Intravenous metoprolol versus biatrial pacing in the prevention of atrial fibrillation after coronary artery bypass surgery: a prospective randomized open trial.

Background and Aims: Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass surgery (CABG). Intravenous metoprolol and biatrial pacing have been reported to be effective in AF prophylaxis after cardiac surgery. The purpose of this trial was to compare the efficacy of intravenous metoprolol versus biatrial pacing combined with oral metoprolol in the prevention of AF after CABG. Methods: A single-centre prospective randomized open trial of 165 consecutive patients undergoing their first CABG. Patients were randomized to receive either intravenous metoprolol infusion 1-3 mg per hour or biatrial overdrive pacing and oral metoprolol (50-150mg) daily for 72 hours after CABG starting immediately after the surgery. AAI pacing with a pacing rate of 10 beats/minute above the baseline heart rate was used. Patients had continuous ECG-monitoring. The primary end point was the first episode of AF. Results: The incidence of postoperative AF in the intravenous metoprolol and biatrial pacing groups did not differ from each other (14% vs. 18% respectively, p = 0.66). There was no difference in the time of AF onset between the groups (28.2 16.2 h vs. 30.1 +/- 21.2 h respectively, p = 0.8). Intravenous metoprolol infusion had to be temporarily interrupted for one hour in eleven patients because of hypotension or bradycardia. One case of bleeding from the left atria related to the pacemaker electrode wire was found. Conclusion: We found no difference in the incidence of AF between patients treated with intravenous metoprolol or the combination of biatrial pacing and oral metoprolol.