Table 1.

Population Characteristics

Parameter
N	646
Age (years)	8.54 ± 1.86
Gender (male)	348 (53.9%)
Age distribution (N)
6–7 years	150 (23.2%)
8–9 years	213 (33.0%)
≥10 years	283 (43.8%)
Heart rate (beats per minute)	95.3 ± 15.8
QRS duration (ms)	83.4 ± 9.3

Continuous variables are expressed as mean ± standard deviation. Categorical ones are summarized as counts (%).