Abstract Body: Heart failure (HF) involves global genome modifications. Adverse structural and function remodeling that occurs in HF was initially considered to be irreversible. However, ~15% of HF patients on left ventricular assist device (LVAD) support show significant structural and functional reverse remodeling, distinguishing them as responders (R), while ~85% are non-responders (NR). DNA methylation and transcriptional changes that exert myocardial recovery is not well understood.

To address this, we performed whole-genome bisulphite sequencing and RNA sequencing on paired myocardial biopsies from HF patients (n=84) before (pre-LVAD) and after LVAD unloading (post-LVAD).

Post-LVAD samples showed activation of pathways including TGFβ signaling, PTEN and Fatty acid oxidation compared to pre. Integrating DNA methylation and transcriptomics data revealed hypomethylation (upregulation) of genes including Scaper, Frat1 and Magi1 and hypermethylation (downregulation) of Tpp3 and Icam. Overall, suggesting a unique ECM-specific stabilization pathway post-LVAD unloading.

Segregating samples based on their response to LVAD unloading, pathways such as inflammation and fibrotic signaling were activated in postNR compared to preNR. Hypomethylation of Magi1 and hypermethylation of Tppp3 was observed in postNR suggesting cross-linking proteins and destabilization of microtubule formation as potential mechanisms of functional regression in NR. Conversly, postR showed activation of deubiquitination, oxidative phosphorylation and NLR signaling compared to preR. Finally, we observed integrin signaling, syndecan interaction, collagen degradation and wound healing pathways were activated in postR compared to postNR. Hypomethylation of actin cytoskeleton (Myl12a), microtubule/motor proteins (Kif5b) and tropomyosin (Tpm3) were observed in postR, suggesting a plausible reverse remodeling mechanism mediated by ECM degradation and stabilization of myocardium in these patients. Western blot analysis also showed a trend towards an increase in collagen in postNR compared to postR (n=4, p=0.06). Finally, a mouse model of HF and recovery was used and pathways including ECM degradation and cardioprotective signaling were activated in mice that recovered from HF compared to mice that did not. Overall, our data suggests a unique ECM regulation pathway to contribute towards myocardial reverse remodeling in HF patients.