Association between triglyceride-glucose index and OCT-defined high-risk coronary plaques in stable angina

Insulin resistance (IR) is a key driver of cardiovascular risk, yet the association between the triglyceride-glucose (TyG) index—a surrogate marker of IR—and vulnerable coronary plaques in patients with stable angina remains underexplored. This study aimed to evaluate the relationship between the TyG index and optical coherence tomography (OCT)-defined thin-cap fibroatheroma (TCFA). In this retrospective single-center study, 352 patients with stable angina undergoing coronary angiography and OCT were included. Patients were categorized into TCFA (n = 108) and non-TCFA (n = 244) groups. A multivariate logistic regression analysis was performed to identify independent indicators of TCFA, adjusting for potential confounders including demographics, comorbidities, and medication use. The discriminatory performance and clinical utility of the TyG index were evaluated using receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA), respectively. Patients in the TCFA group exhibited significantly higher TyG index levels compared to the non-TCFA group [8.98 (8.66, 9.21) vs. 8.65 (8.38, 8.90), P < 0.001]. After fully adjusting for confounding factors, the TyG index remained independently associated with the presence of TCFA (OR = 3.474, 95% CI: 1.920–6.285, P < 0.001). ROC analysis showed an area under the curve (AUC) of 0.703. The optimal cutoff value was 8.93. Patients with a TyG index > 8.93 presented with more vulnerable plaque phenotypes, characterized by thinner fibrous caps, larger lipid arcs, and increased macrophage infiltration (all P < 0.05). Furthermore, DCA demonstrated that using the TyG index provided a net clinical benefit over the default strategies. An elevated TyG index is independently associated with the presence of OCT-defined high-risk plaques in patients with stable angina. While prospective validation is needed, the TyG index shows promise as an accessible, adjunctive marker for identifying patients who may harbor vulnerable plaques.