Validation of methods for effective orifice area measurement of prosthetic valves by two-dimensional and Doppler echocardiography following transcatheter self-expanding aortic valve implantation

Background The effective orifice area(EOA) is utilized to characterize the hemodynamic performance of the transcatheter heart valve(THV). However, there is no consensus on EOA measurement of self-expanding THV. We aimed to compare two echocardiographic methods for EOA measurement following transcatheter self-expanding aortic valve implantation. Methods EOA was calculated according to the continuity equation. Two methods were constructed. In Method 1 and Method 2, the left ventricular outflow tract diameter(LVOTd) was measured at the entry of the prosthesis(from trailing-to-leading edge) and proximal to the prosthetic valve leaflets(from trailing-toleading edge), respectively. The velocity-time integral(VTI) of the LVOT(VTILVOT) was recorded by pulsed-wave Doppler(PW) from apical windows. The region of the PW sampling should match that of the LVOTd measurement with precise localization. The mean transvalvular pressure gradient(MG) and VTI of THV was measured by Continuous wave Doppler. Results A total of 113 consecutive patients were recruited. The mean age was 77.2 ± 5.5 years, and 72 patients(63.7%) were male. EOA1with the use of Method 1 was larger than EOA2(1.56 ± 0.39 cm2 vs. 1.48 ± 0.41 cm2, P = 0.001). MG correlated better with the indexed EOA1(EOAI1)(r =-0.701, P < 0.001) than EOAI2(r =-0.645, P < 0.001). According to EOAI(EOAI ≤ 0.65 cm2/m2, respectively), the proportion of sever prosthesis-patient mismatch with the use of EOA1was lower than EOA2(12.4% vs. 21.2%, P < 0.05). Compared with EOA2, EOA1had lower interobserver and intra-observer variability(intra: 0.5% ± 17% vs. 3.8% ± 22%, P < 0.001; inter: 1.0% ± 9% vs. 3.5% ± 11%, P < 0.001). Conclusions For transcatheter self-expanding valve EOA measurement, LVOTd should be measured in the entry of the prosthesis stent(from trailing-to-leading edge), and VTILVOT should match that of the LVOTd measurement with precise localization.