A distinct ECG-derived spectrographic phenotype is associated with prevalent hypertension, stroke, greater severity of sleep-disordered breathing, and sleep fragmentation in patients suffering from obstructive sleep apnea (OSA), according to a study in the current issue of the journal SLEEP.

Results from the study found that the biomarker, designated as narrow-band elevated low frequency coupling (e-LFCNB), was detected in 1,233 participants (23.5%), with statistically significant differences between those with and without it.

Researchers discovered that the ECG-derived spectrogram's detection of periodic breathing-type respiratory oscillations exceeds that identified by visual detection of periodic breathing. This approach may be a more accurate marker of periodic breathing, they state, because it is automated, objective, and capable of mapping the spectral dispersion of low-frequency, coupled cardiopulmonary oscillations.

Because it makes it possible to track interactions ("coupling") of breathing amplitude and heartbeat rate changes, using an ECG-based technique allows physicians to divide patients with sleep apnea into groups who have or do not have breathing control abnormalities, according to lead author Robert J. Thomas, MD, assistant professor of medicine at the Beth Israel Deaconess Medical Center and Harvard Medical School in Boston.

"Central sleep apnea is precisely timed, meaning that breathing stops and starts with near identical timing from event-to-event," said Thomas, noting in a prepared statement that this type of timing abnormality results in the narrow-band pattern, even if by usual scoring methods, the respiratory abnormality looks obstructive. "We found that having the pattern suggesting a central or breathing control abnormality was associated with worse sleep, more severe sleep apnea, high blood pressure, and an increased risk of prevalent strokes. Therefore, OSA patients who are at increased risk for high blood pressure may be at even greater risk if they also have a control abnormality."