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Key takeaways:
- A study of 150 patients with atrial fibrillation found that sleep apnea alters heart rate variability more during wakefulness than during sleep.
- The findings suggest that daytime monitoring and optimally timed medications could improve atrial fibrillation care for patients with sleep apnea.
- Using CPAP therapy improved patients’ sleep apnea and normalized overall heart rate variability.
- The research team is now launching a randomized, controlled trial to test how CPAP directly affects atrial fibrillation.
Disordered sleep might harm the heart more during the day than at night, according to a study published in the Journal of Arrhythmia. The findings could help improve the treatment of atrial fibrillation.
Over time, sleep apnea increases the risk of heart conditions, making individuals two to five times more likely to have an irregular heartbeat, particularly atrial fibrillation.
To understand the relationship between sleep apnea and atrial fibrillation, a research team evaluated a cohort of 150 people with atrial fibrillation as part of the Sleep Apnea and Atrial Fibrillation Biomarkers and Electrophysiologic Atrial Triggers (SAFEBEAT) project. The team used electrocardiography to track heart rate variability, a measure of how the time between heartbeats fluctuates. They tested the patients for sleep apnea and treated those who had it with CPAP.
The researchers expected heart rate variability to be more abnormal while people were sleeping, when sleep apnea occurs.
“But what we found is that these measures are altered more during wakefulness,” says Reena Mehra, MD, MS, a professor of medicine and head of the division of pulmonary, critical care, and sleep medicine at the University of Washington School of Medicine, in a release.
This unexpected result could be because the effects of sleep apnea on the heart build up over the course of the night and do not peak until daytime. It could also be attributed to people being more active during the day, making the effects more pronounced.
These findings could change how clinicians diagnose and treat atrial fibrillation. Daytime monitoring might be important for these patients, and medications for atrial fibrillation might work better if they are timed to be most effective during daytime hours.
After using a CPAP machine, patients’ sleep apnea improved, and overall heart rate variability became more normal. The researchers note that treating sleep apnea might be an important component of atrial fibrillation care.
Following this exploratory study, Mehra is beginning a randomized, controlled trial to test how CPAP affects atrial fibrillation. The team is also studying whether biochemical signatures of sleep apnea and atrial fibrillation are detectable in patients’ blood.
The study was supported by a grant from the National Institutes of Health National Heart, Lung and Blood Institute.
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