Effect of Sotalol on Arrhythmias and Exercise Tolerance in Patients with Hypertrophic Cardiomyopathy

Abstract

The effect of sotalol on exercise tolerance and incidence of arrhythmias was studied in 30 patients with hypertrophic cardiomyopathy (HCM). In this short-term, double-blind, crossover study, exercise time on sotalol (320 mg/day) was significantly longer than on placebo (10.6 ± 4.0 vs. 9.4 ± 3.6 min; p < 0.01). Sotalol eliminated supraventricular arrhythmias in 6 of 7 patients (p < 0.03) and suppressed ventricular arrhythmias in 7 of 13 patients in whom they were present on placebo (p < 0.05). Ventricular tachycardia was abolished in 4 of 8 patients, but appeared during sotalol treatment in 1 patient who was free of repetitive arrhythmias on placebo. Twenty-five patients who had better exercise tolerance on sotalol than on placebo and did not experience aggravation of arrhythmia entered a 6-month prospective, open-label treatment with sotalol (160-480 mg/day, mean ± SD377 ± 94). One patient was withdrawn after 1 month because of bronchospasm. Mean exercise time improved from 9.8 ± 3.6 min on placebo to 12.7 ± 3.2 min (p < 0.01) after 6 months of treatment with sotalol. During the prospective follow-up, sotalol abolished ventricular tachycardia in all 6 patients after 1 month (p = 0.022), and in 4 of 6 patients (p > 0.2) after 6 months of treatment. It is concluded that sotalol significantly improves exercise tolerance and is effective in suppressing both supraventricular and ventricular arrhythmias in patients with HCM.