The change in the left atrial dimension during diastole. Echocardiographic assessment of mitral stenosis.

The change in the left atrial dimension during diastole was examined in patients with mitral stenosis using echocardiography. The left atrial emptying fraction (LAEF), defined as the ratio of enddiastolic dimension to endsystolic dimension of the left atrium, was 0.65 +/- 0.03 (mean +/- SE) for normal subjects, 0.86 +/- 0.01 for low grade mitral stenosis, and 0.92 +/- 0.01 for high grade stenosis. The LAEF correlated well with mitral valve area index (r = -0.70), but the correlation between E-F slope of the anterior mitral leaflet and mitral valve area index was less significant (r = 0.48). In patients who received mitral valve replacement the LAEF and the left atrial dimension significantly improved. The left atrial emptying fraction is an easily obtainable and reliable index to estimate the severity of mitral stenosis, even in patients who have undergone mitral valvular surgery.