Low Estrogen Linked To Heart Attack In Premenopausal Women

¡§We found that significantly more premenopausal women experienced their heart attacks during or after their periods when their natural estrogen levels are low,¡¨ says lead researcher Bettina Hamelin, Pharm.D., who is an associate professor of pharmacy at Laval University in Quebec, Canada. ¡§However, these young women also had a number of other important risk factors such as smoking and diabetes.¡¨

This estrogen/heart disease link was first recognized after the long-term Framingham, Mass., cardiovascular study in the late 1970s. After tracking the residents of the town for many years, researchers noted that age 55 seemed to be a magic number for women: before age 55, they seldom had heart attacks, but after 55, the rate increased significantly.

¡§They wondered, of course, what happens at 55 ¡V was it something to do with menopause? The hypothesis states that high levels of estrogen circulating in a woman¡¦s bloodstream may help protect her heart, which could be one reason a woman¡¦s risk of cardiovascular disease increases after menopause, when hormone levels decrease,¡¨ says Hamelin. ¡§We wanted to understand whether the natural increase and decrease of estrogen during a woman¡¦s menstrual cycle prior to menopause are related to the incidence of heart attacks in younger women.¡¨

The Quebec study is testing the theory that large fluctuations of 17ƒ²-estradiol ¡V a form of estrogen that circulates through the bloodstream ¡V alter heart-disease risk enough that female test subjects would report serious heart problems during and immediately after their periods. The study included 28 premenopausal white women in the Quebec area, ages 35-47, who were admitted to the hospital for heart attack or serious chest pain. These women filled out a detailed questionnaire about their disease and medication history, symptoms, hormonal status and risk factors such as family history of heart disease, diabetes, high blood pressure, high cholesterol and smoking.

Twenty of the women reported heart-related problems within five days of the beginning of their period when estrogen levels are at their lowest. The study will continue until at least 50 premenopausal women with heart attacks and known menstrual-cycle history have been recruited.

This project is part of a larger study examining the role of both traditional and genetic risk factors, as well as estrogen, on unexpected heart attacks in women. Researchers will continue to recruit a total of 600 subjects, with and without heart disease, from the French Canadian population of Quebec, which represents a genetically conserved (similar gene pool) population.

¡§Results, however, apply to the general Caucasian population,¡¨ says Hamelin. ¡§The incidence of heart disease has actually increased in women. Women do have heart attacks prior to menopause and get very sick.¡¨

Hamelin says more data is needed to confirm that there is a vulnerable time during the menstrual cycle which may constitute a trigger in women at risk for heart disease.

¡§In the meantime, young women should be made aware of the fact that they may be at risk for heart disease and they should be very concerned about known risk factors such as a family history of heart disease, smoking, high cholesterol, diabetes and obesity,¡¨ she says. ¡§In addition, all women should be counseled about the potential risks and benefits of estrogen replacement therapy consistent with the American Heart Association¡¦s guidelines for both primary and secondary prevention.¡¨

Co-authors of the study include: Julie Methot, M.Sc.; Marie Arsenault, M.D.; Paul Poirier, M.D.; Sylvie Pilote, M.Sc.; Sylvain Plante, M.D.; and Peter Bogaty, M.D.