Dose-response relations of azimilide in the management of symptomatic, recurrent, atrial fibrillation. We evaluated the efficacy and safety of azimilide, a new class III antiarrhythmic agent that blocks both the slow and fast components of the cardiac-delayed rectifier potassium currents in 4 randomized, double-blind, placebo-controlled trials with similar protocols. The purpose of this study was to assess the relation between dose and effect. A total of 1,380 patients with a documented history of symptomatic atrial fibrillation (AF), atrial flutter, or both, were enrolled. After a 3-day loading period during which the assigned dose was given twice a day, subjects received placebo or azimilide (35, 50, 75, 100, or 125 mg once a day) for the duration of the study period. The primary end point