CK-MB can appear in the circulating blood in the early stage of myocardial injury, start to increase at -6 hours after myocardial injury, reach a peak within 12-24 hours, and then drop to normal water for 36-72 hours). Therefore, serum CK-MB levels are of great significance for the diagnosis of acute myocardial infarction, myocarditis and other myocardial ischemic diseases