2.6 Statistical analysis
Continuous variables are expressed as mean ± SD values or median, and categorical variables are expressed as the number and percentage of patients. Student’st -test or Mann-Whitney U test was used, as appropriate, to analyze between-group differences in continuous variables, and the chi-square test was used to analyze between-group differences in dichotomous variables unless the expected counts were < 5, in which case Fisher’s exact test was used. Receiver operating characteristic (ROC) curves were plotted to determine the cutoff values of the ablation-related variables for prediction of gaps. The areas under the curve (AUC) were compared by DeLong test. The ROC curves and AUCs were analyzed with MedCalc ver. 16.4.1 (MedCalc Software, Mariakerke, Belgium). All other statistical analyses were performed with JMP 11 software (SAS Institute, Cary, NC). P < 0.05 was considered statistically significant.