2.7 Statistical analysis
Continuous variables are expressed as mean ± SD values or median and interquartile range, and categorical variables are expressed as the number and percentage of patients. Student’s t -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 values in cells were <5, in which case Fisher’s exact test was used. Strength of the relation between continuous variables (size of LVZs at LA-ascending aorta contact areas), BW, BMI, aorta-LA angle, aorta-LV angle, and NCC diameter) was assessed on the basis of Pearson’s correlation coefficient. All statistical analyses were performed with JMP 11 software (SAS Institute, Cary, NC), and P <.05 was considered statistically significant.