Identification of atrial fibrillation-associated microRNAs in left and right atria of rheumatic mitral valve disease patients.

MicroRNA (miRNA) is associated with the development and pathology of atrial fibrillation (AF). In this study, we performed miRNA profiling of left and right atrium samples from individuals with AF-associated rheumatic mitral valve disease (RMVD) to identify miRNAs that are differentially expressed between RMVD patients with AF and RMVD with sinus rhythm (SR) as controls, as well as between left and right atrium samples from RMVD with AF patients. We performed hematoxylin and eosin staining as well as scanning and transmission electron microscopy to examine in detail any morphological and physiological changes in cardiomyocytes from RMVD patients with AF or SR. Raman spectroscopy was performed to identify molecular and structural information of left and right atrium samples from RMVD with AF and SR. We also performed miRNA array profiling to separately profile miRNA expression patterns of right and left atrium samples from three independent RMVD patients with AF and in a mixed pool of 10 RMVD patients with SR. Morphological and physiological analysis showed distinct shapes and structures of cardiomyocytes from the left and right atria of RMVD patients with AF or SR. The intensity of Raman spectroscopy of atrial tissues from RMVD patients with AF and with SR was different. miRNA profiling showed differential miRNA expression between RMVD patients with AF or SR, and between the left and right atria of RMVD patients with AF. Importantly, miRNAs showed consistent expression changes among all three patients, suggesting that these miRNAs have potential as markers for AF pathology. Our results revealed potential biomarker miRNAs for atrial fibrillation pathology in patients with RMVD. Meanwhile, our data suggested that miR-10b and miR-138-2, which were both significantly increased in the left atrium, are responsible for morphological and physiological phenotype differences between the left and right atria.