Comparison of 64-slice computed tomography planimetry and Doppler echocardiography in the assessment of aortic valve stenosis

Background and aim of the study: The study aim was to compare, prospectively, the planimetry of aortic stenosis on 64-slice computed tomography (CT), with the area calculated by Doppler transthoracic echocardiography (TTE) in symptomatic patients evaluated before potential aortic valve replacement. Methods: Fifty-two consecutive patients (27 males, 25 females; mean age 74 ± 10 years) admitted to the authors' institution during 2005 were evaluated with 64-slice CT and Doppler TTE. The time interval between the two evaluations was 2 ± 1 weeks. Planimetry of the anatomic orifice area (AOA) drawn on 64-slice CT was compared to the effective area determined by Doppler TTE by Bland and Altman analysis, and the anatomic area threshold value corresponding to a significant effective aortic stenosis (≤0.75 cm²) was determined by receiver operating characteristic (ROC) analysis. Results: The aortic orifice area measured by 64-slice CT correlated well with the effective area (r = 0.76; p <0.0001), but was significantly greater, with a systematic overestimation (0.132 cm²) and a variability of 0.239 cm². There was good agreement between planimetry determined by two independent radiologists (difference = 0.002, variability = 0.115 cm²). ROC analysis showed that a threshold value of 0.95 cm² as measured by 64-slice CT planimetry identifies significant aortic stenosis with sensitivity, specificity, accuracy, positive and negative predictive values of 82%, 77%, 81%, 91% and 59%, respectively. Conclusion: 64-slice CT is a reproducible and reliable non-invasive method to evaluate aortic valve stenosis compared to the reference method of Doppler TTE. Indeed, the CT approach could replace the latter evaluation when measurements used in the continuity equation are inadequate.