Sotalol Is More Powerful Than Propranolol in Suppressing Complex Ventricular Arrhythmias

Background: Sotalol has combined type II and type III antiarrhythmic properties. Although the β-blocking action of sotalol is thought to contribute to its antiarrhythmic actions, few data are available from direct comparative clinical trials with pure β-blocking drugs.

Methods and Results: In this double-blind, randomized, multicenter, placebo-controlled, parallel study, we have compared the antiarrhythmic efficacy and safety of treatment with sotalol vs propranolol in 181 patients with organic heart disease and frequent (> 30 ventricu lar premature complexes [VPCs]/h) repetitive ventricular premature complexes. Eighty-seven were randomized to receive sotalol and 94 received propranolol. The demographic and clini cal characteristics of the two groups were identical, and the majority of patients had coronary artery disease or hypertensive heart disease. Most patients had a long-standing history (> 5 years) of ventricular arrhythmias and, in a significant proportion, antiarrhythmic therapy with other drugs had failed in the past. After withdrawal of all antiarrhythmic drugs and 1 week of placebo, qualified patients were randomized to sotalol (320 mg/day) or propranolol (120 mg/day). Patients not achieving adequate response were given higher doses of sotalol (640 mg/day) or propranolol (240 mg/day). At baseline, both groups had comparable frequency of total VPCs/hour (274/h and 255/h for sotalol and propranolol groups, respectively) which was reduced to 71 VPCs/h and 109/VPCs/h, respectively, at the end of phase 1. At final eval uation there was a significantly greater response to sotalol as demonstrated by 80% reduction in VPCs/hour with sotalol compared with only 50% reduction noted in the propranolol group. Adequate therapeutic response was also achieved in a significantly greater percentage of patients on sotalol compared with propranolol (56% vs 29%. P = .02). Sotalol was also superior to propranolol in suppressing the VT events/day during phase 1 (89% vs 78% reduc tion in VT events/days, P < .05). Sotalol was more effective than propranolol in all subgroups and in patients with heart rate < 75 beats per minute.

Conclusions: Sotalol is more powerful than propranolol in suppressing ventricular arrhyth mias documented on Holter recordings. The superiority of sotalol appears to be related to its combined class II and class III antiarrhythmic actions.