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Estrogen Replacement May Help with Heart Disease
By Patricia Ludwig
Estrogen replacement therapy (ERT) can reduce coronary artery calcium deposits in women in their fifties, according to a new study conducted by researchers associated with the Women's Health Initiative (WHI) and published yesterday in the New England Journal of Medicine (NEJM). The study examined 1,064 women who took either estrogen or a placebo for an average of 7.4 years. Only women who had undergone a hysterectomy participated in the trial because taking estrogen alone elevates the risk for uterine cancer. Thus women with uteruses must take a combination of estrogen and progestin to prevent this cancer.
Coronary artery calcium deposits are directly correlated with fatty deposits and can cause artery blockage, thus increasing the risk of future cardiovascular problems such as heart attacks and angina (chest pain on exertion). Contrary to previous findings, this study reported a 30% to 40% decrease in measurable levels of coronary calcium deposits in the women who took the estrogen. Women who consistently took the study pills had even more pronounced results: estrogen users had a 60% decrease in coronary calcium deposits.
Researchers measured these calcium deposits using high-tech heart scans to produce a non-invasive imagery. In addition, the WHI study found that postmenopausal women taking estrogen are 37% less likely to have a heart attack, yet too few subjects participated in the trial to make this finding statistically significant. The study found that estrogen use results in healthier arteries, but more research is necessary to determine if the improvement in arterial health leads to a reduction in heart attack risk.
These results differ from an initial WHI study, which found that a combination of estrogen and progestin elevates risk for heart attack and blood clots. In addition, that study found an increased risk for heart attack among women taking the combination hormones starting ten or more years past menopause. Thus these new findings present a "timing hypothesis," which suggests that estrogen taken near the onset of menopause can help prevent coronary arterial calcium deposits from developing. Ten years after menopause when estrogen levels have been low for an extended period of time, estrogen pills seem to be ineffective in both preventing calcium deposits and reducing already-formed deposits.
A previous WHI study, published in the Journal of the American Medical Association in April 2006, found that taking estrogen alone led to a trend of reduction in the incidence rates of breast cancer, especially those cancers classified as "invasive" and "ductal." Taken together, these two studies suggest that estrogen use can have health benefits, reducing the risks of both heart attack and breast cancer -- an encouraging result for women using estrogen to relieve the symptoms of menopause such as hot flashes. However, the authors of the new NEJM study warn that "hormone therapy should not be initiated (or continued) for the express purpose of preventing cardiovascular disease in either younger or older postmenopausal women."
More research is necessary to see if the beneficial vascular effects of estrogen use persist at older ages. In the meantime, these results give some reassurance to those women using ERT for menopausal symptoms.
Patricia Ludwig is a research intern at the American Council on Science and Health (ACSH.org, HealthFactsAndFears.com).
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