Estrogen and Progestin, Lipoprotein(a), and the Risk of Recurrent Coronary Heart Disease Events After Menopause

CONTEXT Lipoprotein(a) [Lp(a)] has been identified as an independent risk factor for coronary heart disease (CHD) events. However, few data exist on the clinical importance of Lp(a) lowering for CHD prevention. Hormone therapy with estrogen has been found to lower Lp(a) levels in women. OBJECTIVE To determine the relationships among treatment with estrogen and progestin, serum Lp(a) levels, and subsequent CHD events in postmenopausal women. DESIGN AND SETTING The Heart and Estrogen/progestin Replacement Study (HERS), a randomized, blinded, placebo-controlled secondary prevention trial conducted from January 1993 through July 1998 with a mean follow-up of 4.1 years at 20 centers. PARTICIPANTS A total of 2763 postmenopausal women younger than 80 years with coronary artery disease and an intact uterus. Mean age was 66.7 years. INTERVENTION Participants were randomly assigned to receive either conjugated equine estrogens, 0.625 mg, plus medroxyprogesterone acetate, 2.5 mg, in 1 tablet daily (n = 1380), or identical placebo (n = 1383). MAIN OUTCOME MEASURES Lipoprotein(a) levels and CHD events (nonfatal myocardial infarction and CHD death). RESULTS Increased baseline Lp(a) levels were associated with subsequent CHD events among women in the placebo arm. After multivariate adjustment, women in the second, third, and fourth quartiles of baseline Lp(a) level had relative hazards (RHs) (compared with the first quartile) of 1.01 (95% confidence interval [CI], 0.64-1.59), 1.31 (95% CI, 0.85-2.04), and 1.54 (95% CI, 0.99-2.39), respectively, compared with women in the lowest quartile (P for trend = .03). Treatment with estrogen and progestin reduced mean (SD) Lp(a) levels significantly (–5.8 [15] mg/dL) (−0.20 [0.53] µmol/L)compared with placebo (0.3 [17] mg/dL) (0.01 [0.60] µmol/L) (P