Hypertrophic cardiomyopathy (HCM) is a disease that typically has heterogeneous 
hypertrophy and dysfunction of the myocardium. Cardiac magnetic resonance 
imaging (CMR) can be used to accurately assess ventricular wall thickness and 
regional fibrosis. We investigated the effects of hypertrophy and fibrosis on 
the heterogeneity of regional and global myocardial function in HCM. Forty 
patients who were diagnosed with HCM were consecutively enrolled. 
Echocardiography and CMR with delayed hyper-enhancement imaging (DHE) was 
performed for each patient. Left ventricular (LV) regional and global 
longitudinal strain (SL(R) and SL(G)) were obtained by two-dimensional speckle 
tracking method on echocardiography. With CMR, regional myocardial wall 
thickness was measured, and the amount of DHE was calculated semi-quantitatively 
in each segment. Overall, 720 segments were analyzed. SL(R) was significantly 
decreased in the hypertrophied segments (thickness > 11 mm) and segments with 
DHE (P < 0.001). SL(R) was correlated with myocardial wall thickness (r = 0.47, 
P = 0.001) and amount of regional DHE (r = 0.39, P < 0.001). On multivariate 
analysis, regional LV wall thickness and amount of DHE were the only independent 
determinants of SL(R). SL(G) was associated with LV diastolic functional 
parameters in echocardiography, total DHE volume, and LV mass index. Total DHE 
volume and LV mass index were independent determinants of SL(G) on multivariate 
analysis. The extent of regional myocardial fibrosis is associated with regional 
myocardial function independently of morphological changes of the myocardium, 
and the correlation extended to global LV function. In this context, DHE may be 
a useful parameter to discover early myocardial dysfunction independently of LV 
hypertrophy.