Estrogen therapy does not appear to reduce the risk of heart attack or coronary death in healthy postmenopausal women, although some data suggest a lower coronary heart disease risk in women aged 50 to 59 years.
The study is published in the Archives of Internal Medicine.
The Women's Health Initiative ( WHI ) included two large clinical trials that evaluated whether hormone therapy with estrogen reduces the risk of coronary heart disease in postmenopausal women.
In the part of the study designed to test estrogen therapy alone, 10,739 women aged 50 to 79 years who had undergone hysterectomy were assigned to take either conjugated equine estrogens -- a mix of several estrogens -- or a placebo.
Though researchers had planned to study the women for 8.5 years, the estrogen-only trial was stopped in March 2004 after only 6.8 years because the hormone treatment appeared to increase the risk of stroke.
Judith Hsia, of George Washington University, Washington, D.C., and colleagues analyzed data from the estrogen-only portion of the WHI study.
During the course of the trial, the women taking hormones experienced 201 coronary events, which included heart attacks and coronary deaths, while those taking placebo had 217 events. Overall, the risk was similar for women who took hormones compared with those who did not, though there was a suggestion of lower risk in women age 50 to 59 years.
Among these women ( a total of 1,396 ) who were aged 50 to 59 years at the start of the study, there was no significant reduction in myocardial infarction or coronary death among those taking estrogen.
However, coronary revascularization was less frequent among women taking estrogen, as were several combined endpoints, such as myocardial infarction, coronary death and revascularization.
" This trial may have been unable to demonstrate a significant difference in the risk of myocardial infarction or coronary death by age group because of the low event rate in young women," the authors report.
Source: American Medical Association, 2006