Association Between the Systemic Immune-Inflammation Index (SII) and the Severity of Coronary Artery Stenosis Based on the Gensini Score in Patients With Chronic Coronary Syndrome Undergoing Coronary Angiography.

Background Chronic coronary syndrome (CCS) is characterized by a dynamic course of atherosclerosis and changes in coronary artery function, shaped by lifestyle, exposure to risk factors, pharmacologic interventions, and revascularization, leading to regression, stability, or progression. Inflammatory and immune processes are integral to CCS pathogenesis and are typically chronic and low-grade. The systemic immune-inflammation index (SII = platelet × neutrophil/lymphocyte) reflects systemic inflammatory status, while coronary disease severity is quantified by the Gensini score, an angiographic index that weights percent luminal narrowing by lesion location and collateral significance and sums across segments to represent overall anatomic burden. Methodology We conducted a cross-sectional study of adult patients with CCS undergoing elective coronary angiography at Cipto Mangunkusumo National General Hospital from January 2023. Severe coronary stenosis was defined as a Gensini score ≥20. The SII was calculated from complete blood count results obtained within 24 hours before angiography. Discriminative performance of SII was assessed using receiver operating characteristic (ROC) curve analysis, with the optimal cut-off determined by the Youden index. Associations between SII and severe stenosis were quantified as prevalence ratios (PRs) using log-binomial regression models, adjusted for demographic and cardiometabolic covariates. Results A total of 296 patients were enrolled. Severe stenosis was identified in 46.3% of patients. The median SII was significantly higher in the severe stenosis group compared to the mild-to-moderate group (639.8 vs. 536.5). The optimal SII cut-off value was 639.67, yielding a sensitivity of 50.4% and a specificity of 66.0% (area under the curve = 0.601; 95% confidence interval (CI) = 0.535-0.668; p = 0.003). An SII ≥639.67 was associated with a significantly higher prevalence of severe stenosis on crude analysis (PR = 1.427; 95% CI = 1.119-1.819; p = 0.004), and this association remained statistically significant after multivariable adjustment (adjusted PR = 1.295; 95% CI = 1.044-1.605; p = 0.018). Conclusions An SII cut-off of 639.67 was independently associated with severe coronary stenosis as defined by the Gensini score, with moderate discriminatory performance. SII may serve as a complementary tool in clinical assessment to prioritize further diagnostic evaluation, particularly in resource-limited settings. However, it should not be used as a standalone diagnostic criterion. Given the cross-sectional design of this study, prospective studies are warranted to validate these findings.