Background: Heart disease is a major cause of illness and death in women. To understand better the role of estrogen in the treatment and prevention of heart disease, more information is needed about its effects on coronary atherosclerosis and the extent to which concomitant progestin therapy may modify these effects.

Methods: The investigators randomly assigned a total of 309 women with angiographically verified coronary disease to receive 0.625 mg of conjugated estrogen per day, 0.625 mg of conjugated estrogen plus 2.5 mg of medroxyprogesterone acetate per day, or placebo. The women were followed for a mean (±SD) of 3.2±0.6 years. Base-line and follow-up coronary angiograms were were analyzed by quantitative methods. Follow-up coronary angiograms were obtained after an average of 3.2 years of follow up.

Inclusion Criteria:

• postmenopausal
• not currently receiving estrogen-replacement treatment
• one or more epicardial coronary stenoses of at least 30 percent of the luminal diameter, as measured by quantitative coronary angiography

Exclusion Criteria:

• known or suspected breast or endometrial carcinoma
• previous or planned coronary-artery bypass surgery,
• a history of deep-vein thrombosis or pulmonary embolism,
• symptomatic gallstones,
• serum aspartate aminotransferase level more than 1.5 times the normal value,
• fasting triglyceride level of more than 400 mg per deciliter
• serum creatinine level of more than 2.0 mg per deciliter
• more than 70 percent stenosis of the left main coronary artery,
• uncontrolled hypertension, or
• uncontrolled diabetes.