Accuracy of aortic stenosis severity assessment by Doppler echocardiography: importance of image quality

The aim of the present study was to investigate which factors could influence the accuracy of aortic stenosis severity assessment by Doppler echocardiography in an unselected population. Doppler echocardiographic determination of mean transvalvular pressure gradient and aortic valve area by continuity equation was performed in 101 patients before catheterization. According to the catheterization data, aortic stenosis was classified into 2 categories: mild to moderate (orifice area [Gorlin formula] > 0.75 cm2, mean transvalvular gradient < 50 mmHg) and severe (orifice area < or = 0.75 cm2, mean transvalvular gradient > or = 50 mmHg). The influence of eight factors on the absolute difference in aortic valve area and mean transvalvular pressure gradient and on the concordant classification in the same category by both methods was investigated.

By multivariate analysis, the absolute difference in aortic valve area by both methods was significantly associated with poor image quality, absolute difference between mean catheterization and Doppler transvalvular gradient and inversely related to body mass index. Absolute difference in mean transvalvular gradients by both methods was significantly associated only with image quality. Poor image quality emerged as the only significant factor influencing the concordant classification between invasive and noninvasive studies according to orifice area (but not according to transvalvular pressure gradient).

Echographic image quality significantly influences the accuracy of Doppler echocardiographic determination of aortic valve area and, to a lesser extent, of transvalvular pressure gradient. Therefore, the mere noninvasive approach is not suitable to every consecutive patient with aortic stenosis. Qualifications concerning overall image quality should identify patients most likely to benefit from catheterization.