Aspirin Plus Rivaroxaban Versus Rivaroxaban Alone for the Prevention of Venous Stent Thrombosis Among Patients With Post-Thrombotic Syndrome: The Multicenter, Multinational, Randomized, Open-label ARIVA Trial.

Background: In patients with post-thrombotic syndrome (PTS), stent recanalization of iliofemoral veins or the inferior vena cava can restore venous patency and improve functional outcomes. The risk of stent thrombosis is particularly increased during the first 6 months after intervention. The ARIVA trial tested whether daily aspirin 100 mg plus rivaroxaban 20 mg is superior to rivaroxaban 20 mg alone to prevent stent thrombosis within 6 months after stent placement for PTS.

Methods: In this multinational, academic, open-label, independently adjudicated trial, patients with a Villalta score >4 points, a stenosis or occlusion of the inferior vena cava, iliac veins, or common femoral vein, successfully treated with venous stent placement, were randomized in a 1:1 fashion to the study groups. Key exclusion criteria included age <18 or >75 years, contraindications to anticoagulant use or acute venous thrombosis <3 months. The primary efficacy outcome was the composite of no occlusion in the treated segment assessed at serial duplex ultrasound examinations or no re-intervention needed to maintain patency within 6 months. Secondary outcomes, including Villalta score, quality of life, and safety outcomes were also assessed. The study was registered in ClinicalTrials.gov (NCT04128956).

Results: From 2020 through 2022, 172 patients were screened, 169 randomized and 162 included in the full analysis set, receiving either aspirin plus rivaroxaban (n=80) or rivaroxaban alone (n=82) for six months. Mean age was 42.8 (standard deviation 14.7) years, 103 (60.9%) patients were women, 154 (97.5%) were Caucasian, and leg ulcers were present in 7% patients. The primary patency rate at six months was 94.8% vs. 92.4% (absolute risk difference: 2.4%; 95 %CI -13.6%; +18.0%), respectively. The mean decrease in the Villalta score for the affected leg (without ulcer) from baseline to 6 months was -6.7 (SD 4.4) and -7.0 (SD 5.2) points (p-value 0.36), respectively. There were no differences in other outcomes or quality of life at 6 months. No major bleeding occurred.

Conclusions: The overall primary patency rate during the first six months following endovascular intervention for PTS was higher than expected and comparable between patients receiving aspirin combined with rivaroxaban and those receiving rivaroxaban alone.