Newer Oral Anticoagulants: a Review of Laboratory Monitoring Options and Reversal Agents in the Hemorrhagic Patient

Purpose: Available evidence on laboratory monitoring of coagulation assays and reversal strategies for the management of hemorrhagic events associated with the newer anticoagulants is reviewed.

Summary: While there are no published studies with dabigatran and prothrombinase-induced clotting time (PiCT) and no chromogenic assays available to measure the anticoagulant effects, thrombin time and activated partial thromboplastin time (aPTT ) may be used to detect the presence of dabigatran. Although ecarin clotting time is sensitive to elevated concentrations of dabigatran, only a small fraction of institutions have access to this assay. Rivaroxaban and apixaban prolong prothrombin time, dilute prothrombin time, aPTT, Heptest results, and PiCT to varying degrees, having the most- pronounced effects at higher concentrations. In contrast, the chromogenic antifactor Xa assay proved to be sensitive to lower amounts of rivaroxaban and apixaban with less variability. Despite the expectations with these newer anticoagulants, the associated risk of bleeding is significant, and there are insufficient data depicting treatment options in emergency situations. Until four-factor prothrombin complex concentrates (PCCs) become available in the United States, the obtainable options are activated PCC, three-factor PCCs, and recombinant factor VIIa.

Conclusion: Although there is currently no gold standard of measurement for any of the newer anticoagulants, the published literature enables practitioners to evaluate the efficacy and sensitivity of a majority of these assays. Prohemostatic agents can be used in instances of severe, life-threatening hemorrhagic complications.