Spontaneous Conversion and Maintenance of Sinus Rhythm by Amiodarone in Patients With Heart Failure and Atrial Fibrillation

Background —In a multicenter, double-blind, placebo-controlled study, the long-term effects of amiodarone on morbidity and mortality in patients with congestive heart failure (CHF) and atrial fibrillation (AF) were evaluated during a 4-year period. Methods and Results —Of 667 patients with CHF, 103 (15%) had AF at baseline. Of these, 51 were randomized to amiodarone and 52 to placebo. The group with sinus rhythm and the group in AF were comparable except for a higher proportion of AF in patients with nonischemic versus ischemic cardiomyopathy (41% versus 27%, P <0.005). The mean ventricular response (VR) during AF over 24 hours was reduced by amiodarone at 2 weeks (20%, P =0.001), at 6 months (18%, P =0.001), and at 12 months (16%, P =0.006). Maximal VR was reduced 22% ( P =0.001) at 2 weeks, 19% ( P =0.001) at 6 months, and 14% ( P =0.001) at 12 months. Sixteen of 51 patients on amiodarone and 4 of 52 on placebo converted to sinus rhythm during the study (χ 2 =9.23, P =0.002). During follow-up, 11 of 268 patients in sinus rhythm on amiodarone at baseline and 22 of the 263 in sinus rhythm on placebo developed AF; the difference was significant (χ 2 =12.88, P =0.005). Analysis of total mortality during follow-up showed a significantly lower mortality rate ( P =0.04) in patients in AF at baseline who subsequently converted to sinus rhythm on amiodarone than in those who did not convert to sinus rhythm on the drug. Conclusions —In patients with CHF, amiodarone has a significant potential to spontaneously convert patients in AF to sinus rhythm, with patients who convert having a lower mortality rate than those who do not. The drug prevented the development of new-onset AF and significantly reduced the VR in those with persistent AF.