Effects of sotalol on ventricular tachycardia and fibrillation produced by programmed electrical stimulation: comparison with other antiarrhythmic agents.

Sotalol, a beta blocker, is now recognized as an important class III agent. The drug lengthens the action potential in most cardiac tissues without affecting conduction. Several studies have shown that sotalol is very effective in treating life-threatening arrhythmias. One hundred thirty-eight patients with inducible and clinically sustained tachycardia were retrospectively analyzed. With the use of the S1S2S3 stimulation protocol for ventricular tachycardia (VT) induction, sotalol prevented VT/ventricular fibrillation (VF) induction in 45% of the patients; other class I agents prevented VT/VF induction in only 15 to 22%. Data were also analyzed from a prospective multicenter study comparing sotalol with procainamide in suppressing sustained VT in 153 patients with symptomatic sustained VT/VF. With the use of the S1S2S3S4 stimulation protocol, sotalol prevented VT/VF induction in 35% of the patients, whereas procainamide prevented VT/VF induction in only 22% (difference not significant). When patients whose VT induced by the triple-stimuli protocol were excluded, sotalol prevented VT induction in 53%. These findings indicate that the antiarrhythmic effects of sotalol are comparable to those of class I agents in treating malignant arrhythmias. Although more data are needed on the comparative effects of sotalol, available data establish sotalol as an important addition to available antiarrhythmic agents.