Statistical methods
Before the formal trial commenced, we conducted a preliminary trial involving approximately 8 patients. These 8 patients were randomly assigned to the dapagliflozin treatment group and the placebo group. The preliminary trial lasted for 2 months, and upon its conclusion, an independent samples t-test was performed. The difference in LVEF between the dapagliflozin group and the placebo group was found to be approximately 5%. The standard deviations of LVEF data in both groups were approximately 5%. This preliminary trial provided the basis for selecting the treatment difference and standard deviation for our formal trial.A sample size of 30 patients per treatment group would provide a power of 90% to detect a treatment difference of 5% in LVEF assuming an SD of 5% at a significance level of 0.05 (two-sided), and a 6.2% dropout rate. Categorical variables in the baseline characteristics are presented as frequencies and percentages, while continuous variables are reported as means ± standard deviation (SD) or medians with interquartile ranges. Differences between groups were evaluated using the independent samples t-test or Mann-Whitney test for continuous variables, and the chi-square test or Fisher’s exact test for categorical variables. Comparison of two groups of echo responders using a chi-square test. Changes in various indices from baseline to 1 year were analyzed using analysis of covariance, with adjusted means (standard error) reported as the results. The analysis of covariance included the baseline value of each analyzed variable as a covariate. Safety analyses were performed on patients who were randomized and received at least one dose of either dapagliflozin or placebo. Statistical analysis was carried out using SPSS 22.0 software. A significance level of P < 0.05 was considered statistically significant.