3 Statistical analysis
Continuous variables are expressed as mean ± standard deviation and compared with the unpaired t-test. Dependent continuous variables were compared with paired t-test. Categorical variables are expressed as percentile value and compared with the Chi-square or Fisher’s exact test as appropriate. Multivariate logistic regression analysis was performed to adjust the influence of covariates. A general linear model (analysis of covariance) was applied to evaluate the impact of RFCA on LAA flow volume while controlling the effect of covariates. Estimated means calculated by general linear model are presented as mean values with 95% confidence intervals. Results were considered to be significant if the p-value was <0.05 on a two-tailed test. All statistical analyses were performed using IBM SPSS Statistics software, Version 24.0 (IBM, Armonk, NY).