Combined treatment of atrial fibrillation with quinidine and beta-blockers

Abstract

Beta-blockers in combination with quinidine were given to 233 subjects with chronic atrial fibrillation. Conversion to sinus rhythm was obtained in 142 cases (6i%). Propranolol was combined with quinidine in 122 subjects with a percentage of success of 64.8 per cent; alprenolol in 32 with a conversion to sinus rhythm of 56.2 per cent; LB 46 in 44 patients who responded in 65 9 per cent of the cases, and practolol in 35 with a re-establishment of sinus irhythm in 45 7 per cent of the patients. In connexion with the duration of atrial fibrillation, the conversion to sinus rhythm was oblained in 76 4 per cent of the cases with a fibrillation of less than 6 months' duration and in 35 9 per cent with more than 6 months. Toxic effects and intolerance to treatment are clearly less than with quinidine alone, which is probably due to a synergism between the two drugs, and as a consequence of the beta-blocker ,depressant effects on ventricular excitability which avoids the onset of severe arrhythmias.