Statistical Analysis
Continuous variables were reported as mean ± standard deviation, whereas categorical variables were expressed as percentage values. Normal distribution of the data was tested using the Kolmogorov-Smirnov test and categorical variables were compared using the chi-square test. Comparisons of normally distributed continuous variables were performed with the Student’s t-test and the Mann Whitney-U test was used for non-parametric continuous variables. Analysis of variance (ANOVA) followed by the Tukey correction was used to assess difference among 3 groups. The correlation between variables was examined by Pearson’s correlation coefficient. Multiple logistic regression analyses were performed to define risk factors of outcome variable. All potentially relevant confounding factors were considered all together in the model. Intraobserver variability of echocardiographic RV functional measurements was assessed using intraclass correlation coefficients and coefficients of variation. P value <0.05 was considered statistically significant. Statistical analyses were performed using the Statistical Package for the Social Sciences statistical software (version 25; SPSS-IBM, Chicago, IL, USA).