Indexed aortic valve area using multimodality imaging for assessing the severity of bicuspid aortic stenosis

Background: The impact of various imaging modalities on discordance/concordance between indexed aortic valve area (iAVA) and catheterization-derived mean transaortic pressure gradient (mPG_cath) is unclear in patients with bicuspid aortic valve (BAV). This study aimed to compare iAVA measurements obtained using four different methodologies in BAV and tricuspid aortic valve (TAV) patients, using mPG_cath as a reference standard.

Methods: We retrospectively reviewed patients who underwent comprehensive assessment of AS, including two-dimensional (2D) transthoracic echocardiography (TTE), three-dimensional (3D) transesophageal echocardiography (TEE), multidetector computed tomography (MDCT), and catheterization, at our institution between 2019 and 2022. iAVA was measured using the continuity eq. (CE) with left ventricular outflow tract area obtained by 2D TTE, 3D TEE, and MDCT, as well as planimetric 3D TEE.

Results and conclusions: Among 564 patients (64 with BAV and 500 with TAV), 64 propensity-matched pairs of patients with BAV and TAV were analyzed. iAVA_CE(2DTTE) led to overestimation of AS severity (BAV, 23.4%; TAV, 28.1%) and iAVA_CE(MDCT) led to underestimation of AS severity (BAV, 29.3%; TAV, 16.7%), whereas iAVA_CE(3DTEE) and iAVA_Plani(3DTEE) resulted in a reduction in the discordance of AS grading. A moderate correlation was observed between mPG_cath and iAVA_CE(3DTEE) (BAV, r = -0.63; TAV, r = -0.68), with iAVA_CE(3DTEE) corresponding to the current guidelines' cutoff value (BAV, 0.58 cm²/m²; TAV, 0.60 cm²/m²). Discordance/concordance between iAVA and mPG_cath in evaluating AS severity varies depending on the methodology and imaging modality used. The use of iAVA_CE(3DTEE) is valuable for reconciling the discordant AS grading in BAV patients as well as TAV.