Sudden cardiac death: the size of the problem

Sudden cardiac death (SCD) is the result of an unresuscitated cardiac arrest, which may be caused by almost all known heart diseases. Most cardiac arrests are due to rapid and/or chaotic activity of the heart (ventricular tachycardia or fibrillation); some are due to extreme slowing of the heart (bradyarrhythmia). These events are called life-threatening arrhythmia and cause sudden death.