Multimodality assessment of aortic valve area in aortic stenosis: a multicenter validation study

Transthoracic echocardiography (TTE) is the standard modality for grading aortic stenosis (AS) severity. Transesophageal echocardiography (TOE) allows direct aortic valve area (AVA) planimetry (AVA_TOE), while computed tomography angiography (CTA) offers a non-invasive alternative (AVA_CTA). This study aimed to evaluate the correlation between AVA measurements across modalities and to determine a diagnostic AVA_CTA threshold for severe AS.

This retrospective study included a single-center derivation cohort of 176 patients (mean age 80.0 ± 7.7 years, 52.8% male) with moderate to severe AS who underwent full-cycle CTA, TTE, and TOE. AVA_CTA was measured by two independent raters. Correlation with AVA_TOE and other parameters was assessed. Receiver operating characteristic (ROC) analysis was used to define an optimal AVA_CTA threshold for severe AS, which was validated in a multi-center cohort of 407 patients (mean age 80.9 ± 6.7 years, 52.8% male) with comparable characteristics.

Mean AVA_CTA was 0.96 ± 0.28 cm² with a high interrater reliability (IRR = 0.84), compared to a mean AVA_TOE of 0.88 ± 0.26 cm² (Pearson's r = 0.73). ROC analysis identified 0.96 cm² as the optimal AVA_CTA threshold for diagnosing severe AS (AUC = 0.846; sensitivity = 71.7%; specificity = 89.8%) compared to TOE grading. This threshold yielded good diagnostic performance in the validation cohort (AUC = 0.817; sensitivity = 78.2%; specificity = 72.6%).

AVA_CTA demonstrated high reliability, showing a strong correlation with AVA_TOE. The 0.96 cm² threshold, defined in the derivation cohort, performed well in the validation cohort for assessing aortic stenosis severity.