Risk of Postoperative Hypermagnesemia in Cardiopulmonary Bypass-Assisted Cardiovascular Surgery.

Key Points: The incidence of hypermagnesemia after cardiovascular surgeries using cardiopulmonary bypass is 53.2%. Most patients had mild hypermagnesemia. Cardioplegic solutions with higher magnesium content and lower eGFR were independently linked to an increased risk of hypermagnesemia. Large multicenter studies should explore the effects of hypermagnesemia on clinical outcomes in patients with advanced CKD undergoing cardiopulmonary bypass surgeries.

Background: Magnesium (Mg) administration is a common practice in cardiovascular surgeries using cardiopulmonary bypass (CPB). However, concerns persist regarding the risk of hypermagnesemia, particularly in patients with kidney dysfunction. The aims of this study were to determine the incidence of postoperative hypermagnesemia in CPB-assisted cardiovascular surgeries and identify the associated risk factors.

Methods: This was a retrospective cohort study conducted at a tertiary medical center. Data from adult patients undergoing open-heart surgery using CPB between 2018 and 2020 were analyzed. Sociodemographic, perioperative, and clinical variables were collected from electronic medical records. Logistic regression was used to identify independent risk factors of hypermagnesemia.

Results: Of the 278 patients analyzed, 53.2% developed postoperative hypermagnesemia (Mg ≥2.5 mg/dl). Mild hypermagnesemia (Mg, 2.5–3.9 mg/dl) was most common with no significant effect on clinical outcomes observed. Patients with hypermagnesemia were older, with higher comorbidity burdens and lower baseline eGFR. Cardioplegic solutions with higher Mg content and lower baseline eGFR were independently associated with hypermagnesemia (odds ratio [OR], 64.3; 95% confidence interval [CI], 12.9 to 501.1 and OR, 1.3; 95% CI, 1.1 to 1.5, respectively). Notably, ultrafiltration on CPB was associated with low risk of hypermagnesemia (OR, 0.4; 95% CI, 0.1 to 1.0; value, 0.048).

Conclusions: This study highlights the importance of mindful Mg supplementation strategies in those with advanced kidney disease. Future large-scale prospective multicenter studies should validate these findings and explore the extended effects of hypermagnesemia on clinical outcomes in patients with advanced CKD undergoing CPB surgeries.