Patient Preference Should Guide Postoperative AF Strategy

Rate control and rhythm control are equivalent as initial strategies for management of postoperative atrial fibrillation (AF) in terms of total number of hospital days and the rate of complications within 60 days of randomization to either strategy. So conclude the authors of a large open-label study conducted by the Cardiothoracic Surgical Trials Network (CTSN).

Because the two strategies have differing toxicities, levels of tolerance and time to resolution of AF, choice of strategy should be driven largely by physician and patient preference, according to A. Marc Gillinov, MD, who presented the study findings April 4 at ACC.16, the American College of Cardiology’s 65th Annual Scientific Session. The findings were simultaneously published by the New England Journal of Medicine.

“Data on the management of postoperative AF in the cardiac surgical setting have been sparse,” says Dr. Gillinov, a cardiothoracic surgeon at Cleveland Clinic, which serves as one of the CTSN’s core clinical centers. “The CTSN trial randomized 10 times as many patients as the previous lone randomized trial comparing rate control to rhythm control, and therefore offers important insights into the efficacy and trade-offs between these two management strategies.”

Enduring uncertainty around rate vs. rhythm control

The incidence of AF after cardiac surgery is estimated to be 20 to 50 percent, and postoperative AF is associated with excess morbidity and long-term mortality as well more frequent hospitalizations and increased healthcare costs.

Retrospective studies of patients with postoperative AF that compared rhythm control using antiarrhythmic drugs and/or direct-current (DC) cardioversion versus rate control have suggested possible advantages with rhythm control, but the data have not been conclusive. This lack of definitive evidence has led to major practice variations in AF management following cardiac surgery.

Against this backdrop, CTSN investigators decided to tackle the question by randomizing 523 hemodynamically stable patients with AF following elective cardiac strategy to rate control or rhythm control.

Essentials of the study design

In the group assigned to rate control, medications including beta-blockers, calcium channel blockers and digoxin were used to achieve a resting heart rate of less than 100 beats per minute. Patients in this arm could be switched to rhythm control if sinus rhythm could not be achieved.

The rhythm control arm was treated with amiodarone with or without a rate-slowing agent. If AF persisted for up to 48 hours after randomization, DC cardioversion was recommended.

Anticoagulation with warfarin was indicated when patients remained in AF or had recurrent AF during their index hospitalization.

Results show no clear superiority

On the study’s primary end point — total number of hospital days within 60 days of randomization — there was no significant difference between the rate control arm (mean of 6.4 days, median of 5.1 days) and the rhythm control arm (mean of 7.0 days, median of 5.0 days) (P = .76).

“We chose this end point because it captures the short-term impact of a diverse set of adverse events,” Dr. Gillinov explains.

The groups were also highly comparable in numerous secondary end points, including mortality at 60 days, overall serious adverse events, length of stay during index hospitalization, and share of patients discharged with stable, non-AF rhythm. At 60 days after randomization, however, a modestly but significantly greater percentage of patients were in stable, non-AF rhythm in the rhythm control arm (96.6 percent) relative to the rate control arm (92.3 percent) (P = .02)

Similar proportions of patients were unable to adhere to assigned therapy, with 23.8 percent of those in the rhythm control arm not completing the full course of amiodarone and switching to rate control and 25.6 percent of those in the rate control arm also receiving amiodarone or DC cardioversion. Deviation from assigned therapy was primarily for drug ineffectiveness in the rate control group and for amiodarone toxicity or intolerance in the rhythm control group.

More patients in the rate control arm met protocol-specified indications for anticoagulation (46.2 percent, vs. 31.8 percent with rhythm control), but comparable proportions in the two groups were prescribed warfarin at discharge, and average time on anticoagulation was highly similar.

The lead author’s perspective

“While much of the toxicity and intolerance associated with amiodarone can be avoided with rate control, resolution of AF is slightly slower with the latter strategy,” Dr. Gillinov notes. “It is reasonable to begin with a strategy of rate control to manage postoperative AF.”

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