Miriam J.J. de Kleijn

Reproductive history and cardiovascular disease risk in postmenopausal women A review of the literature

Objecti6es: it is widely believed that oestrogen protects postmenopausal women from cardiovascular disease. It is unknown, however, whether reproductive history, which affects endogenous oestrogen levels during a woman’s life, also influences cardiovascular disease risk in postmenopausal women. We present an overview of the studies which investigate the relationship between reproductive history and risk for cardiovascular disease in women. Methods :w e conducted a Medline search of literature pertaining to age at menarche, age at menopause, parity and gravidity, breast-feeding, and length and regularity of the menstrual cycle in relation to cardiovascular diseases. Data extraction and synthesis were performed by comparing odds ratios and relative risks presented or calculated. Results: age at menarche was not found to influence cardiovascular disease risk, while menstrual cycle irregularity was associated with this risk. The studies pertaining to parity presented conflicting results: protection against as well as an increase in the risk of cardiovascular disease were found in parous women. Pregnancy loss appeared to be related to cardiovascular disease risk. Age at menopause proved to be the reproductive factor most clearly related to cardiovascular disease risk. Conclusions: only menstrual cycle irregularity, pregnancy losses, and age at menopause are possibly related to cardiovascular disease risk in postmenopausal women. All reproductive factors need to be studied together in order to assess reproductive history in a proper manner. Research of this kind will be essential if we are to further increase our knowledge regarding the nature of the effects of endogenous oestrogen on cardiovascular disease.

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.

Hormone replacement therapy in perimenopausal women and 2-year change of carotid intima-media thickness

OBJECTIVES To assess the 2-year effects of a combined regimen of oral 17beta-estradiol and desogestrel (17betaE-D) and a sequential combination of conjugated equine estrogens and norgestrel (CEE-N) on common carotid intima-media thickness and end-diastolic lumen diameter in comparison to placebo in perimenopausal women. METHODS The study was a single center, randomized, group-comparative, double-blind study with respect to the 17betaE-D and placebo groups and open with respect to CEE-N. After cycle 6, the blind was broken and the trial was continued as an open trial for another 18 months for the active study arms. The study included 121 perimenopausal women recruited from the general population. Common carotid intima-media thickness and end-diastolic lumen diameter were measured at baseline and cycle 24 with B-mode ultrasonography. RESULTS At cycle 24 small changes in intima-media thickness and lumen diameter were observed. Relative to placebo, changes in intima-media thickness were -0.009 mm [95% CI -0.045; 0.027] for 17betaE-D and -0.016 mm [95% CI -0.055; 0.024] for CEE-N. For end-diastolic lumen diameter the changes were -0.091 mm [95% CI -0.236; 0.055] and -0.125 mm [95% CI -0.820; 0.032] for 17betaE-D and CEE-N, respectively. CONCLUSIONS In this study among perimenopausal women a significant effect of 17betaE-D and CEE-N on common carotid intima-media thickness and lumen diameter could not be demonstrated. Although the sample size of the present trial is too limited to provide definite conclusions, the direction of the effect is in agreement with evidence from earlier studies on the effects of hormone replacement therapy in postmenopausal women.

Lipoprotein (a) is associated with endothelial function in healthy postmenopausal women

BACKGROUND Lipoprotein (a) (Lp(a)) is an independent risk factor for atherosclerotic cardiovascular disease. The atherogenic potential of Lp(a) may be by impairment of endothelial function. Objectives. We investigated the relation of Lp(a) plasma levels to endothelium dependent and independent dilatation of the brachial artery in healthy postmenopausal women. METHODS One hundred and five healthy postmenopausal women aged 52-67 years were included in the study. Endothelial function was assessed non-invasively by measuring percent lumen diameter change in the brachial artery after reactive hyperemia and sublingual nitroglycerine spray. RESULTS Flow mediated dilatation was inversely related to the plasma logLp(a) level. Mean change per unit logLp(a) increase:-2.83% (95% CI: -5.22--0.43). Elevated Lp(a) (>239 mg/l) (upper quartile) was associated with an impaired flow mediated vasodilatation (2.4%+/-1. 2) compared to Lp(a) < or =239 mg/l (5.2%+/-0.7). Adjustment for other cardiovascular risk factors did not change the magnitude of the association. Nitroglycerine-induced vasodilatation was not significantly lower in the high Lp(a) level group, compared to the group with normal levels of Lp(a) (< or =239 mg/l) (8.0+/-1.2 vs. 11.4%+/-0.8). CONCLUSION Elevated lipoprotein (a) levels are associated with an impaired endothelial function in healthy postmenopausal women, independent of conventional risk factors for cardiovascular disease. Since Lp(a) may be pathogenetically important for early vascular damage, elevated Lp(a) levels might contribute to the increased cardiovascular risk seen in postmenopausal women.

Does the beneficial effect of HRT on endothelial function depend on lipid changes

OBJECTIVES To determine whether improvement in endothelial function of the brachial artery observed in women treated with hormone replacement therapy (HRT) may be explained by changes in lipid profile or blood pressure, information was used obtained in a single-centre, randomised, double blind, placebo-controlled trial. METHODS Hundred-and-five healthy postmenopausal women, aged 50-65 years, were treated with 0.625 mg conjugated equine estrogens (CEE) combined with 2.5 mg medroxyprogesterone acetate (MPA) (CEE+MPA), 2.5 mg tibolone or placebo for 3 months. At baseline and after 3 months, endothelial function was assessed using flow-mediated dilatation (FMD) and nitro glycerine-mediated dilatation (NMD). Furthermore, lipids were measured. Multivariate linear regression analysis was applied to address the research question. RESULTS Treatment with CEE+MPA resulted in an improvement in FMD of 2.0% (95% CI: -0.1; 4.1). CEE/MPA reduced total cholesterol with 13% (95% CI: -18%; -7%), LDL-cholesterol with 23% (95% CI: -30%; -15%) and lipoprotein(a) (Lp(a)) with 14% (95% CI: -26%; -2%). The magnitude of the relation of CEE/MPA with endothelial function was attenuated to from 2.0 to 1.6% when change in Lp(a) was taken into account. Adjustments for other lipids or blood pressure did not attenuate the association. CONCLUSIONS The improvement in endothelial function in postmenopausal women treated with CEE+MPA appears to be partially mediated by change in Lp(a), and apparently not by changes in other lipids.