Features of angina: 1. Location: mostly located in the precordial region or the upper middle part of the sternum, sometimes radiating to the left shoulder, the inner part of the left arm, or the lower jaw. 2, nature: often compressive, constrictive, squeezing-like, etc., but for elderly diabetic patients, it may be just chest tightness without obvious pain. 3, triggers: emotional excitement, full meals, cold, forceful defecation, etc. can trigger an attack of angina, but there are also attacks at rest or during sleep at night (variant angina, a kind of unstable angina). 4. The duration is often less than 15 minutes and rarely exceeds half an hour. If more than half an hour, need to consider the possibility of myocardial infarction. 5.Relief mode: Generally, it can be relieved after stopping the triggering factors, or 2-3 minutes after sublingual nitroglycerin is rapidly relieved, if it is not relieved by repeated containing, it is necessary to consider the possibility of myocardial infarction. 6.Concomitant symptoms, may be accompanied by sweating, weakness, fear of discomfort, etc. 7.Atypical manifestations, some patients come to the hospital with complaints of nausea, vomiting and other gastrointestinal symptoms, which are very easy to be misdiagnosed or missed at this time. Not all chest pain is angina pectoris, angina pectoris is mostly seen in people with high risk factors for coronary heart disease, such as hypertension, diabetes, hyperlipidemia, obesity, long-term smoking history. It needs to be differentiated from neurosis, digestive system diseases such as gastroesophageal reflux, costochondritis, and herpes zoster. Once angina is diagnosed, it needs to be treated professionally by a cardiologist.