Lower risk of postoperative arrhythmias in congenital heart surgery following intraoperative administration of magnesium.

OBJECTIVES

Postoperative arrhythmias are common in children undergoing congenital heart surgery. We evaluated whether intraoperative administration of magnesium was associated with a reduced occurrence of specific postoperative arrhythmias, as has been described previously, or had a broader effect on multiple arrhythmia types, and whether there existed a dose-effect of intraoperative magnesium.

METHODS

We used a historical prospective observational cohort study. Propensity score matching using logistic regression was applied to establish similar populations of treatment groups balanced on 5 important covariates.

RESULTS

Based on propensity score-matched groups, magnesium 50 mg/kg administration was associated with a reduced odds of occurrence of postoperative arrhythmias: any arrhythmia (odds ratio [OR] = 0.50, P < .001), junctional ectopic tachycardia (OR = 0.56, P = .004), accelerated junctional rhythm (OR = 0.56, P = .089), atrial tachycardia (OR = 0.48, P = .005), ventricular tachycardia (OR = 0.52, P = .04), and atrioventricular block (OR = 0.47, P = .03). The effect of magnesium on reducing the odds of occurrence of postoperative arrhythmias did not differ between 25 mg/kg versus 50 mg/kg.

CONCLUSIONS

As many as one third of our patients undergoing congenital heart surgery had postoperative arrhythmias. Use of intraoperative magnesium was associated with a reduction in the odds of occurrence of all postoperative arrhythmias. Our results do not provide evidence that a greater dose of magnesium is associated with greater arrhythmia risk reduction. Despite the intraoperative use of magnesium, there continued to be a high residual incidence of postoperative arrhythmias, raising the question for studying new or additional agents.