Inflow-to-Outflow Stent Frame Expansion, Ellipticity, and Decoupling in Evolut TAVR: Implications for Mid-term Hemodynamic Performance

Abstract

Background

The native aortic annulus for self-expanding transcatheter aortic valve replacement (TAVR) has variable ellipticity. A noncircular and underexpanded transcatheter aortic valve (TAV) may impact hemodynamic performance. This study aimed to quantify Evolut TAV (Medtronic) frame ellipticity and expansion 30 days post-TAVR and evaluate their impact on 1-year hypoattenuating leaflet thickening and 4-year hemodynamics.

Methods

We retrospectively evaluated 184 patients from the Evolut Low Risk substudy with high-quality computed tomography images. Frame ellipticity ratio and percent expansion were quantified at each frame node level 30 days after TAVR. Variables associated with frame deformation, 1-year hypoattenuating leaflet thickening, and 4-year hemodynamics were identified.

Results

Mean Evolut frame ellipticity was highest at the inflow (1.18 ± 0.08) and lowest at the functional leaflet region (1.05 ± 0.03) and frame outflow (1.04 ± 0.03). Frame expansion was lowest at the inflow (83.8% ± 4.9%) and highest at the functional leaflet region (97.8% ± 1.7%). TAV frame circularity and expansion significantly increased from the annular level to the leaflet region (P < .001). Mean gradient, effective orifice area, and paravalvular regurgitation at 4 years were not affected by Evolut TAV's relative noncircularity and underexpansion at the frame inflow. Frame underexpansion at the leaflet region, however, was associated with a smaller effective orifice area at 4 years.

Conclusions

Evolut frame deformation at the inflow did not affect the circularity and expansion of the stent at the functional leaflet region. Mid-term (4-year) Evolut hemodynamic performance does not appear to be impacted by frame inflow geometry.