Implications of Asymmetry and Valvular Morphotype on Echocardiographic Measurements of the Aortic Root in Bicuspid Aortic Valve

Background: Transthoracic echocardiography (TTE) and magnetic resonance imaging (MRI) have yielded excellent results in aortic root diameter measurement in patients with tricuspid aortic valve. However, accuracy in bicuspid aortic valve (BAV), often associated with aortic root asymmetry, is not fully defined. The aim of this study was to determine the agreement between TTE and MRI in proximal ascending aortic diameters in patients with BAVs. Methods: Seventy-six consecutive patients with BAVs (mean age, 53 +/- 15 years; 65% men) who underwent both TTE and MRI for ascending aortic assessment in a follow-up protocol were included in the study. Maximum aortic root and ascending aortic diameters were compared. Results: For the whole population, TTE slightly underestimated aortic root diameter (difference, -0.8 +/- 2.9 mm; P = .02). However, agreement was significantly better in BAV with fusion of the left and right coronary cusps than with fusion of the right coronary and noncoronary cusps, both with (type 1) and without (type 0) raphe (mean difference, 0.1 +/- 2.5 vs -2.8 +/- 2.8 mm, P < .001, respectively). In raphe BAV, mean absolute differences of maximum diameters between both techniques were significantly greater in asymmetric versus symmetric aortic roots (3.3 +/- 2.2 vs 1.6 +/- 1.9 mm, P = .002). BAV type and root asymmetry were independent related to measurement disagreement between both modalities. Conclusions: Although TTE is the technique of choice in the follow-up of patients with BAVs, aortic root diameter measurements may be inaccurate in the presence of root asymmetry and in BAV with fusion of the right coronary and noncoronary cusps. In these cases, cross-sectional imaging, with MRI or computed tomography, to confirm aortic diameters may be advisable.