CPAP may improve heart rate in patients with OSA, prediabetes
All-night continuous positive airway pressure (CPAP) treatment significantly reduced 24-hour (ie, daytime and nighttime) resting heart rate (HR) in patients with obstructive sleep apnoea (OSA) and prediabetes, according to a study presented at ATS 2018 held in San Diego, California, US.
OSA is prevalent in patients with prediabetes, who have an increased risk of developing cardiovascular (CV) disease and death, said lead author Dr Sushmita Pamidi from the Division of Respiratory Medicine at the McGill University Health Centre in Montreal, Quebec, Canada. “[The] combination of [OSA] and prediabetes may translate to an even further increased risk of CV disease.”
Moreover, resting HR is an important predictor of mortality in individuals with and without heart disease, with studies showing an increased mortality risk with a higher resting HR. [Am J Cardiol 2009;103:279-283; Am Heart J 1987;113:1489-1494; JAMA Cardiol 2018;3:200-206]
To determine if CPAP may be beneficial in improving HR, 39 participants with prediabetes and OSA (apnoea-hypopnoea index [AHI] >5) were randomized 2:1 to either in-laboratory CPAP or a placebo tablet for 2 weeks. Nightly polysomnogram was recorded in the sleep lab (with an enforced 8-hour bedtime) and all-night adherence to CPAP was continuously monitored. Participants were allowed to engage in normal daily activities during the daytime and were not confined to the lab. Resting HR was monitored 24 hours/day for 14 consecutive days. [ATS 2018, abstract A1044]
After adjusting for BMI, age, gender, and AHI, mean HR profiles during sleep were significantly lower with CPAP vs placebo (p<0.001).
“[There were] diversions between the two profiles even in the first week but this [became] more pronounced during the second week of treatment,” said Pamidi.
HR variability also improved in the CPAP group vs the placebo group during night time even after adjusting for potential confounders (p=0.02).
During daytime rest periods, there was also a substantial reduction in mean HR in the CPAP group vs the placebo group (p<0.001); however, heart rate variability was no longer significant (p=0.18).
“The effect of CPAP on resting [HR] is comparable to using beta blockers,” said Dr Esra Tasali, senior study author and director of the Sleep Research Center at the University of Chicago in Chicago, Illinois, US. Beta blockers block stress hormones such as adrenaline, which raises HR, she added.
The findings supplement the results reflecting other favourable outcomes of CPAP treatment in the same cohort such as improved glucose metabolism and insulin sensitivity, and reduced plasma norepinephrine levels, which is a marker of sympathetic activity. [Am J Respir Crit Care Med 2015;192:96-105]
“[I]ncreased sympathetic activity … activates our ‘fight or flight’ response [which], in turn, raises our [HR],” said Pamidi. Therefore, these HR reductions may suggest clinical CV benefit, she added, recommending larger, long-term evaluations to determine if these findings represent CV benefit in the long term.