Effect of prophylactic bisoprolol plus magnesium on the incidence of atrial fibrillation after coronary bypass surgery:: results of a randomized controlled trial

Objective: Bisoprolol, a highly cardioselective beta(1)-blocker, is widely used to treat elderly patients with hypertension, coronary artery disease and heart failure. The current literature lacks evidence regarding its potency to prevent atrial fibrillation (AF) following cardiac surgery. Therefore the aim of this study was to evaluate the efficacy of bisoprolol plus magnesium (Mg) in the prophylaxis of AF after coronary artery bypass graft (CABG) surgery. Research design and methods: A total of 100 consecutive patients subjected to elective on-pump CABG (84 men, age 65 +/- 8 [SD] years), with no prior AF history, were randomly assigned to the prophylaxis group (n = 50) receiving after surgery bisoprolol (5 mg/day) plus Mg (intravenous infusion of 2 g of Mg on arrival in the intensive care unit, followed by oral Mg at 1800 mg/day for 1 week), or to the control group (n = 50), receiving no combined study medication but remaining on their preoperative drugs, including beta-blockers. All patients were continuously monitored to identify the onset of AF. Results: In the prophylaxis group the incidence of postoperative AF was significantly lower, with 20% (10/50) compared to 42% (21/50) among controls (p = 0.030, 95% confidence interval [CI] for absolute risk reduction [ARR], 2-42%). Particularly in the elderly, bisoprolol plus Mg was effective in preventing AF; in the prophylaxis group only six of 36 (17%) patients = 65 years of age developed AF, compared to 13 of 20 (65%) in the control group (p < 0.001, 95% CI for ARR, 17 - 65%). This was associated with significantly (p = 0.022) shorter hospital stays in the prophylaxis group (median of 7 vs. 9 days, 95% CI for difference in medians, 0 - 3 days). Conclusions: The combination of bisoprolol plus Mg effectively reduces the incidence of postoperative AF following on-pump CABG, particularly in elderly patients, and is associated with a shorter hospital length of stay.