Jay Shah, MD 

Ebner M, Peter A, Spencer C, Härtig F, Birschmann I, Kuhn J, et al. Point-of-Care Testing of Coagulation in Patients Treated With Non–Vitamin K Antagonist Oral Anticoagulants. Stroke. 2015 

Routine clinical use of non-vitamin K antagonists (NOAC) has revolutionized anti-coagulation pharmacotherapy; ending frequent monitoring that was required of vitamin K antagonists. This inability to evaluate level of anti-coagulation, however, has created a quandary in acute ischemic stroke management and urgent surgery. Point of care test (POCT) has been shown to provide prothrombin levels and accelerate time to thrombolyis and such tests have been influenced by NOAC. In this study, the authors attempted to determine the diagnostic accuracy of CoaguChek POCT in ruling out relevant concentrations of rivaroxaban, apixaban, and dabigatran. 

The study was conducted at a single center. Ischemic stroke patients receiving first doses of NOAC for secondary prevention were consecutively enrolled. Blood samples were collected at the following times: before drug intake, 30 minutes, 1, 2, and 8 hours, and prior to 2nd dose and tested using the CoaguChek XS Pro POCT. PT, PTT, and anti-Xa activity were also measured and anti-Xa assay was calibrated to determine rivaroxaban and apixaban concentrations. In total, 60 patients were enrolled. Results demonstrated that results of CoaguChek POCT strongly correlated with rivaroxaban but not with apixaban or dabigatran. Anti-Xa assay also accurately detected low rivaroxaban concentrations but such assays are not routinely available.

The results suggest that POCT-results can be used to rule out relevant rivaroxaban concentrations especially if a low cut-off value is used (<1.0). This is superior to normal PT and PTT values. POCT can be used to in direct clinical practice to determine potential eligibility for thrombolysis. A limitation in this study was assessing NOAC concentrations essentially within the first 24 hours when steady-state has not been achieved. The results should be validated in larger, multi-center trials and ultimately involve trials where treatment decisions are based on POCT results.