Magnesium Supplementation and Tachyarrhythmias: A Nonrandomized Clinical Trial

Area of Science:

• Critical Care Medicine
• Clinical Pharmacology
• Biochemistry

Background:

• Magnesium supplementation is common for acutely ill patients with hypomagnesemia to prevent tachyarrhythmias.
• Evidence supporting this practice and specific treatment thresholds is limited, with observational studies prone to bias.

Purpose of the Study:

• To investigate if magnesium supplementation in hypomagnesemic patients reduces adverse clinical outcomes.
• Utilized a quasi-experimental design for causal inference regarding magnesium's effects.

Main Methods:

• A fuzzy regression discontinuity design was employed across 93 intensive care units (ICUs) in the US and Europe (2003-2022).
• Compared patients just above and below institutional treatment cutoffs for magnesium (1.6-2.0 mg/dL).
• Analyzed data from 171,727 ICU admissions, focusing on tachyarrhythmia, hypotension, and death within 24 hours of testing.

Main Results:

• No significant difference in tachyarrhythmia occurrence (risk difference: 0.1%; 95% CI, -4.2 to 6.9) was observed.
• Magnesium supplementation showed no association with reduced hypotension (risk difference: 1.2%; 95% CI, -0.9 to 17.7) or death (risk difference: 1.4%; 95% CI, -0.6 to 5.3).
• These findings were consistent across all evaluated treatment cutoff levels.

Conclusions:

• Routine magnesium supplementation at current doses and thresholds offers no clear clinical benefit for ICU patients with serum magnesium levels near treatment cutoffs.
• The study questions the current practice of routine magnesium administration in this patient population.
• Further research may be needed to clarify the role of magnesium in critical illness.