Risk Score May Predict Abnormal Heart Rhythm

THURSDAY Feb. 26, 2009 -- Weighing a combination of risk factors could help doctors predict which patients are the most likely to develop atrial fibrillation, a new study suggests.

To that end, the researchers have developed a risk score that might one day help prevent what has become the most common type of abnormal heart rhythm in the United States, affecting about 2.2 million people.

"We know a lot about the prevention of many different types of vascular disease, but there has been very little attention paid to preventing AF," said lead researcher Dr. Emelia Benjamin, a professor of medicine and epidemiology at Boston University School of Medicine.

But attention might be warranted, since the condition is on the increase in the United States. By 2050, almost 16 million Americans will have AF, Benjamin said. This dramatic increase is partly due to people living longer, so they are more likely to get diseases associated with aging. In addition, people with heart disease are living longer, she explained.

The condition causes the upper chambers of the heart to beat erratically, which hinders the heart's ability to pump blood. It can increase the risk of stroke, heart failure and dementia, and although it can be controlled with medication or surgical procedures, there is no way yet to keep it from developing, according to the American Heart Association.

The risk factors for AF are known, but they tend to be looked at one at a time, and there has been no way of predicting an individual's risk for the disease, Benjamin said. "We developed a risk score for new-onset AF that would work in a doctor's office, or a person could use it to figure out their risk of AF," she said.

The risk factors for AF include older age, being male, being overweight, hypertension, having a heart murmur and a history of heart failure, Benjamin said. "These have previously been described, but not put together in a risk score," she said.

The report is published in the Feb. 28 issue of The Lancet.

For the study, Benjamin's team, which included Dr. Renate Schnabel from the Johannes Gutenberg-University in Mainz, Germany, collected data on 4,764 people who participated in the Framingham Heart Study. These individuals were aged 45 to 95 and did not have AF. The selection of people for the study was made from examinations done between June 1968 and September 1987.

Over 10 years of follow-up, 10 percent of the people developed AF. The strongest factors that predicted the risk of developing AF were age, sex, weight, high blood pressure, being treated for high blood pressure, heart murmur and heart failure. In addition, the time between the P and R waves (PR interval), as seen on an electrocardiogram, was also a significant predictor of AF, the researchers found.

The risk of AF varied with age. Those over 65 were more than 15 times more likely to develop AF than people under 65, the researchers noted.

This risk score may help doctors and patients determine the risk for AF, Benjamin said. More important, this risk score might help doctors develop a way to prevent AF, she said.

"Before you can prevent something, you have to know how to predict it," Benjamin said. This risk score will be useful first to help patients understand their risk, second to provide information for clinical trials, and third to evaluate other ways of predicting AF, she said.

Dr. David Brieger, an associate professor from Concord Hospital at the University of Sydney in Australia and author of an accompanying journal comment, said this study could be a first step in finding a way to prevent AF.

"It may be possible to identify strategies, pharmacologic and others such as lifestyle, to prevent the onset of atrial fibrillation in high-risk patients," Brieger said.

Atrial fibrillation is a potentially disabling condition that is increasing in frequency and placing an increased burden on health care resources, Brieger noted. "Preventing this condition would have immense value. Identifying patients at high risk of developing the condition is an important initial step in this process," he added.

Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, said it is not clear how this risk score would change clinical practice.

"While helpful from a research standpoint, the potential clinical utility of this risk score requires validation in other populations and further study," Fonarow said. "It remains untested whether detection of increased risk of AF will result in any change in care or improve clinical outcomes."

More information

For more about atrial fibrillation, visit the American Heart Association.

Posted: February 2009


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