Design and Results of the Antiarrhythmics vs Implantable Defibrillators (AVID) Registry

Background—The Antiarrhythmics Versus Implantable Defibrillators (AVID) Study compared treatment with implantable cardioverter-defibrillators versus antiarrhythmic drugs in patients with life-threatening ventricular arrhythmias (VAs). AVID maintained a Registry on all patients, randomized or not, with any VA or unexplained syncope who could be considered for either of the treatment strategies. Trial-eligible arrhythmias were the categories of VF cardiac arrest, Syncopal VT, and Symptomatic VT, below. Methods and Results—Of 5989 patients screened, 4595 were registered and 1016 were randomized. Mortality follow-up through 1996 was obtained on the 4219 Registry patients enrolled before 1997 through the National Death Index. Crude mortality rates (mean6SD, follow-up, 16.9611.5 months) were: VF cardiac arrest, 17.0% (n51399, 238 deaths); Syncopal VT, 21.2% (n5598, 127 deaths); Symptomatic VT, 15.8% (n51065, 168 deaths); Stable (asymptomatic) VT, 19.7% (n5497, 98 deaths); VT/VF with transient/correctable cause, 17.8% (n5270, 48 deaths); and Unexplained syncope, 12.3% (n5390, 48 deaths). Conclusions—Patients with seemingly lower-risk or unknown-risk VAs (asymptomatic VT, and VT/VF associated with a transient factor) have a (high) mortality similar to that of higher-risk, AVID-eligible VAs. The similar (and poor) prognosis of most patients with VT/VF suggests the need for reevaluation of a priori risk grouping and raises the question of the appropriate arrhythmia therapy for a broad range of patients. (Circulation. 1999;99:1692-1699.)