Sudden cardiac death describes the unexpected natural death from a cardiac cause within a short time period, generally ≤ 1 h from the onset of symptoms, in a person without any prior condition that would appear fatal [1, 2]. Such a rapid death is often attributed to a cardiac arrhythmia, but with the advent of monitoring capabilities from implantable cardioverter-defibrillators (ICDs), it is now well recognized that classifications based on clinical circumstances can be misleading and often impossible, because 40% of sudden deaths can be unwitnessed [3]. Only an ECG or a ventricular electrogram recorded from an implanted device at the time of death can provide definitive information about an arrhythmia. Prodromal symptoms are often nonspecific, and even those taken to indicate ischemia (chest pain), a tachyarrhythmia (palpitations), or congestive heart failure symptoms (dyspnea) can only be considered suggestive. For these reasons, total mortality, rather than classifications of cardiac and arrhythmic mortality, should be used as primary objectives for many outcome studies.