Atrial fibrillation is not associated with altered left atrial microRNA expression profile in advanced heart failure patients.

Background: Atrial fibrillation (AF) is common in patients with chronic heart failure (HF). Nevertheless, some patients with HF remain in sinus rhythm (SR) even with marked left atrial (LA) dilatation and fibrosis. The underlying mechanisms for the differences in atrial arrhythmogenicity are poorly uncovered. Recent findings indicate that distinct microRNAs (miRNA) might induce LA structural and molecular alterations. However, the impact of miRNA dysregulation on AF development in the context of HF has not been studied independently of LA remodeling.

Objective: This study aimed to evaluate the differences in LA miRNA expressions in HF patients with AF or SR.

Methods: LA myocardial samples were obtained from advanced HF patients with AF (n=12; paroxysmal n=4, chronic as persistent/permanent n=8) or SR (n=12) undergoing heart transplantation. The extent of LA interstitial fibrosis was evaluated using picrosirius red-staining. The LA load was estimated by measuring LA mRNA expression of the NPPA gene encoding atrial natriuretic peptide with qRT-PCR and circulating N-terminal proatrial natriuretic peptide (NT-proANP) by ELISA. The LA miRNA screening was performed using the NanoString technology.

Results: LA dilatation, fibrosis, NPPA gene expression, as well as circulating NT-proANP levels were similar between the AF and SR groups, suggesting a comparable extent of atrial remodeling and load among the study groups. The miRNA analysis revealed no differences in atrial miRNA expression between the groups, even after AF subgroup analysis.

Conclusion: The LA miRNA expression profile shows no distinction between AF and SR in advanced HF patients with similar levels of pathological atrial remodeling.