BACKGROUND

Angiography and echo-color Doppler imaging are routinely used for the semiquantitative grading of functional mitral regurgitation (MR) in dilated cardiomyopathy. However, in case of severe regurgitation the results obtained using these two methods are discrepant. We propose quantitative echocardiographic evaluation and the related morphological parameters of remodeling of the ventricular and mitral apparatuses for the estimate of severe regurgitation.

METHODS

Fifty-two patients with dilated cardiomyopathy and functional MR (28 males, 24 females, ejection fraction < or = 40%) were evaluated by means of echocardiography for a total of 73 echocardiograms (basal and 21 at the sixth month). The echo measurements included the left ventricular end-diastolic and end-systolic volumes, ejection fraction, area jet/left atrial area, diastolic and systolic mitral annulus areas and fractional contraction (MAC, %), systolic tenting area (TA, cm2, area enclosed between the annular plane and mitral leaflets), systolic tethering length (TL, cm, papillary tips and intervalvular fibrosa distance); quantitative Doppler (using the mitral and aortic stroke volumes) and PISA methods were averaged to calculate the regurgitant volume (RV, ml/beat), regurgitant fraction (RF, %), and effective regurgitant orifice (ERO, mm2).

RESULTS

The strongest correlation with ERO, RV and RF was obtained with systolic TA (beta = 0.40, 0.67 and 0.60; SE 1.68, 1.56 and 1.38; p = 0.01, p = 0.0001 and p = 0.0001, respectively) and MAC (beta = -0.33, -0.61 and -0.61; SE 0.31, 0.31 and 1.49; p = 0.03, p = 0.0001 and p = 0.0001, respectively). We did not find any correlation with ejection fraction (p = NS). The following values were found to be indicative of severe functional MR: ERO > or = 40 mm2, RV > or = 49 ml/beat, RF > or = 57%, MAC < or = 12.5%, TA > or = 7.7 cm2, and TL > or = 4.7 cm.

CONCLUSIONS

We did not find any significant correlation between the quantitative functional MR echo parameters and systolic dysfunction. The major determinants of ERO, RV and RF were the loss of MAC and larger systolic TAs. These parameters are significantly proportional to the severity of functional MR as assessed by the semiquantitative criteria commonly adopted in the clinical practice. We propose the values of ERO, RV, RF, TA, MAC and TL as indicative of severe functional MR.