Prior to the early termination of the estrogen plus progestin arm of a nationwide women's health study, postmenopausal hormone replacement therapy was the most commonly prescribed medication in the United States, based on its alleged cholesterol-lowering and cardioprotective effects.

As a result, according to a study in the August issue of Annals of Epidemiology, a large number of women who used hormone replacement therapy may have been at increased risk -- and women who continue to use "unopposed" estrogen replacement remain at risk -- for developing heart problems.

Northwestern University researcher Mercedes Carnethon, who led the nine-year study of 3,100 postmenopausal women selected from the Atherosclerosis Risk in Communities Study, said that estrogen replacement therapy prolongs a segment of the electrocardiogram called the QT interval, a part of the repeating electrical pattern of the heart that is measured in fractions of a second. Prolongation of the QT interval is associated with an increased risk for arrhythmia, coronary heart disease and sudden cardiac death.

Carnethon is assistant professor of preventive medicine at the Feinberg School of Medicine at Northwestern University.

Carnethon and her research group found that odds of QT prolongation were 50 percent higher among women who used hormone therapy as compared with women who never used hormones.

However, when hormone use was compared separately by formulation, risk for QT prolongation was nearly twice that in women who used estrogen replacement therapy compared with those who never used it. There was no difference in risk in women taking progestin plus estrogen vs. those who were not using hormone replacement
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Contact: Elizabeth Crown
e-crown@northwestern.edu
312-503-8928
Northwestern University
28-Jul-2003