It is called variant angina because its attack characteristics are different from those of ordinary angina in many ways. In addition to the location and nature of the pain, there are differences in the triggers, duration, relief, electrocardiographic characteristics of the attack, and the mechanism of angina pectoris. The most common triggers of angina pectoris are physical activity and emotional excitement, and others can be seen in satiety, cold, smoking and forceful defecation, etc.; the duration is usually 3-5 minutes each time, and rarely exceeds 15 minutes; the symptoms can be relieved after termination of activity and other triggers, and can also be relieved after sublingual nitroglycerin administration. During the attack of angina pectoris, the ECG leads corresponding to the ischemic region show ST-segment downward shift and T-wave depression or inversion. Normal angina is usually caused by fixed stenosis of the coronary arteries. In contrast, the attack of variant angina is not related to activity, and the pain occurs mostly at rest; the attack may be periodic, often occurring at a certain time of day, especially in the middle of the night or early morning; the pain is heavier than that of ordinary angina; the duration is long, often reaching more than 15 minutes, or even 30 minutes; because it is not related to exertion and mental stress, rest cannot relieve the pain, but the administration of nitroglycerin or calcium ion However, the pain can be relieved rapidly with nitroglycerin or the calcium antagonist nifedipine. The pain is not relieved by rest because it is not related to mental exertion. Variant angina is caused by large coronary artery spasm resulting in transmural myocardial ischemia.