Context: With increasing use of direct oral anticoagulants (DOACs), urgent reversal of these agents becomes a growing concern. Idarucizumab is a humanized monoclonal antibody fragment that specifically binds to dabigatran with higher affinity than thrombin, rapidly neutralizing its anticoagulant effect without increased risk of thrombosis.
Case details: We describe two cases in which the recommended dose of idarucizumab was unsuccessful in completely reversing the anticoagulant effects of dabigatran. Both of these patients were noted to have supratherapeutic international normalized ratios (INRs) and high dabigatran concentrations. In the first case, an 86-year-old male underwent an emergent procedure and experienced excessive hemorrhaging refractory to blood product repletion, idarucizumab, and factor eight inhibitor bypass activity (FEIBA). In the second case, a 62-year-old female in shock was found to have elevated dabigatran concentrations despite two doses of idarucizumab, continuous renal replacement therapy (CRRT), blood product repletion, and FEIBA. Both patients ultimately expired from their coagulopathies.
Discussion: These cases illustrate the potential for incomplete reversal of dabigatran with the recommended 5 g of idarucizumab and emphasize the importance of early detection of dabigatran toxicity. While direct dabigatran serum concentrations are not readily available, the INR may be a useful surrogate marker for supratherapeutic dabigatran concentrations.
Keywords: Dabigatran; idarucizumab; international normalized ratio; monitoring; reversal.