Creatine kinase isoenzyme is CKMB, which is actually an enzyme found mainly in the myocardium and is a high myocardial-specific enzyme. If a patient has elevated creatine kinase isoenzyme, it is usually considered to have myocardial damage, such as myocarditis or myocardial infarction, but the presence of myocardial infarction in a patient is determined by the dynamic changes in the patient’s electrocardiogram, clinical manifestations, and whether there are dynamic changes in the isoenzyme elevation. If creatine kinase isoenzyme starts to rise within 6h in the case of myocardial infarction, reaches a peak at 24h, and can return to its original level in 3-4 days, if there is a dynamic change in the enzyme peak, it indicates a higher possibility of acute myocardial infarction. Elevation of isoenzymes should also be cross-referenced with other cardiac enzymes that mark myocardial infarction. If there is an increase in troponin and myoglobin at the same time, the diagnosis of acute myocardial infarction is more likely. If the creatine kinase isoenzyme is persistently elevated in combination with a recent history of viral infection, the possibility of viral myocarditis should also be considered in such patients.