Relationships between 18-month kinetics and functional capacity and left ventricular remodeling and cardiac fibrosis in dilated cardiomyopathy

Abstract Introduction Myocardial fibrosis is a primary pathogenetic process in dilated cardiomyopathy (DCM) that is responsible for progressive cardiac remodeling and functional capacity impairment. We sought to verify whether there were differences between 18-month kinetics of functional capacity and left ventricular remodeling in DCM patients with different types and advancement of fibrosis who were up-titrated with guideline directed pharmacotherapy (GDMT). Methods Between May 2019 and September 2020, 99 DCM patients (88 male, mean age 45.2 ± 11.8 years, mean EF 29.7 ± 10%) underwent cardiac magnetic resonance with assessment of replacement fibrosis via late gadolinium enhancement (LGE) and interstitial fibrosis via extracellular volume (ECV). Each patient had serial (baseline, 6-, 12-, 18 month) functional assessment: NYHA class and 6- minute walking test (6-MWT) and follow-up echocardiography, including measurement of left ventricular end-diastolic volume (LVEDvol) and ejection fraction (EF). Patients were divided into LGE-negative and LGE-positive groups, whereas based on median ECV – they were divided into those with ECV below and above median values. Results Overall, LGE was identified in 44 (44%) of patients, whereas median ECV was 27.7%. NYHA class was significantly worse in patients with LGE (1.5±0.5 vs. 1.9±0.6) and with higher ECV (1.93±0.6 vs. 1.6±0.5) in comparison to those without LGE and lower ECV. However, NYHA class improved during observational period in all groups. There were no differences in 6-MWT distance in LGE positive and negative groups at all time points. Baseline 6-MWT distance in LGE positive group was 494.2±88.2 vs. 453.9±98.8 meters in LGE negative group. Baseline 6-MWT distance in upper median ECV group was (408.8±103.5 vs. 492.4±92.9 meter) was significantly lower ECV group (p=0.03). During 18 months 6-MWT distance increased only in LGE negative group but in both ECV groups (Figure 1 A-D). There were no differences in EF between patients with and without LGE and also with higher and lower ECV. Baseline EF in LGE positive group was 27.4±11.2% and 31.7±10.6% in LGE negative. Baseline indexed LVEDvol in LGE positive group was 107.7±40.7 vs. 91.8±37.8 ml/m2 (p=0.09) in LGE negative group. EF increased significantly in both groups, whereas indexed LVEDvol decreased only in LGE negative group (Figure 2 A-D). Conclusions Regardless of the presence of replacement and to some extent of interstitial fibrosis, functional and cardiac