The Efficacy and Safety of DOACs in Inherited Antithrombin Deficiency: A Cohort Study from a Tertiary Referral Center.

Background:  Individuals with inherited antithrombin deficiency (IATD) have a high risk of venous thromboembolism (VTE). Most VTEs are managed with direct oral anticoagulants (DOACs), but the utility of DOACs in antithrombin deficiency (ATD) is unreported.

Materials and methods:  Patients with IATD treated with DOAC were identified from our institutions' IATD registry. We assessed patients' characteristics, ATD type, and initial VTE characteristics, thrombosis recurrence and bleeding rates.

Results:  Thirty-three patients received DOACs for 73 (38.5-111.5) months (median (interquartile range)). Prior to taking DOACs, 12 (36%) patients had VTE recurrence: these occurred after anticoagulation was ceased (4), nonadherence to VKA prior to DOAC use (3), or during heparin use in pregnancy (5). There were no VTE recurrences on standard-dose DOAC, except in a noncompliant patient receiving dabigatran. There was one recurrence with compliant DOAC use-a patient receiving rivaroxaban 10 mg. Six (18%) patients experienced clinically relevant bleeding, which was predominantly menorrhagia (5/6). One major bleeding event, intracranial hemorrhage, occurred in a patient receiving full-dose rivaroxaban who had refractory hypertension (0.5 events/100 patient-years). In this cohort, compliant DOAC users had an overall VTE recurrence rate of 0.5/100 patient-years, whereas with low-dose DOACs the event rate was 3.5/100 patient-years.

Conclusion:  Standard-dose DOACs appear efficacious and relatively safe in IATD.