Randomized study of early intravenous esmolol versus oral beta-blockers in preventing post-CABG atrial fibrillation in high risk patients identified by signal-averaged ECG: Results of a pilot study

Background: Patients with prolonged signal-averaged ECG have four times higher risk for development of atrial fibrillation (AF) after coronary artery bypass surgery (CABG). Incidence of AF is reduced, but not eliminated by prophylaxis with beta-blockers. The limitations of prophylaxis with oral beta-blockers may be related to the delayed effect of oral therapy. We performed a pilot study of the efficacy of early intravenous esmolol and an oral beta-blocker regimen for prevention of postoperative AF. Methods: Fifty patients referred for CABG and considered to be at high risk for postoperative AF on the basis of prolonged signal-averaged ECC P wave duration > 140 ms were randomized to receive either a 24-hour infusion of esmolol 6-18 hours after CABC, at an average dose 67 +/- 7 mug/kg/min, followed by oral beta-blockers versus oral beta-blockers only beginning on postoperative day 1. Results: Seven of 27 patients (26%) in the esmolol group and 6 of 23 patients (26%) in the oral beta-blocker group developed postoperative AF, P = NS. The mean time of onset of AF (2.7 +/- 0.5 vs 2.7 +/- 0.3 postoperative day, P = NS) and the median duration of AF (10 [2192] vs 7 [1.16] hours, P = NS) were similar between the two groups. Eleven (41%) patients treated with esmolol developed adverse events (hypotension: 8, bradycardia requiring temporary pacing: 2, left ventricular failure:1 patient) as compared to only one patient (4%) in the beta-blocker group who developed hypotension, P = 0.006. Conclusions: This randomized controlled pilot study suggests that intravenous esmolol is less well tolerated and offers no advantages to standard beta-blocker in preventing AF after CABC.