Decoding Coronary Collateral Circulation: Predictive Value of the Systemic Immune-Inflammation Index

Objective: The current study was designed to determine the association between the Systemic Immune-Inflammation Index (SII) and the degree of coronary collateral circulation in patients with stable coronary artery disease.Methods: The current cross-sectional study conducted among five hundred (500) patients (260 males, 240 females with mean age 63.4 ± 5.1 years) with stable CAD, at cardiac unit of Dow university Hospital from January 2023 to December 2023. Sample size was calculated by Open-Epi sample size calculator with 95% confidence level, 80% power, and 5% margin of error. Non-probability consecutive sampling technique was used. Coronary collateral circulation was classified using the Rentrop score and labelled as good (2–3) or poor (0–1). Early morning venous blood samples were collected from patients after 8-10 hours fast for complete blood count, lipid profile and other inflammatory variables. The Systemic Immune inflammatory index score was measured as platelet count × (neutrophil/lymphocyte). Other Inflammatory bio-markers including C-reactive protein, neutrophil-tolymphocyte ratio, and platelet-to-lymphocyte ratio were also evaluated.Results: CAD Patients with poor collateral circulation were older and found with abnormal lipid profiles. Inflammatory markers including C-reactive protein, neutrophil/lymphocyte ratio, platelets/lymphocyte ratio, and systemic immune inflammatory index were significantly elevated in patients with poor collateral circulation (p < 0.001). Multivariate analysis confirmed SII as an independent predictor of poor collateral circulation, even after adjusting for all traditional risk factors & inflammatory markers.ROC analysis showed a Systemic Immune inflammation cutoff of 800 ×10³ predicted poor coronary collateral circulation with high accuracy (AUC = 0.89, sensitivity 84.5%, specificity 86.9%).Conclusion: The study concluded that Systemic Immune Inflammation is an independent predictor of poor coronary collateral circulation in patients with stable coronary artery disease.