MONDAY, March 28 (HealthDay News) -- The lives of millions of aging Americans are threatened by an irregular heartbeat called atrial fibrillation, which raises their risk for stroke. But a new report finds that the condition doesn't have to arise as often as it does.

In fact, more than half of atrial fibrillation cases could be prevented by curbing common heart risk factors such as high blood pressure, obesity and smoking, a new study suggests.

The irregular heartbeat affects more than 2 million Americans, experts say, and "individuals with atrial fibrillation have a higher risk of having strokes and are more likely to die earlier," noted lead researcher Dr. Alvaro Alonso, an assistant professor of epidemiology and community health at the University of Minnesota School of Public Health in Minneapolis.

However, he said that "maintaining a heart-friendly lifestyle, which has a known beneficial impact on cardiovascular risk factors, will not only reduce an individual's risk of developing heart attacks and other cardiovascular diseases, but it will reduce the risk of atrial fibrillation."

For the study, Alonso's team collected data on almost 14,600 men and women, average age 54, who took part in the Atherosclerosis Risk in Communities Study. That study looked at heart disease among people living in one of four communities in North Carolina, Mississippi, Maryland or Minnesota.

During the average 17 years of follow-up, 1,520 people developed atrial fibrillation, according to the report, which is published in the March 28 online edition of Circulation.

Of these cases, about 57 percent were ascribed to one or more known heart disease risk factors such as high blood pressure, smoking, diabetes, and overweight. High blood pressure was the strongest predictor for atrial fibrillation, and was associated with 24 percent of the cases, the researchers found.

In addition, race and gender also played a role. Among black Americans, over 80 percent had one or more risk factors, compared with 60 percent of whites. In fact, only about 2 percent of blacks had good risk factor profiles compared with 3 percent of white men and 10 percent of white women, Alonso's group noted.

Overall, having one or more heart risk factors accounted for 50 percent of atrial fibrillation cases, the researchers added. For white women with at least one risk factor, the risk of developing atrial fibrillation was 50 percent, for white men it was just over 38 percent.

Among blacks with at least one risk factor, the risk of developing atrial fibrillation was 94 percent for women and 91 percent for men, the researchers found.

Commenting on the study, Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, said that "it has been very well established that high blood pressure, elevated body mass, diabetes, smoking and underlying structural heart disease are risk factors for atrial fibrillation."

So, he added, "These findings further reinforce the important need to maintain healthy blood pressure, body weight, diet, exercise, and not smoking to reduce the risk of atrial fibrillation and other forms of cardiovascular disease."

More information

For more information on atrial fibrillation, visit the U.S. National Heart, Lung and Blood Institute.