Aortic annulus eccentricity before and after transcatheter aortic valve implantation: comparison of balloon-expandable and self-expandable prostheses

Abstract

Purpose: A non-circular geometry of the aortic annulus and implanted prosthesis after transcatheter aortic valve implantation (TAVI) might be relevant for short- and long-term valve function. We investigated the influence of valve type and aortic valve calcification on post-implant geometry of the catheter-based aortic valve prostheses. Methods: Eighty consecutive patients with severe aortic valve stenosis (mean age 82±6 years, 43 (53.7%) male, mean logistic Euroscore 27±14) underwent dual source computed tomography (2x64x0.6 mm or 2x128x0.6 mm) before and after TAVI. The minimal and maximal aortic annulus diameters were determined in multiplanar reconstructions exactly aligned with the annulus plane. Eccentricity of the aortic annulus or prosthesis was defined as 1-(minimal/maximal diameter). Influence of prosthesis type and degree of aortic valve calcification on post-implant eccentricity was analysed. Results: Mean aortic annulus dimensions were 21.4±2.2 mm (short diameter) by 27.0±2.4 mm (long-diameter) prior to valve implantation. Following TAVI, mean diameters were 19.9±2.0 mm by 21.6±2.0 mm. The aortic annulus showed a significantly higher eccentricity in all patients before than after TAVI (0.21±0.06 vs. 0.08±0.06, p<0.0001). Post-TAVI eccentricity was significantly lower in 65 (81.2%) patients following implantation of a balloon-expandable Edwards Sapien prosthesis as compared to 15 (18.8%) patients after a self-expandable Medtronic CoreValve prosthesis (0.06±0.05 vs. 0.15±0.07, p<0.0001). There was no significant difference regarding the extent of aortic valve calcification in patients in whom balloon-expandable or self-expandable aortic valve prostheses were implanted (mean calcium volume of 583.4±421.1 mm3 vs. 509.7±362.6 mm3, p=0.66). After TAVI, patients with a higher calcium burden (mean 1048.1±323.7mm3) showed a significantly higher eccentricity compared to patients with a lower calcium burden (mean 187.5±82.0 mm3; Eccentricity of 0.08±0.06 vs. 0.05±0.03, p=0.02). Conclusions: Catheter-based implantation of aortic valve prosthesis reduces eccentricity of the aortic annulus. Patients undergoing TAVI with a balloon-expandable prosthesis are more likely to demonstrate a circular shape of the implanted prosthesis as compared to patients with a self-expandable prosthesis. Eccentricity of the deployed prosthesis is affected by the extent of aortic valve calcification. Further studies need to assess the influence of prosthesis eccentricity on long-term outcome.