Abstract 2476: Intraventricular Septal Intramural Asynchrony in Patients with Hypertrophic Cardiomyopathy Using Tissue Velocity Imaging Correlates with the Severity of Myocardial Fibrosis
Background: Hypertrophic cardiomyopathy (HCM) is histologically characterized by myocardial fibrosis and disarray. These myocardial changes may affect timing of regional peak contractions. We investigated whether there was a correlation between intraventricular septal (IVS) intramural asynchrony based on tissue velocity imaging and the histologic changes.
Methods: We obtained apical 4-chamber tissue velocity images in 20 normal subjects and 51 patients with HCM using Vivid 7 (GE). We set 6 regions of interest (ROIs) on the base to 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 disarray in 25 patients with HCM undergoing myocardial biopsy. The degree of myocardial fibrosis and disarray was graded qualitatively (0 to 3 scale) according to the percent of findings occupied of the tissue sample.
Results: Ts-SD was larger in patients with HCM compared with normal subjects (13.12 ms vs. 5.17 ms, p<0.05), suggesting asynchronous contraction of IVS in HCM. Ts-SD showed a significant correlation with the degree of myocardial fibrosis (r=0.75, p<0.05), while not with that of myocardial disarray (r=0.01, p=0.20).
Conclusions: There was intramural asynchrony in IVS in HCM. Assessment of the IVS asynchrony using tissue velocity imaging could predict the degree of myocardial fibrosis noninvasively without biopsy. Because myocardial fibrosis is the substrate for premature deaths in HCM, the present method should provide clinically important information.