The diagnostic criteria for myocarditis are as follows: 1. Within 3 weeks after viral infection: severe weakness, chest tightness, dizziness, markedly diminished apical first heart sound, diastolic gallop rhythm, pericardial sassafras sound, heart enlargement, heart failure, and As syndrome. Any of the following: a: sinus tachycardia, atrioventricular block, sinus atrioventricular block, or narrative block; b: multiple, paired premature ventricular beats, autonomous atrial or junctional tachycardia, paroxysmal or nonparoxysmal ventricular tachycardia, atrial or ventricular flutter or fibrillation; c: horizontal or downward sloping downward shift of the ST segment in two or more leads ≥0.01mv or ST segment elevation or The presence of abnormal Q waves. 2, within 3 weeks after viral infection: severe weakness, chest tightness, dizziness, significantly weakened apical first heart sound, diastolic gallop rhythm, pericardial sassafras sound, heart enlargement, heart failure, A – S syndrome. Combination of any 2 of the following: a significantly increased troponin, CK_MB, ultrasound indicating enlarged heart chambers or abnormal ventricular wall activity and/or nuclear cardiac function tests confirming reduced left ventricular systolic or diastolic function.