Higher Fibrosis-4 Index Is Associated With 1-Year In-Stent Restenosis After Carotid Artery Stenting

BACKGROUND: In-stent restenosis (ISR) is a clinically important complication of carotid artery stenting (CAS); however, practical risk markers remain understudied. Metabolic dysfunction-associated steatotic liver disease (MASLD) is associated with atherosclerotic risk, and the Fibrosis-4 (FIB-4) index, a non-invasive marker of liver fibrosis, has been linked to carotid atherosclerosis progression. Therefore, this study examined whether the FIB-4 index was associated with ISR after CAS. METHODS: We retrospectively analyzed 132 patients who underwent CAS between 2010 and 2023. ISR was defined as peak systolic velocity ≥175 cm/s on at least two consecutive duplex examinations. The primary analysis evaluated FIB-4 continuously per 1-SD increase using Cox models. Secondary exploratory analyses used a cohort-derived cutoff determined by the Youden index. RESULTS: ISR occurred in 16/132 (12%) patients. When analyzed continuously, FIB-4 was not significantly associated with ISR in univariable analysis (HR per 1-SD increase, 1.34; 95% CI, 0.88-2.04; p = 0.172) or in a parsimonious model adjusted for sex and stent design (adjusted HR, 1.40; 95% CI, 0.89-2.21; p = 0.142). The cohort-derived cutoff was 2.08. In secondary exploratory analysis, FIB-4 ≥2.08 was associated with higher ISR risk after adjustment for sex and stent design (adjusted HR, 3.93; 95% CI, 1.42-10.9; p = 0.008). CONCLUSIONS: Although continuous FIB-4 was not significantly associated with ISR, exploratory cutoff-based analyses suggested an association between higher FIB-4 and 1-year ISR after CAS. Further validation is required before clinical use.