Effects of Rivaroxaban Therapy on ROTEM Coagulation Parameters in Patients with Venous Thromboembolism

Background. Rivaroxaban (Xarelto) does not require routine coagulation monitoring; however, in certain clinical situations (overdose, drug accumulation, urgent surgery) measurement of its plasma concentration is highly recommended. Currently, there is no single hemostasis test that shows a direct correlation between rivaroxaban plasma levels and anticoagulant efficacy. Objectives. This study was intended to assess the value of ROTEM in determining rivaroxaban administration. Material and Methods. Thirteen patients with venous thromboembolism and 13 healthy volunteers were compared with regard to certain ROTEM parameters and anti-FXa activity. The tests were done before the administration of 20 mg rivaroxaban (i.e. 24 h after previous administration) and 2.5 h afterwards. Results. The study group demonstrated residual activity of rivaroxaban in plasma (20 +/- 11.3 ng/mL) 24 h following the previous administration, which did not cause marked changes in clotting assays compared to controls. In the group, 2.5 h after rivaroxaban administration, prolongation of PT (PTratio 1.51 +/- 0.22), APTT (APPTratio: 1.30 +/- 0.14) and ROTEM CT (CTratio - EXTEM: 2.45 +/- 1.06, CTratio - INTEM: 1.32 +/- 0.21) were observed. The cut-off values for particular tests were created to determine if the patient had achieved desirable anticoagulant effect after rivaroxaban administration. The mean anti-FXa values were significantly lower in patients before rivaroxaban dosing than after. Conclusions. PT demonstrated better diagnostic value than APTT in rivaroxaban administration. The ROTEM clotting time (CT) according to EXTEM may be used to determine the anticoagulation effect of rivaroxaban, but is not sensitive enough to measure the residual activity of this drug.