In acute myocardial infarction, LDH starts to increase 8~12 hours after infarction, reaches the peak in 48~72 hours, and gradually returns to normal in 7~12 days. LDH is the abbreviation of lactate dehydrogenase, when infarction and other myocardial injury occurs, myocardial cell membrane rupture, mitochondria, cytoplasmic substances, into the blood caused by the value of the elevated. When myocardial infarction occurs, its change pattern is in myocardial infarction occurred 8~12 hours began to rise, 48~72 hours to reach the peak, 7~12 days gradually return to normal. The specificity of lactate dehydrogenase for the diagnosis of myocardial infarction is low. Other diseases such as myocarditis, hepatitis, liver tumor, hemolytic anemia, leukemia, etc. can also cause abnormal elevation of the value. When myocardial infarction is suspected, it is important to go to the hospital in a timely manner to clarify the cause of the disease as early as possible and to provide targeted treatment, as ventricular fibrillation and cardiac arrest risks may occur if not treated in a timely manner.