That's what new research from the National Institutes of Health (NIH) found with 226 postmenopausal women who were tracked for almost six years. High systolic blood pressure -- the greatest pressure the heart produces as it contracts -- is considered a precursor to heart attacks, strokes and kidney failure. In the study, diastolic blood pressure -- the least pressure the heart produces as it relaxes -- was not greatly affected.
"Systolic pressure is a major culprit in causing heart disease," says Jerome Fleg, co-author and staff cardiologist at the National Institute on Aging, which is part of NIH. "We think it might be causing some structural changes in arteries. That's why this is significant. Obviously, we'd like to see this confirmed in randomized trials, but it looks like an added effect of hormone replacement therapy [HRT]."HRT's role in preventing cardiovascular disease has been the subject of heated debate in recent years. While the American Heart Association recently issued an advisory that told women not to take HRT just to prevent heart disease, some studies have linked HRT to lower cholesterol levels, which in itself may lower heart attack risk. Other research has found HRT also helps memory and prevents bone loss.
Doctors have linked the increase in heart attacks in older women to the drops in estrogen levels that accompany menopause, and a large-scale study on how estrogen affects the development of heart disease is under way at NIH. Called the Women's Health Initiative, it should be completed by 2005. In 1998, researchers on the Heart and Estrogen/Progestin Replacement Study found that 2,763 older women who took both estrogen and progestin for four years had just as many heart attacks as women who didn't take the therapy.
Fleg thinks part of the problem has been that most of the research has looked at women who have already developed the beginnings of heart disease.
"Maybe it's better as a primary, first line of treatment, early on," he says of HRT. "Maybe we should focus on women before they develop heart disease."
In the most recent study, scientists tapped into the 932 women who are part of the Baltimore Longitudinal Study on Aging for their research; 332 of those women were postmenopausal, with a mean age of 64. Of those, 52 were excluded because they only used estrogen now and then, 28 because they had signs of cardiovascular disease and 26 because they had incomplete records. Of the remaining 226 women, 149 had never used HRT and 77 used a combination of estrogen and progestin regularly. The Baltimore study, begun in 1958, is the longest-running scientific study of aging, according to the NIH.
The women received checkups almost every two years, and the results of the latest visits surprised researchers. Those who used HRT had no significant change in their systolic pressure, while those who didn't use HRT had significant increases in systolic pressure. And only 13 percent of HRT users had become hypertensive, while 16 percent of those who did not use HRT had become hypertensive -- which means your systolic reading (the upper of the two numbers commonly used) exceeds 160 millimeters of mercury and your diastolic reading (the lower number) exceeds 95 mm. Among these hypertensive women, HRT users had an average systolic blood pressure reading of 169.8 mm, while nonusers had an average systolic blood pressure reading of 172.2 mm. Generally, a reading less than less than 140 over 90 means you shouldn't worry.
"I think it's very interesting," says Michelle Warren, director of the Center for Menopause, Hormonal Disorders and Women's Health in New York City. "It's new in that no one else has found this change in blood pressure between hormone users and nonusers. We've been struggling with this issue, but there's evidence that women on hormones do better and live longer. If you take hormones, you have less chance of dying. This may be one of the variables that explains why women on hormones have less risk of dying."
"Once you start looking at markers for heart attacks, and blood pressure is certainly a big one, then you start looking at [cardiac] events," she says. "Maybe we should look at women who start it [HRT] early and use it consistently."
Warren did note that the study was small, and a larger study might now be in order. But that doesn't dampen her enthusiasm for the results.
"We now have a finding, which might explain why certain groups of women on hormones do better and don't die as young. It would suggest that if you use it consistently early, and you get older, it may have significant benefits with systolic blood pressure. There's new questions, new issues here, and new doors."
What To Do
For details on women's cardiovascular risks, go to the American Heart Association.
To find out more about the Baltimore study, and even how to apply for it, take a look at this NIH site.