Association between the triglyceride–glucose index and multi-vessel coronary artery disease in coronary artery ectasia patients: a cross-sectional study

Coronary artery ectasia (CAE), a rare pathological entity characterized by pathological coronary dilation, frequently coexists with coronary artery disease (CAD). Emerging evidence implicates insulin resistance (IR) in atherosclerotic progression, with the triglyceride–glucose (TyG) index—a validated IR surrogate—being clinically associated with CAD severity. However, its relationship with multi-vessel CAD in CAE populations remains underexplored. This cross-sectional study analyzed 585 CAE patients with CAD undergoing percutaneous coronary intervention (PCI) at Fuwai Hospital (2016–2018). Participants were stratified by TyG index (low/high) and CAD severity (single/multi-vessel CAD). Multivariable-adjusted logistic regression was used to evaluate the association between the TyG index and multi-vessel CAD. Restricted cubic splines (RCS) were applied to assess dose–response relationships. Incremental predictive value was quantified via C-statistics, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) relative to baseline risk models. The study population had a mean age of 58.1 ± 10.6 years, and 496 (84.8%) were male. The TyG index was independently associated with multi-vessel CAD in the overall CAE cohort (completely adjusted odds ratio (OR): 1.866, 95% confidence interval (CI): 1.203–2.895 for continuous TyG; and completely adjusted OR: 2.578, 95% CI: 1.558–4.266 for categorical TyG). However, heterogeneous associations were observed in type 2 diabetes mellitus (T2DM) and non-T2DM subgroups. A non-linear relationship was observed between the TyG index and multi-vessel CAD in the overall population ( P overall = 0.002, P -non-linear = 0.025). Adding the TyG index to the baseline risk model improved the predictive performance for multi-vessel CAD in the overall cohort. The TyG index is independently associated with multi-vessel CAD in CAE patients, particularly in T2DM populations. In non-T2DM individuals, a threshold effect suggests that significant IR is required to increase CAD risk. The TyG index enhances the prediction of multi-vessel CAD and may serve as a valuable biomarker for risk stratification in CAE patients. Further studies are needed to validate these findings and explore underlying mechanisms. Clinical Trial Number (ChiCTR2100047090|| https://www.chictr.org.cn/ ). Registration Date: 2021-06-08.