Clin Res Cardiol (2022).

The impact of bicuspid aortic valve morphology on von Willebrand factor function in patients with severe aortic stenosis and its change after TAVR
C. M. Xu1, N. Roth1, C. Heidel1, C. G. Jungbauer2, K. Debl2, C. Meindl2, für die Studiengruppe: UKR_TAVR
1Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg; 2Klinik und Poliklinik für Innere Med. II, Kardiologie, Universitätsklinikum Regensburg, Regensburg;


Aortic stenosis (AS) can cause acquired von Willebrand syndrome (AVWS) and valve replacement may induce von Willebrand factor (vWF) recovery. The current study aimed to investigate the prevalence of AVWS in different phenotypes of severe AS and its course after transcatheter aortic valve replacement (TAVR).


143 patients with severe AS undergoing TAVR were included in the study. Tricuspid (TAV) and bicuspid (BAV) valve morphology were determined by echocardiography and cardiac CT. Phenotypes were classified by the mean transvalvular gradient (Pmean), stroke volume index (SVI), ejection fraction (EF), and indexed effective orifice area (iEOA). vWF antigen (vWF:Ag), vWF activity (vWF:Ac) and activity-to-antigen-ratio (vWF:Ac/Ag ratio) were assessed at baseline, 6 and 24 hours after TAVR respectively. AVWS was defined as vWF:Ac/Ag ratio ≤ 0.7.  


AVWS was present in 36 (25.2%) patients before TAVR. vWF:Ac/Ag ratio did not differ in severe AS subgroups classified by SVI, EF and iEOA. However, vWF:Ac/Ag ratio was significantly lower in high-gradient compared to low-gradient severe AS [0.78 (IQR 0.67-0.86) vs. 0.83 (IQR 0.74-0.93), p < 0.05] and in patients with BAV compared to TAV [0.70 (IQR 0.63-0.78) vs. 0.81 (IQR 0.71-0.89), p < 0.05]. Normalization of vWF:Ac/Ag ratio was achieved in 61% of patients 24 h after TAVR.  In the overall study cohort, vWF:Ac/Ag ratio increased significantly in all severe AS subgroups 6h after TAVR (each p < 0.05), with no further increase after 24 h. Regarding binary logistic regression analysis, BAV was the only significant predictor for AVWS. According to ROC analysis, vWF:Ac/Ag ratio showed satisfying predictive values in the detection of TAV.


BAV morphology is a strong predictor for AVWS in severe AS. TAVR restores vWF function in most patients with severe AS independently of AS phenotype and valve morphology.