Not All Progestins Equal for Heart

One kind made attacks more severe, while the other limited damage

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FRIDAY, Oct. 8, 2004 (HealthDayNews) -- The type of progestin used in hormone therapy for menopausal women could affect heart attack severity, says a Wake Forest University Baptist Medical Center study on monkeys.

"One type of hormone therapy limited heart muscle damage to only 5 percent, while another resulted in permanent damage to 35 percent of muscle," lead investigator J. Koudy Williams said in a prepared statement. "If we can learn more about this mechanism, we might be able to identify better hormone therapies for postmenopausal women."

The study was presented Oct. 8 at the North American Menopause Society annual meeting in Washington, D.C.

Hormone therapy has long been used to prevent heart vessel disease in postmenopausal women. But several recent studies found that combination hormone therapy (estrogen plus progestin) increased the risk of both a first and second heart attack.

"These studies didn't look at the amount of heart damage that occurs if a postmenopausal woman has a heart attack. This is important to know because even though the drugs are no longer recommended to prevent heart disease, many women take them for menopausal symptoms or to protect their bones," Williams said.

In this study of postmenopausal monkeys, the researchers compared the effects of the progestin in Prempro with the progestin in Femhrt. One group of monkeys received estrogen and the Femhrt progestin, one group received estrogen and the Prempro progestin. The monkeys were given the drugs for a year in doses equivalent to those prescribed to women. A third group of monkeys didn't get hormone therapy.

The researchers induced heart attacks in the monkeys and measured heart muscle damage. The monkeys in the Femhrt group had 5 percent muscle damage, those in the group that didn't get hormone therapy had 20 percent damage, and those in the Prempro group had 35 percent damage.

The amount of heart muscle damage influences the risk of future heart attack and the risk of developing heat failure.

"We were very surprised. The two progestins produced dramatically different results," Williams said.

But these results are too preliminary to apply to women, Williams noted.

More information

The U.S. National Institute on Aging has more about hormones after menopause.

SOURCE: Wake Forest University Baptist Medical Center, news release, Oct. 8, 2004

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