title: Intraoperative Magnesium Administration Does Not Reduce Postoperative Atrial Fibrillation After Cardiac Surgery.
abstract: BACKGROUND
  Hypomagnesemia has been associated with an increased risk of postoperative atrial fibrillation (POAF). Although previous studies have suggested a beneficial effect of magnesium (Mg) therapy, almost all of these are limited by small sample size and relatively low Mg dose. We hypothesized that high-dose Mg decreases the occurrence of new-onset POAF, and we tested this hypothesis by using data from a prospective trial that assessed the effect of Mg on cognitive outcomes in patients undergoing cardiac surgery.
  
  
  METHODS
  A total of 389 patients undergoing cardiac surgery were enrolled in this double-blind, placebo-controlled trial. Subjects were randomized to receive Mg as a 50-mg/kg bolus immediately after induction of anesthesia followed by another 50 mg/kg as an infusion given over 3 hours (total dose, 100 mg/kg) or placebo. We tested the effect of Mg therapy on POAF with logistic regression, adjusting for the risk of atrial fibrillation (AF) by using the Multicenter Study of Perioperative Ischemia risk index for Atrial Fibrillation after Cardiac Surgery.
  
  
  RESULTS
  Among the 363 patients analyzed, after we excluded patients with chronic or acute preoperative AF (placebo: n = 177; Mg: n = 186), the incidence of new-onset POAF was 42.5% (95% confidence interval [CI], 35%-50%) in the Mg group compared with 37.9% (95% CI, 31%-45%) in the placebo group (P = 0.40). The 95% CI for this absolute risk difference of 4.6% is -5.5% to 14.7%. The time to onset of POAF also was identical between the groups, and no significant effect of Mg was found in logistic regression analysis after we adjusted for AF risk (odds ratio, 1.09; 95% CI, 0.69-1.72; P = 0.73).
  
  
  CONCLUSIONS
  High-dose intraoperative Mg therapy did not decrease the incidence of new-onset POAF after cardiac surgery.
authors.affiliation: From the Departments of Anesthesiology, Medicine-Cardiology, and Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Rebecca Y
authors.initials: RY
authors.lastname: Klinger
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Thunberg
authors.forename: William D
authors.initials: WD
authors.lastname: White
authors.forename: Manuel
authors.initials: M
authors.lastname: Fontes
authors.forename: Nathan H
authors.initials: NH
authors.lastname: Waldron
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Piccini
authors.forename: G Chad
authors.initials: GC
authors.lastname: Hughes
authors.forename: Mihai V
authors.initials: MV
authors.lastname: Podgoreanu
authors.forename: Mark
authors.initials: M
authors.lastname: Stafford-Smith
authors.forename: Mark F
authors.initials: MF
authors.lastname: Newman
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Mathew
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000639:trends; D015331:Cohort Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007430:Intraoperative Care / Q000379:methods*; D008274:Magnesium / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D011446:Prospective Studies
chemical_list: D008274:Magnesium