Alteration of von Willebrand Factor after Transcatheter Aortic Valve Replacement in the Absence of Paravalvular Regurgitation.

Moderate or severe paravalvular regurgitation after transcatheter aortic valve implantation (TAVI) is frequently associated with a loss of high-molecular-weight multimers of von Willebrand factor (VWF) and a reduced VWF collagen-binding capacity. It is unclear whether this phenomenon can also be observed in patients with mild paravalvular regurgitation, and whether there are differences between patients undergoing conventional aortic valve replacement (AVR) or TAVI. We analysed the multimeric structure of VWF and the ratio of VWF collagen-binding capacity to VWF antigen pre- and postoperatively in 12 patients scheduled for AVR and in 31 patients scheduled for TAVI. Echocardiographic examinations were performed pre-, intra- and postoperatively. Nine patients (75%) undergoing AVR and 18 patients (58%) undergoing TAVI showed pathological VWF functionality preoperatively (p = 0.48). Five to 7 days postoperatively, VWF functionality normalised in all patients with AVR, four of them with mild paravalvular regurgitation. VWF functionality was still altered in nine patients after TAVI (p = 0.044 between groups), five of them with and four without mild paravalvular regurgitation (p = 0.1).Altered VWF functionality was observed in nearly one-third of patients after TAVI, but not after AVR. This phenomenon was not related to paravalvular regurgitation, but may indicate differences in the response of the haemostatic system to the prosthetic heart valve design or the valve replacement procedure.