Cardiac enzymes are a general term for a variety of enzymes present in the heart muscle, including aspartate aminotransferase, lactate dehydrogenase, creatine kinase and its isoenzymes, and alpha-hydroxybutyrate dehydrogenase. The elevation of myocardial enzymes has different significance in clinical practice. 1. Creatine kinase and its isoenzymes: Elevation of these two enzymes is commonly seen in acute myocardial infarction, and elevation of creatine kinase and its isoenzymes may also be seen in other myocardial injuries such as angina pectoris and pericarditis. In addition, creatine kinase may be elevated in progressive myotonic dystrophy, polymyositis, and skeletal muscle injury, but the elevation is mainly in creatine kinase isoenzymes. In addition, cerebrovascular accidents, brain surgery, and severe smooth muscle injuries, such as intestinal obstruction, may also increase creatine kinase isoenzymes in the cerebral form. Patients with hypothyroidism may also see an increase in creatine kinase, and serum creatine kinase may also increase after strenuous exercise. 2, lactate dehydrogenase: elevated lactate dehydrogenase is seen in acute myocardial infarction, viral hepatitis cirrhosis, and bone disease. In addition, lactate dehydrogenase can also be elevated when malignant tumors develop to a severe stage. In addition, lactate dehydrogenase in the urine of patients with chronic glomerulonephritis, systemic lupus erythematosus, and malignant tumors of the bladder and kidney can be 3-6 times higher than normal. Lactate dehydrogenase is also elevated in the cerebrospinal fluid of patients with subarachnoid hemorrhage, cerebrovascular thrombosis and hemorrhage. 3. a-hydroxybutyrate dehydrogenase: elevation of this enzyme is seen in acute myocardial infarction, and also in active rheumatic myocarditis, acute viral myocarditis, and hemolytic anemia. In addition, a-hydroxybutyrate dehydrogenase is also elevated in some liver patients. 4. aspartate aminotransferase: measurement of aspartate aminotransferase can reflect the degree of hepatocyte damage and is commonly seen in the following diseases: acute myocardial infarction, liver disease, others like progressive myotonic dystrophy, dermatomyositis, pulmonary embolism, acute pancreatitis, muscle contusion the enzyme is also elevated. Myocardial enzyme profile is a system of enzymes that are widely present in the transverse muscle of the heart and are released into the blood when the myocardium is injured, and measuring the level of myocardial enzymes in the blood is an appreciable indicator of myocardial injury. Myocardial enzyme profile is particularly important for the diagnosis and prognosis of acute myocardial infarction. Symptoms of chest pain, electrocardiographic changes, and elevated myocardial enzymes are essential criteria for the diagnosis of acute myocardial infarction.