The impact of magnesium sulfate administration on outcomes in ICU patients with acute myocardial infarction: a retrospective cohort study.

BACKGROUND

Although magnesium acts as a natural calcium antagonist with theoretical cardioprotective effects, its clinical value in critically ill patients with acute myocardial infarction (AMI) remains controversial. This study aimed to evaluate the impact of intravenous magnesium sulfate on ICU mortality in this population, and to explore potential dose-response relationships and effect modifiers.

METHODS

This retrospective cohort study utilized the single-center Medical Information Mart for Intensive Care-IV version 3.1 (MIMIC-IV v3.1) database, which comprises patients admitted to Beth Israel Deaconess Medical Center, to examine the association between intravenous magnesium sulfate administration and mortality in critically ill patients with AMI. The primary endpoint was ICU mortality. Multivariable Cox regression, propensity score matching, and propensity score weighting were employed to control for confounders and estimate the independent effect of magnesium sulfate administration. Additional analyses included assessment of the restricted mean survival time (RMST) and quantitative evaluation of unmeasured confounding using the E-value.

RESULTS

This study included 5,650 critically ill patients with AMI. In the propensity score-matched analysis, intravenous magnesium sulfate administration was associated with a 45% reduction in ICU mortality risk (HR 0.55, 95% CI 0.42-0.71). RMST analysis confirmed an absolute survival benefit of 1.64 days at 14 days. A consistent reduction in mortality risk was observed across all secondary endpoints. A clear dose-response relationship was identified, with the greatest survival benefit at moderate cumulative doses (2.0-8.0 g) and treatment durations (1.08-3.21 days). The association remained robust to potential unmeasured confounding (E-value = 2.66). Subgroup analyses demonstrated consistent protective effects across all patient strata.

CONCLUSION

Intravenous magnesium sulfate administration is associated with lower ICU mortality in critically ill patients with AMI.