Comparison of efficacy of sotalol and nifekalant for ventricular tachyarrhythmias.

BACKGROUND Suppression of implantable defibrillator discharges associated with ventricular tachyarrhythmia (VTA) has been reported for sotalol. This study aimed to investigate the efficacy of intravenous nifekalant hydrochloride in predicting the effects of oral sotalol. METHODS AND RESULTS The present study included 14 patients who had sustained VTA associated with structural heart disease. All patients also had inducible VTA. To compare the effects of nifekalant and sotalol, programmed electrical stimulation was performed, in the basal state, after nifekalant administration, and after sotalol administration. Nifekalant and sotalol similarly prolonged the corrected QT interval and ventricular effective refractory periods, but the heart rate was slowed by sotalol only. In 4 of 5 patients whose VTA became non-inducible by nifekalant, subsequent treatment with sotalol also suppressed the inducible VTA. In all of the 9 patients non-responding to nifekalant, VTA remained inducible during sotalol treatment. Nifekalant accurately predicted the response to sotalol during electrophysiologic study in 13 of 14 patients. Of 11 patients who remained on sotalol, VTA recurred in 3 non-responders during a follow-up of 46 +/- 11 months. CONCLUSIONS Nifekalant and sotalol had similar effects on inducible VTA. The response of inducible VTA to nifekalant may predict the clinical efficacy of sotalol.