Abstract 3557: Reduction of Functional Mitral Regurgitation is Associated with Improving Inferior Myocardial Systolic Function with Low-dose Dobutamine in Patients with Dilated Cardiomyopathy Assessed by Tissue Doppler Echocardiography
Background: It has been shown that functional mitral regurgitation (MR) was associated with mitral annular enlargement, leaflet tethering, and left ventricular (LV) dilatation, sphericalization, and dysfunction. However, the quantitative evaluation of relationship between functional MR and regional myocardial function has not been done. Dobutamine has been known to have the ability to decrease MR volume, but mechanism for beneficial effects of dobutamine has not been clarified. The purpose of this study was to investigate whether improving regional myocardial function with low-dose dobutamine might affect functional MR assessed by tissue Doppler echocardiography.
Methods: We studied 17 patients with reduced LV ejection fraction (34+/-9.8%) secondary to ischemic or nonischemic cardiomyopathy, and MR. Standard 2-dimensional echocardiography was performed and apical 4-chamber, 2-chamber and long-axis views were recorded with tissue Doppler imaging at rest and during dobutamine infusion (10μg/kg/min). We obtained LV ejection fraction, MR volume fraction, tenting area of mitral valve (enclosed between the annular plane and leaflets on the 4-chamber view) and, as indices of regional myocardial function, LV longitudinal peak systolic strain rate (Ssr; absolute value) in the anterior, anteroseptal, posteroseptal, inferior, posterior and lateral segments at the mid-ventricular level.
Results: Dobutamine increased heart rate, systolic blood pressure, LV ejection fraction and Ssr in all segments, and decreased tenting area and MR volume fraction. The decrease in MR volume fraction with dobutamine showed a significant correlation with decrease in tenting area (r=0.77, p<0.005). And the decrease in tenting area with dobutamine had a good correlation with increase in Ssr in the inferior segment (r=0.61, p<0.01), but neither increase in Ssr in the anterior, anteroseptal, posteroseptal, posterior nor lateral segment. Furthermore, the decrease in MR volume fraction was correlated with increase in Ssr in the inferior segment (r=0.61, p<0.01).
Conclusions: The results of this study suggest that inferior myocardial systolic function may affect the configuration of mitral apparatus and may be one of the determinants of functional MR severity.