Triglyceride-glucose (TyG) index predicts cardiovascular events in older coronary artery disease patients: a 6.4-year follow-up study

Background The triglyceride-glucose (TyG) index is a simple and validated surrogate marker of insulin resistance and is closely linked to cardiovascular metabolic dysfunction. Although emerging evidence supports its predictive role in general populations, long-term longitudinal data regarding the prognostic implication of the TyG index for adverse cardiovascular outcomes in patients with established coronary artery disease (CAD) remain limited. This study aimed to explore the longitudinal association between baseline TyG index and major adverse cardiovascular events (MACEs) and further evaluate its incremental predictive value for cardiovascular risk stratification in CAD patients. Methods This prospective cohort study enrolled 3642 consecutive patients with confirmed CAD. The primary endpoint was the occurrence of MACEs during long-term follow-up. Multivariable Cox proportional hazard regression models were constructed to assess the predictive effect of elevated TyG index on cardiovascular prognosis. The C-index, net reclassification index (NRI), and integrated discrimination improvement (IDI) were applied to quantify the incremental predictive performance beyond conventional cardiovascular risk factors. Results The mean age of the study population was 61.38 years. During a median follow-up of 6.4 years, MACEs occurred in 774 participants and all-cause death occurred in 275 participants. After full multivariable adjustment, elevated TyG index (>9.32) was independently associated with a significantly higher risk of MACEs (HR = 4.72, 95% CI: 3.23–6.20< 0.001). Furthermore, the inclusion of the TyG index into traditional risk models significantly improved predictive accuracy, as demonstrated by increased C-index, NRI, and IDI. Adding TyG index significantly improved the C-statistic from 0.536 (95% CI 0.519–0.627) to 0.607 (95% CI 0.527–0.638) (p<0.001). Furthermore, adding TyG index significantly improved net reclassification index (NRI)=0.168 (95% CI 0.090-0.202, p<0.001) and IDI = 0.008 (95% CI 0.008-0.014, p<0.001). The TyG index provides significant incremental prognostic value for adverse cardiovascular event prediction, indicating its potential clinical utility for optimized long-term cardiovascular risk stratification in CAD populations.