Abstract 4369220: In Vivo Cardiac Diffusion Tensor Imaging for the Differentiation between Hypertrophic Cardiomyopathy and Hypertensive Heart Disease: Insights into Myocardial Microstructure

Background: Left ventricular hypertrophy (LVH) is a common feature of both hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD), making differentiation through macrostructural imaging challenging. Given the distinct tissue characteristics of these two conditions, the emerging cardiac diffusion tensor imaging (cDTI) allows in vivo characterization of myocardial microstructure, offering insights for differential diagnosis. Purpose To validate the feasibility of cDTI for non-invasive myocardial microstructural characterization in HCM and HHD and to explore its potential value in distinguishing them. Materials and methods: In this prospective study, 40 participants diagnosed with HCM, 20 diagnosed with HHD and 20 controls were enrolled. All consecutively underwent a 3.0-T CMR protocol including DTI, cine imaging, T1 mapping and late gadolinium enhancement (LGE) imaging. LGE was performed in HCM and HHD participants. Fractional anisotropy (FA) and secondary eigenvector angle (E2A) were assessed after adjusting for hypertrophy and fibrosis. Results: FA was reduced in HCM and HHD participants compared with healthy controls (FA HCM = 0.32 ± 0.05, FA HHD = 0.4 ± 0.07, FA Control = 0.46 ± 0.06, p<0.001). Meanwhile, HCM participants had significantly higher E2A (E2A HCM = 49.2 ± 7.1°, E2A HHD = 38.7 ± 5.3°, E2A Control = 38.1 ± 5.3°, p<0.001). FA (p=0.005) and E2A (p=0.002) remained significant even after adjusting for left ventricular wall thickness (LVWT), native T1 and extracellular volume (ECV). FA showed the best diagnostic performance in identifying HCM (area under the curve [AUC]=0.97), HHD (AUC=0.75) from healthy controls and differentiating HCM from HHD (AUC=0.84). E2A also exhibited excellent precision for identifying HCM (AUC=0.89) and discriminating HCM from HHD (AUC=0.87). Conclusions: In our study, there were significant differences in FA and E2A between HCM and HHD even after adjusting for hypertrophy and fibrosis. cDTI demonstrates potential as a useful tool for discriminating HCM, HHD and healthy controls with great diagnostic efficiency.