Latest data from Secondary Prevention Implantable Cardioverter-Defibrillator Trials

The Antiarrhythmics Versus Implantable Cardioverter-Defibrillator (AVID), Cardiac Arrest Study Hamburg (CASH) and the Canadian Implantable Defibrillator Study (CIDS) trials demonstrated that the implantable cardioverter-defibrillator (ICD) was superior to best drug therapy for prolonging survival inpatients with sustained ventricular tachycardia/fibrillation (VT/VF). Substudies of AVID demonstrated that ICD benefit was highest in patients with ejection fractions < 35%, concomitant beta-blocker therapy and concomitant beta-blocker therapy did not explain the differences in ICD versus amiodarone benefit. The AVID registry substudies demonstrated high mortality rates in all subgroups including VT/VF from transient/correctable causes. ICD therapy reduced mortality in patients with unexplained syncope and inducible VT. Adjusted mortality rates were lower in patients presenting with an out-of-hospital versus and in-hospital arrest. Three-year survival rates trended lower in patients with stable versus unstable VT. A CASH substudy demonstrated that VT inducibility predicted a group of patients with lower survival rates tha noninducible patients. CIDS substudied demonstrated that patients most likely to benefit from an ICD were ≥ 70 years old, had ejection fractions ≤ 35% and NYHA class III/IV functional class.