Quantification of Significant Aortic Stenosis by Echocardiography versus Four-Dimensional Cardiac Computed...

Area of Science:

• Cardiology
• Medical Imaging

Background:

• Transthoracic echocardiography (TTE) grading of aortic stenosis (AS) can be challenging with discrepant parameters.
• Four-dimensional cardiac computed tomography (4D-CCT) is increasingly used for transcatheter intervention workup.

Purpose of the Study:

• To compare transthoracic echocardiography (TTE) and 4D-CCT measures for quantifying aortic stenosis (AS).
• To assess the impact of 4D-CCT on AS subtype classification.

Main Methods:

• Retrospective study of 80 AS patients (mean age 86 ± 10 years) referred for transcatheter aortic valve replacement.
• Correlation and Bland-Altman analyses between TTE and 4D-CCT parameters including left ventricular volumes, function, mass, outflow tract dimensions, and aortic valve area (AVA).
• Patients categorized into high-gradient AS (HG-AS), classical and paradoxical low-flow low-gradient AS (CLFLG-AS and PLFLG-AS), and normal-flow low-gradient AS (NFLG-AS).

Main Results:

• Moderate-to-high correlations (r = 0.51–0.88) between TTE and 4D-CCT for left ventricular parameters, with significantly higher values by 4D-CCT (p < 0.001).
• TTE estimates of aortic valve area (AVA) showed modest correlation (r = 0.37–0.43) with 4D-CCT planimetry but were significantly lower (by 0.15–0.32 cm²).
• 4D-CCT left ventricular stroke volume index (LVSVi) led to significant reclassification of AS subtypes compared to TTE.

Conclusions:

• 4D-CCT quantifies higher values for the left ventricle and aortic valve area (AVA) than TTE in AS patients.
• 4D-CCT-derived LVSVi can reclassify AS subtypes, indicating potential clinical implications for severe AS management.
• Further research is warranted to establish the clinical implications and optimal thresholds for 4D-CCT in severe AS management.