Serum cardiac enzymes are enzymes in cardiomyocytes that catalyze cardiomyocyte metabolism and regulate cardiomyocyte electrical activity. If myocardial cells are necrotic or ruptured, even if the weight of myocardial necrosis is less than 1g, the released enzymes can be detected within a certain period of time. In this case, the ECG is often difficult to detect. Therefore, the clinical level of myocardial enzymes is usually used to indirectly measure the degree of myocardial cell damage. Myocardial enzyme changes in acute myocardial infarction have a characteristic dynamic evolution. Currently, it is recognized that creatine kinase (CK) has higher diagnostic significance than glutamate transaminase (AST) and lactate dehydrogenase (LDH), and is a sensitive indicator for early diagnosis of acute myocardial infarction. However, myocardial enzymes are elevated whenever the level of myocardial cell necrosis reaches a certain level, which is not only present in acute myocardial infarction. AST is a non-specific myocardial enzyme, which can be elevated in addition to acute myocardial infarction. AST is a non-specific myocardial enzyme that can be elevated in heart failure, shock, hepatitis, and anticoagulant warfarin, but its peak value is generally not as high as in acute myocardial infarction. For example, AST can also be significantly increased in liver disease, but the peak is much lower than that in acute myocardial infarction. In this case, simultaneous measurement of AST and ALT can assist in the differential diagnosis. In acute myocardial infarction, ALT is mildly elevated, much less than AST, and in most cases of liver disease, ALT is higher than AST. It is generally believed that the ideal biochemical index to reflect acute myocardial injury should be highly cardiac specific, elevated soon after myocardial injury, persist for a long time, and easy to detect.