PB0924 - Additional rutoside therapy to improve deep vein thrombus resolution (Resolve-DVT): A randomized controlled pilot trial

Background: Post-thrombotic syndrome (PTS) is a frequent complication of deep vein thrombosis (DVT) in which residual venous obstruction (RVO) plays a pivotal role. Venoactive flavonoids such as (O-β-hydroxyethyl) rutoside may prevent PTS by improving thrombus resolution given their vasoprotective and anti-inflammatory properties.

Aims: This pilot study aimed to estimate the impact of additional rutoside therapy on thrombus resolution.

Methods: A single-center, assessor-blinded, randomized, controlled trial allocating patients with acute, objectively confirmed, proximal DVT of the leg to eight-week rutoside therapy in addition to standard therapy versus standard therapy alone within 48h after diagnosis. All patients gave written informed consent. A sample size of 44 was calculated based on the expected effect and patient drop-out. The primary outcome was defined as RVO ≥ 2mm transversal diameter on compressive ultrasound after 12 weeks, with pre-specified subanalysis of ≥ 4mm. Secondary outcomes included the Villalta score and calf circumference as delta compared to baseline. Odds ratios (OR, 95% confidence interval) were computed using chi-squared test; mean deltas (standard deviation) were compared using t-test. This study was approved by the medical ethics committee, registered on ClinicalTrials.gov (NCT04670432) and funded by the Netherlands Thrombosis Foundation.

Results: In total 44 patients were randomized between additional rutoside and standard therapy; clinical characteristics are shown in Table 1. After 12 weeks, the additional rutoside group had numerically less RVO than the standard therapy group with OR 0.57 (0.16-1.91) and more pronounced for ≥ 4mm with OR 0.36 (0.09-1.24) as shown in Table 2. Similarly, Villalta scores and calf circumferences decreased numerically more in the additional rutoside group compared to the standard therapy group.

Conclusion(s): Our pilot findings suggest that additional rutoside therapy improves thrombus resolution, and as a result may reduce PTS. The observed effect sizes should inform the design of a full-scale trial to assess RVO and its long-term effects on PTS.