Estrogen therapy, which has halved coronary artery disease symptoms in postmenopausal women, may hold similar health benefits for men in the same age group, Johns Hopkins researchers have discovered.
In a study published in the Oct. 15 issue of the American Journal of Cardiology, the researchers showed that conjugated estrogens, which contain a variety of estrogen compounds, increased blood flow to the heart by nearly a third in men with coronary artery disease. The finding contradicts prior studies showing that 17ß-estradiol, another form of estrogen, improved coronary blood flow in women only.
"This is the first study to find that middle-aged men may one day benefit from the protective effects of estrogen," says Roger S. Blumenthal, M.D., the study's lead author and an assistant professor of medicine at Hopkins.
Research is now ongoing to develop "nonfeminizing" estrogen compounds that would improve blood flow in men without increasing their risk of breast or other cancer, or produce such feminizing effects as breast enlargement.
For this study, the researchers examined 20 male patients ranging in age from 51 to 61, all of whom had coronary artery disease. Using coronary angiography (X-rays of blood vessels) and ultrasound technology, they measured blood flow response to acetylcholine (an injectable compound used to test whether arteries are healthy) to the heart. Blood flow was measured twice -- before the men were given an intravenous solution of either conjugated estrogens or a placebo, and again 15 minutes after.
In the 12 men who received conjugated estrogens, blood flow to the heart increased by an average of 32 percent. By contrast, there was no change in blood flow among the eight men who received a placebo in place of estrogen.
In previous studies, estrogen has been shown to retard the development of plaque in the arteries and prevent blood clots. Estrogen therapy also is associated with a 10 to 15 percent increase in high-density lipoprotein cholesterol, or "good" cholesterol, and a similar decrease in low-density lipoprotein cholesterol, or "bad" cholesterol.
"Based on these favorable effects, it appears that estrogen may have cardioprotective effects in men as well as women," Blumenthal says.
Research is now being performed to separate the components of conjugated estrogen, which have beneficial effects on blood vessels and no detrimental effects on breast or other tissue.
"Men probably will only be willing to take estrogenic compounds if there are no associated feminizing side effects," Blumenthal says.
The study, which was supported by Hopkins' Ciccarone Center for the Prevention of Heart Disease, included the University of Pittsburgh Medical Center.
The study's other authors were Alan W. Heldman, M.D.; Jeffrey A. Brinker, M.D.; Jon R. Resar, M.D.; Vicki J. Coombs, C.C.R.N.; Sean T. Gloth, M.D.; Gary Gerstenblith, M.D.; and Steven E. Reis, M.D.
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