Fast Five Quiz: Myocardial Infarction Clinical Keys

According to the Fourth Universal Definition of Myocardial Infarction, detection of an elevated cTn value above the 99th percentile upper reference limit is defined as myocardial injury. The injury is considered acute if there is a rise in cTn values, a fall in cTn values, or both.

The criteria for type 1 MI includes detection of a rise and/or fall of cTn values with at least one value above the 99th percentile and with at least one of the following:

Symptoms of acute myocardial ischemia
New ischemic ECG changes
Development of pathologic Q waves
Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischemic etiology
Identification of a coronary thrombus by angiography including intracoronary imaging or at autopsy

The criteria for type 2 MI includes detection of a rise and/or fall of cTn with at least one value above the 99th percentile and evidence of an imbalance between myocardial oxygen supply and demand unrelated to coronary thrombosis, requiring at least one of the following:

Symptoms of acute myocardial ischemia
New ischemic ECG changes
Development of pathologic Q waves
Imaging evidence of new loss of viable myocardium or a new regional wall-motion abnormality in a pattern consistent with an ischemic etiology

Coronary intervention–related MI is arbitrarily defined by elevation of cTn values greater than five times the 99th percentile upper reference limit in patients with normal baseline values. Coronary artery bypass grafting–related MI is arbitrarily defined as elevation of cTn values > 10 times the 99th percentile URL in patients with normal baseline cTn values.

Patients may have elevated cTn values and marked decreases in ejection fraction due to sepsis caused by endotoxin, with myocardial function recovering completely with normal ejection fraction once the sepsis is treated.