Objective This research is to explore the Junctophilin-2 ( JPH2 ) expression in persistent atrial fibrillation with mitral valve disease.Methods The left atrial tissue samples were taken from 34 patients with mitral valve disease who underwent cardiac surgery.16 patients were in sinus rhythm, 18 patients had persistent atrial fibrillation.Western blot tech-nique was used to test the JPH2 expression, and the RT-PCR method was used to test the JPH2 gene expression.Results The Westernblot results showed JPH2 expression down-regulated in persistent atrial fibrillation group (0.94 ±0.29 vs.1.53 ± 0.61,P<0.01).However, there was no difference with JPH2 mRNA expression between atrial fibrillation patients and sinus rhythm patients(1.76 ±1.38 vs.1.15 ±0.94, P>0.05).Expression of miRNA-24 was significantly up-regulated in patients with persistent atrial fibrillation(4.49 ±4.30 vs.1.72 ±1.08, P<0.05).There was no significant difference in mean age, gender, ejection fraction and NYHA among the two groups.But the left atrial diameter was significant larger in patients with persistent atrial fibrillation compared to those in sinus rhythm(P=0.02).Conclusion Junctophilin-2 protein down-regulation may be associated with atrial fibrillation , cause left atrial remodeling and contraction dysfunction .