2026 Eastern States Conference

Title: Magnesium boluses for post operative atrial fibrillation prevention 

Authors: Alyssa Mills PharmD, Bradley Troyer PharmD, BCCCP, Emma Kabalka, PharmD and Brian Burton, MS. 

Objective: Identify if the use of magnesium boluses in addition to standard of care prevents post-operative atrial fibrillation (POAF) after coronary artery bypass surgery (CABG).  

Self-assessment: In this study, why might the magnesium bolus group not have shown a significant reduction in POAF compared to standard of care?  
A. Magnesium caused more side effects 
B. Magnesium levels were not consistently maintained above 3mg/dl 
C. Standard of care also included magnesium therapy
D. Magnesium levels were not measured appropriately  

Background: POAF occurs in 20-50% of all cardiac surgeries. Magnesium may lower risk by prolonging the atrial refractory periods and reducing myocardial excitability. This study evaluates adding magnesium boluses to standard care to prevent POAF after CABG.  

Methods: Medical records of 290 postoperative CABG patients admitted to Charleston Area Medical Center Memorial Hospital between January 1st, 2021, and March 21st, 2025 were reviewed. The first cohort received standard of care atrial fibrillation prophylaxis with amiodarone and beta-blockers while the other received magnesium boluses in addition to standard of care to maintain magnesium levels above 3mg/dL. 

Results: When analyzing the difference between patients who received magnesium boluses vs standard of care, there was no significant difference in the rate of POAF occurrence between the two cohorts (47% vs 36%, P=0.0957). For secondary outcomes, there was no difference between hours of vasopressors, hospital length of stay, or stroke occurrence. When examining compliance with the magnesium replacement protocol in the bolus cohort, 90% of patients had a low magnesium day and only 31% of those patients received adequate replacement. 

Conclusions: It is unclear whether POAF rates reflect magnesium inefficacy or failure to maintain levels consistently above 3mg/dL in the bolus cohort. The number of replacements varied despite subtherapeutic levels. This could have been due to our institution's protocols not appropriately being followed. A lack of appropriate documentation in the standard of care group may have also been a significant confounder. Prospective studies are needed to evaluate optimal magnesium replacement and effectiveness.