Randomised trial on the influence of continuous magnesium infusion on arrhythmias following cardiopulmonary bypass surgery for congenital heart disease

Objectives. To check the hypothesis that continuous magnesium infusion protects the heart from arrhythmias following cardiopulmonary bypass surgery for congenital heart disease. Design. A prospective randomised placebo-controlled study, with patients stratified in three weight groups. Patients and participants. The study group (n=65) postoperatively received a magnesium infusion (1 mmol/kg), the control group (n=66) received placebo. In both groups serum and ionised magnesium values were followed, and all postoperative arrhythmias were documented for 24 h. Measurements and results. Serum and ionised magnesium in the blood was elevated after the end of bypass (0.54+/-0.15 mmol l(-1) pre-operatively, 0.88+/-0.24 mmol l(-1) postoperatively), where a cardioplegia solution containing magnesium was used. Magnesium values remained at this elevated level in the magnesium therapy group, and decreased to normal pre-operative values within 24 h in controls (P<0.001). The incidence of postoperative arrhythmias was lower in the study group: 8/65 in the study group and 17/66 in the control group, respectively (chi-squared test, P=0.05). Lower patient weight (32.7 kg versus 22.6 kg), longer cardiopulmonary bypass time (128.7 min versus 87.9 min) and deeper body temperature during extracorporeal circulation (29.2degreesC versus 32.6degreesC) were identified as risk factors for postoperative arrhythmias (P<0.05). Conclusions. Continuous magnesium infusion effectively reduces the rate of arrhythmias following cardiopulmonary bypass surgery for congenital heart disease and should, therefore, be routinely used.