• João D Dias, Katherine Norem, Derek D Doorneweerd, Robert L Thurer, Mark A Popovsky, and Laurel A Omert.
• From Clinical Marketing, Haemonetics SA, Signy, Switzerland (Dr Dias); Operations Department (Ms Norem) and Scientific Research & Biomedical (Dr Doorneweerd), Haemonetics Corporation, Rosemont, and Medical Affairs, Haemonetics Corporation, Chicago (Dr Omert), Illinois; Hospital Division (Dr Thurer) and Medical Affairs (Dr Popovsky), Haemonetics Corporation, Braintree, Massachusetts; and Department of Surgery, Einstein Medical Center, Philadelphia, Pennsylvania (Dr Omert). Dr Omert is now with Acquired Bleeding, CSL Behring, King of Prussia, Pennsylvania.
• Arch. Pathol. Lab. Med. 2015 May 1; 139 (5): 665-73.

ContextThe clinical introduction of new oral anticoagulants (NOACs) has stimulated the development of tests to quantify the effects of these drugs and manage complications associated with their use. Until recently, the only treatment choices for the prevention of venous thromboembolism in orthopedic surgical patients, as well as for stroke and systemic embolism in patients with atrial fibrillation, were vitamin K antagonists, antiplatelet drugs, and unfractionated and low-molecular-weight heparins. With the approval of NOACs, treatment options and consequent diagnostic challenges have expanded.ObjectiveTo study the utility of thromboelastography (TEG) in monitoring and differentiating between 2 currently approved classes of NOACs, direct thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban and apixaban).DesignBlood samples from healthy volunteers were spiked with each NOAC in both the presence and absence of ecarin, and the effects on TEG were evaluated.ResultsBoth the kaolin test reaction time (R time) and the time to maximum rate of thrombus generation were prolonged versus control samples and demonstrated a dose response for apixaban (R time within the normal range) and dabigatran. The RapidTEG activated clotting time test allowed the creation of a dose-response curve for all 3 NOACs. In the presence of anti-Xa inhibitors, the ecarin test promoted significant shortening of kaolin R times to the hypercoagulable range, while in the presence of the direct thrombin inhibitor only small and dose-proportional R time shortening was observed.ConclusionsThe RapidTEG activated clotting time test and the kaolin test appear to be capable of detecting and monitoring NOACs. The ecarin test may be used to differentiate between Xa inhibitors and direct thrombin inhibitors. Therefore, TEG may be a valuable tool to investigate hemostasis and the effectiveness of reversal strategies for patients receiving NOACs.

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