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A New Treatment for Atrial Fibrillation on the Horizon?

Dronedarone, an agent similar to — but potentially less toxic than — amiodarone, shows some promise in a placebo-controlled trial.

Atrial fibrillation is the most common arrhythmia in most countries and is expected to grow in prevalence as longevity increases. Treatment of AF is targeted at reducing fatigue and increasing exercise tolerance, which require maintenance of sinus rhythm, and at reducing the risk for stroke. However, amiodarone, the antiarrhythmic agent most efficacious in AF, is associated with potentially serious adverse events. In two identically designed, manufacturer-funded, international, prospective trials (one in Europe; the other in the U.S., Canada, Australia, South Africa, and Argentina), investigators compared dronedarone, an agent derived from amiodarone but believed to have fewer adverse effects, with placebo in individuals with AF and without heart failure.

A total of 828 patients received dronedarone, and 409 received placebo. Compared with placebo, dronedarone significantly increased the median time to first recurrence of AF and reduced mean heart rate and reappearance of symptoms during AF recurrence. At 1 year of follow-up, the risk for AF recurrence in the European arm of the study was 67% with dronedarone, compared with 77% with placebo; in the non-European arm, the risk for AF recurrence was 61% with dronedarone, compared with 73% with placebo. Substantial evidence of toxicity was rare among all participants in this short-term trial.

Comment: The treatment of atrial fibrillation continues to bedevil physicians and patients alike, so a more effective pharmacologic agent would be heartily welcomed. Whether dronedarone will fulfill its promise in this regard remains to be proven, both by longer-term trials to ensure that significant toxicity is absent and by direct comparison with amiodarone.

— Mark S. Link, MD

Published in Journal Watch Cardiology September 5, 2007

Citation(s):

Singh BN et al. for the EURIDIS and ADONIS Investigators. Dronedarone for maintenance of sinus rhythm in atrial fibrillation or flutter. N Engl J Med 2007 Sep 6; 357:987-99.

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• Medline abstract (Free)

Ezekowitz MD. Maintaining sinus rhythm — making treatment better than the disease. N Engl J Med 2007 Sep 6; 357:1039-41.

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• Medline abstract (Free)