Statistical analysis
Data were shown as means ± standard deviations for continuous variables and percentages for categorical variables. Pearson’s correlation coefficients were used to assess relationships between peak EL in ED, LD, and Sys (ED-EL, LD-EL, and Sys-EL, respectively) and age, height, weight, sex, comorbidities, heart rate (HR), BP, laboratory data, and echocardiographic parameters. A stepwise multivariate linear regression was performed to analyze independent variables that correlated with ED-EL, LD-EL, and Sys-EL. All statistical analyses were performed using SPSS software version 20 (IBM Inc., Chicago, IL, USA). A P value less than 0.05 was considered to be significant.