Background/Purpose: Management of antiphospholipid syndrome (APS) centres on attenuating the procoagulant state whilst balancing the bleeding risks of anticoagulant therapy. In a minority of APS patients treated with vitamin K antagonists (VKA) maintaining the INR within the target therapeutic range is still a matter of concern

Methods: Data from consecutive APS patients attending the Thrombosis and Thrombophilia Center (St Thomas Hospital, London, UK) with poor anticoagulation control with VKA were collected. Inclusion criteria included 1) APS patients treated with VKA with INR target 2-3 for secondary prevention of venous thromboembolism (VTE) 2) Poor Anticogulation Control, defined as ‘erratic’ pattern (where more time is spent both above and below INR target) or unidirectional pattern (where time out of range is predominantly in one direction-low or high). Time in therapeutic range (TTR) was assed in all the included patients. Included patients were switched to rivaroxaban 20 mg od for secondary thromboprophylaxis.

Results: 18 APS patients were included (13 female, mean age 45.2 ± 10.4 yrs, mean disease duration 8.8 ± 6.7 yrs, mean age at onset of disease 35.1 ± 9.7 yrs). Thirteen had a history of deep vein thrombosis, 5 had both deep vein thrombosis and pulmonary embolism.  In all the included patients TTR was 65% or lower. Indication for switching to rivaroxaban was erratic INR control (mean 15 [11-21] INR tests within the last 6 months) in 13 patients and INR constantly in sub-therapeutic range in three patients, respectively. Patients were followed for a mean of 12.9 months [6-24] after starting rivaroxaban. No further VTE or major bleeding events were observed. In two women there was a worsening of menorrhagia , which was treated with conservative management.

Conclusion: In this study, the use of rivaroxaban therapy for secondary thromboprophylaxis for VTE appears safe in APS.  A larger trial  RAPS (Rivaroxaban in AntiPhospholipid Syndrome, IRSCTN 68222801) is ongoing and results will be available next year. In the interim, rivaroxaban may be considered cautiously as an alternative anticoagulant in APS patients with poor anticoagulant control with VKA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rivaroxaban-use-in-patients-with-antiphospholipid-syndrome-patients-and-previous-poor-anticoagulation-control-with-vitamin-k-antagonists/