High cardiac enzymes are mainly due to necrotic disintegration of cardiac muscle cells, when the enzymes contained in the cells enter the bloodstream causing elevated cardiac enzymes in the blood. Common cardiac enzymes include lactate dehydrogenase and creatine kinase isoenzyme. Myocardial enzymes are clinically seen in various heart diseases that cause myocardial cell necrosis, implying myocardial cell necrosis, and are most commonly used in the diagnosis of acute myocardial infarction. In acute myocardial infarction, myocardial enzymes can be elevated several times or even hundreds of times, and can also be seen in patients with acute myocarditis, severe heart failure, and secondary myocardial damage caused by acute infection of other organs such as acute pancreatitis. The severity of myocardial enzyme elevation is directly related to the extent of myocardial damage; the greater the extent of myocardial damage, the higher the degree of myocardial enzyme elevation. Elevation of cardiac enzymes is currently used clinically to diagnose acute myocardial infarction. It also needs to be differentiated from other diseases that cause elevated cardiac enzymes. Lactate dehydrogenase rises within 6-10 hours after the onset of myocardial infarction, peaks in 2-3 days, and returns to normal in 1-2 weeks; creatine kinase isoenzyme rises 4 hours after the onset of myocardial infarction, peaks in 12-24 hours, and returns to normal in 3-4 days; the degree of increase can more accurately reflect the extent of infarction, and whether the peak of enzyme appears earlier can help determine the success of thrombolytic therapy.