Measurement of the aortic annulus diameter using transesophageal echocardiography and multislice computed tomography--are they truly comparable?

BACKGROUND: For transcatheter aortic valve implantation (TAVI), transesophageal echocardiography (TEE) and multislice computed tomography (MSCT) measurements of the aortic annulus diameter (AAD) are often regarded as competitive. We evaluated if 1 MSCT method could be interchangeable with TEE measurements.

METHODS: We compared AAD measurements performed using TEE, MSCT, and transthoracic echocardiography (TTE) in 129 consecutive patients with severe aortic stenosis (AS) who were referred for TAVI. Using MSCT, AAD was measured in the 3-chamber (3C) view and at the level of the virtual basal ring (mean diameter [MD] of the long-axis [LA] and short-axis [SA] diameters, and AAD derived from the cross-sectional area [CSA] and the circumference). Correlations with echocardiographic measurements and agreement regarding the TAVI strategy (decision to implant and choice of prosthesis size based on manufacturer cutoff recommendations) were assessed.

RESULTS: AAD measured in 3C (intraclass correlation [ICC], 0.79) and MD emphasizing the weight of the SA (MD4 [3 SA + LA/4]; ICC, 0.76) and MD5 [4 SA + LA/5; ICC, 0.75]) provided the highest correlation and the best agreement with TEE (kappa = 0.47, 0.27, and 0.31 respectively). However, TTE provided a better a correlation and agreement with TEE than all MSCT methods (ICC, 0.87; kappa = 0.66). The agreement between MSCT and TEE varied with AAD eccentricity and degree of aortic valve calcification (AVC), but in all subsets, values observed with MSCT never reached those observed with TTE.

CONCLUSIONS: MSCT and TEE are measuring different landmarks and consequently MSCT and TEE measurements are not interchangeable. Prospective randomized studies aimed at defining which method provides the best clinical results are clearly needed.