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What Causes Atrial Fibrillation?

Where does atrial fibrillation come from and 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 longstanding persistent atrial fibrillation are believed to come from other areas as well, but what actually causes afib? Though researchers are investigating the cause of atrial fibrillation, as of now it is largely unknown except that some recent studies have shown a genetic component as afib often runs in families.

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), the incidence of which 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, have smoked, or have exercised too much. Other causes that are frequently mentioned include heart and other medications, recreational drugs, air pollution, chemicals and pesticides, and H. Pylori, which is often associated with ulcers. Another known risk factor is having too much or too little of some minerals in your body, such as calcium, magnesium, or potassium.

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, many people start into atrial fibrillation in their early fifties, hardly old age, and quite a few in their thirties and forties. It is becoming more and more common at younger ages, including young people in their teens and twenties.

Being overweight is often mentioned as a risk factor for afib, but normal and underweight people have it, too. One woman's doctor attributed her atrial fibrillation to weight, and it went away briefly after her gastric bypass surgery, but it soon returned, triggered by a sinus infection.

We are now learning from a number of studies about atrial fibrillation in families as recent research has found genetic clues about why afib runs in some families. To learn more, see Mayo Clinic Finds Gene Mutation Responsible for Atrial Fibrillation That Runs in Families and New Genetic Cause of Atrial Fibrillation Found.

Finally, 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 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, too.4

For more about atrial fibrillation and sleep apnea, see Caution For Those With Atrial Fibrillation Related to Sleep Apnea, Why Afib Patients Must Know Whether They Have Sleep Apnea, and Noted Electrophysiologist and Ablation Pioneer Discusses New Findings About Atrial Fibrillation and Obstructive Sleep Apnea.

What Triggers Atrial Fibrillation?

When we asked some afib patients about what triggered or brought on 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, as it did in the case of Mellanie True Hills, founder of StopAfib.org, when she 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 blurry. 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 of them. In subsequent episodes, sometimes things as simple as leaning over to wash the dog, sitting at her desk working, or taking a brisk walk could trigger an episode, but other times those same triggers didn't bring on afib.

A big challenge for those with atrial fibrillation is that they never seem to be able to anticipate when an afib episode will happen, so understanding some of the common triggers may give some clues.

The concept of triggers, however, is frequently controversial in the afib community. When taken to an extreme, tracking triggers could lead you to cut out things that you might think caused an episode only to find out that some of those triggers really weren't issues at all. At the Atrial Fibrillation Blog you will find some interesting discussions about commonly-cited triggers, including:

To learn about diagnosing atrial fibrillation, see How to Know It Is Atrial Fibrillation.

1 Russo, Andrea M., MD,"Overview of the Contemporary Evaluation and Management of Patients with Atrial Fibrillation: What Every General Practitioner Should Know", American Heart Association, Copyright, 2006.

2 "Atrial Fibrillation", American Heart Association, Copyright, 2009.

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://www.circ.ahajournals.org/cgi/content/full/110/4/364>, Circulation: 2004;110:364-367.

Last Modified 7/06/2012

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