DEAR DOCTOR K: I’m 68 years old and have been on low-dose estrogen therapy since I had a hysterectomy (and started menopause) at age 50. My doctor won’t prescribe it anymore because he says it increases my risk of heart problems. Is that true?
DEAR READER: The effect of hormone therapy on the heart is a controversial area. Hormone therapy usually involves “combination therapy,” with both estrogens (the main female hormones) and progestins (other important female hormones). Estrogen helps reduce symptoms of menopause, such as hot flashes. Progestin reduces the risk of cancer of the uterus.
In my opinion, combination therapy or estrogen therapy alone probably reduces the risk of heart disease among women entering menopause, and for five to 10 years thereafter. But then combination therapy begins to increase the risk of heart disease.
How could it be that hormone therapy protects against heart disease in younger menopausal women, but increases the risk of heart disease in older menopausal women? It has to do with the effect of female hormones on blood vessels.
The most common type of heart disease is atherosclerosis of the arteries that supply blood to the heart. Atherosclerosis causes cholesterol-filled “plaques” in the walls of the arteries. As these plaques grow, they can block the flow of blood through the arteries. When blood flow to a part of the heart muscle stops, the muscle dies. That’s what happens in a heart attack.
Estrogen slows the development of plaques. By the time a woman reaches menopause, her own natural estrogen has helped protect her against developing plaques. The estrogen in hormone therapy continues to slow (but not stop) plaque development.
By 10 years after menopause, however, the average woman has “vulnerable plaques” –caused by inflammation inside the plaque – that threaten to rupture. Estrogen increases this inflammation, and it causes blood to clot more easily, thus increasing heart attack risk.
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