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 morphological improvement was observed during 18 months observation in DCM patients on GDMT. The greatest improvement occurred during the first 3 (occasionally 6) months which was associated with the greatest escalation of GDMT. Further dose escalation was not associated with a significant improvement in both functional and morphological parameters.