Double-blind placebo-controlled trial of digoxin in symptomatic paroxysmal atrial fibrillation

Abstract

Background - Digoxin is commonly prescribed in symptomatic paroxysmal atrial fibrillation (AF) but has never been evaluated in this condition. Methods and Results - From a multicenter registry, 43 representative patients with frequent symptomatic AF episodes were recruited into a randomized, double-blind crossover comparison of digoxin (serum concentration, 1.29±0.35 nmol/L) and placebo. The study end point was the occurrence of 2 AF episodes (documented by patient-activated monitors), censored at 61 days. The median time to 2 episodes was 13.5 days on placebo and 18.7 days on digoxin (P<0.05). The relative risk (95% CI) of 2 episodes (placebo:digoxin) was 2.19 (1.07 to 4.50). A similar effect was seen on the median time to 1 episode: increased from 3.5 to 5.4 days (P<0.05), relative risk 1.69 (0.88 to 3.24). The mean±SD ventricular rates during AF recordings during placebo and digoxin treatment were 138±32 and 125±35 bpm, respectively (P<0.01). Twenty-four-hour ambulatory ECG recordings did not show significant differences in the frequency or duration of AF or in ventricular rate. Conclusions - Digoxin reduces the frequency of symptomatic AF episodes. However, the estimated effect is small and may be due to a reduction in the ventricular rate or irregularity rather than an antiarrhythmic action.