Menopause and Heart Disease: Another Myth Dashed

By Adriane Fugh-Burman, M.D.

For decades, women have been told that menopause increases their risk of cardiovascular disease. It has never been true. There is no increase in either diagnosis of cardiovascular disease or heart disease deaths at menopause, nor is there a sharp increase in risk for cardiovascular disease that is related to menopause. Heart disease does become more common as women get older—as it does with men. In other words, aging increases the risk of cardiovascular disease in both men and women, but menopause has nothing to do with it.

Although normal menopause (beginning between the ages of 45 and 55) is not associated with increased cardiovascular risk, for many years, the prevailing medical opinion was that the estrogen produced by the ovaries protected women from heart disease before menopause. Why did this myth persist for so long? The slim piece of evidence upon which it is based is the fact that women who undergo premature menopause (i.e., before the age of 40) are at higher risk of heart disease.

New findings based on data from the Framingham Heart Study—a venerable prospective observational study that started in 1948—turns this theory on its head. The research analyzed data from 695 women who were 34 to 55 at the beginning of the study, and who reached natural menopause during the study. The Framingham Heart Study found that risk factors for cardiovascular disease were associated with undergoing the menopausal transition at an earlier age. Higher cholesterol, increased weight, increasing blood pressure, and smoking all were predictive of an earlier age at menopause. The Framingham Risk Score, which combines several risk factors, also was related to age at menopause. In other words, early menopause doesn’t cause cardiovascular disease, but cardiovascular disease causes early menopause.

Anything that damages or inhibits blood flow to the arteries that feed the heart can increase the risk of a heart attack; similarly, anything that inhibits blood flow to the arteries that serve the brain can increase the risk of a stroke. High cholesterol levels can cause atherosclerosis (a buildup of plaque in arteries, which narrows them); high blood pressure can increase the chance of a clot breaking free and blocking an artery. Smoking can damage blood vessels and also causes constriction which, in combination with narrowed arteries, can restrict blood flow to the heart or brain. The investigators in the recent study based on the Framingham data note that it is possible that the same processes that increase the risk of heart attack and stroke also affect the arteries that feed the ovaries, which shuts down reproductive function early.

In the Framingham study, premenopausal weight was not associated with age of menopause; both increasing and decreasing weight was associated with earlier menopause. This seems like an odd finding but, as the authors note, being overweight increases the risk of heart disease, but losing weight is associated with increased risk. (I would add that chronic disease may cause weight loss and could also be associated with early menopause).

The Framingham study is important because it provides evidence to combat the erroneous concept that menopause accelerates heart disease, a notion that was used to pressure women into taking menopausal hormone therapy. We now know, from the Women’s Health Initiative and other studies, that menopausal hormone therapy doesn’t protect against heart disease (it may actually increase risk), and that it increases the risk of stroke, dementia, and pulmonary embolism (which are blood clots in the lung).

This isn’t just of historical interest. Astoundingly, the myth that normal menopause increases the risk of heart attack is still perpetuated by some physicians who refuse to believe that estrogen is not the fountain of youth. Although estrogen or estrogen-progestin combinations have been shown not to benefit postmenopausal women, a few diehard optimists (usually paid by hormone manufacturers), continue to believe that estrogen will prevent heart disease if started, say, in a woman’s thirties.

We can only hope that the latest study from Framingham will drive a final nail into the coffin of the view that hormones have cardiovascular benefits.

REFERENCE
1. Kok HS, van Asselt KM, van der Schouw YT et al. “Heart disease risk determines menopausal age rather than the reverse.” J Am Coll Cardiol 2006;47(10): 1976-83.

Adriane Fugh-Burman, M.D., is an associate professor in the department of physiology at Georgetown University School of Medicine, and a former chair of the NWHN.