Participants
All children (0 – 18 years of age) who had echocardiogram and PSG performed within 6 months of one another were included in the study. Echocardiograms were reviewed by JW and EE and the cohort was divided into groups with (+HF) and without heart failure (-HF). The +HF group was defined by left ventricular ejection fraction (LVEF) of ≤45% or moderate to severe cardiac dysfunction. The -HF group was defined by LVEF of ≥58% or normal cardiac function and therefore was deemed appropriate for the control group15. Values in the intermediate range were excluded to ensure that the population being studied had significant enough cardiac dysfunction to confidently separate them from the controls. Exclusion criteria included structural congenital heart disease with right to left shunting, neurological conditions associated with CSA such as Arnold Chiari malformation, congenital central hypoventilation syndrome, patients on non-invasive ventilation or tracheostomy at the time of PSG, and patients with inadequate sleep time defined by total sleep time less than 120 minutes.
All patient charts with test data in the study time period were reviewed with 50,144 children identified and screened for eligibility. Figure 1 shows the screening process for the study. The initial cohort was screened for individuals with both PSG and echocardiogram within 6 months of each other before being divided into +HF and -HF groups based on echocardiogram results. To limit the control cohort to a reasonable size, we only included data on children with -HF from January 1, 2019 through December 31, 2019. Exclusion criteria were then applied with 120 patients ultimately confirmed to be eligible and included in the study.