Dofetilide: A new antiarrhythmic agent approved for conversion and/or maintenance of atrial fibrillation/atrial flutter

Dofetilide is a new antiarrhythmic agent recently approved for the conversion of and maintenance of sinus rhythm in patients with atrial fibrillation (AF) and atrial flutter (AFI). Dofetilide is a selective class III antiarrhythmic drug which works by selectively blocking the rapid component of the delayed rectifier outward potassium current (I_kr). Dofetilide has been shown to prolong the effective refractory period which is accompanied by a dose-dependent prolongation of the QT and QTc intervals, with parallel increases in ventricular refractoriness. Approximately 80% of dofetilide is excreted in the urine which requires dose adjustments in renal insufficiency. The elimination half-life is approximately 10 h in patients with normal renal function. The therapeutic blood level range of dofetilide is presently unknown and monitoring of dofetilide blood levels is not available at this time. Clinical trials have shown dofetilide to be superior to flecainide in converting AFI patients to normal sinus rhythm (NSR) (70% vs. 9%; p