Comparison of echocardiography and CT angiography for measurement of aortic annulus diameters before transcatheter aortic valve implantation

Abstract

Accurate assessment of the aortic annulus diameter is crucial for successful transcather aortic valve implantation (TAVI). We compared the aortic annulus diameter obtained by echocardiography and computed tomography (CT) angiography in patients referred for TAVI. On echo, the aortic annulus diameter was measured from parasternal long axis view in systole. An average of two measurements was calculated. On CT, the annulus was measured in cross-sectional view (perpendicular to the flow axis). Three diameters were obtained; maximum ( Dmax ), minimum ( Dmin ) and the mean ( Dmean ) (from cross-sectional area (CSA)) diameters ( Fig. 1 ). The echo and CT measurements were performed independently. The degree of agreement was assessed by Bland-Altman plot. Twenty-eight patients (mean age 76 ± 8 years, males were 21) with severe symptomatic aortic stenosis comprised the study population. The aortic annulus diameters were 22 ± 1.4 mm on echo and 26.6 ± 2.8 mm, 20.4 ± 1.9 mm and 23.5 ± 1.9 mm on CT Dmax , Dmin and Dmean , respectively. Regardless of the CT method, there was good agreement between the echo and CT measure of aortic annulus. The mean diameter obtained from CSA of the CT angiography had the least difference and the narrowest limit of agreement with the ECHO-measured aortic valve annulus diameter ( Fig. 2 ). Echo and CT measurements of aortic annulus were close but not identical, possibly due to the complex 3-dimensional structure and elliptical shape of the aortic annulus. Our findings on echo measurements provided good results compared to the mean diameter obtained by CT angiography.