New findings from the Sleep Apnea Cardiovascular Endpoints (SAVE) study found that after three years of treatment with continuous positive-airway pressure (CPAP), a device used to treat obstructive sleep apnea (OSA), there was no significant reduction in cardiovascular risk in patients who have both OSA and heart disease.
Findings were published in the New England Journal of Medicine, as well as presented at the ESC Congress this year.
Primary investigator in the study, Professor Doug McEvoy, MD, notes that this is surprising given the level of cardiovascular risk that has been associated with OSA in prior observational studies. Dr. McEvoy is from the Adelaide Institute for Sleep Health at Flinders University in Adelaide, Australia.
Participants were gathered from 89 clinical centers in seven countries for the SAVE study. All patients had sleep apnea along with moderate-to-severe disease. Most of the participants were elderly with an average age of 61 years. The majority of them were obese males who snore habitually, and all had cerebrovascular or coronary artery disease.
There were a total of 2717 individuals who participated in the study. Each person was randomized to receive typical care alone or the usual care along with the addition of CPAP. Eligibility was determined by whether the participant complied with a minimum of at least three hours of sham-CPAP use each night for a week before the study began.
Typical care was based on national guidelines for heart risk management, in addition to medical advice on how to improve sleep hygiene and habits, along with changing lifestyle behaviors in order to minimize OSA symptoms.
About 42% of those who were given CPAP adhered to the treatment regimen, using it an average of four or more hours every night. There was a decrease in the mean apnea-hypopnea index to 3.7 from as high as 29.0 events per hour when using CPAP. That indicated good OSA control.
After an average followup time of 3.7 years for 1346 CPAP patients and 1341 typical care patients in the final analysis, there was no difference between the two groups with respect to death from heart disease related causes, stroke or myocardial infarction, and hospitalization due to acute coronary syndrome, transient ischemic attack, or heart failure.
More specifically, about 17% of participants in the CPAP treatment group and 15.4% of those in the typical care group had a serious cardiovascular event.
Dr. McEvoy notes that it is currently unclear as to why the CPAP did not help improve cardiovascular risks and outcomes. It is possible, he says, that even with CPAP adherence at approximately 3.3 hours per night, which was as expected and more than the estimated calculations, there is still insufficient evidence to indicate a true measurement of cardiovascular outcomes in relation to OSA and CPAP use.
Of important note, however, is that CPAP improved quality of life and well-being in the participants, which were defined by less daytime sleepiness, better mood (especially depressive symptoms), and focus or concentration at work.
While the researchers state it is a little disappointing not to find cardiovascular risk reductions with the use of CPAP, the results indicate that using it in OSA patients who also have heart disease provides improvement in symptoms. As with all new findings, further research is necessary to determine how to reduce the risk of heart disease related episodes in people with sleep apnea.
Future trials should be targeted towards patients with OSA and stroke, who can also achieve a high level of adherence to CPAP treatment. This is due in part to the findings in this new study that noted a reduction in cerebrovascular events in participants who used CPAP for more than four hours a night.
Rachael Herman is a professional writer with an extensive background in medical writing, research, and language development. Her hobbies include hiking in the Rockies, cooking, and reading.