st changes mainly include st segment elevation, depression, elevation, depression more than normal amplitude suggests the existence of myocardial ischemia, myocardial infarction, etc., more serious. 1. st segment elevation: st segment elevation of 0.1~0.3mV in leads V1~V3 of ECG can be seen in normal people, which is generally of no clinical significance; in addition to leads V1~V3, elevation of more than 0.1mV in the other leads indicates that subepicardial myocardial infarction has occurred, which is more serious and requires immediate medical treatment. 2. st-segment depression: st-segment depression more than 0.05mV, indicating the existence of myocardial ischemia or even the occurrence of subendocardial myocardial infarction, which is more serious and requires immediate medical treatment. Electrocardiogram needs to be recognized and diagnosed by a professional doctor, so it is recommended to ask the doctor to make a diagnosis and follow the doctor’s guidance.