The Impact of Residual Syntax Score as a Predictor of Major Cardiovascular Events During Treatment and 3 Months After Limited Percutaneous Coronary Intervention on Lesions Causing ST-Segment Elevation Myocardial Infarction

Background: Acute myocardial infarction with ST-segment elevation (STEMI) is one of the leading causes of morbidity and mortality due to cardiovascular disease. In STEMI patients with multivessel disease, percutaneous coronary intervention (PCI) strategies are often limited to culprit-only PCI, leaving residual lesions that may increase the risk of major cardiovascular events (MCEs). The residual SYNTAX Score (rSS) is a quantitative tool for assessing the anatomical burden of residual coronary artery disease after intervention and is thought to have predictive value for MCE. Objective: This study aims to evaluate the role of the residual SYNTAX score as a predictor of major cardiovascular events during hospitalisation and within 3 months after limited percutaneous coronary intervention on the causative lesion in STEMI patients, as well as to determine the optimal rSS cut-off value in predicting these events. Methods: This study is an analytical observational study with a retrospective cohort design conducted at Ngoerah Hospital from January to September 2025. A total of 166 STEMI patients who underwent PCI limited to the causative lesion and met the inclusion criteria were analysed. The residual SYNTAX score was calculated based on post-PCI angiography and categorised using Receiver Operating Characteristic (ROC) analysis. Major cardiovascular events during hospitalisation and 3 months after PCI were recorded. Analyses were performed using the Chi-square test, ROC curve, and Cox regression to determine independent predictors. Results: Of the 166 patients, 64 patients (38.6%) had high rSS (≥8.5), and 102 patients (61.4%) had low rSS (