Predictors of device activation for ventricular arrhythmias and survival in patients with implantable pacemakers/defibrillators. CADENCE Investigators.

Predictors of survival and arrhythmia recurrence for patients with implanted defibrillators have been reported but patients with sustained, well-tolerated ventricular tachycardia were often excluded from these trials. Arrhythmia recurrence and survival in populations including these patients have been less well studied. The purpose of the present study was to examine predictors of spontaneous ventricular arrhythmias and mortality in patients who received a tiered therapy antitachycardia pacemaker/defibrillator for ventricular tachycardia, fibrillation, or both. Three hundred thirty-seven patients who received a Ventritex CADENCE tiered therapy antitachycardia device at one of 19 participating centers between July 11, 1989 and March 4, 1991 are included in this retrospective analysis. Diagnostic summary data and stored electrograms telemetered from the implanted device were assessed to determine characteristics of recurrent arrhythmias. Mean follow-up was 360 +/- 10 (SEM) days. Thirty-three patients died during follow-up. At least one recurrent ventricular arrhythmia was observed in 205 patients (61%). A total of 7,539 episodes were observed with a mean of 37 +/- 5 per patient. Patients with recurrent ventricular arrhythmias were slightly but significantly older (64 +/- 0.7 vs 59 +/- 1.2 years; P < 0.001) but were not distinguished by gender or underlying structural disease. Patients whose presenting arrhythmia was monomorphic ventricular tachycardia were more likely to experience recurrent ventricular arrhythmias (69% recurrence rate) than patients presenting with ventricular fibrillation or polymorphic ventricular tachycardia (46% recurrence rate; P < 0.001). Cycle length of spontaneous tachycardia was also a predictor of arrhythmia recurrence. Patients having slower ventricular arrhythmias were less likely to remain recurrence free. Mean left ventricular ejection fraction was similar for patients with and without recurrences. Younger age and absence of arrhythmia recurrence but not presenting arrhythmia were predictors of survival. We conclude that age and presentation with monomorphic ventricular tachycardia are important predictors of arrhythmia recurrence for this patient population. Exclusion of patients with monomorphic ventricular tachycardia underestimates the rate of recurrent ventricular arrhythmias and utilization of device therapy.