Sudden cardiac death risk stratification and assessment: primary prevention based on ejection fraction criteria.

Sudden cardiac death (SCD) is the prime cause of death in the United States. The trials that focus on identifying and protecting patients at risk of SCD have identified the left ventricular ejection fraction (EF) as the single clinical marker that is most useful for risk assessment and stratification in primary prevention. This article reviews the data from major randomized clinical trials of implantable cardioverter-defibrillator implantation in patients with low EF for the primary prevention of SCD and exposes some of the shortcomings of the EF as a stratifier of mortality risk.