Postmenopausal Hormone Therapy and Risk of Cardiovascular Disease by Age and Years Since Menopause

April 2007

Findings Summary

The two WHI Hormone Trials of estrogen and estrogen-plus-progestin previously showed that hormone therapy does not reduce the risk of heart attack and increases the risk of stroke. Other WHI publications have suggested possible heart benefits in women aged 50-59 or for those who started hormone therapy less than 10 years after menopause. However, these previous findings were not “statistically significant.”
WHI researchers have published a new analysis of the combined data from the two Hormone Trials to bring the effects by years since menopause into sharper focus. This combined analysis suggests that:
  1. Risk of heart attack from hormones may not be increased in women who start the hormones less than 10 years after menopause, but there is increasing risk in women who are more distant from menopause
  2. Risk of stroke from hormones does not depend on when a woman starts hormone therapy; strokes are increased regardless of years since menopause
  3. Risk of death from any cause appeared to be reduced in women who were 50-59 years at the time they started hormones in the two WHI trials
The increased risk of heart attack in older women appeared to be concentrated in a small percentage (12-17%) of women with persistent hot flashes or night sweats, in part because those women had more risk factors for heart disease (such as high blood pressure, high blood cholesterol, diabetes, and overweight). This increased risk of heart attack did not apply to younger women with hot flashes or night sweats.
These findings may be somewhat reassuring to women who are close to the menopause and considering short-term hormone therapy to treat hot flashes or night sweats. These women do not appear to be at increased risk for heart disease if they take hormones, but they should check their risk factors, especially blood pressure, to avoid the increased risk of stroke. Women using hormones should also have regular mammograms, because the risk of breast cancer while on estrogen plus progestin is increased, even for those women who are less than 10 years after menopause.
Women who are more distant from menopause, however, should be very cautious about using hormone therapy. They have an increased risk of both heart attacks and strokes. If they have hot flashes or night sweats, they should be particularly careful about having their risk factors checked and treated.
This new, combined analysis from the WHI hormone trials does not change the current recommendation that hormone therapy should not be used for prevention of heart attacks. If hormones do not increase risk of heart attack at younger ages—and even if they reduce risk in these age groups--there is no certainty that any benefit will persist with long-term use into older ages.