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 randomized 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.