrical cardioversion; it rises within 4–8 hours and returns to normal within 2–3 days.<ref name=Harrisons2015 /> ] may be useful to rule out MI rapidly when used along with troponin.<ref>{{cite journal | vauthors = Lipinski MJ, Escárcega RO, D'Ascenzo F, Magalhães MA, Baker NC, Torguson R, Chen F, Epstein SE, Miró O, Llorens P, Giannitsis E, Lotze U, Lefebvre S, Sebbane M, Cristol JP, Chenevier-Gobeaux C, Meune C, Eggers KM, Charpentier S, Twerenbold R, Mueller C, Biondi-Zoccai G, Waksman R | display-authors = 6 | title = A systematic review and collaborative meta-analysis to determine the incremental value of copeptin for rapid rule-out of acute myocardial infarction | journal = The American Journal of Cardiology | volume = 113 | issue = 9 | pages = 1581–91 | date = May 2014 | pmid = 24731654 | doi = 10.1016/j.amjcard.2014.01.436 }}</ref>


=== Electrocardiogram ===
Women and older patients experience atypical symptoms more frequently than their male and younger counterparts.<ref name="ACSwomen">{{cite journal |author=Canto JG, Goldberg RJ, Hand MM, ''et al'' |title=Symptom presentation of women with acute coronary syndromes: myth vs reality |journal=Arch. Intern. Med. |volume=167 |issue=22 |pages=2405–13 |year=2007 |month=December |pmid=18071161 |doi=10.1001/archinte.167.22.2405 |url=http://archinte.ama-assn.org/cgi/pmidlookup?view=long&pmid=18071161}}</ref> Women also have more symptoms compared to men (2.6 on average vs 1.8 symptoms in men).<ref name="ACSwomen"/> The most common symptoms of MI in women include ], weakness, and ]. Fatigue, sleep disturbances, and dyspnea have been reported as frequently occurring symptoms which may manifest as long as one month before the actual clinically manifested ischemic event. In women, ] may be less predictive of coronary ] than in men.<ref name=McSweeney>{{cite journal | author=McSweeney JC, Cody M, O'Sullivan P, Elberson K, Moser DK, Garvin BJ | title=Women's early warning symptoms of acute myocardial infarction | journal=Circulation | year=2003 | pages=2619–23 | volume=108 | issue=21 | pmid=14597589 | doi = 10.1161/01.CIR.0000097116.29625.7C}}</ref>
]. Elevation of the ] can be seen in leads II, III and aVF.]]
]s (ECGs) are a series of leads placed on a person's chest that measure electrical activity associated with contraction of the heart muscle.<ref name=Davidsons2010C /> The taking of an ECG is an important part of the workup of an AMI,<ref name=THIRDDEF /> and ECGs are often not just taken once but may be repeated over minutes to hours, or in response to changes in signs or symptoms.<ref name=THIRDDEF />


ECG readouts produce a waveform with different labeled features.<ref name=Davidsons2010C>{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3085-7|edition=21st|pages=529–30}}</ref> In addition to a rise in biomarkers, a rise in the ], changes in the shape or flipping of ]s, new ], or a new ] can be used to diagnose an AMI.<ref name=THIRDDEF /> In addition, ] can be used to diagnose an ST segment myocardial infarction (STEMI). A rise must be new in V2 and V3 ≥2&nbsp;mm (0,2 mV) for males or ≥1.5&nbsp;mm (0.15 mV) for females or ≥1&nbsp;mm (0.1&nbsp;mV) in two other ].<ref name=AHA2013 /><ref name=THIRDDEF /> ST elevation is associated with infarction, and may be preceded by changes indicating ischemia, such as ST depression or inversion of the T waves.<ref name=Davidsons2010C /> Abnormalities can help differentiate the location of an infarct, based on the leads that are affected by changes.<ref name=Davidsons2010 /> Early STEMIs may be preceded by peaked T waves.<ref name=AHA2013 /> Other ECG abnormalities relating to complications of acute myocardial infarctions may also be evident, such as ] or ].<ref>{{Cite book|title=Harrison's principles of internal medicine| vauthors = Kasper DL, Fauci AS, Hauser SL, Longo DL, Jameson JL, Loscalzo J |publisher=McGraw Hill Education |year=2015 |isbn=978-0-07-180215-4 |pages=1457 |oclc=923181481}}</ref>
Approximately half of all MI patients have experienced warning symptoms such as chest pain prior to the infarction.<ref name=MedicineNet>D Lee, D Kulick, J Marks. by MedicineNet.com . Retrieved November 28, 2006.</ref>


=== Imaging ===
Approximately one fourth of all myocardial infarctions are silent, without chest pain or other symptoms.<ref name="Kannel-1986">{{cite journal | author=Kannel WB. | title=Silent myocardial ischemia and infarction: insights from the Framingham Study | journal=Cardiol Clin | year=1986 | volume=4 | issue=4| pages=583–91 | pmid=3779719}}</ref> These cases can be discovered later on electrocardiograms or at autopsy without a prior history of related complaints. A silent course is more common in the ], in patients with ]<ref name="Diabetologica2004-David">{{cite journal | author=Davis TM, Fortun P, Mulder J, Davis WA, Bruce DG | title=Silent myocardial infarction and its prognosis in a community-based cohort of Type 2 diabetic patients: the Fremantle Diabetes Study | journal=Diabetologia | year=2004 | pages=395–9 | volume=47 | issue=3 | pmid=14963648 | doi = 10.1007/s00125-004-1344-4}} </ref> and after ], probably because the ] heart is not connected to nerves of the host.<ref name=rubin's>{{cite book | coauthors = Emanuel Rubin, Fred Gorstein, Raphael Rubin, Roland Schwarting, David Strayer | title = Rubin's Pathology - Clinicopathological Foundations of Medicine | publisher = Lippincott Williams & Wilkins | date = 2001 | location = Maryland | pages = 549 | isbn = 0-7817-4733-3 }}</ref> In diabetics, differences in ], ], and ] factors have been cited as possible explanations for the lack of symptoms.<ref name="Diabetologica2004-David"/>
]
Noninvasive imaging plays an important role in the diagnosis and characterisation of myocardial infarction.<ref name=THIRDDEF /> Tests such as ]s can be used to explore and exclude alternate causes of a person's symptoms.<ref name=THIRDDEF /> ] may assist in modifying clinical suspicion of ongoing myocardial infarction in patients that can't be ruled out or ruled in following initial ] and ] testing.<ref name="auto">{{cite journal | vauthors = Collet JP, Thiele H, Barbato E, Barthélémy O, Bauersachs J, Bhatt DL, Dendale P, Dorobantu M, Edvardsen T, Folliguet T, Gale CP, Gilard M, Jobs A, Jüni P, Lambrinou E, Lewis BS, Mehilli J, Meliga E, Merkely B, Mueller C, Roffi M, Rutten FH, Sibbing D, Siontis GC | display-authors = 6 | title = 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation | journal = European Heart Journal | volume = 42 | issue = 14 | pages = 1289–1367 | date = April 2021 | pmid = 32860058 | doi = 10.1093/eurheartj/ehaa575 | doi-access = free }}</ref> ] has no role in the acute diagnostic algorithm; however, it can confirm a clinical suspicion of Chronic Coronary Syndrome when the patient's history, ] (including ]) ECG, and cardiac biomarkers suggest coronary artery disease.<ref name="WISELY2017" />


], an ] scan of the heart, is able to visualize the heart, its size, shape, and any abnormal motion of the heart walls as they beat that may indicate a myocardial infarction. The flow of blood can be imaged, and ]s may be given to improve image.<ref name=THIRDDEF /> Other scans using ] contrast include ] ] using ], ] (]s) or ]; or a ] using ] or ].<ref name=THIRDDEF /> These ] scans can visualize the perfusion of heart muscle.<ref name=THIRDDEF /> SPECT may also be used to determine viability of tissue, and whether areas of ischemia are inducible.<ref name=THIRDDEF /><ref>{{cite journal | vauthors = Schinkel AF, Valkema R, Geleijnse ML, Sijbrands EJ, Poldermans D | title = Single-photon emission computed tomography for assessment of myocardial viability | journal = EuroIntervention | volume = 6 | issue = Supplement G | pages = G115–22 | date = May 2010 | pmid = 20542817 }}</ref>
Any group of symptoms compatible with a sudden interruption of the blood flow to the heart are called an ].<ref name=ACS>. ]. Retrieved November 25, 2006.</ref>


Medical societies and professional guidelines recommend that the physician confirm a person is at high risk for Chronic Coronary Syndrome before conducting diagnostic non-invasive imaging tests to make a diagnosis,<ref name="WISELY2017">{{cite web|title=American College of Cardiology|url=http://www.choosingwisely.org/societies/american-college-of-cardiology/|website=www.choosingwisely.org|publisher=Choosing Wisely|access-date=24 May 2017|date=28 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170728125746/http://www.choosingwisely.org/societies/american-college-of-cardiology/|archive-date=28 July 2017}}</ref><ref name=NICECG94>{{NICE|cg94|Unstable angina and NSTEMI|2010}}</ref><ref name="auto"/> as such tests are unlikely to change management and result in increased costs.<ref name="WISELY2017" /> Patients who have a normal ECG and who are able to exercise, for example, most likely do not merit routine imaging.<ref name="WISELY2017" />
The ] includes other catastrophic causes of chest pain, such as ], ], ] causing ], ], and ].<ref name="pmid16199332">{{cite journal |author=Boie ET |title=Initial evaluation of chest pain |journal=] |volume=23 |issue=4 |pages=937–57 |year=2005 |pmid=16199332 |doi=10.1016/j.emc.2005.07.007 |url=http://linkinghub.elsevier.com/retrieve/pii/S0733-8627(05)00059-3}}</ref>


<gallery widths="200px" heights="200px">
==Diagnosis==
File:UOTW 36 - Ultrasound of the Week 1.webm|Poor movement of the heart due to an MI as seen on ultrasound<ref name=UOTW36>{{cite web|title=UOTW #36 – Ultrasound of the Week|url=https://www.ultrasoundoftheweek.com/uotw-36/|website=Ultrasound of the Week|access-date=27 May 2017|date=5 February 2015|url-status=live|archive-url=https://web.archive.org/web/20170509115806/https://www.ultrasoundoftheweek.com/uotw-36/|archive-date=9 May 2017}}</ref>
The diagnosis of myocardial infarction is made by integrating the history of the presenting illness and physical examination with ] findings and ]s (]s for ] ] damage).<ref name=GPnotebook_MI> - ], retrieved November 27, 2006.</ref> A ] allows visualization of narrowings or obstructions on the heart vessels, and therapeutic measures can follow immediately. At ], a ] can diagnose a myocardial infarction based on ] findings.
File:UOTW 36 - Ultrasound of the Week 2.webm|Pulmonary edema due to an MI as seen on ultrasound<ref name=UOTW36 />
</gallery>


=== Differential diagnosis ===
A ] and routine blood tests may indicate complications or precipitating causes and are often performed upon arrival to an ]. New regional wall motion abnormalities on an ] are also suggestive of a myocardial infarction. Echo may be performed in equivocal cases by the on-call cardiologist.<ref name=eMedicineEMERG>''DE Fenton et al.'' - ], retrieved November 27, 2006.</ref> In stable patients whose symptoms have resolved by the time of evaluation, ] (Tc99m MIBI) or ] can be used in ] to visualize areas of reduced blood flow in conjunction with physiologic or pharmocologic stress.<ref name=eMedicineEMERG/><ref name=heartscanpage> - Patient information from ]. Retrieved November 27, 2006.</ref> Thallium may also be used to determine viability of tissue, distinguishing whether non-functional myocardium is actually dead or merely in a state of hibernation or of being stunned.<ref name="pmid9885104">{{cite journal |author=Skoufis E, McGhie AI |title=Radionuclide techniques for the assessment of myocardial viability |journal=] |volume=25 |issue=4 |pages=272–9 |year=1998 |pmid=9885104 |doi=}}</ref>
There are many causes of ], which can originate from the heart, ]s, ], ], and other muscles, bones and nerves surrounding the chest.<ref name=Davidsons2010D /> In addition to myocardial infarction, other causes include ], insufficient blood supply (]) to the heart muscles without evidence of cell death, ]; ], tumors of the lungs, ], ], ], ] and other musculoskeletal injuries.<ref name="Davidsons2010D">{{cite book | vauthors = Colledge NR, Walker BR, Ralston SH, Davidson LS |title=Davidson's principles and practice of medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3085-7|edition=21st|pages=535, 539}}</ref><ref name="THIRDDEF" /> Rarer severe differential diagnoses include ], ], ], and ] causing ].<ref name="pmid16199332">{{cite journal | vauthors = Boie ET | title = Initial evaluation of chest pain | journal = Emergency Medicine Clinics of North America | volume = 23 | issue = 4 | pages = 937–57 | date = November 2005 | pmid = 16199332 | doi = 10.1016/j.emc.2005.07.007 }}</ref> The chest pain in an MI may mimic ].<ref name='ESC STEMI' /> Causes of sudden-onset ] generally involve the lungs or heart – including ], pneumonia, ] reactions and ], and pulmonary embolus, ] and ].<ref name=Davidsons2010D /> There are many different causes of fatigue, and myocardial infarction is not a common cause.<ref>{{cite web|title=Assessment of fatigue|url=http://bestpractice.bmj.com/best-practice/monograph/571/diagnosis/differential-diagnosis.html|website=BMJ Best Practice|access-date=6 June 2017|date=17 August 2016|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828180811/https://bestpractice.bmj.com/topics/en-gb/571/differentials|url-status=dead}}</ref>


== Prevention ==
===Diagnostic criteria===
There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as ] after an initial myocardial infarction,<ref name=Reed2017 /> because of shared risk factors and an aim to reduce atherosclerosis affecting heart vessels.<ref name=Harrisons2015 /> The ] also appear to protect against myocardial infarction with a benefit of 15 to 45%.<ref>{{cite journal | vauthors = MacIntyre CR, Mahimbo A, Moa AM, Barnes M | title = Influenza vaccine as a coronary intervention for prevention of myocardial infarction | journal = Heart | volume = 102 | issue = 24 | pages = 1953–1956 | date = December 2016 | pmid = 27686519 | pmc = 5256393 | doi = 10.1136/heartjnl-2016-309983 }}</ref>
WHO criteria<ref name=Gillum>Gillum RF, Fortmann SP, Prineas RJ, Kottke TE. International diagnostic criteria for acute myocardial infarction and acute stroke. ''Am Heart J'' 1984;108:150-8. PMID 6731265</ref> have classically been used to diagnose MI; a patient is diagnosed with myocardial infarction if two (probable) or three (definite) of the following criteria are satisfied:
# Clinical history of ischaemic type chest pain lasting for more than 20 minutes
# Changes in serial ECG tracings
# Rise and fall of serum cardiac biomarkers such as ]-MB fraction and ]


=== Primary prevention ===
The WHO criteria were refined in 2000 to give more prominence to cardiac biomarkers.<ref name="Alpert-2000"/> According to the new guidelines, a cardiac ] rise accompanied by either typical symptoms, pathological Q waves, ST elevation or depression or coronary intervention are diagnostic of MI.
==== Lifestyle ====
Physical activity can reduce the risk of cardiovascular disease, and people at risk are advised to engage in 150 minutes of moderate or 75 minutes of vigorous intensity ] a week.<ref name=NICECG181 /> Keeping a healthy weight, drinking alcohol within the recommended limits, and ] reduce the risk of cardiovascular disease.<ref name=NICECG181 />


<!--Diet-->Substituting ]s such as ] and ] instead of saturated fats may reduce the risk of myocardial infarction,<ref name=":1" /> although there is not universal agreement.<ref name=Chow2014 /> Dietary modifications are recommended by some national authorities, with recommendations including increasing the intake of wholegrain starch, reducing sugar intake (particularly of refined sugar), consuming five portions of fruit and vegetables daily, consuming two or more portions of fish per week, and consuming 4–5 portions of unsalted ], ]s, or ]s per week.<ref name=NICECG181 /> The dietary pattern with the greatest support is the ].<ref>{{cite journal | vauthors = Stradling C, Hamid M, Taheri S, Thomas GN | title = A review of dietary influences on cardiovascular health: part 2: dietary patterns | journal = Cardiovascular & Hematological Disorders Drug Targets | volume = 14 | issue = 1 | pages = 50–63 | date = 2014 | pmid = 24993125 | doi = 10.2174/1871529x14666140701095426 }}</ref> ]s and mineral supplements are of no proven benefit,<ref>{{cite journal | vauthors = Fortmann SP, Burda BU, Senger CA, Lin JS, Whitlock EP | title = Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer: An updated systematic evidence review for the U.S. Preventive Services Task Force | journal = Annals of Internal Medicine | volume = 159 | issue = 12 | pages = 824–34 | date = December 2013 | pmid = 24217421 | doi = 10.7326/0003-4819-159-12-201312170-00729 | s2cid = 17366251 }}</ref> and neither are plant ]s or ].<ref name=NICECG181>{{NICE|181|Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease|2014}}</ref>
===Physical examination===
The general appearance of patients may vary according to the experienced symptoms; the patient may be comfortable, or restless and in severe distress with an increased ]. A cool and ] is common and points to ]. Some patients have low-grade fever (38–39 °C). ] may be elevated or decreased, and the ] can be become ].<ref name=emedicine>S. Garas ''et al.''. . ]. Retrieved November 22, 2006.</ref><ref name=harrisons-p1444>Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL. ''Harrison's Principles of Internal Medicine''. p. 1444. New York: McGraw-Hill, 2005. ISBN 0-07-139140-1.</ref>


] measures may also act at a population level to reduce the risk of myocardial infarction, for example by reducing unhealthy diets (excessive salt, saturated fat, and trans-fat) including food labeling and marketing requirements as well as requirements for catering and restaurants and stimulating physical activity. This may be part of regional cardiovascular disease prevention programs or through the ] of regional and local plans and policies.<ref name=NICEPH25>{{cite web | vauthors=McPherson K, et al. | title=Prevention of cardiovascular disease – NICE public health guidance 25 | publisher=] | location=London | date=June 2010 | url=http://guidance.nice.org.uk/ph25 | url-status=live | archive-url=https://web.archive.org/web/20140329171156/http://guidance.nice.org.uk/PH25 | archive-date=2014-03-29 }}</ref>
If heart failure ensues, elevated ] and ], or swelling of the legs due to peripheral ] may be found on inspection. Rarely, a cardiac bulge with a pace different from the pulse rhythm can be felt on ]. Various abnormalities can be found on ], such as a third and fourth ], ], paradoxical splitting of the second heart sound, a ] friction rub and ] over the lung.<ref name=emedicine/><ref name=harrisons-p1450>Kasper DL, ''et al.'' ''Harrison's Principles of Internal Medicine''. p. 1450.</ref>


Most guidelines recommend combining different preventive strategies. A 2015 Cochrane Review found some evidence that such an approach might help with&nbsp;],&nbsp;]&nbsp;and&nbsp;]. However, there was insufficient evidence to show an effect on mortality or actual cardio-vascular events.<ref>{{cite journal | vauthors = Ebrahim S, Taylor F, Ward K, Beswick A, Burke M, Davey Smith G | title = Multiple risk factor interventions for primary prevention of coronary heart disease | journal = The Cochrane Database of Systematic Reviews | issue = 1 | pages = CD001561 | date = January 2011 | pmid = 21249647 | pmc = 4160097 | doi = 10.1002/14651858.cd001561.pub3 }}</ref>
] showing ST-segment elevation (orange) in I, aVL and V1-V5 with reciprocal changes (blue) in the inferior leads, indicative of an anterior wall myocardial infarction.]]
] (ECG) showing acute inferior ST segment elevation MI (STEMI). Note the ST segment elevation in leads II, III, and aVF along with reciprocal ST segment depression in leads I and aVL.]]


===Electrocardiogram=== ==== Medication ====
]s, drugs that act to lower blood cholesterol, decrease the incidence and mortality rates of myocardial infarctions.<ref>{{cite journal | vauthors = Taylor F, Huffman MD, Macedo AF, Moore TH, Burke M, Davey Smith G, Ward K, Ebrahim S | display-authors = 6 | title = Statins for the primary prevention of cardiovascular disease | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD004816 | date = January 2013 | pmid = 23440795 | pmc = 6481400 | doi = 10.1002/14651858.CD004816.pub5 }}</ref> They are often recommended in those at an elevated risk of cardiovascular diseases.<ref name=NICECG181 />
{{main|Electrocardiogram}}
The primary purpose of the ] is to detect ] or acute coronary injury in broad, symptomatic ] populations. However, the standard 12 lead ] has several limitations. An ] represents a brief sample in time. Because unstable ischemic syndromes have rapidly changing supply versus demand characteristics, a single ECG may not accurately represent the entire picture.<ref name=Cannon_175>Cannon CP at al. ''Management of Acute Coronary Syndromes''. p. 175. New Jersey: Humana Press, 1999. ISBN 0-89603-552-2.</ref> It is therefore desirable to obtain ''serial'' 12 lead ECGs, particularly if the first ECG is obtained during a pain-free episode. Alternatively, many ]s and ]s use computers capable of continuous ST segment monitoring.<ref name="NHAAP_1997">{{cite journal |author=Selker HP, Zalenski RJ, Antman EM, ''et al'' |title=An evaluation of technologies for identifying acute cardiac ischemia in the emergency department: executive summary of a National Heart Attack Alert Program Working Group Report |journal=Ann Emerg Med |volume=29 |issue=1 |pages=1–12 |year=1997 |month=January |pmid=8998085 |doi=10.1016/S0196-0644(97)70297-X}}</ref> The standard 12 lead ECG also does not directly examine the ], and is relatively poor at examining the posterior basal and lateral walls of the ]. In particular, acute myocardial infarction in the distribution of the circumflex artery is likely to produce a nondiagnostic ECG.<ref name=Cannon_175/> The use of additional ECG leads like right-sided leads V3R and V4R and posterior leads V7, V8, and V9 may improve sensitivity for right ventricular and posterior myocardial infarction. In spite of these limitations, the 12 lead ECG stands at the center of risk stratification for the patient with suspected acute myocardial infarction. Mistakes in interpretation are relatively common, and the failure to identify high risk features has a negative effect on the quality of patient care.<ref name="EDQMI_2006">{{cite journal |author=Masoudi FA, Magid DJ, Vinson DR, ''et al'' |title=Implications of the failure to identify high-risk electrocardiogram findings for the quality of care of patients with acute myocardial infarction: results of the Emergency Department Quality in Myocardial Infarction (EDQMI) study |journal=Circulation |volume=114 |issue=15 |pages=1565–71 |year=2006 |month=October |pmid=17015790 |doi=10.1161/CIRCULATIONAHA.106.623652 |url=http://circ.ahajournals.org/cgi/content/full/114/15/1565}}</ref>


] has been studied extensively in people considered at increased risk of myocardial infarction. Based on numerous studies in different groups (e.g. people with or without diabetes), there does not appear to be a benefit strong enough to outweigh the risk of excessive bleeding.<ref name=ATTaspirin2009>{{cite journal | vauthors = Baigent C, Blackwell L, Collins R, Emberson J, Godwin J, Peto R, Buring J, Hennekens C, Kearney P, Meade T, Patrono C, Roncaglioni MC, Zanchetti A | display-authors = 6 | title = Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials | journal = Lancet | volume = 373 | issue = 9678 | pages = 1849–60 | date = May 2009 | pmid = 19482214 | pmc = 2715005 | doi = 10.1016/S0140-6736(09)60503-1 }}</ref><ref>{{cite journal|display-authors=6|vauthors=Sutcliffe P, Connock M, Gurung T, Freeman K, Johnson S, Kandala NB, Grove A, Gurung B, Morrow S, Clarke A|date=September 2013|title=Aspirin for prophylactic use in the primary prevention of cardiovascular disease and cancer: a systematic review and overview of reviews|url=https://doi.org/10.3310%2Fhta17430|journal=]|volume=17|issue=43|pages=1–253|doi=10.3310/hta17430|pmc=4781046|pmid=24074752}}</ref> Nevertheless, many ]s continue to recommend aspirin for primary prevention,<ref>{{cite journal | vauthors = Matthys F, De Backer T, De Backer G, Stichele RV | title = Review of guidelines on primary prevention of cardiovascular disease with aspirin: how much evidence is needed to turn a tanker? | journal = European Journal of Preventive Cardiology | volume = 21 | issue = 3 | pages = 354–65 | date = March 2014 | pmid = 23610452 | doi = 10.1177/2047487312472077 | s2cid = 28350632 | doi-access = free }}</ref> and some researchers feel that those with very high cardiovascular risk but low risk of bleeding should continue to receive aspirin.<ref>{{cite journal | vauthors = Hodis HN, Mack WJ | title = Hormone replacement therapy and the association with coronary heart disease and overall mortality: clinical application of the timing hypothesis | journal = The Journal of Steroid Biochemistry and Molecular Biology | volume = 142 | pages = 68–75 | date = July 2014 | pmid = 23851166 | doi = 10.1016/j.jsbmb.2013.06.011 | s2cid = 30838065 }}</ref>
The 12 lead ECG is used to classify patients into one of three groups:<ref name="ECC_2005_ACS">{{cite journal | title=2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care - Part 8: Stabilization of the Patient With Acute Coronary Syndromes | journal=Circulation | year=2005 | volume=112 | pages=IV–89–IV–110 | doi=10.1161/CIRCULATIONAHA.105.166561 | url=http://circ.ahajournals.org/cgi/content/full/112/24_suppl/IV-89}}</ref>
# those with ST segment elevation or new bundle branch block (suspicious for acute injury and a possible candidate for acute reperfusion therapy with ] or primary ]),
# those with ST segment depression or T wave inversion (suspicious for ischemia), and
# those with a so-called non-diagnostic or normal ECG.


=== Secondary prevention ===
A normal ECG does not rule out acute myocardial infarction. Sometimes the earliest presentation of acute myocardial infarction is the hyperacute T wave, which is treated the same as ST segment elevation.<ref name=Hyperacute2002>{{cite journal |author=Somers MP, Brady WJ, Perron AD, Mattu A |title=The prominant T wave: electrocardiographic differential diagnosis |journal=Am J Emerg Med |volume=20 |issue=3 |pages=243–51 |year=2002 |month=May |pmid=11992348 |doi=10.1053/ajem.2002.32630}}</ref> In practice this is rarely seen, because it only exists for 2-30 minutes after the onset of infarction.<ref name="ACS_Clin_NA">{{cite journal |author=Smith SW, Whitwam W |title=Acute coronary syndromes |journal=Emerg. Med. Clin. North Am. |volume=24 |issue=1 |pages=53–89, vi |year=2006 |month=February |pmid=16308113 |doi=10.1016/j.emc.2005.08.008}}</ref> Hyperacute T waves need to be distinguished from the peaked T waves associated with ].<ref name="ECG_Noncardiac">{{cite journal |author=Van Mieghem C, Sabbe M, Knockaert D |title=The clinical value of the ECG in noncardiac conditions |journal=Chest |volume=125 |issue=4 |pages=1561–76 |year=2004 |month=April |pmid=15078775 |doi= |url=http://www.chestjournal.org/cgi/content/full/125/4/1561}}</ref> The current guidelines for the ECG diagnosis of acute myocardial infarction require at least 1 mm (0.1 mV) of ST segment elevation in the limb leads, and at least 2 mm elevation in the precordial leads. These elevations must be present in anatomically contiguous leads.<ref name="ECC_2005_ACS"/> (I, aVL, V5, V6 correspond to the lateral wall; V1-V4 correspond to the anterior wall; II, III, aVF correspond to the inferior wall.) This criterion is problematic, however, as acute myocardial infarction is not the most common cause of ST segment elevation in ] patients.<ref name="Cause_ST_ED">{{cite journal |author=Brady WJ, Perron AD, Martin ML, Beagle C, Aufderheide TP |title=Cause of ST segment abnormality in ED chest pain patients |journal=Am J Emerg Med |volume=19 |issue=1 |pages=25–8 |year=2001 |month=January |pmid=11146012 |doi=10.1053/ajem.2001.18029 |url=}}</ref> Over 90% of healthy men have at least 1 mm (0.1 mV) of ST segment elevation in at least one precordial lead.<ref name="ST_Other_MI">{{cite journal |author=Wang K, Asinger RW, Marriott HJ |title=ST-segment elevation in conditions other than acute myocardial infarction |journal=N. Engl. J. Med. |volume=349 |issue=22 |pages=2128–35 |year=2003 |month=November |pmid=14645641 |doi=10.1056/NEJMra022580 |url=}}</ref> The clinician must therefore be well versed in recognizing the so-called ECG mimics of acute myocardial infarction, which include ], ], ], ], ], ], and ].<ref name="ECG_Confound">{{cite journal |author=Brady WJ, Chan TC, Pollack M |title=Electrocardiographic manifestations: patterns that confound the EKG diagnosis of acute myocardial infarction-left bundle branch block, ventricular paced rhythm, and left ventricular hypertrophy |journal=J Emerg Med |volume=18 |issue=1 |pages=71–8 |year=2000 |month=January |pmid=10645842 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0736-4679(99)00178-X}}</ref><ref name="STE_AMI_non-AMI">{{cite journal |author=Brady WJ, Perron AD, Chan T |title=Electrocardiographic ST-segment elevation: correct identification of acute myocardial infarction (AMI) and non-AMI syndromes by emergency physicians |journal=Acad Emerg Med |volume=8 |issue=4 |pages=349–60 |year=2001 |month=April |pmid=11282670 |doi= |url=}}</ref><ref name="ST_Other_MI">{{cite journal |author=Wang K, Asinger RW, Marriott HJ |title=ST-segment elevation in conditions other than acute myocardial infarction |journal=N. Engl. J. Med. |volume=349 |issue=22 |pages=2128–35 |year=2003 |month=November |pmid=14645641 |doi=10.1056/NEJMra022580 |url=}}</ref>
There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as ] after an initial myocardial infarct.<ref name=Reed2017 /> Recommendations include ], a gradual return to exercise, eating a healthy ], low in ] and low in ], ], exercising, and trying to achieve a healthy weight.<ref name=Reed2017 /><ref name=NICE172 /> Exercise is both safe and effective even if people have had stents or heart failure,<ref>{{cite journal | vauthors = Anderson L, Taylor RS | title = Cardiac rehabilitation for people with heart disease: an overview of Cochrane systematic reviews | journal = The Cochrane Database of Systematic Reviews | volume = 2021 | issue = 12 | pages = CD011273 | date = December 2014 | pmid = 25503364 | doi = 10.1002/14651858.CD011273.pub2 | pmc = 7087435 | hdl-access = free | hdl = 10871/19152 }}</ref> and is recommended to start gradually after 1–2 weeks.<ref name=Reed2017 /> Counselling should be provided relating to medications used, and for warning signs of depression.<ref name=Reed2017 /> Previous studies suggested a benefit from ] supplementation but this has not been confirmed.<ref name=NICE172 />


==== Medications ====
] and ] interferes with the electrocardiographic diagnosis of acute myocadial infarction. The GUSTO investigators Sgarbossa et al. developed a set of criteria for identifying acute myocardial infarction in the presence of left bundle branch block and paced rhythm. They include concordant ST segment elevation > 1 mm (0.1 mV), discordant ST segment elevation > 5 mm (0.5 mV), and concordant ST segment depression in the left precordial leads.<ref name="NEJM_Sgarbossa">{{cite journal |author=Sgarbossa EB, Pinski SL, Barbagelata A, ''et al'' |title=Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators |journal=N. Engl. J. Med. |volume=334 |issue=8 |pages=481–7 |year=1996 |month=February |pmid=8559200 |doi= |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=8559200&promo=ONFLNS19}}</ref> The presence of reciprocal changes on the 12 lead ECG may help distinguish true acute myocardial infarction from the mimics of acute myocardial infarction. The contour of the ST segment may also be helpful, with a straight or upwardly convex (non-concave) ST segment favoring the diagnosis of acute myocardial infarction.<ref name="Contour_ST">{{cite journal |author=Brady WJ, Syverud SA, Beagle C, ''et al'' |title=Electrocardiographic ST-segment elevation: the diagnosis of acute myocardial infarction by morphologic analysis of the ST segment |journal=Acad Emerg Med |volume=8 |issue=10 |pages=961–7 |year=2001 |month=October |pmid=11581081 |doi= |url=}}</ref>
Following a heart attack, nitrates, when taken for two days, and ] decrease the risk of death.<ref>{{cite journal | vauthors = Perez MI, Musini VM, Wright JM | title = Effect of early treatment with anti-hypertensive drugs on short and long-term mortality in patients with an acute cardiovascular event | journal = The Cochrane Database of Systematic Reviews | issue = 4 | pages = CD006743 | date = October 2009 | pmid = 19821384 | doi = 10.1002/14651858.CD006743.pub2 }}</ref> Other medications include:


] is continued indefinitely, as well as another antiplatelet agent such as clopidogrel or ticagrelor ("dual antiplatelet therapy" or DAPT) for up to twelve months.<ref name=NICE172 /> If someone has another medical condition that requires anticoagulation (e.g. with ]) this may need to be adjusted based on risk of further cardiac events as well as bleeding risk.<ref name=NICE172 /> In those who have had a stent, more than 12 months of clopidogrel plus aspirin does not affect the risk of death.<ref>{{cite journal | vauthors = Elmariah S, Mauri L, Doros G, Galper BZ, O'Neill KE, Steg PG, Kereiakes DJ, Yeh RW | display-authors = 6 | title = Extended duration dual antiplatelet therapy and mortality: a systematic review and meta-analysis | journal = Lancet | volume = 385 | issue = 9970 | pages = 792–8 | date = February 2015 | pmid = 25467565 | pmc = 4386690 | doi = 10.1016/S0140-6736(14)62052-3 }}</ref>
The constellation of leads with ST segment elevation enables the clinician to identify what area of the heart is injured, which in turn helps predict the culprit artery.


] therapy such as ] or ] is recommended to be started within 24 hours, provided there is no acute heart failure or ].<ref name=AHA2013 /><ref name=AHANSTEMI2014 /> The dose should be increased to the highest tolerated.<ref name=NICE172 /> Contrary to most guidelines, the use of beta blockers does not appear to affect the risk of death,<ref>{{cite journal | vauthors = Bangalore S, Makani H, Radford M, Thakur K, Toklu B, Katz SD, DiNicolantonio JJ, Devereaux PJ, Alexander KP, Wetterslev J, Messerli FH | display-authors = 6 | title = Clinical outcomes with β-blockers for myocardial infarction: a meta-analysis of randomized trials | journal = The American Journal of Medicine | volume = 127 | issue = 10 | pages = 939–953 | date = October 2014 | pmid = 24927909 | doi = 10.1016/j.amjmed.2014.05.032 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Safi S, Sethi NJ, Nielsen EE, Feinberg J, Jakobsen JC, Gluud C | title = Beta-blockers for suspected or diagnosed acute myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 12 | issue = 12 | pages = CD012484 | date = December 2019 | pmid = 31845756 | pmc = 6915833 | doi = 10.1002/14651858.CD012484.pub2 | collaboration = Cochrane Heart Group }}</ref> possibly because other treatments for MI have improved. When beta blocker medication is given within the first 24–72 hours of a STEMI no lives are saved.<!-- <ref name=BetaNNT2015 /> --> However, 1 in 200 people were prevented from a repeat heart attack, and another 1 in 200 from having an abnormal heart rhythm.<!-- <ref name=BetaNNT2015 /> --> Additionally, for 1 in 91 the medication causes a ].<ref name=BetaNNT2015>{{cite web|title=Beta Blockers for Acute Heart Attack (Myocardial Infarction)| vauthors = Newman D |date=19 August 2010|url=http://www.thennt.com/nnt/beta-blockers-for-heart-attack/|website=TheNNT.com|access-date=11 December 2015|url-status=live|archive-url=https://web.archive.org/web/20151222092449/http://www.thennt.com/nnt/beta-blockers-for-heart-attack/|archive-date=22 December 2015}}</ref>
{| class=wikitable border="1" cellspacing="0" cellpadding="5" align="center"
! Wall Affected
! Leads Showing ST Segment Elevation
! Leads Showing Reciprocal ST Segment Depression
! Suspected Culprit Artery
|-
| Septal
| V<sub>1</sub>, V<sub>2</sub>
| None
| ]
|-
| Anterior
| V<sub>3</sub>, V<sub>4</sub>
| None
| ]
|-
| Anteroseptal
| V<sub>1</sub>, V<sub>2</sub>, V<sub>3</sub>, V<sub>4</sub>
| None
| ]
|-
| Anterolateral
| V<sub>3</sub>, V<sub>4</sub>, V<sub>5</sub>, V<sub>6</sub>, I, aVL
| II, III, aVF
| ], ], or ]
|-
| Extensive anterior (Sometimes called Anteroseptal with Lateral extension)
| V<sub>1</sub>,V<sub>2</sub>,V<sub>3</sub>, V<sub>4</sub>, V<sub>5</sub>, V<sub>6</sub>, I, aVL
| II, III, aVF
| ]
|-
| ]
| II, III, aVF
| I, aVL
| ]
|-
| Lateral
| I, aVL</sub>, V<sub>5</sub>, V<sub>6</sub>
| II, III, aVF
| ] or ]
|-
| Posterior (Usually associated with Inferior or Lateral but can be isolated)
| V<sub>7</sub>, V<sub>8</sub>, V<sub>9</sub>
| V<sub>1</sub>,V<sub>2</sub>,V<sub>3</sub>, V<sub>4</sub>
| ] (branch of the ] or ])
|-
| ] (Usually associated with Inferior)
| II, III, aVF, V<sub>1</sub>, V<sub>4</sub>R
| I, aVL
| ]
|-
|}


] therapy should be started within 24 hours and continued indefinitely at the highest tolerated dose. This is provided there is no evidence of worsening ], ], low blood pressure, or known narrowing of the ].<ref name=Reed2017 /> Those who cannot tolerate ACE inhibitors may be treated with an ].<ref name=NICE172 />
As the myocardial infarction evolves, there may be loss of R wave height and development of pathological Q waves (defined as Q waves deeper than 1 mm and wider than 1 mm.) T wave inversion may persist for months or even permanently following acute myocardial infarction.<ref>{{cite journal | author = Morris F, Brady W | title = ABC of clinical electrocardiography: Acute myocardial infarction-Part I | journal = BMJ | volume = 324 | issue = 7341 | pages = 831–4 | year = 2002 | pmid = 1934778 | doi = 10.1136/bmj.324.7341.831}} {{PMC|1122768}}</ref> Typically, however, the T wave recovers, leaving a pathological Q wave as the only remaining evidence that an acute myocardial infarction has occurred.


] therapy has been shown to reduce mortality and subsequent cardiac events and should be commenced to lower LDL cholesterol. Other medications, such as ], may also be added with this goal in mind.<ref name=Reed2017 />
===Cardiac markers===
{{main|Cardiac marker}}


]s (] or ]) may be used if there is evidence of left ventricular dysfunction after an MI, ideally after beginning treatment with an ACE inhibitor.<ref name=NICE172 /><ref name="pmid26891235">{{cite journal | vauthors = Le HH, El-Khatib C, Mombled M, Guitarian F, Al-Gobari M, Fall M, Janiaud P, Marchant I, Cucherat M, Bejan-Angoulvant T, Gueyffier F | display-authors = 6 | title = Impact of Aldosterone Antagonists on Sudden Cardiac Death Prevention in Heart Failure and Post-Myocardial Infarction Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials | journal = PLOS ONE | volume = 11 | issue = 2 | pages = e0145958 | date = 2016 | pmid = 26891235 | pmc = 4758660 | doi = 10.1371/journal.pone.0145958 | bibcode = 2016PLoSO..1145958L | doi-access = free }}</ref>
Cardiac markers or cardiac enzymes are proteins from cardiac tissue found in the blood. These proteins are released into the bloodstream when damage to the heart occurs, as in the case of a myocardial infarction. Until the 1980s, the enzymes ] and ] were used to assess cardiac injury. Then it was found that disproportional elevation of the ''MB'' subtype of the enzyme ] (CK) was very specific for myocardial injury. Current guidelines are generally in favor of ] sub-units I or T, which are very specific for the heart muscle and are thought to rise before permanent injury develops.<ref>{{cite journal | author = Eisenman A | title = Troponin assays for the diagnosis of myocardial infarction and acute coronary syndrome: where do we stand? | journal = Expert Rev Cardiovasc Ther | volume = 4 | issue = 4 | pages = 509–14 | year = 2006 | pmid = 16918269 | doi = 10.1586/14779072.4.4.509}}</ref> Elevated troponins in the setting of chest pain may accurately predict a high likelihood of a myocardial infarction in the near future.<ref>{{cite journal | author = Aviles RJ, Askari AT, Lindahl B, Wallentin L, Jia G, Ohman EM, Mahaffey KW, Newby LK, Califf RM, Simoons ML, Topol EJ, Berger P, Lauer MS | title = ] T levels in patients with acute coronary syndromes, with or without renal dysfunction | journal = N Engl J Med | volume = 346 | issue = 26 | pages = 2047–52 | year = 2002 | pmid = 12087140 | doi = 10.1056/NEJMoa013456}}. </ref> New markers such as ] are under investigation.<ref name="pmid15774573">{{cite journal |author=Apple FS, Wu AH, Mair J, ''et al'' |title=Future biomarkers for detection of ischemia and risk stratification in acute coronary syndrome |journal=Clin. Chem. |volume=51 |issue=5 |pages=810–24 |year=2005 |pmid=15774573 |doi=10.1373/clinchem.2004.046292|url=http://www.clinchem.org/cgi/content/full/51/5/810}}</ref>


==== Other ====
The diagnosis of myocardial infarction requires two out of three components (history, ECG, and enzymes). When damage to the heart occurs, levels of cardiac markers rise over time, which is why ]s for them are taken over a 24-hour period. Because these enzyme levels are not elevated immediately following a heart attack, patients presenting with chest pain are generally treated with the assumption that a myocardial infarction has occurred and then evaluated for a more precise diagnosis.<ref name="Braunwald-2002">{{cite journal | author=Braunwald E, Antman EM, Beasley JW, Califf RM, Cheitlin MD, Hochman JS, Jones RH, Kereiakes D, Kupersmith J, Levin TN, Pepine CJ, Schaeffer JW, Smith EE III, Steward DE, Théroux P. | title=ACC/AHA 2002 guideline update for the management of patients with unstable angina and non–ST-segment elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina) | journal=J Am Coll Cardiol | year=2002 | volume=40 | pages=1366–74 | pmid=12383588 | format=] | url=http://www.acc.org/qualityandscience/clinical/guidelines/unstable/incorporated/UA_incorporated.pdf}}</ref>
A ], an electric device connected to the heart and surgically inserted under the skin, may be recommended. This is particularly if there are any ongoing signs of heart failure, with a low ] and a New York Heart Association grade II or III after 40 days of the infarction.<ref name=Reed2017 /> Defibrillators detect potentially fatal arrhythmia and deliver an electrical shock to the person to depolarize a critical mass of the heart muscle.<ref name="Hazinski2015">{{cite journal | vauthors = Hazinski MF, Nolan JP, Aickin R, Bhanji F, Billi JE, Callaway CW, Castren M, de Caen AR, Ferrer JM, Finn JC, Gent LM, Griffin RE, Iverson S, Lang E, Lim SH, Maconochie IK, Montgomery WH, Morley PT, Nadkarni VM, Neumar RW, Nikolaou NI, Perkins GD, Perlman JM, Singletary EM, Soar J, Travers AH, Welsford M, Wyllie J, Zideman DA | display-authors = 6 | title = Part 1: Executive Summary: 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations | journal = Circulation | volume = 132 | issue = 16 Suppl 1 | pages = S2–39 | date = October 2015 | pmid = 26472854 | doi = 10.1161/CIR.0000000000000270 | type = Review | doi-access = free }}</ref>

===Angiography===
] of the coronary arteries.]]
{{main|Coronary catheterization}}

In difficult cases or in situations where intervention to restore blood flow is appropriate, coronary ] can be performed. A ] is inserted into an artery (usually the ]) and pushed to the vessels supplying the heart. A radio-opaque dye is administered through the catheter and a sequence of x-rays (fluoroscopy) is performed. Obstructed or narrowed arteries can be identified, and ] applied as a therapeutic measure (see below). Angioplasty requires extensive skill, especially in emergency settings. It is performed by a physician trained in ].

===Histopathology===
{{See|Timeline of myocardial infarction pathology}}
]) from autopsy specimen of myocardial infarct (7 days post-infarction).]]
]
] examination of the heart may reveal infarction at autopsy. Under the microscope, myocardial infarction presents as a circumscribed area of ischemic, coagulative ] (cell death). On gross examination, the infarct is not identifiable within the first 12 hours.<ref name=rubin546>{{cite book | coauthors = Emanuel Rubin, Fred Gorstein, Raphael Rubin, Roland Schwarting, David Strayer | title = Rubin's Pathology - Clinicopathological Foundations of Medicine | publisher = Lippincott Williams & Wilkins | date = 2001 | location = Maryland | pages = 546 | isbn = 0-7817-4733-3 }}</ref>

Although earlier changes can be discerned using ], one of the earliest changes under a normal microscope are so-called ''wavy fibers''.<ref name=Eichbaum1975>Eichbaum FW. "'Wavy' myocardial fibers in spontaneous and experimental adrenergic cardiopathies" ''Cardiology'' 1975; '''60'''(6): 358–65. PMID 782705</ref> Subsequently, the myocyte ] becomes more ] (pink) and the cells lose their transversal striations, with typical changes and eventually loss of the ].<ref name=histopathologyIndia>S Roy. . Retrieved November 28, 2006.</ref> The interstitium at the margin of the infarcted area is initially infiltrated with ]s, then with ]s and ]s, who ] ("eat") the myocyte debris. The necrotic area is surrounded and progressively invaded by ], which will replace the infarct with a fibrous (]ous) ] (which are typical steps in ]). The interstitial space (the space between cells outside of blood vessels) may be infiltrated with ]s.<ref name=rubin546/>

These features can be recognized in cases where the perfusion was not restored; reperfused infarcts can have other hallmarks, such as contraction band necrosis.<ref name="Fishbein-1990">{{cite journal | author=Fishbein MC. | title=Reperfusion injury | journal=Clin Cardiol | year=1990 | volume=13 | issue=3 | pages=213–7 | pmid=2182247 | doi=10.1152/ajpheart.00270.2002 | doi_brokendate=2008-06-25}}</ref>


== First aid == == First aid ==
{{Further|Management of acute coronary syndrome#Patient-dependent initial measures}}
As myocardial infarction is a common medical emergency, the signs are often part of ] courses. The ] also apply in the case of myocardial infarction.


Taking aspirin helps to reduce the risk of ] in people with myocardial infarction.<ref name="reed">{{Cite journal |last1=Reed |first1=Grant W |last2=Rossi |first2=Jeffrey E |last3=Cannon |first3=Christopher P |date=January 2017 |title=Acute myocardial infarction |url=https://dx.doi.org/10.1016/S0140-6736(16)30677-8 |journal=The Lancet |volume=389 |issue=10065 |pages=197–210 |doi=10.1016/s0140-6736(16)30677-8 |pmid=27502078 |issn=0140-6736}}</ref>
===Immediate care===
When symptoms of myocardial infarction occur, people wait an average of three hours, instead of doing what is recommended: ] immediately.<ref name=FirstAid>. ]. Retrieved December 3, 2006.</ref><ref name="ActInTime"> - ]. Retrieved December 13, 2006.</ref> Acting immediately by calling the emergency services can prevent sustained damage to the heart ("time is muscle").<ref name=TimeIsMuscle>. Early Heart Attack Care, St. Agnes Healthcare. Retrieved November 29, 2006.</ref>


== Management ==
Certain positions allow the patient to rest in a position which minimizes breathing difficulties. A half-sitting position with knees bent is often recommended. Access to more oxygen can be given by opening the window and widening the collar for easier breathing.
{{Main|Management of acute coronary syndrome}}
A myocardial infarction requires immediate medical attention. Treatment aims to preserve as much heart muscle as possible, and to prevent further complications.<ref name=Harrisons2015 /> Treatment depends on whether the myocardial infarction is a STEMI or NSTEMI.<ref name=Reed2017 /> Treatment in general aims to unblock blood vessels, reduce blood clot enlargement, reduce ischemia, and modify risk factors with the aim of preventing future MIs.<ref name=Harrisons2015 /> In addition, the main treatment for myocardial infarctions with ECG evidence of ST elevation (STEMI) include ] or ], although PCI is also ideally conducted within 1–3 days for NSTEMI.<ref name=Reed2017 /> In addition to ], risk stratification may be used to guide treatment, such as with the ] and ] scoring systems.<ref name="Davidsons2010" /><ref name=Reed2017 /><ref>{{cite journal | vauthors = Hess EP, Agarwal D, Chandra S, Murad MH, Erwin PJ, Hollander JE, Montori VM, Stiell IG | display-authors = 6 | title = Diagnostic accuracy of the TIMI risk score in patients with chest pain in the emergency department: a meta-analysis | journal = CMAJ | volume = 182 | issue = 10 | pages = 1039–44 | date = July 2010 | pmid = 20530163 | pmc = 2900327 | doi = 10.1503/cmaj.092119 }}</ref>


=== Pain ===
] can be given quickly (if the patient is not ] to aspirin); but taking aspirin before calling the ] may be associated with unwanted delay.<ref name="Brown-2000">{{cite journal | author=Brown AL, Mann NC, Daya M, Goldberg R, Meischke H, Taylor J, Smith K, Osganian S, Cooper L. | title=Demographic, belief, and situational factors influencing the decision to utilize emergency medical services among chest pain patients. Rapid Early Action for Coronary Treatment (REACT) study | journal=Circulation | year=2000 | volume=102 | issue=2 | pages=173–8 | pmid=10889127}}</ref> Aspirin has an ] effect which inhibits formation of further ] (blood clots) that clog arteries. Chewing is the preferred method of administration, so that the Aspirin can be ] quickly. Dissolved soluble preparations or ] administration can also be used. U.S. guidelines recommend a dose of 162–325 mg.<ref name=Antman-2004>{{cite journal | author = Antman EM, Anbe DT, Armstrong PW, Bates ER, Green LA, Hand M, Hochman JS, Krumholz HM, Kushner FG, Lamas GA, Mullany CJ, Ornato JP, Pearle DL, Sloan MA, Smith SC Jr | year = 2004 | title = ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1999 Guidelines for the Management of Patients With Acute Myocardial Infarction) | journal=J Am Coll Cardiol | volume=44 | pages=671–719 | pmid=15358045 | url=http://www.acc.org/qualityandscience/clinical/guidelines/stemi/Guideline1/index.htm}}</ref> Australian guidelines recommend a dose of 150–300 mg.<ref name=Rossi>Rossi S, editor. ] 2006. Adelaide: Australian Medicines Handbook; 2006. ISBN 0-9757919-2-3.</ref>
The pain associated with myocardial infarction is often treated with ], a ], or ] medications such as ].<ref name=Harrisons2015 /> Nitroglycerin (given ] or ]) may improve blood supply to the heart.<ref name=Harrisons2015 /> It is an important part of therapy for its pain relief effects, though there is no proven benefit to ].<ref name=Harrisons2015 /><ref>{{cite web| vauthors = Reeder G |title=Nitrates in the management of acute coronary syndrome|url=https://www.uptodate.com/contents/nitrates-in-the-management-of-acute-coronary-syndrome|website=www.uptodate.com|access-date=24 May 2017 |date=27 December 2016|url-status=live |archive-url= https://web.archive.org/web/20170728135423/https://www.uptodate.com/contents/nitrates-in-the-management-of-acute-coronary-syndrome |archive-date=28 July 2017}}</ref> Morphine or other opioid medications may also be used, and are effective for the pain associated with STEMI.<ref name=Harrisons2015 /> There is poor evidence that morphine shows any benefit to ], and there is some evidence of potential harm.<ref>{{cite journal | vauthors = Yadlapati A, Gajjar M, Schimmel DR, Ricciardi MJ, Flaherty JD | title = Contemporary management of ST-segment elevation myocardial infarction | journal = Internal and Emergency Medicine | volume = 11 | issue = 8 | pages = 1107–1113 | date = December 2016 | pmid = 27714584 | doi = 10.1007/s11739-016-1550-3 | s2cid = 23759756 }}</ref><ref>{{cite journal | vauthors = McCarthy CP, Mullins KV, Sidhu SS, Schulman SP, McEvoy JW | title = The on- and off-target effects of morphine in acute coronary syndrome: A narrative review | journal = American Heart Journal | volume = 176 | pages = 114–21 | date = June 2016 | pmid = 27264228 | doi = 10.1016/j.ahj.2016.04.004 }}</ref>


=== Antithrombotics ===
] (nitroglycerin) ]ly (under the tongue) can be given if available.
], an ], is given as a ] to reduce the clot size and reduce further clotting in the affected artery.<ref name=Harrisons2015 /><ref name=Reed2017 /> It is known to decrease mortality associated with acute myocardial infarction by at least 50%.<ref name=Reed2017 /> ] such as ], ] and ] are given concurrently, also as a ], with the dose depending on whether further surgical management or fibrinolysis is planned.<ref name=Reed2017 /> Prasugrel and ticagrelor are recommended in European and American guidelines, as they are active more quickly and consistently than clopidogrel.<ref name=Reed2017 /> P2Y12 inhibitors are recommended in both NSTEMI and STEMI, including in PCI, with evidence also to suggest improved mortality.<ref name=Reed2017 /> ]s, particularly in the unfractionated form, act at several points in the ], help to prevent the enlargement of a clot, and are also given in myocardial infarction, owing to evidence suggesting improved mortality rates.<ref name=Reed2017 /> In very high-risk scenarios, ] such as ] or ] may be used.<ref name=Reed2017 />


There is varying evidence on the mortality benefits in NSTEMI. A 2014 review of P2Y12 inhibitors such as ] found they do not change the risk of death when given to people with a suspected NSTEMI prior to PCI,<ref name=BMJP2Y12>{{cite journal | vauthors = Bellemain-Appaix A, Kerneis M, O'Connor SA, Silvain J, Cucherat M, Beygui F, Barthélémy O, Collet JP, Jacq L, Bernasconi F, Montalescot G | display-authors = 6 | title = Reappraisal of thienopyridine pretreatment in patients with non-ST elevation acute coronary syndrome: a systematic review and meta-analysis | journal = BMJ | volume = 349 | pages = g6269 | date = October 2014 | pmid = 25954988 | pmc = 4208629 | doi = 10.1136/bmj.g6269 }}</ref> nor do heparins change the risk of death.<ref name=And2014 /> They do decrease the risk of having a further myocardial infarction.<ref name=Reed2017 /><ref name=And2014>{{cite journal | vauthors = Andrade-Castellanos CA, Colunga-Lozano LE, Delgado-Figueroa N, Magee K | title = Heparin versus placebo for non-ST elevation acute coronary syndromes | journal = The Cochrane Database of Systematic Reviews | volume = 6 | issue = 6 | pages = CD003462 | date = June 2014 | pmid = 24972265 | pmc = 6769062 | doi = 10.1002/14651858.CD003462.pub3 }}</ref>
If an ] (AED) is available the rescuer should immediately bring the AED to the patient's side and be prepared to follow its instructions, especially should the victim lose consciousness.


=== Angiogram ===
If possible the rescuer should obtain basic information from the victim, in case the patient is unable to answer questions once ]s arrive. The victim's name and any information regarding the nature of the victim's pain will be useful to health care providers. The exact time that these symptoms started may be critical for determining what interventions can be safely attempted once the victim reaches the medical center. Other useful pieces of information include what the patient was doing at the onset of symptoms, and anything else that might give clues to the pathology of the chest pain. It is also very important to relay any actions that have been taken, such as the number or dose of aspirin or nitroglycerin given, to the EMS personnel.
]
Primary ] (PCI) is the treatment of choice for STEMI if it can be performed in a timely manner, ideally within 90–120 minutes of contact with a medical provider.<ref name=Reed2017 /><ref name=Bagai2014>{{cite journal | vauthors = Bagai A, Dangas GD, Stone GW, Granger CB | title = Reperfusion strategies in acute coronary syndromes | journal = Circulation Research | volume = 114 | issue = 12 | pages = 1918–28 | date = June 2014 | pmid = 24902975 | doi = 10.1161/CIRCRESAHA.114.302744 | doi-access = free }}</ref> Some recommend it is also done in NSTEMI within 1–3 days, particularly when considered high-risk.<ref name=Reed2017 /> A 2017 review, however, did not find a difference between early versus later PCI in NSTEMI.<ref>{{cite journal | vauthors = Jobs A, Mehta SR, Montalescot G, Vicaut E, Van't Hof AW, Badings EA, Neumann FJ, Kastrati A, Sciahbasi A, Reuter PG, Lapostolle F, Milosevic A, Stankovic G, Milasinovic D, Vonthein R, Desch S, Thiele H | display-authors = 6 | title = Optimal timing of an invasive strategy in patients with non-ST-elevation acute coronary syndrome: a meta-analysis of randomised trials | journal = Lancet | volume = 390 | issue = 10096 | pages = 737–746 | date = August 2017 | pmid = 28778541 | doi = 10.1016/S0140-6736(17)31490-3 | s2cid = 4489347 }}</ref>


PCI involves small probes, inserted through peripheral blood vessels such as the ] or ] into the blood vessels of the heart. The probes are then used to identify and clear blockages ], which are dragged through the blocked segment, ], or ].<ref name=Harrisons2015 /><ref name=Reed2017 /> ] is only considered when the affected area of heart muscle is large, and PCI is unsuitable, for example with difficult cardiac anatomy.<ref>{{cite journal | vauthors = Wijns W, Kolh P, Danchin N, Di Mario C, Falk V, Folliguet T, Garg S, Huber K, James S, Knuuti J, Lopez-Sendon J, Marco J, Menicanti L, Ostojic M, Piepoli MF, Pirlet C, Pomar JL, Reifart N, Ribichini FL, Schalij MJ, Sergeant P, Serruys PW, Silber S, Sousa Uva M, Taggart D | display-authors = 6 | title = Guidelines on myocardial revascularization | journal = European Heart Journal | volume = 31 | issue = 20 | pages = 2501–55 | date = October 2010 | pmid = 20802248 | doi = 10.1093/eurheartj/ehq277 | doi-access = free }}</ref> After PCI, people are generally placed on ] indefinitely and on dual antiplatelet therapy (generally aspirin and ]) for at least a year.<ref name=AHA2013 /><ref name=Reed2017 /><ref>{{cite journal | vauthors = Dalal F, Dalal HM, Voukalis C, Gandhi MM | title = Management of patients after primary percutaneous coronary intervention for myocardial infarction | journal = BMJ | volume = 358 | pages = j3237 | date = July 2017 | pmid = 28729460 | doi = 10.1136/bmj.j3237 | s2cid = 46847680 }}</ref>
Other general first aid principles include monitoring pulse, breathing, ] and, if possible, the blood pressure of the patient. In case of ], ] (CPR) can be administered.


=== Fibrinolysis ===
===Automatic external defibrillation (AED)===
Since the publication of data showing that the availability of ]s (AEDs) in public places may significantly increase chances of survival, many of these have been installed in public buildings, ] facilities, and in non-ambulance emergency vehicles (e.g. ]s and ]s). AEDs analyze the heart's rhythm and determine whether the rhythm is amenable to ] ("shockable"), as in ] and ].

===Emergency services===
] (EMS) Systems vary considerably in their ability to evaluate and treat patients with suspected acute myocardial infarction. Some provide as little as first aid and early defibrillation. Others employ highly trained paramedics with sophisticated technology and advanced protocols.<ref name="ACC_AHA_STEMI">{{cite journal |author=Antman EM, Anbe DT, Armstrong PW, ''et al'' |title=ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction--executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1999 guidelines for the management of patients with acute myocardial infarction) |journal=J. Am. Coll. Cardiol. |volume=44 |issue=3 |pages=671–719 |year=2004 |month=August |pmid=15358045 |doi=10.1016/j.jacc.2004.07.002 |url=}}</ref> Early access to ] is promoted by a 9-1-1 system currently available to 90% of the population in the United States.<ref name="ACC_AHA_STEMI"/> Most are capable of providing ], IV access, sublingual ], ], and ]. Some are capable of providing ] in the prehospital setting.<ref name="ER_TIMI_19">{{cite journal |author=Morrow DA, Antman EM, Sayah A, ''et al'' |title=Evaluation of the time saved by prehospital initiation of reteplase for ST-elevation myocardial infarction: results of The Early Retavase-Thrombolysis in Myocardial Infarction (ER-TIMI) 19 trial |journal=J. Am. Coll. Cardiol. |volume=40 |issue=1 |pages=71–7 |year=2002 |month=July |pmid=12103258 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0735109702019368}}</ref><ref name="Morrison-2000">{{cite journal | author=Morrison LJ, Verbeek PR, McDonald AC, Sawadsky BV, Cook DJ. | title=Mortality and prehospital thrombolysis for acute myocardial infarction: A meta-analysis | journal=JAMA | year=2000 | volume=283 | issue=20 | pages=2686–92 | format=] | url=http://jama.ama-assn.org/cgi/reprint/283/20/2686.pdf?ijkey=c72b289825a3fd6ace7545ef61cd70936485e7e1 | pmid=10819952 | doi = 10.1001/jama.283.20.2686}}</ref>

With ] emerging as the preferred therapy for ST segment elevation myocardial infarction, ] can play a key role in reducing ] intervals (the time from presentation to a hospital ] to the restoration of coronary artery blood flow) by performing a 12 lead ] in the field and using this information to triage the patient to the most appropriate medical facility.<ref>{{cite journal |author=Rokos IC, Larson DM, Henry TD, ''et al'' |title=Rationale for establishing regional ST-elevation myocardial infarction receiving center (SRC) networks |journal=Am. Heart J. |volume=152 |issue=4 |pages=661–7 |year=2006 |pmid=16996830 |doi=10.1016/j.ahj.2006.06.001}}</ref><ref name="EMS_PCI_Boston">{{cite journal |author=Moyer P, Feldman J, Levine J, ''et al'' |title=Implications of the Mechanical (PCI) vs Thrombolytic Controversy for ST Segment Elevation Myocardial Infarction on the Organization of Emergency Medical Services: The Boston EMS Experience |journal=Crit Pathw Cardiol |volume=3 |issue=2 |pages=53–61 |year=2004 |month=June |pmid=18340140 |doi=10.1097/01.hpc.0000128714.35330.6d |url=}}</ref><ref name="EMS_PCI">{{cite journal |author=Terkelsen CJ, Lassen JF, Nørgaard BL, ''et al'' |title=Reduction of treatment delay in patients with ST-elevation myocardial infarction: impact of pre-hospital diagnosis and direct referral to primary percutanous coronary intervention |journal=Eur. Heart J. |volume=26 |issue=8 |pages=770–7 |year=2005 |month=April |pmid=15684279 |doi=10.1093/eurheartj/ehi100 |url=}}T</ref><ref name="PCI_STEMI_National_Policy">{{cite journal |author=Henry TD, Atkins JM, Cunningham MS, ''et al'' |title=ST-segment elevation myocardial infarction: recommendations on triage of patients to heart attack centers: is it time for a national policy for the treatment of ST-segment elevation myocardial infarction? |journal=J. Am. Coll. Cardiol. |volume=47 |issue=7 |pages=1339–45 |year=2006 |month=April |pmid=16580518 |doi=10.1016/j.jacc.2005.05.101 |url=}}</ref> In addition, the 12 lead ECG can be transmitted to the receiving hospital, which enables time saving decisions to be made prior to the patient's arrival. This may include a "cardiac alert" or "STEMI alert" that calls in off duty personnel in areas where the ] is not staffed 24 hours a day.<ref>Rokos I. and Bouthillet T., ''STEMI Systems'', Issue Two, May 2007. Accessed June 16, 2007.</ref> Even in the absence of a formal alerting program, prehospital 12 lead ECGs are independently associated with reduced door to treatment intervals in the emergency department.<ref name=Cannon_176>{{cite book |author=Cannon, Christopher |title=Management of acute coronary syndromes |publisher=Humana Press |location=Totowa, NJ |year=1999 |pages= |isbn=0-89603-552-2 |oclc= |doi= |accessdate=}}</ref>

===Wilderness first aid===
In ], a possible heart attack justifies ] by the fastest available means, including ], even in the earliest or precursor stages. The patient will rapidly be incapable of further exertion and have to be carried out.

===Air travel===
Certified personnel traveling by commercial aircraft may be able to assist an MI patient by using the on-board ], which may contain some cardiac drugs (such as ] spray, ], or ] painkillers), an AED,<ref>{{cite web|last=Youngwith|first=Janice|title=Saving hearts in the air|url=http://www.dailyherald.com/special/americanheartmonth/2008/index.asp?id=11|publisher=Dailyherald.com|date=2008-02-06|accessdate=2008-06-12}}</ref> and ]. Pilots may divert the flight to land at a nearby airport. ] are being introduced by some airlines, and they can be used by both on-board and ground-based physicians.<ref name=aircraft>Dowdall N. "'Is there a doctor on the aircraft?' Top 10 in-flight medical emergencies." ''BMJ'' 2000; '''321'''(7272):1336-7. PMID 11090520. {{PMC|1119071}}</ref>

== Treatment ==
A heart attack is a ] which demands both immediate attention and activation of the ]. The ultimate goal of the management in the acute phase of the disease is to salvage as much myocardium as possible and prevent further complications. As time passes, the risk of damage to the heart muscle increases; hence the phrase that in myocardial infarction, "time is muscle," and time wasted is muscle lost.<ref name="TimeIsMuscle"/>

The treatments itself may have complications. If attempts to restore the blood flow are initiated after a critical period of only a few hours, the result is ] instead of amelioration.<ref name=Faxon2005>Faxon DP. "Coronary interventions and their impact on post myocardial infarction survival." ''Clin Cardiol'' 2005; '''28'''(11 Suppl 1):I38-44. PMID 16450811</ref> Other treatment modalities may also cause complications; the use of antithrombotics for example carries an increased risk of ].

===First line===
], ], ] (nitroglycerin) and ] (usually ], although experts often argue this point), hence the popular ] ''MONA'', ''morphine, oxygen, nitro, aspirin'') are administered as soon as possible. In many areas, first responders can be trained to administer these prior to arrival at the hospital. Morphine is classically the preferred pain relief drug due to its ability to dilate blood vessels, which aids in blood flow to the heart as well as its pain relief properties. However, morphine can also cause hypotension (usually in the setting of hypovolemia), and should be avoided in the case of right ventricular infarction. Moreover, the CRUSADE trial also demonstrated an increase in mortality with administering morphine in the setting of NSTEMI.<ref name="pmid15976786">{{cite journal |author=Meine TJ, Roe MT, Chen AY, ''et al'' |title=Association of intravenous morphine use and outcomes in acute coronary syndromes: results from the CRUSADE Quality Improvement Initiative |journal=Am Heart J |volume=149 |issue=6 |pages=1043–9 |year=2005 |pmid=15976786 |doi=10.1016/j.ahj.2005.02.010 |url=http://linkinghub.elsevier.com/retrieve/pii/S0002870305001493}}</ref>

Of the first line agents, only aspirin has been proven to decrease ].<ref name="Lancet1988-ISIS2">{{cite journal | author=ISIS-2 Collaborative group | title=Randomized trial of intravenous streptokinase, oral aspirin, both, or neither among 17,187 cases of suspected acute myocardial infarction: ISIS-2 | journal=Lancet |volume=2 |issue=8607 |pages=349–60 | year=1988 | pmid=2899772}}</ref>

Once the diagnosis of myocardial infarction is confirmed, other pharmacologic agents are often given. These include ]s,<ref name="ISIS-1">{{cite journal | author=ISIS-1 Collaborative Group | title=Randomised trial of intravenous atenolol among 16 027 cases of suspected acute myocardial infarction: ISIS-1 | journal=Lancet | year=1986 | volume=2 | issue=8498 | pages=57–66 | pmid=2873379}}</ref><ref name="TIMI-2">{{cite journal | author=The TIMI Study Group | title=Comparison of invasive and conservative strategies after treatment with intravenous tissue plasminogen activator in acute myocardial infarction | journal=N Engl J Med | year=1989 | volume=320 | issue=10 | pages=618–27 | pmid=2563896}}</ref> anticoagulation (typically with ]),<ref name="Antman-2004"/> and possibly additional antiplatelet agents such as ].<ref name="Antman-2004"/> These agents are typically not started until the patient is evaluated by an emergency room physician or under the direction of a cardiologist. These agents can be used regardless of the reperfusion strategy that is to be employed. While these agents can decrease mortality in the setting of an acute myocardial infarction, they can lead to complications and potentially death if used in the wrong setting.

] associated myocardial infarction should be managed in a manner similar to other patients with acute coronary syndrome except ]s should not be used and ] should be administered early.<ref>{{cite journal |author=McCord J, Jneid H, Hollander JE, ''et al'' |title=Management of cocaine-associated chest pain and myocardial infarction: a scientific statement from the American Heart Association Acute Cardiac Care Committee of the Council on Clinical Cardiology |journal=Circulation |volume=117 |issue=14 |pages=1897–907 |year=2008 |month=April |pmid=18347214 |doi=10.1161/CIRCULATIONAHA.107.188950 |url=}}</ref>

===Reperfusion===
The concept of reperfusion has become so central to the modern treatment of acute myocardial infarction, that we are said to be in the reperfusion era.<ref name="Reperfusion_Era_30_Day_Mortality">Lee KL, Woodlief LH, Topol EJ, et al. "Predictors of 30-Day Mortality in the Era of Reperfusion for Acute Myocardial Infarction." ''Circulation'' 1995; '''91''': 1659-1668. PMID 7882472</ref><ref name="Reperfusion_Era_PAMI">Stone GW, Grines CL, Browne KF, et al. "Predictors of in-hospital and 6-month outcome after acute myocardial infarction in the reperfusion era: the Primary Angioplasty in Myocardial Infarction (PAMI) trail." ''J Am Coll Cardiol'' 1995; '''25''': 370-377. PMID 14645641</ref> Patients who present with suspected acute myocardial infarction and ST segment elevation (STEMI) or new bundle branch block on the 12 lead ] are presumed to have an occlusive thrombosis in an epicardial coronary artery. They are therefore candidates for immediate reperfusion, either with ], ] (PCI) or when these therapies are unsuccessful, ].

Individuals without ST segment elevation are presumed to be experiencing either unstable angina (UA) or non-ST segment elevation myocardial infarction (NSTEMI). They receive many of the same initial therapies and are often stabilized with ]s and ]. If their condition remains (]) stable, they can be offered either late ] with subsequent restoration of blood flow (revascularization), or ] ] to determine if there is significant ischemia that would benefit from revascularization. If hemodynamic instability develops in individuals with NSTEMIs, they may undergo urgent coronary angiography and subsequent revascularization. The use of thrombolytic agents is contraindicated in this patient subset, however.<ref name="FTT_Lancet">"Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Fibrinolytic Therapy Trialists' (FTT) Collaborative Group." ''Lancet'' 1994; '''343'''(8893): 311-22. PMID 7905143</ref>

The basis for this distinction in treatment regimens is that ST segment elevations on an ECG are typically due to complete occlusion of a coronary artery. On the other hand, in NSTEMIs there is typically a sudden narrowing of a coronary artery with preserved (but diminished) flow to the distal myocardium. Anticoagulation and antiplatelet agents are given to prevent the narrowed artery from occluding.

At least 10% of patients with STEMI don't develop myocardial necrosis (as evidenced by a rise in cardiac markers) and subsequent Q waves on EKG after reperfusion therapy. Such a successful restoration of flow to the infarct-related artery during an acute myocardial infarction is known as "aborting" the myocardial infarction. If treated within the hour, about 25% of STEMIs can be aborted.<ref name=Verheught2006>Verheugt FW, Gersh BJ, Armstrong PW. "Aborted myocardial infarction: a new target for reperfusion therapy." ''Eur Heart J'' 2006; '''27'''(8): 901-4. PMID 16543251</ref>

====Thrombolytic therapy====
{{Main|Thrombolysis}} {{Main|Thrombolysis}}
If PCI cannot be performed within 90 to 120 minutes in STEMI then fibrinolysis, preferably within 30 minutes of arrival to hospital, is recommended.<ref name=Reed2017 /><ref>{{cite journal | vauthors = Lassen JF, Bøtker HE, Terkelsen CJ | title = Timely and optimal treatment of patients with STEMI | journal = Nature Reviews. Cardiology | volume = 10 | issue = 1 | pages = 41–8 | date = January 2013 | pmid = 23165072 | doi = 10.1038/nrcardio.2012.156 | series = 1 | s2cid = 21955018 }}</ref> If a person has had symptoms for 12 to 24 hours evidence for effectiveness of thrombolysis is less and if they have had symptoms for more than 24 hours it is not recommended.<ref>{{cite journal | vauthors = Neumar RW, Shuster M, Callaway CW, Gent LM, Atkins DL, Bhanji F, Brooks SC, de Caen AR, Donnino MW, Ferrer JM, Kleinman ME, Kronick SL, Lavonas EJ, Link MS, Mancini ME, Morrison LJ, O'Connor RE, Samson RA, Schexnayder SM, Singletary EM, Sinz EH, Travers AH, Wyckoff MH, Hazinski MF | display-authors = 6 | title = Part 1: Executive Summary: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S315–67 | date = November 2015 | pmid = 26472989 | doi = 10.1161/cir.0000000000000252 | doi-access = free }}</ref> Thrombolysis involves the administration of medication that activates the ]. These medications include ], ], ], and ].<ref name=Harrisons2015 /> Thrombolysis is not recommended in a number of situations, particularly when associated with a high risk of bleeding or the potential for problematic bleeding, such as active bleeding, past ]s or bleeds into the brain, or severe ]. Situations in which thrombolysis may be considered, but with caution, include recent surgery, use of anticoagulants, pregnancy, and proclivity to bleeding.<ref name=Harrisons2015 /> Major risks of thrombolysis are major bleeding and ]ing.<ref name=Harrisons2015 /> Pre-hospital thrombolysis reduces time to thrombolytic treatment, based on studies conducted in higher income countries; however, it is unclear whether this has an impact on mortality rates.<ref name="mccaul">{{cite journal | vauthors = McCaul M, Lourens A, Kredo T | title = Pre-hospital versus in-hospital thrombolysis for ST-elevation myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 2014 | issue = 9 | pages = CD010191 | date = September 2014 | pmid = 25208209 | pmc = 6823254 | doi = 10.1002/14651858.CD010191.pub2 }}</ref>
Thrombolytic therapy is indicated for the treatment of STEMI if the drug can be administered within 12 hours of the onset of symptoms, the patient is eligible based on exclusion criteria, and primary PCI is not immediately available.<ref name="Antman-2004"/> The effectiveness of ] is highest in the first 2 hours. After 12 hours, the risk associated with thrombolytic therapy outweighs any benefit.<ref name="FTT_Lancet"/><ref name="Golden_Hour_Lancet">Boersma E, Maas AC, Deckers JW, Simoons ML. "Early thrombolytic treatment in acute myocardial infarction: reappraisal of the golden hour." ''Lancet'' 1996; '''348''' (9030): 771-5. PMID 8813982</ref> Because irreversible injury occurs within 2–4 hours of the infarction, there is a limited window of time available for reperfusion to work.


=== Other ===
Thrombolytic drugs are contraindicated for the treatment of unstable angina and NSTEMI<ref name="FTT_Lancet"/><ref name="TIMI_IIIB">"Effects of tissue plasminogen activator and a comparison of early invasive and conservative strategies in unstable angina and non-Q-wave myocardial infarction. Results of the TIMI IIIB Trial. Thrombolysis in Myocardial Ischemia." ''Circulation'' 1994; '''89''' (4): 1545-56. PMID 8149520</ref> and for the treatment of individuals with evidence of ].<ref name="Hochman-1999">{{cite journal | author=Hochman JS, Sleeper LA, Webb JG, Sanborn TA, White HD, Talley JD, Buller CE, Jacobs AK, Slater JN, Col J, McKinlay SM, LeJemtel TH. | title=Early revascularization in acute myocardial infarction complicated by cardiogenic shock. SHOCK Investigators. Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock | journal=N Engl J Med | year=1999 | volume=341 | issue=9 | pages=625–34 | pmid=10460813 | doi=10.1056/NEJM199908263410901}}</ref>
In the past, high flow oxygen was recommended for everyone with a possible myocardial infarction.<ref name=AHANSTEMI2014 /> More recently, no evidence was found for routine use in those with normal oxygen levels and there is potential harm from the intervention.<ref>{{cite journal | vauthors = Cabello JB, Burls A, Emparanza JI, Bayliss SE, Quinn T | title = Oxygen therapy for acute myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | pages = CD007160 | date = December 2016 | issue = 12 | pmid = 27991651 | pmc = 6463792 | doi = 10.1002/14651858.CD007160.pub4 }}</ref><ref>{{cite journal | vauthors = Hofmann R, James SK, Jernberg T, Lindahl B, Erlinge D, Witt N, Arefalk G, Frick M, Alfredsson J, Nilsson L, Ravn-Fischer A, Omerovic E, Kellerth T, Sparv D, Ekelund U, Linder R, Ekström M, Lauermann J, Haaga U, Pernow J, Östlund O, Herlitz J, Svensson L | display-authors = 6 | title = Oxygen Therapy in Suspected Acute Myocardial Infarction | journal = The New England Journal of Medicine | volume = 377 | issue = 13 | pages = 1240–1249 | date = September 2017 | pmid = 28844200 | doi = 10.1056/nejmoa1706222 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Abuzaid A, Fabrizio C, Felpel K, Al Ashry HS, Ranjan P, Elbadawi A, Mohamed AH, Barssoum K, Elgendy IY | display-authors = 6 | title = Oxygen Therapy in Patients with Acute Myocardial Infarction: A Systemic Review and Meta-Analysis | journal = The American Journal of Medicine | volume = 131 | issue = 6 | pages = 693–701 | date = June 2018 | pmid = 29355510 | doi = 10.1016/j.amjmed.2017.12.027 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Sepehrvand N, James SK, Stub D, Khoshnood A, Ezekowitz JA, Hofmann R | title = Effects of supplemental oxygen therapy in patients with suspected acute myocardial infarction: a meta-analysis of randomised clinical trials | journal = Heart | volume = 104 | issue = 20 | pages = 1691–1698 | date = October 2018 | pmid = 29599378 | doi = 10.1136/heartjnl-2018-313089 | s2cid = 4472549 }}</ref><ref>{{cite journal | vauthors = Singh A, Hussain S, Antony B | title = How Much Evidence Is Needed to Conclude against the Use of Oxygen Therapy in Acute Myocardial Infarction? | journal = Res Pract Thromb Haemost. | date = 2020 | volume = 4 | issue = Suppl 1 | url = https://abstracts.isth.org/abstract/how-much-evidence-is-needed-to-conclude-against-the-use-of-oxygen-therapy-in-acute-myocardial-infarction/ | access-date = 28 July 2020 }}</ref> Therefore, oxygen is currently only recommended if oxygen levels are found to be low or if someone is in respiratory distress.<ref name=Harrisons2015 /><ref name=AHANSTEMI2014 />


If despite thrombolysis there is significant ], continued severe chest pain, or less than a 50% improvement in ] on the ECG recording after 90 minutes, then rescue PCI is indicated emergently.<ref name=Wang2011>{{cite book|vauthors=Ardehali R, Perez M, Wang P |title=A practical approach to cardiovascular medicine|publisher=Wiley-Blackwell|location=Chichester, West Sussex, UK|isbn=978-1-4443-9387-3|year=2011|page=57|url=https://books.google.com/books?id=LZsoHMN8lM4C&pg=PA57}}</ref><ref>{{cite book|veditors=Jindal SK |title=Textbook of pulmonary and critical care medicine|publisher=Jaypee Brothers Medical Publishers|location=New Delhi|isbn=978-93-5025-073-0|year=2011|page=1758|url=https://books.google.com/books?id=rAT1bdnDakAC&pg=PA1758}}</ref>
Although no perfect thrombolytic agent exists, an ideal thrombolytic drug would lead to rapid reperfusion, have a high sustained patency rate, be specific for recent thrombi, be easily and rapidly administered, create a low risk for intra-cerebral and systemic bleeding, have no antigenicity, adverse hemodynamic effects, or clinically significant drug interactions, and be cost effective.<ref name="Ideal_Thrombolytic">White HD, Van de Werf FJ. "Thrombolysis for acute myocardial infarction.." ''Circulation'' 1998; '''97''' (16): 1632-46. PMID 9593569</ref> Currently available thrombolytic agents include ], ], and ] (recombinant ], rtPA). More recently, thrombolytic agents similar in structure to rtPA such as ] and ] have been used. These newer agents boast efficacy at least as good as rtPA with significantly easier administration. The thrombolytic agent used in a particular individual is based on institution preference and the age of the patient.


Those who have had ] may benefit from ] with evaluation for implementation of hypothermia protocols. Furthermore, those with cardiac arrest, and ST elevation at any time, should usually have angiography.<ref name=AHA2013 /> ] appear to be useful in people who have had an STEMI and do not have heart failure.<ref>{{cite journal | vauthors = Dahal K, Hendrani A, Sharma SP, Singireddy S, Mina G, Reddy P, Dominic P, Modi K | display-authors = 6 | title = Aldosterone Antagonist Therapy and Mortality in Patients With ST-Segment Elevation Myocardial Infarction Without Heart Failure: A Systematic Review and Meta-analysis | journal = JAMA Internal Medicine | volume = 178 | issue = 7 | pages = 913–920 | date = July 2018 | pmid = 29799995 | pmc = 6145720 | doi = 10.1001/jamainternmed.2018.0850 }}</ref>
Depending on the thrombolytic agent being used, ] anticoagulation with ] or ] may be of benefit.<ref name="GUSTO-1993-1">{{cite journal | author=The GUSTO investigators | title=An international randomized trial comparing four thrombolytic strategies for acute myocardial infarction. The GUSTO investigators | journal=N Engl J Med | year=1993 | volume=329 | issue=10 | pages=673–82 | pmid=8204123 | doi=10.1056/NEJM199309023291001}}</ref><ref name="Sabatine-2005">{{cite journal | author=Sabatine MS, Morrow DA, Montalescot G, Dellborg M, Leiva-Pons JL, Keltai M, Murphy SA, McCabe CH, Gibson CM, Cannon CP, Antman EM, Braunwald E; Clopidogrel as Adjunctive Reperfusion Therapy (CLARITY)-Thrombolysis in Myocardial Infarction (TIMI) 28 Investigators. | title=Angiographic and clinical outcomes in patients receiving low-molecular-weight heparin versus unfractionated heparin in ST-elevation myocardial infarction treated with fibrinolytics in the CLARITY-TIMI 28 Trial | journal=Circulation | year=2005 | volume=112 | issue=25 | pages=3846–54 | pmid=16291601 | doi = 10.1161/CIRCULATIONAHA.105.595397}}</ref> With TPa and related agents (reteplase and tenecteplase), heparin is needed to maintain coronary artery patency. Because of the anticoagulant effect of fibrinogen depletion with streptokinase<ref name="Cowley-1983">{{cite journal | author=Cowley MJ, Hastillo A, Vetrovec GW, Fisher LM, Garrett R, Hess ML. | title=Fibrinolytic effects of intracoronary streptokinase administration in patients with acute myocardial infarction and coronary insufficiency | journal=Circulation | year=1983 | volume=67 | issue=5 | pages=1031–8 | pmid=6831667}}</ref> and urokinase<ref name="Lourenco-1989">{{cite journal | author=Lourenco DM, Dosne AM, Kher A, Samama M. | title=Effect of standard heparin and a low molecular weight heparin on thrombolytic and fibrinolytic activity of single-chain urokinase plasminogen activator ''in vitro'' | journal=Thromb Haemost | year=1989 | volume=62 | issue=3 | pages=923–6 | pmid=2556812}}</ref><ref name="Van de Werf-1986">{{cite journal | author=Van de Werf F, Vanhaecke J, de Geest H, Verstraete M, Collen D. | title=Coronary thrombolysis with recombinant single-chain urokinase-type plasminogen activator in patients with acute myocardial infarction | journal=Circulation | year=1986 | volume=74 | issue=5 | pages=1066–70 | pmid=2429783}}</ref><ref name="Bode-1988">{{cite journal | author=Bode C, Schoenermark S, Schuler G, Zimmermann R, Schwarz F, Kuebler W. | title=Efficacy of intravenous prourokinase and a combination of prourokinase and urokinase in acute myocardial infarction | journal=Am J Cardiol | year=1988 | volume=61 | issue=13 | pages=971–4 | pmid=2452564 | doi = 10.1016/0002-9149(88)90108-7}}</ref> treatment, it is less necessary there.<ref name="GUSTO-1993-1"/>


=== Rehabilitation and exercise ===
Intracranial bleeding (ICB) and subsequent ] (CVA) is a serious side effect of thrombolytic use. The risk of ICB is dependent on a number of factors, including a previous episode of intracranial bleed, age of the individual, and the thrombolytic regimen that is being used. In general, the risk of ICB due to thrombolytic use for the treatment of an acute myocardial infarction is between 0.5 and 1 percent.<ref name="GUSTO-1993-1" />
] benefits many who have experienced myocardial infarction,<ref name=Reed2017 /> even if there has been substantial heart damage and resultant ]. It should start soon after discharge from the hospital. The program may include lifestyle advice, exercise, social support, as well as recommendations about driving, flying, sports participation, stress management, and sexual intercourse.<ref name=NICE172>{{NICE|172|Secondary prevention in primary and secondary care for patients following a myocardial infarction|2013}}</ref> Returning to sexual activity after myocardial infarction is a major concern for most patients, and is an important area to be discussed in the provision of holistic care.<ref>{{cite journal | vauthors = Rahim L, Allana S, Steinke EE, Ali F, Khan AH | title = Level of knowledge among cardiac nurses regarding sexual counseling of post-MI patients in three tertiary care hospitals in Pakistan | journal = Heart & Lung | volume = 46 | issue = 6 | pages = 412–416 | date = November 2017 | pmid = 28988654 | doi = 10.1016/j.hrtlng.2017.09.002 | s2cid = 4277993 }}</ref><ref name="pmid20168196">{{cite journal | vauthors = Jaarsma T, Steinke EE, Gianotten WL | title = Sexual problems in cardiac patients: how to assess, when to refer | journal = The Journal of Cardiovascular Nursing | volume = 25 | issue = 2 | pages = 159–64 | date = 2010 | pmid = 20168196 | doi = 10.1097/JCN.0b013e3181c60e7c | s2cid = 25806176 }}</ref>


In the short-term, exercise-based cardiovascular rehabilitation programs may reduce the risk of a myocardial infarction, reduces a large number of hospitalizations from all causes, reduces hospital costs, improves ], and has a small effect on ].<ref>{{cite journal | vauthors = Dibben G, Faulkner J, Oldridge N, Rees K, Thompson DR, Zwisler AD, Taylor RS | title = Exercise-based cardiac rehabilitation for coronary heart disease | journal = The Cochrane Database of Systematic Reviews | volume = 2021 | issue = 11 | pages = CD001800 | date = November 2021 | pmid = 34741536 | pmc = 8571912 | doi = 10.1002/14651858.CD001800.pub4 }}</ref> Longer-term studies indicate that exercise-based cardiovascular rehabilitation programs may reduce cardiovascular mortality and myocardial infarction.
Thrombolytic therapy to abort a myocardial infarction is not always effective. The degree of effectiveness of a thrombolytic agent is dependent on the time since the myocardial infarction began, with the best results occurring if the thrombolytic agent is used within two hours of the onset of symptoms.<ref name="Boersma-1996">{{cite journal | author=Boersma E, Maas AC, Deckers JW, Simoons ML. | title=Early thrombolytic treatment in acute myocardial infarction: reappraisal of the golden hour | journal=Lancet | year=1996 | volume=348 | issue=9030 | pages=771–5 | pmid=8813982 | doi = 10.1016/S0140-6736(96)02514-7}}</ref><ref name="Morrison-2000"/> If the individual presents more than 12 hours after symptoms commenced, the risk of intracranial bleed are considered higher than the benefits of the thrombolytic agent.<ref name="LATE-1993">{{cite journal | author=LATE trial intestigatos. | title=Late Assessment of Thrombolytic Efficacy (LATE) study with alteplase 6-24 hours after onset of acute myocardial infarction | journal=Lancet | year=1993 | volume=342 | issue=8874 | pages=759–66 | pmid=8103874 | doi=10.1016/0140-6736(93)91538-W}}</ref> Failure rates of thrombolytics can be as high as 20% or higher.<ref name="Chesebro-1987">{{cite journal | author=Chesebro JH, Knatterud G, Roberts R, Borer J, Cohen LS, Dalen J, Dodge HT, Francis CK, Hillis D, Ludbrook P, et al. | title=Thrombolysis in Myocardial Infarction (TIMI) Trial, Phase I: A comparison between intravenous tissue plasminogen activator and intravenous streptokinase. Clinical findings through hospital discharge | journal=Circulation | year=1987| volume=76 | issue=1 | pages=142–54 | pmid=3109764}}</ref> In cases of failure of the thrombolytic agent to open the infarct-related coronary artery, the patient is then either treated conservatively with anticoagulants and allowed to "complete the infarction" or ] (PCI, see below) is then performed. Percutaneous coronary intervention in this setting is known as "rescue PCI" or "salvage PCI". Complications, particularly bleeding, are significantly higher with rescue PCI than with primary PCI due to the action of the thrombolytic agent.


== Prognosis ==
====Percutaneous coronary intervention====
The prognosis after myocardial infarction varies greatly depending on the extent and location of the affected heart muscle, and the development and management of complications.<ref name=Davidsons2010 /> Prognosis is worse with older age and social isolation.<ref name=Davidsons2010 /> Anterior infarcts, persistent ventricular tachycardia or fibrillation, development of ]s, and left ventricular impairment are all associated with poorer prognosis.<ref name=Davidsons2010 /> Without treatment, about a quarter of those affected by MI die within minutes and about forty percent within the first month.<ref name=Davidsons2010 /> Morbidity and mortality from myocardial infarction has, however, improved over the years due to earlier and better treatment:<ref name=Harrisons2015B /> in those who have a STEMI in the United States, between 5 and 6&nbsp;percent die before leaving the hospital and 7 to 18&nbsp;percent die within a year.<ref name=AHA2013 />
{{main|Percutaneous coronary intervention}}
] material (in a cup, upper left corner) removed from a coronary artery during a ] to abort a myocardial infarction. Five pieces of thrombus are shown (arrow heads).]]
The benefit of prompt, expertly performed primary percutaneous coronary intervention over thrombolytic therapy for acute ST elevation myocardial infarction is now well established.<ref name="Keeley-2003">{{cite journal | author=Keeley EC, Boura JA, Grines CL. | title=Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomised trials | journal=Lancet | year=2003 | volume=361 | issue=9351 | pages=13–20 | pmid=12517460 | doi = 10.1016/S0140-6736(03)12113-7}}</ref><ref name="Grines-1993">{{cite journal | author=Grines CL, Browne KF, Marco J, Rothbaum D, Stone GW, O'Keefe J, Overlie P, Donohue B, Chelliah N, Timmis GC, et al. | title=A comparison of immediate angioplasty with thrombolytic therapy for acute myocardial infarction. The Primary Angioplasty in Myocardial Infarction Study Group | journal=N Engl J Med | year=1993 | volume=328 | issue=10 | pages=673–9 | pmid=8433725 | doi = 10.1056/NEJM199303113281001}}</ref><ref name="GUSTO-IIb">{{cite journal | author=The Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO IIb) Angioplasty Substudy Investigators. | title=A clinical trial comparing primary coronary angioplasty with tissue plasminogen activator for acute myocardial infarction | journal=N Engl J Med | year=1997 | volume=336 | issue=23 | pages=1621–8 | pmid=9173270 | doi=10.1056/NEJM199706053362301}}</ref> When performed rapidly by an experienced team, primary PCI restores flow in the culprit artery in more than 95% of patients compared with the spontaneous recanalization rate of about 65%.<ref name="Keeley-2003"/> Logistic and economic obstacles seem to hinder a more widespread application of ] (PCI) via ],<ref name=Boersma2006>Boersma E; The Primary Coronary Angioplasty vs. Thrombolysis Group. "Does time matter? A pooled analysis of randomized clinical trials comparing primary percutaneous coronary intervention and in-hospital fibrinolysis in acute myocardial infarction patients." ''Eur Heart J'' 2006; '''27'''(7):779-88. PMID 16513663</ref> although the feasibility of regionalized PCI for STEMI is currently being explored in the United States.<ref name=Rokos_2006>Rokos IC, Larson DM, Henry TD, et al.; "Rationale for establishing regional ST-elevation myocardial infarction receiving center (SRC) networks." ''Am Heart J'' 2006; '''152'''(4):661-7. PMID 16996830</ref> The use of percutaneous coronary intervention as a therapy to abort a myocardial infarction is known as primary PCI. The goal of primary PCI is to open the artery as soon as possible, and preferably within 90 minutes of the patient presenting to the emergency room. This time is referred to as the ] time. Few hospitals can provide PCI within the 90 minute interval,<ref name=Doortoballoon>Bradley EH, Herrin J, Wang Y, Barton BA, Webster TR, Mattera JA, Roumanis SA, Curtis JP, Nallamothu BK, Magid DJ, McNamara RL, Parkosewich J, Loeb JM, Krumholz HM. "Strategies for reducing the door-to-balloon time in acute myocardial infarction." ''N Engl J Med'' 2006; '''355'''(22): 2308-20. PMID 17101617</ref> which prompted the American College of Cardiology (ACC) to launch a national Door to Balloon (D2B) Initiative in November 2006. Over 800 hospitals have joined the D2B Alliance as of March 16, 2007.<ref name="ACC-D2B">{{cite web | title=D2B: An Alliance for Quality | publisher=American College of Cardiology | date=2006 | url=http://d2b.acc.org/ | dateformat=mdy | accessdate=April 15 2007}}</ref>


It is unusual for babies to experience a myocardial infarction, but when they do, about half die.<ref name=":0">{{cite journal | vauthors = Papneja K, Chan AK, Mondal TK, Paes B | title = Myocardial Infarction in Neonates: A Review of an Entity with Significant Morbidity and Mortality | journal = Pediatric Cardiology | volume = 38 | issue = 3 | pages = 427–441 | date = March 2017 | pmid = 28238152 | doi = 10.1007/s00246-016-1556-7 | s2cid = 20779415 }}</ref> In the short-term, neonatal survivors seem to have a normal quality of life.<ref name=":0" />
One particularly successful implementation of a primary PCI protocol is in the ] under the auspices of the ]. Under this model, EMS teams responding to an emergency electronically transmit the ECG directly to a digital archiving system that allows emergency room physicians and/or cardiologists to immediately confirm the diagnosis. This in turn allows for redirection of the EMS teams to facilities prepped to conduct time-critical angioplasty, based on the ECG analysis. In an article published in the ] in June 2007, the Calgary implementation resulted in a median time to treatment of 62 minutes.<ref name="De Villiers-2007">{{cite journal | author = De Villiers JS, Anderson T, McMeekin JD, ''et al''. | title = Expedited transfer for primary percutaneous coronary intervention: a program evaluation | journal = CMAJ | volume = 176 | pages = 1833–8 | year = 2007 | pmid = 17576980}}</ref>


=== Complications ===
The current guidelines in the United States restrict primary PCI to hospitals with available emergency bypass surgery as a backup,<ref name="Antman-2004"/> but this is not the case in other parts of the world.<ref name="Aversano-2001">{{cite journal | author = Aversano T ''et al''. | title = Thrombolytic therapy vs primary percutaneous coronary intervention for myocardial infarction in patients presenting to hospitals without on-site cardiac surgery: a randomized controlled trial | journal = JAMA | volume = 287 | issue = 15 | pages = 1943–51 | year = 2002 | pmid = 11960536 | doi = 10.1001/jama.287.15.1943}}</ref>
{{Main|Myocardial infarction complications}}
Complications may occur immediately following the myocardial infarction or may take time to develop. ], including ], ] and ] and ] can arise as a result of ischemia, cardiac scarring, and infarct location.<ref name=Davidsons2010 /><ref name=Reed2017 /> ] is also a risk, either as a result of ] transmitted from the heart during PCI, as a result of bleeding following anticoagulation, or as a result of disturbances in the heart's ability to pump effectively as a result of the infarction.<ref name=Reed2017 /> ] is possible, particularly if the infarction causes dysfunction of the papillary muscle.<ref name=Reed2017 /> ] as a result of the heart being unable to adequately pump blood may develop, dependent on infarct size, and is most likely to occur within the days following an acute myocardial infarction. Cardiogenic shock is the largest cause of in-hospital mortality.<ref name=Harrisons2015B /><ref name=Reed2017 /> Rupture of the ventricular dividing wall or left ventricular wall may occur within the initial weeks.<ref name=Reed2017 /> ], a reaction following larger infarcts and a cause of ] is also possible.<ref name=Reed2017 />


] may develop as a long-term consequence, with an impaired ability of heart muscle to pump, scarring, and an increase in the size of the existing muscle. ] develops in about 10% of MI and is itself a risk factor for heart failure, ventricular arrhythmia, and the development of ].<ref name=Davidsons2010 />
Primary PCI involves performing a coronary ] to determine the anatomical location of the infarcting vessel, followed by balloon ] (and frequently deployment of an intracoronary stent) of the thrombosed arterial segment. In some settings, an extraction catheter may be used to attempt to aspirate (remove) the thrombus prior to balloon angioplasty. While the use of intracoronary ]s do not improve the short term outcomes in primary PCI, the use of stents is widespread because of the decreased rates of procedures to treat restenosis compared to balloon angioplasty.<ref name="Grines-1999">{{cite journal | author=Grines CL, Cox DA, Stone GW, Garcia E, Mattos LA, Giambartolomei A, Brodie BR, Madonna O, Eijgelshoven M, Lansky AJ, O'Neill WW, Morice MC. | title=Coronary angioplasty with or without stent implantation for acute myocardial infarction. Stent Primary Angioplasty in Myocardial Infarction Study Group | journal=N Engl J Med | year=1999 | volume=341 | issue=26 | pages=1949–56 | pmid=10607811 | doi=10.1056/NEJM199912233412601}}</ref>


Risk factors for complications and death include age, ] parameters (such as ], ] on admission, ] ], or ] of two or greater), ST-segment deviation, diabetes, serum ], ], and elevation of cardiac markers.<ref name="PEPA">{{cite journal | vauthors = López de Sá E, López-Sendón J, Anguera I, Bethencourt A, Bosch X | title = Prognostic value of clinical variables at presentation in patients with non-ST-segment elevation acute coronary syndromes: results of the Proyecto de Estudio del Pronóstico de la Angina (PEPA) | journal = Medicine | volume = 81 | issue = 6 | pages = 434–42 | date = November 2002 | pmid = 12441900 | doi = 10.1097/00005792-200211000-00004 | author6 = Proyecto de Estudio del Pronostico de la Angina (PEPA) Investigators | s2cid = 10268606 | doi-access = free | hdl = 20.500.13003/14561 | hdl-access = free }}</ref><ref name="GRACE">{{cite journal | vauthors = Fox KA, Dabbous OH, Goldberg RJ, Pieper KS, Eagle KA, Van de Werf F, Avezum A, Goodman SG, Flather MD, Anderson FA, Granger CB | display-authors = 6 | title = Prediction of risk of death and myocardial infarction in the six months after presentation with acute coronary syndrome: prospective multinational observational study (GRACE) | journal = BMJ | volume = 333 | issue = 7578 | pages = 1091 | date = November 2006 | pmid = 17032691 | pmc = 1661748 | doi = 10.1136/bmj.38985.646481.55 }}</ref><ref name="Weir-2006">{{cite journal | vauthors = Weir RA, McMurray JJ, Velazquez EJ | title = Epidemiology of heart failure and left ventricular systolic dysfunction after acute myocardial infarction: prevalence, clinical characteristics, and prognostic importance | journal = The American Journal of Cardiology | volume = 97 | issue = 10A | pages = 13F–25F | date = May 2006 | pmid = 16698331 | doi = 10.1016/j.amjcard.2006.03.005 }}</ref>
Adjuvant therapy during primary PCI include intravenous ], ], and ]. The use of ]s are often used in the setting of primary PCI to reduce the risk of ischemic complications during the procedure.<ref name="Brener-1998">{{cite journal | author=Brener SJ, Barr LA, Burchenal JE, Katz S, George BS, Jones AA, Cohen ED, Gainey PC, White HJ, Cheek HB, Moses JW, Moliterno DJ, Effron MB, Topol EJ. | title=Randomized, placebo-controlled trial of platelet glycoprotein IIb/IIIa blockade with primary angioplasty for acute myocardial infarction. ReoPro and Primary PTCA Organization and Randomized Trial (RAPPORT) Investigators | journal=Circulation | year=1998 | volume=98 | issue=8 | pages=734–41 | pmid=9727542}}</ref><ref name="Tcheng-2003-1">{{cite journal | author=Tcheng JE, Kandzari DE, Grines CL, Cox DA, Effron MB, Garcia E, Griffin JJ, Guagliumi G, Stuckey T, Turco M, Fahy M, Lansky AJ, Mehran R, Stone GW; CADILLAC Investigators. | title=Benefits and risks of abciximab use in primary angioplasty for acute myocardial infarction: the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial | journal=Circulation | year=2003 | volume=108 | issue=11 | pages=1316–23 | pmid=12939213 | doi = 10.1161/01.CIR.0000087601.45803.86}}</ref> Due to the number of antiplatelet agents and anticoagulants used during primary PCI, the risk of bleeding associated with the procedure are higher than during an elective PCI.<ref>{{cite book |title=900 Questions: An Interventional Cardiology Board Review |last=Mukherjee |first=Debabrata |year=2006 |publisher=Lippincott Williams & Wilkins |isbn=0781773490 }} </ref>


== Epidemiology ==
====Coronary artery bypass surgery====
Myocardial infarction is a common presentation of ]. The ] estimated in 2004, that 12.2% of worldwide deaths were from ischemic heart disease;<ref name="WHO-2004">{{cite book |author=World Health Organization |title=The Global Burden of Disease: 2004 Update |publisher=World Health Organization |location=Geneva |year=2008 |isbn=978-92-4-156371-0 }}</ref> with it being the leading cause of death in high- or middle-income countries and second only to ] in ].<ref name="WHO-2004" /> Worldwide, more than 3 million people have STEMIs and 4 million have NSTEMIs a year.<ref name="Lancet08" /> STEMIs occur about twice as often in men as women.<ref name=AHA2013 />
{{Main|Coronary artery bypass graft surgery}}
] from its surrounding tissue, ] (yellow). The tube visible at the bottom is the aortic cannula (returns blood from the ]). The tube above it (obscured by the ] on the right) is the venous cannula (receives blood from the body). The patient's ] is stopped and the ] is cross-clamped. The patient's head (not seen) is at the bottom.]]


Rates of death from ischemic heart disease (IHD) have slowed or declined in most high-income countries, although cardiovascular disease still accounted for one in three of all deaths in the US in 2008.<ref>{{cite journal | vauthors = Roger VL, Go AS, Lloyd-Jones DM, Benjamin EJ, Berry JD, Borden WB, Bravata DM, Dai S, Ford ES, Fox CS, Fullerton HJ, Gillespie C, Hailpern SM, Heit JA, Howard VJ, Kissela BM, Kittner SJ, Lackland DT, Lichtman JH, Lisabeth LD, Makuc DM, Marcus GM, Marelli A, Matchar DB, Moy CS, Mozaffarian D, Mussolino ME, Nichol G, Paynter NP, Soliman EZ, Sorlie PD, Sotoodehnia N, Turan TN, Virani SS, Wong ND, Woo D, Turner MB | display-authors = 6 | collaboration = American Heart Association Statistics Committee and Stroke Statistics Subcommittee | title = Executive summary: heart disease and stroke statistics--2012 update: a report from the American Heart Association | journal = Circulation | volume = 125 | issue = 1 | pages = 188–97 | date = January 2012 | pmid = 22215894 | doi = 10.1161/CIR.0b013e3182456d46 | doi-access = free }}</ref> For example, rates of death from cardiovascular disease have decreased almost a third between 2001 and 2011 in the United States.<ref>{{cite journal | vauthors = Mozaffarian D, Benjamin EJ, Go AS, Arnett DK, Blaha MJ, Cushman M, de Ferranti S, Després JP, Fullerton HJ, Howard VJ, Huffman MD, Judd SE, Kissela BM, Lackland DT, Lichtman JH, Lisabeth LD, Liu S, Mackey RH, Matchar DB, McGuire DK, Mohler ER, Moy CS, Muntner P, Mussolino ME, Nasir K, Neumar RW, Nichol G, Palaniappan L, Pandey DK, Reeves MJ, Rodriguez CJ, Sorlie PD, Stein J, Towfighi A, Turan TN, Virani SS, Willey JZ, Woo D, Yeh RW, Turner MB | display-authors = 6 | title = Heart disease and stroke statistics--2015 update: a report from the American Heart Association | journal = Circulation | volume = 131 | issue = 4 | pages = e29–322 | date = January 2015 | pmid = 25520374 | doi = 10.1161/cir.0000000000000152 | quote = From 2001 to 2011, death rates attributable to CVD declined 30.8%. | doi-access = free }}</ref>
Despite the guidelines, emergency bypass surgery for the treatment of an acute myocardial infarction (MI) is less common than PCI or medical management. In an analysis of patients in the U.S. ] (NRMI) from January 1995 to May 2004, the percentage of patients with ] treated with primary PCI rose from 27.4% to 54.4%, while the increase in CABG treatment was only from 2.1% to 3.2%.<ref name=NRMI>{{cite journal |author=Babaev A, Frederick PD, Pasta DJ, Every N, Sichrovsky T, Hochman JS |title=Trends in management and outcomes of patients with acute myocardial infarction complicated by cardiogenic shock |journal=JAMA |volume=294 |issue=4 |pages=448–54 |year=2005 |pmid=16046651 |doi=10.1001/jama.294.4.448 |url=http://jama.ama-assn.org/cgi/pmidlookup?view=long&pmid=16046651}}</ref>


In contrast, IHD is becoming a more common cause of death in the developing world. For example, in ], IHD had become the leading cause of death by 2004, accounting for 1.46 million deaths (14% of total deaths) and deaths due to IHD were expected to double during 1985–2015.<ref>{{cite journal | vauthors = Gupta R, Joshi P, Mohan V, Reddy KS, Yusuf S | title = Epidemiology and causation of coronary heart disease and stroke in India | journal = Heart | volume = 94 | issue = 1 | pages = 16–26 | date = January 2008 | pmid = 18083949 | doi = 10.1136/hrt.2007.132951 | s2cid = 27117207 }}</ref> Globally, ]s (DALYs) lost to ischemic heart disease are predicted to account for 5.5% of total DALYs in 2030, making it the second-most-important cause of disability (after ]), as well as the leading cause of death by this date.<ref name="WHO-2004" />
Emergency coronary artery bypass graft surgery (CABG) is usually undertaken to simultaneously treat a mechanical complication, such as a ruptured papillary muscle, or a ventricular septal defect, with ensueing cardiogenic shock.<ref name=Sabiston>{{cite book | last =Townsend | first =Courtney M. | coauthors =Beauchamp D.R., Evers M.B., Mattox K.L. | title =Sabiston Textbook of Surgery - The Biological Basis of Modern Surgical Practice | publisher =Elsevier Saunders | date =2004 | location =Philadelphia, Pennsylvania | pages =1871 | url =http://www.elsevier.com/wps/find/bookdescription.cws_home/701163/description#description | isbn =0-7216-0409-9}}</ref> In uncomplicated MI, the ] can be high when the surgery is performed immediately following the infarction.<ref name=Timing1>{{cite journal |author=Kaul TK, Fields BL, Riggins SL, Dacumos GC, Wyatt DA, Jones CR |title=Coronary artery bypass grafting within 30 days of an acute myocardial infarction |journal=Ann. Thorac. Surg. |volume=59 |issue=5 |pages=1169–76 |year=1995 |pmid=7733715 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/0003497595001255}}</ref> If this option is entertained, the patient should be stabilized prior to surgery, with supportive interventions such as the use of an ].<ref name=Timing2>{{cite journal |author=Creswell LL, Moulton MJ, Cox JL, Rosenbloom M |title=Revascularization after acute myocardial infarction |journal=Ann. Thorac. Surg. |volume=60 |issue=1 |pages=19–26 |year=1995 |pmid=7598589 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/000349759500351K}}</ref> In patients developing cardiogenic shock after a myocardial infarction, both PCI and CABG are satisfactory treatment options, with similar survival rates.<ref name=SHOCK>{{cite journal |author=White HD, Assmann SF, Sanborn TA, ''et al'' |title=Comparison of percutaneous coronary intervention and coronary artery bypass grafting after acute myocardial infarction complicated by cardiogenic shock: results from the Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial |journal=Circulation |volume=112 |issue=13 |pages=1992–2001 |year=2005 |pmid=16186436 |doi=10.1161/CIRCULATIONAHA.105.540948 |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=16186436}}</ref><ref name="Hochman-2006">{{cite journal | author=Hochman JS, Sleeper LA, Webb JG, Dzavik V, Buller CE, Aylward P, Col J, White HD; SHOCK Investigators. | title=Early revascularization and long-term survival in cardiogenic shock complicating acute myocardial infarction | journal=JAMA | year=2006 | volume=295 | issue=21 | pages=2511–5 | pmid=16757723 | doi = 10.1001/jama.295.21.2511}}</ref>


== Social determinants of health ==
Coronary artery bypass surgery involves an artery or vein from the patient being implanted to bypass ] or occlusions on the coronary arteries. Several arteries and veins can be used, however ] grafts have demonstrated significantly better long-term patency rates than ] grafts.<ref name=Raja2004>{{cite journal |author=Raja SG, Haider Z, Ahmad M, Zaman H |title=Saphenous vein grafts: to use or not to use? |journal=Heart Lung Circ |volume=13 |issue=4 |pages=403–9 |year=2004 |pmid=16352226 |doi=10.1016/j.hlc.2004.04.004 |url=http://linkinghub.elsevier.com/retrieve/pii/S1443-9506(04)00140-4}}</ref> In patients with two or more coronary arteries affected, bypass surgery is associated with higher long-term ]s compared to percutaneous interventions.<ref name=Hannan2005>{{cite journal |author=Hannan EL, Racz MJ, Walford G, ''et al'' |title=Long-term outcomes of coronary-artery bypass grafting versus stent implantation |journal=N. Engl. J. Med. |volume=352 |issue=21 |pages=2174–83 |year=2005 |pmid=15917382 |doi=10.1056/NEJMoa040316 |url=http://content.nejm.org/cgi/pmidlookup?view=short&pmid=15917382&promo=ONFLNS19}}</ref> In patients with single vessel disease, surgery is comparably safe and effective, and may be a treatment option in selected cases.<ref name=Bourassa2000>{{cite journal |author=Bourassa MG |title=Clinical trials of coronary revascularization: coronary angioplasty vs. coronary bypass grafting |journal=Curr. Opin. Cardiol. |volume=15 |issue=4 |pages=281–6 |year=2000 |pmid=11139092 |doi= |url=http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=0268-4705&volume=15&issue=4&spage=281}}</ref> Bypass surgery has higher costs initially, but becomes ] in the long term.<ref name=Hlatky2004>{{cite journal |author=Hlatky MA, Boothroyd DB, Melsop KA, ''et al'' |title=Medical costs and quality of life 10 to 12 years after randomization to angioplasty or bypass surgery for multivessel coronary artery disease |journal=Circulation |volume=110 |issue=14 |pages=1960–6 |year=2004 |pmid=15451795 |doi=10.1161/01.CIR.0000143379.26342.5C |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=15451795}}</ref> A surgical bypass graft is more ] initially but bears less risk of recurrent procedures (but these may be again ]).<ref name=Bourassa2000/>


{{globalize|section|date=October 2024}}
===Monitoring for arrhythmias===
Additional objectives are to prevent life-threatening arrhythmias or conduction disturbances. This requires monitoring in a ] and protocolised administration of ]s. Antiarrhythmic agents are typically only given to individuals with life-threatening arrhythmias after a myocardial infarction and not to suppress the ] that is often seen after a myocardial infarction.<ref name="Echt-1991">{{cite journal | author=Echt DS, Liebson PR, Mitchell LB, Peters RW, Obias-Manno D, Barker AH, Arensberg D, Baker A, Friedman L, Greene HL, ''et al.'' | title= Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial | journal= N Engl J Med | year= 1991 | volume= 324 | issue= 12 | pages= 781–8 | pmid=1900101}}</ref><ref name="Waldo-1996">{{cite journal | author=Waldo AL, Camm AJ, deRuyter H, Friedman PL, MacNeil DJ, Pauls JF, Pitt B, Pratt CM, Schwartz PJ, Veltri EP. | title=Effect of d-sotalol on mortality in patients with left ventricular dysfunction after recent and remote myocardial infarction. The SWORD Investigators. Survival With Oral d-Sotalol | journal=Lancet | year=1996 | volume=348 | issue=9019 | pages=7–12 | pmid=8691967 | doi = 10.1016/S0140-6736(96)02149-6}}</ref><ref name="Julian-1997">{{cite journal | author= Julian DG, Camm AJ, Frangin G, Janse MJ, Munoz A, Schwartz PJ, Simon P. | title= Randomised trial of effect of amiodarone on mortality in patients with left-ventricular dysfunction after recent myocardial infarction: EMIAT. European Myocardial Infarct Amiodarone Trial Investigators | journal= Lancet | year= 1997 | volume= 349 | issue= 9053 | pages= 667–74 | pmid=9078197 | doi = 10.1016/S0140-6736(96)09145-3}}</ref>


Social determinants such as ] disadvantage, ] status, lack of ], ], and access to ] play an important role in myocardial infarction risk and survival.<ref>{{cite journal | vauthors = Coady SA, Johnson NJ, Hakes JK, Sorlie PD | title = Individual education, area income, and mortality and recurrence of myocardial infarction in a Medicare cohort: the National Longitudinal Mortality Study | journal = BMC Public Health | volume = 14 | issue = 1 | pages = 705 | date = July 2014 | pmid = 25011538 | doi = 10.1186/1471-2458-14-705 | pmc = 4227052 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Salomaa V, Miettinen H, Niemelä M, Ketonen M, Mähönen M, Immonen-Räihä P, Lehto S, Vuorenmaa T, Koskinen S, Palomäki P, Mustaniemi H, Kaarsalo E, Arstila M, Torppa J, Kuulasmaa K, Puska P, Pyörälä K, Tuomilehto J | display-authors = 6 | title = Relation of socioeconomic position to the case fatality, prognosis and treatment of myocardial infarction events; the FINMONICA MI Register Study | journal = Journal of Epidemiology and Community Health | volume = 55 | issue = 7 | pages = 475–82 | date = July 2001 | pmid = 11413176 | doi = 10.1136/jech.55.7.475 | pmc = 1731938 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Bucholz EM, Ma S, Normand SL, Krumholz HM | title = Race, Socioeconomic Status, and Life Expectancy After Acute Myocardial Infarction | journal = Circulation | volume = 132 | issue = 14 | pages = 1338–46 | date = October 2015 | pmid = 26369354 | doi = 10.1161/circulationaha.115.017009 | pmc = 5097251 }}</ref><ref>{{cite journal | vauthors = Kilpi F, Silventoinen K, Konttinen H, Martikainen P | title = Disentangling the relative importance of different socioeconomic resources for myocardial infarction incidence and survival: a longitudinal study of over 300,000 Finnish adults | journal = European Journal of Public Health | volume = 26 | issue = 2 | pages = 260–6 | date = April 2016 | pmid = 26585783 | doi = 10.1093/eurpub/ckv202 | doi-access = free }}</ref> Studies have shown that low ] is associated with an increased risk of poorer survival. There are well-documented disparities in myocardial infarction survival by ], ], ], and census-tract-level ].<ref>{{cite journal | vauthors = Rosvall M, Gerward S, Engström G, Hedblad B | title = Income and short-term case fatality after myocardial infarction in the whole middle-aged population of Malmö, Sweden | journal = European Journal of Public Health | volume = 18 | issue = 5 | pages = 533–8 | date = October 2008 | pmid = 18621776 | doi = 10.1093/eurpub/ckn059 | doi-access = free }}</ref>
===Rehabilitation===
] aims to optimize function and ] in those afflicted with a heart disease. This can be with the help of a physician, or in the form of a cardiac rehabilitation program.<ref name=NHLBIrecovery>. U.S. ]. Retrieved December 2, 2006.</ref>


Race: In the U.S. ] have a greater burden of myocardial infarction and other cardiovascular events. On a population level, there is a higher overall ] of risk factors that are unrecognized and therefore not treated, which places these individuals at a greater likelihood of experiencing adverse outcomes and therefore potentially higher ] and ].<ref>{{cite journal | vauthors = Graham G | title = Disparities in cardiovascular disease risk in the United States | journal = Current Cardiology Reviews | volume = 11 | issue = 3 | pages = 238–45 | date = 2015-05-14 | pmid = 25418513 | pmc = 4558355 | doi = 10.2174/1573403X11666141122220003 }}</ref> Similarly, South Asians (including South Asians that have migrated to other countries around the world) experience higher rates of acute myocardial infarctions at younger ages, which can be largely explained by a higher prevalence of risk factors at younger ages.<ref>{{cite journal| last = Joshi | first = Prashant | date = 2007-01-17 | title = Risk Factors for Early Myocardial Infarction in South Asians Compared With Individuals in Other Countries | url = https://jamanetwork.com/journals/jama/article-abstract/205159 | access-date = 2023-11-16 | journal = JAMA | volume = 297 | issue = 3 | pages = 286–294 | doi = 10.1001/jama.297.3.286 | pmid = 17227980 }}</ref>
] is an important part of ] after a myocardial infarction, with beneficial effects on cholesterol levels, blood pressure, weight, ] and ].<ref name=NHLBIrecovery/> Some patients become afraid of exercising because it might trigger another infarct.<ref name=BBCrecovery>Trisha Macnair. . ], December 2005. Retrieved December 2, 2006.</ref> Patients are stimulated to exercise, and should only avoid certain exerting activities such as shovelling. Local authorities may place limitations on ] ].<ref name="NovaScotia-DrivingRegulations">{{cite web | title=Classification of Drivers' Licenses Regulations | publisher=Nova Scotia Registry of Regulations | date=May 24, 2000 | url=http://www.gov.ns.ca/just/regulations/regs/mvclasdl.htm | dateformat=mdy | accessdate=April 22 2007}}</ref> Some people are afraid to have ] after a heart attack. Most people can resume sexual activities after 3 to 4 weeks. The amount of activity needs to be dosed to the patient's possibilities.<ref name=familyphysician>"". ], updated March 2005. Retrieved December 4, 2006.</ref>


Socioeconomic status: Among individuals who live in the low-] (SES) areas, which is close to 25% of the US population, myocardial infarctions (MIs) occurred twice as often compared with people who lived in higher SES areas.<ref>{{cite journal | vauthors = Hamad R, Penko J, Kazi DS, Coxson P, Guzman D, Wei PC, Mason A, Wang EA, Goldman L, Fiscella K, Bibbins-Domingo K | display-authors = 6 | title = Association of Low Socioeconomic Status With Premature Coronary Heart Disease in US Adults | journal = JAMA Cardiology | volume = 5 | issue = 8 | pages = 899–908 | date = May 2020 | pmid = 32459344 | pmc = 7254448 | doi = 10.1001/jamacardio.2020.1458 }}</ref>
===Secondary prevention===
The risk of a recurrent myocardial infarction decreases with strict blood pressure management and lifestyle changes, chiefly ], regular ], a sensible ], and ].


Immigration status: In 2018 many lawfully present ]s who were eligible for coverage remained uninsured because immigrant families faced a range of enrollment barriers, including fear, confusion about eligibility policies, difficulty navigating the enrollment process, and ] and ] challenges. Uninsured ] are ineligible for coverage options due to their immigration status.<ref>{{cite web |date=2020-03-18|title=Health Coverage of Immigrants|url=https://www.kff.org/racial-equity-and-health-policy/fact-sheet/health-coverage-of-immigrants/|access-date=2021-04-09|website=KFF|language=en-US}}</ref>
Patients are usually commenced on several long-term medications post-MI, with the aim of preventing secondary cardiovascular events such as further myocardial infarctions, ] or ] (CVA). Unless contraindicated, such medications may include:<ref>Smith A, Aylward P, Campbell T, ''et al.'' Therapeutic Guidelines: Cardiovascular, 4th edition. North Melbourne: Therapeutic Guidelines; 2003. ISSN 1327-9513</ref><ref name=Rossi/>


Health care access: Lack of ] and financial concerns about accessing care were associated with delays in seeking emergency care for acute myocardial infarction which can have significant, adverse consequences on patient outcomes.<ref>{{cite journal | vauthors = Smolderen KG, Spertus JA, Nallamothu BK, Krumholz HM, Tang F, Ross JS, Ting HH, Alexander KP, Rathore SS, Chan PS | display-authors = 6 | title = Health care insurance, financial concerns in accessing care, and delays to hospital presentation in acute myocardial infarction | journal = JAMA | volume = 303 | issue = 14 | pages = 1392–400 | date = April 2010 | pmid = 20388895 | pmc = 3020978 | doi = 10.1001/jama.2010.409 }}</ref>
* ] therapy such as ] and/or ] should be continued to reduce the risk of plaque rupture and recurrent myocardial infarction. Aspirin is first-line, owing to its low cost and comparable efficacy, with clopidogrel reserved for patients intolerant of aspirin. The combination of clopidogrel and aspirin may further reduce risk of cardiovascular events, however the risk of ] is increased.<ref name="Peters-2003">{{cite journal | author=Peters RJ, Mehta SR, Fox KA, Zhao F, Lewis BS, Kopecky SL, Diaz R, Commerford PJ, Valentin V, Yusuf S; Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) Trial Investigators. | title=Effects of aspirin dose when used alone or in combination with clopidogrel in patients with acute coronary syndromes: observations from the Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) study | journal=Circulation | year=2003 | volume= 108 | issue=14 | pages=1682–7 | pmid=14504182 | doi = 10.1161/01.CIR.0000091201.39590.CB}}</ref>
* ] therapy such as ] or ] should be commenced.<ref name=Yusuf>{{cite journal |author=Yusuf S, Peto R, Lewis J, Collins R, Sleight P |title=Beta blockade during and after myocardial infarction: an overview of the randomized trials |journal=Prog Cardiovasc Dis |volume=27 |issue=5 |pages=335–71 |year=1985 |pmid=2858114 |doi= |url=}}</ref> These have been particularly beneficial in high-risk patients such as those with ] dysfunction and/or continuing cardiac ].<ref name="Dargie-2001">{{cite journal | author=Dargie HJ. | title=Effect of carvedilol on outcome after myocardial infarction in patients with left-ventricular dysfunction: the CAPRICORN randomised trial | journal=Lancet | year=2001 | volume=357 | issue=9266 | pages=1385–90 | pmid=11356434 | doi=10.1016/S0140-6736(00)04560-8}}</ref> β-Blockers decrease mortality and morbidity. They also improve symptoms of cardiac ischemia in NSTEMI.


Education: Researchers found that compared to people with ], those with lower educational attainment appeared to have a higher ] of heart attack, dying from a ] event, and overall death.<ref>{{cite journal | vauthors = Kelli HM, Mehta A, Tahhan AS, Liu C, Kim JH, Dong TA, Dhindsa DS, Ghazzal B, Choudhary MK, Sandesara PB, Hayek SS, Topel ML, Alkhoder AA, Martini MA, Sidoti A, Ko YA, Lewis TT, Vaccarino V, Sperling LS, Quyyumi AA | display-authors = 6 | title = Low Educational Attainment is a Predictor of Adverse Outcomes in Patients With Coronary Artery Disease | journal = Journal of the American Heart Association | volume = 8 | issue = 17 | pages = e013165 | date = September 2019 | pmid = 31476920 | pmc = 6755831 | doi = 10.1161/JAHA.119.013165 }}</ref>
* ] therapy should be commenced 24–48 hours post-MI in hemodynamically-stable patients, particularly in patients with a history of MI, ], ], ] location of infarct (as assessed by ECG), and/or evidence of left ventricular dysfunction. ACE inhibitors reduce mortality, the development of ], and decrease ventricular remodelling post-MI.<ref name="Pfeffer-1992">{{cite journal | author=Pfeffer MA, Braunwald E, Moye LA, Basta L, Brown EJ Jr, Cuddy TE, Davis BR, Geltman EM, Goldman S, Flaker GC, et al | title=Effect of captopril on mortality and morbidity in patients with left ventricular dysfunction after myocardial infarction. Results of the survival and ventricular enlargement trial. The SAVE Investigators | journal=N Engl J Med. | year= 1992 | volume= 327 | issue= 10 | pages= 669–77 | pmid=1386652}}</ref>


== Society and culture ==
* ] therapy has been shown to reduce mortality and morbidity post-MI.<ref name="Sacks-1996">{{cite journal | author=Sacks FM, Pfeffer MA, Moye LA, Rouleau JL, Rutherford JD, Cole TG, Brown L, Warnica JW, Arnold JM, Wun CC, Davis BR, Braunwald E. | title=The effect of pravastatin on coronary events after myocardial infarction in patients with average cholesterol levels. Cholesterol and Recurrent Events Trial investigators | journal=N Engl J Med | year=1996 | volume=335 | issue=14 | pages=1001–9 | pmid=8801446 | doi = 10.1056/NEJM199610033351401}}</ref><ref name="Sacks-1998">{{cite journal | author=Sacks FM, Moye LA, Davis BR, Cole TG, Rouleau JL, Nash DT, Pfeffer MA, Braunwald E. | title=Relationship between plasma LDL concentrations during treatment with pravastatin and recurrent coronary events in the Cholesterol and Recurrent Events trial | journal=Circulation | year=1998 | volume=97 | issue=15 | pages=1446–52 | pmid=9576424}}</ref> The effects of statins may be more than their LDL lowering effects. The general consensus is that statins have ] stabilization and multiple other ("pleiotropic") effects that may prevent myocardial infarction in addition to their effects on blood lipids.<ref name=Ray2005>{{cite journal |author=Ray KK, Cannon CP |title=The potential relevance of the multiple lipid-independent (pleiotropic) effects of statins in the management of acute coronary syndromes |journal=J. Am. Coll. Cardiol. |volume=46 |issue=8 |pages=1425–33 |year=2005 |pmid=16226165 |doi=10.1016/j.jacc.2005.05.086 |url=http://linkinghub.elsevier.com/retrieve/pii/S0735-1097(05)01773-0}}</ref>
Depictions of heart attacks in popular media often include collapsing or loss of consciousness which are not common symptoms; these depictions contribute to widespread misunderstanding about the symptoms of myocardial infarctions, which in turn contributes to people not getting care when they should.<ref>{{cite journal | vauthors = Perry K, Petrie KJ, Ellis CJ, Horne R, Moss-Morris R | title = Symptom expectations and delay in acute myocardial infarction patients | journal = Heart | volume = 86 | issue = 1 | pages = 91–3 | date = July 2001 | pmid = 11410572 | pmc = 1729795 | doi = 10.1136/heart.86.1.91 }}</ref>


=== Legal implications ===
* The ] agent ] has been shown to further reduce risk of cardiovascular death post-MI in patients with heart failure and left ventricular dysfunction, when used in conjunction with standard therapies above.<ref name=Pitt>{{cite journal | author = Keating G, Plosker G | title = Eplerenone: a review of its use in left ventricular systolic dysfunction and heart failure after acute myocardial infarction | journal = Drugs | volume = 64 | issue = 23 | pages = 2689–707 | year = 2004 | pmid = 15537370 | doi = 10.1157/13089615}}</ref>
At ], in general, a myocardial infarction is a ] but may sometimes be an ]. This can create coverage issues in the administration of no-fault insurance schemes such as ]. In general, a heart attack is not covered;<ref name=prairieview> {{webarchive|url=https://web.archive.org/web/20070711235600/http://www.pvamu.edu/pages/2026.asp |date=2007-07-11 }}. ]. Retrieved November 22, 2006.</ref> however, it may be a ] if it results, for example, from unusual emotional stress or unusual exertion.<ref name=biia> {{webarchive|url=https://web.archive.org/web/20061206115257/http://www.biia.wa.gov/SignificantDecisions/contents.htm |date=2006-12-06 }}. Board of Industrial Insurance Appeals. Retrieved November 22, 2006.</ref> In addition, in some jurisdictions, heart attacks had by persons in particular occupations such as ]s may be classified as line-of-duty injuries by statute or policy. In some countries or states, a person having had an MI may be prevented from participating in activity that puts other people's lives at risk, for example driving a car or flying an airplane.<ref name="NovaScotia-DrivingRegulations">{{cite web | title=Classification of Drivers' Licenses Regulations | publisher=Nova Scotia Registry of Regulations | date=May 24, 2000 | url=http://www.gov.ns.ca/just/regulations/regs/mvclasdl.htm | access-date=April 22, 2007 | url-status=live | archive-url=https://web.archive.org/web/20070420191108/http://www.gov.ns.ca/just/regulations/regs/mvclasdl.htm | archive-date=April 20, 2007 }}</ref>


== References ==
* ]s, commonly found in fish, have been shown to reduce mortality post-MI.<ref name="GISSI-Prevenzione-2001">{{cite journal | title=Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the ]-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico | journal=Lancet | year=2001 | volume=354 | issue=9177 | pages=447–55 | pmid=10465168 | doi=10.1016/S0140-6736(99)07072-5}}</ref> While the mechanism by which these fatty acids decrease mortality is unknown, it has been postulated that the survival benefit is due to electrical stabilization and the prevention of ].<ref name="Leaf-2005">{{cite journal | author = Leaf A, Albert C, Josephson M, Steinhaus D, Kluger J, Kang J, Cox B, Zhang H, Schoenfeld D | title = Prevention of fatal arrhythmias in high-risk subjects by fish oil n-3 fatty acid intake | journal = Circulation | volume = 112 | issue = 18 | pages = 2762–8 | year = 2005 | pmid = 16267249 | url = http://circ.ahajournals.org/cgi/content/full/112/18/2762 | doi = 10.1161/CIRCULATIONAHA.105.549527}}</ref> However, further studies in a high-risk subset have not shown a clear-cut decrease in potentially fatal arrhythmias due to omega-3 fatty acids.<ref name="Brouwer-2006">{{cite journal | author=Brouwer IA, Zock PL, Camm AJ, Bocker D, Hauer RN, Wever EF, Dullemeijer C, Ronden JE, Katan MB, Lubinski A, Buschler H, Schouten EG; SOFA Study Group. | title=Effect of fish oil on ventricular tachyarrhythmia and death in patients with implantable cardioverter defibrillators: the Study on Omega-3 Fatty Acids and Ventricular Arrhythmia (SOFA) randomized trial | journal=JAMA | year=2006 | volume=295 | issue=22 | pages=2613–9 | pmid=16772624 | doi = 10.1001/jama.295.22.2613}}</ref><ref name="Raitt-2005">{{cite journal | author=Raitt MH, Connor WE, Morris C, Kron J, Halperin B, Chugh SS, McClelland J, Cook J, MacMurdy K, Swenson R, Connor SL, Gerhard G, Kraemer DF, Oseran D, Marchant C, Calhoun D, Shnider R, McAnulty J. | title=Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial | journal=JAMA | year=2005 | volume=293 | issue=23 | pages=2284–91 | pmid=15956633 | doi = 10.1001/jama.293.23.2884}}</ref>
{{Reflist}}


===New therapies under investigation=== === Sources ===
{{refbegin}}
Patients who receive ] by ] injections of ] derived from their own ] after a myocardial infarction (MI) show improvements in left ventricular ] and ] not seen with ]. The larger the initial infarct size, the greater the effect of the infusion. ]s of ] infusion as a treatment approach to ST elevation MI are proceeding.<ref name=REPAIR2006>{{cite journal | author = Schachinger V, Erbs S, Elsasser A, Haberbosch W, Hambrecht R, Holschermann H, Yu J, Corti R, Mathey DG, Hamm CW, Suselbeck T, Assmus B, Tonn T, Dimmeler S, Zeiher AM; REPAIR-AMI Investigators | title = Intracoronary bone marrow-derived progenitor cells in acute myocardial infarction | year = 2006 | journal = N Engl J Med | volume = 355 | issue = 12 | pages = 1210–21 | pmid = 16990384 | doi = 10.1056/NEJMoa060186}}</ref>
* {{cite book| vauthors = Allison TG, Murphy JG |chapter=Stress Test Selection|pages=196–202| veditors = Murphy JG, Lloyd MA, Brady PA, Olsen LJ, Shields RC |title=Mayo Clinic Cardiology: Concise Textbook|url=https://books.google.com/books?id=WSCRAAAAQBAJ|date=6 December 2012|publisher=OUP US|isbn=978-0-19-991571-2}}
* {{cite book| vauthors = Blumenthal RS, Margolis S |title=Heart Attack Prevention 2007|url=https://books.google.com/books?id=mM3l59uTj04C&pg=PA10|year=2007|publisher=Johns Hopkins Health|isbn=978-1-933087-47-4}}
* {{cite book| vauthors = Dwight J |chapter=Chest pain, breathlessness, fatigue|pages=39–47| veditors = Warrell D, Cox T, Firth J, Dwight J |title=Oxford Textbook of Medicine: Cardiovascular Disorders|url=https://books.google.com/books?id=YqJHDAAAQBAJ|date=16 June 2016|publisher=Oxford University Press|isbn=978-0-19-871702-7}}
* {{cite book| vauthors = Gaziano TA, Gaziano JM |chapter= Global Evolving Epidemiology, Natural History, and Treatment Trends of Myocardial Infarction|pages= 11–21 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
* {{cite book| vauthors = Morrow DA, Bohula EA |chapter = Heart Failure and Cardiogenic Shock After Myocardial Infarction|pages=295–313 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
* {{cite book| vauthors = Morrow DA, Braunwald E |chapter = Classification and Diagnosis of Acute Coronary Syndromes|pages=1–10 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
* {{cite book| vauthors = Morrow DA |chapter=Clinical Approach to Suspected Acute Myocardial Infarction|pages= 55–65 | veditors = Morrow DA | title=Myocardial Infarction: A Companion to Braunwald's Heart Disease|url=https://books.google.com/books?id=0TzrjwEACAAJ|date=15 September 2016|publisher=Elsevier|isbn=978-0-323-35943-6}}
{{refend}}


== Further reading ==
There are currently 3 ] and ] approaches for the treatment of MI, but these are in an even earlier stage of ], so many questions and issues need to be addressed before they can be applied to patients. The first involves ]ic left ventricular restraints in the prevention of ]. The second utilizes '']'' engineered cardiac tissue, which is subsequently implanted '']''. The final approach entails injecting cells and/or a scaffold into the myocardium to create '']'' engineered cardiac tissue.<ref name=biomaterials2006>Christman KL, Lee RJ. "Biomaterials for the Treatment of Myocardial Infarction". ''J Am Coll Cardiol'' 2006; '''48'''(5): 907-13. PMID 16949479</ref>
{{refbegin}}
* {{cite journal | vauthors = Levine GN, Bates ER, Blankenship JC, Bailey SR, Bittl JA, Cercek B, Chambers CE, Ellis SG, Guyton RA, Hollenberg SM, Khot UN, Lange RA, Mauri L, Mehran R, Moussa ID, Mukherjee D, Ting HH, O'Gara PT, Kushner FG, Ascheim DD, Brindis RG, Casey DE, Chung MK, de Lemos JA, Diercks DB, Fang JC, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX | display-authors = 6 | title = 2015 ACC/AHA/SCAI Focused Update on Primary Percutaneous Coronary Intervention for Patients With ST-Elevation Myocardial Infarction: An Update of the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention and the 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Society for Cardiovascular Angiography and Interventions | journal = Circulation | volume = 133 | issue = 11 | pages = 1135–47 | date = March 2016 | pmid = 26490017 | doi = 10.1161/CIR.0000000000000336 | doi-access = free }}
* {{cite journal | vauthors=Min Cho S |display-authors=etal | year=2021 | title= Machine learning compared with conventional statistical models for predicting myocardial infarction readmission and mortality: a systematic review | journal=Canadian Journal of Cardiology | volume=37 | issue=8 | pages=1207–1214 | publisher=Elsevier | doi=10.1016/j.cjca.2021.02.020 | pmid=33677098 |doi-access=| s2cid=232141652 }}
{{refend}}


== External links ==
==Complications==
{{Medical condition classification and resources
Complications may occur immediately following the heart attack (in the ] phase), or may need time to develop (a ] problem). After an infarction, an obvious complication is a second infarction, which may occur in the domain of another atherosclerotic coronary artery, or in the same zone if there are any live cells left in the infarct.
| DiseasesDB = 8664
| ICD10 = {{ICD10|I|21||i|20}}-{{ICD10|I|22||i|20}}
| ICD9 = {{ICD9|410}}
| MedlinePlus = 000195
| eMedicineSubj = med
| eMedicineTopic = 1567
| eMedicine_mult = {{eMedicine2|emerg|327}} {{eMedicine2|ped|2520}}
| MeshID = D009203
}}
{{Sister project links|voy=no}}
* — Information and resources for preventing, recognizing, and treating a heart attack.
* TIMI Score for {{Webarchive|url=https://web.archive.org/web/20161105220551/http://www.mdcalc.com/timi-risk-score-for-uanstemi/ |date=2016-11-05 }} and {{Webarchive|url=https://web.archive.org/web/20090319073410/http://www.mdcalc.com/timi-risk-score-for-stemi |date=2009-03-19 }}
* {{Webarchive|url=https://web.archive.org/web/20161028004807/http://www.mdcalc.com/heart-score-for-major-cardiac-events/ |date=2016-10-28 }}
* {{cite web | url = https://medlineplus.gov/heartattack.html | publisher = U.S. National Library of Medicine | work = MedlinePlus | title = Heart Attack }}


{{Circulatory system pathology}}
===Congestive heart failure===
{{Hemodynamics}}
{{Main|Congestive heart failure}}
A myocardial infarction may compromise the function of the heart as a pump for the ], a state called ]. There are different types of heart failure; left- or right-sided (or bilateral) heart failure may occur depending on the affected part of the heart, and it is a low-output type of failure. If one of the heart valves is affected, this may cause dysfunction, such as ] in the case of left-sided coronary occlusion that disrupts the blood supply of the papillary muscles. The incidence of heart failure is particularly high in patients with diabetes and requires special management strategies.<ref name="Canto-2000">{{cite journal | author=Canto JG, Shlipak MG, Rogers WJ, Malmgren JA, Frederick PD, Lambrew CT, Ornato JP, Barron HV, Kiefe CI. | title=Prevalence, clinical characteristics, and mortality among patients with myocardial infarction presenting without chest pain | journal=JAMA | year=2000 | volume=283 | issue=24 | pages=3223–9 | pmid=10866870 | doi = 10.1001/jama.283.24.3223}}</ref>


{{Authority control}}
===Myocardial rupture===
{{Main|Myocardial rupture}}
] is most common three to five days after myocardial infarction, commonly of small degree, but may occur one day to three weeks later. In the modern era of early revascularization and intensive pharmacotherapy as treatment for MI, the incidence of myocardial rupture is about 1% of all MIs.<ref name="Yip-2003">{{cite journal | author=Yip HK, Wu CJ, Chang HW, Wang CP, Cheng CI, Chua S, Chen MC. | title=Cardiac rupture complicating acute myocardial infarction in the direct percutaneous coronary intervention reperfusion era | journal=Chest | year=2003 | volume=124 | issue=2 | pages=565–71 | format=] | url=http://www.chestjournal.org/cgi/reprint/124/2/565.pdf | pmid=12907544 | doi = 10.1378/chest.124.2.565}}</ref> This may occur in the free walls of the ], the ] between them, the ], or less commonly the ]. Rupture occurs because of increased pressure against the weakened walls of the heart chambers due to heart muscle that cannot pump blood out effectively. The weakness may also lead to ventricular ], a localized dilation or ballooning of the heart chamber.

Risk factors for myocardial rupture include completion of infarction (no revascularization performed), female sex, advanced age, and a lack of a previous history of myocardial infarction.<ref name="Yip-2003"/> In addition, the risk of rupture is higher in individuals who are revascularized with a thrombolytic agent than with PCI.<ref name="Becker-1996">{{cite journal | author=Becker RC, Gore JM, Lambrew C, Weaver WD, Rubison RM, French WJ, Tiefenbrunn AJ, Bowlby LJ, Rogers WJ. | title=A composite view of cardiac rupture in the United States National Registry of Myocardial Infarction | journal=J Am Coll Cardiol | year=1996 | volume=27 | issue=6 | pages=1321–6 | pmid=8626938 | doi = 10.1016/0735-1097(96)00008-3}}</ref><ref name="Moreno-2002">{{cite journal | author=Moreno R, Lopez-Sendon J, Garcia E, Perez de Isla L, Lopez de Sa E, Ortega A, Moreno M, Rubio R, Soriano J, Abeytua M, Garcia-Fernandez MA. | title=Primary angioplasty reduces the risk of left ventricular free wall rupture compared with thrombolysis in patients with acute myocardial infarction | journal=J Am Coll Cardiol | year=2002 | volume=39 | issue=4 | pages=598–603 | pmid=11849857 | doi = 10.1016/S0735-1097(01)01796-X}}</ref> The shear stress between the infarcted segment and the surrounding normal myocardium (which may be hypercontractile in the post-infarction period) makes it a nidus for rupture.<ref name="Shin-1983">{{cite journal | author=Shin P, Sakurai M, Minamino T, Onishi S, Kitamura H. | title=Postinfarction cardiac rupture. A pathogenetic consideration in eight cases | journal=Acta Pathol Jpn | year=1983 | volume=33 | issue=5 | pages=881–93 | pmid=6650169}}</ref>

Rupture is usually a catastrophic event that may result a life-threatening process known as ], in which blood accumulates within the ] or heart sac, and compresses the heart to the point where it cannot pump effectively. Rupture of the intraventricular septum (the muscle separating the left and right ventricles) causes a ] with ] of blood through the defect from the left side of the heart to the right side of the heart, which can lead to right ventricular failure as well as pulmonary overcirculation. Rupture of the papillary muscle may also lead to acute ] and subsequent ] and possibly even ].

===Life-threatening arrhythmia===
] showing ventricular tachycardia.]]
Since the electrical characteristics of the infarcted tissue change (see ]), ] are a frequent complication.<ref>{{cite book |title=Cardiac Arrhythmia: Mechanisms, Diagnosis, and Management |last=Podrid |first=Philip J. |coauthors=Peter R. Kowey |year=2001 |publisher=Lippincott Williams & Wilkins |isbn=0781724864 }}</ref> The re-entry phenomenon may cause rapid heart rates (] and even ]), and ischemia in the ] may cause a ] (when the impulse from the ], the normal cardiac pacemaker, does not reach the heart chambers).<ref>{{cite book |title=Fundamental Approaches to the Management of Cardiac Arrhythmias |last=Sung |first=Ruey J. |coauthors=Michael R. Lauer |year=2000 |publisher=Springer |isbn=0792365593 }}</ref><ref>{{cite book |title=Clinical Cardiac Electrophysiology: Techniques and Interpretations |last=Josephson |first=Mark E. |year=2002 |publisher=Lippincott Williams & Wilkins |isbn=0683306936 }}</ref>

===Pericarditis===
{{Main|Pericarditis}}
As a reaction to the damage of the heart muscle, ] cells are attracted. The inflammation may reach out and affect the heart sac. This is called ]. In ], this occurs several weeks after the initial event.

===Cardiogenic shock===
A complication that may occur in the acute setting soon after a myocardial infarction or in the weeks following it is ]. Cardiogenic shock is defined as a hemodynamic state in which the heart cannot produce enough of a ] to supply an adequate amount of oxygenated blood to the tissues of the body.

While the data on performing interventions on individuals with cardiogenic shock is sparse, trial data suggests a long-term mortality benefit in undergoing revascularization if the individual is less than 75 years old and if the onset of the acute myocardial infarction is less than 36 hours and the onset of cardiogenic shock is less than 18 hours.<ref name="Hochman-1999" /> If the patient with cardiogenic shock is not going to be revascularized, aggressive hemodynamic support is warranted, with insertion of an ] if not contraindicated.<ref name="Hochman-1999" /> If diagnostic coronary angiography does not reveal a culprit blockage that is the cause of the cardiogenic shock, the prognosis is poor.<ref name="Hochman-1999" />

==Prognosis==
The prognosis for patients with myocardial infarction varies greatly, depending on the patient, the condition itself and the given treatment. Using simple ]s which are immediately available in the ], patients with a higher risk of adverse outcome can be identified. For example, one study found that 0.4% of patients with a low risk profile had died after 90 days, whereas the ] in high risk patients was 21.1%.<ref name="PEPA">Lopez de Sa E, Lopez-Sendon J, Anguera I, Bethencourt A, Bosch X; Proyecto de Estudio del Pronostico de la Angina (PEPA) Investigators. "Prognostic value of clinical variables at presentation in patients with non-ST-segment elevation acute coronary syndromes: results of the Proyecto de Estudio del Pronostico de la Angina (PEPA)." ''Medicine (Baltimore)'' 2002; '''81'''(6): 434-42. PMID 12441900</ref>

Although studies differ in the identified variables, some of the more ] risk stratifiers include age, ] parameters (such as ], ] on admission, ] ], or ] of two or greater), ST-segment deviation, ], ] ] concentration, ] and elevation of cardiac markers.<ref name="PEPA"/><ref name="GRACE">Fox KA, Dabbous OH, Goldberg RJ, Pieper KS, Eagle KA, Van de Werf F, Avezum A, Goodman SG, Flather MD, Anderson FA Jr, Granger CB. "Prediction of risk of death and myocardial infarction in the six months after presentation with acute coronary syndrome: prospective multinational observational study (GRACE)." ''BMJ'' 2006; '''333'''(7578):1091. PMID 17032691</ref><ref name="Weir-2006">{{cite journal | author=Weir RA, McMurray JJ, Velazquez EJ. | title=Epidemiology of heart failure and left ventricular systolic dysfunction after acute myocardial infarction: prevalence, clinical characteristics, and prognostic importance | journal=Am J Cardiol | year=2006 | volume=97 | issue=10A | pages=13F–25F | pmid=16698331 | doi = 10.1016/j.amjcard.2006.03.005}}</ref>

Assessment of ] ] may increase the predictive power of some risk stratification models.<ref name="Bosch-2005">{{cite journal | author=Bosch X, Theroux P. | title=Left ventricular ejection fraction to predict early mortality in patients with non-ST-segment elevation acute coronary syndromes | journal=Am Heart J | year=2005 | volume=150 | issue=2 | pages=215–20 | pmid=16086920 | doi = 10.1016/j.ahj.2004.09.027}}</ref> The prognostic importance of Q-waves is debated.<ref>{{cite journal | author = Nicod P, Gilpin E, Dittrich H, Polikar R, Hjalmarson A, Blacky A, Henning H, Ross J | title = Short- and long-term clinical outcome after Q wave and non-Q wave myocardial infarction in a large patient population | journal = Circulation | volume = 79 | issue = 3 | pages = 528–36 | year = 1989 | pmid = 2645061}}</ref> Prognosis is significantly worsened if a mechanical complication (] rupture, myocardial free wall rupture, and so on) were to occur.<ref name="Becker-1996"/>

There is evidence that case fatality of myocardial infarction has been improving over the years in all ethnicities.<ref name="Liew-2006">{{cite journal | author=Liew R, Sulfi S, Ranjadayalan K, Cooper J, Timmis AD. | title=Declining case fatality rates for acute myocardial infarction in South Asian and white patients in the past 15 years | journal=Heart | year=2006 | volume=92 | issue=8 | pages=1030–4 | pmid=16387823 | doi = 10.1136/hrt.2005.078634}}</ref>

==Legal implications==
At ], a myocardial infarction is generally a ], but may sometimes be an ]. This has implications for no-fault insurance schemes such as ]. A heart attack is generally not covered;<ref name=prairieview>. ]. Retrieved November 22, 2006.</ref> however, it may be a ] if it results, for example, from unusual emotional stress or unusual exertion.<ref name=biia>. Board of Industrial Insurance Appeals. Retrieved November 22, 2006.</ref> Additionally, in some jurisdictions, heart attacks suffered by persons in particular occupations such as ]s may be classified as line-of-duty injuries by statute or policy. In some countries or states, a person who has suffered from a myocardial infarction may be prevented from participating in activity that puts other people's lives at risk, for example driving a car, taxi or airplane.<ref name="NovaScotia-DrivingRegulations"/>

==See also==
* ]
* ]
* ]
* ]
* ]
* ]
* ]

==References==
{{Reflist|2}}

==External links==
*
{{Sisterlinks}}
* based on data of the PROCAM study, provided by the International Task Force for Prevention of Coronary Heart Disease
* - based on information of the ], from the United States ]
* - overview of resources from ].
* - Information and resources for preventing, recognizing and treating heart attack.

{{Circulatory system pathology}}


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Latest revision as of 06:45, 5 January 2025

Interruption of cardiac blood supply "Heart attack" redirects here. For other uses, see Heart attack (disambiguation). Not to be confused with cardiac arrest, heart failure, or heart block.

Extensive area of old infarction, with fibrosis.

Medical condition
Myocardial infarction
Other namesAcute myocardial infarction (AMI), heart attack
A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, causing catastrophic thrombus formation, totally occluding the artery and preventing blood flow downstream to the heart muscle.
SpecialtyCardiology, emergency medicine
SymptomsChest pain, shortness of breath, nausea/vomiting, dizziness or lightheadedness, cold sweat, feeling tired; arm, neck, back, jaw, or stomach pain, decreased level or total loss of consciousness
ComplicationsHeart failure, irregular heartbeat, cardiogenic shock, coma, cardiac arrest
CausesAngina or coronary artery disease usually
Risk factorsHigh blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol
Diagnostic methodElectrocardiograms (ECGs), blood tests, coronary angiography
TreatmentPercutaneous coronary intervention, thrombolysis
MedicationAspirin, nitroglycerin, heparin
PrognosisSTEMI 10% risk of death (developed world)
Frequency15.9 million (2015)

A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom is retrosternal chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw. The pain may occasionally feel like heartburn. This is the dangerous type of Acute coronary syndrome.

Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat, feeling tired, and decreased level of consciousness. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest.

Most MIs occur due to coronary artery disease. Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, and excessive alcohol intake. The complete blockage of a coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mechanism of an MI. MIs are less commonly caused by coronary artery spasms, which may be due to cocaine, significant emotional stress (often known as Takotsubo syndrome or broken heart syndrome) and extreme cold, among others. Many tests are helpful with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography. An ECG, which is a recording of the heart's electrical activity, may confirm an ST elevation MI (STEMI), if ST elevation is present. Commonly used blood tests include troponin and less often creatine kinase MB.

Treatment of an MI is time-critical. Aspirin is an appropriate immediate treatment for a suspected MI. Nitroglycerin or opioids may be used to help with chest pain; however, they do not improve overall outcomes. Supplemental oxygen is recommended in those with low oxygen levels or shortness of breath. In a STEMI, treatments attempt to restore blood flow to the heart and include percutaneous coronary intervention (PCI), where the arteries are pushed open and may be stented, or thrombolysis, where the blockage is removed using medications. People who have a non-ST elevation myocardial infarction (NSTEMI) are often managed with the blood thinner heparin, with the additional use of PCI in those at high risk. In people with blockages of multiple coronary arteries and diabetes, coronary artery bypass surgery (CABG) may be recommended rather than angioplasty. After an MI, lifestyle modifications, along with long-term treatment with aspirin, beta blockers and statins, are typically recommended.

Worldwide, about 15.9 million myocardial infarctions occurred in 2015. More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI. STEMIs occur about twice as often in men as women. About one million people have an MI each year in the United States. In the developed world, the risk of death in those who have had a STEMI is about 10%. Rates of MI for a given age have decreased globally between 1990 and 2010. In 2011, an MI was one of the top five most expensive conditions during inpatient hospitalizations in the US, with a cost of about $11.5 billion for 612,000 hospital stays.

Terminology

Main article: Acute coronary syndrome

Myocardial infarction (MI) refers to tissue death (infarction) of the heart muscle (myocardium) caused by ischemia, the lack of oxygen delivery to myocardial tissue. It is a type of acute coronary syndrome, which describes a sudden or short-term change in symptoms related to blood flow to the heart. Unlike the other type of acute coronary syndrome, unstable angina, a myocardial infarction occurs when there is cell death, which can be estimated by measuring by a blood test for biomarkers (the cardiac protein troponin). When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ECG.

The phrase "heart attack" is often used non-specifically to refer to myocardial infarction. An MI is different from—but can cause—cardiac arrest, where the heart is not contracting at all or so poorly that all vital organs cease to function, thus leading to death. It is also distinct from heart failure, in which the pumping action of the heart is impaired. However, an MI may lead to heart failure.

Signs and symptoms

View of the chest with common areas of MI colouredView of the back with common areas of MI colouredAreas where pain is experienced in myocardial infarction, showing common (dark red) and less common (light red) areas on the chest (top) and back (bottom).

Chest pain that may or may not radiate to other parts of the body is the most typical and significant symptom of myocardial infarction. It might be accompanied by other symptoms such as sweating.

Pain

Chest pain is one of the most common symptoms of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper abdomen. The pain most suggestive of an acute MI, with the highest likelihood ratio, is pain radiating to the right arm and shoulder. Similarly, chest pain similar to a previous heart attack is also suggestive. The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes. It might be described as pressure, tightness, knifelike, tearing, burning sensation (all these are also manifested during other diseases). It could be felt as an unexplained anxiety, and pain might be absent altogether. Levine's sign, in which a person localizes the chest pain by clenching one or both fists over their sternum, has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value.

Typically, chest pain because of ischemia, be it unstable angina or myocardial infarction, lessens with the use of nitroglycerin, but nitroglycerin may also relieve chest pain arising from non-cardiac causes.

Other

Chest pain may be accompanied by sweating, nausea or vomiting, and fainting, and these symptoms may also occur without any pain at all. Dizziness or lightheadedness is common and occurs due to reduction in oxygen and blood to the brain. In females, the most common symptoms of myocardial infarction include shortness of breath, weakness, and fatigue. Females are more likely to have unusual or unexplained tiredness and nausea or vomiting as symptoms. Females having heart attacks are more likely to have palpitations, back pain, labored breath, vomiting, and left arm pain than males, although the studies showing these differences had high variability. Females are less likely to report chest pain during a heart attack and more likely to report nausea, jaw pain, neck pain, cough, and fatigue, although these findings are inconsistent across studies. Females with heart attacks also had more indigestion, dizziness, loss of appetite, and loss of consciousness. Shortness of breath is a common, and sometimes the only symptom, occurring when damage to the heart limits the output of the left ventricle, with breathlessness arising either from low oxygen in the blood or pulmonary edema.

Other less common symptoms include weakness, light-headedness, palpitations, and abnormalities in heart rate or blood pressure. These symptoms are likely induced by a massive surge of catecholamines from the sympathetic nervous system, which occurs in response to pain and, where present, low blood pressure. Loss of consciousness can occur in myocardial infarctions due to inadequate blood flow to the brain and cardiogenic shock, and sudden death, frequently due to the development of ventricular fibrillation. When the brain was without oxygen for too long due to a myocardial infarction, coma and persistent vegetative state can occur. Cardiac arrest, and atypical symptoms such as palpitations, occur more frequently in females, the elderly, those with diabetes, in people who have just had surgery, and in critically ill patients.

Absence

"Silent" myocardial infarctions can happen without any symptoms at all. These cases can be discovered later on electrocardiograms, using blood enzyme tests, or at autopsy after a person has died. Such silent myocardial infarctions represent between 22 and 64% of all infarctions, and are more common in the elderly, in those with diabetes mellitus and after heart transplantation. In people with diabetes, differences in pain threshold, autonomic neuropathy, and psychological factors have been cited as possible explanations for the lack of symptoms. In heart transplantation, the donor heart is not fully innervated by the nervous system of the recipient.

Risk factors

The most prominent risk factors for myocardial infarction are older age, actively smoking, high blood pressure, diabetes mellitus, and total cholesterol and high-density lipoprotein levels. Many risk factors of myocardial infarction are shared with coronary artery disease, the primary cause of myocardial infarction, with other risk factors including male sex, low levels of physical activity, a past family history, obesity, and alcohol use. Risk factors for myocardial disease are often included in risk factor stratification scores, such as the Framingham Risk Score. At any given age, men are more at risk than women for the development of cardiovascular disease. High levels of blood cholesterol is a known risk factor, particularly high low-density lipoprotein, low high-density lipoprotein, and high triglycerides.

Many risk factors for myocardial infarction are potentially modifiable, with the most important being tobacco smoking (including secondhand smoke). Smoking appears to be the cause of about 36% and obesity the cause of 20% of coronary artery disease. Lack of physical activity has been linked to 7–12% of cases. Less common causes include stress-related causes such as job stress, which accounts for about 3% of cases, and chronic high stress levels.

Diet

There is varying evidence about the importance of saturated fat in the development of myocardial infarctions. Eating polyunsaturated fat instead of saturated fats has been shown in studies to be associated with a decreased risk of myocardial infarction, while other studies find little evidence that reducing dietary saturated fat or increasing polyunsaturated fat intake affects heart attack risk. Dietary cholesterol does not appear to have a significant effect on blood cholesterol and thus recommendations about its consumption may not be needed. Trans fats do appear to increase risk. Acute and prolonged intake of high quantities of alcoholic drinks (3–4 or more daily) increases the risk of a heart attack.

Genetics

Family history of ischemic heart disease or MI, particularly if one has a male first-degree relative (father, brother) who had a myocardial infarction before age 55 years, or a female first-degree relative (mother, sister) less than age 65 increases a person's risk of MI.

Genome-wide association studies have found 27 genetic variants that are associated with an increased risk of myocardial infarction. The strongest association of MI has been found with chromosome 9 on the short arm p at locus 21, which contains genes CDKN2A and 2B, although the single nucleotide polymorphisms that are implicated are within a non-coding region. The majority of these variants are in regions that have not been previously implicated in coronary artery disease. The following genes have an association with MI: PCSK9, SORT1, MIA3, WDR12, MRAS, PHACTR1, LPA, TCF21, MTHFDSL, ZC3HC1, CDKN2A, 2B, ABO, PDGF0, APOA5, MNF1ASM283, COL4A1, HHIPC1, SMAD3, ADAMTS7, RAS1, SMG6, SNF8, LDLR, SLC5A3, MRPS6, KCNE2.

Other

See also: Overwork, Karoshi, and 996 working hour system

The risk of having a myocardial infarction increases with older age, low physical activity, and low socioeconomic status. Heart attacks appear to occur more commonly in the morning hours, especially between 6AM and noon. Evidence suggests that heart attacks are at least three times more likely to occur in the morning than in the late evening. Shift work is also associated with a higher risk of MI. One analysis has found an increase in heart attacks immediately following the start of daylight saving time.

Women who use combined oral contraceptive pills have a modestly increased risk of myocardial infarction, especially in the presence of other risk factors. The use of non-steroidal anti inflammatory drugs (NSAIDs), even for as short as a week, increases risk.

Endometriosis in women under the age of 40 is an identified risk factor.

Air pollution is also an important modifiable risk. Short-term exposure to air pollution such as carbon monoxide, nitrogen dioxide, and sulfur dioxide (but not ozone) has been associated with MI and other acute cardiovascular events. For sudden cardiac deaths, every increment of 30 units in Pollutant Standards Index correlated with an 8% increased risk of out-of-hospital cardiac arrest on the day of exposure. Extremes of temperature are also associated.

A number of acute and chronic infections including Chlamydophila pneumoniae, influenza, Helicobacter pylori, and Porphyromonas gingivalis among others have been linked to atherosclerosis and myocardial infarction. Myocardial infarction can also occur as a late consequence of Kawasaki disease.

Calcium deposits in the coronary arteries can be detected with CT scans. Calcium seen in coronary arteries can provide predictive information beyond that of classical risk factors. High blood levels of the amino acid homocysteine is associated with premature atherosclerosis; whether elevated homocysteine in the normal range is causal is controversial.

In people without evident coronary artery disease, possible causes for the myocardial infarction are coronary spasm or coronary artery dissection.

Mechanism

Atherosclerosis

Further information: Atherosclerosis
The animation shows plaque buildup or a coronary artery spasm can lead to a heart attack and how blocked blood flow in a coronary artery can lead to a heart attack.

The most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an artery supplying heart muscle. Plaques can become unstable, rupture, and additionally promote the formation of a blood clot that blocks the artery; this can occur in minutes. Blockage of an artery can lead to tissue death in tissue being supplied by that artery. Atherosclerotic plaques are often present for decades before they result in symptoms.

The gradual buildup of cholesterol and fibrous tissue in plaques in the wall of the coronary arteries or other arteries, typically over decades, is termed atherosclerosis. Atherosclerosis is characterized by progressive inflammation of the walls of the arteries. Inflammatory cells, particularly macrophages, move into affected arterial walls. Over time, they become laden with cholesterol products, particularly LDL, and become foam cells. A cholesterol core forms as foam cells die. In response to growth factors secreted by macrophages, smooth muscle and other cells move into the plaque and act to stabilize it. A stable plaque may have a thick fibrous cap with calcification. If there is ongoing inflammation, the cap may be thin or ulcerate. Exposed to the pressure associated with blood flow, plaques, especially those with a thin lining, may rupture and trigger the formation of a blood clot (thrombus). The cholesterol crystals have been associated with plaque rupture through mechanical injury and inflammation.

Other causes

Atherosclerotic disease is not the only cause of myocardial infarction, but it may exacerbate or contribute to other causes. A myocardial infarction may result from a heart with a limited blood supply subject to increased oxygen demands, such as in fever, a fast heart rate, hyperthyroidism, too few red blood cells in the bloodstream, or low blood pressure. Damage or failure of procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass grafts (CABG) may cause a myocardial infarction. Spasm of coronary arteries, such as Prinzmetal's angina may cause blockage.

Tissue death

Cross section showing anterior left ventricle wall infarction

If impaired blood flow to the heart lasts long enough, it triggers a process called the ischemic cascade; the heart cells in the territory of the blocked coronary artery die (infarction), chiefly through necrosis, and do not grow back. A collagen scar forms in their place. When an artery is blocked, cells lack oxygen, needed to produce ATP in mitochondria. ATP is required for the maintenance of electrolyte balance, particularly through the Na/K ATPase. This leads to an ischemic cascade of intracellular changes, necrosis and apoptosis of affected cells.

Cells in the area with the worst blood supply, just below the inner surface of the heart (endocardium), are most susceptible to damage. Ischemia first affects this region, the subendocardial region, and tissue begins to die within 15–30 minutes of loss of blood supply. The dead tissue is surrounded by a zone of potentially reversible ischemia that progresses to become a full-thickness transmural infarct. The initial "wave" of infarction can take place over 3–4 hours. These changes are seen on gross pathology and cannot be predicted by the presence or absence of Q waves on an ECG. The position, size and extent of an infarct depends on the affected artery, totality of the blockage, duration of the blockage, the presence of collateral blood vessels, oxygen demand, and success of interventional procedures.

Tissue death and myocardial scarring alter the normal conduction pathways of the heart and weaken affected areas. The size and location put a person at risk of abnormal heart rhythms (arrhythmias) or heart block, aneurysm of the heart ventricles, inflammation of the heart wall following infarction, and rupture of the heart wall that can have catastrophic consequences.

Injury to the myocardium also occurs during re-perfusion. This might manifest as ventricular arrhythmia. The re-perfusion injury is a consequence of the calcium and sodium uptake from the cardiac cells and the release of oxygen radicals during reperfusion. No-reflow phenomenon—when blood is still unable to be distributed to the affected myocardium despite clearing the occlusion—also contributes to myocardial injury. Topical endothelial swelling is one of many factors contributing to this phenomenon.

Diagnosis

Main article: Diagnosis of myocardial infarction

Criteria

Diagram showing the blood supply to the heart by the two major blood vessels, the left and right coronary arteries (labelled LCA and RCA). A myocardial infarction (2) has occurred with blockage of a branch of the left coronary artery (1).

A myocardial infarction, according to current consensus, is defined by elevated cardiac biomarkers with a rising or falling trend and at least one of the following:

Types

See also: Electrocardiography in myocardial infarction"STEMI" redirects here. For the Christian evangelist organization, see Stephen Tong § Ministry.

A myocardial infarction is usually clinically classified as an ST-elevation MI (STEMI) or a non-ST elevation MI (NSTEMI). These are based on ST elevation, a portion of a heartbeat graphically recorded on an ECG. STEMIs make up about 25–40% of myocardial infarctions. A more explicit classification system, based on international consensus in 2012, also exists. This classifies myocardial infarctions into five types:

  1. Spontaneous MI related to plaque erosion and/or rupture fissuring, or dissection
  2. MI related to ischemia, such as from increased oxygen demand or decreased supply, e.g., coronary artery spasm, coronary embolism, anemia, arrhythmias, high blood pressure, or low blood pressure
  3. Sudden unexpected cardiac death, including cardiac arrest, where symptoms may suggest MI, an ECG may be taken with suggestive changes, or a blood clot is found in a coronary artery by angiography and/or at autopsy, but where blood samples could not be obtained, or at a time before the appearance of cardiac biomarkers in the blood
  4. Associated with coronary angioplasty or stents
  5. Associated with CABG
  6. Associated with spontaneous coronary artery dissection in young, fit women

Cardiac biomarkers

There are many different biomarkers used to determine the presence of cardiac muscle damage. Troponins, measured through a blood test, are considered to be the best, and are preferred because they have greater sensitivity and specificity for measuring injury to the heart muscle than other tests. A rise in troponin occurs within 2–3 hours of injury to the heart muscle, and peaks within 1–2 days. The level of the troponin, as well as a change over time, are useful in measuring and diagnosing or excluding myocardial infarctions, and the diagnostic accuracy of troponin testing is improving over time. One high-sensitivity cardiac troponin can rule out a heart attack as long as the ECG is normal.

Other tests, such as CK-MB or myoglobin, are discouraged. CK-MB is not as specific as troponins for acute myocardial injury, and may be elevated with past cardiac surgery, inflammation or electrical cardioversion; it rises within 4–8 hours and returns to normal within 2–3 days. Copeptin may be useful to rule out MI rapidly when used along with troponin.

Electrocardiogram

A 12-lead ECG showing an inferior STEMI due to reduced perfusion through the right coronary artery. Elevation of the ST segment can be seen in leads II, III and aVF.

Electrocardiograms (ECGs) are a series of leads placed on a person's chest that measure electrical activity associated with contraction of the heart muscle. The taking of an ECG is an important part of the workup of an AMI, and ECGs are often not just taken once but may be repeated over minutes to hours, or in response to changes in signs or symptoms.

ECG readouts produce a waveform with different labeled features. In addition to a rise in biomarkers, a rise in the ST segment, changes in the shape or flipping of T waves, new Q waves, or a new left bundle branch block can be used to diagnose an AMI. In addition, ST elevation can be used to diagnose an ST segment myocardial infarction (STEMI). A rise must be new in V2 and V3 ≥2 mm (0,2 mV) for males or ≥1.5 mm (0.15 mV) for females or ≥1 mm (0.1 mV) in two other adjacent chest or limb leads. ST elevation is associated with infarction, and may be preceded by changes indicating ischemia, such as ST depression or inversion of the T waves. Abnormalities can help differentiate the location of an infarct, based on the leads that are affected by changes. Early STEMIs may be preceded by peaked T waves. Other ECG abnormalities relating to complications of acute myocardial infarctions may also be evident, such as atrial or ventricular fibrillation.

Imaging

ECG : AMI with ST elevation in V2-4

Noninvasive imaging plays an important role in the diagnosis and characterisation of myocardial infarction. Tests such as chest X-rays can be used to explore and exclude alternate causes of a person's symptoms. Echocardiography may assist in modifying clinical suspicion of ongoing myocardial infarction in patients that can't be ruled out or ruled in following initial ECG and Troponin testing. Myocardial perfusion imaging has no role in the acute diagnostic algorithm; however, it can confirm a clinical suspicion of Chronic Coronary Syndrome when the patient's history, physical examination (including cardiac examination) ECG, and cardiac biomarkers suggest coronary artery disease.

Echocardiography, an ultrasound scan of the heart, is able to visualize the heart, its size, shape, and any abnormal motion of the heart walls as they beat that may indicate a myocardial infarction. The flow of blood can be imaged, and contrast dyes may be given to improve image. Other scans using radioactive contrast include SPECT CT-scans using thallium, sestamibi (MIBI scans) or tetrofosmin; or a PET scan using Fludeoxyglucose or rubidium-82. These nuclear medicine scans can visualize the perfusion of heart muscle. SPECT may also be used to determine viability of tissue, and whether areas of ischemia are inducible.

Medical societies and professional guidelines recommend that the physician confirm a person is at high risk for Chronic Coronary Syndrome before conducting diagnostic non-invasive imaging tests to make a diagnosis, as such tests are unlikely to change management and result in increased costs. Patients who have a normal ECG and who are able to exercise, for example, most likely do not merit routine imaging.

  • Poor movement of the heart due to an MI as seen on ultrasound
  • Pulmonary edema due to an MI as seen on ultrasound

Differential diagnosis

There are many causes of chest pain, which can originate from the heart, lungs, gastrointestinal tract, aorta, and other muscles, bones and nerves surrounding the chest. In addition to myocardial infarction, other causes include angina, insufficient blood supply (ischemia) to the heart muscles without evidence of cell death, gastroesophageal reflux disease; pulmonary embolism, tumors of the lungs, pneumonia, rib fracture, costochondritis, heart failure and other musculoskeletal injuries. Rarer severe differential diagnoses include aortic dissection, esophageal rupture, tension pneumothorax, and pericardial effusion causing cardiac tamponade. The chest pain in an MI may mimic heartburn. Causes of sudden-onset breathlessness generally involve the lungs or heart – including pulmonary edema, pneumonia, allergic reactions and asthma, and pulmonary embolus, acute respiratory distress syndrome and metabolic acidosis. There are many different causes of fatigue, and myocardial infarction is not a common cause.

Prevention

There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarction, because of shared risk factors and an aim to reduce atherosclerosis affecting heart vessels. The influenza vaccine also appear to protect against myocardial infarction with a benefit of 15 to 45%.

Primary prevention

Lifestyle

Physical activity can reduce the risk of cardiovascular disease, and people at risk are advised to engage in 150 minutes of moderate or 75 minutes of vigorous intensity aerobic exercise a week. Keeping a healthy weight, drinking alcohol within the recommended limits, and quitting smoking reduce the risk of cardiovascular disease.

Substituting unsaturated fats such as olive oil and rapeseed oil instead of saturated fats may reduce the risk of myocardial infarction, although there is not universal agreement. Dietary modifications are recommended by some national authorities, with recommendations including increasing the intake of wholegrain starch, reducing sugar intake (particularly of refined sugar), consuming five portions of fruit and vegetables daily, consuming two or more portions of fish per week, and consuming 4–5 portions of unsalted nuts, seeds, or legumes per week. The dietary pattern with the greatest support is the Mediterranean diet. Vitamins and mineral supplements are of no proven benefit, and neither are plant stanols or sterols.

Public health measures may also act at a population level to reduce the risk of myocardial infarction, for example by reducing unhealthy diets (excessive salt, saturated fat, and trans-fat) including food labeling and marketing requirements as well as requirements for catering and restaurants and stimulating physical activity. This may be part of regional cardiovascular disease prevention programs or through the health impact assessment of regional and local plans and policies.

Most guidelines recommend combining different preventive strategies. A 2015 Cochrane Review found some evidence that such an approach might help with blood pressurebody mass index and waist circumference. However, there was insufficient evidence to show an effect on mortality or actual cardio-vascular events.

Medication

Statins, drugs that act to lower blood cholesterol, decrease the incidence and mortality rates of myocardial infarctions. They are often recommended in those at an elevated risk of cardiovascular diseases.

Aspirin has been studied extensively in people considered at increased risk of myocardial infarction. Based on numerous studies in different groups (e.g. people with or without diabetes), there does not appear to be a benefit strong enough to outweigh the risk of excessive bleeding. Nevertheless, many clinical practice guidelines continue to recommend aspirin for primary prevention, and some researchers feel that those with very high cardiovascular risk but low risk of bleeding should continue to receive aspirin.

Secondary prevention

There is a large crossover between the lifestyle and activity recommendations to prevent a myocardial infarction, and those that may be adopted as secondary prevention after an initial myocardial infarct. Recommendations include stopping smoking, a gradual return to exercise, eating a healthy diet, low in saturated fat and low in cholesterol, drinking alcohol within recommended limits, exercising, and trying to achieve a healthy weight. Exercise is both safe and effective even if people have had stents or heart failure, and is recommended to start gradually after 1–2 weeks. Counselling should be provided relating to medications used, and for warning signs of depression. Previous studies suggested a benefit from omega-3 fatty acid supplementation but this has not been confirmed.

Medications

Following a heart attack, nitrates, when taken for two days, and ACE-inhibitors decrease the risk of death. Other medications include:

Aspirin is continued indefinitely, as well as another antiplatelet agent such as clopidogrel or ticagrelor ("dual antiplatelet therapy" or DAPT) for up to twelve months. If someone has another medical condition that requires anticoagulation (e.g. with warfarin) this may need to be adjusted based on risk of further cardiac events as well as bleeding risk. In those who have had a stent, more than 12 months of clopidogrel plus aspirin does not affect the risk of death.

Beta blocker therapy such as metoprolol or carvedilol is recommended to be started within 24 hours, provided there is no acute heart failure or heart block. The dose should be increased to the highest tolerated. Contrary to most guidelines, the use of beta blockers does not appear to affect the risk of death, possibly because other treatments for MI have improved. When beta blocker medication is given within the first 24–72 hours of a STEMI no lives are saved. However, 1 in 200 people were prevented from a repeat heart attack, and another 1 in 200 from having an abnormal heart rhythm. Additionally, for 1 in 91 the medication causes a temporary decrease in the heart's ability to pump blood.

ACE inhibitor therapy should be started within 24 hours and continued indefinitely at the highest tolerated dose. This is provided there is no evidence of worsening kidney failure, high potassium, low blood pressure, or known narrowing of the renal arteries. Those who cannot tolerate ACE inhibitors may be treated with an angiotensin II receptor antagonist.

Statin therapy has been shown to reduce mortality and subsequent cardiac events and should be commenced to lower LDL cholesterol. Other medications, such as ezetimibe, may also be added with this goal in mind.

Aldosterone antagonists (spironolactone or eplerenone) may be used if there is evidence of left ventricular dysfunction after an MI, ideally after beginning treatment with an ACE inhibitor.

Other

A defibrillator, an electric device connected to the heart and surgically inserted under the skin, may be recommended. This is particularly if there are any ongoing signs of heart failure, with a low left ventricular ejection fraction and a New York Heart Association grade II or III after 40 days of the infarction. Defibrillators detect potentially fatal arrhythmia and deliver an electrical shock to the person to depolarize a critical mass of the heart muscle.

First aid

Further information: Management of acute coronary syndrome § Patient-dependent initial measures

Taking aspirin helps to reduce the risk of mortality in people with myocardial infarction.

Management

Main article: Management of acute coronary syndrome

A myocardial infarction requires immediate medical attention. Treatment aims to preserve as much heart muscle as possible, and to prevent further complications. Treatment depends on whether the myocardial infarction is a STEMI or NSTEMI. Treatment in general aims to unblock blood vessels, reduce blood clot enlargement, reduce ischemia, and modify risk factors with the aim of preventing future MIs. In addition, the main treatment for myocardial infarctions with ECG evidence of ST elevation (STEMI) include thrombolysis or percutaneous coronary intervention, although PCI is also ideally conducted within 1–3 days for NSTEMI. In addition to clinical judgement, risk stratification may be used to guide treatment, such as with the TIMI and GRACE scoring systems.

Pain

The pain associated with myocardial infarction is often treated with nitroglycerin, a vasodilator, or opioid medications such as morphine. Nitroglycerin (given under the tongue or injected into a vein) may improve blood supply to the heart. It is an important part of therapy for its pain relief effects, though there is no proven benefit to mortality. Morphine or other opioid medications may also be used, and are effective for the pain associated with STEMI. There is poor evidence that morphine shows any benefit to overall outcomes, and there is some evidence of potential harm.

Antithrombotics

Aspirin, an antiplatelet drug, is given as a loading dose to reduce the clot size and reduce further clotting in the affected artery. It is known to decrease mortality associated with acute myocardial infarction by at least 50%. P2Y12 inhibitors such as clopidogrel, prasugrel and ticagrelor are given concurrently, also as a loading dose, with the dose depending on whether further surgical management or fibrinolysis is planned. Prasugrel and ticagrelor are recommended in European and American guidelines, as they are active more quickly and consistently than clopidogrel. P2Y12 inhibitors are recommended in both NSTEMI and STEMI, including in PCI, with evidence also to suggest improved mortality. Heparins, particularly in the unfractionated form, act at several points in the clotting cascade, help to prevent the enlargement of a clot, and are also given in myocardial infarction, owing to evidence suggesting improved mortality rates. In very high-risk scenarios, inhibitors of the platelet glycoprotein αIIbβ3a receptor such as eptifibatide or tirofiban may be used.

There is varying evidence on the mortality benefits in NSTEMI. A 2014 review of P2Y12 inhibitors such as clopidogrel found they do not change the risk of death when given to people with a suspected NSTEMI prior to PCI, nor do heparins change the risk of death. They do decrease the risk of having a further myocardial infarction.

Angiogram

Inserting a stent to widen the artery.

Primary percutaneous coronary intervention (PCI) is the treatment of choice for STEMI if it can be performed in a timely manner, ideally within 90–120 minutes of contact with a medical provider. Some recommend it is also done in NSTEMI within 1–3 days, particularly when considered high-risk. A 2017 review, however, did not find a difference between early versus later PCI in NSTEMI.

PCI involves small probes, inserted through peripheral blood vessels such as the femoral artery or radial artery into the blood vessels of the heart. The probes are then used to identify and clear blockages using small balloons, which are dragged through the blocked segment, dragging away the clot, or the insertion of stents. Coronary artery bypass grafting is only considered when the affected area of heart muscle is large, and PCI is unsuitable, for example with difficult cardiac anatomy. After PCI, people are generally placed on aspirin indefinitely and on dual antiplatelet therapy (generally aspirin and clopidogrel) for at least a year.

Fibrinolysis

Main article: Thrombolysis

If PCI cannot be performed within 90 to 120 minutes in STEMI then fibrinolysis, preferably within 30 minutes of arrival to hospital, is recommended. If a person has had symptoms for 12 to 24 hours evidence for effectiveness of thrombolysis is less and if they have had symptoms for more than 24 hours it is not recommended. Thrombolysis involves the administration of medication that activates the enzymes that normally dissolve blood clots. These medications include tissue plasminogen activator, reteplase, streptokinase, and tenecteplase. Thrombolysis is not recommended in a number of situations, particularly when associated with a high risk of bleeding or the potential for problematic bleeding, such as active bleeding, past strokes or bleeds into the brain, or severe hypertension. Situations in which thrombolysis may be considered, but with caution, include recent surgery, use of anticoagulants, pregnancy, and proclivity to bleeding. Major risks of thrombolysis are major bleeding and intracranial bleeding. Pre-hospital thrombolysis reduces time to thrombolytic treatment, based on studies conducted in higher income countries; however, it is unclear whether this has an impact on mortality rates.

Other

In the past, high flow oxygen was recommended for everyone with a possible myocardial infarction. More recently, no evidence was found for routine use in those with normal oxygen levels and there is potential harm from the intervention. Therefore, oxygen is currently only recommended if oxygen levels are found to be low or if someone is in respiratory distress.

If despite thrombolysis there is significant cardiogenic shock, continued severe chest pain, or less than a 50% improvement in ST elevation on the ECG recording after 90 minutes, then rescue PCI is indicated emergently.

Those who have had cardiac arrest may benefit from targeted temperature management with evaluation for implementation of hypothermia protocols. Furthermore, those with cardiac arrest, and ST elevation at any time, should usually have angiography. Aldosterone antagonists appear to be useful in people who have had an STEMI and do not have heart failure.

Rehabilitation and exercise

Cardiac rehabilitation benefits many who have experienced myocardial infarction, even if there has been substantial heart damage and resultant left ventricular failure. It should start soon after discharge from the hospital. The program may include lifestyle advice, exercise, social support, as well as recommendations about driving, flying, sports participation, stress management, and sexual intercourse. Returning to sexual activity after myocardial infarction is a major concern for most patients, and is an important area to be discussed in the provision of holistic care.

In the short-term, exercise-based cardiovascular rehabilitation programs may reduce the risk of a myocardial infarction, reduces a large number of hospitalizations from all causes, reduces hospital costs, improves health-related quality of life, and has a small effect on all-cause mortality. Longer-term studies indicate that exercise-based cardiovascular rehabilitation programs may reduce cardiovascular mortality and myocardial infarction.

Prognosis

The prognosis after myocardial infarction varies greatly depending on the extent and location of the affected heart muscle, and the development and management of complications. Prognosis is worse with older age and social isolation. Anterior infarcts, persistent ventricular tachycardia or fibrillation, development of heart blocks, and left ventricular impairment are all associated with poorer prognosis. Without treatment, about a quarter of those affected by MI die within minutes and about forty percent within the first month. Morbidity and mortality from myocardial infarction has, however, improved over the years due to earlier and better treatment: in those who have a STEMI in the United States, between 5 and 6 percent die before leaving the hospital and 7 to 18 percent die within a year.

It is unusual for babies to experience a myocardial infarction, but when they do, about half die. In the short-term, neonatal survivors seem to have a normal quality of life.

Complications

Main article: Myocardial infarction complications

Complications may occur immediately following the myocardial infarction or may take time to develop. Disturbances of heart rhythms, including atrial fibrillation, ventricular tachycardia and fibrillation and heart block can arise as a result of ischemia, cardiac scarring, and infarct location. Stroke is also a risk, either as a result of clots transmitted from the heart during PCI, as a result of bleeding following anticoagulation, or as a result of disturbances in the heart's ability to pump effectively as a result of the infarction. Regurgitation of blood through the mitral valve is possible, particularly if the infarction causes dysfunction of the papillary muscle. Cardiogenic shock as a result of the heart being unable to adequately pump blood may develop, dependent on infarct size, and is most likely to occur within the days following an acute myocardial infarction. Cardiogenic shock is the largest cause of in-hospital mortality. Rupture of the ventricular dividing wall or left ventricular wall may occur within the initial weeks. Dressler's syndrome, a reaction following larger infarcts and a cause of pericarditis is also possible.

Heart failure may develop as a long-term consequence, with an impaired ability of heart muscle to pump, scarring, and an increase in the size of the existing muscle. Aneurysm of the left ventricle myocardium develops in about 10% of MI and is itself a risk factor for heart failure, ventricular arrhythmia, and the development of clots.

Risk factors for complications and death include age, hemodynamic parameters (such as heart failure, cardiac arrest on admission, systolic blood pressure, or Killip class of two or greater), ST-segment deviation, diabetes, serum creatinine, peripheral vascular disease, and elevation of cardiac markers.

Epidemiology

Myocardial infarction is a common presentation of coronary artery disease. The World Health Organization estimated in 2004, that 12.2% of worldwide deaths were from ischemic heart disease; with it being the leading cause of death in high- or middle-income countries and second only to lower respiratory infections in lower-income countries. Worldwide, more than 3 million people have STEMIs and 4 million have NSTEMIs a year. STEMIs occur about twice as often in men as women.

Rates of death from ischemic heart disease (IHD) have slowed or declined in most high-income countries, although cardiovascular disease still accounted for one in three of all deaths in the US in 2008. For example, rates of death from cardiovascular disease have decreased almost a third between 2001 and 2011 in the United States.

In contrast, IHD is becoming a more common cause of death in the developing world. For example, in India, IHD had become the leading cause of death by 2004, accounting for 1.46 million deaths (14% of total deaths) and deaths due to IHD were expected to double during 1985–2015. Globally, disability adjusted life years (DALYs) lost to ischemic heart disease are predicted to account for 5.5% of total DALYs in 2030, making it the second-most-important cause of disability (after unipolar depressive disorder), as well as the leading cause of death by this date.

Social determinants of health

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Social determinants such as neighborhood disadvantage, immigration status, lack of social support, social isolation, and access to health services play an important role in myocardial infarction risk and survival. Studies have shown that low socioeconomic status is associated with an increased risk of poorer survival. There are well-documented disparities in myocardial infarction survival by socioeconomic status, race, education, and census-tract-level poverty.

Race: In the U.S. African Americans have a greater burden of myocardial infarction and other cardiovascular events. On a population level, there is a higher overall prevalence of risk factors that are unrecognized and therefore not treated, which places these individuals at a greater likelihood of experiencing adverse outcomes and therefore potentially higher morbidity and mortality. Similarly, South Asians (including South Asians that have migrated to other countries around the world) experience higher rates of acute myocardial infarctions at younger ages, which can be largely explained by a higher prevalence of risk factors at younger ages.

Socioeconomic status: Among individuals who live in the low-socioeconomic (SES) areas, which is close to 25% of the US population, myocardial infarctions (MIs) occurred twice as often compared with people who lived in higher SES areas.

Immigration status: In 2018 many lawfully present immigrants who were eligible for coverage remained uninsured because immigrant families faced a range of enrollment barriers, including fear, confusion about eligibility policies, difficulty navigating the enrollment process, and language and literacy challenges. Uninsured undocumented immigrants are ineligible for coverage options due to their immigration status.

Health care access: Lack of health insurance and financial concerns about accessing care were associated with delays in seeking emergency care for acute myocardial infarction which can have significant, adverse consequences on patient outcomes.

Education: Researchers found that compared to people with graduate degrees, those with lower educational attainment appeared to have a higher risk of heart attack, dying from a cardiovascular event, and overall death.

Society and culture

Depictions of heart attacks in popular media often include collapsing or loss of consciousness which are not common symptoms; these depictions contribute to widespread misunderstanding about the symptoms of myocardial infarctions, which in turn contributes to people not getting care when they should.

Legal implications

At common law, in general, a myocardial infarction is a disease but may sometimes be an injury. This can create coverage issues in the administration of no-fault insurance schemes such as workers' compensation. In general, a heart attack is not covered; however, it may be a work-related injury if it results, for example, from unusual emotional stress or unusual exertion. In addition, in some jurisdictions, heart attacks had by persons in particular occupations such as police officers may be classified as line-of-duty injuries by statute or policy. In some countries or states, a person having had an MI may be prevented from participating in activity that puts other people's lives at risk, for example driving a car or flying an airplane.

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ClassificationD
External resources
Cardiovascular disease (heart)
Ischemia
Coronary disease
Active ischemia
Sequelae
Layers
Pericardium
Myocardium
Endocardium /
valves
Endocarditis
Valves
Conduction /
arrhythmia
Bradycardia
Tachycardia
(paroxysmal and sinus)
Supraventricular
Ventricular
Premature contraction
Pre-excitation syndrome
Flutter / fibrillation
Pacemaker
Long QT syndrome
Cardiac arrest
Other / ungrouped
Cardiomegaly
Other
Ischaemia and infarction
Ischemia
Infarction
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Myocardial infarction: Difference between revisions Add topic