The effects of oral digoxin therapy in primary mitral leaflet prolapse.

The effects of oral digoxin on symptoms, arrhythmias, exercise tolerance and echocardiographic function in primary mitral leaflet prolapse were studied in 23 patients using a double-blind crossover protocol. Digoxin reduced the incidence and severity of chest pain compared with both the control (P = 0.0002) and placebo (P = 0.0005) periods. We found a high (83%) incidence of predominantly minor arrhythmias on continuous ambulatory monitoring. Digoxin favourably affected the incidence of frequent supraventricular ectopic beats and supraventricular tachycardia but was associated with a significant number (P less than 0.0025) of asymptomatic bradyarrhythmias. In patients with frequent ventricular ectopics, digoxin had no consistent effect. No difference in exercise tolerance between treatment periods was found on maximal treadmill stress testing, but digoxin administration resulted in an increase in echocardiographic mean circumferential fibre shortening velocity (P less than 0.01) and fractional shortening percent (P less than 0.01). This study demonstrates the efficacy of oral digoxin therapy in ameliorating chest pain in patients with primary mitral leaflet prolapse and suggests a favourable effect on supraventricular arrhythmias in such patients.