Effect of the ellipsoid shape of the left ventricular outflow tract on the echocardiographic assessment of aortic valve area in aortic stenosis.
BACKGROUND
Previous studies showed discrepancies between echocardiographic and multidector row CT (MDCT) measurements of aortic valve area (AVA).


OBJECTIVE
Our aim was to evaluate the effect of the ellipsoid shape of the left ventricular outflow tract (LVOT), as shown and measured by MDCT, on the assessment of AVA by transthoracic echocardiography (TTE) in patients with severe aortic stenosis.


METHODS
This retrospective single-center study involved 49 patients with severe aortic stenosis referred before transcatheter aortic valve implantation. The AVA was deduced from the continuity equation on TTE and from planimetry on cardiac MDCT. Area of the LVOT was calculated as follows: on TTE, from the measurement of LVOT diameter on parasternal long-axis view; on MDCT, from manual planimetry by using multiplanar reconstruction perpendicular to LVOT.


RESULTS
At baseline, correlation of TTE vs MDCT AVA measurements was moderate (R = 0.622; P < .001). TTE underestimated AVA compared with MDCT (0.66 ± 0.15 cm2 vs. 0.87 ± 0.15 cm2; P < .001). After correcting the continuity equation with the LVOT area as measured by MDCT, mean AVA drawn from TTE did not differ from MDCT (0.86 ± 0.2 cm2) and correlation between TTE and MDCT measurements increased (R = 0.704; P < .001).


CONCLUSION
Assuming that LVOT area is circular with TTE results in constant underestimation of the AVA with the continuity equation compared with MDCT planimetry. The elliptical not circular shape of LVOT largely explains these discrepancies.
['De Vecchi|Clément|C|', 'Caudron|Jérôme|J|', 'Dubourg|Benjamin|B|', 'Pirot|Nathalie|N|', 'Lefebvre|Valentin|V|', 'Bauer|Fabrice|F|', 'Eltchaninoff|Hélène|H|', 'Dacher|Jean-Nicolas|JN|']
D000369:Aged, 80 and over D001021:Aortic Valve D001024:Aortic Valve Stenosis D004452:Echocardiography D005260:Female D006801:Humans D007089:Image Enhancement D007090:Image Interpretation, Computer-Assisted D008297:Male D061330:Multidetector Computed Tomography D015203:Reproducibility of Results D012680:Sensitivity and Specificity D014694:Ventricular Outflow Obstruction
Left ventricular outflow tract Aortic stenosis MDCT Transthoracic echocardiography Continuity equation