Is pretreatment with ibutilide useful for atrial fibrillation cardioversion when combined with biphasic shock?

Cardioversion of atrial fibrillation by means of a monophasic transthoracic shock is facilitated by pretreatment with ibutilide. The aim of this study was to randomly and prospectively compare the energy requirements of transthoracic biphasic cardioversion of atrial fibrillation with and without ibutilide pretreatment.

Fifty patients were enrolled and randomized into two groups: immediate cardioversion with biphasic shock (group 1) or ibutilide pretreatment followed by cardioversion with biphasic shock (group 2). In group 2, ibutilide was administered intravenously in 10 min at a dose of 0.01 mg/kg. A pause of 10 min was observed before the patients underwent cardioversion.

All patients of both groups were successfully cardioverted (100%). Energy and number of shocks were significantly lower in group 2 than in group 1 (P< 0.02). Eleven of 25 patients (44%) in group 1 and 15 of 23 patients (65%) in group 2 were cardioverted at the first attempt with 50 J. The number of patients cardioverted at the first attempt with 50 J was significantly higher in group 2 than in group 1 (P = 0.018).

Although not essential for a successful outcome, pretreatment with ibutilide can lower energy requirements in transthoracic biphasic cardioversion.