Mechanism of action of sotalol in supraventricular arrhythmias

Sotalol has a virtually unique antiarrhythmic profile in that it combines the properties of the Class II beta-blocking agents with the Class III properties that prolong repolarization. The Class II action exerts a marked effect on atrioventricular nodal conduction and makes sotalol a suitable drug for the treatment of adrenergic-induced supraventricular tachycardias. Sotalol helps to prevent or slow supraventricular arrhythmias involving the atrioventricular node as part of a reentrant pathway and also helps to control the ventricular rate during supraventricular arrhythmias conducted to the ventricles over the normal atrioventricular pathway. The capacity of conduction of accessory pathways is diminished by sotalol, thereby decreasing the ventricular rate during atrial fibrillation in the Wolff-Parkinson-White syndrome. The effects of sotalol on conduction of the cardiac impulse (Class I effects) have been probably overlooked and those on true refractoriness (Class III effects) overestimated.