Intravenous plus oral amiodarone, atrial septal pacing, or both strategies to prevent post-cardiothoracic surgery atrial fibrillation: the Atrial Fibrillation Suppression Trial II (AFIST II).

Background: The effect of a hybrid intravenous and oral prophylactic amiodarone regimen on postcardiothoracic surgery (CTS) atrial fibrillation (AF) is unknown. The impact of active atrial septal pacing on post-CTS AF has not been well characterized. In addition, the effect of using both amiodarone and atrial septal pacing together to prevent atrial fibrillation is unknown.

Methods And Results: Patients (n=160) were randomized to amiodarone or placebo and then to pacing or no pacing using a 2x2 factorial design. All therapies began within 6 hours post-CTS. Amiodarone was given by intravenous infusion for the first 24 hours (1050 mg total) followed by oral therapy for 4 postoperative days (4800 mg total). Atrial septal pacing was given for 96 hours. Amiodarone reduced the risk of AF by 43% and the risk of symptomatic AF by 68% (P=0.037 and P=0.019) versus placebo. Atrial septal pacing did not reduce AF or symptomatic AF incidence versus no pacing. The risk of post-CTS AF in the patients receiving amiodarone+pacing was lower than the placebo+no pacing and the placebo+pacing groups (57.9% and 60.5% reductions, P=0.047 and P=0.040, respectively).

Conclusions: Amiodarone given as both an intravenous and oral regimen is effective at reducing post-CTS AF but atrial septal pacing is ineffective. Combining amiodarone and pacing is better than placebo with or without pacing but not amiodarone alone.