Background Sleep-disordered breathing (SDB) is under diagnosed in chronic heart failure (CHF). Screening with simple monitors may increase detection of SDB in a cardiology setting. This study aimed to evaluate the accuracy of heart rate variability analysis and overnight pulse oximetry for diagnosis of SDB in patients with CHF.
Methods 180 patients with CHF underwent simultaneous polysomnography, ambulatory electrocardiography and wrist-worn overnight pulse oximetry. SDB was defined as an apnoea-hypopnoea index ≥15/h. To identify SDB from the screening tests, the per cent very low frequency increment (%VLFI) component of heart rate variability was measured with a pre-specified cutoff ≥2.23%, and the 3% oxygen desaturation index was measured with a pre-specified cutoff >7.5 desaturations/h.
Results 173 patients with CHF had adequate sleep study data; SDB occurred in 77 (45%) patients. Heart rate variability was measurable in 78 (45%) patients with area under the %VLFI receiver operating characteristic curve of 0.50. At the ≥2.23% cutoff, %VLFI sensitivity was 58% and specificity was 48%. The 3% oxygen desaturation index was measurable in 171 (99%) patients with area under the curve of 0.92. At the pre-specified cutoff of >7.5 desaturations/h, the 3% oxygen desaturation index had a sensitivity of 97%, specificity of 32%, negative likelihood ratio of 0.08 and positive likelihood ratio of 1.42. Diagnostic accuracy was increased using a cutoff of 12.5 desaturations/h, with sensitivity of 93% and specificity of 73%.
Conclusions The high sensitivity and low negative likelihood ratio of the 3% oxygen desaturation index indicates that pulse oximetry would be of use as a simple screening test to rule out SDB in patients with CHF in a cardiology setting. The %VLFI component of heart rate variability is not suitable for detection of SDB in CHF.
- Sleep-disordered breathing
- heart failure
- pulse oximetry
- heart rate variability
- assisted ventilation
- non-invasive ventilation
- sleep apnoea
- lung physiology
- perception of asthma/breathlessness
- COPD mechanisms
- pulmonary embolism
- systemic disease and lungs
- palliative care
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Funding This study was funded by a grant from the British Heart Foundation and supported by the NIHR Respiratory Disease Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London. Ambulatory electrocardiography recorders and heart rate variability analysis software were provided on loan from the manufacturer, Novacor, Paris, France.
Competing interests None.
Ethics approval Ethics approval was provided by Brompton, Harefield and NHLI Research Ethics Committee (COREC 07/Q0404/32).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data collected during this study are stored at the senior author's institution.
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