Progressive Microstructural Remodeling in the Infarcted Left Ventricle Analyzed by Diffusion Tensor MRI

Myocardial infarction (MI) triggers a series of pathological events leading to progressive tissue remodeling that can impair the mechanical and electrical function of the heart. This study investigates the temporal progression of regional myocardial remodeling following MI. Using diffusion tensor magnetic resonance imaging (DT-MRI), we assessed changes in tissue microstructure across the infarct, border zone (BZ), and remote myocardium. Key DT-derived metrics - apparent diffusion coefficient (ADC), fractional anisotropy (FA), and tissue mode - were analyzed at 1-, 2-, 3-, and 4-week timepoints. Results indicate that while tissue mode in the BZ shows early changes consistent with fibrosis, alterations in FA and ADC occur later, reflecting more gradual remodeling. Notably, the BZ evolves into a distinct microstructural environment over time, transitioning from a state similar to the infarct to a unique microstructural state by the 3-week post-MI timepoint. Our findings suggest that DT-derived microstructural analysis may facilitate the optimal timing for therapeutic interventions, such as ventricular restraint devices, aimed at limiting infarct expansion and improving BZ contractility. This study provides a comprehensive framework for understanding the dynamic regional remodeling observed in the myocardial post-MI and highlights the potential of DT-MRI as a non-invasive tool for clinical assessment and therapeutic guidance. Ultimately, integrating such a framework with machine learning could streamline the clinical application of these diffusion metrics, enabling early detection of maladaptive remodeling and improving prognostic accuracy for heart failure and arrhythmia risk.