By Kathryn Doyle
NEW YORK, (Reuters) - Physically active older women are less likely to suffer from atrial fibrillation, the most common form of irregular heartbeat, than less active women, according to a new U.S. study.
Contrary to suggestions that exercise might raise the risk of abnormal heart rhythms, the analysis based on more than 80,000 postmenopausal women found the risk of atrial fibrillation was lowered by up to 44 percent with regular physical activity.
“This is one of the reasons we ended up doing the study, we wanted to quell some of those concerns,” said senior author Dr. Marco V. Perez of the Stanford Center for Inherited Cardiovascular Disease in California.
“These are women not engaged in extreme forms of exercise, and what we found was that women who engaged in more exercise actually had a lower risk of AF,” Perez told Reuters Health. “The more obese you were, the more you benefited.”
Atrial fibrillation (AF), sometimes shortened to “AFib,” affects more than 1 million U.S. women, and raises their risk of stroke and death even more than it does for men with the condition.
Perez and his team analyzed data from the large, long-term Women’s Health Initiative study. They focused on 81,317 postmenopausal women who had been followed over an average of 11 years.
Using hospital records and Medicare claims, the researchers found that 9,792 of the women developed AF, at an average age of 63.
Higher body mass index, a measure of weight relative to height, increased the risk for AF, as did lower levels of physical activity.
Women who exercised an amount equivalent to five or six 30-minute walks per week or to more vigorous activity like biking twice a week, were 10 percent less likely to develop AF than sedentary women, the authors report in the Journal of the American Heart Association.
“By the time you’re 80, your risk of AFib is about 10 percent, so if you can decrease your risk by 10 percent that is significant,” Perez said.
Obese women were most likely to develop AF, but more physical activity reduced that risk. Obese, sedentary women’s AF risk was 30 percent higher than that of a sedentary woman with normal BMI, and 44 percent higher than that of a normal-weight woman who exercised.
But obese women who exercised had a 17 percent higher risk for AF than normal-weight women who exercised.
There are other benefits as well, Perez said, since AF leads to hospitalizations and healthcare expenditures.
Women who exercise more could also be doing other things that lower their risk of AF, but in the Women’s Health Initiative data he and his team were able to account for education, income and other lifestyle factors, he said.
“Physical activity in itself is known to help reduce cardiovascular risk factors, one of the most important of which is high blood pressure, a known mediator of risk of atrial fibrillation,” said Dr. Usha B. Tedrow, director of the Clinical Cardiac Electrophysiology Program at Brigham and Women's Hospital in Boston.
Exercise is also known to reduce inflammation, which may play a role, Tedrow told Reuters Health by email. She was not part of the new study.
“Atrial fibrillation is a disease where many components of the condition are not under the patient’s control,” she said. “This study suggests one more piece of the puzzle that can allow patients slightly more control over this disease.”
Perez would recommend that postmenopausal women make time for exercise, within reason and under supervision of a doctor if starting a new and strenuous program, he said.
High blood pressure and diabetes are also closely tied to AF, so treating those conditions is extremely important as well, he said.
SOURCE: http://bit.ly/1nbvrQZ Journal of the American Heart Association, August 20, 2014.