SOTALOL AND TYPE-IA DRUGS IN COMBINATION PREVENT RECURRENCE OF SUSTAINED VENTRICULAR-TACHYCARDIA

Objectives. This study assessed the efficacy of the combination of sotalol and either quinidine or procainamide in preventing sustained ventricular tachycardia inducibility and recurrence and prospectively evaluated the ability of the drug combination to prevent ventricular tachycardia recurrence when the arrhythmia remained inducible but was modified. Background. Individual antiarrhythmic drugs are often ineffective in preventing the induction and recurrence of sustained ventricular tachycardia. Beta-adrenergic blockade and prolongation of refractoriness may be important components of successful antiarrhythmic therapy in patients with ventricular tachycardia. We reasoned that the combination of sotalol, which has beta-adrenergic blocking properties and prolongs ventricular refractoriness, and quinidine or procainamide, two agents that slow conduction and prolong refractory periods, would be effective therapy in such patients. Methods. We administered low dose sotalol (205 +/- 84 mg/day) plus quinidine sulfate (1,278 +/- 479 mg/day) or procainamide (2,393 +/- 1,423 mg/day) to 50 patients with spontaneous sustained ventricular tachycardia or fibrillation and inducible ventricular tachycardia. Results. In 21 (46%) of 46 patients, ventricular tachycardia was rendered noninducible at electrophysiologic study (group I), and in 17 patients (37%), inducible tachycardia was modified according to prospectively identified criteria (group II), for a combined 83% response rate. Ventricular refractory periods increased from 252 +/- 24 to 316 +/- 28 ms and from 265 +/- 33 to 316 +/- 24 ms in groups I and II, respectively (p < 0.001), but from 234 +/- 19 to only 286 +/- 13 ms in the group of patients with unmodified ventricular tachycardia inducibility (n = 8, group III, p < 0.001). Cycle length of induced ventricular tachycardia slowed from 324 +/- 62 to 432 +/- 70 ms in group II patients (p < 0.001), whereas it slowed less in group III patients (279 +/- 73 to 314 +/- 63 ms, p = NS). Forty-two of the 50 patients (including all patients in groups I and II) were discharged on treatment with the drug combination. After 25 +/- 19 months of follow-up, the actuarial recurrence rate of ventricular tachycardia was 6%, 6% and 11% at 1, 2 and 3 years, respectively. Among patients in whom this drug combination was unsuccessful at electrophysiologic study (group III) and in those who received alternative therapy after combination therapy was discontinued because of side effects, actuarial recurrence rates were 9%, 14% and 32% at 1, 2 and 3 years, respectively. Conclusions. The combination of sotalol plus quinidine or procainamide markedly prolongs ventricular refractoriness and slows induced ventricular tachycardia in a high proportion of patients. Patients with modified or noninducible tachycardia have a low rate of arrhythmia recurrence in follow-up. This drug combination deserves further evaluation.