Short-Term Subcutaneous Fondaparinux and Oral Edoxaban for Acute Venous Thromboembolism

Background: No studies have compared treatment efficacy between subcutaneous (SC) fondaparinux and oral edoxaban, which are categorized as factor Xa inhibitors, for venous thromboembolism (VTE) in the acute phase, and only a limited number of imaging-based quantitative studies have evaluated treatment. Methods and Results: In this open-label, randomized study, 50 patients with acute non-massive pulmonary embolism (PE) and/or deep-vein thrombosis (DVT) were assigned to fondaparinux or edoxaban groups. Lower-limb venous ultrasonography (US), and chest computed tomography (CT) were compared before and 7 days after treatment. Thrombus volume in DVT was calculated using quantitative ultrasound thrombosis (QUT) score on US. For evaluation of PE thrombus volume, lung perfused blood volume (PBV) on CT was calculated. The measurements before and after treatment, respectively, were as follows: QUT score: fondaparinux, 8.1 +/- 7.3 to 4.1 +/- 4.5; edoxaban, 7.7 +/- 6.3 to 4.4 +/- 4.3, both significant decreases (P=0.001, P<0.001, respectively); lung PBV: fondaparinux, 32.0 +/- 7.8 to 32.1 +/- 8.2 HU; edoxaban, 34.2 +/- 8.6 to 38.5 +/- 11.8 HU (P=0.732, P=0.426, respectively). On subjective CT-based evaluation, all pulmonary artery-related filling defects decreased/disappeared after treatment in both groups (P=NS). Conclusions: Both SC fondaparinux and oral edoxaban are effective in acute VTE. Effects on thrombus regression on imaging-based quantitative measurement did not differ between the 2 drugs.