Anti-Xa direct oral anticoagulants (DOACs) are first line therapy for stroke prevention in NVAF patients. There is no need of regular anticoagulation monitoring and dose reduction may be indicated in patients showing a high bleeding risk.

However, we still estimate 2 to 5% of major bleeding (MB) and clinically relevant non-major bleeding (CRNMB) in NVAF patients. Thereupon, we must identify other bleeding risks such as biological overdose.

The goal of this study was to investigate specific anti-Xa activity measurement as a mean to predict bleeding complications in NVAF patients.

One hundred and forty-six patients (either on apixaban or rivaroxaban) were enrolled from 2017 to 2019. The DOACs measurements were performed the day of inclusion. We determined an overdose and therapeutic underdose thresholds according to expected anti-Xa plasma range levels filled in the European heart rhythm association guide use of DOACs.

MB, CRNMB and minor bleedings and strokes occurring during the follow up (up to 3 years) were recorded. We analysed the correlation between therapeutic overdose and the studied endpoints.

To this day, the statistical analyses are still being conducted. The first results show that among the 146 patients, more or less 14% were considered overdosed. Moreover, a statistical trend was found between overdosed patients and MB or CRNMB.

In routine clinical practice, anti-Xa activity measurement could be used to predict bleeding risk in a selected population in order to adapt doses or to consider a change of molecule.