Statistical Analysis
As to continuous data, they are expressed as mean values ± standard deviation (SD) if they meet normal distribution. If not, their median and inter-quartile ranges are described. All data were compared by Student’s t-test or Wilcoxon rank sum test whenever appropriate. On the other hand, categorical data were presented as percentages and compared by chi-square or Fisher exact test. Univariate and multivariate regression analyses were used to identify clinical variables that were associated with aortic cusp bending. JMP ver12.0 (SAS Institute, Cary, USA) was used for statistical analyses. A p value of < 0.05 was considered statistically significant.