Sudden cardiac death

SCD continues to be an important cause of death and morbidity. Despite expanding insight into the mechanisms causing SCD, the population at high risk is not being effectively identified. Although there is still much to do in the management phase of SCD (predicting the efficacy of various therapies), recent clinical trials have helped define the relative risks and benefits of therapies in preventing SCD. Trials are underway to determine whether treating other patient populations, including asymptomatic patients after MI, will improve survival rate. The approach to reducing mortality rate will always be multifaceted; primary prevention of coronary artery disease and prompt salvage of jeopardized myocardium are 2 important aspects of this approach. In addition to interventions for MI, such as myocardial revascularization when indicated, simple and easily administered therapies that are likely to remain the most effective prophylactic interventions are aspirin, ACE inhibitors, beta-blockers, and cholesterol-lowering agents. However, the MADIT and AVID data clearly demonstrate a role for ICD therapy in a subgroup of patients who have VT/VF and are at risk of cardiac arrest. Even though the absolute magnitude of benefit associated with ICDs is still to be determined, the AVID study and other recent reports provide convincing evidence that patients who have VT/VF fare better with ICDs than with antiarrhythmic drug therapy. For the high-risk population described in this article, in addition to aggressive anti-ischemic and heart failure therapy, ICDs are now a mainstay of life-saving treatment. Still to be surmounted is the challenge of identifying patients who have nonischemic substrates and of providing them with the appropriate therapy. Guided by genetic studies and new insight into the mechanisms of such problems as congenital long QT syndrome, life-saving and life-enhancing therapies may soon be available for the management of SCD.     

Sudden cardiac death

Opinion statement Sudden cardiac death is often due to a ventricular arrhythmia. When a patient presents with a malignant arrhythmia unrelated to a transient reversible cause, there is a high probability of recurrent arrhythmia and sudden death. Clinical trials have shown a uniform survival benefit from implantable cardioverter-defibrillator (ICD) therapy in survivors of a malignant arrhythmia when compared with drug therapy. However, only 1% to 5% of patients survive an out-of-hospital cardiac arrest, emphasizing the need for primary prevention of sudden death. Clinical trial data available in this regard are largely limited to patients with coronary artery disease (CAD). Mortality can be reduced by the ICD in patients with CAD and depressed left ventricular ejection fraction (LVEF) less than 30%. If left ventricular function is only moderately depressed (LVEF between 30% and 40%), the presence of nonsustained ventricular tachycardia with inducible ventricular arrhythmia at electrophysiologic testing identifies patients who benefit from an ICD. The role of the ICD in primary prevention of sudden death in patients with nonischemic dilated cardiomyopathy is less clear at this time. Preliminary data indicate that the presence of heart failure symptoms in this population increases risk of sudden death that can be prevented by an ICD. Antiarrhythmic drugs have little role in prevention of sudden death; however, drugs that block the effects of β-adrenergic stimulation, angiotensin, and aldosterone reduce mortality partly through their salutary effects on sudden death. Finally, a number of inherited defects of genes coding for ion channels, contractile sarcomeric proteins, and cell-to-cell junction proteins can result in primary electrical abnormalities and sudden death. The ICD is effective for secondary prevention, but its role in primary prevention is controversial and should be based on individual risk factors.     

Sudden cardiac death

Opinion statement  

心脏性猝死

心脏性猝死（sudden cardiac death，SCD）是指由各种心脏原因引起的自然死亡。发病突然、进展迅速，死亡发生在症状出现后1h内。患者发生猝死事件前可以有心脏疾病表现，但猝死的发生具有无法预测的特点。发生心脏骤停的患者能被成功复苏的机会很小，美国约为15％，而大多国家仅为0—5％。因为绝大多数心脏骤停发生在医院外，不能得到有效的快速治疗干预（如初步的紧急心肺复苏术），仅有发生在医院内或有幸经过初步抢救治疗并及时送至急诊室的心脏骤停患者，有机会得到有效治疗而幸存。因此SCD具有突发、迅速、不可预料和病死率高的特征，是直接危及人们生命的一大杀手。     

Sudden cardiac death in childhood

To evaluate the mechanism of sudden death in childhood and the physical activity levels at the onset of sudden death, we studied the following items: (1) the incidence and the circumstances surrounding sudden death at school in Kanagawa Prefecture, (2) high risk heart diseases detected among healthy school children by heart disease screening, (3) sudden cardiac death or near miss seen in outpatients with heart disease except congenital heart disease. Among total 15,156,346 school children, sudden death was observed in 97 subjects (M:77, F:20). Annual incidence of sudden death was 6.4 per 10(6). Of the 97 subjects, acute heart failure of unknown etiology was found in 60 (62%), cardiovascular disease in 18 (19%), cerebral vascular accidents in 14 (14%) and heat stroke in 5 (5%). Of the 78 subjects (M:64, F:14) considered as sudden cardiac death, 62 (79%) died during sports activities, and 16 (21%) died at rest. Of the 62 subjects, 29 died during track and field activities and 7 while swimming, both in physical education classes. Eighteen died during athletic club activities and 8 during extracurricular activities. Consequently, 54 subjects (87%) died in the presence of a school teacher. Of the 18 subjects with cardiovascular disease, 9 (hypertrophic cardiomyopathy in 3, myocarditis in 3, Kawasaki disease in 2 and long QT in one) were diagnosed initially by the autopsy study. Latent high risk heart diseases, detected among presumably healthy school children by the heart disease screening program, were the following: hypertrophic cardiomyopathy, long QT syndrome, Kawasaki disease and some arrhythmias (ventricular tachycardia, sick sinus syndrome, A-V block and atrial fibrillation). Follow-up observations of outpatients with heart disease revealed the same results as the heart disease screening program. In order to prevent sudden death at school, the following recommendations should be observed: 1) sports directors should learn "sports medicine in childhood", including primary cardiovascular resuscitation, 2) an accurate heart disease screening program should be operated to detect latent high risk heart diseases, advise on adequate medical treatment, and help ensure an appropriate selection of sports activities, 3) comprehensive autopsy studies should be performed.     

Sudden cardiac death in Athletes

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD), and coronary artery anomalies, each with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have emerged in Europe, where the Italian experience of mandatory annual screening of athletes has been the forerunner in efforts to identify individuals at risk. Ongoing clinical efforts are underway to help define the role of implantable cardioverter defibrillators as a preventive measure in appropriate candidates with HCM or ARVD, as well as methods to limit the potential for SCD as a result of chest blows sustained in sports and other recreational activities by means of chest protectors and special sporting equipment for young athletes.     

Sudden cardiac death in athletes

Sudden cardiac death in athletes, although relatively uncommon, is a well-recognized condition generally associated with some congenital abnormalities. It, however, continues to be of vast interest to the public as athletes are seen as a distinct group of individuals who are especially able to tolerate more intense physical activities than the general population. Obviously, intense activities predispose susceptible athletes to sudden cardiac death, hence the importance of pre-participation screening tests. As the cost of healthcare continues to be on the rise, there will be increasing difficulty justifying a nation-wide method of screening cost-effectively. This article is intended to describe the possible underlying causes of sudden cardiac death discovered thus far, as well as methods for detection, pre-participation guidelines, and emerging therapy.     

Sudden cardiac death in athletes

A ‘paradox of sport’ is that in addition to the undisputed health benefits of physical activity, vigorous exertion may transiently increase the risk of acute cardiac events. In general, the risk of sudden cardiac death (SCD) approximately doubles during physical activity and is 2‐ to 3‐fold higher in athletes compared to nonathletes. The incidence of SCD in young athletes is in fact very low, at around 1–3 per 100 000, but attracts much public attention. Variations in incidence figures may be explained by the methodology used for data collection and more importantly by differences between subpopulations of athletes. The incidence of SCD in older (≥35 years) athletes is higher and may be expected to rise, as more and older individuals take part in organized sports. SCD is often the first clinical manifestation of a potentially fatal underlying cardiovascular disorder and usually occurs in previously asymptomatic athletes. In the young (<35 years), SCD is mainly due to congenital/inherited cardiac abnormalities, whilst coronary artery disease (CAD) is the most common cause in older athletes. Cardiac screening including family/personal history, physical examination and resting electrocardiogram (ECG) may identify individuals at risk and has the potential to decrease the risk of SCD in young athletes. Screening including the ECG has a high sensitivity for underlying disease in young athletes, but the specificity needs to be improved, whereas the sensitivity of screening without the use of ECG is very low. The screening modality recommended for young athletes is of limited value in older athletes, who should receive individualized screening with cardiac stress testing for patients with high risk of underlying CAD. As cardiovascular screening will never be able to identify all athletes at risk, adequate preparedness is vital in case of a potentially fatal event at the sporting arena/facility. Firstly, we will review the magnitude of the problem of SCD in athletes of different ages, as well as the aetiology. Secondly, we will focus on how to prevent SCD in athletes of all ages, reviewing cardiovascular screening recommendations as well as emergency preparedness and arena safety.     

Sudden cardiac death in athletes

Sudden cardiac death in athletes is an uncommon but extremely visible event because of the high profile of amateur and professional athletes and the expected excellent health of these athletes. However, paradoxically, athletic performance may immediately increase the risk of ventricular arrhythmias and sudden cardiac death while run reducing atherosclerosis, which thus improves cardiovascular health and longevity. In athletes younger than 30 years, the most common underlying causes are due to inherited heart disease. In the older athletes, sudden death is generally due to arrhythmias in the context of coronary artery disease. Many athletes with aborted sudden death, arrhythmia-related syncope, or high-risk genetic disorders benefit from therapy with implanted cardioverter/defibrillators (ICDs) . Although ICD therapy can effectively abort sudden death, implantation of an ICD generally prohibits an individual from all competitive athletics except low-intensity sports. The screening of athletes has been notoriously inadequate; however, the optimal screening strategies have yet to be determined. Recommendations for participation in competitive athletics generally follow the recently published 36th Bethesda Conference Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities.     

心脏骤停和心脏性猝死

心脏性猝死(SCD)是目前社会关注的热点问题.2005年WHO的数据表明,在全球死于心脑血管疾病的约1700万人群中,40%～50%是SCD.SCD虽然有多种定义,但目前一般认为是在1 h内出现的由于心血管原因导致的非预期死亡事件或无目击者的死亡事件.心脏骤停(SCA)不等同于SCD,SCA如果救治失败会引起真正的SCD.