INTRAVENOUS DOFETILIDE, A CLASS-III ANTIARRHYTHMIC AGENT, FOR THE TERMINATION OF SUSTAINED ATRIAL-FIBRILLATION OR FLUTTER

Objectives. This study sought to determine the safety and efficacy of a single bolus of intravenous dofetilide, a pure class III antiarrhyth mic agent, for the termination of sustained atrial fibrillation or flu tter. Background. Dofetilide is a highly selective blocker of the rapi d component of the delayed rectifier current causing action potential prolongation, These effects, and preliminary clinical data, suggest th at it may be effective in the treatment of atrial fibrillation and flu tter. Methods. Ninety-one patients with sustained atrial fibrillation (75 patients) or flutter (16 patients) were entered into a double blin d, randomized multicenter study of one of two doses of dofetilide (4 o r 8 mu g/kg body weight) or placebo. Results. Dofetilide effectively t erminated the arrhythmia in 31% of patients receiving 8 mu g/kg, a sta tistically significant difference from those receiving 4 mu g/kg (conv ersion rate 12.5%, p < 0.05) or placebo ino conversion, p < 0.01), Pat ients with atrial Butter had a greater response to dofetilide (54% con version rate) than those with atrial fibrillation (14.5% conversion ra te, p < 0.001). Conclusions. Intravenous dofetilide can convert sustai ned atrial fibrillation or flutter to sinus rhythm, However, its effic acy is greater in flutter-a response that contrasts with the poorer re sponse seen with class I agents, This finding potentially represents a n important advance in the pharmacologic termination of atrial flutter . (C) 1997 by the American College of Cardiology.