293 CLINICAL REVIEW Intravenous Magnesium for Prevention of Atrial Fibrillation After Coronary Artery Bypass Surgery: A Systematic Review and Meta-Analysis Abdullah A. Alghamdi, M.D., Osman O. Al-Radi, M.D., M.Sc., and David A. Latter, M.D., F.R.C.S.C. Division of Cardiac Surgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada ABSTRACT Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass surgery. The objective of this study was to assess the effectiveness of intravenous magnesium in pre- venting postoperative atrial fibrillation. A meta-analysis of eight identified randomized controlled trials, reporting comparisons between magnesium and control was undertaken. The primary outcome was in- cidence of postoperative atrial fibrillation. Our review revealed that use of intravenous magnesium is associated with a significant reduction in the incidence of atrial fibrillation after coronary artery bypass surgery, with a relative risk of 0.64 (95% confidence interval = 0.47, 0.87, and p = 0.004). doi: 10.1111/j.1540- 8191.2005.200447.x (J Card Surg 2005;20:293-299) Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass grafting surgery (CABG). Its incidence ranges from 25% to 40%. 1-7 Atrial fibrillation after CABG is an important source of morbidity. It is associated with an increased risk of thromboembolic complications, hemodynamic compromise—especially in those with poor ventricular function—and with longer hospital stay with a consecu- tive increase in the cost of care. 5,8-14 Therefore, primary prevention is of great importance. Although the cause of atrial fibrillation after CABG is not clear, it is thought to be multifactorial; advanced age, previous history of atrial fibrillation, and low mag- nesium levels are risk factors. 13-15 Various pharmacological agents have been used to treat or prevent AF after CABG. Several clinical tri- als have evaluated the use of magnesium sulfate to prevent AF after CABG. 16-31 These trials have ad- vocated conflicting recommendations. There are no systematic reviews to date focusing on the use of magnesium sulfate as a prophylactic measure to pre- vent AF after CABG. The objective of this study was to assess the effectiveness of perioperative in- travenous magnesium sulfate in preventing AF after CABG. Address for correspondence: A. A. Alghamdi, M.D., Department of Cardiac Surgery, Toronto General Hospital, EN 14-215, 200 Elizabeth Street. Toronto, ON M5G 2C4 Canada. Fax: (416) 864-6067; e-mail: abdullah.alghamdi@utoronto.ca MATERIALS AND METHODS Inclusion and exclusion criteria All published randomized, controlled clinical trials that included adults (age above 18) undergoing elec- tive CABG (defined as isolated coronary revasculariza- tion operation that does not need to be performed at the same hospital admission) were included. Both on- pump and off-pump CABG techniques were included and no limitations were applied to the number of the grafts used or the conduit types. The intervention was magnesium sulfate, as a bolus or continuous infusion, of a specified dose and duration, given as a prophylac- tic measure (before the onset of AF) in the intervention group, and placebo or no intervention in the control group. The primary outcome was the incidence of AF after CABG (defined as totally irregular atrial rhythm leading to irregular ventricular rhythm, measured using a continuous electrocardiogram (ECG) and confirmed by standard 12-lead ECG). Studies that met any one of the following criteria were excluded: unspecified methods of detection of AF or unspecified period of follow-up, participants with chronic or paroxysmal AF, and participants with history of arrhythmias (any rhythm other than normal sinus rhythm). Literature search and data extraction Studies were identified by searching MEDLINE, EMBASE, and the Cochrane Controlled Trial Register