Huibo Wang, Guosong Jiang, Xiaoxiao Qu, Jinmeng Zhou
BACKGROUND: The triglyceride glucose (TyG) index, a surrogate marker of insulin resistance, has been linked to cardiovascular risk. However, its prognostic role in critically ill patients with atherosclerotic cardiovascular disease (ASCVD) remains unclear. METHODS: In this retrospective cohort study using the MIMIC-IV database, we identified 2,493 ASCVD patients and stratified them into TyG tertiles upon Intensive Care Unit (ICU) admission. Primary outcomes were 30-, 90-, and 365-day mortality. Secondary outcomes included the use and timing of mechanical ventilation (MV) and vasopressors. Cox regression, restricted cubic spline, and Fine-Gray competing risk models were applied. Propensity score matching (PSM) was performed as a sensitivity analysis. Subgroup analyses were conducted by age, sex, race, hypertension, diabetes, and statin use. Mediation analysis using white blood cell (WBC) count explored systemic inflammation. RESULTS: Higher TyG tertiles were consistently associated with increased mortality: 30-day (HR 1.85, 95% CI 1.46-2.36, P < 0.001), 90-day (HR 1.73, 95% CI 1.39-2.15, P < 0.001), and 365-day (HR 1.66, 95% CI 1.37-2.03, P < 0.001). These associations remained robust in propensity score-matched (PSM) analyses. Elevated TyG was also linked to greater need for MV (OR 1.93, 95% CI 1.66-2.24, P < 0.001) and vasopressor support (OR 1.58, 95% CI 1.35-1.86, P < 0.001) within the first 24 h, and to earlier initiation of these interventions in competing risk models (MV): sHR (subdistribution hazard ratio) 1.46, 95% CI 1.35-1.57, P < 0.001; vasopressor use: sHR 1.41, 95% CI 1.30-1.53, P < 0.001. WBC count partially mediated the TyG-mortality association, accounting for 22.18% of the total effect (P < 0.001) for 30-day mortality. In exploratory subgroup analyses, the association between TyG and mortality appeared more pronounced in nondiabetic patients (30-day HR 1.58, 95% CI 1.35-1.84) than in diabetic patients (HR 1.13, 95% CI 0.94-1.36), although these findings should be interpreted cautiously. CONCLUSION: In critically ill patients with ASCVD, higher TyG index was associated with adverse outcomes, including increased mortality and earlier initiation of organ-supportive interventions. These findings suggest that TyG could serve as a practical biomarker for early risk stratification in this high-risk population, though prospective studies are warranted to confirm its clinical utility.