Cyclic Variation in Heart Rate Score by Holter Electrocardiogram as Screening for Sleep-Disordered Breathing in Subjects With Heart Failure

BACKGROUND: Sleep-disordered breathing (SDB) is critically associated with cardiovascular mortality and morbidity, especially in patients with heart failure (HF). However, the majority of SDB patients remain undiagnosed. In contrast, abnormality in heart rate variability has been reported in patients with SDB. To explore an efficient electrocardiogram (ECG)-based screening tool for SDB, we examined the usefulness of cyclic variation in heart rate score (CVHRS) by Holter ECG in subjects with HF. METHODS: In this study, 102 subjects with HF were enrolled. We simultaneously performed Holter ECG with overnight portable sleep monitoring, and we measured the respiratory disturbance index (RDI) and CVHRS. We determined the temporal position of the individual dips comprising the CVHRS using time-domain methods. CVHRS was measured as cyclic and autocorrelated dips in smoothed interbeat interval time series. RESULTS: There were 25 subjects with severe SDB (RDI ≥ 30 events/h) and 77 subjects with none-to-moderate SDB (0 ≤ RDI < 30 events/h). There was a significant positive correlation between CVHRS and RDI (r = 0.60, P < .001). In receiver operating characteristic analysis, CVHRS (cutoff of 30 events/h) identified severe SDB with a sensitivity of 82%, a specificity of 77%, and an area under the curve of 0.83. CONCLUSIONS: CVHRS determined by Holter ECG is a useful screening index for severe SDB in subjects with HF.