Age-dependent Dynamics of the Electrocardiographic Parameters in Cardiovascular Disease-Free Children.

BACKGROUND

Normative pediatric electrocardiographic (ECG) parameters are standardized, but lack temporal resolution for neonates and infants. These values are clinically important, as they support the diagnosis, risk stratification, and management of cardiovascular diseases (CVD).

METHODS

Five ECG parameters (heart rate (HR), QRS, PR, QT, QTc intervals) were retrospectively analyzed from 7,346 recordings from 6,967 patients at a large pediatric hospital. Patients were only included if their ECG was adjudicated as normal by a pediatric cardiologist. Patients were assigned to 45 age groups: neonates (1-35 days, 35 groups), infants (2-6 months, 5 groups), and young children (1-5 years, 5 groups). Sensitivity analysis ranked ECG parameters to determine those most affected by age. Z-scores were used to quantify deviations in developmental ECG parameter trajectories in CVD-free patients compared with unrepaired tetralogy of Fallot (TOF, n=305).

RESULTS

Developmental shifts in ECGs were observed for all patients, irrespective of whether intensive care unit or CVD patients were included in the analysis. All five ECG parameters differed significantly between early (1-8 days) and late neonates (9-35 days). Sensitivity analysis revealed rapid ECG parameter adaptations during the neonatal stage, with slower changes during infancy and early childhood. Unrepaired TOF patients had significantly different HR, PR, and QRS values in the late neonatal group compared with CVD-free children. Z-scores revealed disease-specific deviations (≥ 2 SD of baseline), including outlier QTc values in 32.7% and 24.3% of early and late neonatal TOF patients, respectively.

CONCLUSION

This study defined the values of five key ECG parameters, with enhanced age-specific resolution in neonates, infants, and children. Neonatal age emerged as the most dynamic stage for ECG parameter changes. This study demonstrated that high temporal resolution of age-specific ECG parameters can identify abnormal deviations, which can provide valuable insight for the diagnosis and management of CVD in early life.