Abstract 3736: The Relationship between the Grade of Mitral Regurgitation and Left Ventricular Mechanical Dyssynchrony in the Patients of Dilated Cardiomyopathy
Backgrounds: Functional mitral regurgitation (MR) is common in patients with dilated cardiomyopathy (DCM). Intraventricular dyssynchrony may play a role in the development of MR in DCM.
Methods: We performed tissue Doppler echocardiography in 20 DCM patients to assess left ventricular (LV) dyssynchrony. The LV dyssynchorny was determined the time difference from the onset of the QRS complex to the peak systolic myocardial strain (Ts) in the 6-basal and 6-mid segments from the apical 4-chamber, 2-chamber and long-axis views (iE33, Philips Medical System). The standard deviation of Ts (Ts-SD) of the 12 LV segments was calculated in each patient. The LV end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) were measured by the modified biplane Simpson’s method. Severity of MR was semi-quantitatively assessed (0~3+) by the color Doppler imaging.
Results: There were no differences in EF (38±10 vs. 42±8%, p=0.36), EDV (134±56 vs. 104±21 ml, p=0.20) and ESV (86±45 vs. 61±21 ml, p=0.20) between 12 patients with moderate or severe MR (group A) and 8 patients with trivial MR (group B). The mechanical time delay between basal lateral and basal septal segments was significantly increased in group A compared to that in group B (166±129 vs. 9±33msec, p=0.008). The mechanical time delay between mid lateral and mid septal segments was also significantly increased in group A than in group B (168±131 vs. 4±71 msec, p=0.01: respectively). Ts-SD was also increased in group A than in group B (109±95 vs. 25±19 msec, p=0.02; respectively).
Conclusions: Dyssynchrony of myocardial segments may disturb synergistic closure of the mitral leaflets and causes MR in DCM.