Hormone therapy may lower heart attack risk

Canadian Press

TORONTO — Research into the benefits and risks of hormone replacement therapy has been a see-saw affair that has often left women more confused than elucidated. But a new analysis of findings from a major U.S. study appears to offer some good news - at least for the more junior of post-menopausal women.

Re-analyzing data from the Women's Health Initiative (WHI), researchers found that taking estrogen seems to lower the risk of heart attack and other cardiovascular conditions in women of one age group: those in their 50s who begin treatment soon after menopause.

The landmark WHI study of women aged 50 and older originally concluded that various combinations of hormone replacement therapy (HRT) did not protect post-menopausal women from cardiovascular disease and in some cases had the opposite effect.

The estrogen-only arm of the study, which followed almost 11,000 women for nearly seven years, was halted in March 2004 (a year early) when researchers found that giving the hormone raised a woman's risk of suffering a stroke. (Other research has suggested that HRT may also increase the risk of breast cancer for some women.)

The WHI's overall finding was based on all the women in the study, no matter their age - and it led doctors to reconsider the long-held belief that prescribing hormones for women would not only alleviate menopausal symptoms but also help prevent heart attacks.

The latest analysis has put yet another twist on HRT's possible benefits.

"Overall, the findings are that the women who were 50 to 59 did show signs of a reduced risk of heart disease," said Dr. JoAnn Manson, head of preventive medicine at Brigham and Women's Hospital and a study co-author. "The findings suggest that there may be differences in the heart outcomes with estrogen therapy depending on age and time since menopause."

The analysis found that women in their 50s who were given estrogen alone had a 45 per cent reduced risk for clogged arteries that required such procedures as coronary bypass surgery or angioplasty, compared with women given a placebo.

When it came to heart attacks, the women on estrogen had a 37 per cent lower risk versus those on placebo and a 35 per cent drop in risk for heart attack, bypass and angioplasty combined, said the study published in Tuesday's Archives of Internal Medicine.

"In contrast, looking at the older age groups ... there was no sign of a reduced risk of heart attack or coronary bypass surgery or angioplasty or any of the heart disease endpoints in those older age groups," Manson said in a teleconference from Boston.

Dr. Mitchell Harman, chief investigator of a soon-to-begin U.S. study that will look at hormone therapy in recently menopausal women, said previous animal and human research projects suggest estrogen can protect against cardiovascular disease if it is begun early enough.

"But once the disease is there, perhaps the effect of estrogen is no longer beneficial in that you can't prevent disease that's already present," said Harman, director of the Kronos Early Estrogen Prevention Study, or KEEPS.

The study of 720 U.S. women will compare the effects of giving estrogen orally and through a skin patch in preventing arteriosclerosis (hardening of the arteries), a major risk factor for heart attack and stroke.

"I think there's mounting evidence from a number of sources now that there may be differences in heart outcomes in younger and older women closer to menopause versus more distant from menopause," he said.

"And this (provides a) window of opportunity for younger women to perhaps receive some heart benefit from hormone therapy."

Still, the new finding will not alter North American hormone therapy guidelines, said Manson. "We do still believe that hormone therapy should not be used for the express purpose of preventing cardiovascular disease in post-menopausal women and we believe the current guidelines to use for menopausal symptoms should hold."

The Society of Obstetricians and Gynecologists of Canada last week updated its position on HRT, saying that women with moderate to severe symptoms of menopause could be prescribed the lowest effective dose for "the appropriate duration."

Manson said the new analysis "may be somewhat reassuring to younger women who are considering hormone therapy" for menopausal symptoms such as hot flashes, night sweats and mood swings.

"However, we do believe strongly that the pendulum should not swing back to starting hormone therapy in older women or in women who are at increased risk of heart disease," she said.

"I think the view that hormone therapy is good for all women or bad for all women is an oversimplification and we really need more research to improve our understanding of the benefits and risks of hormone therapy, especially when started early after menopause."