Background: Unstable angina pectoris(UAP)is a intermidiate state of stable angina pectoris(SAP)and acute myocardial infarction(AMI). It can revert to SAP and develop to AMI in short time.

• 背景：不稳定性心绞痛(unstable angina pectoris, UAP)是介于稳定性心绞痛(stable angina pectoris, SAP)和急性心肌梗塞（acute myocardial infarction，AMI）之间的临界状态，可逆转为稳定性心绞痛，也可能迅速进展为急性心肌梗塞。