Orifice areas of balloon-expandable transcatheter heart valves: a three-dimensional transesophageal echocardiography study

J Am Soc Echocardiogr. 2021 Dec 22;S0894-7317(21)00881-6. doi: 10.1016/j.echo.2021.12.009. Online ahead of print.


Introduction: Accurate expected effective orifice area (EOA) values for balloon-expandable (BE) transcatheter heart valves (THV) are crucial for preventing patient prosthesis mismatch (PPM) and assessment of THV function. Currently published reference EOAs, however, are based on transthoracic echocardiography (TTE) which may be subject to left ventricular outflow tract diameter underestimation and/or suboptimal THV Doppler interrogation. The objective of this study was to establish reference EOA values for BE THVs based on Doppler and three-dimensional (3D) transesophageal echocardiography (TEE).

Methods: We retrospectively reviewed 212 intra-procedural TEEs performed during BE THV implantation with optimal post-implant Doppler and 3D imaging. We compared continuity equation-derived EOAs to geometric orifice areas by 3D-planimetry (GOA3D). Performance indices (i.e., EOA normalized to valve size) and PPM rates were determined. TTE-based EOAs performed within 30 days were also calculated in a subset of 170 patients.

Results: The average EOA for all BE THV valves (77% Sapien 3) was 2.3 cm2 ± 0.5, while the average EOA was 1.6 ± 0.2 cm2 for 20 mm, 2.0 ± 0.2 cm2 for 23 mm, 2.5 ± 0.3 cm2 for 26 mm and 3.0 ± 0.3 cm2 for 29 mm THV size (p<0.001). Bland-Altman analysis demonstrated very good agreement between EOA and GOA3D (bias -0.04 ± 0.15 cm2). There was a strong correlation between annular area and TEE-based EOA (R=0.84) and GOA3D (R=0.87). The mean performance index was 47 ± 5% and was similar for all THV sizes (p=0.21). EOAs based on TTE were smaller compared to TEE, while the correlation with annular area (R=0.67) and agreement with GOA3D (bias -0.26 ± 0.43 cm2) was not as strong. The overall PPM rate was 2% in the TEE cohort and 12% in the TTE cohort.

Conclusions: Effective orifice areas for BE THVs based on intra-procedural Doppler and 3D-TEE suggest that previously published TTE-based reference values for EOA are underestimated while PPM rates may be overestimated. Our findings have important clinical implications for pre-implant decision making and for the evaluation of THV hemodynamics and function during follow-up.

Keywords: effective orifice area; patient-prosthesis mismatch; transcatheter aortic valve implantation; transcatheter heart valve; transesophageal echocardiography.