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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-to-leading edge),respectively.The velocity-time integral(VTI)of the LVOT(VTILVOT)was recorded by pulsed-wave Doppler(PW)from api-cal windows.The region of the PW sampling should match that of the LVOTd measurement with precise localization.The mean transvalvu-lar 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.EOA1 with 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 EOA1 was lower than EOA2(12.4％vs.21.2％,P ＜ 0.05).Compared with EOA2,EOA1 had 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.