The common causes of sudden angina are as follows: 1. Some patients have atherosclerotic stenosis in the coronary arteries, which is triggered by overexertion, emotional excitement, cold stimulation, smoking and other factors, resulting in the rupture of the plaque in the coronary artery lumen, and the platelets in the blood are activated and gather on the surface of the ruptured plaque to form a thrombus. The thrombus suddenly blocks the coronary artery, causing acute ischemia and narrowing of the lumen; 2. In some patients, the lumen itself does not have problems, but some acute factors cause the lumen to spasm, resulting in transient myocardial ischemia and sudden onset of angina pectoris.