Fibrinogen Levels Below a Critical Threshold Serve as a Protective Factor Against In-Stent Stenosis Following Flow Diverter Treatment for Intracranial Aneurysms: A Multicenter Retrospective Cohort Study.

Abstract

Background: In-stent stenosis (ISS) remains a significant adverse event following flow diverter (FD) placement for intracranial aneurysms. This study investigated whether admission fibrinogen levels could predict ISS occurrence.

Methods: We conducted a multicenter retrospective cohort study of 394 consecutive patients who underwent FD treatment for intracranial aneurysms across four comprehensive stroke centers between March 2016 and October 2024. The primary predictor was admission fibrinogen level, and the primary endpoint was angiographically confirmed ISS during 12.63±9.29 months of follow-up. Multiple variables were collected, including patient demographics, aneurysm characteristics, procedural details, and vascular risk factors. The association between fibrinogen levels and ISS was analyzed using Cox logistic regression and threshold effect analysis with two-piecewise linear regression models.

Results: Among the cohort, 80 patients (20.3%) were diagnosed with ISS,all of whom exhibited asymptomatic stenosis with a stenosis rate (SR) of ≥25%. Threshold effect analysis identified a non-linear relationship between fibrinogen levels and ISS risk, with an inflection point at 2.71 g/L. Below this threshold, each unit increase in fibrinogen was associated with a significantly lower risk of ISS (adjusted odds ratio 0.27; 95% confidence interval 0.58 - 1.47; P=0.006).

Conclusion: Low admission fibrinogen (<2.71 g/L) independently predicts ISS risk after FD treatment. With each additional unit of fibrinogen level, there was a 0.73-fold reduction in the risk of ISS after FD treatment at follow-up. These results may help identify patients at higher risk for ISS who might benefit from more intensive.