Statistical analysis
All continuous variables were expressed as means ± standard deviations and compared using independent-sample Student t-tests or Mann-WhitneyU test. Categorical variables were expressed as frequencies and percentages and compared using Pearson’s chi-square test or Fisher’s exact tests. Univariate and multivariate logistic regression models with backward elimination processes were performed to identify independent risk factors associated with the occurrence of ERAT after surgical AF ablation. The p - value for variables to enter and stay in the prediction models was set at 0.05.
Time to first LR was computed and plotted using the Kaplan-Meier method and compared using log-rank test. Cox proportional hazards regression analyses were used to estimate hazard ratio (HRs) with 95% confidence intervals (CIs). Variables reported in Tables 1 and 2 with a p - value of ≤ 0.05 in the univariate analyses were candidates for the multivariable Cox proportional hazards models. The final models were determined using backward elimination processes. To redefine an ideal cut-off value for the blanking periods, a receiver operating characteristic (ROC) analysis was performed, the area under the curve (AUC) was calculated, and the possible cut-off points were selected. All statistical analyses were performed using R software version 3.5.3 (https://cran.r-project.org/).