2.5 Statistical analysis
Continuous variables were expressed as median (interquartile range), and categorical variables were presented as numbers and percentages. Student paired t test or Wilcoxon signed rank test were used to compare pre- and post- procedure variables within patients, as appropriate. Comparisons between patients with or without significant increase in LVOT gradient were performed using the student’s t test, Wilcoxon rank sum test, or chi-square test, as appropriate. LVOT areas and dimensions among 3 levels: valve stent distal edge, middle portion, and aortic annulus, were compared using one-way analysis of variance with post hocTukey-Kramer testing. The linear regression between continuous variables was made using Pearson’s correlation coefficient. For linear correlation, ΔPG was log-transformed after adding a constant number (2.0) to the variables to make them positive and non-zero. To identify the independent association with LVOT area at the valve stent distal edge, multivariate linear regression was used among variables including those LV end-systolic volume (LVESV), LV ejection fraction (LVEF), and AM angle which were significantly associated with LVOT area at the valve stent distal edge in univariate analysis. A P value of <0.05 was considered significant. All statistical analyses were performed with JMP 10.0 (SAS Institute Inc., Cary, North Carolina).