Objectives: The aim of the current study was to analyze the clinical and procedural predictors of thrombocytopenia and the relationship between the decrease inplatelet count (DPC) and change in vWF function (?vWF) after transcatheter aorticvalve replacement (TAVR).Background: TAVR often causes temporary thrombocytopenia. At the same time, TAVR leads to a restoration of von Willebrand factor (vWF) function.Methods:One hundred and forty-one patients with severe aortic stenosis undergoing TAVR were included in the study. Platelet count and vWF function(vWF:Ac/Ag ratio) were assessed at baseline and 6 h after TAVR. Thrombocytopeniawas defined as platelet count <150/nL.Results: Median platelet count at baseline was 214/nL (interquartile range [IQR]:176-261) and decreased significantly to 184/nL (IQR: 145-222) 6 h after TAVR. The number of patients with thrombocytopenia increased from 12.8% at baseline to 29.1% after 6 h. DPC 6 h after TAVR showed a significant correlation with?vWF(r=-0.254,p= 0.002). Patients with DPC > 20% had significantly higher?vWF(10.9% vs. 6.5%,p= 0.021). Obese patients showed a significantly lower DPC (11.8%vs. 19.9%,p= 0.001). In multivariate analysis,?vWF 6 h after TAVR was the only significant predictor for DPC > 20% (p= 0.017).Conclusions:The restoration of vWF after TAVR is a significant predictor for DPCafter TAVR. An increased platelet consumption due to vWF restoration could play akey role in the development of thrombocytopenia after TAVR.