Atrial fibrillation is an abnormal heart rhythm that causes the heart to beat in an “irregularly irregular” pattern. Electrical impulses do not follow the usual orderly movement from the heart’s upper chambers (atria) to its lower chambers (ventricles). The ventricles are the chambers that push blood to the rest of the body. When the upper chambers and lower chambers do not beat in a coordinated way, there can be too little blood that is “pushed”, which can lead to a drop in blood pressure. This can cause feelings of faintness (when too little blood is pushed to the brain), racing of the heart (or palpitations), or chest discomfort (when too little blood is sent to the heart), and other problems. In many situations, an individual may be asymptomatic, i.e. not aware that atrial fibrillation is occurring.
Atrial fibrillation is the most common heart rhythm disorder. The likelihood of getting atrial fibrillation increases with older age and in people with diabetes, high blood pressure, coronary artery disease, heart failure, heart valve problems, thyroid disease and lung disease. Obesity, caffeine and heavy alcohol use also are associated with atrial fibrillation. As described below, atrial fibrillation is particularly prevalent in people with sleep apnea.
Symptoms of atrial fibrillation include a sensation that your heartbeat (or pulse) is slower, faster or more irregular compared to usual. It may also cause symptoms of lightheadedness, shortness of breath and feeling too tired or lacking energy to do your daily activities or exercise.
Because of the irregular flow of blood, there is an increased chance of developing blood clots. These can travel to the brain and cause strokes. Although atrial fibrillation is more common in men, women with atrial fibrillation are more likely to have stroke, stroke-related disability and lower quality of life compared to men.
Atrial fibrillation is more common in patients with both obstructive and central sleep apnea. In fact, it is estimated that nearly 50% of patients with atrial fibrillation have sleep apnea.
Sleep apnea can cause drops in blood levels of oxygen and abnormalities in the balance between the parasympathetic and sympathetic nervous system (the latter is the “fight or flight” response). These stresses can causes problems with the electrical firing within the heart that can lead to atrial fibrillation. These stresses can also cause the heart muscle to enlarge or change shape, which can cause electrical pulses to be conducted abnormally, also possibly leading to atrial fibrillation.
Research indicates that patients with atrial fibrillation who undergo cardioversion or catheter ablation—procedures to change the heart’s rhythm from the irregular patterns of atrial fibrillation to a normal, more regular heart rhythm, are more likely to stay in a normal rhythm if they are treated with CPAP (continuous positive airway pressure) therapy. Other research studies suggest that sleep apnea may cause intermittently occurring atrial fibrillation to progress to a more severe disorder, with the abnormal rhythm occurring more frequently or even persist.
Given the close links between sleep apnea and atrial fibrillation, many doctors now consider sleep apnea in patients who have atrial fibrillation. Some cardiologists now even routinely screen their patients for sleep apnea. Patients with atrial fibrillation may want to talk to their doctors about sleep apnea and find out if they may benefit from evaluation and treatment.
Although there are compelling links between sleep apnea and atrial fibrillation, there are very few studies that have rigorously compared outcomes in patients treated with CPAP with those who have not. Therefore, we cannot yet onclusively state that CPAP (vs other factors) is what keeps the heart in normal rhythm in patients treated with CPAP. We also do not know if treatment of sleep apnea prevents the onset of atrial fibrillation. Although there may be great value in screening patients at high risk for both conditions, the overall benefit of such routine screening is not known. Further clarification is also needed to identify the specific aspects of sleep apnea (e.g. low oxygen levels, high carbon dioxide levels, inflammation, autonomic nervous system fluctuations or pressure changes within the chest directly affecting the heart) may lead to atrial fibrillation so that therapies can be tailored accordingly.
Here are some ongoing studies examining sleep apnea and atrial fibrillation (from clinicaltrials.gov):
This article was written by Suzie Bertisch, MD, MPH, Reena Mehra, MD MS, Patty Tung, MD, Beth Israel Deaconess Medical Center, Cleveland Clinic Foundation, in response to one of the top rated research questions on MyApnea.Org, according to our users. Review the original question.