Statistical analysis
We estimated that 32 patients would be needed to find a 10-ms difference in the QRS duration between MPP and MPP-FOI with an α = 0.05 and a statistical power (1-β) of 80%, assuming a standard deviation of 20 ms for pair differences.
Categorical variables, represented as proportions, were compared using the χ² test. Continuous variables, after confirming their normal distribution (QQ plot), were expressed as the means and standard deviations, and between-group comparisons were made using Student’st -test. Linear mixed-effects models with a repeated-measures structure were used to assess differences in the QRS duration, echocardiographic measures, and biventricular activation times (using ECGI) across the three pacing modes. The correlation between the duration of the QRS complex (ECG) and activation time (ECGI) was assessed using the Pearson coefficient. A two-tailed P< 0.05 was deemed statistically significant. All statistical analyses were conducted using SPSS software v22.0 (SPSS Inc., USA) or R v3.6.1 (R Project for Statistical Computing; Vienna, Austria).