Rivaroxaban reversal

Background

Millions of people in the United States are on at least one type of anticoagulant medication, for a number of medical conditions including atrial fibrillation, placement of cardiac stents, stroke prevention, deep vein thrombosis/pulmonary embolism, and prevention of acute coronary syndromes.
In the past several years, there have been numerous new anticoagulant medications that have entered the market, with claims of easier dosing and need for less monitoring compared to older generation medications.
However, with use of these new medications in increasing numbers by the public, and uncertainty regarding the best mechanisms of reversal, this can lead to a difficult situation for the emergency physician when a patient on one of these medications presents with a catastrophic intracranial or gastrointestinal bleed.
Since the introduction of the direct thrombin inhibitor (DTI) dabigatran (Pradaxa) and the Factor Xa inhibitors rivaroxaban (Xarelto) and epixiban (Eliquis), there have been multiple studies that have attempted to determine 1) which test(s) could be used to assess whether a patient has supratherapeutic drug levels, and 2) the best way to reverse anticoagulation in patients on these medications who have a life-threatening bleed.
However, the available studies are lacking in that none of these studies are assessing human subjects taking these medicaitions who are potentially supratherapeutic and symptomatic.

Patient taking rivaroxaban with a life-threatening bleeding event (GI, ICH, etc.)

clinical manifestation of GI bleeding
low H&H
non contrast head CT showing ICH
Factor Xa inhibiting agents affect the PT, however the degree of PT elevation does not directly correlate with that produced by warfarin and is not reliable in assessing level of anticoagulation with rivaroxaban or epixaban.
Antifactor Xa assays can be performed but the test needs to be calibrated specifically for these drugs, rather than using the calibration scale for LMWH, in order for the results to be reliable. However, Antifactor Xa assays measure drug levels and not degree of coagulopathy.
One test that has shown promise in determining level of coagulopathy and reversal of coagulopathy with both DTIs and Xa inhibitors is the Calibrated Automated Thrombogram (CAT) test, as shown with in vitro studies on reversal of dabigatran and rivaroxaban. CAT measures coagulability by measuring the thrombin concentration of a sample. It is a fluorogenic assay that compares the concentration of thrombin in clotting plasma with a constant known thrombin activity in a parallel non-clotting sample. This test could potentially be a global test of coagulation state and is therefore potentially very useful in the clinical setting to assess patients with any possible coagulopathy.

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