[Determination of mitral valve area in patients with mitral stenosis by the flow-convergence method: clinical application].

Background: Classic echocardiographic methods to estimate mitral valve area (MVA) in the mitral stenosis (MS) has several limitations. Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA.
Aims: This study sought to 1) compare the accuracy of the PISA method to planimetry and Doppler pressure half-time (PHT) methods for echocardiographic estimation of MVA and 2) to evaluate the effect of atrial fibrillation (AF) and significant mitral regurgitation (MR) on the accuracy of the PISA method.
Methods: In 35 patients with rheumatic mitral stenosis, the mitral valve areas were determined by two-dimensional echocardiographic planimetry, pressure half-time and proximal flow convergence region. 19 patients had atrial fibrillation and 15 had associated mitral insufficiency > or = 2.
Results: The correlaton between PISA and planimetry areas was significant (r=0.83, p<.001). The intraclass correlation coefficient was of 0.85 but with a large confidence interval (IC 95% [0,68-0,9]) explaining the significant underestimation of MVA by PISA method: 1,42 +/- 0,47 cm2 versus 1,56 +/- 0,41 cm2 respectively, (p<.001). There was no signicant difference between PISA and PHT areas : 1,42 +/- 0,47 cm2 versus 1,43 +/- 0,46 cm2. Underestimation of MVA par PISA method didn't have real clinical implication: the sensibility of diagnosing severe MS (MVA < or = 1.5 cm2) was 90% vith a negative predictive value of 83%. The correlation was good in patients with AF (r=0,84, p<.001) and with significant MR (r=0,83, p<.001).
Conclusion: The PISA method may be considered as reliable alternative method for estimation of the MVA in MS. Its accuracy is good in AF and associated MR.