WINSTON-SALEM, N.C. -- In a major new study of the effects of hormone replacement therapy (HRT) on heart disease, researchers found that neither estrogen, nor estrogen combined with a progestin, slowed disease progression in 309 older women.
"This study provides additional evidence that HRT may not be as effective as we once thought in slowing heart disease," said David Herrington, M.D., M.H.S., of Wake Forest University Baptist Medical Center. "The message for women and their physicians is to make full use of proven therapies, such as cholesterol-lowering drugs, and not assume that HRT is an effective alternative for treatment of heart disease."
Herrington reported the findings today at the American College of Cardiology's annual meeting. The study, the Estrogen Replacement and Atherosclerosis (ERA) trial, used cardiac catheterization, a test that injects dye into the arteries, to measure narrowing in the heart's arteries caused by a buildup of cholesterol. As vessel disease progresses, these narrowings worsen.
A total of 309 older women with heart disease were randomly assigned to take estrogen (Premarin®), estrogen combined with a progestin (Prempro®), or a dummy pill (placebo). Sophisticated computer techniques were used to measure subtle changes in their arteries over the study period (an average of three years.)
"Overall, there were no differences between the groups in how quickly the disease progressed, " said Herrington, associate professor of cardiology. "HRT did lower cholesterol, but these changes didn't translate into a measurable benefit in the arteries of the heart."
The mean age of the women in ERA was 65.8 years. Almost half (48 percent) of the women were heart attack survivors.
The ERA study provides one more piece to the "puzzle" that scientists are working on about HRT's risks and benefits.
"Based on this study, we can't rule out a small benefit of estrogen, but a dramatic effect as seen with lipid-lowering therapy in patients with high cholesterol, is extremely unlikely," said Herrington.
ERA is the second major clinical study that calls into question the widely held belief that HRT is an effective treatment for heart disease. In 1998, HERS (the Heart and Estrogen/progestin Replacement Study) found that 2,763 women who took estrogen and a progestin for four years had just as many heart attacks as women who didn't take the treatment.
As a result, it was recommended that women with heart disease not begin HRT to lower their risk for future heart attacks and heart disease deaths.
"ERA supports the findings of HERS. In both studies, there was no clear-cut evidence of benefit in women with established heart disease," said Herrington. He pointed out that the results don't necessarily apply to younger, healthier women.
"Other studies, such as the Women's Health Initiative, are looking at the effects of HRT in younger women. These studies will further clarify what role, if any, HRT may play in the prevention of heart disease."
ERA study sites were at Wake Forest University Baptist Medical Center, Forsyth Medical Center in Winston-Salem, Moses Cone Hospital in Greensboro, Carolinas Medical Center in Charlotte, Hartford Hospital in Hartford, Conn., and the University of Alabama at Birmingham. The study was funded by the National Institutes of Health.
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