Characteristics and circadian distribution of cardiac arrhythmias in patients with heart failure and sleep-disordered breathing

Cardiac arrhythmias and sleep-disordered breathing (SDB) are common comorbidities in heart failure with reduced ejection fraction (HFrEF). However, understanding of the association between arrhythmias and SDB is poor. This study assessed the occurrence and circadian distribution of ventricular arrhythmias in HFrEF patients with and without SDB. This retrospective analysis included HFrEF patients admitted for unattended overnight cardiorespiratory polygraphy and 24-h Holter-ECG recording. Holter-ECG data (events/h) were categorized by time of day: morning, 06:00–13:59; afternoon, 14:00–21:59; nighttime, 22:00–05:59. Respiratory events were expressed using the apnea–hypopnea index (AHI) and an AHI ≥ 15/h was categorized as moderate to severe SDB. 167 patients were included (82% male, age 65 ± 10.4 years, left ventricular ejection fraction 30.9 ± 7.9%); SDB was predominantly central sleep apnea (CSA) in 45.5%, obstructive sleep apnea (OSA) in 23.9% or none/mild (nmSDB) in 17.4%. Morning premature ventricular contractions (PVCs) were detected significantly more frequently in CSA versus nmSDB patients (44.4/h versus 1.8/h; p = 0.02). Non-sustained VT was more frequent in patients with CSA versus versus OSA or nmSDB (17.9 versus 3.2 or 3.2%/h; p = 0.003 and p = 0.005, respectively). There was no significant variation in VT occurrence by time of day in HFrEF patients with CSA (p = 0.3). CSA was an independent predictor of VT occurrence in HFrEF in multivariate logistic regression analysis (odds ratio 4.1, 95% confidence interval 1.5–11.4, p = 0.007). CSA was associated with VT occurrence irrespective of sleep/wake status in HFrEF patients, and independently predicted the occurrence of VT. This association may contribute to chances by which CSA increases sudden death risk in HFrEF patients.