Maintenance of sinus rhythm in patients with atrial fibrillation: An AFFIRM substudy of the first antiarrhythmic drug

OBJECTIVES: This study evaluated the efficacy of antiarrhythmic drugs for the treatment of atrial fibrillation (AF). BACKGROUND: The most effective and safest antiarrhythmic drug for the treatment of AF is unknown. METHODS: The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study compared two treatment strategies - rate control and rhythm control - in patients with AF and risk factors for stroke or death. This substudy, performed in patients randomized to rhythm control, compared different antiarrhythmic drugs by randomly assigning the first drug treatment to: 1) amiodarone, 2) sotalol, or 3) a class I drug. The primary end point was the proportion of patients alive, in sinus rhythm, with no additional cardioversions and still taking the assigned drug at one year. Comparisons were made between patients eligible for each of three drug pairs. RESULTS: At one year, in 222 patients randomized between amiodarone and class I agents, 62% were successfully treated with amiodarone, compared with 23% taking class I agents (p < 0.001). In 256 patients randomized between amiodarone and sotalol, 60% versus 38% were successfully treated, respectively (p = 0.002). In 183 patients randomized between sotalol and class I agents, 34% versus 23% were successfully treated, respectively (p = 0.488), although this portion of the substudy was stopped early when amiodarone was shown to be better than class I agents. Sinus rhythm was achieved in nearly 80% of patients at one-year follow-up with serial therapy. Adverse effects were common. CONCLUSIONS: Amiodarone was more effective at one year than either sotalol or class I agents for the strategy of maintenance of sinus rhythm without cardioversion.