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Case Reports in Hematology
Volume 2018, Article ID 5217301, 5 pages
https://doi.org/10.1155/2018/5217301
Case Report

Rivaroxaban Treatment for Warfarin-Refractory Thrombosis in a Patient with Hereditary Protein S Deficiency

Department of Respiratory Medicine, Okinawa Prefectural Nanbu Medical Center & Children’s Medical Center, Okinawa, Japan

Correspondence should be addressed to Koken Ameku; pj.evil@ekocqema

Received 28 September 2017; Revised 2 December 2017; Accepted 4 January 2018; Published 23 January 2018

Academic Editor: Simon Davidson

Copyright © 2018 Koken Ameku and Mariko Higa. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Protein S (PS) deficiency, an autosomal dominant hereditary thrombophilia, is more prevalent in East Asian populations than in Caucasians. PS-deficient patients have historically been administered a heparin product followed by warfarin for the treatment and secondary prevention of venous thromboembolism (VTE). However, warfarin can be ineffective or causes detrimental effects in rare cases. While direct oral anticoagulants (DOACs) are being increasingly used for the treatment and prevention of VTE, their efficacy in PS-deficient patients has not been established. We describe a 91-year-old woman who presented with chronic bilateral lower leg swelling with VTE that was refractory to warfarin anticoagulation therapy for over 1 year. Her recurrent VTE was diagnosed as quantitative hereditary PS deficiency. Rivaroxaban was administered as maintenance therapy instead of warfarin; after 8 weeks, the severities of the patient’s leg swelling and venous ulcerations were significantly reduced with rivaroxaban compared to warfarin, thus demonstrating the efficacy of rivaroxaban for warfarin-refractory chronic VTE associated with hereditary PS deficiency. This case illustrates that rivaroxaban can potentially serve as therapeutic agents to treat warfarin-refractory VTE in PS-deficient patients. Further investigations are required to confirm the efficacy of rivaroxaban on the long term in this regard.