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.