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.

BACKGROUND

In-stent stenosis (ISS) remains a significant adverse event following flow diverter (FD) placement for intracranial aneurysms. This study investigated whether admission fibrinogen (FIB) 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 4 comprehensive stroke centers between March 2016 and October 2024. The primary predictor was admission FIB 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 FIB levels and ISS was analyzed using Cox logistic regression and threshold effect analysis with 2-piecewise linear regression models.

RESULTS

Among the cohort, 90 patients (22.84%) were diagnosed with ISS, all of whom exhibited asymptomatic stenosis with a stenosis rate of ≥ 25%. Threshold effect analysis identified a nonlinear relationship between FIB levels and ISS risk, with an inflection point at 2.71 g/L. Below this threshold, each unit increase in FIB was associated with a significantly lower risk of ISS (adjusted hazard ratio: 0.27; 95% confidence interval: 0.10-0.69; P = 0.006).

CONCLUSIONS

Low admission FIB (< 2.71 g/L) independently predicts ISS risk after FD treatment. With each additional unit of FIB level, there was a 73% 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.