Abstract Body (Do not enter title and authors here): Backgrounds: A recent trial has shown that the supra-annular self-expanding valve (SEV) is superior for valve function and noninferior for clinical outcomes at one year compared to the balloon-expandable valve (BEV) in patients with aortic stenosis (AS) and small aortic annulus (SAA) undergoing transcatheter aortic valve replacement (TAVR). However, differences on blood flow hemodynamics between the valves remain unclear. We aimed to investigate these differences between the SEV and BEV using four-dimensional flow cardiovascular magnetic resonance imaging (4D flow CMR).
Methods: We prospectively examined 95 consecutive patients with severe AS and a SAA who underwent TAVR between May 2018 and April 2024 (31 SEV and 64 BEV). SAA was defined as ≤430 mm² based on the trial. We compared the changes in blood flow patterns, wall shear stress (WSS), and energy loss (EL) in the ascending aorta (AAo) between the SEV and BEV using 4D flow CMR.
Results: The absolute reductions in the vortical flow, helical flow and flow eccentricity were significantly higher in the SEV group than in the BEV group after TAVR (SEV: -0.35 ± 0.88 vs. BEV: 0.15 ± 1.01, P = 0.02, SEV: -0.87 ± 0.81 vs. BEV: -0.38 ± 0.88, P = 0.003, and SEV: -0.61 ± 0.92 vs. BEV: -0.21 ± 0.83, P = 0.037, respectively) (Figure 1A-C). The absolute reduction of average WSS was significantly higher in the SEV group than that in the BEV group after TAVR (SEV: -1.9 [-3.7 – -0.90] Pa vs. BEV: -0.94 [-2.6 – 0.35] Pa, P = 0.049) (Figure 1D). The systolic EL significantly decreased after TAVR in both groups, whereas its absolute reduction was comparable between the groups (SEV: -4.9 [-7.6 – 0.21] mW vs. BEV: -4.4 [-9.5 – 1.5] mW, P = 0.61).
Conclusions: The vortical flow, helical flow, flow eccentricity, and average WSS in the AAo after TAVR were significantly decreased in the SEV compared to those in the BEV in patients with SAA undergoing TAVR. Our findings suggest the favorable profile on blood flow dynamics in the supra-annular SEV, possibly supporting its superiority of valve function.