INTRAMURAL MECHANICS IN HYPERTROPHIC CARDIOMYOPATHY - FUNCTIONAL MAPPING WITH STRAIN-RATE MR-IMAGING

PURPOSE: To characterize systolic and diastolic intramural mechanics i n hypertrophic cardiomyopathy (HCM) with a new metric of contractile a ctivity. MATERIALS AND METHODS: Eleven healthy subjects and eight pati ents with HCM underwent velocity-encoded echo-planar magnetic resonanc e (MR) imaging (6-8-frame gated breath-hold movies, 3 x 3-mm resolutio n). A scalar strain rate (SR) parameter was compared with wall thickne ss and symptoms. RESULTS: The normal pattern of SR included regional u niformity, a monotonically increasing subepicardial to subendocardial gradient, and minimum transmural shear rate. In HCM, heterogeneity of SRs increased in diastole. Regional diastolic SR correlated with regio nal wall thickness (r = .785, P = .0001). Interobserver global SR assi gnment agreed in seven of eight patients. All four patients with New Y ork Heart Association class 1 disease had a low global SR deficit scor e, whereas three of four patients with class 2 or 3 disease had a high SR deficit score (Spearman r = .775, P = .187). CONCLUSION: SR charac terization may provide an objective measure of disease course in HCM.