FRIDAY, Dec. 20, 2002 (HealthDayNews) -- Hormone therapy doesn't prevent a heart attack in postmenopausal women who've previously suffered one, a new British study says.
Researchers based at the University of Manchester in England found that women taking estrogen were just as likely to have a second heart attack as women taking a placebo.
Dr. Nicola Cherry, the study's lead investigator, says the findings reinforce current thinking regarding hormone replacement therapy (HRT).
"At the moment, the U.S. guidelines are that hormone replacement is not recommended for secondary prevention of heart disease and nothing we found in this study would change that," Cherry says.
The results, published in tomorrow's issue of The Lancet, contradict findings from some observational studies that have suggested HRT may protect women from coronary disease.
However, earlier investigators had compared the heart attack rate in women who'd opted to take estrogen with those who decided against taking the hormone, Cherry explains. "So, if the people who chose to take estrogen tended to have less heart attacks, it may be because they also chose not to do other things that might increase their risk, like smoking, for example," she says.
In this latest research, participants were randomly given either estrogen or a placebo, so "all those other factors [in the earlier studies] that might explain why they were doing better or not disappeared," Cherry says.
The researchers recruited 1,017 postmenopausal women, aged 50 to 69, from 35 hospitals in England and Wales. All had recently suffered a heart attack.
Half of them were given a daily dose of oestradiol valerate, an estrogen therapy, and the others were given a placebo for two years.
During the first three months of the study, there were four heart attack-related deaths among women taking estrogen, compared to 12 deaths among those taking the placebo. But by the end of the two years, the difference between the two groups was reduced substantially -- 21 taking estrogen had died of a second heart attack, versus 30 who had been taking the placebo, Cherry says.
Other recent research has indicated that women taking a combination of estrogen and progestin have a slightly increased risk of heart disease. In July, part of the Women's Health Initiative (WHI), a major U.S. study into the long-term effects of HRT, was halted early because of health risks to study participants.
The new study is the first to examine whether taking estrogen alone can cause harm. The results are significant, Cherry says, because while "we didn't find any increased risk, we can't say estrogen had a beneficial effect on the outcome of cardiac deaths either." The evidence adds further weight to the view that HRT should not be prescribed to postmenopausal women solely to protect against heart attacks, she says.
Dr. Margery Gass, a professor of obstetrics and gynecology at the University of Cincinnati and the principal investigator for the WHI's estrogen/progestin trial, says the Manchester study's high attrition rate "could make the benefit of estrogen look less, but it could also make the risk appear lower because fewer people were taking the active treatment." Within three months of the start of the trial, 30 percent of the participants had dropped out of the study; after a year, 50 percent had dropped out.
Gass says when the WHI estrogen/progestin trial was stopped prematurely, some researchers wondered whether the health problems experienced by study participants lay in the mix of the two hormones.
"This [Manchester] study answers the question that taking estrogen alone doesn't offer any cardiac benefit," she says.
What To Do
For more on hormone replacement therapy, visit the National Cancer Institute or the National Institutes of Health.
