Defining Acute MI

Defining Acute MI

Definition

• In 1979: The diagnosis of acute MI was based on WHO criteria based on epidemiology
• In 2000: Joint European Society of Cardiology (ESC) andAmerican College of Cardiology (ACC) committee proposed a clinically based definition of an acute, evolving, or recent MI.
• In 2007: Joint Task Force of the European Society of Cardiology, American College of Cardiology Foundation, the American Heart Association, and the World Health Federation  (ESC/ACCF/AHA/WHF) refined the 2000 criteria and defined acute MI as a clinical event consequent to the death of cardiac myocytes (myocardial necrosis) that is caused by ischemia (as opposed to other etiologies such as myocarditis or trauma)
• 2012: This definition was not fundamentally changed in the third universal definition of MI released in 2012 by the ESC/ACCF/AHA/WHF.

Third universal definition
Any one of the following criteria meets the diagnosis of MI:
1.    Detection of a rise and/or fall of cardiac biomarker values (cTn with at least one value above the 99^th percentile upper reference limit [URL]) and with at least one of the following:
a.     Symptoms of ischemia
b.    Development of pathologic Q waves in the ECG
c. New or presumed new significant ST-segment-T wave (ST-T) changes
d. New LBBB
e. Identification of an intracoronary thrombus by angiography or autopsy
f. Imaging evidence of new loss of viable myocardium or a new regional wall motion abnormality.
2.    Cardiac death with symptoms suggestive of myocardial ischemia and presumed new ischemia ECG changes or new LBBB, but death occurred before cardiac biomarkers were obtained, or before cardiac biomarker values would be increased.

3. PCI related MI: elevation of cTn >5 x 99^th percentile upper reference limit in patients with normal baseline values or a rise of values >20 percent if the baseline values are elevated and are stable or falling. In addition, either (i) symptoms suggestive of myocardial ischemia, or (ii) new ischemic ECG changes or new LBBB, or (iii) angiographic loss of patency of a major coronary artery or a side branch or persistent slow- or no-flow or embolization, or (iv) imaging demonstration of new loss of viable myocardium or new regional wall motion abnormality are required.
4. Stent thrombosis associated with MI: Detected by coronary angiography or autopsy in the setting of myocardial ischemia and with a rise and/or fall of cardiac biomarkers with at least one value above the 99^th percentile
5. CABG associated MI: Elevation of cardiac biomarker values >10 x 99^th percentile URL in patients with normal baseline cTn values. In addition, either (i) new pathologic Q waves or new LBBB, or (ii) angiographic documented new graft of native coronary artery occlusion, or (iii) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality.

The joint task force further refined the definition of MI

• Type 1 (spontaneous MI): MI consequent to a pathologic process in the wall of the coronary artery (e.g., plaque erosion/rupture, fissuring, or dissection), resulting in intra luminal thrombus
• Type 2 (MI secondary to an ischemic imbalance): MI consequent to increased oxygen demand or decreased supply (e.g., coronary endothelial dysfunction, coronary artery spasm, coronary artery embolus, anemia, tachy-/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 blood
• Type 4a (MI related to PCI)
• Type 4b (MI related to stent thrombosis)
• Type 5 (MI related to CABG)

Thygesen K, Alpert JS, Jaffe AS, et al. Third universal definition of myocardial infarction. Circulation 2012;126(16):2020-35.