Predictive Value of the Triglyceride–Glucose Index for Major Adverse Cardiovascular Events in Patients with Premature Coronary Artery Disease

Background: Premature coronary artery disease (PCAD) represents a growing clinical concern. Although insulin resistance is central to atherogenesis and the triglyceride–glucose (TyG) index serves as a practical surrogate for insulin resistance, its specific prognostic capacity within younger patient cohorts remains poorly understood. This study sought to evaluate the prognostic value of the TyG index regarding major adverse cardiovascular events (MACE) and its correlation with angiographic disease severity in PCAD patients. Methods: Enrolling 382 consecutive patients presenting with acute coronary syndrome (ACS) undergoing primary or early invasive coronary angiography between July 2020 and March 2023, this retrospective study evaluated subjects stratified into premature CAD (males ≤ 45, females ≤ 55 years; n = 138) and late-onset CAD (n = 244) cohorts. Lesion complexity was evaluated via the Gensini score. Primary prognosis was evaluated via cumulative MACE during a mean follow-up of 40.7 months. Results: Baseline values for the TyG index did not exhibit significant variance between early-onset and late-onset cohorts (9.09 ± 0.71 vs. 9.06 ± 0.65, p = 0.716). Stratification by median TyG index in early-onset CAD showed expected metabolic clustering but no difference in Gensini scores (41.68 ± 25.90 vs. 44.12 ± 22.75, p = 0.321). In univariable logistic regression, baseline TyG index was not associated with MACE (OR = 1.10, 95% CI: 0.65–1.85, p = 0.732), whereas older age (OR = 1.06, 95% CI: 1.01–1.11, p = 0.017) and elevated baseline CRP levels (OR = 1.04, 95% CI: 1.01–1.08, p = 0.007) showed significant univariable associations with adverse clinical outcomes. Sensitivity analysis in non-diabetic patients (n = 275) confirmed no significant association between TyG index and MACE (OR = 0.721, 95% CI: 0.327–1.591, p = 0.418). Conclusion: In this study, the admission TyG index did not show a statistically significant relationship with coronary anatomical severity or long-term clinical outcomes in premature CAD. Risk assessment in acute coronary patients should continue to prioritize established clinical, acute inflammatory, and angiographic parameters.