Sudden cardiac death (SCD) is a natural death from cardiac causes characterized by loss of consciousness within one hour of the onset of acute symptoms, and occurs at an unexpected time and in an unexpected form. 90% of sudden cardiac deaths are due to cardiac arrhythmias, 80% of which are caused by tachyarrhythmias (ventricular tachycardia, ventricular fibrillation), and 20% of which are caused by bradyarrhythmias. Another 10% of sudden cardiac deaths are caused by other reasons, including cardiac rupture, pericardial tamponade, and acute left heart failure. Modern medicine’s understanding of sudden death is relatively superficial Although the rapid development of modern medicine has been impressive, and breakthroughs have occurred in many areas, in contrast, modern medicine’s understanding of sudden death is still relatively lagging behind and very superficial. The results of a recent retrospective study of the sudden death population showed that only one-third of the sudden death victims had been medically determined to be at high risk of sudden death, and these people had been detected with coronary artery disease (acute myocardial infarction, unstable angina pectoris), severe arrhythmia, and decreased cardiac function when they sought medical attention. Based on the detected cardiovascular arrhythmias, combined with the epidemiological features of sudden death, the patients were clearly recognized as being at high risk of sudden death. Another 1/3 of the patients who died suddenly also had medical treatment during their lifetime, and certain abnormalities were detected, but these abnormalities were low-predictive and non-specific markers for early warning of sudden death, and were therefore recognized as low or medium risk for sudden death. Another one-third of the sudden death patients, who had no preexisting complaints and never sought medical attention, had sudden death as their first clinical event. The results of this study demonstrate that today’s medical understanding of sudden cardiac death is still very superficial in both theory and practice, and is still challenged by the limited ability of medicine to screen and identify individuals at high risk of sudden death in the general population, which makes sudden cardiac death still a serious public health problem worldwide. Currently, there are more than 20 clinical tests and indicators for screening individuals at high risk of sudden death, but their practical utility in stratifying sudden death risk is still limited, and only some individuals at high risk of sudden death can be screened. In addition, some causes or triggers of sudden death appear temporarily or transiently, which are difficult to be recognized, captured and predicted by the existing testing techniques, especially for primary cardiac diseases, whose ECG abnormalities are mostly hidden; they rarely show abnormalities in ordinary life, and the temporary appearance of the triggers will lead to catastrophic consequences for the patients. If these triggers do not appear at the time, it is still a mystery whether the patient can avoid sudden death in his or her lifetime. However, most sudden cardiac deaths are associated with the Black Triangle of Sudden Death, which consists of a black triangle of cardiac stromal lesions, electrocardiographic stroma, and instability of the internal environment. These three factors can cause sudden death independently, or they can combine and interact with each other to trigger sudden death (Figure 1). In cardiac stromal factors, meaning the presence of cardiovascular diseases that put the patient at high risk of sudden death: coronary artery disease, heart failure, previous history of sudden death, cardiomyopathy, etc., the incidence of sudden death will be 5-10 times higher than that of the general population, and belong to the people at high risk of sudden death. When patients have several diseases at the same time, especially when accompanied by LVEF <40% or even <30%, the chance of sudden death will be further increased. The electrocardiographic substrates include ventricular depolarization and repolarization abnormalities, which are the substrates for the development of ventricular tachycardia and ventricular fibrillation. Abnormalities of ventricular depolarization include widening of the QRS wave, the presence of fragmented waves, and late ventricular potentials, while repolarization abnormalities include prolongation of the QTc, prolongation of the Tp-Te interval, T-wave electrical alternans, and pathologic T waves. These electrocardiographic substrates can occur in patients with organic heart disease or in those with hereditary electrocardiographic disorders. The internal environmental factors of sudden death are not only common, but also variable and variable and insidious. When sudden death occurs, it can act as both a cause and a trigger, making it difficult to prevent. Instability of the internal environment refers mainly to autonomic instability, mostly sympathetic hyperexcitability, vagal hypokalemia, and the most common electrolyte disorder is hypokalemia. In sudden cardiac death, the role of hypokalemia cannot be underestimated. Hypokalemia is present in approximately 50% of survivors of sudden cardiac death who are successfully resuscitated. Hypokalemia can cause a variety of electrocardiographic abnormalities: these include cell membrane potentials that are underpolarized and less negative, attenuated currents in Ikr channels, inhibition of sodium-potassium exchange, and activation of sodium-calcium exchange that causes calcium overload, and delayed posterior depolarization. It is not known whether these people with recurrent hypokalemia have acquired hypokalemia or have abnormal potassium metabolism per se and develop sudden hypokalemic death syndrome. In conclusion, recognizing and conquering sudden death is a long-term and huge challenge for modern medicine. The current situation of sudden cardiac death in China is very serious. Today, the incidence of sudden cardiac death is often difficult to accurately calculate, because the exact incidence can only be obtained through well-designed prospective, epidemiologic studies. In most countries, the total number and incidence of sudden cardiac death are the result of retrospective analyses and estimates. In the United States, calculations and estimates of sudden cardiac death were based on retrospective death certificate analyses and two studies of the Emergency Medical Resuscitation Database. The total number of sudden cardiac deaths in the United States is approximately 300,000 per year, and the annual incidence of sudden cardiac death is 0.19% to 2% in people over 35 years of age, with similar rates in Europe. Epidemiologic data on sudden cardiac death in China are scarce, and there are not enough programs that focus on sudden death. After analyzing the little information available, it is clear that the current situation of sudden cardiac death in China is quite serious. The total number of annual sudden deaths in China is the highest in the world The results of a national fifteen research show that the annual incidence of sudden cardiac death in China is 41.84/100,000, the incidence rate is about 0.04% of the general population, which is lower than that in Europe and the United States, but when further projected on the basis of China's huge population of 1.3 billion people, the total number of sudden cardiac deaths in China is 544,000 people per year, which is the highest in all countries in the world. The total number of sudden deaths in the U.S. is 300,000 per year, which means that one person will die suddenly every minute, while the total number of sudden deaths in China is twice that of the U.S., which means that two people will die suddenly every minute in China. The data also suggests that: with the further aging of China's population, with the increase in the incidence of coronary heart disease, with the number of chronic cardiovascular disease incidence of the number of people, the total number of sudden cardiac deaths in China will be further increased. Sudden death in men is significantly higher than that in women Data from various countries show that the incidence of sudden cardiac death varies largely with the prevalence of coronary heart disease, and women are not susceptible to coronary heart disease due to the protection of estrogen before menopause, so in the young and middle-aged populations, the risk of sudden cardiac death in men is 4"7 times that of women, and estrogen has a physiological preventive role in the protection of sudden death. Epidemiologic data in China show that the annual incidence of sudden cardiac death is 10.5/100,000 in men and 3.6/100,000 in women, which is three times higher in men and similar to foreign data. The risk of coronary events increases in postmenopausal women, and with it the risk of sudden cardiac death, which gradually equalizes with that of men. Cardiovascular disease associated with sudden death The etiology of sudden cardiac death and associated cardiovascular disease in China is less relevant research, several small samples of sudden death patient autopsy data show that the etiology of sudden cardiac death in our country, in order of coronary artery disease (45%-50%), cardiomyopathy (dilated or hypertrophic cardiomyopathy, 20%), rheumatic heart disease (15%), hypertensive heart disease (10%), etc. The main cause of sudden death in pediatrics is coronary artery disease, and the risk of coronary artery events increases in postmenopausal women, which is gradually equal to that of men. The main causes of sudden death in pediatric patients were, in order, structural heart disease, primary electrocardiographic disease (e.g., LQTS syndrome), acquired l "k heart disease, cardiac shock, secondary pulmonary hypertension, and postoperative congenital heart disease. Arrhythmias associated with sudden death In the course of sudden cardiac death due to various cardiovascular or primary cardiovascular diseases, the final passage is almost always via a fatal arrhythmia that triggers sudden death, which occurs mostly with tachyarrhythmias (80%) or bradyarrhythmias (20%). Arrhythmia. Domestic data show that the arrhythmias associated with sudden cardiac death are: tachyarrhythmias (81.2%), including ventricular fibrillation (53.1%) and ventricular tachycardia (28.1%), and bradyarrhythmias (18.8%), including sinus arrest (15.6%) and high atrioventricular block (3.1%). The overall picture of sudden death with arrhythmia is very similar to that abroad. Warnings of intervention epidemiology Intervention epidemiology is a new branch in the field of epidemiologic research, which refers to the epidemiologic understanding of the effectiveness of interventions, the different outcomes of interventions in different populations, and the dynamics of the effects of interventions in the context of effective interventions. After the review and evaluation of the epidemiology of sudden cardiac death intervention, . The actual situation of intervention prevention and treatment in China can be assessed in general, and gaps can be found through comparison. Find the shortcomings. The intervention strategy of sudden death, one is to emphasize the prevention, especially for the prevention of the high-risk group of sudden death, and the second is early treatment, time is life. Past data show that among the various measures for effective prevention and treatment of sudden cardiac death, the most effective measures include four major items such as buried automatic cardiac defibrillator (ICD), public external automated defibrillator (AED), β-blocker thorns, and timely cardiopulmonary resuscitation at the scene of sudden death. The following analyzes the real situation of these four major components in the prevention and treatment of sudden death in China. Buried automatic defibrillator treatment for people at high risk of sudden death According to the modern medical understanding of sudden death, the prevention and treatment population can be divided into three subgroups of high, medium and low risk of sudden death. For people at high risk of sudden death, ICDs are needed to prevent sudden cardiac death, and their efficacy is certain and well-documented. Patients at high risk of sudden death include those who have survived sudden death, who have already suffered sudden cardiac death and were spared due to timely resuscitation, and whose recurrence of sudden death within one year is as high as 47%, and ICDs are commonly used for secondary prevention of sudden death in this group. It has been shown that ICD therapy reduces sudden death in 33% of patients. Thus, there is sufficiently convincing evidence that ICDs reduce mortality in high-risk individuals. Another group of patients at high risk of sudden death are those with severe cardiovascular disease, whose chance of sudden death is 5-10 times higher than that of the general population, and for whom ICDs are feasible for the primary prevention of sudden death. Data show that ICDs can reduce the risk of sudden death by 28% in primary prevention. The relative risk of sudden cardiac death was reduced by 67% compared to other treatments. Therefore, ICDs have definite value in both primary and secondary prevention of sudden death. The application of ICDs in China is not satisfactory. In the United States, where there are 300,000 sudden deaths per year, the annual implantation of ICDs is as high as 200,000 units, and the total number of sudden cardiac deaths in China is 550,000, but the number of new ICDs implanted each year is about 1.5 million. The total number of sudden cardiac deaths in China is 550,000. However, only 1,000 new ICDs are implanted each year, which is 1/400 of the amount implanted in the United States, and the application of ICDs is far from being in place. Public External Automated Defibrillators (AEDs) Sudden cardiac death occurs only rarely in hospitals, with 80% occurring at home or in public. In response to this characteristic of sudden death, public automated external defibrillation (AED) technology has been developed. This technology has had its share of detours in the West, where defibrillation was initially thought to be a specialized, highly technical treatment that could only be used by medical personnel, but modern AEDs have become highly automated and simple to use, and can be used correctly by non-medical personnel with little or no training. Currently, most Western countries have equipped a considerable number of AEDs in places where the public gather, and many cities have AEDs as densely packed and popularized as fire hydrants. In addition, many countries have annual AED training for the public. In the past, the success rate of sudden out-of-hospital death treatment in the United States was only 50%, but today in the United States, fully equipped with AEDs, and have a certain popularity and training in large cities, the success rate of sudden out-of-hospital death treatment has reached 50% -70%. China's application of AEDs to prevent and treat sudden death is far from satisfactory. During the 2008 Olympic Games, under the strong request of the participating countries, China's sports competitions, training venues, and important public places have been equipped with a certain number of AEDs. In the past five years, only the United States, a company ZOU sold 2,500 units of AEDs in China, and other companies have also had a certain amount of sales. Conservative estimates indicate that China is now equipped with about 4,000 AEDs, but survey results show that the actual number of AEDs used in China is still zero, which not only results in hundreds of millions of dollars of wasted funds, but also prevents many sudden deaths from receiving proper treatment. Taking Beijing Airport as an example, there are more than 10 sudden deaths in Beijing International Airport every year, and the airport has been equipped with more than a hundred AEDs which are not useful at all. The main reasons for the zero application of AED in China: ① AED concept lags behind for 20 years, and it is still stipulated that AED must be used by medical personnel; ② China's existing laws and regulations do not protect the use of AED to treat sudden death; ③ There is no publicity, no popularization of AED, and the public does not understand it at all. Effective pharmacologic prevention and treatment of sudden death ICD is mainly applicable to people at high risk of sudden death, while the primary prevention of a much larger number of patients at medium and low risk of sudden death mainly relies on pharmacologic and lifestyle interventions. Pharmacologic therapy not only reduces and terminates episodes of ventricular tachycardia and ventricular fibrillation, but also provides upstream treatment for various cardiovascular diseases that trigger ventricular tachycardia and ventricular fibrillation. ① Beta-blockers: beta-blockers can effectively reduce sudden cardiac death, and the magnitude of its reduction of sudden death is 40%-65%, mainly through the effective blockade of peripheral sympathetic nerve activity and central antiarrhythmic effect to prevent and control sudden death. In addition, it can also reduce ischemic events, reduce the incidence of myocardial infarction, and at the same time, it is also the basic drug for heart failure treatment, which makes β-blockers can not only reduce the total mortality rate, but also significantly reduce the sudden cardiac death, which is applicable to the prevention and treatment of sudden death in patients with organic heart disease, and also applies to all the hereditary, primary cardiac diseases. The proportion of Chinese patients with various cardiovascular diseases taking β-blockers is rising year by year, but the dose taken is low, and many fail to achieve the target goal of treatment. The use of β-blockers for the prevention and treatment of intermediate- and low-risk sudden death patients is still emphasized and under-emphasized in terms of its necessity, dose, and therapeutic target. ② Amiodarone: Several randomized, double-blind, evidence-based medical studies with control groups have confirmed that amiodarone can reduce the incidence of ventricular tachycardia, ventricular fibrillation, and can also significantly reduce sudden cardiac death. ③ Upstream treatment of sudden cardiac death: It has been confirmed that many therapeutic drugs for cardiovascular disease have the effect of indirectly reducing sudden cardiac death, such as angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor antagonists, aldosterone antagonists, and statins. After taking these drugs for a long time, they can effectively prevent the occurrence of sudden cardiac death. The domestic application of these drugs for the treatment of various cardiovascular diseases is not inferior, but the proactive application of these drugs as a preventive treatment for sudden cardiac death alone is still insufficient. Cardiopulmonary resuscitation (CPR) at the scene of sudden death Sudden cardiac death occurring out of hospital has a very low success rate in the past, only Fangju in the United States, 5% in Europe, and the success rate of out-of-hospital treatment in underdeveloped countries is <3%. This situation has improved in recent years, which is related to the large number of equipment and application of aed in public places, the promotion of new procedures of cardiopulmonary resuscitation (CPR), and more popular public resuscitation education. The latest CPR procedures emphasize more on the golden time of the beginning of treatment: it means the beginning of primary resuscitation within 4 min. Data suggest that patient survival can be as high as 60%-75% when the time from sudden death to the first shock is <4 min. When defibrillation is delayed for any reason, timely, standardized and effective cardiopulmonary resuscitation with chest compressions is even more critical, which can partially alleviate the situation where the patient's cardiac output is zero while ventricular fibrillation persists, lengthening the duration of effective treatment. Cardiopulmonary resuscitation (CPR) techniques have long been standardized internationally and are widely available. In many countries, the prevalence of primary CPR has accounted for more than 10% of the national population, and this popularization and training can enable the first witness at the scene of sudden death to perform effective CPR in a timely manner. The popularization and education of CPR in China is still unsatisfactory, which is related to the insufficient attention paid to it by various functional departments, and there are no laws or regulations in China to protect the first witnesses of sudden death from performing case-reported CPR. The general public, even specially trained personnel, stand by for fear of incurring trouble, which delays CPR. Being automatically abandoned, this is China's sudden cardiac death prevention and treatment work in the soft underbelly, weak links, the urgent need to improve the dead ends. In short, the total number of sudden cardiac death in China is the highest in the world, and the gap between the effective prevention and treatment of sudden death and the world level is large, and it still needs the whole society to raise the degree of attention and sincere cooperation. Conquering sudden cardiac death is still a long way to go.