Detection of direct oral anticoagulants with the diluted Russel's viper venom time.

Introduction: The activity of direct oral anticoagulants (DOAC) is important in acute clinical situations. Recent studies have suggested a strong influence of DOAC on the diluted Russel's Viper Venom Time (dRVVT). Therefore, it may be a suitable screening parameter for antithrombotic plasma activity of different DOAC. This prospective study aims to evaluate the sensitivity and specificity of dRVVT to detect residual DOAC activity at recommended plasma level thresholds.

Methods: A total of 80 patients were recruited, with 20 each treated with one of the four approved DOAC (apixaban, edoxaban, rivaroxaban or dabigatran), respectively. Blood plasma was collected before (baseline), at plasma peak time, and 6 and 12 h after DOAC. DRVVT was measured using the screen (LA1) and confirm (LA2) assay for lupus anticoagulant and compared with DOAC plasma levels. A reference range was calculated based on the dRVVT values of 61 healthy blood donors.

Results: All DOAC significantly prolonged the dRVVT especially at higher DOAC plasma levels. The LA1 time ≥41 s had a sensitivity ≥98% to detect edoxaban, dabigatran and rivaroxaban plasma levels ≥30 ng/mL but it was only 87% for apixaban. Sensitivity was ≥98% for all DOAC with the LA2 assay ≥36 s. The negative predictive value of a DOAC plasma level <30 ng/mL and dRVVT LA2 <36 s was 99%.

Conclusions: The dRVVT confirm assay (LA2) reliably detects residual DOAC plasma levels ≥30 ng/mL and could be useful to rapidly rule out relevant DOAC activity in emergency situations and to guide treatment decisions.