Cardiovascular Effects of Tibolone: A Selective Tissue Estrogenic Activity Regulator

Traditionally, it was accepted that long‐term hormone replacement therapy (HRT) has a cardiovascular beneficial effect in postmenopausal women with and without coronary artery disease (CAD). However, randomized trials in postmenopausal women have not shown any benefit in either primary or secondary prevention of cardiovascular events. Therefore, these findings have raised the question of whether traditional HRT (i.e., estrogen and progesterone) has a cardioprotective effect in women at risk for or with established CAD. Concerns about the use of conventional HRT have led to a search for alternatives. Tibolone is a synthetic compound with estrogenic, androgenic, and progestogenic properties that relieves climacteric symptoms and prevents postmenopausal bone loss. Tibolone possesses a tissue‐selective mechanism of action that differs from that of estrogen and/or progestogen. Unlike these compounds, tibolone's metabolites play a central role in its mode of action. Tibolone is widely used for HRT. However, its clinical impact on cardiovascular disease is still under study. The current review focuses on the effects of tibolone on the cardiovascular system and discusses clinical investigations with this compound in postmenopausal women.     

Estrogen in the prevention of atherosclerosis. A randomized, double-blind, placebo-controlled trial.

BACKGROUND: Although observational studies suggest that estrogen replacement therapy (ERT) reduces cardiovascular morbidity and mortality in postmenopausal women, use of unopposed ERT for prevention of coronary heart disease in healthy postmenopausal women remains untested. OBJECTIVE: To determine the effects of unopposed ERT on the progression of subclinical atherosclerosis in healthy postmenopausal women without preexisting cardiovascular disease. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: University-based clinic. PATIENTS: 222 postmenopausal women 45 years of age or older without preexisting cardiovascular disease and with low-density lipoprotein cholesterol levels of 3.37 mmol/L or greater (>/=130 mg/dL). INTERVENTION: Unopposed micronized 17beta-estradiol (1 mg/d) or placebo. All women received dietary counseling. Women received lipid-lowering medication if their low-density lipoprotein cholesterol level exceeded 4.15 mmol/L (160 mg/dL). MEASUREMENTS: The rate of change in intima-media thickness of the right distal common carotid artery far wall in computer image processed B-mode ultrasonograms obtained at baseline and every 6 months during the 2-year trial. RESULTS: In a multivariable mixed-effects model, among women who had at least one follow-up measurement of carotid intima-media thickness (n = 199), the average rate of progression of subclinical atherosclerosis was lower in those taking unopposed estradiol than in those taking placebo (-0.0017 mm/y vs. 0.0036 mm/y); the placebo-estradiol difference between average progression rates was 0.0053 mm/y (95% CI, 0.0001 to 0.0105 mm/y) (P = 0.046). Among women who did not receive lipid-lowering medication (n = 77), the placebo-estradiol difference between average rates of progression was 0.0147 mm/y (CI, 0.0055 to 0.0240) (P = 0.002). Average rates of progression did not differ between estradiol and placebo recipients who took lipid-lowering medication (n = 122) (P > 0.2). CONCLUSIONS: Overall, the average rate of progression of subclinical atherosclerosis was slower in healthy postmenopausal women taking unopposed ERT with 17beta-estradiol than in women taking placebo. Reduction in the progression of subclinical atherosclerosis was seen in women who did not take lipid-lowering medication but not in those who took these medications.     

The EWA (estrogen in women with atherosclerosis) study: a randomized study of the use of hormone replacement therapy in women with angiographically verified coronary artery disease. Characteristics of the study population. Effects on lipids and lipoproteins

OBJECTIVES: To evaluate the effects of hormone replacement therapy (HRT) on lipids and lipoproteins in postmenopausal women with coronary artery disease. SETTING: In this single-centre, controlled and randomized study taking place in a tertiary referral clinic, patients were examined at baseline, and after 3 and 12 months. All analyses were performed examiner-blind. SUBJECTS: Postmenopausal women (n = 118) with angiographically verified coronary artery disease were recruited consecutively from patients referred for investigational procedures due to coronary artery disease. INTERVENTIONS: The women were randomized to HRT, i.e. transdermal application of continuous 17-beta oestradiol with cyclic medroxyprogesterone actetate tablets every 3rd month for 14 days, or to a control group. MAIN OUTCOMES: Effects on lipids and lipoproteins. RESULTS: After 3 months of unopposed oestradiol, triglycerides decreased significantly compared to the control group (P = 0.006). Sequential administration of medroxyprogesterone caused a decrease in HDL cholesterol (P = 0.01), concomitantly with a decrease in ApoA1 lipoproteins (P = 0.007). No other changes in lipids or lipoproteins were observed. After 12 months of therapy, no significant differences were observed between the two groups in lipid or lipoprotein levels. Concomitant statin treatment did not alter the main findings. CONCLUSIONS: In postmenopausal women with established coronary artery disease in whom the majority is treated with statins, no additional effect of HRT on lipids or lipoproteins could be observed except for a transient decrease in triglycerides in the initial unopposed oestradiol phase. No deleterious effect could be observed during medroxyprogesterone administration except for a small transient decrease in HDL cholesterol and ApoA1 lipoproteins.     

Hormone replacement therapy enhances postprandial lipid metabolism in postmenopausal women.

Postmenopausal estrogen therapy reduces cardiovascular morbidity and mortality, except in women with advanced coronary disease. This beneficial effect is partly attributed to a reduction of fasting plasma total and low-density lipoprotein cholesterol (LDL-C) and an elevation of plasma high-density lipoprotein cholesterol (HDL-C) concentrations. Since postprandial lipemia seems to play a role in the pathogenesis of coronary artery disease, we evaluated the effect of hormone replacement therapy (HRT) on postprandial lipoprotein metabolism in 14 normolipemic postmenopausal women. A vitamin A fat-loading test before and after three cycles of treatment with a sequential combination of conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA) was used to label chylomicrons and chylomicron remnants with retinyl palmitate (RP), and RP clearance was assessed over an 8-hour period postprandially. Following 3 months of HRT, fasting total cholesterol and LDL-C levels were reduced 9.8% (P = .049) and 16.5% (P = .023), respectively. Fasting HDL-C levels increased 18.9% (P = .001). Fasting triglycerides (TGs) increased, but not significantly. Postprandial integrated plasma TGs did not change significantly. The integrated RP levels in whole plasma and chylomicron (Svedberg flotation units [Sf] > 1,000) and nonchylomicron (Sf < 1,000) fractions were reduced 58% (P = .043), 78% (P = .041), and 75% (P = .001), respectively, after hormonal treatment. Enhanced clearance of chylomicrons and chylomicron remnants by HRT may contribute to the protective effect of estrogens against cardiovascular disease in normolipemic postmenopausal women.     

Modulation of coronary flow velocity reserve by gender, menstrual cycle and hormone replacement therapy

OBJECTIVES

The purpose of this study was twofold: 1) to examine the relationship between menstrual cycle and coronary flow velocity reserve (CFVR) in young healthy women, and 2) to evaluate the effect of hormone replacement therapy by estrogen on CFVR in postmenopausal women, using transthoracic color Doppler echocardiography (TTCDE).

BACKGROUND

Although the incidence of cardiovascular disease is lower in women before menopause compared with men, postmenopausal women have an incidence of coronary artery disease similar to that of men of the same age. This is mainly dependent upon estrogen deficiency. However, no clinical report has yet examined the effect of estrogen on CFVR, which is one index of coronary microcirculation.

METHODS

We examined 15 male and both 15 premenopausal and 10 postmenopausal female healthy volunteers. We measured coronary flow velocity of the left anterior descending coronary artery at baseline and hyperemic conditions during adenosine triphosphate infusion by TTCDE and determined CFVR. Each premenopausal woman was studied two times (menstrual [M] and follicular [F] phases) in one menstrual cycle. Fifteen men were also studied at a time corresponding to women’s menstrual cycle. The postmenopausal women were studied before and two hours after oral administration of conjugated estrogen (CE).

RESULTS

Serum 17β-estradiol level in premenopausal women increased in the F phase and decreased to the same levels as in men, as in the M phase and as in postmenopausal women (123 ± 9 pg/ml vs. 28 ± 6 pg/ml, 25 ± 9 pg/ml and 19 ± 11 pg/ml; p < 0.0001, respectively). The CFVR increased in the F phase compared with that in the M phase (4.8 ± 0.4 vs. 3.7 ± 0.8, p < 0.0001). We found that CFVR in men remained unchanged (3.7 ± 0.6 vs. 3.8 ± 0.5). After CE administration, CFVR increased compared with baseline in postmenopausal women (4.1 ± 0.8 vs. 3.4 ± 0.8, p < 0.005).

CONCLUSIONS

In premenopausal women, CFVR determined by TTCDE varied during the menstrual cycle, and in postmenopausal women, CFVR increased after acute estrogen replacement.     

Intimal estrogen receptor (ER)beta, but not ERalpha expression, is correlated with coronary calcification and atherosclerosis in pre- and postmenopausal women

BACKGROUND: Controversy exists over the association of estrogen and cardiovascular disease. Estrogen receptors (ERs) alpha and beta are expressed in the endothelial cells and vascular smooth muscle cells (VSMCs) of many arteries, but the relative importance of ERalpha or ERbeta in mediating the vascular response to estrogens is not well defined, particularly in humans. We have shown previously that postmenopausal women receiving hormone therapy (HT) had lower mean coronary artery calcium, plaque area, and calcium-to-plaque ratio compared with untreated women. In this study, we examined coronary artery ERalpha and ERbeta expression in pre- and postmenopausal women as a function of plaque area, calcium area, calcium-to-plaque ratio, and estrogen status. METHODS: Coronary arteries were obtained at autopsy from a total of 55 women: nine premenopausal women, 13 postmenopausal women on HT and 33 untreated postmenopausal women (non-HT). Coronary calcification was quantified by contact microradiography, and atherosclerotic plaque area was measured histologically. Coronary artery cross-sections were immunostained for ERalpha and ERbeta, and the amount of receptors was estimated semiquantitatively in each arterial wall layer (intima, adventitia, and media). Double immunofluorescence was used to colocalize ERalpha and ERbeta with smooth muscle actin, a marker of VSMCs. RESULTS: ERbeta and ERalpha were expressed in all artery wall layers, but most avidly in the media (P = 0.001), and colocalized with VSMCs. ERbeta expression exceeded ERalpha expression in all wall layers (P < 0.001) and was adjacent to areas of calcium deposition. ERbeta expression in the intimal layer correlated with calcium content, plaque area, and calcium-to-plaque ratio (all P < 0.01) and tended to be greater in non-HT than in HT women (P = 0.06). ERalpha expression did not vary significantly among groups, nor did it correlate with calcium content, plaque area or calcium-to-plaque ratio. Expression of ERalpha but not ERbeta declined with age (P < 0.01) in HT women only. Age had no effect on ERalpha or ERbeta expression in non-HT or premenopausal women. CONCLUSIONS: ERbeta is the predominant ER in human coronary arteries and correlates with coronary calcification, a marker of severe atherosclerosis. Increased ERbeta expression is linked to advanced atherosclerosis and calcification independent of age or hormone status. Future pharmacogenetic studies that target this receptor are needed to confirm causality.     

Sex differences and the effects of sex hormones on hemostasis and vascular reactivity

Thrombus formation and vasospasm are involved in the initiation of acute ischemic events in the heart. Gender differences in persons with coronary artery disease and the incidence of myocardial ischemia have been clearly documented. In addition, it is well established that sex hormones influence the risk of developing coronary artery disease. Epidemiologic studies suggest that estrogen may exert a protective effect, yet the results of recently completed and ongoing prospective trials of estrogen and hormone (estrogen + progesterone) replacement suggest that these hormones can increase thrombotic events in postmenopausal women. This review focuses on sex (gender) differences in hemostasis and vascular reactivity and on the influence that sex hormones have on these physiologic systems. This review takes the novel approach of focusing on sex differences in hemostasis and vascular reactivity in healthy premenopausal women and men of a similar age. By comparing men and women in this age group, the confounding issues of age, pathology, or decline in sex hormone levels are avoided. Animal and in vitro investigations pertinent to examining potential cellular mechanism(s) of sex hormones in mediating these sex differences are discussed. We assume there is a relationship between the normal physiologic and pathologic effects of sex hormones; elucidating sex differences in normal cardiovascular function will help clarify the basis for sex differences in the incidence and manifestations of coronary heart disease and will aid in the future development of gender-specific therapies for cardiovascular disease.     

Endogenous testosterone and endothelial function in postmenopausal women

OBJECTIVE: It is well known that coronary heart disease incidence increases in women after menopause. This phenomenon was related to reduced levels of female sex hormones. Estrogen decline, however, is not the only hormonal change during the postmenopausal period and estrogen administration did not protect women from cardiovascular disease. Therefore, it is justified to explore other hormonal changes. The role of androgens is still controversial. The aim of the present study was to investigate the relationship between endogenous sex hormones and endothelial function, measuring the brachial artery flow-mediated dilation. METHODS AND RESULTS: Sixty postmenopausal women were consecutively enrolled and underwent a clinical and biochemical examination. Brachial artery flow-mediated dilation was also evaluated by ultrasound. After correction for confounding variables, testosterone was positively correlated to flow-mediated dilation (beta=0.277, P=0.03). Indeed, women in the lowest testosterone tertile had a flow-mediated dilation smaller than that in the highest tertile (P=0.02). CONCLUSIONS: This result could suggest that the development of cardiovascular disease after menopause is due not only to estrogen decline but also to androgen decline. More studies are needed to evaluate the role of androgen replacement therapy on postmenopausal women with low level of this hormone.     

Hormone replacement therapy is associated with less coronary atherosclerosis in postmenopausal women

Most observational studies indicate that hormone replacement therapy (HRT) protects women from cardiovascular disease. Two recent randomized trials, however, showed no reduction in coronary events with HRT in postmenopausal women. A randomized study evaluating subclinical atherosclerosis showed a beneficial effect of estrogen. In the current study we evaluated the association between HRT and coronary artery atherosclerosis, as quantified by coronary artery calcium score. Current users of HRT were significantly more likely to have a coronary artery calcium score less than 100 and were less likely to have a score greater than 400 than non-HRT users. After adjustment for cardiac risk factors, current use of HRT was associated with a significant reduction of coronary artery calcium score (-28; 95% confidence interval, -48 to -10). The average age of users was 59 yr, the mean duration of use was 9 yr, and the duration of HRT use was significantly associated with a reduction in coronary artery calcium. These results suggest that HRT suppresses atherosclerosis in the coronary arteries. The failure to modify the cardiovascular event rate in clinical trials could result from the adverse effect of HRT on complicated lesions. Additional mechanistic studies may help identify therapeutic strategies that could maximize a potential benefit of HRT on early atherogenesis while minimizing adverse proinflammatory and procoagulant effects on complicated plaque lesions.     

Combined hormone replacement therapy improves endothelial function in healthy postmenopausal women

OBJECTIVES: Large scale epidemiological studies suggest that hormone replacement therapy (HRT) reduces cardiovascular events in postmenopausal women. Improvement in endothelial function may contribute to this protective effect. DESIGN: In a prospective, double blind study, 61 healthy postmenopausal women were randomized to receive either oral continuous combined HRT [oestradiol 2 mg and norethisterone acetate (NETA) 1 mg per day] or placebo. Endothelial function, assessed by flow-mediated vasodilation (FMD) of the brachial artery and expression of soluble endothelial cell adhesion molecules (CAM) were determined before, after 3 and 6 months of therapy. RESULTS: The FMD was significantly improved in women on combined HRT (from 5.97% to 10.94% after 3 months and to 10.58% after 6 months; both P < 0.01 versus baseline values) and did not change in the placebo group (6.92% at baseline, 5.86% after 3 and 6.26% after 6 months). After 3 months of combined HRT, significant decreases of 24.6% for E-selectin and 13.9% for intercellular adhesion molecule-1 (ICAM-1) were observed (both P < 0.01 versus baseline values) and were sustained after 6 months of therapy, whilst no differences emerged in the placebo group. CONCLUSIONS: Oestradiol and norethisterone acetate improve endothelial function by both enhancing FMD and reducing the levels of soluble E-selectin and ICAM-1 in healthy postmenopausal women.     

Increased plasma concentrations of TGF-beta1 after hormone replacement therapy

OBJECTIVES AND DESIGN: Hormone replacement therapy (HRT) in postmenopausal women may reduce the cardiovascular risk. A dominant protective role of transforming growth factor beta (TGF-beta1) on coronary arteries has been proposed. Lp(a) lipoprotein may block the activation of latent TGF-beta1. Given this background, we examined the effects of HRT on TGF-beta1 and Lp(a) lipoprotein in 99 postmenopausal women. The women had angiographically documented coronary heart disease (CHD) and were randomized to either sequential transdermal 17beta-oestradiol for 14 weeks and then medroxyprogesterone (MPA) for 14 days (HRT) or to a control group (C). RESULTS: Serum levels of TGF-beta1 were increased in the HRT group compared with the C group after 3 months' treatment and this effect was sustained after 12 months. There was a significant reduction in Lp(a) lipoprotein serum levels after 3 months' treatment in the HRT group compared with the C group. However, after 12 months, no significant difference in changes in Lp(a) lipoprotein serum levels was detected between the two groups. CONCLUSION: The novel observation that transdermal 17beta-oestradiol in postmenopausal women increases levels of TGF-beta1 and lowers the concentration of Lp(a) lipoprotein suggests yet another possible mechanism for the cardioprotective effect of HRT. Whereas combination therapy of oestradiol and MPA preserves the beneficial effect on TGF-beta1, it reduces the unopposed oestradiol effects on Lp(a) lipoprotein.     

Estrogen and homocysteine

Cardiovascular diseases are the major causes of illness and death in women. Premenopausal women are relatively protected from coronary artery disease and atherosclerosis as compared to postmenopausal women, and this protection is attributed to the effects of the female sex hormone (estrogen). The vasculature, like the reproductive tissues, bone, liver, and brain, is now recognized as an important site of estrogen's action. Although estrogen's beneficial effects on the cardiovascular system are well described in many studies, the molecular basis of estrogen protective mechanisms are still quite vague. Both genomic mechanisms, mediated primarily through estrogen receptor alpha (ER alpha) and estrogen receptor beta (ER beta), and non-genomic mechanisms, through nitric oxide (NO), of estrogen action are controversial and do not entirely explain the effects of estrogen on vascular preservation during conditions of oxidative stress. Until recently, the atheroprotective effects of estrogen were attributed principally to its effects on serum lipid concentrations and cholesterol levels. However, two recent reports that estrogen therapy has no effect on the progression of coronary atherosclerosis in women with established disease, despite the favorable changes in LDL and cholesterol levels, leads to questions about the lipid/cholesterol mechanism of estrogen-mediated effects on atherosclerosis. Alternatively, the high level of homocysteine, found to correlate with accelerated cardiovascular disease and identified as an independent risk factor for atherosclerosis, was recently described to be diminished by estrogen. Protection against disturbed sulfhydryl metabolism and higher homocysteine level could be the missing link in understanding how exactly estrogen affects vascular cells metabolism and responses to oxidative stress. This review focuses on estrogen/homocysteine interactions and their relevance to the cardiovascular system.     

Postmenopausal hormone replacement therapy prevents central distribution of body fat after menopause

The reduction in cardiovascular risk induced by hormone replacement therapy is only partly explained by changes in serum lipids and lipoproteins. As body composition and body fat distribution in particular are independent predictors of cardiovascular disease, we investigated the effect of postmenopausal hormone therapy on body composition parameters directly measured. Sixty-two early postmenopausal women were followed up for 2 years in a prospective, randomized, placebo-controlled study. We found that combined estrogen-progestogen therapy prevented the increase in abdominal fat after menopause (P less than .05), and that this effect was independent of the effect on serum lipids and lipoproteins. The therapy reduced postmenopausal bone loss significantly (P less than .001), whereas it did not have a statistically significant influence on total body fat mass or total lean body mass. The findings of the present study suggest that some of the protective impact of postmenopausal hormone therapy on cardiovascular disease may be explained by the effect on body composition, in particular abdominal fat.     

Pulse pressure and coronary atherosclerosis progression in postmenopausal women

Pulse pressure, an index of large artery stiffness, has been associated with coronary events. However, mechanisms for this association remain unclear. In this study, we examined the relationship between pulse pressure and the progression of coronary atherosclerosis and the effects of hormone replacement therapy (HRT) on pulse pressure in postmenopausal women with angiographically confirmed coronary disease followed for 3.2 years in the Estrogen Replacement in Atherosclerosis (ERA) trial. In the ERA trial, 309 postmenopausal women (mean age 66+/-7 years) with coronary disease were randomized to estrogen, estrogen plus progestin, or placebo, and followed for 3.2 years. Ten standardized epicardial segments were measured for minimal diameter values at baseline and follow-up using quantitative coronary angiography. For this study, mixed-model analysis of covariance was used to: (1) test the association between pulse pressure and change in mean minimum diameter (MMD) adjusted for baseline MMD and (2) the effect of HRT on follow-up pulse pressure. After adjustment for potential confounders, there was a significant graded increase in progression of coronary stenosis with increasing quartiles of baseline pulse pressure (P test for trend=0.0001). The progression rate in women with the highest quartile of baseline pulse pressure was 5-fold higher than in women in the lowest quartile (P<0.01). In postmenopausal women with coronary disease, increased levels of baseline pulse pressure are associated with subsequent progression of coronary atherosclerosis in postmenopausal women. HRT had no detectable effect on pulse pressure.     

The effect of continuous combined hormone replacement therapy on arterial reactivity in postmenopausal women with established angina pectoris.

Most epidemiological studies have suggested that the administration of estrogen reduces cardiovascular risk in healthy postmenopausal women. More recently, however, in the large Heart Estrogen/progestin Replacement Study (HERS), it was unexpectedly found that in women with established cardiovascular disease, there was overall no difference in cardiovascular events between those treated with combined oestrogen/progestin hormone replacement therapy and those on placebo. The aim of this study was to examine the effect of combined hormone replacement therapy on arterial reactivity in women with existing angina pectoris. Seventy-four postmenopausal women with angina pectoris were recruited into a 16 week double-blind, placebo-controlled study of treatment with 2 mg of estradiol combined with 1 mg of norethisterone acetate daily. The median endothelium-dependent change in arterial relaxation increased from 5.00 to 7.69% in the treatment group and decreased from 5.57 to 3.64% in the controls. The median endothelium-independent change in arterial relaxation increased from 6.49 to 7.27% in the treatment group and decreased from 4.39 to 2.07% in the controls. The changes in arterial relaxation between the treatment and control groups were not statistically significant. The administration of estrogen/progestin did not significantly improve either endothelium-dependent or -independent arterial relaxation in postmenopausal women with established cardiovascular disease. We have previously shown that estrogen/progestin treatment improves endothelium dependent relaxation in healthy women. The results of our study provide one possible explanation for the clinical findings of the HERS study. In women with established cardiovascular disease, arterial relaxation does not increase significantly in response to treatment with combined hormone replacement therapy.     

Randomized, double-blind, placebo-controlled study on effects of raloxifene and hormone replacement therapy on plasma no concentrations, endothelin-1 levels, and endothelium-dependent vasodilation in postmenopausal women

The endothelium is thought to play an important role in the genesis of atherosclerosis, and several lines of evidence suggest that the effect of an intervention on endothelial function might predict its involvement in coronary disease progression and in the rate of cardiovascular events. Estrogen has direct effects on the blood vessel wall, indicating that vascular endothelium may play a key role in the cardiovascular protective effects of hormone replacement therapy (HRT). Raloxifene relaxes coronary arteries in vitro by an estrogen receptor-dependent and NO-dependent mechanism, thus suggesting that this selective estrogen receptor modulator could also have beneficial effects on endothelial function. This study compared the effects of HRT and raloxifene on NO products, endothelin-1 plasma levels, and endothelium-dependent vasodilatation in postmenopausal women. Healthy postmenopausal women (n=90) were enrolled in a double-blind, randomized, placebo-controlled, 6-month trial. Women were randomly assigned to receive continuous HRT (1 mg 17beta-estradiol combined with 0.5 mg norethisterone acetate), raloxifene (60 mg/d), or placebo for 6 months. Flow-mediated endothelium-dependent vasodilation of the brachial artery, plasma NO concentrations, and endothelin levels were measured at baseline and after 6 months of therapy. The mean baseline level of NO breakdown products was 26.5+/-10.7 micromol/L and increased to 36.3+/-11.4 micromol/L after 6 months of treatment with raloxifene. The mean baseline plasma endothelin level was 17.3+/-8.9 pg/mL and decreased to 11.5+/-2.1 pg/mL after 6 months of treatment with the selective estrogen receptor modulator. The mean baseline ratio of NO (breakdown products) to endothelin was also significantly increased at the end of treatment with raloxifene. Postmenopausal women treated with HRT had similar changes in plasma nitrites/nitrates and endothelin levels as well as in the ratio of NO to endothelin. In contrast, these markers of endothelial function did not change in the placebo-treated women. Flow-mediated endothelium-dependent vasodilation of the brachial artery was 8.3+/-2.1% at baseline and increased to 12.3+/-2.1% after 6 months of treatment with raloxifene. HRT also caused a significant and similar increase in flow-mediated endothelium-dependent vasodilation. No change in flow-mediated vasodilation was observed in the participants treated with placebo. We conclude that raloxifene therapy and HRT influence endothelial function and improve flow-mediated endothelium-dependent vasodilation to a comparable extent in healthy postmenopausal women at least after a 6-month treatment period. However, further investigation is warranted to enhance our understanding of the mechanisms of the effect of raloxifene on vascular function and to determine whether its effect on endothelial function may contribute to the reduction in cardiovascular-related morbidity and mortality.     

Usefulness of baseline lipids and C-reactive protein in women receiving menopausal hormone therapy as predictors of treatment-related coronary events

Blood lipids and high-sensitivity C-reactive protein (hs-CRP) are altered by hormone therapy. The goal of the present study was to determine whether lipids and hs-CRP have predictive value for hormone therapy benefit or risk for coronary heart disease events in postmenopausal women without previous cardiovascular disease. A nested case-control study was performed in the Women's Health Initiative hormone trials. Baseline lipids and hs-CRP were obtained from 271 incident patients with coronary heart disease (cases) and 707 controls. In a combined trial analysis, favorable lipid status at baseline tended to predict better coronary heart disease outcomes when using conjugated equine estrogen (CEE) with or without medroxyprogesterone acetate (MPA). Women with a low-density lipoprotein (LDL)/high-density lipoprotein (HDL) cholesterol ratio <2.5 had no increase in risk of coronary heart disease when using CEE with or without MPA (odds ratio 0.60, 95% confidence interval 0.34 to 1.06), whereas women with an LDL/HDL cholesterol ratio > or =2.5 had increased risk of coronary heart disease (odds ratio 1.73, 95% confidence interval 1.18 to 2.53, p for interaction = 0.02). Low hs-CRP added marginally to the value of LDL/HDL ratio <2.5 when predicting coronary heart disease benefit on hormone therapy. In conclusion, postmenopausal women with undesirable lipid levels had excess coronary heart disease risk when using CEE with or without MPA. However, women with favorable lipid levels, especially LDL/HDL cholesterol ratio <2.5, did not have increased risk of coronary heart disease with CEE with or without MPA irrespective of hs-CRP.     

Isoflavone supplementation and endothelial function in menopausal women

OBJECTIVE: Despite strong observational evidence for a beneficial role of oestrogen in cardiovascular disease, recent trial results suggest that hormone replacement therapy (HRT) may have adverse effects in menopausal women with established coronary heart disease. Isoflavones are oestrogen analogues found in plants with oestrogen-like properties and, because of a favourable side-effect profile, may be ideal alternatives to HRT with respect to cardiovascular benefits. Endothelial function is a marker of cardiovascular health. We aimed to determine the effect of isoflavones on endothelial function using the brachial artery reactivity test. DESIGN AND MEASUREMENTS: Twenty-nine healthy menopausal women underwent entry and exit brachial artery reactivity testing following randomization to 2 weeks of an oral soy isoflavone concentrate containing 80 mg of soy isoflavones (Archer Daniel Midland Inc., IL, USA) or placebo. RESULTS: At study exit, there was no difference between placebo and isoflavone groups with respect to flow-mediated dilation (%FMD(max)), change (entry to exit) in %FMD(max) or response to nitroglycerine (%TNG). Subgroup analyses assessing lipid and oestrogen effects did not produce any significant results. CONCLUSIONS: These results suggest that short-term oral isoflavone supplements do not improve endothelial function in healthy menopausal women.     

Prevention of cardiovascular events in early menopause: a possible role for hormone replacement therapy

Heart disease is a major cause of illness and death in women. It is well known that there is an increase in cardiovascular disease and cardiovascular risk factors after the menopause, but it is still unclear whether the change in risk factors after the menopause is only related to the aging process or is principally due to estrogen deprivation. Observational studies suggest a protective role for estrogens, whereas recent randomized controlled trials report a negative effect of oral estrogens on primary and secondary prevention of cardiovascular events. The role of inflammation in the process of atherogenesis and in determining the cardiovascular disease risk in postmenopausal women has been focused only recently as well as the role of the estrogen receptor system in different tissues and the role of genetic susceptibility to adverse events during estrogen therapy. The objective of this work was to review the current understanding of the relationships between cardiovascular disease risk factors and hormonal age-related changes in postmenopausal women and particularly in early and surgical postmenopausal women, for a more appropriate evaluation of the expected effects of therapy with exogenous estrogens in a specific sample of the large population of postmenopausal women.     

Effect of gender differences and estrogen replacement therapy on vascular reactivity

The incidence of cardiovascular disease is lower in premenopausal women compared with men; following menopause, the risk of mortality from cardiovascular disease increases in females. Postischemic dilatation of the brachial artery has been used previously as an index of endothelium-mediated vasodilation. Using this index, we examined a group of premenopausal and postmenopausal women, some of whom were on estrogen replacement therapy (ERT). All subjects were normotensive (blood pressure [BP] <140/90 mm Hg) and normoglycemic (blood glucose, <100 mg/dL). Fourteen healthy women (mean age, 27 +/- 0.8 years; mean total cholesterol, 174 +/- 6.7 mg/dL) and fourteen healthy men (mean age, 26 +/- 1.4 years; mean total cholesterol, 181 +/- 7.2 mg/dL) were investigated. Nineteen postmenopausal women were also examined; 11 were on ERT (mean age, 55 +/- 2.1 years; mean total cholesterol, 213 +/- 6.6 mg/dL) and eight were not on ERT (mean age, 60 +/- 3.6 years; mean total cholesterol, 222 +/- 14.4 mg/dL). Ischemia was induced by inflating a cuff over the forearm to a pressure of 40 mm Hg above systolic for 5 minutes. Doppler ultrasonography (Acuson [Mountain View, CA] 128XP/10c ultrasonograph with a 7.5-MHz linear array transducer) was used to measure the brachial artery diameter before inflation and 15 seconds and 45 to 60 seconds following cuff deflation. Flow-mediated dilatation (FMD%) and hyperemia were defined as the percentage increase over basal diameter and basal flow, respectively. Postischemic median dilatation in men was 4.20% (interquartile range, 2.13% to 5.56%) and 11.48% (interquartile range, 8.70% to 14.29%) in age-matched premenopausal women (P < .01). For women on ERT, the postischemic median dilatation was 8.11% (interquartile range, 6.01% to 11.60%), as compared with 2.82% (interquartile range, 1.32% to 3.28%) for women without ERT (P < .01). Premenopausal women showed significantly greater dilatation after ischemia than postmenopausal women without ERT (P < .0001). Hyperemia was similar in all groups. These findings show that postischemic vasodilation of the brachial artery is greater in premenopausal women versus age-matched men; it is decreased in postmenopausal women, and ERT restores it toward normal. The pathophysiology underlying the diminution in postischemic dilatation may be relevant to atherogenesis and coronary artery disease (CAD).