Hormone replacement therapy (HRT) reduces heart disease, right? New research has challenged this assumption, and the benefits may not outweigh the risks of increased breast cancer.

Several years ago, studies suggested that women who take estrogen had fewer heart attacks. These findings were widely publicized, and many women decided to take estrogen on the basis of that information. Now, however, new studies have added confusion to the issue of cardioprotection.

A study called the Women’s Health Initiative (WHI) found a slightly increased risk of heart attack among HRT users in the first two years of the study, but a decline in cardiovascular events later on. A similar increase in risk was reported by the Heart and Estrogen/Progestin Replacement Study (HERS) in postmenopausal women with preexisting heart disease. Likewise, the Estrogen Replacement and Atherosclerosis (ERA) study reached the same conclusion after examining the arteries of women (by angiography) before and after three years of estrogen therapy.

But preliminary results from another study suggest that a particular type of estrogen—17beta-estradiol, a pure form of estrogen that occurs naturally--stops the progression of atherosclerosis to the same degree as the cholesterol-lowering drugs called statins. This finding coincides with other studies suggesting that estrogen improves serum lipid levels and the elasticity of arteries.

Estrogen’s heart-protective properties are still being examined, but most studies now suggest there’s little benefit for women who already have heart disease. Long-term results from the WHI in 2005 will help answer this question. Meanwhile, your best protection comes from reducing risk factors, such as smoking, and maintaining a healthy diet and lifestyle.

Sources:  Harvard Women's Health Watch, April 2001