Aims: Mitral regurgitation (MR) is common and independently predicts mortality in patients with left ventricular (LV) systolic dysfunction. Its management remains challenging because of the complexity and variety of potential mechanisms implicated. We sought to determine which LV functional characteristics are the most important determinants of the severity of the MR associated with dilated cardiomyopathies.
Methods and results: We performed echocardiographic studies in 87 consecutive patients with dilated cardiomyopathy. The degree of MR was quantified according to guidelines. LV, left atrial and mitral annulus dimensions, mitral valve tenting, estimated filling pressures, regional myocardial contractility, and dyssynchrony (using regional strain (epsilon) analysis) were recorded too. Determinants of significant MR was thus assessed using multivariate models. Mitral regurgitant volume correlated with mitral annulus diameter (P<0.001), mitral valve tenting height (P<0.001), LV volumes (P=0.004), LV ejection fraction, mid-lateral wall peak of epsilon (P=0.01), and its delay (P<0.001). That inter-relation between the mitral annulus, the ventricle shape, contractility, and dyssynchrony was founded in the multivariate analysis. As a matter of fact, the model predicting the best the MR volume (R=0.78) included: mitral annulus diameter, dyssynchrony, tenting heigh and contractility of the LV mid-lateral wall (measured by epsilon).
Conclusion: The MR of the dilated cardiomyopathy is multifactorial. Our data suggest that analysing only LV geometry and mitral orifice is insufficient to correctly describe functional MR determinant. LV contractility and dyssynchrony are essential too.