ANAHEIM, Calif., Nov. 13, 1995 -- Pivotal findings on how estrogen replacement therapy (ERT) helps protect postmenopausal women from heart disease were reported here today in a special session on "Featured Research" at the annual scientific sessions of the American Heart Association.

"Short term ERT appears to decrease the workload of the heart, which may contribute to its heart-protective effects above and beyond its known benefits in improving the cholesterol profile," reported Elsa-Grace Giardina, MD, Professor of Clinical Medicine and Director of the Center for Women's Health at Columbia-Presbyterian Medical Center, in a recent interview.

These findings may help account for the 50 percent lower risk of heart disease seen in post menopausal women who take hormone replacement.

"Our research also suggests that ERT may be of particular benefit to women who are at greatest risk for -- or who already have -- coronary artery disease,"said Dr. Giardina.

Improved understanding of how estrogen works can help physicians better select which women should receive ERT after menopause.

In addition, ERT can aid in the development of new heart-protective medications for men and for those women who can't take estrogen -- medications that might achieve similar benefits.

Estrogen's Mysteries Unfold

While various epidemiological studies have shown that ERT markedly reduces the risk of heart disease in postmenopausal women, the mechanism of this benefit has been unknown.

The Columbia-Presbyterian project was the first crossover study to evaluate the effects of short-term ERT on cardiovascular hemodynamics.

The study enrolled 23 women, whose average age was 57. Seven of these 23 women had coronary artery disease. All were randomized to take for 30 days a daily dose of either 0.625 mg. conjugated oral equine estrogen or an inactive treatment. Then, after four weeks of a washout period, all were crossed over to receive the opposite regimen for another 30 days.

All were evaluated before and after each treatment period, both at rest and during exercise echocardiography, which gives a visual picture of how well the heart is working.

Parameters evaluated included:

-- the heart rate or pulse,

-- blood pressure,

-- cardiac double product -- a measure of heart workload obtained by multiplying the heart rate by systolic blood pressure,

-- left ventricular end-systolic diameter and left ventricular end-diastolic diameter -- measures of how large the heart is when it contracts and expands.

"During exercise, women taking ERT had a lower cardiac double product, indicating that their hearts did not have to work as hard to maintain circulation," explained Dr. Giardina. "Furthermore, smaller left ventricular end-systolic diameters in the women on ERT indicate that the heart chamber is contracting more effectively and emptying more blood with each beat." It is not clear whether this improved contractility is a direct effect of ERT or an indirect benefit caused by the lower systolic blood pressure seen in the women on ERT.

Dr. Giardina pointed out that many cardiac drugs on the market, such as vasodilators and ACE inhibitors, have similar effects, underscoring the value of these mechanisms in improving cardiac survival.

Greatest Benefits for Those at Highest Risk

Women at the highest risk for coronary artery disease, because of high heart rates or workloads, seemed to derive the greatest benefit from the hormone therapy.

For example, while no major change in heart rate was seen at rest in the women as a group, those with the highest resting heart rate at baseline exhibited the greatest reductions with ERT.

"The faster the heart is beating, the harder it is working," said Dr. Giardina. "So this may be another heart-protective mechanism of ERT." In addition, a statistically significant reduction in cardiac double product was seen among those with the highest level at the start of the study.

The findings were presented at the meeting by Millie Lee, MD, a research fellow in cardiology at the Center for Women's Health at Columbia-Presbyterian Medical Center.

Note: The statistics and findings in this release update those found in the abstract (#0614), reflecting the most recent work of Dr. Giardina and her colleagues.

PRESENTATION

Beneficial Cardiovascular Hemodynamic Effects of Estrogen Replacement Therapy in Postmenopausal Women. Millie Lee, Robert Sciacca, Stephanie R. Bruce, Henry Wu, Catherine Tuck, Marco R. DiTullio, Shunichi Homma, Elsa-Grace V. Giardina. Center for Women's Health, Columbia-Presbyterian Medical Center, New York, NY.

NOTE TO EDITORS: To arrange interviews on site contact: Karin Eskenazi of Columbia-Presbyterian Medical Center, SKY PAGER: 1-800-Sky Page Pin # 303-3560.

CONTACT: Karin Eskenazi, 1-800-Sky Page Pin # 303-3560, or Susan Parker, 212-305-5587, both of Columbia-Presbyterian Medical Center