Statistical analysis:
Patient characteristics were expressed as the mean ± standard deviation or as percentages. Continuous variables in two groups were compared by student t test or Man Whitney U test. Distribution of categorical variables were analyzed by using χ2 or Fisher’s exact test when appropriate. Pearson’s correlation was used to test the relationship between the continuous variables. Significant parameters in the univariate analysis (p= < 0.05) were included in the multivariate analysis. Multivariate Cox regression analysis (enter models) was used to determine independent predictors of AF. Receiver operating characteristic (ROC) curves were plotted and area under the curve (AUC) was calculated for the prediction of occurrence of atrial fibrillation. All statistical analyses were performed with SPSS version 24.0 (SPSS, Inc, Chicago, IL), and P values of <0.05 were considered as statistically significant.