Systemic immune-inflammation index and fibrinogen-to-albumin ratio as predictors of coronary collateral circulation in chronic total occlusion patients

Background Coronary collateral circulation (CCC) plays a vital compensatory role in maintaining myocardial perfusion in patients with chronic total occlusion (CTO) of the coronary arteries. Systemic inflammation and nutritional status are known to influence arteriogenesis; however, the roles of the systemic immune-inflammation index (SII) and the fibrinogen-to-albumin ratio (FAR) in CCC formation remain underexplored. Objective This study aimed to evaluate the association between SII and FAR levels and the development of CCC in patients with CTO. Methods A retrospective analysis was conducted on 469 patients with coronary chronic total occlusion who underwent elective coronary angiography. Patients were stratified into poorly-developed and well-developed CCC groups based on the Rentrop collateral grading system. Baseline clinical characteristics, laboratory biomarkers, and angiographic findings were compared between groups. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of poorly-developed CCC. The predictive value of SII and FAR, both individually and in combination, was evaluated using receiver operating characteristic (ROC) curve analysis. Results Patients with poorly-developed CCC exhibited significantly higher levels of SII and FAR compared to those with well-developed CCC. In multivariate logistic regression, both SII [odds ratio [OR] = 3.121, 95% confidence interval [CI]: 1.827–5.537, P < 0.001] and FAR (OR = 2.118, 95% CI: 1.248–3.227, P = 0.001) emerged as independent predictors of poor collateral formation. The combined use of SII and FAR yielded improved discriminatory performance, with an area under the ROC curve (AUC) of 0.73.Correlation analysis revealed that SII ( r = –0.377, P < 0.001) and FAR ( r = –0.815, P < 0.001) were negatively correlated with Rentrop collateral grades. Notably, FAR showed consistent statistical significance across all grades, suggesting that elevated inflammation and nutritional imbalance are strongly associated with impaired coronary collateral development. Conclusion Elevated SII and FAR are independently associated with poorly-developed CCC in patients with CTO. These biomarkers may serve as simple, cost-effective tools for clinical risk stratification and decision-making. Further prospective studies are needed to validate their prognostic utility and therapeutic implications in CCC modulation.