ACS stands for acute coronary syndrome, a group of clinical syndromes due to acute myocardial ischemia. It includes non-ST-segment elevation myocardial infarction, ST-segment elevation myocardial infarction, and unstable angina pectoris. These conditions can be collectively referred to as acute coronary syndromes. When a patient is suspected of having acute coronary syndrome, an electrocardiogram and myocardial enzymes must be performed in a timely manner to observe whether there are dynamic changes in the electrocardiogram and whether there are elevations in myocardial enzymes. If an acute myocardial infarction does occur, coronary intervention should be combined to help prevent malignant events.