von Willebrand disease is a genetic hemostatic disorder that is caused by the qualitative or quantitative dysfunction of the von Willebrand factor (VWF), which is involved in hemostasis. A similar dysfunction sometimes develops without mutations, known as acquired von Willebrand syndrome (AVWS) 1) , which has been associated with lymphoproliferative diseases, myeloproliferative diseases, malignant tumors, and hypothyroidism. Recently, it was remarkably noted that cardiovascular diseases with high intravascular shear stress could cause AVWS 2-4) . The incidence of cardiovascular disease-associated AVWS is exceptionally high, and we may encounter such patients in daily clinical settings. Further, special consideration is necessary for the treatment of bleeding since the cause of AVWS is based on the accelerated degradation of VWF.