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Myocardial infarction

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, feeling faint, cold sweat, feeling tired; arm, neck, back, jaw, or stomach pain,[1][2] loss of consciousness
ComplicationsHeart failure, irregular heartbeat, cardiogenic shock, cardiac arrest[3][4]
CausesUsually coronary artery disease[3]
Risk factorsHigh blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol[5][6]
Diagnostic methodElectrocardiograms (ECGs), blood tests, coronary angiography[7]
TreatmentPercutaneous coronary intervention, thrombolysis[8]
MedicationAspirin, nitroglycerin, heparin[8][9]
PrognosisSTEMI 10% risk of death (developed world)[8]
Frequency15.9 million (2015)[10]

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 damage to the heart muscle.[1] The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw.[1] Often it occurs in the center or left side of the chest and lasts for more than a few minutes.[1] The discomfort may occasionally feel like heartburn.[1] Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat or feeling tired.[1] About 30% of people have atypical symptoms.[8] Women more often present without chest pain and instead have neck pain, arm pain or feel tired.[11] Among those over 75 years old, about 5% have had an MI with little or no history of symptoms.[12] An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest.[3][4]

Most MIs occur due to coronary artery disease.[3] Risk factors include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet and excessive alcohol intake.[5][6] The complete blockage of a coronary artery caused by a rupture of an atherosclerotic plaque is usually the underlying mechanism of an MI.[3] MIs are less commonly caused by coronary artery spasms, which may be due to cocaine, significant emotional stress (commonly known as Takotsubo syndrome or broken heart syndrome) and extreme cold, among others.[13][14] A number of tests are useful to help with diagnosis, including electrocardiograms (ECGs), blood tests and coronary angiography.[7] An ECG, which is a recording of the heart's electrical activity, may confirm an ST elevation MI (STEMI), if ST elevation is present.[8][15] Commonly used blood tests include troponin and less often creatine kinase MB.[7]

Treatment of an MI is time-critical.[16] Aspirin is an appropriate immediate treatment for a suspected MI.[9] Nitroglycerin or opioids may be used to help with chest pain; however, they do not improve overall outcomes.[8][9] Supplemental oxygen is recommended in those with low oxygen levels or shortness of breath.[9] 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.[8] 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.[9] In people with blockages of multiple coronary arteries and diabetes, coronary artery bypass surgery (CABG) may be recommended rather than angioplasty.[17] After an MI, lifestyle modifications, along with long-term treatment with aspirin, beta blockers and statins, are typically recommended.[8]

Worldwide, about 15.9 million myocardial infarctions occurred in 2015.[10] More than 3 million people had an ST elevation MI, and more than 4 million had an NSTEMI.[18] STEMIs occur about twice as often in men as women.[19] About one million people have an MI each year in the United States.[3] In the developed world, the risk of death in those who have had an STEMI is about 10%.[8] Rates of MI for a given age have decreased globally between 1990 and 2010.[20] 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.[21]

  1. ^ a b c d e f "What Are the Signs and Symptoms of Coronary Heart Disease?". www.nhlbi.nih.gov. September 29, 2014. Archived from the original on 24 February 2015. Retrieved 23 February 2015.
  2. ^ "Heart Attack Symptoms in Women". American Heart Association.
  3. ^ a b c d e f "What Is a Heart Attack?". www.nhlbi.nih.gov. December 17, 2013. Archived from the original on 19 February 2015. Retrieved 24 February 2015.
  4. ^ a b "Heart Attack or Sudden Cardiac Arrest: How Are They Different?". www.heart.org. Jul 30, 2014. Archived from the original on 24 February 2015. Retrieved 24 February 2015.
  5. ^ a b Mehta PK, Wei J, Wenger NK (February 2015). "Ischemic heart disease in women: a focus on risk factors". Trends in Cardiovascular Medicine. 25 (2): 140–51. doi:10.1016/j.tcm.2014.10.005. PMC 4336825. PMID 25453985.
  6. ^ a b Mendis S, Puska P, Norrving B (2011). Global atlas on cardiovascular disease prevention and control (PDF) (1st ed.). Geneva: World Health Organization in collaboration with the World Heart Federation and the World Stroke Organization. pp. 3–18. ISBN 978-92-4-156437-3. Archived (PDF) from the original on 2014-08-17.
  7. ^ a b c "How Is a Heart Attack Diagnosed?". www.nhlbi.nih.gov. December 17, 2013. Archived from the original on 24 February 2015. Retrieved 24 February 2015.
  8. ^ a b c d e f g h i Steg PG, James SK, Atar D, Badano LP, Blömstrom-Lundqvist C, Borger MA, et al. (October 2012). "ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation". European Heart Journal. 33 (20): 2569–619. doi:10.1093/eurheartj/ehs215. PMID 22922416.
  9. ^ a b c d e O'Connor RE, Brady W, Brooks SC, Diercks D, Egan J, Ghaemmaghami C, et al. (November 2010). "Part 10: acute coronary syndromes: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care". Circulation. 122 (18 Suppl 3): S787–817. doi:10.1161/CIRCULATIONAHA.110.971028. PMID 20956226.
  10. ^ a b Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, et al. (GBD 2015 Disease Injury Incidence Prevalence Collaborators) (October 2016). "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". Lancet. 388 (10053): 1545–1602. doi:10.1016/S0140-6736(16)31678-6. PMC 5055577. PMID 27733282.
  11. ^ Coventry LL, Finn J, Bremner AP (2011). "Sex differences in symptom presentation in acute myocardial infarction: a systematic review and meta-analysis". Heart & Lung. 40 (6): 477–91. doi:10.1016/j.hrtlng.2011.05.001. PMID 22000678.
  12. ^ Valensi P, Lorgis L, Cottin Y (March 2011). "Prevalence, incidence, predictive factors and prognosis of silent myocardial infarction: a review of the literature". Archives of Cardiovascular Diseases. 104 (3): 178–88. doi:10.1016/j.acvd.2010.11.013. PMID 21497307.
  13. ^ "What Causes a Heart Attack?". www.nhlbi.nih.gov. December 17, 2013. Archived from the original on 18 February 2015. Retrieved 24 February 2015.
  14. ^ Devlin RJ, Henry JA (2008). "Clinical review: Major consequences of illicit drug consumption". Critical Care. 12 (1): 202. doi:10.1186/cc6166. PMC 2374627. PMID 18279535.
  15. ^ "Electrocardiogram". NHLBI, NIH. 9 December 2016. Archived from the original on 11 April 2017. Retrieved 10 April 2017.
  16. ^ Colledge NR, Walker BR, Ralston SH, Davidson LS (2010). Davidson's principles and practice of medicine (21st ed.). Edinburgh: Churchill Livingstone/Elsevier. pp. 588–599. ISBN 978-0-7020-3085-7.
  17. ^ Hamm CW, Bassand JP, Agewall S, Bax J, Boersma E, Bueno H, et al. (December 2011). "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)". European Heart Journal. 32 (23): 2999–3054. doi:10.1093/eurheartj/ehr236. PMID 21873419.
  18. ^ White HD, Chew DP (August 2008). "Acute myocardial infarction". Lancet. 372 (9638): 570–84. doi:10.1016/S0140-6736(08)61237-4. PMC 1931354. PMID 18707987.
  19. ^ O'Gara PT, Kushner FG, Ascheim DD, Casey DE, Chung MK, de Lemos JA, et al. (January 2013). "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". Circulation. 127 (4): e362–425. doi:10.1161/CIR.0b013e3182742cf6. PMID 23247304.
  20. ^ Moran AE, Forouzanfar MH, Roth GA, Mensah GA, Ezzati M, Flaxman A, et al. (April 2014). "The global burden of ischemic heart disease in 1990 and 2010: the Global Burden of Disease 2010 study". Circulation. 129 (14): 1493–501. doi:10.1161/circulationaha.113.004046. PMC 4181601. PMID 24573351.
  21. ^ Torio C (August 2013). "National Inpatient Hospital Costs: The Most Expensive Conditions by Payer, 2011". HCUP. Archived from the original on 14 March 2017. Retrieved 1 May 2017.

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