Dose adjustment based on the plasma level measurement used anti-FXa chromogenic assay on the use of non-vitamin K antagonist oral anticoagulants (NOACs) improved the overall benefit of NOACs dosing in patients with atrial fibrillation

We read the recent article by Steffel et al.1 which describing the 2021 European Heart Rhythm Association practical guide. This article indicates that anti-FXa chromogenic assays are available to measure plasma concentration of the FXa inhibitors using validated calibrators. In the section of ‘Potential indications for NOAC plasma level measurements’ of this article, the authors say that no studies have investigated if measurement of drug levels and dose adjustment based on laboratory coagulation parameters, e.g. by dose reduction in case of higher than expected levels or by dose increase in case of lower than expected levels, improve the overall benefit of non-vitamin K antagonist oral anticoagulants during long-term treatment in patients with atrial fibrillation. However, our previous investigation revealed that off-label low-dose use of direct oral anticoagulants in patients with atrial fibrillation proved suitability with indirect measurement of anti-FXa activity used the chromogenic assay could prevent bleeding events and...