Do new oral anticoagulants require laboratory monitoring? The clinician point of view.

Although no laboratory monitoring is needed for new anticoagulants, the measurement of their activity is required in special clinical situations. Standardised tests have been developed for rivaroxaban and dabigatran which allow the measurement of the patient's response to the drug at Cmax (2 to 3 hours after intake) or at trough (before repeated administration). The results can be expressed in mg per ml of plasma and compared to the expected concentrations. The influence of the new anticoagulants of coagulation assays has been determined. Several clinical cases of major bleeding have been reported and a severe coagulopathy was found in these patients (prolonged PT and aPTT, increased drug concentration in plasma). These observations raise the question regarding the potential benefit of laboratory coagulation monitoring from time to time. Trials are needed to determine the relationship of assay results with bleeding or thrombotic complications. Pros and Cons laboratory measurements are discussed.