ObjectiveTo investigate different expressions of microRNA-1 (microR-1) microRNA-133(microR-133) microRNA-34a (microR-34a) and their possible target protein Ankyrin-B in right atrial appendage of patients with atrial fibrillation (AF) or sinus rhythm (SR) analyze their correlation,and explore novel mechanisms of the pathogenesis and development of AF in microRNA level. MethodsForty right atrial appendage samples of 40 patients with rheumatic heart disease who underwent heart valve replacement in Xinqiao Hospital,Third Military Medical University were included in this study. All the patients were divided into AF group including 8 males and 12 females with their age of 52.9±5.8 years and SR group including 9 males and 11 females with their age of 52.4±6.2 years. The expression of microR-1,microR-133 and microR-34a were examined with RTQ-PCR (real-time quantitative PCR) and calculated with delta delta Ct method. Different expressions of ankyrin-B between AF and SR group were examined with immunohistochemistry and Western Blotting. ResultsMicroR-1 expression of right atrial appendage of AF group was significantly lower than that of SR group (0.559±0.252 vs. 3.997±1.251,t=-21.455,P=0.000) microR-133 expression of AF group was significantly lower than that of SR group (0.630±0.238 vs. 5.514±1.549,t=24.133,P=0.000) and microR-34a expression of AF group was significantly higher than that of SR group (4.783±2.012 vs. 1.350±0.638,t=12.596,P=0.000). Immunohistochemistry and Western Blotting showed Ankyrin-B expression in right atrial appendage of AF group was significantly lower than that of SR group (0.66±0.45 vs. 1.09±0.42,t=-3.396,P=0.001). ConclusionMicroR-34a may take part in the pathogenesis and development of AF by regulating the expression of Ankyrin-B.