NEJM: Rate control preferred over rhythm control for treating a-fib patients

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In patients with atrial fibrillation and congestive heart failure, a routine strategy of rhythm control does not reduce the rate of death from cardiovascular causes, as compared with a rate-control strategy, according to a randomized controlled study published in the June 19 issue of the New England Journal of Medicine.

Denis Roy, MD, from the Montreal Heart Institute and the Université de Montréal in Montreal, and colleagues wrote that it is common practice to restore and maintain sinus rhythm in patients with atrial fibrillation and heart failure. The approach is based in part on data indicating that atrial fibrillation (AF) is a predictor of death in patients with heart failure and suggesting that the suppression of AF may favorably affect the outcome. However, the researchers said that benefits and risks of the approach have not been adequately studied.

The researchers conducted a multicenter, randomized trial comparing the maintenance of sinus rhythm (rhythm control) with control of the ventricular rate (rate control) in patients with a left ventricular ejection fraction of 35 percent or less, symptoms of congestive heart failure, and a history of AF in the Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial.

The authors wrote that their primary outcome was the time to death from cardiovascular (CV) causes.

A total of 1,376 patients were enrolled (682 in the rhythm-control group and 694 in the rate-control group) and were followed for a mean of 37 months, the investigators said.

The researchers found that of the nearly 1,400 patients, 182 (27 percent) in the rhythm-control group died from CV causes, as compared with 175 (25 percent) in the rate-control group.

Roy and colleagues found that the secondary outcomes were similar in the two groups, including death from any cause (32 percent in the rhythm-control group and 33 percent in the rate-control group), stroke (3 and 4 percent, respectively), worsening heart failure (28 and 31 percent), and the composite of death from CV causes, stroke or worsening heart failure (43 and 46 percent). There were also no significant differences favoring either strategy in any predefined subgroup.

The authors noted the study population is representative of an international population of patients with AF and congestive heart failure, and compliance with the assigned therapeutic strategy was high, and 75 to 80 percent of patients in the rhythm-control group were in sinus rhythm at repeated assessments during a relatively long follow-up period (three years on average).

The rhythm-control strategies used in the AF-CHF trial and the other cited studies do not guarantee the maintenance of sinus rhythm, and not all patients in the rate-control group had persistent AF, Michael E. Cain, MD, from the School of Medicine and Biomedical Sciences, University at Buffalo in N.Y., and Anne B. Curtis, MD, from the University of South Florida in Tampa, Fla., wrote in an accompanying NEJM editorial. 

Cain and Curtis also noted that the “toxicity of antiarrhythmic drugs probably contributed to the lack of benefit observed in the rhythm-control group.”

Also, both AF-CHF trial and the editorial noted that AF may be a marker of poor prognosis, in which the primary problem is poor ventricular function, neurohormonal activation or inflammation, with no independent effect of AF on outcome.
Cain and Curtis recommended that investigators should next focus on a rhythm-control strategy that eliminates the confounding contributions of low efficacy and high toxicity associated with antiarrhythmic drug therapy to better determine the desirability of maintaining sinus rhythm in patients with AF.