['The objective of this study was to compare the expression of heat shock proteins (HSPs) between rheumatic heart disease (RHD) patients with atrial fibrillation (AF) and RHD patients without AF, and its efficacy in predicting the occurrence of AF in RHD patients.', 'Ninety-five patients were enrolled in our study, including 60 RHD patients with AF, and 35 RHD patients without AF. The baseline characteristics of the patients such as gender, age, AF duration, left atrial diameter and left ventricular ejection fraction were collected, and erythrocyte sedimentation rate and high-sensitivity C-reaction protein were measured from all patients. Tissue samples were obtained from the right atrial appendage during open-heart surgery and then detected using immunohistochemical methods and Western blot with HSP27, HSP60, HSP70 and HSP90 antibodies.', 'Compared with RHD patients without AF, the density of HSP27 positive protein in RHD patients with AF was significantly lower. The density of HSP60, HSP70 or HSP90 antibodies did not indicate significant difference between the two groups. Use of the Western blot experiment showed consistent results with immunohistochemical staining. In RHD patients with AF, the expression level of HSP27 protein was negatively associated with AF duration and left atrial diameter. Left atrial enlargement and low expression of HSP27 were the independent predictors of AF.'] Is decreased Cardiac Expression of Heat Shock Protein 27 Associated with Atrial Fibrillation in Patients with Rheumatic Heart Disease?