Rate Control versus Rhythm Control for Atrial Fibrillation after Cardiac Surgery

Abstract

Background: Atrial fibrillation after cardiac surgery is associated with increased rates of death, complications, and hospitalizations. In patients with postoperative atrial fibrillation who are in stable condition, the best initial treatment strategy--heart-rate control or rhythm control--remains controversial.

Methods: Patients with new-onset postoperative atrial fibrillation were randomly assigned to undergo either rate control or rhythm control. The primary end point was the total number of days of hospitalization within 60 days after randomization, as assessed by the Wilcoxon rank-sum test.

Results: Postoperative atrial fibrillation occurred in 695 of the 2109 patients (33.0%) who were enrolled preoperatively; of these patients, 523 underwent randomization. The total numbers of hospital days in the rate-control group and the rhythm-control group were similar (median, 5.1 days and 5.0 days, respectively; P=0.76). There were no significant between-group differences in the rates of death (P=0.64) or overall serious adverse events (24.8 per 100 patient-months in the rate-control group and 26.4 per 100 patient-months in the rhythm-control group, P=0.61), including thromboembolic and bleeding events. About 25% of the patients in each group deviated from the assigned therapy, mainly because of drug ineffectiveness (in the rate-control group) or amiodarone side effects or adverse drug reactions (in the rhythm-control group). At 60 days, 93.8% of the patients in the rate-control group and 97.9% of those in the rhythm-control group had had a stable heart rhythm without atrial fibrillation for the previous 30 days (P=0.02), and 84.2% and 86.9%, respectively, had been free from atrial fibrillation from discharge to 60 days (P=0.41).

Conclusions: Strategies for rate control and rhythm control to treat postoperative atrial fibrillation were associated with equal numbers of days of hospitalization, similar complication rates, and similarly low rates of persistent atrial fibrillation 60 days after onset. Neither treatment strategy showed a net clinical advantage over the other. (Funded by the National Institutes of Health and the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT02132767.).

Figures

Figure 1. Patients with No Atrial Fibrillation at 7 Days and Status at 30 Days and 60 Days

Panel A shows the proportion of patients undergoing cardiac surgery who had a stable heart rhythm without atrial fibrillation during the first week after randomization in the rate-control group and the rhythm-control group. Panel B shows the status with respect to atrial fibrillation at the time of discharge from the index hospitalization, at 30 days, and at 60 days, according to treatment group. The pink boxes denote patients in atrial fibrillation, and the blue boxes denote patients with a stable heart rhythm without atrial fibrillation. The patients’ status with respect to atrial fibrillation was determined by means of electrocardiography at the time of hospital discharge and at 30 days and 60 days. The accounting for atrial fibrillation included patients who had recurrent atrial fibrillation (as adjudicated by the clinical events committee) or who were readmitted to the hospital for recurrent atrial fibrillation during the interval periods. Overall, 11.5% of patients underwent direct-current cardioversion (9.2% in the rate-control group and 13.8% in the rhythm-control group). Of the direct-current cardioversions, 85% occurred during the index hospitalization. Among the patients who were discharged from the hospital with atrial fibrillation, direct-current cardioversion was performed during the index hospitalization in 3 of 26 patients (12%) in the rate-control group and in 7 of 17 patients (41%) in the rhythm-control group.