Histopathology of iliofemoral vein in-stent occlusion in postthrombotic syndrome: Findings from endovascular thrombectomy.

BACKGROUND

In-stent occlusion (ISO) remains a significant challenge in postthrombotic syndrome (PTS), with limited histopathologic characterization.

METHODS

Between January 2022 and November 2024, 19 patients with PTS (12 men; mean age 44.3 ± 12.4 years) presenting with 20 iliofemoral venous ISO underwent thrombectomy using the RevCore system. Histopathology was performed on retrieved materials from 16 limbs. Technical success, stent patency, and Villalta score were assessed. Kaplan-Meier and Cox regression identified predictors of restenosis/occlusion.

RESULTS

Technical success was 95% (19/20 limbs). In venous stent occlusions < 3 months duration (n = 12), retrieved materials contained more fresh thrombus (40.4%, p = 0.058) and old thrombus (41.3%, p = 0.040) than in occlusions ⩾ 3 months duration (n = 4), where diffuse intimal thickening (DIT) was predominant (73.8%, p = 0.008). Severe restenosis/occlusion occurred in 60% (12/20) of limbs during a median 209.5-day follow up, with median patency of 144.5 days. Villalta scores improved from 14.8 ± 7.1 to 9.4 ± 6.8 at 1 month (p = 0.002) and 9.5 ± 6.8 at the final follow up (p = 0.001). Retrieved materials containing > 50% old thrombus had a higher restenosis/occlusion risk (p = 0.026). Common iliac vein (CIV) residual stenosis ⩾ 30% (hazard ratio (HR) = 4.103; p = 0.037) and a restored common femoral vein (CFV) flow diameter < 8.0 mm (HR = 3.871; p = 0.026) predicted severe restenosis/occlusion.

CONCLUSION

In PTS-related ISO, DIT predominated in occlusion ⩾ 3 months. Old thrombus, CIV residual stenosis ⩾ 30%, and a CFV flow diameter < 8.0 mm predicted restenosis/occlusion. Integrating histopathologic assessment into postthrombectomy evaluation may help tailor and optimize management strategies for iliofemoral ISO.