The efficacy of supplemental magnesium in reducing atrial fibrillation after coronary artery bypass grafting.
BACKGROUND
Atrial fibrillation after coronary artery bypass is reported from 17% to 53%. Hypomagnesemia after this surgery is considered a contributing factor.


METHODS
Two hundred-two coronary bypass patients were randomized to magnesium (n = 105) or placebo (n = 97). The experimental group received 80-mg magnesium sulfate per kilogram ideal weight in 100 mL dextrose 5% water 30 minutes preoperatively. Postoperatively, patients received 8-mg magnesium sulfate per kilogram ideal weight intravenous per hour more than 48 hours. The control group received dextrose 5% water at these intervals.


RESULTS
After the first bolus serum magnesium was experimental 4.75 mg/dL versus control 1.91 mg/dL, p less than 0.001, and remained different until postoperative day 4 (experimental 2.33 mg/dL vs control 2.26 mg/dL, p = 0.24). Atrial appendage and strap muscle were analyzed after the first bolus and after revascularization. There were no differences between groups in tissue magnesium or calcium. Urinary magnesium was elevated in the experimental (experimental 324.5 mg/24 hours, vs control 45.1 mg/24 hours, p = 0.01). Calcium excretion was higher (experimental 370 mg/24 hours vs control 186 mg/24 hours, p < 0.001) and was associated with lower serum calcium. Serum calcium was higher in the control through the fourth postoperative day. The incidence of atrial fibrillation was experimental 32 of 105 (30.5%) versus control 41 of 97 (42.3%) p = 0.08. Atrial fibrillation was different on the first postoperative day (experimental 3/105, 2.9% vs control 9/97, 9.3%), p = 0.05.


CONCLUSIONS
Overall prophylactic magnesium supplementation does not significantly reduce atrial and ventricular arrhythmias. The only significant benefit of magnesium supplementation was on the first postoperative day.
Southern Illinois University School of Medicine, Springfield, IL, USA. shazelrigg@siumed.edu
Stephen R
SR
Hazelrigg
Theresa M
TM
Boley
Ibrahim B
IB
Cetindag
Kreigh P
KP
Moulton
Gary L
GL
Trammell
Joan E
JE
Polancic
Tilitha S
TS
Shawgo
Jacquelyn A
JA
Quin
Stephen
S
Verhulst
D001281:Atrial Fibrillation / Q000517:prevention & control*; D002118:Calcium / Q000032:analysis; D001026:Coronary Artery Bypass; D005260:Female; D006325:Heart Atria / Q000737:chemistry; D006801:Humans; D007275:Injections, Intravenous; D008274:Magnesium / Q000032:analysis; D008278:Magnesium Sulfate / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011183:Postoperative Complications / Q000517:prevention & control
D008278:Magnesium Sulfate; D008274:Magnesium; D002118:Calcium