Three-Day Magnesium Administration Prevents Atrial Fibrillation After Coronary Artery Bypass Grafting

Background The efficacy of magnesium administration in preventing the occurrence of atrial fibrillation after coronary artery bypass grafting surgery remains controversial. Optimal dose and timing of the administration also await clarification. The purpose of this study was to assess the effect of 3-day postoperative infusion of magnesium on postoperative atrial fibrillation and to find factors that can influence the efficacy of this treatment. Methods After institutional review board approval, a retrospective study was conducted reviewing 200 consecutive patients who underwent isolated, initial coronary artery bypass grafting operation. The first 100 patients did not receive the prophylactic treatment, whereas the next 100 patients were treated with magnesium postoperatively. Patients in the magnesium-treated group received 10 mmol (2.47 g) of magnesium sulfate (MgSO4 • 7H2O) infused daily for 3 days after surgery. Results The incidence of postoperative atrial fibrillation was 35% in the untreated group compared with 16% in the magnesium-treated group (p = 0.002). Multivariate logistic regression analysis revealed that advanced age, decreased left ventricular ejection fraction, and absence of magnesium therapy were independent predictors of postoperative atrial fibrillation. For patients receiving the magnesium therapy, advanced age and decreased ejection fraction were the independent factors that predicted the arrhythmia. Conclusions Postoperative 3-day magnesium infusion is effective in reducing the incidence of atrial fibrillation occurring after coronary artery bypass grafting surgery. However, in older patients or in patients with reduced left ventricular function, magnesium treatment alone is insufficient for prophylaxis of postoperative atrial fibrillation.