Orifice Areas of Balloon-Expandable Transcatheter Heart Valves: A Three-Dimensional Transesophageal Echocardiographic Study

Abstract

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 on the basis of Doppler and three-dimensional (3D) transesophageal echocardiography (TEE). Two hundred twelve intraprocedural transesophageal echocardiographic examinations performed during BE THV implantation with optimal postimplantation Doppler and 3D imaging were retrospectively reviewed. Continuity equation-derived EOAs were compared with geometric orifice areas by 3D planimetry (GOA3D). Performance indices (i.e., EOA normalized to valve size) and PPM rates were determined. TTE-based EOAs obtained within 30days were also calculated in a subset of 170 patients. The average EOA for all BE THV valves (77% SAPIEN 3) was 2.3±0.5cm2, while the average EOA was 1.6±0.2cm2 for 20-mm, 2.0±0.2cm2, for 23-mm, 2.5±0.3cm2 for 26-mm, and 3.0±0.3cm2 for 29-mm THV size (P<.001). Bland-Altman analysis demonstrated very good agreement between EOA and GOA3D (bias -0.04±0.15cm2). There were strong correlations 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=.21). EOAs based on TTE were smaller compared with those based on TEE, while the correlation with annular area (R=0.67) and agreement with GOA3D (bias -0.26±0.43cm2) was not as strong. The overall PPM rate was 2% in the TEE cohort and 12% in the TTE cohort. EOAs for BE THVs based on intraprocedural 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 preimplantation decision-making and for the evaluation of THV hemodynamics and function during follow-up.