WEDNESDAY, Feb. 4, 2009 (HealthDay News) -- A higher resting heart rate can raise the chances of a heart attack in middle-aged women, a new study finds.
"It's pretty well-established for men that higher heart rates are associated with a higher risk for heart attack," said Dr. Judith Hsia, lead author of a report in the Feb. 4 online issue of BMJ. "Until now, that data has been missing for women."
The study used data on 129,135 postmenopausal women enrolled in the Women's Health Initiative. It found that the 20 percent of women who had heart rates of 76 beats a minute or greater had a 26 percent greater risk of a heart attack in a follow-up period of 7.8 years.
"If you divided them into quintiles, there was no increased risk in the first four," said Hsia, who was a professor of medicine at George Washington University when she led the study and who now is with the drug company AstraZeneca. "I would think of it in terms of a threshold."
The additional risk posed by a higher resting heart rate "is not as much as having a higher LDL cholesterol level, but still a good indicator," Hsia said.
Heart rate should be part of a physician's overall assessment of coronary risk in women as well as men, she said.
"They would be doing a global assessment anyway, and this would be one more thing they would take into account," Hsia said.
Heart rate doesn't seem to matter in younger women, she said. But a higher heart rate in a woman over 50 would indicate a need for the recommended lifestyle modifications needed to prevent cardiovascular problems -- a low-fat diet, lower blood pressure, avoiding obesity and more physical activity, Hsia said.
Physical activity is the key element in prevention for these women, said Dr. Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York City.
"It's the same as in an athlete who is well-conditioned," Steinbaum said. "When you exercise, you increase the tone of the autonomic nervous system, which causes a decrease in heart rate and a decrease in blood pressure."
The autonomic nervous system controls such basic body functions as blood pressure and digestion. "Exercise is the most potent medication we have for improving autonomic function," Steinbaum said. "If we say that exercise is essential, we know why a lower resting heart rate leads to a better outcome."
Cardiovascular risk factors for women are listed by the American Heart Association.