Study Explores Early Thrombosis After Iliac Stenting for Venous Outflow Occlusion

November 19, 2021—The Society for Vascular Surgery (SVS) announced the publication of findings from a study showing that extended use (> 10 days) of low-molecular-weight heparin (LMWH) after stenting for extensive iliofemoral venous occlusion before transition to oral anticoagulation reduces early thrombosis.

William A. Marston, MD, et al published the study in Journal of Vascular Surgery: Venous and Lymphatic Disorders (2021;9:1399-1407). Dr. Marston, who is Chief, Division of Vascular Surgery at University of North Carolina in Chapel Hill, North Carolina, serves as the study’s Principal Investigator.

“Most reported data describing stent occlusion after venous intervention have included patients across the full spectrum of venous disease,” commented Dr. Marston in the SVS press release. “Including patients with nonthrombotic disease and limited anatomic involvement as well as patients with more extensive disease has prevented the identification of specific variables relating to the outcomes for either group of patients separately.”

Dr. Marston continued, “In this study, we investigated a patient cohort with venous outflow occlusion requiring recanalization before stenting to determine the outcomes after intervention. We focused on the variables associated with early stent thrombosis in this high-risk segment of patients presenting with iliocaval outflow obstruction.”

According to SVS, the investigators retrospectively studied patients undergoing iliofemoral venous stenting at their institution (11 practitioners, two hospitals) from 2010 to 2020. The study included 106 patients (mean age, 50 ± 14 years) with either type III (single segment; 41%) or type IV (multiple segment; 59%) iliofemoral venous occlusions. One-fourth of patients had known hypercoagulable state.

As noted in the press release, treatment included:

• Mean stent length, 17 ± 63 mm
• Antiplatelet therapy in 53% of patients
• Anticoagulation in 95% of patients
• Anticoagulation involving LMWH used as a bridge to warfarin for < 10 days (n = 9) or before transition to oral anticoagulation for 2 to 4 weeks (n = 41)
• Anticoagulation with a direct oral anticoagulant (n = 39)

At 3 months after the procedure, occlusion of the stented region occurred in 26% of patients. The observed 3-year patency rates were 59% primary and 76% secondary.

Risk factors for early (within 3 months) stent thrombosis were type IV disease (odds ratio, 4.6) and hypercoagulable state (odds ratio, 3.8). Treatment with LMWH for > 10 days was associated with lower odds (0.01) of early thrombosis, reported SVS in the press release.

Dr. Marston stated, “Patients with more extensive disease (type IV) experienced a greater incidence of thrombosis. Therefore, studies that group nonthrombotic with postthrombotic patients who have undergone stenting will be less able to identify the best treatment protocols.”

“No consensus has been reached regarding the optimal postoperative anticoagulation therapy for these patients. Our study suggests that extended use of LMWH reduces early thrombosis,” concluded Dr. Marston in the SVS press release.