Estrogen Replacement and Atherosclerosis (ERA) in Older Women

BACKGROUND:

Cardiovascular disease is the number one cause of death in postmenopausal women. Postmenopausal estrogen replacement is associated with a lower incidence of cardiovascular disease in women, especially in those with established coronary artery disease. The strength of the apparent effect of estrogen in epidemiologic studies suggests that estrogen plays a fundamental role in the maintenance of vascular health. Animal data suggest that the current practice of adding the low dose progesterone to prevent endometrial hyperplasia may inhibit the beneficial effects of estrogen on coronary arteries. Before committing millions of postmenopausal women to long-term estrogen use for prevention of coronary artery disease, it is mandatory to demonstrate that it does indeed protect against coronary atherosclerosis, to determine the impact of co-treatment with progestin, and to understand the mechanisms through which estrogen may exert it's cardioprotective effects.

The Office of Research on Women's Health provided $500,000 in Fiscal Year 1995 for recruitment of subjects.

DESIGN NARRATIVE:

Randomized, placebo-controlled, blinded. The minimum diameter of coronary stenotic lesions was measured by angiography before and after three years in a group receiving unopposed estrogen replacement therapy, a group receiving estrogen replacement plus continuous low dose progestin, and a group receiving placebo. The incidence of clinical events was documented in all three groups. Secondary objectives of the trial included examining the effect of chronic and acute estrogen administration on endothelium-dependent coronary vasodilator capacity, plasma lipids and lipoproteins, antioxidant activity, blood pressure, glucose metabolism, and plasma hemostatic factors, as well as on behaviors, physical attributes, and psychosocial parameters. There were four pre-randomization variables in order to pre-stratify. These included current smoking status, insulin dependent diabetes, current lipid-lowering therapy, and the hospital where angiograms were performed.