BackgroundTriglyceride-glucose index (TyG), a surrogate marker of insulin resistance (IR), could be a potential prognostic marker in patients with acute coronary syndromes (ACS). We evaluated the effect of the TyG index on major adverse cardiac and cerebrovascular events (MACCE) in patients with ACS undergoing percutaneous coronary intervention (PCI).MethodsThis registry-based cohort study was conducted at Tehran Heart Center from 2015 to 2021 and the median follow-up duration was 378 days. The primary outcome was MACCE and the secondary outcomes were MACCE components: all-cause mortality, myocardial infarction, stroke, target vessel revascularization, target lesion revascularization, and coronary artery bypass grafting. For comparison among TyG quartiles (Q), the log-rank test was used. Unadjusted and adjusted hazard ratios (HRs) and their 95% confidence intervals (CIs) were used to describe the association between TyG quartiles and MACCE. A subgroup of euglycemic patients was also evaluated.ResultsA total of 13,542 patients were included. Patients in the fourth TyG quartile (Q4) were younger, had higher mean BMI, and higher prevalence of hypertension, diabetes, and dyslipidemia. The adjusted Cox model showed that a 1-unit increment of the TyG index was associated with a significantly higher risk of MACCE (aHR 1.18, 95% CI 1.08 to 1.30, p < 0.001). Among TyG quartiles, there was a higher MACCE incidence in Q4 compared to Q1 (aHR 1.29, 95% CI 1.08 to 1.53, p = 0.005). In the euglycemic subgroup of the population, there was no significant association between MACCE incidence and a 1-unit increase in TyG or among TyG quartiles.ConclusionBased on our findings, while higher TyG levels and quartiles were associated with higher rates of MACCE in ACS, there was no such effect in the euglycemic population. If confirmed in future studies, these results can be beneficial for clinicians to risk stratify these patients with an easy-to-use index and determine clinical plans based on their risk.Graphical abstract