Investigation into relationship between etiology of dilated cardiomyopathy and type, patterns and course of fibrosis reveals fibrosis progression in genetic patients.

Background: Dilated cardiomyopathy (DCM) is a highly heterogenous condition, resulting from both genetic and non-genetic mechanisms. However, little is known about the amount, pattern and time course profile of fibrosis in DCM patients and different etiology.

Aims: To evaluate the type, pattern and course of fibrosis assessed with late gadolinium enhancement (LGE) and extracellular volume (ECV) on cardiovascular magnetic resonance (CMR) in patients with DCM of different etiologies.

Material And Methods: We prospectively enrolled 102 DCM (87.3% male, mean age 45.2 [11.8] years). Patients were divided into 5 etiological sub-groups: toxic, inflammatory, tachyarrhythmic, genetic and idiopathic. All patients underwent two CMR scans at baseline and after 12 months, assessing replacement fibrosis via LGE and interstitial fibrosis via ECV.

Results: The distribution of etiologies was: toxic (26.5%), idiopathic (26.5%), genetic (23.5%), inflammatory (13.7%), and tachyarrhythmic (9.8%). At baseline, LGE was present in 45 (44.1%) patients and in 46 out of 92 (50%) patients at 12 months. 10 patients did not complete follow-up CMR (3 died, 1 underwent heart transplantation, and 6 received implantable cardiac devices). The predominant LGE pattern was linear mid-wall (57.8%), followed by transmural (17.8%), sub-endocardial (8.9%), patchy mid-wall (6.7%), right ventricular insertion points (4.4%), and mixed patterns (4.4%). No differences in LGE presence, pattern, and localization were observed among the etiology-based DCM sub-groups. Similarly, ECV values did not differ significantly between groups. The analysis between baseline and the 12- month parameters revealed that only in genetic DCM did LGE mass and extent significantly increase (6.8 [2.1-10.9] vs. 7.4 [2.5-16.9] g; and 3.0 [0.9-5.9] vs. 3.3 [1.4-9.4]%; both P <0.05).

Conclusions: In DCM, LGE presence, pattern, and localization did not differ across etiological subgroups. However, myocardial fibrosis progression, reflected by increased LGE mass and extent, occurred exclusively in patients with genetic DCM.