Objective:To investigate the expression of serum galectin-3 in elderly patients with or without atrial fibrillation and to explore its impact on the prognosis of patients with atrial fibrillation.Methods:In this retrospective study, 100 patients aged 60 years or older treated at the Department of Geriatric Cardiovascular Medicine, Second Xiangyang Hospital, Central South University between March 2018 and September 2018 were enrolled.Based on electrocardiogram and previous history of atrial fibrillation, 73 participants were assigned to the atrial fibrillation group and 27 patients with sinus rhythm and no history of atrial fibrillation during the same period served as the control group.Elisa kits were used to measure the expression of galectin-3 in both groups, and echocardiography was used to measure the size of each cardiac chamber in patients.The Mann-Whitney test was used to compare galectin-3 levels between the two groups, and binary logistic regression analysis was used to determine risk factors for atrial fibrillation in the elderly.Kaplan-Meier survival curves and Cox proportional risk regression were used to analyze survival and the relationship between galectin-3 and prognosis.Results:Serum galectin-3 levels of patients in the atrial fibrillation group were higher than in the control group[(395.13±113.24)ng/L vs.(328.53±89.11)ng/L, t=2.626, P<0.01]. The level of galectin 3 in participants aged ≥ 65 years(n=48)was higher than in those aged<65 years(n=52), (414.01±105.03)ng/L vs.(343.11±106.01)ng/L( t=2.626, P<0.01). The galectin-3 level had a positive correlation with age( r=0.40, P<0.01), duration of atrial fibrillation( r=0.224, P<0.05)and C-reactive protein( r=0.305, P<0.01), but no correlation with N-terminal pro-B-type natriuretic peptide, atrial or ventricular size and the score of CHA2DS2-VASc in patients with atrial fibrillation, .Galectin-3 was a risk factor in patients with atrial fibrillation( P<0.01). Galectin-3 levels did not affect survival(log-rank=0.990)or prognosis( P>0.05)in patients with atrial fibrillation. Conclusions:Galectin-3 levels in elderly atrial fibrillation patients are higher than in people without atrial fibrillation and are positively correlated with age, duration of atrial fibrillation, and C-reactive protein.Galectin-3 is a risk factor for atrial fibrillation in elderly patients.