Effect of a 3-Month Single-Drug Approach Using Rivaroxaban for Symptomatic Proximal Deep Vein Thrombosis

Background: Factor Xa inhibitors, such as rivaroxaban, are increasing the convenience of treatment for deep vein thrombosis (DVT). Limited evidence exists regarding clot evaluation at 3 months after treatment for DVT. Methods and Results: We retrospectively analyzed the clinical course of symptomatic proximal DVT in patients who received 3 months of anticoagulation treatment at our hospital. Patients treated with the rivaroxaban single-drug approach were classified as group A (n=42). Patients treated with unfractionated heparin (UFH) or subcutaneous fondaparinux followed by vitamin K antagonist comprised group B (n=60) as an historical cohort. The quantitative ultrasound thrombosis (QUT) score was used to quantify clot burden before and after treatment. No significant differences were observed in patient characteristics between the groups. Serum D-dimer levels in both groups significantly improved after treatment. Clot volume assessed using QUT also reduced significantly in both groups. The QUT score in groups A and B improved from 7.5 [4.8, 12.0] to 3.0 [1.8, 5.0; P=0.000] and 7.0 [4.0, 9.8] to 3.0 [2.0, 5.0; P=0.000], respectively. The change in QUT (∆QUT) was significantly greater in group A compared with group B (-4.5 [-8.25, -2.0] vs. -2.0 [-6.0, 0.0]; P=0.005). Conclusions: We were able to demonstrate the effectiveness of DVT treatment using rivaroxaban over a period of 3 months from onset, in terms of clot regression evaluated using the QUT score.