265 - Clinical and Histopathological Outcomes of Symptomatic Iliofemoral Venous In-Stent Restenosis: A Single-Center Prospective Study of Re-Stenting versus Non-Re-stenting in 29 Patients

Purpose: In-stent restenosis (ISR) is a common complication after iliofemoral venous stenting. However, the clinical and histopathological outcomes of patients treated with re-stenting versus those managed without remain insufficiently characterized.

Materials and Methods: This single-center prospective study was approved by the institutional review board, and written informed consent was obtained from all participants. Between April 2022 and April 2025, 29 patients (mean age 45.5 ± 10.8 years; 18 male) with symptomatic ISR or stent occlusion underwent venography and endovascular biopsy. Tissue specimens were analyzed for the proportions of fresh, organizing, and old thrombus, diffuse intimal thickening (DIT), and calcified material. Twenty-two patients underwent re-stenting or stent extension, while seven were treated without additional stents (e.g., venoplasty, thrombolysis and thrombectomy). Technical success, stent patency, Villalta scores, and histopathology were assessed. Kaplan-Meier and Cox regression analyses identified predictors of restenosis or occlusion.

Results: Technical success of recanalization was 96.6% (28/29). During a median follow-up of 688.5 ± 222.4 days, 14 patients (48.3%) developed severe ISR or stent re-occlusion requiring reintervention (12 re-stented; 2 non–re-stented; p = 0.390) with a median stent patency of 180.0 ± 29.0 days. Villalta scores improved significantly from baseline (16.3 ± 7.0) to 1–3 months (6.7 ± 5.5, p < 0.001), 3–6 months (9.1 ± 7.7, p = 0.001), 6–12 months (8.6 ± 7.9, p < 0.001), and 12–18 months (6.8 ± 5.9, p < 0.001), with no significant differences between re-stented and non–re-stented groups. Histopathology showed fresh/organizing thrombus ≥50% in 14 patients, old thrombus ≥50% in 6, and DIT ≥50% in 9. Kaplan-Meier analysis showed patients with pre-existing bilateral stents (p = 0.040) and old thrombus predominance (p = 0.056) had worse patency. On univariate Cox regression, pre-existing bilateral stents (HR = 3.035, p = 0.050) and greater proportions of old thrombus (HR = 1.016, p = 0.022) were predictors of stent failure.

Conclusion: Pre-existing bilateral stents and a greater proportion of old thrombus within ISR lesions are associated with reduced stent patency. Re-stenting did not confer superior outcomes compared with non–re-stenting, suggesting that baseline clinical context and lesion profile may play a more critical role in clinical outcomes.