The epidemiology of ventricular tachycardia/fibrillation (VT/VF) and sudden cardiac death (SCD) must be explored from multiple aspects, each of which contributes insights into the problem and no one of which exerts exclusive dominance for preventive or therapeutic strategies. These include: (1) population dynamics, using conventional epidemiologic approaches; (2) risk as a function of time from an index event; (3) conditioning risk factors, based on the presence of underlying disease states; (4) transient risk factors that are dynamic and trigger a potentially fatal event at a specific point in time; and (5) "response risk," which refers to individual susceptibility (possibly determined genetically) to the adverse effects of longitudinal and/or dynamic risk factors. Major inroads into profiling individual or population risk of SCD will require better understanding of each of these epidemiologic-clinical-physiologic interactions. The disciplines range from epidemiology, through clinical medicine, to membrane channel physiology, genetic determinants, and molecular biology.