The Von Willebrand Factor Antigen Plasma Concentration: a Monitoring Marker in the Treatment of Aortic and Mitral Valve Diseases.

Von Willebrand disease is a commonly inherited bleeding disorder caused by defects of von Willebrand factor (vWF). In the most common valve diseases, aortic valve stenosis (AVS) and mitral valve regurgitation (MVR), a bleeding tendency has been described in a number of patients. This has been associated to a high turbulence of blood flow through the compromised valve, promoting degradation of vWF with loss of high-molecular-weight multimers of vWF (HMWM), leading to an acquired von Willebrand syndrome (AvWS). We analysed three groups of patients, one affected by AVS, treated with transcatheter aortic valve implantation (TAVI), the second group of patients affected by MVR, treated with Mitraclip® mitral valve repair. The third group was represented by patients also affected by AVS, but not eligible for TAVI and treated with standard surgery. A fourth group of patients that underwent percutaneous coronary intervention (PCI) with stenting was used as a control. Our results demonstrated that the level of vWF measured as antigen concentration (vWF:Ag) increases in all cohorts of patients after treatment, while in control PCI patients, no modification of vWF:Ag has been registered. Western blot analysis showed only a quantitative loss of vWF in the pre-treatment time, but without significant HMWM modification. The monitoring of the vWF:Ag concentration, but not the quality of HMWM, can indicate the status of blood flow in the treated patients, thus introducing the possibility of using the vWF antigen detection in monitoring the status of replaced or repaired valves.