Direct oral anticoagulants (DOACs) have gained in popularity over vitamin K antagonists for the treatment of venous thromboembolism, however their efficacy is not routinely monitored. It is therefore a clinical challenge to know how to respond when treatment with DOACs fails, and there is little formal guidance on how to manage these patients. We sought to characterize VTE patients who experienced DOAC failure at our institution, and rationalize subsequent treatment strategies. We collated the details of 54 consecutive patients with suboptimal response or breakthrough thrombosis on a DOAC, from our large specialist-led thrombosis clinic. Initial treatment changes were recorded, as well as long-term anticoagulation therapy and treatment outcomes. On first recognition of DOAC failure, 69% of patients were temporarily switched to therapeutic-dose low molecular weight heparin; most of the remaining patients were treated with an alternative DOAC regimen. After a limited period of parenteral treatment, 84% of patients returned to oral anticoagulation, the majority of whom experienced no further treatment failures. By the end of follow-up, 72% of patients were either on long-term DOAC therapy or had completed treatment altogether. In the absence of evidence or guidelines, brief rescue of anticoagulation with parenteral therapy can be an effective strategy when treatment with a DOAC fails.
Keywords: Anticoagulants; Antithrombins; Factor Xa inhibitors; Treatment failure; Venous thromboembolism.