Sleep apnea sufferers are at a heightened risk for heart disease, and since continuous positive airway pressure (CPAP) machines are one of the most common sleep apnea treatments, it makes sense that this treatment would help reduce the risk of heart attack and stroke. However, a new study has discovered that using a CPAP machine does not actually reduce the risk of cardiovacular problems.
The study comes from Doug McEvoy, MD, at the Adelaide Institute for Sleep Health at Flinders University in Adelaide Australia, along with other researchers in the Sleep Apnea Cardiovascular Endpoints (SAVE) study. The researchers presented their findings at the ESC (European Society of Cardiology) Congress 2016 and published their report in the New England Journal of Medicine August 28th. Since CPAP machines help treat sleep apnea, and other studies have suggested the machines can benefit the patients, the researchers wanted to discover if the devices really can reduce the risk of heart attack and stroke in sleep apnea patients.
For their study, the researchers recruited 2,717 patients with moderate to severe sleep apnea across 89 clinics and seven countries. Most of the participants were males over the age of 61 who frequently snored, were overweight, and had coronary artery or cerebrovasular disease. These diseases involve problems getting enough oxygen through arteries to the heart or brain, respectively, potentially resulting in a heart attack or stroke later on.
Throughout the three-year study, 1,346 of the participants used a CPAP machine nightly to help keep their airways open as they slept and 1,341 did not. All participants received some care, such as advice on healthy sleep habits and lifestyle changes for sleep apnea sufferers, along with cardiovascular risk management.
The researchers discovered that about 42 percent of the patients using CPAP machines used their device four hours or more per night, on average. The patients did seem to benefit from the treatment as their apnea-hypopnea index (AHI) decreased from 29.0 to 3.7 events per hour. This index indicates sleep apnea severity by measuring the number of times the patient stops breathing as they sleep for more than ten seconds, decreasing the amount of oxygen in their blood.
After about 3.7 years, the researchers followed up with both the CPAP group and the non-CPAP group of study participants. At this time, the researchers looked at how many in each group died from any cardiovascular cause, how many had a myocardial infarction (heart attack) or stroke, and how many ended up in the hospital for heart failure, acute coronary syndrome (reduction of blood flow to the heart, such as angina), or transient ischemic attack (reduced blood flow to the brain). The researchers discovered that 17.0% of the CPAP patients and 15.4% of the non-CPAP patients had a serious cardiovascular problem, such as a heart attack or stroke. There seemed to be no statistically-significant difference between the two groups when it came to cardiovascular problems overall.
Although it makes sense that CPAP treatment would help reduce the risk of heart problems or stroke, since it seems to reduce the number of times a patient stops breathing through the night, the research does not seem to support this. The researchers do not know why, although they speculate it could be because the participants were not using their CPAP machine long enough, and frequently enough, to benefit their cardiovascular system. Future studies could look into whether using the CPAP treatment longer and more frequently can make a difference.
Although the CPAP treatment failed to reduce the risk of heart disease and stroke, it did have its benefits. The CPAP participants seemed to have less daytime sleepiness, better mood with fewer symptoms of depression, higher attendance at work, and an improved health-related quality of life and wellbeing. This suggests that although it may not help their hearts, those with sleep apnea should continue to use their CPAP devices as much as possible.
The continuous positive airway pressure machine, otherwise known as CPAP, is a device with a face mask which forces air into the throat. This air pressure helps to keep the back of the tongue from blocking the pharynx, which is part of the throat, keeping the airways open so someone with sleep apnea can continue to breathe throughout the night. As helpful as the device is for people with sleep apnea, not all patients use their CPAP machine all the time. Many find the device cumbersome when traveling and may be embarrassed about using the machine, and some users may experience nasal congestion or a runny nose.
In obstructive sleep apnea, muscles in the throat may not keep the airways open during sleep, impeding the patient’s ability to breathe. This means that throughout the night, the sleep apnea patient may have their breathing interrupted many times for at least ten seconds each time. Because someone with sleep apnea stops breathing so many times, they may have poor quality sleep and may not be getting enough oxygen into their body. This can make them drowsy throughout the day and increase their risk of heart disease, high blood pressure, memory problems, and poor mood.
Symptoms of sleep apnea can include chronic snoring, sleeplessness, falling asleep during the day, irritability, difficulty concentrating, depression, learning and memory difficulties, and sexual dysfunction. In addition to CPAP, treatment for sleep apnea may include a dental device which repositions the jaw and tongue, surgery, and nerve stimulation. An estimated 18 million adults in the U.S. alone may suffer from sleep apnea.