Introduction
Transcatheter heart valve (THV) deformation may affect leaflet kinematics and coaptation, with potential formation of hypoattenuated leaflet thickening (HALT). The flexible nitinol frame of the self-expandable THV, conforms to the native annulus shape while maintaining the prosthesis in a higher position. This arrangement is called stent-frame ‘decoupling’ and should minimize the impact of ellipticity at the valve level post-deployment.
Methods
We analysed multi detector computer tomography scan and 2D transthoracic echocardiography from 50 patients. Prosthesis eccentricity was computed at 6 levels: i) frame inflow; ii) native annulus; iii) leaflets inflow; iv) prosthesis waist; v) leaflets outflow; vi) frame outflow). Implantation depth and canting, leaflets expansion and alignment and residual anatomic sinus area ratio were also calculated. Frame inflow and native annulus eccentricity were compared to the valvular eccentricity to assess ‘decoupling’.
Results
Highest eccentricity was observed at the native annulus (0.540.12) and progressively decreases toward the outflow level (0.230.11). Subvalvular eccentricity was significantly higher as compared with valvular components (0.500.13 vs. 0.370.09, 0.001). Similar results were observed in the subgroup analysis of 23, 26, 29 and 34 size. At 12 months follow-up, HALT with mild to severe restricted movement was detected in 8 individuals (16%). There was no correlation between implantation depth and prothesis eccentricity (r= -0.08, p=0.128).
Conclusions
Stent frame decoupling can be frequently detected after (THV) replacement with Evolut R. The effect on valve performance and clinical implications remains uncertain.
