Etiology of iliocaval stent thrombosis

Although correction of iliac vein stenosis is safe and efficacious, one of its major complications is iliac vein stent thrombosis. In an attempt to examine the cause of iliac vein stent thrombosis, we reviewed the location of underlying lesions encountered after thrombectomy or thrombolysis of iliac vein stents.

A retrospective analysis was performed of all iliac vein venograms with intravascular ultrasound examinations at our office-based surgical center from February 2012 to July 2016. Patients included in the study had chronic venous insufficiency and failed compression therapy. All procedures were performed with local anesthesia and conscious sedation. Wallstents were used in all procedures for nonthrombotic iliac vein stenosis, ranging from 8 to 24 mm in diameter and 40 to 90 mm in length. Patients were followed with transcutaneous duplex every 3 months for the first year and every 6 to 12 months thereafter. Patients were placed on clopidogrel for 3 months or continued on their preexisting anticoagulants.

From February 2012 to July 2016, we performed 2228 iliac vein venograms with intravascular ultrasound examination in 1381 patients. The mean age of the patient population was 65 ±14 years (range, 21-99 years), among which 876 were female. A total of 1037 procedures were performed in the left lower extremity. Of these, 240 venograms were diagnostic. Presenting symptoms based on CEAP classification included C2 (n = 21), C3 (n = 633), C4 (n = 1065), C5 (n = 269), and C6 (n = 241). Complete thrombosis of the iliac vein stent was noted in 18 patients (0.8%) who thereafter underwent suction thrombectomy with thrombolysis. None of these patients had a prior history of deep vein thrombosis. In-stent restenosis was noted in 11 patients. Proximal lesions were found in no patients. An external iliac vein lesion was found distal to the common iliac vein stent in two patients. Common femoral vein lesions were found in six patients. These encountered lesions were then stented. All patients who underwent thrombectomy were placed on anticoagulation for 6 months. No patient were noted to suffer rethrombosis upon follow-up. No correlation with stent thrombosis was encountered for age, gender, laterality, location, presenting symptoms, or length or diameter of the stent.

Based on our experience, in-stent restenosis followed by inflow lesions in the common femoral vein are the most common causes of stent thrombosis. These data suggest a need for future research to target these areas.