DALLAS, March 7 - Having a heart attack is damaging enough for elderly Americans, but if they also have an irregular heartbeat known as atrial fibrillation, outcomes are even worse, according to a new study in today's issue of Circulation: Journal of the American Heart Association.
Researchers examined 106,780 people over the age of 65 who had a heart attack. More than 1 in 5 (22 percent) had atrial fibrillation - either prior to their heart attack or immediately following it. Having the condition was associated with higher rates of death and disability following a heart attack in the short-term (in hospitals or within the first month) and the long-term (over the course of a year).
"We didn't think atrial fibrillation would be as common as we found it to be," says the study's senior author, Allen J. Solomon, M.D., associate professor of medicine at Georgetown University Medical Center, Washington, D.C. "When elderly heart attack patients have atrial fibrillation, they are at increased risk for having a stroke, congestive heart failure or a second heart attack. Their hospital stay is also longer."
Investigators found that people who had atrial fibrillation were more likely to have had a prior stroke and advanced heart failure. When compared to heart attack patients who did not have atrial fibrillation, the toll was much heavier on those who did. Death rates were higher in-hospital (25.3 percent with atrial fibrillation died vs. 16.0 percent without atrial fibrillation); after 30 days (29.3 percent vs. 19.1 percent) and after one year (48.3 percent vs. 32.7 percent).
Atrial fibrillation is an irregular heart rhythm, or arrhythmia, affecting about 2 million Americans. When atrial fibrillation occurs, the two small upper chambers of the heart, called the atria, quiver instead of beating effectively. Blood isn't being pumped completely out of these chambers when the heart beats, which can cause the blood to pool and clot. If a clot leaves the atria and becomes lodged in an artery in the brain, a stroke may result. About 15 percent of strokes occur in people with atrial fibrillation.
Because atrial fibrillation is a common complication of heart attack in elderly people and increases the risk of death - particularly when the irregular heartbeat occurs during hospitalization - Solomon says greater attention may be warranted in managing the condition in older Americans.
He adds that this study gives a better view of heart health issues affecting older Americans, a population that has not been studied extensively over the years.
"For decades, the elderly have been excluded from study populations," says Solomon. "They have their own set of complications, many of which are different than those seen in younger populations.
"Elderly patients tend to have more extensive coronary artery disease, more risk factors for a heart attack, such as hypertension and diabetes, and more prior heart attacks and strokes that put them at risk for future heart attacks. There are special situations exclusive to the elderly we need to be concerned about."
In the study, 23,565 patients were found to have atrial fibrillation. Just over half of that group developed the irregular heartbeat in the hospital after their heart attack. The remainder already had atrial fibrillation prior to the heart attack. Researchers are unsure of the exact mechanism that can trigger atrial fibrillation in heart attack patients.
"Our current goal is to learn how to prevent this heart rhythm abnormality and gain a better understanding of the optimal treatment strategy," says Solomon.
Co-authors are Saif S. Rathore, A.B.; Alan K. Berger, M.D.; Kevin P. Weinfurt, Ph.D.; Kevin A. Schulman, M.D., M.B.A.; William J. Oetgen, M.D., M.B.A.; and Bernard J. Gersh, M.B., Ch.B., D.phil.
For more information about atrial fibrillation, visit the American Heart Association's online Heart and Stroke A-Z Guide at http://www.americanheart.org. You can also learn more about how atrial fibrillation can cause a stroke by visiting the American Stroke Association's Web site at http://www.strokeassociation.org.
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