Sudden cardiac death was originally defined by the World Health Organization as death within 24 hours of symptom onset, and Kuller et al. used death within 2 hours of symptom onset. It was observed that using this definition of sudden death, 12% of all natural deaths were sudden deaths, and sudden cardiac death accounted for 88% of all naturally occurring sudden deaths. The current definition of sudden cardiac death is a natural death due to cardiac causes preceded by a sudden onset of loss of consciousness within 1 hour after the onset of acute symptoms. Such a death occurs in a patient with or without cardiac disease, but in this patient, the manner and timing of death is unexpected and unanticipated. The emphasis is on natural, sudden onset, rapid, and unanticipated. Risk factors for sudden death: The risk is higher in men than in women. Some studies have shown that the risk of sudden death is mostly positively correlated with hypertension, left ventricular hypertrophy, obesity, and smoking. Heart disease and other conditions that predispose to sudden cardiac death are: coronary artery disease, including acute coronary syndrome, ischemic cardiomyopathy, etc. Cardiac diseases, including hypertrophic cardiomyopathy, dilated cardiomyopathy, left ventricular hypertrophy, myocarditis, hypertension, arrhythmogenic right ventricular dysplasia, heart valve disease, congenital heart disease, etc. Primary cardiac abnormalities, including pre-excitation syndrome, long QT syndrome, Brugada syndrome, etc. There is a bimodal phenomenon of sudden death, with the first peak in the first 6 months of life, called sudden infant death syndrome, and the second peak between 45 and 75 years of age, associated with the age of onset of coronary heart disease. The incidence of sudden death in children is very low, being only 2.5% of their total mortality rate in those aged 1 to 22 years. Sudden cardiac death in young people occurs mainly in the presence of underlying heart disease, most of whose heart disease is congenital. in adults aged 18 to 25 years, alcoholism and non-coronary heart disease are the main causes. In recent years, there are often soccer and basketball players who died suddenly on the playing field, and their autopsies revealed a high incidence of hypertrophic cardiomyopathy and abnormal coronary arteries, while most of those over 35 years old showed severe coronary artery sclerosis, and from the coronary artery pachymetry results done by the author, the age of onset of coronary heart disease has advanced in recent years. In the case of underlying heart disease, exercise and excessive mental stress are harmful. The toxic effect of alcohol on the heart is dose-related, and each person’s tolerance to alcohol is not consistent, it is certain that the amount of pure ethanol is about 125ml/d, that is, 150g of liquor (three or two bottles of liquor) and four bottles of beer per day for more than 10 years can cause alcoholic cardiomyopathy. The clinical manifestations of sudden cardiac death have four components: 1. prodromal symptoms include aggravation of existing cardiac disease, such as chest pain, dyspnea, palpitations or fatigue, but all prodromal symptoms are neither sensitive nor specific. 2. Occurrence of the event The patient has an acute onset of rapid heartbeat, dizziness, dyspnea, weakness and chest pain, and syncope. The duration is brief. This period represents the occurrence of myocardial ischemia and arrhythmia in the heart, as well as the disturbance of the entire internal environment of myocardial metabolism. 3.Cardiac arrest Characterized by loss of consciousness, respiratory arrest and loss of pulse. 4. biological death Without therapeutic intervention, ventricular fibrillation lasting 4-6 minutes causes irreversible brain damage. lack of life support treatment within 8 minutes, i.e., resuscitation and prolonged survival, is almost impossible. The identification of high-risk patients relies on ambulatory ECG monitoring, active plate load test, signal-averaged ECG, heart rate variability, and intracardiac electrophysiological examination. Each of these means has its clinical significance, but all have limitations. Once abnormalities are detected by each of these means, they should be treated aggressively.