Extrapolation of CT aortic annulus derived diameter/CT aortic annulus area from 2D echocardiography aortic annulus diameter in TAVR: not a reliable tool

Funding Acknowledgements Type of funding sources: None. Background Computed tomography (CT) aortic annulus area, CT area derived diameter and two-dimensional echocardiography (2D ECHO) diameters are used for valvular sizing in transcutaneous aortic valve replacement (TAVR). According to our previous study, 2D ECHO annulus diameter was smaller in comparison to CT derived diameter (22.6±2.9 vs 25.0±5.5mm, p = 0.013), but both CT aortic annulus area derived diameter/CT aortic annulus and 2D ECHO diameter predicted correct valve size selection with the same accuracy of 79–80%. However, CT requires radiation and iodine contrast administration, which might be the limitation in patients with chronic kidney disease or history of iodine allergy. Purpose To determine if 2D ECHO diameter can be used for reliable estimation of CT area derived diameter/CT aortic annulus area. Methods 139 consecutive patients with favourable outcome of Sapien XT/Sapien S3 TAVR (no more than mild aortic regurgitation, only one valve implanted) were included in the study. 2D ECHO diameter was measured from mid oesophageal three-chamber view (110–135°) just below the anatomical aortic valve annulus. CT aortic annulus was obtained as double oblique plane by manual multiplanar reconstruction of CT dataset, defined by three lowest attachment points of valvular leaflets. Aortic annulus area was measured by manual tracking of lumen contours, area derived diameter as 2*√(area/π). Linear regression analysis between pre-implant CT area derived diameter and 2D ECHO diameter was performed; extrapolated CT annulus area diameter and CT aortic annulus area [π*(d/2)2] were calculated from 2D ECHO diameter. Concordance of valve size selection based on extrapolated CT area derived diameter vs original CT area derived diameter and extrapolated CT aortic annulus area vs original CT aortic annulus area was determined on patients where CT aortic annulus area/annulus derived diameter were falling outside the overlap of the manufacturer recommended ranges for neighbouring valve sizes. Results Significant relationship between CT aera derived diameter and 2D ECHO diameter was found (r=0.720, p<0.001, Fig 1,2). Extrapolated CT area derived diameter would have led to inappropriate size selection in 33/100 more cases (undersizing in 16%, oversizing in 17%), similar to extrapolated aortic annulus area, where both undersizing and oversizing was observed in 18/106 (17%) more cases in comparison to original CT based parameters. Conclusion Extrapolation of CT aortic annulus area/area derived diameter from 2D ECHO diameter is not a reliable tool in valvular sizing for balloon expandable Sapien valve. In patients with chronic kidney disease or history of iodine allergy, three-dimensional (3D) ECHO aortic annulus assessment remains the only viable alternative tool.