Although no routine coagulation monitoring is recommended during treatment with direct factor Xa inhibitors, assessment of the degree of anticoagulation may be needed in some clinical situations. Some specific assays have been developed, such as chromogenic anti-factor Xa tests that measure plasma drug concentration, but in some centres these tests are not routinely available 24/7. Point-of-care techniques can be considered as an interesting alternative to quickly assess the degree of anticoagulation at the bedside in patients treated with direct factor Xa inhibitors.

In this study, the authors compared the results obtained with 2 ‘modified’ ROTEM tests, the first using low tissue factor activation, the second based on prothrombinase-induced clotting time assays (PiCT), and standard chromogenic anti-factor Xa assays. Blood samples were obtained either from healthy volunteers before apixaban or rivaroxaban were spiked in vitro, patients treated with apixaban or rivaroxaban, or non-anticoagulated trauma patients arriving in the emergency room (control).

Interestingly, the authors report that clotting times obtained from the low tissue factor activated ROTEM was strongly correlated with apixaban and rivaroxaban concentrations, and significantly prolonged in patients treated with direct factor Xa inhibitors compared to controls. Although these results should be validated in vivo, the low tissue factor activated ROTEM may be considered as valuable diagnostic tool for bedside determination of anticoagulation level in patients treated with direct factor Xa inhibitors.

– David Faraoni

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