MRI native T1 and T2 mapping of myocardial segments in hypertrophic cardiomyopathy: tissue remodeling manifested prior to structure changes.

Objective: The aim of this study was to examine the local myocardial segments in hypertrophic cardiomyopathy (HCM) by MRI T1 and T2 mapping, and to investigate how tissue remodeling correlates with structural and functional remodeling in HCM.

Methods: 47 patients with HCM and 19 healthy volunteers were enrolled in this study. All subjects underwent cardiac MRI at 3.0 T. Native T1 and T2 values, end-diastolic wall thickness (EDTH), and percentage of systolic wall thickening (PSWT) were assessed in the left ventricular segments according to the American Heart Association model. Myocardial segments were categorized as normal, non-hypertrophic, mild-hypertrophic, moderate-hypertrophic, and severe-hypertrophic based on EDTH. The difference among all five groups, and the correlation between native T1 and T2 values, EDTH, and PSWT were evaluated.

Results: Native T1 and T2 values were significantly elevated in both non-hypertrophic and hypertrophic segments of HCM patients compared to controls (both < 0.001). PSWT was preserved in non-hypertrophic segments ( = 0.838), while significantly impaired ( < 0.001) in hypertrophic segments. Native T1 value of severe hypertrophic segments in HCM was significantly higher than segments of mild and moderate hypertrophy ( < 0.05).

Conclusion: In HCM patients, the non-hypertrophic myocardial segments already demonstrated significantly elevated T1 and T2 values, despite normal wall thickness and preserved contraction function. The finding suggests that tissue remodeling may precede morphological and functional remodeling in HCM. MRI native T1 and T2 mapping can provide additional value for HCM diagnosis at an early stage.

Advances In Knowledge: Myocardial tissue remodeling, as detected by MRI native T1 and T2 mapping, occurs earlier than morphological and functional changes in HCM patients.