Sotalol infusion in the treatment of supraventricular tachyarrhythmias.

Sotalol, a noncardioselective beta-adrenergic blocking agent without partial agonist activity, has class-3 antiarrhythmic effects. Twenty-nine patients with supraventricular tachyarrhythmias were treated on 31 occasions to determine the effective therapeutic dosage and optimal method of administration. Fifty percent of patients with paroxysmal supraventricular tachycardia, 33 percent of those with atrial flutter, and 20 percent with atrial fibrillation were restored to sinus rhythm by bolus administration; and when sotalol was given by continuous infusion, sinus rhythm was obtained in 100 percent, 86 percent, and 33 percent, respectively. Comparable dosages were given to both responders and nonresponders in the bolus-treated group and higher dosages to nonresponders than to responders in those treated by infusion. Furthermore, plasma levels in nonresponders tended to be higher than in responders. When responders alone were considered, the average dose required was 0.630 +/- 0.090 mg/kg of body weight (+/- SE), and the plasma level obtained was 0.526 +/- 0.088 microgram/ml. No relationship between plasma levels and therapeutic effectiveness was shown. No serious side effects were observed at the dosages used. These data suggest that while no concordance with plasma levels was observed, sotalol given by infusion is an effective therapy for atrial flutter and supra-ventricular tachycardia. It is less effective in atrial fibrillation, where less than half were responders, but a satisfactory reduction in ventricular rate response was obtained. A controlled trial to further substantiate these findings is indicated.