August 19, 2004
One in Four Adults at Risk for Irregular Heart Rhythm
CHICAGO— One in four adults age 40 and older is at risk for developing a heart rhythm abnormality known as atrial fibrillation. What is worse, many of them may not even know they are having symptoms, according to a study in the August 17 issue of Circulation: Journal of the American Heart Association .
Atrial fibrillation is the most common chronic heart rhythm irregularity, affecting about 2.2 million people in the United States. Atrial fibrillation is a major risk factor for stroke, increases risk of death, and reduces quality of life.
About 15 percent of all strokes are attributable to atrial fibrillation, according to the study’s lead author, Donald Lloyd-Jones, MD, assistant professor of medicine and of preventive medicine at Northwestern University’s Feinberg School of Medicine.
In atrial fibrillation, the heart’s two upper chambers (atria) quiver rather than beat effectively. Blood may not be pumped completely out of the atria, and it may pool and clot. If a blood clot leaves the heart and lodges in an artery in the brain, a stroke may result.
“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 the heart rhythms,” said Dr. Lloyd-Jones.
“Thus, a large number of individuals may have atrial fibrillation without being aware of it. We have effective medications for reducing risk for stroke in atrial fibrillation, but if atrial fibrillation goes undiagnosed, we cannot protect people from these potential complications,” Dr. Lloyd-Jones said.
Dr. Lloyd-Jones and co-researchers reviewed data from the Framingham Heart Study, in which a large group of participants had documented examinations, medical histories, and electrocardiograms.
The investigators followed almost 4,000 men and more than 4,700 women from 1968 to 1999. According to the study, about 940 participants developed atrial fibrillation and 2,620 died without prior atrial fibrillation during the study period.
“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,” Dr. Lloyd-Jones said.
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 atrial fibrillation before they die. At age 80, the lifetime risk for atrial fibrillation 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 risk 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 age 40. For a 70-year-old woman, the lifetime risk for breast cancer is one in 14, whereas the remaining lifetime risk of atrial fibrillation is still approximately one in four,” Dr. Lloyd-Jones said.
“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,” he 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, according to Dr. Lloyd-Jones.
At present, the recommendation from the American Heart Association is 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.
This research was funded by the National Heart, Lung, and Blood Institute.