Thrombosis of atypical location: How to treat patients in the era of direct oral anticoagulants?

In 4% of cases, venous thromboembolism (VTE) involves organ-related venous territories such as splanchnic, renal, gonadal, and cerebral venous segments, and is often called venous thromboembolism of atypical location (VTE-AL). Recommendations regarding the method, intensity, and duration of anticoagulant therapy for VTE-AL are not well established. Direct oral anticoagulants (DOACs) have been a promising alternative to vitamin K antagonists in the treatment of acute VTE. However, all major clinical trials on DOACs excluded patients with VTE-AL. Therefore, data on the use of DOACs in patients with VTE-AL are still limited to case reports and small clinical series, with a relative predominance of publications on splanchnic vein thrombosis including mesenteric, splenic, portal, and hepatic vein thrombosis. The only randomized clinical trial comparing a clinical outcome of patients with acute portal vein thrombosis ran- domized to either rivaroxaban or warfarin treatment yielded significantly impaired results due to the use of an atypical rivaroxaban dose. A prospective registration of clinical outcome for DOACs used in patients with VTE-AL, in those with VTE of typical location, and in those with VTE-AL treated with enoxaparin showed similar VTE recurrence and major bleeding rates in all 3 groups. High cancer prevalence, typical for VTE-AL, significantly impacted survival as well as VTE recurrence rates and major bleeding outcomes in this study. In general, although still limited, the results for DOAC use in VTE-AL are encouraging and we do not hesitate to use DOACs, particularly rivaroxaban or apixaban, in selected patients with VTE-AL.