Statistical analysis
Continuous variables are presented as mean ± standard deviation or median ± interquartile range (IQR, 25–75th percentile), depending on the normality of distribution. Categorical variables are reported using numbers and percentages. Event-free survival curves were constructed using the Kaplan–Meier method and compared using the log-rank test. We compared the prevalence of VT recurrence at 2 years between two groups using the Wilcoxon rank-sum test. Event-free survival curves among four groups in the total population were also constructed using the Kaplan–Meier method and compared using the log-rank test. Bonferroni test for post-hoc analysis for the intergroup comparison of each pair of groups. This post-hoc test sets the significance cut off at 0.05/4 (= 0.0125). All reported P-values are two-sided, with a P-value of <0.05 considered to indicate statistical significance. Statistical analyses were performed using the Statistical Package for Social Studies version 25.0 (IBM Corp., Armonk, NY, USA).