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Atrial Fibrillation: Rhythm Control or Rate Control?

Am Fam Physician. 2003 Mar 1;67(5):1070.

Typically, management of atrial fibrillation involves pharmacologic or electric maneuvers to convert the patient back to sinus rhythm. Adverse effects from antiarrhythmic drugs and recurrence of fibrillation dilute the benefits of cardioversion. Wyse and colleagues, writing for the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial, compared outcomes in atrial fibrillation with rate control alone and attempted restoration of sinus rhythm.

The investigators sought to enroll patients with atrial fibrillation who also had other cardiovascular risk factors and were deemed more likely to be at risk for long-term recurrence of fibrillation and stroke or death. Of the initial 7,401 patients classified as eligible at screening, 4,060 patients (55 percent) enrolled. The average age of participants was about 70 years. Of the 3,311 patients with echocardiograms, most had a dilated left atrium, but the majority had preserved left ventricular systolic function.

Participants were randomized to rate control alone (via beta blocker, calcium channel blocker, digoxin, or combinations of these drugs) or rhythm control (with antiarrhythmic drugs such as amiodarone or sotalol, used per specified guidelines, and electric cardioversion as necessary). Anticoagulation with warfarin was maintained throughout follow-up in the rate-control group but could be stopped after four to 12 weeks of restored sinus rhythm in the rhythm-control group. Rate control aimed for a resting pulse of no more than 80 beats per minute. The prevalence of sinus rhythm in the rhythm-control group declined from 82.4 percent at one year to 62.6 percent after five years.

After five years of follow-up, there was no significant difference in mortality between the group relying on rate control alone and the group using attempted rhythm control. The rate of stroke (6.3 percent overall) was not different between the two groups, and most events occurred when a patient was not taking warfarin or had a subtherapeutic International Normalized Ratio (INR) of less than 2.0. Rhythm-control patients had a trend toward more hospitalizations (80.1 percent) compared with rate-control subjects (73 percent), and about one third of rhythm-control patients crossed over during the study to rate control because of adverse effects or ineffective antiarrhythmic therapy.

The authors conclude that attempted rhythm control in patients with atrial fibrillation is not associated with a survival benefit or decreased stroke incidence compared with rate control alone and carries higher risks of drug-related adverse effects.

Wyse DG, et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. The Atrial Fibrillation Follow-up Investigation of Rhythm Management Investigators (AFFIRM). N Engl J Med December 5, 2002;347:1825–33, and Van Gelder IC, et al. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med. December 5, 2002;347:1834–40.

editor's note: The same issue of the journal contains a report from a smaller European trial of 522 patients with persistent atrial fibrillation after cardioversion. Each patient received treatment aimed at rate or rhythm control. This study also showed no mortality benefit and no decrease in cardiovascular morbidity when comparing rhythm control with rate control alone. Before consigning rhythm control to obsolescence, however, readers should know that subanalysis of the AFFIRM data for relatively younger patients (younger than 65 years) did show a modest survival benefit. In addition, some fibrillation patients will always merit attempts at rhythm control on symptomatic grounds (e.g., congestive heart failure, decreased exercise tolerance).—b.z.

 

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