Two-dimensional and Doppler echocardiography have been widely used for noninvasive determination of valve area in patients with mitral stenosis. Recent studies have indicated that the Doppler-echocardiographic pressure half-time method (PHT) does not accurately predict mitral orifice area (MOA). Therefore, applications of the continuity equation and the Gorlin formula have been used additionally to the PHT for Doppler-echocardiographic assessment of MOA. In a prospective study of 34 patients MOA determined by two-dimensional and Doppler echocardiography was compared with MOA measured by cardiac catheterization (range 0.40 to 1.90 cm2, mean 1.08 +/- 0.37 cm2). There was a moderate correlation between two-dimensional echocardiographic and invasive measurements (r = 0.65, SEE = 0.20 cm2). MOA calculated by the PHT showed only poor correlation with cardiac catheterization (r = 0.38 SEE = 0.37 cm2). We found better correlations for the continuity equation (r = 0.73, SEE = 0.35 cm2) and Doppler-echocardiographic application of the Gorlin formula (r = 0.81, SEe = 0.27 cm2). Doppler-echocardiographic use of the Gorlin formula yielded the best prediction of the severity of mitral valve stenosis (concordance with invasive measurement in 82%).
Conclusion: Pressure half-time is only a poor predictor of the severity of mitral valve stenosis. More accurate results are obtained by Doppler-echocardiographic applications of the continuity equation and especially the Gorlin formula.