Microstructural disease and hypoperfusion in dilated cardiomyopathy underpin midwall septal fibrosis.

backgroundThe presence of midwall septal fibrosis (MSF) in dilated cardiomyopathy (DCM) has been shown to be associated with adverse clinical outcomes, but the underlying pathophysiological mechanisms are incompletely understood. We investigated whether MSF associates with a distinct pattern of myocardial microstructural and microvascular abnormalities using advanced cardiovascular magnetic resonance (CMR).

methodsThis was a prospective, multi-referral, single-center study comparing the hearts of patients with a current or prior diagnosis of DCM with and without MSF ("MSF+"/"MSF-"), to a control cohort of a similar age and sex distribution. All underwent single-magnet 3 Tesla CMR, including cardiac diffusion tensor imaging (cDTI), quantitative rest perfusion, and multiparametric tissue characterization. Prespecified analyses compared DCM with controls, and MSF+ with MSF-; secondary analyses included regional septal and within-subject segmental comparisons.

resultsAbout 121 participants were studied: 34 MSF+ (51±14years; 74% male), 27 MSF- (48±15 years; 63% male), and 60 controls (45±13 years; 58% male). Compared with controls, the DCM cohort demonstrated increased mean diffusivity (MD) (1.49 v 1.43 ×10

conclusionMidwall septal fibrosis in DCM identifies a distinct myocardial phenotype characterized by microstructural remodeling and impaired myocardial perfusion, with regional and segmental specificity. These findings provide mechanistic insight into the adverse prognostic associations of MSF and highlight a potential imaging-guided pathway for risk stratification and therapies.