The therapy showed reduction in nighttime resting heart rate comparable to that of beta blockers.
Esra Tasali, MD
Continuous positive airway pressure (CPAP) has been proven to be an effective therapy for patients with prediabetes who also suffer from obstructive sleep apnea (OSA).
A new study — presented at the 2018 American Thoracic Society (ATS) International Conference in San Diego, CA, this week — reported that patients with the 2 conditions can improve their resting heart rate through the device therapy.
The randomized, controlled trial, led by Sushmita Pamidi, MD, a sleep-based physician at McGill University, placed 39 adults with prediabetes and OSA into either in-laboratory CPAP therapy (26; 66.7%) or on an oral placebo tablet (13; 33.3%). Researchers recorded sleep via polysomnography, and all-night CPAP use was ensured through supervision.
The subjects’ physical activity and heart rates were monitored for 24 hours from baseline and during 14 consecutive treatment days, via an ambulatory device with a tri-axial accelerometer and one-lead electrocardiography (ECG). Researchers analyzed daytime data strictly from rest periods, to ensure control for the effects of physical activity on heart rate.
Nighttime data — which was tracked as from 11:00 PM to 7:00 AM — included only the sleep period excluding all wake epochs. Researchers adjusted results for baseline values and gender.
Patients administered CPAP reported significantly lower daytime resting heart rate profiles versus those on placebo (P = 0.04), with the most notable disparity among patient groups being reported in the second week of treatment. Patients on CPAP also reported similar results during the nighttime (P = 0.002). However, there was no significant difference between patients in daytime activity rates at rest (P = 0.77).
Esra Tasali, MD, senior study author and director of the Sleep Research Center at the University of Chicago, said the effect of CPAP on resting heart rate is comparable to beta blockers: a common heart condition therapy that blocks stress hormones such as adrenaline to prevent the rise of heart rates.
OSA has been previously associated with increased sympathetic activity — meaning it can activate “fight or flight” responses in patients. With prediabetes and higher resting heart rates both being linked to cardiovascular disease, the proven benefits of CPAP was doubly beneficial for researchers. By their count, approximately 80% of all OSA cases in the general US population are undiagnosed.
“OSA is exceedingly common among individuals with abnormal glucose tolerance,” Tasali said. “Our study is a first step in demonstrating that optimal treatment of sleep apnea reduces cardiovascular risk in those with prediabetes.”
Researchers concluded that all-night CPAP therapy markedly reduces 24-hour resting heart rate in this particular population at increased risk of cardiovascular morbidity. With its reduction in rates comparable to that of beta-blockers, the treatment should be considered for analysis into its clinical cardiovascular benefits.