Incremental Prognostic Value of the Triglyceride–Glucose Index Beyond the GRACE Score for Predicting 30-Day Major Adverse Cardiovascular Events in non ST-elevation myocardial infarction Patients Undergoing Percutaneous Coronary Intervention

Background: The Global Registry of Acute Coronary Events (GRACE) score is widely used for risk stratification in patients with non–ST-elevation myocardial infarction (NSTEMI). However, it does not account for metabolic factors such as insulin resistance, which may contribute to residual cardiovascular risk. The triglyceride–glucose (TyG) index has emerged as a simple surrogate marker of insulin resistance with potential prognostic value. This study aimed to evaluate the incremental value of the TyG index beyond the GRACE score for predicting short-term outcomes.Methods: In this retrospective observational design study, 110 patients with NSTEMI undergoing percutaneous coronary intervention (PCI) at Adam Malik Hospital, Medan, Indonesia, between January and December 2024 were included. The GRACE score and TyG index were calculated at admission. The primary endpoint was 30-day major adverse cardiovascular events (MACE). Discriminatory performance was assessed using receiver operating characteristic (ROC) curve analysis.Results: During 30-day follow-up, MACE occurred in 29 patients (26.4%). The GRACE score demonstrated good predictive performance (AUC 0.801; 95% CI 0.702–0.901). The TyG index alone showed moderate discrimination (AUC 0.717). The addition of the TyG index to the GRACE score significantly improved predictive accuracy (AUC 0.853; 95% CI 0.814–0.903; p < 0.05).Conclusions: The incorporation of the TyG index into the GRACE score provides incremental prognostic value for predicting 30-day MACE in NSTEMI patients undergoing PCI. This combined approach may enhance risk stratification by integrating metabolic and clinical risk factors.