Women with endometriosis at higher risk for heart disease

The study may be the first prospective investigation to examine the link between coronary heart disease and endometriosis -- the growth of the tissue that lines the uterus (the endometrium) -- outside the uterus. Researchers reviewed the records of 116,430 women enrolled in the Nurses' Health Study II. Endometriosis was diagnosed using surgical examinations in 11,903 women by end of follow-up.

During 20 years of follow-up, researchers found that compared to women without endometriosis, women with the condition were:

• 1.35 times more likely to need surgery or stenting to open blocked arteries;
• 1.52 times more likely to have a heart attack; and
• 1.91 times more likely to develop angina (chest pain).

Moreover, women age 40 or younger with endometriosis were three times as likely to develop heart attack, chest pain or need treatment for blocked arteries, compared to women without endometriosis in the same age group.

"Women with endometriosis should be aware that they may be at higher risk for heart disease compared to women without endometriosis, and this increased risk may be highest when they are young," said Fan Mu, Sc.D., the study's lead author, who was a research assistant at Brigham and Women's Hospital and Harvard Medical School in Boston, Massachusetts, when the study was conducted.

Researchers noted that surgical treatment of endometriosis -- removal of the uterus or ovaries -- may partly account for the increased risk of heart disease. Surgically-induced menopause prior to natural menopause may increase risk of heart disease and this elevated risk may be more evident at younger ages.

An estimated 6 percent to 10 percent of women of reproductive age have endometriosis, but exact numbers are unknown since it cannot be diagnosed without surgery. Many girls and women do not realize that distressing menstrual cramps and pelvic pain can be due to endometriosis.

"It is important for women with endometriosis -- even young women -- to adopt heart-healthy lifestyle habits, be screened by their doctors for heart disease, and be familiar with symptoms because heart disease remains the primary cause of death in women," said senior study author Stacey A. Missmer, Sc.D., Director of Epidemiologic Research in Reproductive Medicine at Brigham and Women's Hospital.

The study accounted for oral contraceptive and hormone replacement therapy exposure but could not evaluate details of other hormonal treatments for endometriosis; inclusion of women with endometriosis suspected by clinicians but not confirmed by surgery did not change the results. Despite these limitations, researchers say the large number of patients, length of follow up, and ability to account for many risk factors for heart disease strengthen the findings.