Statistical analysis
The data are presented as frequencies and percentages for qualitative variables and means ± standard deviations for quantitative variables. To compare the two groups, Mann-Whitney U tests were used for continuous variables, and χ2 tests or Fisher exact tests were used for categorical variables. Kaplan-Meier analysis was performed to assess the time required for recurrence of AF. The AF-free survival was compared by log-rank test. Statistical analyses were performed using SPSS 23.0 software (Chicago, IL, USA). For all analyses, a P-value of <0.05 was considered statistically significant.