Research Week Abstract Book - Northern Health

Haematology
THROMBIN GeneraTION MAYBE A BETTER SURROGATE MEASURE OF IN-VIVO
ANTICOAGulaTION IN THE ERA OF NEW ORAL ANTICOAGulanTS (noaC)
Ho P, Donnan G and Smith C.
Background
The in-vivo therapeutic range between effective anticoagulation and excess bleeding is narrow, and often requires monitoring.
Traditionally, the international normalized ratio (INR) of 2.0-3.0 has been a crude surrogate, but only measures the time to
the start of clot formation without evaluating total clot formation, and cannot be used for evaluating anticoagulants other than
warfarin.
The arrival of New Oral Anticoagulants (NOACs) has highlighted the need for better anticoagulation tests, particularly since
reversal agents are unavailable. Thrombin generation (TG) is a new laboratory investigation using Calibrated Automated
Thrombogram (CAT©) which measures total thrombin formation, an end-product of the coagulation cascade, and may
provide a more holistic measure of in-vivo anticoagulation.
Aim
To determine the therapeutic range of TG parameters based on the current “gold-standard” therapeutic INR range of 2.0-3.0
for warfarin, as well as describe TG parameters with enoxaparin and rivaroxaban.
Methods
De-identified INR and spiked plasma samples of rivaroxaban and enoxaparin were evaluated for thrombin generation
parameters using the CAT©.
Results
37 INR samples (range: 1.0-4.2) were evaluated. The therapeutic INR range (2.0-3.0) correlated with median ETP of
364 (range: 203–595) nM.min and thrombin peak of 177 (range: 87-200) nM, with a clear distinction from normal INR.
Rivaroxaban-spiked plasma were evaluated and produced a more concave curve with a marked decrease in thrombin peak
but without difference in ETP. Enoxaparin-spiked plasma produced curves similar to warfarin.
Conclusion
TG maybe a better surrogate measure of in-vivo anticoagulation. Further evaluation of TG parameters with NOACs, using a
therapeutic warfarin INR of 2.0-3.0 as a gold standard, may help determine the therapeutic range for these new agents.
32 Research Week Abstract Book Northern Health 2013