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SAVE: CPAP does not reduce CV events in patients with CVD, sleep apnea
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In patients with CVD and moderate-to-severe obstructive sleep apnea, treatment with continuous positive airway pressure plus the usual care did not reduce CV events compared with the usual treatment alone, according to data from the SAVE trial.
The findings were presented at the European Society of Cardiology Congress and published in the New England Journal of Medicine.
R. Doug McEvoy, MD, and colleagues randomly assigned 2,717 adults aged 45 to 75 years (mean age, 61 years; 81% men) with CAD or cerebrovascular disease and obstructive sleep apnea to receive treatment with continuous positive airway pressure (CPAP) plus the usual care or the usual care only. All patients used sham CPAP during a 1-week run-in period.
R. Doug McEvoy
The primary endpoint was a composite of CV death, MI, stroke or hospitalization for one of the following: unstable angina, HF or transient ischemic attack. Mean follow-up was 3.7 years.
Among those assigned CPAP, the average time of adherence to therapy was 3.3 hours per night, and mean apnea-hypopnea index fell from 29 events per hour at baseline to 3.7 events per hour at the end of follow-up, according to the researchers.
At the end of the study period, the primary endpoint occurred in 17% of the CPAP group and 15.4% of the usual-care group (HR = 1.1; 95% CI, 0.91-1.32), McEvoy, from the Adelaide Institute for Sleep Health, Flinders University, Adelaide, Australia, and colleagues reported.
There was no difference between the groups in any individual component of the composite CV endpoint, according to the researchers.
However, McEvoy and colleagues found, the CPAP group improved to a greater degree than the usual-care group in the following non-CV metrics: Epworth Sleepiness Scale score (P < .001), Hospital Anxiety and Depression Scale anxiety score (P = .002), Hospital Anxiety and Depression Scale depression score (P < .001), Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) physical component score (P = .002), SF-36 mental component score (P < .001) and European Quality of Life 5 Dimensions Questionnaire score (P = .03).
“Given the level of risk of [CVD] attributed to [obstructive sleep apnea] in previous observational studies, we were surprised not to find a benefit from CPAP treatment,” McEvoy said in a press release. “It’s not clear why CPAP treatment did not improve CV outcomes. It’s possible that, although the average CPAP adherence of approximately 3.3 hours per night was as expected, and more than we estimated in our power calculations, it was still insufficient to show the hypothesized level of effect on CV outcomes.”
He said that, since there was a signal that use of CPAP for more than 4 hours per night reduced cerebrovascular events, “future trials should consider targeting patients with [obstructive sleep apnea] and stroke who can achieve a high level of compliance with CPAP.”
In a related editorial in NEJM, Babak Mokhlesi, MD, from the Sleep Disorders Center, section of pulmonary and critical care, department of medicine, University of Chicago, and Najib T. Ayas, MD, from the Sleep Disorders Program, respiratory and critical care divisions, department of medicine, University of British Columbia, Vancouver, wrote that “CPAP may have a limited effect in patients with well-established [CVD]” and could be more effective for primary prevention.
Mokhlesi and Ayas wrote that while symptomatic patients with obstructive sleep apnea should be offered CPAP, “prescribing CPAP with the sole purpose of reducing future [CV] events in asymptomatic patients with obstructive sleep apnea and established [CVD] cannot be recommended.” – by Erik Swain
References:
McEvoy RD, et al. Hot Line: Preventive strategies 1. Presented at: European Society of Cardiology Congress; Aug. 27-31, 2016; Rome.
McEvoy RD, et al. N Engl J Med. 2016;doi:10.1056/NEJMoa1606599.
Mokhlesi B, Ayas NT. N Engl J Med. 2016;doi:10.1056/NEJMe1609704.
Disclosure: The study was funded in part by the Philips Respironics Foundation. McEvoy reports receiving research equipment grants from Air Liquide and ResMed and speaker fees from Philips Respironics. Ayas reports serving on an advisory board for BresoTec and receiving speaker fees from RHS Medical. Mokhlesi reports receiving personal fees from Itamar Medical and Zephyr Medical Technologies, receiving a grant from Philips Respironics, and providing expert testimony in medical malpractice cases.
Perspective
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C. Michael Valentine, MD, FACC
The implications of this study are limited in the eyes of many due to several factors.
No. 1, the average effective CPAP usage was 3 hours per night, which, in the eyes of many sleep experts, may limit results due to lack of CPAP during early morning REM sleep.
No. 2, despite lack of benefit in overall reduction of cardiac events, there was still improvement in daytime somnolence and quality of life. Would there have been reduction in cardiac events with an average effective CPAP use of 6 hours per night? We do not know yet.
No. 3, I doubt the findings will affect clinical practice, as quality of life and fatigue are important. Perhaps over the long term, we might see weight loss, decreased atrial fibrillation, and other effects that are possible, but not shown in this study. If a patient population is able to maintain good CPAP utilization, I would love to see the long-term effect on weight loss and episodes of AF.
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