Causes and Risk Factors of Atrial Fibrillation

Atrial fibrillation is a fast and very irregular heart rhythm. It is caused by extremely rapid and chaotic electrical impulses originating in the heart's atria (the two upper cardiac chambers). It can develop due to abnormalities of the heart structure that you are born with, or after damage to the heart such as with high blood pressure, coronary artery disease, or a heart attack. But in some people, atrial fibrillation occurs without any heart defects or damage, and it is often seen in people who are older, overweight, and sedentary. Worldwide, atrial fibrillation is one of the most common arrhythmias that doctors see in their practices.

Atrial fibrillation appears to be related to changes that can occur within the atrial muscle, chiefly inflammation, fibrosis, and increased pressure in the atrial chambers. These changes can disrupt the way atrial tissue handles the electrical impulses of the heart, and atrial fibrillation can result.

One condition that produces these disruptive changes in atrial tissue is atrial fibrillation itself. Once atrial fibrillation occurs, it is more likely to come back again—and to get worse as time goes by. Some experts express this as, “Atrial fibrillation begets atrial fibrillation.” This is one reason atrial fibrillation is thought to be a progressive problem, with episodes gradually becoming more frequent and lasting longer as time passes.

Heart Conditions Associated With Atrial Fibrillation

Almost any cardiac disease can increase the stress on atrial tissue, producing the kinds of inflammation and fibrosis associated with atrial fibrillation. The heart problems most likely to be accompanied by atrial fibrillation are:

• Valvular heart disease, especially rheumatic heart disease
• Coronary artery disease
• Heart failure
• Hypertrophic cardiomyopathy
• Congenital heart disease
• Sinus node disease (Sick Sinus Syndrome)
• Other cardiac arrhythmias, especially supraventricular tachycardia (SVT)
• Chronic hypertension

Non-Cardiac Conditions Associated With Atrial Fibrillation

Several non-cardiac medical conditions also greatly increase the risk of developing atrial fibrillation. These include:

• Pulmonary embolus
• Pneumonia
• Diabetes
• Sleep apnea
• Chronic kidney disease
• Hyperthyroidism
• Dysautonomia
• Cardiac surgery

People with any of these medical conditions, whether cardiac or non-cardiac, have an increased risk of developing atrial fibrillation.

Other Risk Factors for Atrial Fibrillation

Age: The prevalence of atrial fibrillation is strongly associated with age. While less than 1 percent of adults under 50 have atrial fibrillation, 9 percent of people 80 or older have it. In a study that followed nearly 4000 Air Force recruits for 44 years, 7.5 percent developed atrial fibrillation as they grew older.

Genetic factors: While the propensity for atrial fibrillation seems to be higher in some families, the genetic contribution to this arrhythmia is very complex. Still, a history of atrial fibrillation in a close relative significantly increases your risk of developing this arrhythmia.

High birth weight: Babies with an increased birth weight appear to have a higher lifetime risk of atrial fibrillation.

Alcohol: While moderate drinking does not commonly trigger atrial fibrillation, binge drinking does so fairly often. Most of the time, atrial fibrillation in drinkers follows a night or weekend of heavy drinking, a condition which is known as “holiday heart.”

Air Pollution: In at least one prospective study, the concentration of particulate air pollution was associated with a higher risk of atrial fibrillation.

Obesity: People whose body mass index (BMI) is greater than 30 kg/m2—that is, those who are classified as being medically obese—have a significantly higher risk of atrial fibrillation than those whose BMI is below 25. Obesity is associated with elevated left atrial pressures, and also with increased pericardial fat (fatty deposits on the pericardium, which is the outside layer of the heart). Both of these factors are thought to contribute to obesity-associated atrial fibrillation.

Sedentary lifestyle: Several studies have now demonstrated that a very sedentary lifestyle can significantly predispose people to atrial fibrillation. Indeed, at least two studies have shown that, in obese, sedentary people with atrial fibrillation, a strict lifestyle modification program that achieved weight loss and physical conditioning significantly reduced, and sometimes eliminated, the risk of subsequent atrial fibrillation.

Caffeine: Despite the fact that doctors often tell patients with atrial fibrillation (and other arrhythmias) to avoid caffeine, studies have failed to demonstrate that caffeine, in quantities typically consumed, has any effect whatsoever on any cardiac arrhythmias.

Familial atrial fibrillation may be a factor in up to 30 percent of cases of idiopathic atrial fibrillation. It may be caused by a single gene mutation or a combination of genes, environmental, or lifestyle risk factors.

KCNQ1 is one gene that has been identified. It is inherited in the autosomal dominant pattern, which means that it affects both men and women equally and if you have the gene you are likely to display the symptoms. Either parent would have atrial fibrillation and any children inheriting the gene are likely to experience atrial fibrillation. This gene directly affects the ability of the heart muscle cells to bring potassium ions into and out of the cell, as is needed for producing the heart rhythm. Other genes have been found that affect ion channels and can cause atrial fibrillation.

Another genetic cause of atrial fibrillation is mutations in genes that affect the development of the heart and muscle cells in the heart before birth. These can affect the structure and the function of the heart.

Some inherited gene mutations work in combination to raise the risk of developing atrial fibrillation. When combined with other conditions such as high blood pressure, diabetes, or atherosclerosis you are at increased risk.

Almost any kind of heart disease or heart structural defect increases your risk of atrial fibrillation. These can be conditions that develop over time or ones you are born with (such as malformed heart valves).

Damage to your heart due to a heart attack, inflammation of the heart muscle or heart lining, or heart surgery is a risk factor for atrial fibrillation. Chronic conditions that damage the heart, especially uncontrolled high blood pressure, raise your risk.

Here are the things everyone should be doing to reduce their risk of cardiovascular disease—and as a result, atrial fibrillation:

• Don’t smoke. Smoking tobacco is probably the most powerful and reliable way to increase your risk of heart disease.
• Keep your weight down.
• Eat a heart-healthy diet. While the “best” diet to prevent heart disease is a point of continuing controversy, most experts now agree that Mediterranean-style diet is good for the cardiovascular system.
• Get plenty of exercise. A sedentary lifestyle is bad for your health in so many ways. We can now add atrial fibrillation to the list.
• Check your blood pressure regularly, and if you develop hypertension make sure it is adequately treated.
• Make sure your doctor is checking your cholesterol levels, and is thinking about whether you need to take action to improve those levels.
• If you drink alcohol, do so only in moderation—and never binge.

None of this advice should sound unusual. You’ve been hearing about it your whole life. What may be new is that this same advice also applies to the prevention of atrial fibrillation.

Other steps that might help reduce the risk of atrial fibrillation include avoiding the outdoors on days of high particulate air pollution, and eating foods high in omega-3 fatty acids (such as fish).

Doctors are just now becoming aware to what extent atrial fibrillation is a lifestyle disease. The typical patient a doctor sees with atrial fibrillation likely has no identifiable underlying cause (that is, no structural heart disease, diabetes, sleep apnea or any of the other conditions just listed). But they are often older, overweight, and sedentary. It is becoming more and more evident that being overweight and not getting much exercise are strongly associated with atrial fibrillation.

Furthermore, researchers have now shown that, in patients who are obese and sedentary, it is possible to greatly reduce or even eliminate atrial fibrillation by instituting a very strict program of lifestyle changes to induce weight loss and improve physical conditioning. These lifestyle-induced improvements in atrial fibrillation are accompanied by measurable improvements in the heart itself—reductions in pericardial fat deposits, and in atrial fibrosis and inflammation. These findings suggest that being fat and sedentary has a direct effect on atrial tissue in a way that makes atrial fibrillation much more likely—and further, that these cardiac effects can be reversed by losing weight and exercising.

Nobody can avoid getting older. But if you work at it, perhaps you can avoid becoming overweight and sedentary. Of course, this is not to say that maintaining a healthy weight and getting plenty of exercise is easy. For many, many people it is exceedingly difficult, possibly the hardest thing they will ever have to do.

A Word From Verywell

While many doctors regard atrial fibrillation as “just one of those things”—something that happens to certain people for no particular reason—all you need to do is look at the list of risk factors to see that there are certainly ways to reduce your risk of having atrial fibrillation.

Most of the things you can be doing to lower your risk of atrial fibrillation are the very same things you ought to be doing anyway to reduce your cardiovascular risk in general. If you take steps to avoid coronary artery disease, heart failure, and hypertensive heart disease, you will also be lowering your risk for diabetes, sleep apnea, obesity, pulmonary embolus, and cardiac surgery. Avoiding all these conditions will eliminate some of the most powerful risk factors for atrial fibrillation.