RESUMEN
Sotalol is a unique beta-adrenergic blocking agent with additional actions characteristic of Vaughn-Williams class III antiarrhythmic agents in experimental models. To test the efficacy of sotalol to suppress ventricular arrhythmias, a 6 week parallel, placebo-controlled out-patient study of two doses (320 and 640 mg/day, in two divided doses) was performed in four hospitals in 56 patients with chronic premature ventricular complexes at a frequency of 30/h or more (mean +/- SE, 528 +/- 60/h) on 48 hour ambulatory electrocardiographic recording. During a placebo week, no change occurred in arrhythmia frequency (532 +/- 76/h). Subsequent sotalol therapy significantly reduced median arrhythmia frequency in patients receiving both low (n = 19) and high (n = 18) doses compared with that in patients receiving placebo (by 77 and 83%, respectively, versus 6%; p less than 0.001). Twenty-two (59%) of 37 sotalol-treated patients, 11 in each group, reached the prospectively defined criterion of efficacy (greater than or equal to 75% arrhythmia reduction) versus 2 (11%) of 19 placebo control patients (p less than 0.001). Sotalol reduced the median frequency of couplets by 94% (p less than 0.0001) and that of runs by 89% (p less than 0.0007). The electrocardiographic effects of sotalol included reductions in heart rate (by 17 to 27%) and increases in the QTc (by 6 to 9%) and PR (by 6%) intervals. Ejection fraction was unchanged. The most common adverse side effect was fatigue, but drug discontinuation was required in only three patients taking 640 mg/day. No proarrhythmic events or biochemical abnormalities were observed. In summary, sotalol displays significant antiarrhythmic activity of moderately high degree with good tolerance in doses of both 320 and 640 mg/day. Its antiarrhythmic actions are distinguished from those reported for other beta-blockers by its effects on the QTc interval and its moderately high degree of antiarrhythmic activity.