Severe Sleep Apnea Doubles Risk of Death in Men — Implications for Those with Atrial Fibrillation
August 20, 2009 5:49 AM CT
A study just published in the Public Library of Science, Medicine, reported that men between the ages of 40 and 70 who have severe sleep apnea have twice the risk of death, specifically from coronary artery disease, as men without sleep apnea. Even for men with moderate sleep apnea, the risk of death is 45% higher. The study was unable to draw conclusions about sleep apnea and death in women as there were just too few women with sleep apnea in the study.
Sleep-disordered breathing, or sleep apnea, has been associated with hypertension, coronary artery disease, heart failure, and stroke. It has also been shown to be a risk factor for Type 2 diabetes and insulin resistance. All of these conditions are either risk factors for, or results of, atrial fibrillation.
In addition, sleep-disordered breathing increases vulnerability to sudden cardiac death. While for those without sleep apnea the greatest risk of sudden cardiac death is from 6AM to 11AM, for those with sleep apnea the risk shifts to 10PM to 6AM due to sleep stress triggering arrhythmias. Those with sleep apnea are also more prone to injury and death from vehicle accidents.
This study, which was part of the Sleep Heart Health Study investigating cardiovascular consequences of sleep-disordered breathing, found that sleep apnea independently predicts death and is not associated with other factors, such as obesity or medical condition.
The main reason for this finding is that the level of oxygen in the blood falls when breathing is interrupted. Mild sleep apnea means stopping breathing less than 15 times per hour of sleep, moderate means stopping breathing 15 to 29 times per hour, and severe means stopping breathing 30 or more times per hour. As little as 11 minutes per night of not breathing doubles the risk of death, and this effect is cumulative, building up over decades.
Sleep apnea is believed to impact about one in four men and one in ten women, and most are not aware that they have the problem.
The study didn’t investigate whether using a continuous positive airway pressure (CPAP) machine to keep the airway open, or using another sleep apnea treatment, can reduce the risk of death. This will be a subject of future studies.
I talk a lot about sleep apnea because we know that sleep apnea is a risk factor for afib, and I believe it is way under diagnosed and undertreated in the atrial fibrillation community.
When someone tells me that they wake up in the middle of the night with atrial fibrillation, the first thing I ask is whether they have sleep apnea. When you stop breathing, and then your body startles you awake to get you to start breathing again, it is very likely that the startle response will set off your afib.
We also know that afib patients with untreated sleep apnea are more likely to revert back into afib after electrical cardioversion, so when folks have multiple failed cardioversions, undiagnosed sleep apnea is something to investigate.
I just received the following very heartening message from someone with afib.
“I have had afib for two years, and have been cardioverted twice. As you have commented, a sleep study should be given to see if there is any sleep apnea. I asked the doctor about it, and had a sleep study. The machine is not too bad and my wife is happy I don’t snore any more. And all my heart symptoms have cleared. The quality of my life is back. In my opinion, doctors should do a sleep study FIRST, as soon as the patient can schedule one.”
Treating sleep apnea with a CPAP or other treatment may help afib in some people, though not necessarily all. In the greater scheme of things it’s relatively easy and inexpensive when compared to living with and treating afib. I also find it very heartening that some surgeons and EPs are now requiring sleep studies before doing catheter ablations or surgical procedures.
Somewhat baffling in this study is that over the time of this study, 147 participants reported being treated with positive airway pressure (CPAP) or other sleep apnea treatments, and yet, when they were excluded from the data analysis, the estimates of death risk were virtually unchanged. Was it due to a small sample size relative to the rest of the study, or was there some other factor at work? CPAP can be challenging—some people have difficulty adapting to it, and thus it may be less effective, and some give up entirely, so could those factors have skewed the results?
While we don’t yet know if CPAP or other sleep apnea treatments can reduce the risk of death, it seems logical that if you stop the afib episodes and reduce the risk of stroke, then you’re reducing the risk of death for those with afib. That seems worth asking your doctor about.
One other consideration – the lack of oxygen to the brain leads to Alzheimer’s and dementia. Now are those enough reasons to ask your doctors about sleep apnea?
For more info about this study, see: