Most sudden deaths do not have a precursor; a few people may have fainting, and those with sudden cardiac death may also have symptoms such as severe myocardial ischemia. Sudden death is the sudden and unexpected nonviolent death of an apparently healthy person or a person who is not expected to die, with or without internal or external causes. Most have no obvious precursors. Only a small percentage of patients may have a history of unexplained syncope, poor lifestyle habits, strenuous exercise, and heredity; patients with sudden cardiac death may also have recent symptoms of severe chest tightness, shortness of breath, panic, and dyspnea. In order to prevent the occurrence of sudden death, it is important to maintain good lifestyle habits, avoid smoking and alcohol, ensure adequate sleep, and avoid overwork and emotional stress. If a patient shows symptoms of sudden death, it is necessary to undo the corseted clothing, urgently take chest compressions, artificial respiration and other cardiopulmonary resuscitation measures, and at the same time, call 120 for emergency help.