Ibutilide for cardioversion of atrial flutter: efficacy of a single dose in recent-onset arrhythmias

Ibutilide is particularly effective in rapid termination of atrial flutter (AFL) with few adverse effects. Despite the recommendation of 2 infusions, cardioversion may occur up to 70 minutes after a single dose. We investigated the feasibility, efficacy and safety of a single dose ibutilide treatment of AFL in a single-center, observational study.

Fifty-nine consecutive patients (44 males, mean age 70 +/- 12), referred to our CCU for paroxysmal AFL (mean arrhythmia duration 10 +/- 18 days), were treated with 1 mg ibutilide. In case of inefficacy, a 2nd dose could be administered 10 to 60 minutes later on the basis of the ECG examination for QTc prolongation and AFL cycle variations. Successful cardioversion was defined as sinus rhythm (SR) restoration within 2 hours.

Forty-four patients (75%) converted to SR after ibutilide, 31 with single dose (53%, Group 1), and 13 with double dose (22%, Group 2). AFL duration was shorter in Group 1 (4 +/- 5 vs 16 +/- 29 days). The mean time to the 2nd dose administration was 34 +/- 11 minutes in responders, 51 +/- 23 minutes in non-responders. Only 3 (5%) significant adverse events, all observed after a single dose, occurred.

Ibutilide is highly effective and safe, in a monitored environment, for rapid termination of AFL. Recent onset AFL may be terminated with a single infusion in many cases; yet, cardioversion should be waited for no more than 30 minutes after the end of the 1st dose, before administering the 2nd one, in order not to reduce the possibility of SR restoration.