Differential Left Ventricular Outflow Tract Remodeling and Dynamics in Aortic Stenosis

• Published in: Journal of the American Society of Echocardiography Vol. 28; no. 11; pp. 1259 - 1266
• Main Authors: Mehrotra, Praveen, Flynn, Aidan W., Jansen, Katrijn, Tan, Timothy C., Mak, Gary, Julien, Howard M., Zeng, Xin, Picard, Michael H., Passeri, Jonathan J., Hung, Judy
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2015
• Subjects: Aged, 80 and over; Aortic stenosis; Aortic Valve Stenosis - complications; Aortic Valve Stenosis - diagnostic imaging; Cardiovascular; Diagnosis, Differential; Dynamics; Echocardiography, Three-Dimensional - methods; Elasticity Imaging Techniques - methods; Female; Heart Ventricles - diagnostic imaging; Humans; Image Interpretation, Computer-Assisted - methods; Left ventricular outflow tract; Male; Middle Aged; Reproducibility of Results; Sensitivity and Specificity; Severity of Illness Index; Stiffness; Three-dimensional echocardiography; Ventricular Outflow Obstruction - diagnostic imaging; Ventricular Outflow Obstruction - etiology; Ventricular Remodeling; Aortic stenosis; EI; TTE; Three-dimensional echocardiography; AVA; LVOT; CSA; 3D; AS; 2D; Dynamics; TEE; Stiffness; Left ventricular outflow tract; DC; Transesophageal echocardiography; Cross-sectional area; Transthoracic echocardiography; Distensibility coefficient; Two-dimensional; Three-dimensional; Ellipticity index; Aortic valve area
• DOI: 10.1016/j.echo.2015.07.018
• ISSN: 0894-7317; 1097-6795

Left ventricular outflow tract (LVOT) geometry is variable and often elliptical, which can affect aortic valve area calculation in patients with aortic stenosis (AS). Specific differences in LVOT geometry and dynamics between patients with AS and normal control subjects have not been described. The aim of this study was to test the hypothesis that differences in LVOT geometry in patients with AS might relate to variable LVOT remodeling and stiffness relative to normal control subjects. In 54 patients with severe AS and 33 control subjects without AS, LVOT geometry, dynamics, remodeling, and stiffness were assessed by three-dimensional transesophageal echocardiography. LVOT stiffness was measured by calculating the distensibility coefficient, defined as the percentage change in LVOT area relative to change in left ventricular pressure. LVOT remodeling was assessed by measuring the posterior LVOT wall thickness. Multivariate linear regression analysis was used to determine independent associations with peak systolic LVOT ellipticity. LVOT area by three-dimensional transesophageal echocardiographic planimetry was compared with areas obtained assuming circular or elliptical geometry. At end-diastole, LVOT geometry was similar between patients with AS and normal control subjects. In patients with AS, however, the percentage change in cross-sectional area (7.5% vs 14.7%, P < .001) from end-diastole to peak systole was lower compared with normal control subjects, while peak systolic ellipticity index was higher in patients with AS (1.18 vs 1.08, P < .001). Compared with control subjects, patients with AS had lower distensibility coefficients (4.7 ± 1.9 × 104 vs 12.5 ± 5.3 × 104 mm Hg−1, P < .001) and higher posterior LVOT wall thickness (3.5 ± 0.8 vs 2.3 ± 0.5 mm, P < .001). In multivariate analysis, posterior LVOT wall thickness and distensibility coefficient were independently associated with peak systolic LVOT ellipticity index. LVOT area underestimation by transthoracic echocardiography was higher in patients with AS when assuming circular geometry (20% vs 12%, P = .001). The LVOT is less distensible and undergoes remodeling in severe AS. These changes lead to greater peak systolic ellipticity and greater LVOT cross-sectional area underestimation relative to normal control subjects. These findings have important implications for the assessment of AS severity.