Dilated cardiomyopathy (DCM) is histologically characterized by myocardial fibrosis and cellular hypertrophy. These myocardial changes may affect timing of regional peak contraction. We investigated whether there was a correlation between intraventricular septal (IVS) intramural asynchrony based on tissue velocity imaging and the histologic changes. We obtained apical 4-chamber tissue velocity images in 27 normal subjects and 22 patients with DCM undergoing myocardial biopsy using Vivid 7 (GE). We set 6 tandem regions of interest (ROIs) on the mid level of the IVS and measured the time to peak myocardial contraction (Ts) from the QRS onset at each ROI. We defined the standard deviation of Ts (Ts-SD) as an index of IVS asynchrony. Further, we analyzed a correlation between Ts-SD and the degree of myocardial fibrosis and cellular hypertrophy. The degree of myocardial fibrosis and cellular hypertrophy was graded qualitatively (0 to 3 scale) according to the percent of fibrosis occupied of the tissue sample and cell size. Ts-SD was larger in patients with DCM compared with normal subjects (13.9±12.3 vs. 6.2±4.0 ms, p<0.05), suggesting asynchronous contraction of IVS in DCM. Ts-SD showed a significant correlation with the degree of myocardial fibrosis (grade 1, 6.9±3.5 ms; grade 2, 15.7±3.5 ms; grade 3, 25.9±5.3 ms; p<0.05), while not with that of cellular hypertrophy (p=0.50). There was intramural asynchrony in IVS in DCM. This method could predict the degree of myocardial fibrosis noninvasively. Because myocardial fibrosis is the substrate for heart failure in DCM, the present method should provide clinically important information.
A Case of Dilated Cardiomyopathy: Worsening Myocardial Fibrosis and Cardiac Reversibility After Withdrawal of Medical Treatment
