Introduction to a compendium on sudden cardiac death: epidemiology, mechanisms, and management.

Sudden cardiac death (SCD) is a devastating complication of many forms of heart disease and on occasion presents in the absence of structural cardiac abnormalities. SCD caused by ventricular arrhythmias is a daunting public health problem with 200 000 to 450 000 events in the United States annually. 1 There are many challenges in the definition, mechanisms, and management of SCD that will be addressed in the chapters of this compendium by leading experts in the field. The compendium will address gaps in our understanding of SCD and resuscitated SCD or sudden cardiac arrest (SCA) from genes to society and highlight opportunities for ongoing investigation. The epidemiology of SCD/SCA is dynamic and heterogeneous as they are the proximate causes of sudden death. Secular trends in incidence, mechanisms, and survival will be addressed, as well as the epidemiology of rarer heritable causes of SCD. The evolution of the causes of SCD/SCA and the relatively poor survival from out of hospital cardiac arrest have motivated studies to better assess risk and to implement strategies for prevention of underlying cardiovas-cular diseases. Basic science studies aimed at understanding the mechanisms of ventricular arrhythmias and the basis of pulseless electric activity (PEA) may afford new insights into to risk assessment and management of arrhythmic and non-arrhythmic causes of SCD/SCA and approaches to cardiac resuscitation. A foundational problem is the absence of a clear understanding of the rates of SCD. Differences in the methods of counting events yield substantial differences in rates of SCD. Differences in data sources yield differences in rates that are complicated by problems in case definition, in part the result of the heterogeneity and changing causes of SCD. Hayashi et al 2 present a contemporary and global epidemiological view of SCD as a public health problem, including a description of the incidence and survival from SCA. The changing epidemiology of cardiovascular disease has been associated with changes in the cause of SCA with a trend away from more treatable ventricular tachycardia (VT)/ventricular fibrillation (VF) to PEA. They consider the general risks associated with coronary heart disease and SCD/SCA, as well as the role of diet, alcohol, kidney disease, sleep apnea, and atrial fibrillation in sudden death risk. The confluence of a vulnerable substrate with specific triggers, such as physical activity , psychosocial determinants, and environmental influences, such as air pollution, is discussed. The epidemiology of SCD in special populations, such as patients …