What are the types of myocardial infarction (MI, heart attack), and how is each defined?

Updated: May 07, 2019
  • Author: A Maziar Zafari, MD, PhD, FACC, FAHA; Chief Editor: Eric H Yang, MD  more...
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Answer

The Joint ESC/ACCF/AHA/WHF Task Force further classified MI into 5 types on the basis of the underlying cause [7] :

  • Type 1 (spontaneous MI): Related to atherosclerotic plaque rupture, ulceration, fissuring, erosion, or dissection with intraluminal thrombus in one or more of the coronary arteries, leading to decreased myocardial blood flow or distal platelet emboli and thereby resulting in myocyte necrosis. The patient may or may not have underlying obstructive coronary artery disease (CAD).
  • Type 2 (MI secondary to an ischemic imbalance): MI consequent to increased oxygen demand or a decreased supply (eg, coronary endothelial dysfunction, coronary artery spasm, coronary artery embolus, tachyarryhthmias/bradyarrhythmias, anemia, respiratory failure, hypertension, or hypotension).
  • Type 3 (MI resulting in death when biomarker values are unavailable): Sudden, unexpected cardiac death before blood samples for biomarkers could be drawn or before their appearance in the circulation.
  • Type 4a (MI related to percutaneous coronary intervention [PCI]): Elevation of biomarker values (cTn is preferred) to more than 5 times the 99 th percentile of the URL in patients with normal baseline values (<99<sup>th</sup> percentile URL) or a rise of values over 20% if the baseline values are elevated but stable or falling. In addition, any of the following are required: (1) symptoms suggestive of myocardial ischemia; (2) new ischemic ECG changes or new BBB; (3) angiographic loss of patency of a major coronary artery or a side branch or persistent slow flow or no flow or embolization; or (4) demonstration of  the new loss of viable myocardium or new regional wall motion abnormality by cardiac imaging.
  • Type 4b (MI related to stent thrombosis): MI associated with stent thrombosis as detected by coronary angiography or autopsy in the setting of myocardial ischemia in combination with a rise and/or fall of cardiac biomarkers with at least one value above the 99 th percentile URL.
  • Type 5 (MI related to coronary artery bypass grafting [CABG]): Elevation of cardiac biomarker values more than 10 times the 99 th percentile URL in patients with normal baseline cTn values. In addition, either (1) new pathologic Q waves or new BBB, (2) angiographic-documented new graft or native coronary artery occlusion, or (3) evidence of new loss of viable myocardium or new regional wall motion abnormality by cardiac imaging is required.

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