Does flecainide regain its antiarrhythmic activity after electrical cardioversion of persistent atrial fibrillation?

OBJECTIVES: The purpose of this study was to evaluate the hypothesis that presumed reversion of electrical remodeling after cardioversion of atrial fibrillation (AF) restores the efficacy of flecainide. BACKGROUND: Flecainide loses its efficacy to cardiovert when AF has been present for more than 24 hours. Most probably, the loss is caused by atrial electrical remodeling. Studies suggest electrical remodeling is completely reversible within 4 days after restoration of sinus rhythm (SR). METHODS: One hundred eighty-one patients with persistent AF (median duration 3 months) were included in this prospective study. After failure of pharmacologic cardioversion by flecainide 2 mg/kg IV (maximum 150 mg in 10 minutes) and subsequent successful electrical cardioversion, we performed intense transtelephonic rhythm monitoring three times daily for 1 month. In case of AF recurrence, a second cardioversion by flecainide was attempted as soon as possible. RESULTS: AF recurred in 123 patients (68%). Successful cardioversion by flecainide occurred only when SR had been maintained for more than 4 days (7/51 patients [14%]). Failure to cardiovert was associated with a prolonged duration of the recurrent AF episode and concurrent digoxin use. Multivariate logistic regression confirmed that successful cardioversion was determined by digoxin use (odds ratio [OR] 0.093, P = .047) and by the interaction between the duration of SR and the (inverse) duration of recurrent AF (OR 6.499, P < .001). When flecainide was administered within 10 hours after AF onset and the duration of SR was greater than 4 days, the success rate was 58%. CONCLUSIONS: Flecainide recovers its antiarrhythmic action after cardioversion of AF. However, successful pharmacologic cardioversion occurs only after SR has lasted at least 4 days and is expected only for recurrences having duration of a few hours. Immediate pharmacologic cardioversion of AF recurrence may be a worthwhile strategy for management of persistent AF.

Beta-blockers prevent subacute recurrences of persistent atrial fibrillation only in patients with hypertension.

AIM: Differential drug treatment guided by the underlying heart disease may improve outcome of rhythm control therapy. In the present study we investigated in a well-defined group with either lone atrial fibrillation (AF) or hypertension whether there were differences in rhythm control outcome between both groups in relation to the use of cardiovascular drugs. METHODS AND RESULTS: One hundred sixty-two patients were included after successful cardioversion of persistent AF. None of the patients was given a class I or III antiarrhythmic drug. Patients' heart rhythm was checked 3 times a day, using transtelephonic monitoring for 1 month after cardioversion. One month after cardioversion up to 68% of patients had a recurrence of persistent AF. During the first 3 days almost no recurrences were seen on beta-blocker therapy whereas recurrences peaked on day 2-3 in the absence of beta-blockers. Univariate analysis showed that the use of beta-adrenergic receptor blockers and the presence of hypertension were associated with a lower recurrence rate at 1 month. Multivariate logistic regression analysis demonstrated that beta-blockade was the only statistically significant parameter predicting sinus rhythm at 1 month (OR 0.40, 95% CI 0.19-0.86, P=0.02). CONCLUSIONS: Compared with lone AF patients, patients in the setting of hypertension maintain sinus rhythm much better after cardioversion when treated with a beta-blocker. Beta-blockade protects, in particular, against the early subacute recurrences. These findings underscore the importance of a differential approach towards drug prevention of post-cardioversion recurrences depending on the underlying heart disease.

A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation.

BACKGROUND: Maintenance of sinus rhythm is the main therapeutic goal in patients with atrial fibrillation. However, recurrences of atrial fibrillation and side effects of antiarrhythmic drugs offset the benefits of sinus rhythm. We hypothesized that ventricular rate control is not inferior to the maintenance of sinus rhythm for the treatment of atrial fibrillation. METHODS: We randomly assigned 522 patients who had persistent atrial fibrillation after a previous electrical cardioversion to receive treatment aimed at rate control or rhythm control. Patients in the rate-control group received oral anticoagulant drugs and rate-slowing medication. Patients in the rhythm-control group underwent serial cardioversions and received antiarrhythmic drugs and oral anticoagulant drugs. The end point was a composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, implantation of a pacemaker, and severe adverse effects of drugs. RESULTS: After a mean (+/-SD) of 2.3+/-0.6 years, 39 percent of the 266 patients in the rhythm-control group had sinus rhythm, as compared with 10 percent of the 256 patients in the rate-control group. The primary end point occurred in 44 patients (17.2 percent) in the rate-control group and in 60 (22.6 percent) in the rhythm-control group. The 90 percent (two-sided) upper boundary of the absolute difference in the primary end point was 0.4 percent (the prespecified criterion for noninferiority was 10 percent or less). The distribution of the various components of the primary end point was similar in the rate-control and rhythm-control groups. CONCLUSIONS: Rate control is not inferior to rhythm control for the prevention of death and morbidity from cardiovascular causes and may be appropriate therapy in patients with a recurrence of persistent atrial fibrillation after electrical cardioversion.