What Causes Atrial Fibrillation?
You're probably wondering where atrial fibrillation comes from or what causes it.
We know that the erratic electrical impulses that cause atrial fibrillation often originate in the pulmonary veins, at least in most paroxysmal (intermittent) atrial fibrillation, and that the impulses that cause persistent and permanent afib are believed to come from other areas as well, but what actually causes afib? Though researchers are investigating the cause, as of now, that cause is unknown.
What Are Atrial Fibrillation Risk Factors?
The risk factors for atrial fibrillation are as numerous as the symptoms.
One of the most important risk factors is existing heart disease. Atrial fibrillation is common among those with coronary heart disease, valve disease, or an inflamed heart muscle or lining, or who have had a heart attack, congestive heart failure, or recent heart surgery. Atrial fibrillation is quite common following valve surgery and coronary artery bypass (CABG), and the incidence can range from 5 to 40 percent following coronary artery bypass.1
Afib can also be found in those with clogged arteries (atherosclerosis) or chest pain (angina), and having diabetes, high blood pressure, or thyroid problems may also increase risk. It's found in people with lung problems, including asthma, emphysema, pulmonary blood clots, or chronic lung disease. 2
In addition, atrial fibrillation can also happen to otherwise healthy people, especially when they are stressed or fatigued, have had too much caffeine or alcohol, or have smoked.
Another known risk factor is having too much or too little of some minerals in your body, such as calcium, magnesium, or potassium. In addition, certain medications, including heart medications, can bring on atrial fibrillation.
As you age, your risk of atrial fibrillation increases. While men are more likely to develop atrial fibrillation, women are more likely to die prematurely from it. Though age is a risk factor, most of the patients we have interviewed started atrial fibrillation in their early fifties, hardly old age, and one even developed afib in the early thirties. It is becoming more and more common at younger ages.
And while some were overweight when afib started, others were not. One even mentioned that the doctor attributed atrial fibrillation to weight, and it went away after gastric bypass surgery, but soon returned, triggered by sinus infection rather than weight, though there may have been pre-existing heart disease.
Obstructive sleep apnea also appears to be a big risk factor, and is on the forefront of recent research. One study indicated that there is a greater risk of atrial fibrillation among those with obstructive sleep apnea — typically overweight males — than with those having other cardiovascular diseases. And afib patients with untreated sleep apnea were more likely to revert back into afib after electrical cardioversion than other afib patients without sleep apnea. 3,4
About half of afib patients have obstructive sleep apnea, a stronger correlation than between afib and any other risk factors. There is also a high correlation between sleep apnea and other heart diseases, as sleep apnea is correlated with high levels of C-reactive protein (CRP), a marker of inflammation that indicates the possible presence of heart disease. It's also possible that afib may cause sleep apnea as well. Afib, obstructive sleep apnea, and obesity all appear to be related conditions, so as we see a surge in obesity, we can expect to see more afib and obstructive sleep apnea. 4
What Triggers Atrial Fibrillation?
When we asked some afib patients about what triggered their afib episodes, most indicated that no one particular thing triggered them, but most mentioned stress as being a major factor.
One was under extreme stress at work, and was in the process of moving across the country when atrial fibrillation started. Doctors blamed it on marginal high blood pressure, which was probably related to the stress.
Another said atrial fibrillation started during a very stressful personal situation while also working in a high-pressure industry, plus just happening to also be "high-strung." Atrial fibrillation went away for a while but came back when the high stress returned. Chocolate and caffeine were also mentioned as possible additional triggers, which isn't surprising as we often consume them when under stress. Some also mentioned exercise as being a trigger.
In addition to stress, having heart disease contributes to atrial fibrillation. Mellanie True Hills, founder of StopAfib.org, was a high tech consultant with a stressful road warrior lifestyle. As she got off a flight, she experienced symptoms of a heart attack, which turned out to be a 95% blockage of a major coronary artery, and she almost died on the operating table. Just seven months later, after another flight, she felt her heart skip a beat, and then got dizzy. Her right leg went cold and the vision in her right eye got fuzzy. She had blood clots (artery clots, not the vein clots associated with "economy-class syndrome" on airplane flights), spawned by atrial fibrillation, and had a close call for a stroke. She doesn't know if it was stress, heart disease, or the change in air pressure from the flight, though it was likely a combination of all. In subsequent episodes, sometimes things as simple as leaning over washing the dog, sitting at her desk working, or taking a brisk walk would trigger an episode.
A big challenge for those with atrial fibrillation is that you never seem to be able to anticipate when an afib episode will happen, but understanding some of the common triggers may give some clues.
1 Russo, Andrea M., MD, "Overview of the Contemporary Evaluation and Management of Patients with Atrial Fibrillation: What Every General Practitioner Should Know" <http://www.americanheart.org/downloadable/heart/1075_russo.pdf>, American Heart Association [Internet], Copyright, 2006.
2 "Living with Atrial Fibrillation" <http://www.heart.org/presenter.jhtml?identifier=9>, American Heart Association [Internet], Copyright, 2006.
3 Kanagala, Ravi, MD, et al, "Obstructive Sleep Apnea and the Recurrence of Atrial Fibrillation" <http://www.circ.ahajournals.org/cgi/content/full/107/20/2589>, Circulation: 2003;107:2589.
4 Gami, Apoor S, MD, et al, "Association of Atrial Fibrillation and Obstructive Sleep Apnea" <http://circ.ahajournals.org/cgi/content/full/110/4/364>, Circulation: 2004;110:364-367.
