Association of the triglyceride-glucose index with coronary plaque characteristics and clinical outcomes in patients with ST-segment elevation myocardial infarction

Background The triglyceride-glucose (TyG) index is a reliable surrogate marker for insulin resistance, which accelerates the development and progression of atherosclerotic cardiovascular disease. Purpose This study aimed to investigate the association of the TyG index with coronary atherosclerotic plaque characteristics and clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI). Methods Between January 2017 and December 2021, a total of 1831 STEMI patients who underwent optical coherence tomography (OCT) imaging were retrospectively enrolled. Patients were divided into three groups based on the tertiles of the TyG index: Group T1 (<8.82, n=610), Group T2 (8.82-9.41, n=611), and Group T3 (≥9.41, n=610). The TyG index was calculated as Ln [fasting triglyceride (mg/dL) × fasting blood glucose (mg/dL)/2]. Major adverse cardiovascular and cerebrovascular events (MACCE) included cardiac death, non-fatal stroke, non-fatal myocardial infarction, ischemia-driven revascularization, and rehospitalization for angina. Results The average age of patients was 58.7 ± 11.6 years, and 1,320 (72.1%) were male. Patients in the highest TyG index tertile exhibited longer lipid length and higher lipid index compared to those in the lowest and intermediate TyG index tertiles. The incidence of plaque rupture, thin-cap fibroatheromas (TCFA), and macrophages increased with increasing TyG index tertile (all P<0.05). Multivariate logistic regression analysis showed that the TyG index independently predicted culprit plaque rupture (T2: odds ratio [OR] 1.39, 95% confidence interval [CI] 1.06-1.82; T3: OR 1.51, 95%CI 1.05-2.16; T1 as reference). During a median follow-up of 4.2 years, 541 (29.9%) patients developed MACCE. Patients in the highest TyG index tertile had a significantly higher cumulative incidence of MACE (43.5% vs. 37.3% vs. 31.1%, P=0.007) than the other two groups. After adjusting for clinical risk factors and coronary plaque features, the increased TyG index was independently associated with an increased risk of MACCE (hazard ratio [HR] 1.18, 95%CI 1.00-1.38, per 1 unit increased). Conclusion In patients with STEMI, elevated TyG index increased atherosclerotic plaque vulnerability, and independently predicted plaque rupture. A higher TyG index level was a strong independent predictor of an increased risk of MACCE.