Evaluating coagulation tests in patients with atrial fibrillation using direct oral anticoagulants

Abstract

Four direct oral anticoagulants (dabigatran, rivaroxaban, apixaban, edoxaban) have been shown to be at least as effective and safe as warfarin for the prevention of stroke in atrial fibrillation and the prevention and treatment of venous thromboembolism. Although they are administered in fixed doses without routine coagulation monitoring, measurement of anticoagulant effect or drug levels may be useful to determine if: anticoagulant effect is present in patients who are bleeding or require an urgent procedure or thrombolysis; levels are within usual on-therapy range in patients with recurrent thromboembolism during treatment; and levels are outside of the usual on-therapy range in patients with overdose or with extreme clinical characteristics. Traditional coagulation assays are widely available but lack sensitivity to detect clinically relevant anticoagulant effects, and lack accuracy in quantitating drug levels. Specific drug assays are less widely available but can accurately measure drug levels and should be preferred.

Keywords:

• anticoagulants
• atrial fibrillation
• coagulation
• direct oral anticoagulant
• laboratory
• monitoring
• NOACs
• stroke

Financial & competing interests disclosure

JW Eikelboom has received grants and honoraria from Astra Zeneca, Bayer, Boehringer Ingelheim, Bristol Myers Squibb/Pfizer, Daiichi Sankyo, GlaxoSmithKline, Janssen, Sanofi Aventis and honorarium from Eli Lilly, outside the submitted work. NC Chan has received travel grants from Sanofi and honorarium from Bayer outside the submitted work. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Four direct oral anticoagulants (dabigatran, rivaroxaban, apixaban and edoxaban) are approved for stroke prevention in patients with atrial fibrillation.

• Although they are administered in fixed doses without routine coagulation monitoring, measurement of anticoagulant effect or drug levels may be useful in some situations.

• Traditional coagulation assays, such as the aPTT, PT and TT, are widely available but lack accuracy to quantitate drug levels.

• Specialized calibrated assays (clot-based or chromogenic) are less widely available but can accurately measure drug levels.

Notes