Temporal progression of replacement and interstitial fibrosis in optimally managed dilated cardiomyopathy patients: A prospective study

Background: To prospectively examine the dynamic evolution of fibrotic processes within a one-year in patients with dilated cardiomyopathy (DCM). Methods: Between May 2019 and September 2020, 102 DCM patients (mean age 45.2 ± 11.8 years, EF 29.9 ± 11.6%) underwent cardiac magnetic resonance (CMR-1). After 13.9 ± 2.9 months, 92 of these patients underwent a follow-up CMR (CMR-2). Replacement fibrosis was assessed via late gadolinium enhancement (LGE), quantified in terms of LGE mass and extent. Interstitial fibrosis was evaluated via T1-mapping and expressed as extracellular volume fraction (ECV). This data, along with left ventricular (LV) mass, facilitated the calculation of LV matrix and cellular volumes. Results: At CMR-1, LGE was present in 45 patients (48.9%), whereas at CMR-2 LGE was detected in 46 (50%) (p = 0.88). Although LGE mass remained stable, LGE extent increased from 2.18 ± 4.1% to 2.7 ± 4.6% (p < 0.01). Conversely, ECV remained unchanged [27.7% (25.5–31.3) vs. 26.7% (24.5–29.9); p = 0.19]; however, LV matrix and cell volumes exhibited a noteworthy regression. During a subsequent follow-up of 19.2 ± 9 months (spanning from CMR-2 to April 30th, 2023), the composite primary outcome (all-cause mortality, HTX, LVAD or heart failure worsening) was evident in 18 patients. Only the LV matrix volume index at follow-up was an independent predictor of outcome (OR 1.094; 95%CI 1.004–1.192; p < 0.05). Conclusions: In optimally managed DCM patients, both replacement and interstitial fibrosis remained stable over the course of one year. In contrast, LV matrix and cell volumes displayed significant regression. LV matrix volume index at 12-month follow-up was found to be an independent predictor of outcome in DCM.