Key result
Administration of direct oral anticoagulants within the prior 72 hours resulted in supratherapeutic initial anti-factor Xa levels in 69% of patients initiated on heparin infusion.
Why the study?
Does prior administration of direct oral anticoagulants elevate anti-factor Xa levels in patients monitored for heparin infusions?
Observational (n=50)
Does prior administration of direct oral anticoagulants elevate anti-factor Xa levels in patients monitored for heparin infusions?
Prior administration of direct oral anticoagulants can falsely elevate heparin-calibrated anti-factor Xa levels, complicating the transition to and monitoring of heparin infusions.
Clinicians should interpret initial anti-Xa levels cautiously after recent DOAC; this Level 3 finding leaves open the need for prospective monitoring protocols.
BACKGROUND: Unanticipated drug-laboratory interactions may occur between direct oral anticoagulants (DOACs) and anti-factor Xa (AXA) levels used to monitor parenteral heparin infusions. Characterization of the extent and duration of DOAC effect on AXA levels may reduce complications with transition to heparin infusions. OBJECTIVE: To evaluate the impact of oral factor Xa inhibitors on AXA levels with and without concurrent heparin. METHODS: This retrospective descriptive study was approved by institutional review board waiver and included patients with AXA levels drawn on a heparin calibrated assay who had received a factor Xa inhibitor. Participants were divided on the basis of whether AXA levels were drawn with concurrent parenteral heparin. If transitioned to heparin, number of AXA draws required until AXA level was within therapeutic range was recorded. RESULTS: A total of 50 patients (60% rivaroxaban, 40% apixaban) met inclusion criteria. When AXA levels were drawn within 12 hours of apixaban without concurrent heparin (n = 7), 71% were greater than 1 IU/mL, and 29% were below suggested trough levels (0.7-1.1 IU/mL). For AXA levels drawn within 24 hours of rivaroxaban without concurrent heparin (n = 11), 55% were greater than 1 IU/mL, 9% were within suggested trough (0.6-1 IU/mL), and 36% were below 0.6 IU/mL. In patients (n = 28) who were initiated on heparin infusion prior to AXA monitoring, administration of the DOAC within the prior 72 hours resulted in supratherapeutic initial AXA levels 69% of the time. CONCLUSION: DOACs may cause elevations in heparin-calibrated AXA assays; this creates problematic challenges in using the AXA level to optimize heparin management.
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Macedo et al. (2017) conducted an observational in Patients requiring heparin monitoring after DOAC exposure (n=50). Direct oral anticoagulants (factor Xa inhibitors) was evaluated on Supratherapeutic initial AXA levels in patients initiated on heparin infusion within 72 hours of DOAC administration. Administration of direct oral anticoagulants within the prior 72 hours resulted in supratherapeutic initial anti-factor Xa levels in 69% of patients initiated on heparin infusion.
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