HRT May Help Heart, Swedish Research Suggests
Small study finds it reduces enlarged cardiac muscle
WEDNESDAY, May 18, 2005 (HealthDay News) -- In findings that seem to contradict major U.S. research, heart specialists in Sweden report that hormone replacement therapy (HRT) may help improve cardiac function in postmenopausal women.
A small study found that a combination of estrogen and a progestin shrank dangerously enlarged heart muscle, acting much like the ACE inhibitor drugs doctors commonly prescribe for the condition.
"HRT might act as a mild ACE inhibitor," explained senior researcher Dr. Karin Manhem, an associate professor of internal medicine and cardiology at the Cardiovascular Institute of Goteborg University, in Sweden.
The findings run counter to the much-publicized results out of the Women's Health Initiative (WHI), a large, ongoing U.S. trial involving thousands of women. Parts of the trial involving estrogen and HRT were halted in 2002 and 2004 after early results showed increased risks for breast cancer and stroke. WHI researchers also reported finding increased risks of heart attack and blood clots. Use of HRT among American women soon fell dramatically.
In this newest study, Manhem's team tracked the one-year cardiac health of 20 postmenopausal women whose average age was 56; all had high blood pressure and were already receiving antihypertensive medications.
High blood pressure is a major risk factor for a condition known as left ventricular hypertrophy, in which strained heart muscle enlarges to dangerous proportions, greatly raising the risk of heart failure.
Half of the women were randomly assigned to received estrogen plus a progestin called medroxyprogesterone for six months, and then placebo for another six months. The other 10 women received the same regimens but in reverse sequence.
The estrogen/medroxyprogesterone combo is a widely prescribed HRT regimen sold in the United States under the brand name Premelle or Prempro. Manhem's research was funded by the university and had no financial ties to the pharmaceutical industry.
The HRT regimen appeared to benefit women's cardiac health, according to the study, which was presented at this week's annual meeting of the American Society of Hypertension, in San Francisco.
"The main finding is that oral hormone replacement therapy does seem to decrease the left ventricular mass of the heart," Manhem said.
Most interestingly, this benefit was only apparent in women not taking blood pressure medications called angiotensin-converting enzyme (ACE) inhibitors -- drugs that work on a specific chemical system linked to blood pressure.
"So I think -- although I don't know for sure right now -- that HRT might act as a mild ACE inhibitor, in some way interacting with [this] system," Manhem said.
The Swedish researcher believes the study results aren't necessarily at odds with the WHI findings.
"That study started to treat women later in life, at 60 years of age or older," Manhem pointed out. "In our study, the women were 56 years old on average; they weren't as old. Estrogen might lose its ability to act as positively in older women."
Dr. Anthony Grieco, a staff physician in obstetrics and gynecology at the Ochsner Clinic Foundation in New Orleans, said the researchers "did seem to get improvement in muscle mass of the heart" using HRT. "It does sound as if low-dose [therapy] is of beneficial effect," he added.
He noted that although the overall WHI results seem to reflect badly on long-term use of HRT, "actually, within the first five years, you have a reduction [in cardiovascular risk], then after that first five years you may begin to raise the risk overall."
But he stressed that the Swedish study is far too small to draw definite conclusions when it comes to HRT use, even for women in their 50s.
"I don't know as there's anything that will come out of this 20-person study, when we are talking about something as significant as heart disease and hypertension," Grieco said.
Manhem agreed, describing the trial as "more of a hypothesis-generating study." She said a larger, controlled study would be ideal, but "the problem is that it's difficult to set up a large HRT study" with the ominous WHI findings looming in everyone's mind.
In the meantime, she said her group plans to use epidemiological studies to get a better handle on the mechanisms driving hormone replacement therapy's apparent benefit to the heart, at least for younger postmenopausal women.
Much more on the HRT story can be found at the U.S. National Library of Medicine.