Sudden cardiac death. Magnitude of the problem, substrate/trigger interaction, and populations at high risk.

Sudden cardiac death continues to be a major clinical and public health problem. Prospective identification of patients at high risk for cardiac arrest is difficult, being limited by the large size of the population subgroups that contain the majority of victims of sudden cardiac death and by the time dependence of risk of sudden death. Pathophysiologically, sudden cardiac death can be viewed as an interaction between structural abnormalities of the heart, transient functional disturbances, and the specific electrophysiologic events responsible for fatal arrhythmias. Further understanding of the dynamics of high-risk populations and mechanisms of sudden death may lead to effective measures for control of risk.