Genetics of Sudden Cardiac Death

Advances in genetic testing technology have led to a proliferation of new genetic tests and accelerated developments in the field of cardiovascular genetic medicine. These advances enhance presymptomatic diagnosis and can establish a definitive molecular diagnosis for symptomatic patients at risk for sudden cardiac death. Most importantly, genotype-phenotype correlations can add important information for predicting outcome and selecting treatment for patients with inherited arrhythmic disorders. This paper reviews the current data regarding genotype-phenotype correlations and the role of clinical genetic testing in diagnosis, prognosis, and management of inheritable disorders leading to sudden cardiac death.     

Prevention of Sudden Cardiac Death

Although the annual incidence of sudden cardiac death (SCD) is dropping in the United States, therapies for the patient who has survived a SCD episode or is at high risk of developing SCD in the future are now well established. The implantable cardioverter defibrillator (ICD) has emerged from a series of well done randomized clinical trials of the 1990s as providing a survival benefit in carefully defined patient groups with low ejection fraction of any cause. Patients with either an ischemic or idiopathic dilated cardiomyopathy and an EF ≤35% show a significant survival benefit with the ICD and maximal medical therapy. Many challenging patients (e.g., those with long QT syndrome or Brugada syndrome) who have a reasonably high incidence of sudden death have not been the subject of clinical trials involving the ICD and therapy depends on risk stratification that is currently not completely agreed upon. An exciting research frontier of the future will be those that attempt to integrate the appropriate role of the ICD with the ability of chronic resynchronization therapy to enhance left ventricular function in the damaged ventricle.     

Sudden Cardiac Death in Multi-Ethnic Populations

Risk of sudden cardiac death (SCD) varies greatly by ethnicity, and is particularly high in African Americans as compared to Caucasians. The reasons for these racial differences are unclear but are likely multifactorial. Possible differences in coronary and non-coronary risk factors, socioeconomic factors, and genetic factors should all be considered when investigating this observed racial disproportionality in SCD risk. Furthermore, there is a relative paucity of data on the risk of SCD in non-African American minorities, including Asian Americans and Latinos. In this paper, we will review traditional and contemporary data describing these racial differences and potential explanations for them. A careful examination of the racial differences in SCD risk can not only assist in identifying high risk populations and those who may be targeted for early intervention, but can also provide insight into the pathophysiologic mechanisms of SCD.     

Sudden Cardiac Death in Young Adult

Cardiovascular disease represents one of the most important public health problem in the Western countries, with sudden cardiac death (SCD) being the most common cause of death in adults under 65 years of age. The objective of the present study is to evaluate the leading causes of SCD in young adults who died suddenly in Northern Portugal between 2007 and 2012. This study included 288 cases of 20- to 45-year-old adults who died suddenly of a cardiac cause and whose forensic autopsy was performed in the North Branch of the National Institute of Legal Medicine and Forensic Sciences between 2007 and 2012. Data included the cause of death, forensic autopsy findings, previous medical history and cardiovascular risk factors. The mean age of the population was 37.36 years. Coronary artery disease (CAD) was the leading cause of death, representing 55.6 % of all cases (92.5 % of men and 7.5 % of women). Females died mostly from probable primary arrhythmia. From those who died of coronary disease, 72 (25 % of total cases) had histological evidence of a fatal acute infarction. Age, previous coronary disease, hypercholesterolemia, smoking habits and alcohol consumption seem to be associated with an increased risk of SCD by CAD. A total of 55.6 % of deaths were attributed to CAD. Prevention of cardiovascular risk factors should therefore be considered to prevent atherosclerosis in young adults.     

心源性晕厥或猝死的原因分析

分析 32例在入院时或入院后至少发生 1次或 1次以上心源性晕厥或猝死患者的原因及其发作时与发作前、后的常规 12导联心电图或持续心电监视心电图。结果 :引起心源性晕厥或猝死的基本原因可分为以下几种类型 :①冠心病急性或陈旧性心肌梗死 ;②长QT(U)综合征 ;③Brugada综合征 ;④扩张型和肥厚型心肌病 ;⑤特发性巨大异常J波 ;⑥其他原因。上述各种心源性晕厥或猝死患者有各自不同的心电学特征。结论 :心源性晕厥或猝死是由不同原因、不同心电学特征所致的非单一独立的临床实体     

Exercise and the Risk of Sudden Cardiac Death

Sports activity may precipitate acute fatalities in both adults and young competitive athletes with concealed heart diseases. However, the risk-benefit ratio of physical exercise differs among these two age groups. In adolescents and young adults, competitive physical exercise is associated with a significant increase of the risk of sudden death. Sports is not "per se" cause of the enhanced mortality in this age group; rather, it acts as a trigger of cardiac arrest in those athletes who are affected by silent cardiovascular conditions, mostly cardiomyopathy, premature coronary artery disease and congenital coronary anomalies, which predispose to life-threatening ventricular arrhythmias during physical exercise. In adults, on the other hand, physical activity can be regarded as a "two-edged sword": vigorous exertion increases the incidence of acute coronary events in individuals who did not exercise regularly, whereas habitual physical activity reduces the overall risk of myocardial infarction and sudden coronary death by preventing development of coronary artery disease and progression of coronary atherosclerotic lesions.