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

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 left atrial (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 patients with HF with AF or SR. METHODS: LA myocardial samples were obtained from patients with advanced HF 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 quantitative real-time polymerase chain reaction and circulating N-terminal pro-atrial natriuretic peptide (NT-proANP) by enzyme-linked immunosorbent assay. 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. CONCLUSIONS: The LA miRNA expression profile shows no distinction between AF and SR in patients with advanced HF with similar levels of pathological atrial remodeling.