Measurement variability

To assess reproducibility, the measurements of LA volume and strain by 4D Auto LAQ were repeated by the same observer on the same echocardiographic images in 10 randomly selected patients at least 1 weeks apart. These parameters were also analyzed by another independent observer blind to the patient grouping to ensure interobserver variability.

Statistical analysis

Statistical analysis was performed by SPSS 25.0 (IBM SPSS Statistics, Chicago, IL, USA). Normality was assessed with a normal probability (Q-Q) plot and with a Shapiro-Wilk test. Continuous variables were expressed as mean ± standard deviations, mean ± standard errors, median (inter-quartile range) or frequencies (percentages) as appropriate. Chi-square test or Fisher’s exact test were used to compare categorical variables. Independent t-test was performed for continuous variables. Non-normally distributed values were compared using the Mann–Whitney U test. The Pearson or Spearman correlation coefficients were used to evaluate the linear relationship between the variables. Univariate and multivariate logistic regression analyses were performed to determine factors associated with post-capillary PH. The factors with p ≤ 0.10 were selected as related variables for multivariate analysis. Receiver operating characteristic (ROC) curve analysis was used to compare the discriminative ability of the independent parameters and to determine the optional cutoff value. A two-sided p value of < 0.05 was considered statistically significant.