CTNS and myocardial ischemia: In accordance with the main guidance document (Fourth Universal Definition of MI), the main criteria for MI are the following: (1) myocardial injury detected using cTns; (2) symptoms of myocardial ischemia; (3) ischemic changes on ECG and, in particular, the appearance of a pathological Q wave; (4) the identification of areas of non-viable myocardium using imaging methods; and (5) the detection of a blood clot in the coronary arteries using CAG or autopsy.