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We read with great interest the article by Curnow et al,1 describing treatment of von Willebrand disease (VWD), as published in a recent issue of the journal, together with other interesting articles related to such disorders, as appearing in a recent issue of Seminars in Thrombosis & Hemostasis. We thereforewish to report our experience of thefirst successful use of a highly purified plasma von Willebrand factor (VWF) concentrate containing little FVIII in the long-term prophylaxis of severe vWD in Slovakia. VWD is the most common inherited bleeding disorder caused by a quantitative and/or qualitative abnormality in the adhesive plasma protein VWF.2 VWF represents a highmolecular-weight adhesive glycoprotein that plays an essential role in the primary hemostasis by promoting platelet adhesion to the subendothelium and platelet plug formation at the sites of vascular injury. VWD is classified into three major types: partial quantitative deficiency (type 1), qualitative deficiency (type 2), and complete quantitative deficiency (type 3). VWD type 2 is further divided into four variants (2A, 2B, 2N, 2M), based on the characteristics of the dysfunctional VWF.1,3 Individuals presenting with clinical manifestations of VWDmay have amild,moderate, or severe bleeding tendency since childhood, usually proportional to thedegree of theVWF deficiency/defect.4 There are two principle treatments of choice in VWD: desmopressin (DDAVP) and substitution therapywith bloodproducts containing VWF (with/without factor VIII; FVIII). Other forms of treatment can be considered as adjunctive or alternative to those mentioned above.5 We present amale patient (now aged 34 years) with VWD type 3 (►Table 1). Our study was conducted in accordance with the Declaration of Helsinki. It was also approved by the institutional ethics committee on human research and informed consent was obtained. Early after birth, several spontaneous bleeding manifestations presented, which, over subsequent years, continued with many mucosal and joint bleeding episodes; these promoted the development of arthropathy. Substitution therapy was historically administered “on demand” during these events. From 1999, the then 17-year-old patient was subsequently treated with regular prophylactic administration of VWF/FVIII plasma-derived concentrates. Despite preventive administration, the patient continued to have recurrent mucosal bleeding and epistaxis, albeit with less frequent bleeding into joints. FromDecember 2015, he was switched from a concentrate containing both VWF and FVIII to a highly purified plasma VWF concentrate containing little FVIII (Willfact; LFB Biomedicaments, France). Levels of plasma VWF and FVIII in individuals with VWD can be regulated by the infusion of plasma-derived concentrates containing either VWF alone or VWF with FVIII.1 Available concentrates contain different amounts of VWF and FVIII, and the appropriate dosage should, therefore, be defined according to the specific product’s characteristics.6 The primary symptoms of the severe form of VWD, comprising deficiency of both VWFand FVIII, may therefore comprise frequent hemophilia-like joint bleeds or recurrent spontaneous mucosal bleeding (e.g., epistaxis and gastrointestinal bleeding). Therefore, in patients with frequent bleeding, the treatment rationale is use of secondary long-term prophylaxis.6,7 Although patients with severe VWD produce FVIII, Letter to the Editor

seminars in thrombosis and hemostasis

Successful Use of a Highly Purified Plasma von Willebrand Factor Concentrate Containing Little FVIII for the Long-Term Prophylaxis of Severe (Type 3) von Willebrand's Disease