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.