Association between glycemic variability and mortality after coronary stent implantation in critically ill patients: a retrospective cohort study

BACKGROUND: Glycemic variability (GV) has been associated with adverse outcomes in critical illness; however, its prognostic relevance in patients undergoing coronary stent implantation remains unclear. METHODS: In this retrospective cohort study, we analyzed 2,427 adult patients who underwent coronary stent implantation and were admitted to the coronary care unit (CCU) or cardiovascular intensive care unit (CVICU) using data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Glycemic variability (GV) was defined as the coefficient of variation of blood glucose (standard deviation/mean ×100%). The primary and secondary outcomes were in-hospital and 365-day all-cause mortality. Associations were assessed using multivariable Cox models. Nonlinear relationships, survival differences, discriminative ability, and mediation effects were evaluated using restricted cubic splines, Kaplan-Meier analysis, time-dependent receiver operating characteristic (ROC) curves, and mediation analysis, respectively. External validation was performed in the eICU Collaborative Research Database. RESULTS: Patients in the highest GV quartile had significantly higher risks of in-hospital mortality (HR 2.58, 95% CI 1.30, 5.13) and 365-day mortality (HR 1.77, 95% CI 1.20, 2.60) compared with those in the lowest quartile. A significant trend across GV quartiles was observed (p for trend < 0.01), although excess risk was primarily driven by the highest quartile. These associations were consistent across analyses and were externally validated. Mediation analysis indicated that blood urea nitrogen accounted for 7.7% and 10.3% of the association, respectively. CONCLUSIONS: Elevated glycemic variability (GV) was independently associated with increased risks of in-hospital and 365-day all-cause mortality after coronary stent implantation. GV may serve as a simple and clinically accessible marker for risk stratification in this population.