Assessment of aortic valve area on cardiac computed tomography in symptomatic bicuspid aortic stenosis: Utility and differences from Doppler echocardiography

BACKGROUND: In this study, we investigate the utility of geometric orifice area (GOA) on cardiac computed tomography (CT) and differences from effective orifice area (EOA) on Doppler echocardiography in patients with bicuspid aortic stenosis (AS). METHODS: A total of 163 patients (age 64 ± 10 years, 56.4% men) with symptomatic bicuspid AS who were referred for surgery and underwent both cardiac CT and echocardiography within 3 months were studied. To calculate the aortic valve area, GOA(CT) was measured by multiplanar CT planimetry, and EOA(Echo) was calculated by the continuity equation with Doppler echocardiography. The relationships between GOA(CT) and EOA(Echo) and patient symptom scale, biomarkers, and left ventricular (LV) functional variables were analyzed. RESULTS: There was a significant but modest correlation between EOA(Echo) and GOA(CT) (r = 0.604, p < 0.001). Both EOA(Echo) and GOA(CT) revealed significant correlations with mean pressure gradient and peak transaortic velocity, and the coefficients were higher in EOA(Echo) than in GOA(CT). EOA(Echo) of 1.05 cm(2) and GOA(CT) of 1.25 cm(2) corresponds to hemodynamic cutoff values for diagnosing severe AS. EOA(Echo) was well correlated with the patient symptom scale and log NT-pro BNP, but GOA(CT) was not. In addition, EOA(Echo) had a higher correlation coefficient with estimated LV filling pressure and LV global longitudinal strain than GOA(CT). CONCLUSION: GOA(CT) can be used to evaluate the severity of bicuspid AS. The threshold for GOA(CT) for diagnosing severe AS should be higher than that for EOA(Echo). However, EOA(Echo) is still the method of choice because EOA(Echo) showed better correlations with clinical and functional variables than GOA(CT).