A quarter of all adults aged over 40 could develop an irregular heartbeat

A quarter of all adults aged over 40 could develop an irregular heartbeat called atrial fibrillation, according to a report in Circulation: Journal of the American Heart Association.

Atrial fibrillation is the most common heart rhythm disorder in the U.S., affecting more than 2 million adults. The prevalence of the condition is rising and scientists predict that about 5.6 million Americans will have the disorder by 2050. Known causes of AF include abnormalities in the heart’s structure and long-term uncontrolled high blood pressure.

AF occurs when electrical signals in the heart's upper chambers (the atria) are fired in a very fast, uncontrolled manner. Electrical signals then arrive in the heart's lower chambers (the ventricles) in an erratic pattern, creating an irregular heartbeat and affecting the heart’s ability to pump blood. Atrial fibrillation can produce symptoms including palpitations, an unexplained, rapid heartbeat, lightheadedness, or occasionally chest pain. It can also be asymptomatic. AF can lead to complications such as stroke and congestive heart failure. Treatment via drugs, surgery or devices, is designed to slow the heart rate and/or restore normal rhythm, and to prevent stroke. Blood-thinning medications (anticoagulants) are an important means of preventing stroke in AF patients.

“It has been difficult to gauge the public health burden of atrial fibrillation because it is often ‘silent’, meaning some patients do not recognize the change in their heart rhythm,” said Donald M. Lloyd-Jones, M.D., Sc.M., lead author of the study. “Thus, a large number of individuals may have atrial fibrillation without being aware of it. We have effective medications for reducing the risk of stroke in atrial fibrillation, but if AF goes undiagnosed, we cannot protect people from these potential complications.”

Researchers reviewed data from the Framingham Heart Study, in which a large group of participants had documented examinations, medical histories and electrocardiograms (ECGs or EKGs).

The researchers followed 3,999 men and 4,726 women from 1968-99. During the study, 936 participants developed atrial fibrillation and 2,621 died without prior atrial fibrillation.

The researchers found that at age 40, average lifetime risk for atrial fibrillation was 26 percent for men and 23 percent for women. “In other words, about one in four would develop AF before they die,” said Lloyd-Jones, an assistant professor of medicine and preventive medicine at the Feinberg School of Medicine at Northwestern University in Chicago.

At age 80, the lifetime risk for AF did not change substantially despite fewer remaining years of life. The risk was 22.7 percent for men and 21.6 percent for women at that age.

“To put these findings in context, while the lifetime risks for atrial fibrillation was one in four for adults at age 40, the lifetime risk of breast cancer is one in eight for a woman at age 40,” he said.

“For a 70-year-old woman, the lifetime risk for breast cancer is one in 14, while the remaining lifetime risk of AF is still approximately one in four. Atrial fibrillation is predominantly a problem seen in older individuals, who develop it at very high rates, even though they have a shorter remaining lifespan in which to get it.”

After excluding patients who developed AF as a result of congestive heart failure or heart attack, lifetime risk of AF was about 16 percent, which is about one in six people.

“These lifetime risk estimates are useful in assessing the burden of disease in the population, predicting the future burden of disease, and comparing absolute lifetime risks between common diseases,” Lloyd-Jones said.

The high lifetime risks reported in this study underscore the major public health burden posed by atrial fibrillation and the need for further investigation into predisposing conditions, preventive strategies and more effective therapies, he said.

“We support the American Heart Association’s recommendation that people should have their pulse checked by a physician to screen for atrial fibrillation at every doctor’s visit, and at least every two years,” Lloyd-Jones said. “People can also learn to check the regularity of their own pulse to help detect atrial fibrillation.”