OBJECTIVETo observe the change of circulating microRNAs(miRNAs), regulatory mechanism in patients with atrial fibrillation (AF) before and after radiofrequency ablation (RFA).

METHODSFrom January 2011 to December 2013, peripheral blood samples were taken from 30 AF patients (10 paroxysmal, 10 persistent and 10 permanent AF) before and 3 months after RFA. The total RNA was extracted and hybridized with the miRNA chips, and the differential expression of miRNA and clustering analysis in whole genome were made with Volcano Plot and tMEV software respectively, and validated by real-time PCR. The target gene analysis of miRNAs was predicted through the Mirbase, Miranda and Targetscan databases. Results were compared with those from 10 healthy subjects (control group).

RESULTSCompared with control group, the expressions of 25 miRNAs were down-regulated before RFA and up-regulated after RFA in AF group, while other 40 miRNAs expression changed in the opposite way; among them, the expressions of 7 miRNAs including miR-199a-3p/miR-199b-3p were down- regulated >1.5-fold before RFA and up-regulated>100-fold after RFA; oppositely, 6 miRNAs including miR-BART8-3p were up-regulated>1.5-fold before RFA and down-regulated>10-fold after RFA. Interestingly, 6 miRNAs including miR-30b-5p, which were involved in AF-related electrical and structural remodeling, were down-regulated>5-fold before RFA, but up-regulated>50-fold after RFA. Four miRNAs including miR-377-5p, which were involved in the regulation of CACNA1C ICaL channel protein, were different before and after RFA.

CONCLUSIONmiRNAs regulate the occurrence and development of AF. RFA can change the expression of miRNAs in AF patients, which may be important for reversing the electrical and structural remodeling and maintaining sinus rhythm after RFA. miRNAs, such as miR-30b-5p, miR-377-5p and miR-199a-3p/miR-199b-3p etc., might become the target markers for early diagnosis and intervention of AF in future.