Predictors of In-Stent Stenosis After Flow Diversion of Intracranial Aneurysms Using the FRED-X Device: A Multicenter Analysis of 6-month and 12-Month Outcomes

BACKGROUND AND OBJECTIVES: In-stent stenosis (ISS) occurs in approximately 0% to 55.3% of cases after flow diversion. The Flow Redirection Endoluminal Device-X (FRED-X) is a newer generation flow diverter with surface modifications. Our study identifies predictors of ISS after flow diversion using the FRED-X. METHODS: This was a multicenter retrospective study of patients who underwent flow diversion of an intracranial aneurysm using the FRED-X device between February 2022 and February 2024. Multivariate logistic regression was used to analyze for predictors of ISS at 6-month or 12-month follow-up. RESULTS: One fifty-four patients with 161 aneurysms underwent flow diversion with 164 FRED-X devices. At 6 months, 15.1% of cases (n = 21) developed ISS. Overall, 61.9% of patients (n = 13) developed mild ISS, 33.3% (n = 7) patients had moderate ISS, and 4.7% (n = 1) patients had severe ISS. On multivariate regression, cardiovascular disease and FRED-X stent length were associated with 6.25-fold (95% CI: 1.19-32.86) and 1.09-fold (95% CI: 1.00-1.20) higher odds of developing ISS at 6 months, whereas aneurysm width was associated with decreased odds of developing ISS (odds ratio: 0.61, 95% CI: 0.38-0.88). At 12 months, 12.0% of cases (n = 10) developed ISS. Overall 80% of this cohort (n = 8) developed mild ISS, whereas 1 patient each developed moderate and severe ISS. CONCLUSION: Our study identified cardiovascular disease, smaller aneurysm width, and stent length as independent predictors of ISS after flow diversion using the FRED-X. Patients with ISS were asymptomatic and did not require retreatment. Further prospective studies are necessary to validate these findings.