Long-term changes in heart rate variability in elementary school-aged children with sleep-disordered breathing

Sleep-disordered breathing (SDB) in adults and children has been associated with reduced heart rate variability (HRV) indicative of autonomic dysfunction, which in turn is associated with an increased risk for cardiovascular morbidity. However, the long-term effects of pediatric SDB that has either resolved or remains unresolved on HRV are unknown.

Forty Children with previously diagnosed SDB and 20 non snoring controls underwent repeat overnight polysomnography (PSG) four years after the original diagnosis. At follow-up, children aged 11 to 16 years were categorized into resolved (absence of snoring and obstructive apnea hypopnea index [OAHI]≤1) or unresolved (continued to snore or had an OAHI>1) groups. HRV was assessed using power spectral analysis for each sleep stage.

There were no group differences in age, sex or body mass index (BMI) z score. Both the resolved and unresolved SDB groups showed significant improvement in OAHI. The control, resolved, and unresolved groups all showed a significant reduction in total power (P<.001), low-frequency (LF) power (P<.05), high-frequency (HF) power (P<.001), and an increase in the LF/HF ratio (P<.001) from baseline to follow-up in all sleep stages.

HRV did not differ between non snoring children and children with resolved and unresolved SDB four years after initial diagnosis, concomitant with a significant reduction in OAHI in both SDB groups. All groups demonstrated a decrease in HRV from baseline to follow-up which may reflect an age-related phenomenon in these children.