Risk factors for stent occlusion after catheter-directed thrombolysis and iliac vein stenting in the treatment of May-Thurner syndrome with iliofemoral deep vein thrombosis: a retrospective cohort study.

Background: This study aimed to identify the risk factors for stent occlusion in patients with iliofemoral deep vein thrombosis (DVT) secondary to May-Thurner syndrome (MTS) who underwent catheter-directed thrombolysis (CDT) and iliac vein stenting. Methods: A retrospective analysis was performed on 44 patients who underwent CDT and iliac vein stenting for MTS with iliofemoral DVT between October 2001 and March 2018. MTS was diagnosed based on extrinsic compression of the left common iliac vein (CIV) by the overlying right common iliac artery (CIA) on computed tomography (CT). Clinical records of the study population were reviewed to collect baseline data, procedural characteristics, and outcomes. Final venograms showing diffuse and irregular wall thickening in the iliofemoral vein were considered to indicate a chronic post-thrombotic lesion. The stent position was categorized as follows: confluence coverage without touching the contralateral inferior vena cava (IVC) wall, IVC extension contacting the contralateral IVC wall, or distal to the iliocaval junction. Stent patency was assessed using duplex ultrasonography. Risk factors for stent occlusion were assessed using univariate and multivariate Cox proportional hazard models. Results: The median duplex ultrasound follow-up period was 25 months (range, 1-196 months). The overall cumulative patency rate at 12 months was 70.0%. In the univariate Cox regression, factors significantly associated with stent occlusion included symptom duration >2 weeks before CDT, partial thrombolysis (50-99% of thrombus removal), chronic post-thrombotic lesions, and stent position. Multivariate Cox regression showed that chronic post-thrombotic lesions [hazard ratio (HR) =7.15; 95% confidence interval (CI): 1.32-38.81; P=0.023] and a stent distal to the iliocaval junction (HR =5.59; 95% CI: 1.46-21.38; P=0.012) were significantly associated with stent occlusion. Conclusions: Chronic post-thrombotic lesion and a stent distal to the iliocaval junction were important risk factors for stent occlusion in patients who underwent CDT and iliac vein stenting.