It has been demonstrated that a higher risk of unfavorable outcomes is linked to greater postoperative glycemic variability. Nevertheless, it is still unclear how postoperative GV affects long-term mortality following heart surgery, especially in light of other related interaction variables. This study aimed to ascertain whether preoperative hemoglobin A1C (HbA1C) levels or diabetes status contribute to the risk of GV-related one-year mortality after CABG and whether postoperative GV is linked to one-year mortality.
Retrospective analysis was done on data from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database that came from 3,598 patients who had CABG surgery and were later hospitalized to the intensive care unit between 2008 and 2019. Based on their postoperative GV levels, patients were divided into 2 groups: the GV-Low group (GV < 0.219, n = 2,399) and the GV-High group (GV ≥ 0.219, n = 1,199).
The relationship of postoperative GV and one-year mortality was investigated using Cox proportional hazards models. Cumulative survival was evaluated using Kaplan-Meier curves, and the association between postoperative GV alterations and one-year mortality was investigated using restricted cubic splines (RCS). The effect of postoperative GV alterations on one-year mortality was then evaluated using Cox regression.
After coronary artery bypass grafting, the one-year mortality rate was 4.92%. With a hazard ratio of 1.273 (95% CI, 1.155-1.405) per unit increase in Log-transformed GV in the unadjusted model, 1.255 (95% CI, 1.136-1.390) in the partially adjusted model, and 1.146 (95% CI, 1.035-1.269) in the fully adjusted model, multivariate Cox proportional hazards analysis demonstrated a significant relationship between postoperative GV and one-year mortality.
A linear pattern was seen in the connection (p-non-linearity = 0.962). Furthermore, individuals with preoperative HbA1c levels < 7.0% (HR, 1.188; 95% CI, 1.039-1.357) or those without diabetes mellitus (DM) had a greater connection (hazard ratio [HR], 1.318; 95% CI, 1.072-1.622).
Overall, higher one-year mortality after CABG is linked to increased postoperative GV, especially in individuals without DM. These results might provide useful direction for developing focused strategies to lower mortality following heart surgery in general.
Reference:
Ma, J., Qin, J., Mao, F., He, C., Ma, D., & Zhu, J. (2025). Postoperative glycemic variability as a predictor for one-year mortality following coronary artery bypass grafting: a retrospective cohort study. BMC Cardiovascular Disorders, 25(1), 845. https://doi.org/10.1186/s12872-025-05326-y
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