Background: Endovascular treatment of post-thrombotic venous lesions has gained considerable acceptance. However, despite technical advances, intra-stent thrombosis remains common.

Objective: To determine the incidence and identify risk factors for intra-stent thrombosis after endovascular treatment of post-thrombotic venous lesions.

Methods: We conducted a retrospective single-center cohort study of 240 patients who underwent endovascular treatment for post-thrombotic syndrome. Multidisciplinary management of the patients was conducted in collaboration with the vascular medicine and interventional radiology departments. Demographic, biological and clinical characteristics, venous lesions and antithrombotic treatment were collected. Constitutional and acquired thrombophilia were also recorded. We assessed the severity of post-thrombotic femoro-popliteal sequelae according to the previously reported scanographic severity grading scale. The median follow-up period was 18 months

Results: The incidence of venous thrombosis after endovascular treatment was 16.7%. Most (52.5%) occurred within the first month, with more than 25% of thromboses occurring on the first day. Intra-stent thrombosis was highly significantly correlated with the severity of post-thrombotic femoro-popliteal sequelae, with an incidence of 47% (95% CI 34 - 60), HR 7.4 (95% CI 2.87 - 19.3) for grade 3 sequelae (p = 0.001)

Conclusions: The main risk factor identified in this cohort was the severity of post-thrombotic sequelae in the femoral vein, resulting in slow endoprosthetic flow.