Rofo 2012; 184 - KLA04
DOI: 10.1055/s-0031-1300885

Aortic Annulus Dimensions in Patients Evaluated for TAVI: Comparison of Multiplanar Measurement in Computed Tomography to Transesophageal Echocardiography

D Bittner 1, S Gauss 1, M Marwan 1, M Arnold 1, S Ensminger 1, G Muschiol 1, D Ropers 1, S Loders 1, A Schuhbäck 1, T Pflederer 1, WG Daniel 1, J Min 2, J Leipsic 3, S Achenbach 1
  • 1Universitätsklinikum Erlangen, Medizinische Klinik 2, Erlangen
  • 2Weill Cornell Medical College, Division of cardiology, New York
  • 3University of British Columbia, Division of Cardiology, Vancouver

Introduction:

Transcatheter aortic valve implantation (TAVI) is an increasingly used treatment option for patients with severe aortic valve stenosis but high risk of conventional surgery. Prosthesis sizing is critical for procedural success. The size of the aortic annulus in echocardiography is routinely used for prosthesis sizing, but CT can provide accurate visualization of the aortic valve apparatus and may be a better modality to determine its dimensions. However, the correlation of CT-based measures of the aortic annulus to echocardiography is not well known.

Methods:

86 patients scheduled for TAVI were investigated by contrast-enhanced dual source CT (high pitch spiral acquisition –120kV, 320mAs, 0.28s gantry rotation, collimation 2×128×0.6mm, pitch 3.4, triggered at 60% of the R-R interval). Aortic annulus width was determined in CT in two multiplanar reconstructions corresponding to a 3-chamber view and a left ventricular short axis view. Eccentricity was determined by dividing the larger by the smaller value. The mean of the two widths was considered to represent the aortic annulus diameter and was compared to transesophageal echocardiography (TEE).

Results:

The patient group comprised 42 male and 44 female individuals with a mean age of 82±6 years and a mean Euroscore of 33.6±13.3. The mean eccentricity of the aortic annulus in CT was 1.2±0.1, with a mean smaller width of 21.9±2.3mm versus larger width of 25.5±2.6mm (p<0.001). The mean annulus diameter in CT was 23.7±2.2mm. The mean TEE-derived diameter was 22.3±1.8mm. Correlation between CT and TEE was moderate (r=0.65) with a mean absolute difference of 1.7±1.4mm. Bland Altman analysis revealed a bias of +1.4mm (see figure).

Conclusion:

CT demonstrates substantial eccentricity of the aortic annulus in patients evaluated for TAVI. It is important to consider that dimensions of the aortic annulus as derived from two multiplanar measurements in CT do not correlate closely to TEE, since small deviations in measuring the aortic annulus can lead to substantial problems related to inaccurate prosthesis sizing. With the described method, CT typically overestimates the size of the aortic annulus as compared to TEE.