Randomized trial of effects of continuous combined HRT on markers of lipids and coagulation in women with acute coronary syndromes: WHISP Pilot Study

AIMS: Randomized trials have not demonstrated coronary heart disease benefit from hormone replacement therapy (HRT). We hypothesized that low-dose HRT may avoid harm. METHODS AND RESULTS: We studied the effects of HRT on lipids and coagulation in women with acute coronary syndromes. A total of 100 post-menopausal women >55 years were enrolled between 2 and 28 days after an acute coronary syndrome and randomized to oral oestradiol-17beta 1 mg plus norethisterone acetate 0.5 mg daily, or matching placebo, and followed for up to 12 months. Levels of lipids, lipoproteins, and haemostasis markers were measured at baseline, 3, and 6 months. There were no significant differences in lipid levels between the two groups, probably due to concomitant statin use. Antithrombin and factor VII levels were significantly lower in the HRT group, whereas fibrinogen was significantly decreased in the placebo group. No evidence of increased coagulation activation was observed, nor of adverse cardiovascular outcomes [odds ratio (OR) 0.63 (95% confidence intervals 0.31-1.31)]. CONCLUSION: Low-dose HRT may give cardiovascular benefit. These findings require confirmation in a full clinical trial with evaluation of cardiovascular outcomes as the primary objective.