C-TRACT Trial Overview

Post-thrombotic syndrome (PTS) can cause persistent leg pain, swelling, skin changes, and venous ulcers after deep-vein thrombosis (DVT). Unlike a fresh clot, chronic obstruction may involve scar tissue that continues to restrict venous outflow and valvular damage causing reflux. Whereas ATTRACT studied early thrombus removal to prevent PTS after acute DVT, C-TRACT evaluated treatment of established PTS. Iliac vein stenting can reopen obstructed veins, but its benefit beyond standard care, including compression, guideline-directed anticoagulation, lifestyle counseling, and ulcer care, had not been established in a large randomized trial.

The phase 3 trial randomized 225 patients with moderate or severe PTS and imaging-confirmed iliac vein obstruction at 29 U.S. centers to standard care alone or standard care plus iliac vein stenting and enhanced antithrombotic therapy. After stenting, therapeutic anticoagulation and aspirin 81 mg daily were recommended for at least 6 months unless contraindicated. The primary outcome was PTS severity at 6 months, assessed by blinded evaluators using the Venous Clinical Severity Score (VCSS). This 0–30 scale assesses pain, edema, skin changes, ulcers, and compression use, with higher scores indicating greater disease severity. Secondary outcomes included quality of life, ulcers, calf volume, recurrent venous thromboembolism, bleeding, and death.

C-TRACT builds on the smaller randomized stenting trials by Rossi et al. (2018) and Shekarchian et al. (2023), providing evidence in a larger population specifically focused on established post-thrombotic syndrome with iliac vein obstruction. The findings support restoring venous outflow in chronic disease and are consistent with the open-vein hypothesis.

The main demonstrated benefits were reduced disease severity and better quality of life. These improvements should not be interpreted as proof of ulcer healing, reduced calf volume, prevention of recurrent thrombosis, or improved survival. Equally, the lack of significant differences in these outcomes does not establish that treatment has no effect on them.

The endovascular strategy included therapeutic anticoagulation and low dose aspirin at least 6 months after stenting, unless contraindicated. This regimen may have contributed to the increased bleeding, but the trial cannot separate the effects of stenting from those of the accompanying antithrombotic therapy. Patients knew their treatment assignment, which may have influenced reported quality of life, although VCSS assessors were blinded. Enrollment reached 90% of the revised target, potentially reducing precision, particularly for uncommon adverse events.

Overall, these findings support shared decision-making for carefully selected patients with moderate or severe post-thrombotic syndrome and iliac vein obstruction, weighing symptom relief against bleeding risk. The published analysis covers 6 months; longer-term results, including 24-month follow-up for participants enrolled under earlier protocol versions, are needed to assess durability and are expected to be published in the upcoming months.

DOI: 10.1056/NEJMoa2519001