Rivaroxaban and Apixaban for Initial Treatment of Acute Venous Thromboembolism of Atypical Location

Objectives To assess the outcome of direct oral anticoagulants (DOACs), specifically Xa inhibitors: rivaroxaban and apixaban, for the treatment of venous thromboembolism (VTE) of atypical location (VTE-AL), portal, mesenteric, hepatic, splenic, gonadal, renal, and cerebral veins, prospectively collected data of Mayo Thrombophilia Clinic Registry were used. Methods Patients with acute VTE-AL treated with DOACs, enrolled between March 1, 2013, and February 1, 2017, were compared with patients with VTE of typical location (VTE-TL: deep vein thrombosis of extremities and/or pulmonary embolism) receiving DOACs and with patients with VTE-AL treated with enoxaparin. Results Out of 623 patients with acute VTE receiving the study drug within 14 days of diagnosis, there were 63 with VTE-AL: 36 on DOAC, 23 on enoxaparin, and 4 on warfarin; 352 received DOAC for VTE-TL. The VTE-AL treated with DOAC/enoxaparin included the following: splanchnic (26/22), ovarian (8/2), renal (3/5), and cerebral veins (1/1), respectively. Recurrence rate (per 100 person-years) for the VTE-AL group receiving DOAC was 7.3, which was not different when compared with those for VTE-TL (2.4; P=.13) and VTE-AL groups receiving enoxaparin (23.7; P=.37). Major bleeding rate in the VTE-AL group receiving DOAC was not different compared with those for VTE-TL (7.2 vs 3.0; P=.26) and VTE-AL groups on enoxaparin (22.4; P=.31). Mortality was higher in the VTE-AL group on DOAC compared with the VTE-TL group (21.45 [95% CI, 7.87-46.69] vs 8.26 [95% CI, 5.35, 12.20]; P=.03). All patients with VTE-AL with events had cancer. Conclusion The VTE recurrence and bleeding rates for rivaroxaban and apixaban used in VTE-AL are not different from those in patients with VTE-TL and similar to that for enoxaparin.