Chemical cardioversion of atrial fibrillation with intravenous dofetilide

We studied the effects of two active dose levels of dofetilide (8 and 12 micrograms/kg) and placebo in 16 patients with recent onset atrial fibrillation. The study was of a crossover design such that all patients received a therapeutic agent, 15 patients completed the study. Cardioversion was achieved in 2/6 patients receiving 8 micrograms/kg dofetilide and in 2/9 patients receiving 12 micrograms/kg. No patients cardioverted as a result of the placebo infusion. Two patients who cardioverted suffered episodes of torsades de pointes following the active drug. Electrical cardioversion was attempted in eight patients who remained in atrial fibrillation and was successful in six. The average duration of atrial fibrillation was 35 days in those who cardioverted and 83 days in those who did not. The compound appears to have only limited effect in cardioversion of atrial fibrillation of moderate duration.