Wall shear stress angle determines aortic growth in patients with bicuspid aortic valves

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The Dutch Heart Foundation Background Patients with bicuspid aortic valve (BAV) have altered flow velocity patterns with different wall shear stress (WSS) distributions in the ascending aorta compared to patients with tricuspid aortic valves. These WSS distributions are associated with aortic dilatation in cross sectional studies, however, longitudinal data demonstrating a potential causative role is missing. Purpose The aim of this study was to assess the differences in WSS distributions between BAV patients and healthy subjects and to determine the predictive value of WSS for aortic growth in patients with a BAV. Methods Forty patients with a BAV and 32 healthy matched subjects were prospectively studied by 4D-flow cardiovascular magnetic resonance (CMR). Peak velocity, pulse wave velocity, aortic distensibility, peak systolic WSS (magnitude), the different WSS components (axial and circumferential), and WSS angle were assessed in the proximal ascending aorta. WSS angle was defined as the angle between the WSSmagnitude and WSSaxial component. In the BAV patients, aortic volumetric growth over three years was determined in the proximal ascending aorta (first 5cm) based on CT angiography. Multivariate linear regression analysis was used to identify independent predictors of aortic volumetric growth. Results Of the BAV patients, 21 (53%) had a left-right fusion pattern and eight patients had Turner syndrome. WSSaxial was significantly lower in BAV patients compared to healthy subjects (p = 0.008) and WSScircumferential and WSS angle were significantly higher (both p