Hormone replacement therapy and endothelial function: Results of a randomized controlled trial in healthy postmenopausal women

Objective: To compare the effects of 3 months treatment with tibolone (a single entity synthetic steroid hormone with estrogenic, progestanic and androgenic activities), or continuous combined conjugated equine estrogens (CEE) plus medroxyprogesterone acetate (MPA), with placebo, on endothelial function. Design: A single center, randomized, double-blind, placebo-controlled study. Setting: Research center as part of the University Medical Center Utrecht. Subjects: One hundred and five healthy postmenopausal women, sampled from the general population. Interventions: Three months treatment with tibolone or CEE+MPA or placebo. Main outcome measure: At baseline and after 3 months, endothelial function was assessed non-invasively by measuring percent lumen diameter change in the brachial artery after reactive hyperemia and sublingual nitroglycerine spray. Results: Results are presented as mean differences between treatment groups of endothelium dependent flow mediated dilatation (fmd) and endothelium independent nitroglycerine induced dilatation with 95% confidence intervals (95% CI). After treatment, there was a significant difference in mean fmd between the CEE+MPA group and the placebo group of 2.5% (95% CI: 0.3–4.6) while the tibolone group and the placebo group did not differ significantly (0.6%; 95% CI: 1.6–2.8). Nitroglycerine induced dilatation did not differ significantly between the groups. Conclusions: Hormone replacement therapy with CEE+MPA for 3 months increases endothelium dependent fmd of the brachial artery in healthy postmenopausal women. Tibolone did not alter fmd. The clinical significance of this improvement in fmd for cardiovascular disease risk needs to be established.