Cardiac st changes, i.e. upward or downward shift of st segment, represent the electrical activity of myocardium. 1. st-segment elevation: if the st-segment of at least two neighboring leads is elevated more than 0.1mV, acute st-segment elevation myocardial infarction needs to be alerted; if there is chest pain and st-segment elevation, cardiac enzymes and troponin need to be perfected and other tests need to be done. In addition, if st-segment elevation is not seen in ECG in quiet state, but dynamic elevation of st-segment occurs in activity or emotional excitement, it may be related to acute infarction of coronary artery or acute spasm of coronary artery. 2. st-segment depression: if st-segment depression in at least two adjacent leads exceeds 0.05mV, myocardial ischemia should be warned; if st-segment depression occurs after activity or emotional excitement, moderate to severe stenosis of the coronary arteries should be warned, etc. Therefore, if st changes occur in the heart, it may be associated with acute coronary infarction or acute spasm of the coronary arteries. Therefore, if there is a change in the st of the heart, you should actively cooperate with the doctor to improve the relevant examination, to clarify the cause and under the guidance of the doctor to actively treat.