Abstract
Ventricular fibrillation (VF) and hemodynamically unstable ventricular tachycardia (VT) likely remain the most common initiating and potentially reversible mechanisms of out-of-hospital cardiac arrest and sudden cardiac death (SCD). Defibrillation is the only predictably effective therapy for reverting VF and pulseless VT to an effective rhythm for restoration of blood flow. Current indications for implantation of implantable cardioverter-defibrillators are the result of risk stratification strategies that can be divided as follows: (1) secondary prevention indications; (2) primary prevention in high-risk groups with acquired diseases; and (3) SCD prevention in selected patients with specific inherited arrhythmogenic syndromes or less common acquired diseases. Further improvement and understanding of different risk stratification strategies will eventually identify individuals at specific risk for SCD and, hence, determine the type of preventive intervention required for small, high-risk subsets of individuals, who are currently diluted within larger population groups or the general population that account for the majority of SCD victims.
