Sotalol-induced prolongation of the Q-T interval and attacks of unconsciousness.

A case history is reported of a patient who had several episodes of unconsciousness (because of ventricular extrasystole) while on antiarrhythmic and antihypertensive therapy consisting of quinidine (200 mg b. i. d.), sotalol (80 mg b. i. d.) and hydrochlorothiazide (50 mg g. d.). The syncopal attacks continued after discontinuation of quinidine but ended when sotalol was replaced by metoprolol and later on by verapamil. Marked prolongation of the previously normal Q-Tc interval (up to 0.71 s) was observed during the therapy with sotalol alone or combined with quinidine. The syncopal attacks were preceded by feeling of cardiac arrhythmia and they were most likely caused by torsade de pointes tachycardia. The prolongation of the Q-Tc interval by sotalol alone or combined with quinidine was obviously related to the tendency to cardiac arrhythmia and consequent episodes of unconsciousness.