Community-acquired pneumonia alters circadian regulation of cardiac electrophysiology in children

The effects of community-acquired pneumonia (CAP) on cardiac electrophysiology have been described in children; however, their relationship with physiological circadian regulation remains unclear. This study aimed to evaluate morning-evening variations in electrocardiographic parameters in children with CAP compared to healthy controls. Thirty-six children diagnosed with CAP and 47 healthy controls were included. Electrocardiographic recordings were obtained in the morning and evening. Heart rate, atrial conduction parameters, and ventricular repolarization indices were analyzed to assess time effects, group differences, and time × group interactions. Children with CAP exhibited higher heart rates and shorter atrial conduction parameters than controls at both time points. Ventricular repolarization indices were increased in the pneumonia group. Tp-e/QT and Tp-e/QTc ratios were higher in children with CAP but did not show significant temporal variation. The frontal QRS-T angle demonstrated limited diurnal variation in healthy controls, whereas no significant temporal change was observed in the pneumonia group. Associations between Tp-e/QT, Tp-e/QTc, and QTc differed according to measurement time.Conclusion: Children with CAP demonstrate alterations in atrial conduction and ventricular repolarization compared with healthy peers. These findings suggest that CAP may be associated with temporal changes in specific electrophysiological relationships rather than a complete loss of physiological circadian regulation.