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January 11 1994
Media Contact:Joann Rodgers
Phone: (410) 955-8659
E-mail:
Jrodgers@welchlink.welch.jhu.edu
Johns Hopkins cardiologists report preliminary evidence that
supplemental estrogen
affects coronary blood flow in postmenopausal women. Their results
strengthening the links
between estrogen replacement therapy and decreased risk of heart disease in
older women appear in the January issue of the journal, Circulation.
We knew that postmenopausal women taking supplemental estrogen were
likely to
have as much as a 50 percent reduction in morbidity and mortality from coronary
artery disease," says Steven E. Reis, M.D., lead author of the article.
'However, the mechanism of estrogens favorable effect on the heart is
unclear."
Using coronary angiography, the researchers studied the coronary blood
flow of 33
postmenopausal women before and 15 minutes after a high dose of intravenous
estrogen was administered. Coronary flow increased by an average 23 percent in
22 of the women. Placebo given to the other 11 elicited no change.
Further evidence of estrogen's effect on blood flow was found in a
second part of the
study. This time, the researchers studied 15 postmenopausal women and gave all
acetylcholine,
a drug that increases blood flow in normal coronary arteries and decreases
blood flow in abnormal
arteries in much the same way as do exercise and stress. Seven women had
abnormal responses
to the acetylcholine and as a result their blood flow decreased by an average
33 percent. But after researchers administered estrogen, the blood flow
response to acetylcholine tended to return
to normal.
"It appears that the estrogen lessened the abnormal response to
acetylcholine," says Reis. "In doing so, estrogen may raise the threshold for
developing ymptoms of coronary heart disease during stress and exercise."
Because researchers used single, high doses of estrogen for their
studies, the effects of smaller long-term doses must still be evaluated for
similar effects. Meanwhile, the Hopkins doctors warn women
not to increase the amount of estrogen they now take,
"Long-term dosage studies are just beginning says Howard Zacur, M.D.,
Ph.D., director of Hopkins' estrogen consultation service and co-author on the
report, and need to be completed before any further
associations are drawn.
"More than anything," says Zacur, "this study validates the
information we have been giving menopausal
women and women with heart disease. We can now add biological data to the
epidemiologic
studies which have tried to explain some of estrogen's cardioprotective
properties."
According to the American Heart Association, 500,000 deaths due to
coronary artery disease occur in the United States each year, half in women who
have reached or concluded menopause and no longer
naturally produce estrogen in their ovaries.
Other authors on the study include Sean T. Gloth, M.D.; Roger S.
BlumenthaL M.D.; Jon R. Resar, M.D.; Gary Gerstenblith, M.D.; and Jeffrey A.
Brinker, M.D.