Double-blind placebo-controlled trial of digoxin in symptomatic paroxysmalatrial fibrillation

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, do uble-blind crossover comparison of digoxin (serum concentration, 1.29+/-0.3 5 nmol/L) and placebo. The study end point was the occurrence of 2 AF episo des (documented by patient-activated monitors), censored at 61 days. The me dian 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 2.1 9 (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 an d digoxin treatment were 138 +/- 32 and 125 +/- 35 bpm, respectively (P<0.0 1). Twenty-four-hour ambulatory ECC recordings did not show significant dif ferences in the frequency or duration of AF or in ventricular rate. Conclusions-Digoxin reduces the frequency of symptomatic AF episodes. Howev er, the estimated effect is small and may be due to a reduction in the vent ricular rate or irregularity rather than an antiarrhythmic action.