Antiarrhythmic efficacy of sotalol--noncardioselective beta-adrenergic blocking agent with class III antiarrhythmic action was evaluated in 34 patients [pts] (mean age 55 +/- 11) with chronic ventricular arrhythmias and coronary artery disease, 38% with previous myocardial infarction. Two schedules of dosing were tested: 3 x 80 mg and 2 x 160 mg during 28 days of therapy. Pts with Lown class II and IV arrhythmia derived from 24-hours Holter recording were assigned. Ventricular premature complexes [VPCs] and couplets reduction by 80% and total elimination of runs defined antiarrhythmic efficacy. Proarrhythmia was defined by four times increase in VPCs, ten times increase in couplets and runs or sustained VT episodes.
Results: Antiarrhythmic efficacy of two doses of sotalol according to study criterion was: 31% for lower dose (3 x 80 mg) and 24% for higher dose (2 x 160 mg). Overall efficacy for both doses was 55%. According to Morganroth criterion, lower dose was effective in 29% pts and both doses, lower and higher, in 41% pts. According to other commonly used criterion: 70% VPCs reduction, 90% couplets reduction and total elimination of runs, lower dose of sotalol was effective in 32% pts and both doses in 47% pts. Significant reduction of heart rate and prolongation of QT and QTc were observed. In 3 pts QT was prolonged over 500 ms. Proarrhythmia according to Velebit criterion was suspected in one patient after one week of 3 x 80 mg teratment which caused premature cessation of therapy. No significant abnormalities in laboratory values were observed.
Conclusions: Antiarrhythmic efficacy of sotalol was comparable to other studies. Its value in pts with malignant ventricular tachyarrhythmias: sustained ventricular tachycardia and ventricular fibrillation requires further studies with higher number of patients.