Left atrial filling volume can be used to reliably estimate the regurgitant volume in mitral regurgitation

Abstract

Objectives: The objective was to analyze the accuracy and diagnostic value of the estimated regurgitant volume of mitral regurgitation using 1) left atrial volume variation during ventricular systole (left atrial filling volume) and 2) the percent of systolic pulmonary vein velocity integral compared with its total.

Background: Left atrial filling volume (LAfill), which represents the atrial volume variation during ventricular systole, has been used for the assessment of mitral regurgitation severity. A good correlation with invasive semiquantitative evaluation was found, but with an unacceptable overlapping among grades. The reason could be the absence of information concerning the contribution of blood entering into the left atrium from the pulmonary veins.

Methods: Doppler regurgitant volume (Dpl-RVol) (mitral stroke volume - aortic stroke volume) was measured in 30 patients with varying degrees and etiological causes of mitral regurgitation. In each patient atrial volumes were measured from the apical view, using the biplane area-length method. The systolic time-velocity integral of pulmonary vein flow was expressed as a percentage of the total (systolic-diastolic) time-velocity integral (PVs%). These parameters were used in this group of patients to obtain an equation whose reliability in estimating Dpl-RVol was tested in a second group of patients.

Results: In the initial study group, with linear regression analysis the following parameters correlated with Dpl-RVol: end-systolic left atrial volume (R2=0.37, p=0.0004); LAfill (R2=0.45, p < 0.0001); PVs% (R2=0.56, p < 0.0001). In multiple regression analysis the combination of LAfill and the percent of the systolic pulmonary vein velocity integral (PVs%) provided a more accurate estimate of regurgitant volume (R2=0.88; SEE 10.6; p < 0.0001; Dpl-RV=6.18 + (1.01 x LAfill) - (0.783 x PVs%). The equation was subsequently tested in 54 additional patients with mitral regurgitation with a mean Dpl-RVol 27+/-37 ml. Estimated regurgitant volume and Dpl-RVol correlated well with each other (R2=0.90; SEE 12.1; p < 0.0001). In the test population, the equation was 100% sensitive and 98% specific in detecting a regurgitant volume higher than 55 ml.

Conclusions: Left atrial filling volume and pulmonary vein flow give a reliable estimate of regurgitant volume in mitral regurgitation.