Correlation of computed fractional flow and in-stent restenosis in patients with intracranial atherosclerotic stenosis

Objective: Fractional flow (FF) reserve has been developed as a gold standard for coronary intervention. Intracranial FF is also a valuable hemodynamic index to assess the severity of narrowing in intracranial atherosclerotic stenosis (ICAS). This study aims to investigate the predictive value of FF in assessing restenosis following endovascular treatment in patients with symptomatic ICAS. Methods: This retrospective study recruited 67 patients with symptomatic ICAS who received intracranial stenting between March 2019 and January 2024. FF was measured by dedicated software (AccuICAD) before and after stenting. During follow-up, patients were categorized into two groups based on the occurrence of in-stent restenosis (ISR): ISR group and non-ISR group. Multivariate regression analysis and Kaplan-Meier survival analysis were performed to identify the predictive factors for ISR. Results: Post-FF was significantly different between the ISR and non-ISR groups (0.84±0.09 vs 0.92±0.06, respectively, P<0.01). Univariate and multivariate Cox regression analyses identified post-FF (HR 0.0, 95% CI 0.0 to 0.08, P=0.005) and smoking (HR 3.06, 95% CI 1.02 to 9.19, P=0.047) as the two predictors of ISR. Receiver operating characteristic curve analysis confirmed the predictive value of post-FF for ISR (AUC=0.783, 95% CI 0.645 to 0.920, P=0.003), with a cut-off value of 0.94. Kaplan-Meier survival analysis further demonstrated that patients with a post-FF value >0.94 had a significantly lower incidence of ISR (P=0.001). Conclusion: In this study, post-FF effectively predicted ISR, providing an intraoperative evaluation value for stenting in ICAS.