Statistical analysis
Categorical variables were expressed as the mean ± standard deviation (SD) or median with interquartile range (IQR). Student’s t-test was used to compare characteristics of the segments with acute PVR and those without. Receiver-operating characteristics (ROC) curve analysis was utilized to identify the most optimal cut-off value (with a Youden index) to predict acute PVR among various indices, and to determine the cut-off value with the specificity of 90%. Logistic regression analysis was performed to evaluate predictors of acute PVR in univariate and multivariate model for all segments, and region-specific analysis. The log-rank test was carried out for Kaplan-Meier curve analysis to assess cumulative rate of ATA-free survival in all subjects. All tests were considered statistically significant at P -value <0.05. All statistical analyses were performed with JMP® 13 (SAS Institute Inc., Cary, NC, USA).