"Mounting evidence points to the conclusion that HRT can help prevent heart vessel disease – if the therapy begins around the time that the body stops making its own estrogen," said Clarkson. "The question may not be if estrogen helps, but when is the optimum time to begin therapy."
Clarkson, a professor of comparative medicine, reviewed studies that evaluated the cardiovascular effects of HRT. Included were four large trials of postmenopausal monkeys conducted at Wake Forest over the past 12 years. When estrogen replacement was administered at the onset of estrogen deficiency – which compares to the postmenopausal transition in women – there was a 70 percent inhibition of fatty build-up in the heart's arteries. In contrast, when estrogen replacement was delayed for a period comparable to six years in women, there was no benefit on the heart's arteries.
In his lecture, Clarkson emphasized the importance of not basing prescribing practices on one or two studies of older women, but rather, evaluating all available data. After reviewing recent clinical trials, Clarkson concludes that mounting evidence supports the probability that estrogen therapies can serve as a primary prevention against cardiovascular disease.
For example, the Estrogen in the Prevention of Atherosclerosis Trial (EPAT), conducted by Dr. Howard Hodis at the University of Southern California, showed that estrogen slows the progression of atherosclerosis, the buildup of fatty deposits in blood vessels that can cause heart disease, in younger postmenopausal women, says Clarkson.
"Many studies ranging from cell biology to studies of monkeys and women have found strong evidence supporting estrogen's role in inhibiting the progression of atherosclerosis," Clarkson says. "The best results in slowing the build-up of plaque in blood vessels have been seen in women who begin estrogen replacement as soon as estrogen deficiency begins during the perimenopause transition or at menopause."
Two studies examining heart disease in older women have raised questions about the cardiovascular benefits of HRT. In particular, the Heart and Estrogen/progestin Replacement Study (HERS) and the Estrogen Replacement Atherosclerosis (ERA) Trial evaluated the effect of HRT on older women with pre-existing heart disease.
Both HERS, with patients who were 67 years old and ERA, with patients who were 64 years old, found HRT to have no effect on the cardiovascular health of participants. However, these study populations are not the average HRT user – younger women who begin HRT at the onset of menopause.
"It is important for women to discuss their personal health history with their doctor," said Clarkson. "Treatment decisions should not be made on the basis of those studies whose participants may not represent the average younger patient taking HRT."
Clarkson joined other distinguished women's health experts to discuss recent trends in research and clinical practice at the Third World Congress on Controversies in Obstetrics, Gynecology & Infertility held in Washington, D.C., June 20-23. The symposium was conducted as a joint partnership of the Accreditation Council for Continuing Medical Education (ACCME) through the sponsorship of the American College of Obstetricians and Gynecologists (ACOG) and Rogerio A. Lobo, MD. Dr. Clarkson's presentation was part of the "Major Controversies in HRT: CVD & Cancer" symposium sponsored by Wyeth.
Media Contact: Karen Richardson, (336) 716-4453, krchrdsn@wfubmc.edu