Estrogen replacement reverses endothelial dysfunction in postmenopausal women

Dydrogesterone does not reverse the effects of estradiol on endothelium-dependant vasodilation in postmenopausal women: a randomised clinical trial

OBJECTIVES

The purpose of this study was to evaluate endothelium-dependent flow-mediated dilation (FMD) in the brachial artery and the plasma levels of endothelin-1 in postmenopausal women at risk for coronary artery disease before and after treatment with both estradiol and estradiol plus dydrogesterone.

METHODS

Sixteen postmenopausal women (PMW) (mean age 58+/-9 years) with more than two risk factors for coronary artery disease, were randomized to receive either oral estradiol (2 mg) for 28 days or oral estradiol (2 mg) for 14 days and oral estradiol (2 mg) and dydrogesterone (10 mg) for 14 days, in a double-blind, placebo-controlled, single cross-over study. Patients were crossed-over the complementary treatment 7 days after completing the first treatment. The study of forearm blood flow and the measurement of plasma endothelin-1 levels was carried out before and after each treatment.

RESULTS

Estradiol significantly increased FMD as compared to baseline; the addition of dydrogesterone did not affect the effect of estradiol on FMD. Similarly reactive hyperemic flow increased after estradiol alone or in association with dydrogesterone compared to baseline. Plasma levels of endothelin-1 were significantly reduced by estradiol both when administered alone or in association with dydrogesterone.

CONCLUSIONS

Hormone replacement therapy with estradiol and dydrogesterone improves endothelial function and reduces plasma levels of endothelin-1 in PMW at risk for coronary artery disease.

A study of hormone replacement therapy in postmenopausal women with ischaemic heart disease: the Papworth HRT Atherosclerosis Study

OBJECTIVE

To assess the possible benefit of hormone replacement therapy (HRT) in the secondary prevention of ischaemic heart disease.

DESIGN

A prospective randomised trial of transdermal HRT in women with definite ischaemic heart disease.

SETTING

A regional cardiac unit.

POPULATION

Postmenopausal women with angiographically proven ischaemic heart disease.

METHODS

A total of 255 postmenopausal women with angiographically proven ischaemic heart disease were recruited and randomised; 134 were treated with transdermal HRT and 121 acted as controls. The women were seen at six monthly intervals. The primary end points, which were determined by a blinded assessor, were admission to hospital with unstable angina, proven myocardial infarction or cardiac death. A total of 53 (40%) patients withdrew from the HRT group and eight (7%) from the control group. The mean duration of follow up was 30.8 months.

MAIN OUTCOME MEASURES

Admission to hospital with unstable angina, proven myocardial infarction or cardiac death.

RESULTS

During follow up, there were 53 primary end-point events in the HRT group and 37 in the control group. Using an intention-to-treat analysis, the primary end-point event rate was 15.4 events per 100 patient years for the HRT group compared with 11.9 for the control group (event rate ratio 1.29 (95% CI 0.84-1.95, P = 0.24)). Using a per-protocol analysis, there was an event rate ratio of 1.49 (0.93-2.36, P = 0.11) for the HRT arm compared with the control arm. Particularly during the first two years of follow up, the HRT group had a higher, but not statistically significant, event rate than the control group.

CONCLUSION

Our findings suggest that transdermal HRT should not be commenced for the purpose of secondary prevention in postmenopausal women with angiographically proven ischaemic heart disease.

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.

The effects of hormone replacement therapy on endothelial function in women with Turner's syndrome

OBJECTIVES

To examine the effect of hormone replacement therapy (HRT) on endothelial function of forearm resistance vessels in women with Turner's syndrome.

DESIGN

Subjects were studied on three occasions: on their usual HRT (study 1), then after 6 weeks off HRT (study 2) and finally after a further 6 weeks on HRT (study 3).

PATIENTS

Seven young women with Turner's syndrome were studied.

MEASUREMENTS

Forearm blood flow in response to intrabrachial infusion of bradykinin, 10, 30, 100 pmol/min (endothelium-dependent vasodilator), glyceryl trinitrate, 4, 8, 16 nmol/min (GTN; endothelium-independent vasodilator), noradrenaline, 60, 120, 240 pmol/min (NA, alpha-adrenergic receptor agonist) and NG-monomethyl-l-arginine, 1, 2, 4 micromol/min (L-NMMA; NO synthase inhibitor) was assessed by bilateral venous plethysmography.

RESULTS

The vasodilator response to bradykinin, expressed as the within-subject mean difference in area under the dose-response curve between study 2 and study 1, was significantly diminished (-744.2 +/- 287.2, P = 0.04) but improved 6 weeks after HRT recommencement. However, there was no significant change in response to GTN (between study 2 and study 1, 189.5 +/- 247.8, P = 0.47). The vasoconstrictor response to L-NMMA was also diminished in study 2 when compared to study 1 (-100.4 +/- 35.4, P = 0.039) and was restored after HRT was recommenced (between study 3 and study 2, 117.5 +/- 69.3, P = 0.17) whereas there was no significant difference in response to NA between study 2 and study 1 (76.7 +/- 50.6, P = 0.18) or study 3 and study 2 (-70.8 +/- 71.1, P = 0.38).

CONCLUSIONS

HRT improves endothelial function in women with Turner's syndrome.

Sex hormone replacement therapy reverses altered venous contractility in rats after pharmacological ovariectomy

OBJECTIVE

Female sex hormones have several important effects on the venous system. We earlier found that hormone replacement has a significant effect on venous distensibility, but effects of menopause and hormone replacement on venous contractility have never been studied. Therefore, and because the changes we found earlier in distensibility were most likely caused by alterations of contractility, we examined the changes in contractility of saphenous vein caused by depletion and replacement of sex hormones in female rats.

DESIGN

Twenty Sprague-Dawley rats were pharmacologically ovariectomized by triptorelin. Ten of these rats received combined sex hormone replacement (HRT) with estradiol propionate and medroxyprogesterone acetate. The rest were given vehicle. Ten animals without ovariectomy served as controls. After 3 months of treatment, segments of the saphenous vein were dissected. Pressure-diameter curves were recorded in relaxed, contracted, and control states.

RESULTS

Venous diameter, adjusted for body weight, was significantly decreased after pharmacological ovariectomy. HRT increased the diameter. The presence of sex hormones augmented norepinephrine contraction measured at physiological pressures (control: 19.2 +/- 2.3%; pharmacological ovariectomy: 15.2 +/- 1.4%, p < 0.05 and 17.8 +/- 2.2% following HRT). Myogenic (spontaneous) tone of the saphenous vein did not change after ovariectomy, but it was lowered by hormone replacement (control: 8 +/- 1.1%; ovariectomy: 6.9 +/- 2.5%; ovariectomy + HRT: 2.7 +/- 1.1%, p < 0.05).

CONCLUSIONS

Sex hormone depletion induces significant alterations in contractility of the saphenous vein, which could perturb venous capacitance function and distensibility. This effect has a potential role in the development of hypertension and venous varicosity, and these changes could possibly be prevented by HRT.

Arterial stiffness is not improved in long-term use of estrogen

OBJECTIVE

The purpose of this study was to compare arterial stiffness in long-term users of estrogen who were postmenopausal, age-matched women who did not use estrogen, and women of fertile age.

STUDY DESIGN

In this clinical cross-sectional study, carotid, femoral, and aortic stiffness (estimated as elastic modulus and stiffness beta index) were assessed by ultrasonic phase-locked echo-tracking in 17 women who were postmenopausal and who were treated with 17 beta-estradiol implants (mean age, 68.8 years; mean duration of treatment, 20 years), 17 age-matched (+/-1 year) untreated women, and 20 women in the fertile age period.

RESULTS

Compared with women of fertile age, both postmenopausal groups had significantly higher stiffness elastic modulus and stiffness beta index (carotid, P <.001; femoral, P <.05; aorta, P <.001). However, for all 3 arteries, both stiffness indices were similar in estrogen users and nonusers and did not differ significantly. These results remained after an adjustment for systolic blood pressure, body mass index, and low-density lipoprotein cholesterol levels.

CONCLUSION

These data indicate that the arterial stiffening that is related to aging/menopause is not substantially affected by long-term estrogen therapy.

Effect of estradiol valerate alone or in association with cyproterone acetate upon vascular function of postmenopausal women at increased risk for cardiovascular disease

OBJECTIVES

a large body of evidence has been accumulated suggesting that impairment of vascular endothelial function is an initial step in the development of atherosclerosis. Recent studies have shown that estrogen replacement therapy in postmenopausal women (PMW) improves endothelium-dependent, flow-mediated dilatation (FMD) while the cyclical adjunct of a progestin may reverse this effect.

METHODS

the purpose of this study was to evaluate endothelium-dependent, FMD in the brachial artery and the plasma levels of Endothelin-1 in menopausal females treated with estradiol valerate with and without cyclical cyproterone acetate in 20 PMW (mean age 64+/-6 years) with more than one risk factor for coronary artery disease. After a baseline evaluation, PMW entered a double-blinded, placebo controlled single cross-over study and were randomized to receive either estradiol valerate (2 mg) for 21 days or estradiol valerate (2 mg) for 11 days and estradiol valerate (2 mg) and cyproterone acetate (1 mg) for 10 days. Patients were crossed-over the complementary treatment 7 days after completing the first treatment phase. The study of forearm blood flow was repeated at the end of each treatment period.

RESULTS

estradiol valerate significantly increased FMD as compared with baseline (12+/-3 vs. 7+/-4%, P<0.01) the adjunct of cyproterone acetate did not affect the effect of estradiol valerate upon FMD (12+/-3 vs. 11+/-4%, P=NS). Similarly reactive hyperemic flow increased after estradiol valerate alone (24%) or in association with cyproterone acetate (24%) compared with baseline. Plasma levels of Endothelin-1 were significantly reduced by estradiol valerate alone or in association with cyproterone acetate.

CONCLUSIONS

in conclusion hormone replacement therapy with estradiol valerate and cyproterone acetate improves endothelial function and reduces plasma levels of Endothelin-1 in PMW at risk of coronary artery disease. These effects may be relevant for cardioprotection.

Estrogen replacement and brachial artery flow-mediated vasodilation in older women

It remains unclear whether estrogen therapy (with or without progestin) improves endothelial function in older postmenopausal women with or at risk for coronary heart disease. To address this issue, we analyzed brachial artery flow-mediated vasodilation in the Cardiovascular Health Study, a longitudinal study of cardiovascular risk factors in subjects over 65 years of age. At the tenth annual Cardiovascular Health Study examination, 1662 women returned for follow-up. Eighteen percent (n=291) were current users of estrogen replacement, most of whom (75.9%, n=221) took unopposed estrogen. Brachial artery ultrasound examinations measuring vasodilation in response to a flow stimulus (hyperemia) were performed on 1636 women. There were no statistical differences in brachial flow-mediated vasodilator responses between users and nonusers, even after adjustment for potential confounders. Absence of an effect was most notable in women over 80 years old and in those with established cardiovascular disease. However, among women without clinical or subclinical cardiovascular disease or its risk factors, there was a significant association between hormone replacement therapy use and flow-mediated vasodilator responses (P=0.01). Among older postmenopausal women, favorable vascular effects of estrogen may be limited to those who have not yet developed atherosclerotic vascular disease. These data emphasize the importance of ongoing efforts to determine the role of hormone replacement therapy for primary prevention of cardiovascular disease.

Effect of estrogen on endothelial dysfunction in postmenopausal women with diabetes

BACKGROUND

Treatment with estrogen causes increased release of nitric oxide and this appears to be an important mechanism involved in the cardioprotective effect of estrogen. Previous studies have clearly shown that estrogen has an acute vasodilatory effect. Recently, abnormality of flow mediated endothelial dilation, which is defined as an endothelial dysfunction, has been proposed as an early manifestation of atherogenesis. However, its effect in type 2 diabetes is unknown. Stimulus-provoked endothelium dependent dilatation, using high-resolution external vascular ultrasound, is a useful method in the measurement of endothelial function. The main advantages of this method are that it is completely non-invasive, accurate and reproducible. This classical method for the measurement of endothelial dysfunction, utilizing non-invasive, high-resolution ultrasonography, has some limitations especially in terms of reproducibility. To improve the accuracy and reproducibility of this method, measurements made for this study involved the use of an additional attachment. This device was an ultrasound probe that was attached to the arm of patient. In addition, this study evaluated not only a change in diameter in terms of flow mediated vasodilation, but also initial and peak response times during this test. The aims of this study are: (1) to evaluate the flow mediated peak vasoreactivity (FMD), the lag time from base line to initiation of vasodilation (IRT) and the peak response of endothelial dependent vasodilation in a control group and in young diabetic patients; and (2) to evaluate the effect of estrogen treatment on flow mediated vasodilation in postmenopausal women with diabetes.

METHOD

Measurements were taken for flow mediated vasodilation (endothelial dependent vasodilation: FMD), endothelial independent vasodilation (EID) and lag time from base line to initial reaction of FMD. The aforementioned non-invasive method and attachment were used. Subjects for the experiment were 12 young people with diabetes (six male and six female, mean age 26.3) and 12 age-matched healthy controls (six male and six female, mean age 25.6). In addition, measurements were taken for FMD, EID and lag time in the brachial artery before and after estrogen supplementation (Premarin 0.625 mg for 7 days). Subjects for the experiment were 16 normal postmenopausal women and 18 age-matched postmenopausal women with type 2 diabetes.

RESULT

There is no significant difference in BMI (body mass index), mean age, or blood pressure between the control group and the young diabetic group. There were no differences in age, total and LDL cholesterol levels or body mass index between the groups of postmenopausal women (P<0.05). However, the HDL cholesterol level was found to be significantly lower in postmenopausal women with diabetes than in normal postmenopausal women (respectively, a mean+/-SD; 38.95+/-11.96 mg/dl vs. 52.20+/-9.55 mg/dl, P<0.05). The FMD of young diabetic patients is slightly lower than that of age-matched young healthy controls (healthy control: 8.9+/-2.7%, young diabetic patients: 6.3+/-2.1%, P<0.05). There was no difference in endothelial independent vasodilation between the control group and the young diabetic group. The IRT of FMD was significantly shorter in the healthy control group than in the young diabetic group (healthy control: 20.4+/-2.8 s, diabetic group: 29.5+/-5.4 s, P<0.0001). In contrast, the IRT of EID was no different between the two groups. The IRT of FMD showed a significant negative correlation with FMD (r=-0.61, P<0.01) and a significant negative correlation with high-density lipoprotein (HDL) cholesterol (r=-0.68, P<0.0001). The basal endothelium dependent vascular reactivity was significantly decreased in postmenopausal women with diabetes compared with normal postmenopausal women (8.0+/-3.9 vs. 13.7+/-6.2%, P<0.05). Estrogen supplementation increased endothelium dependent vasodilation not only in postmenopausal women with diabetes (from 8.0+/-3.9 to 15.1+/-4.0%, P<0.05) but also in normal postmenopausal women (from 13.7+/-6.2 to 20.1+/-4.7%, P<0.05). In contrast, the responses to sublingual nitroglycerin were comparable between postmenopausal women with diabetes (from 21.1+/-6.0 to 22.1+/-4.1%, P>0.05) and normal postmenopausal women (from 25.8+/-7.8 to 25.2+/-4.5%, P>0.05), both before and after estrogen supplementation.

CONCLUSION

These findings indicate that in addition to the percentage change in FMD, lag time from base line to initial response time (IRT) of FMD is a good indicator for evaluation of endothelial dysfunction. Also, this new parameter may be a more sensitive parameter for differentiation between the diseased state and the normal state of the endothelium than percentage changes in FMD. In terms of postmenopausal women, endothelial dysfunction was prominent in women with diabetes and was significantly improved by estrogen but not reversed. These results suggest that other factors in addition to estrogen deficiency play a role in endothelial dysfunction in postmenopausal women with diabetes mellitus.

Effects of raloxifene and hormone replacement therapy on markers of serum atherogenicity in healthy postmenopausal women

OBJECTIVE

To determine the effect of raloxifene (RLX) and hormone replacement therapy (HRT) on non-high density lipoprotein cholesterol (non-HDL-C) levels and the apolipoprotein-B/apolipoprotein-A1 (apo-B/apo-A1) concentration ratio, markers of serum atherogenicity, in postmenopausal women.

METHODS

Three hundred and ninety healthy postmenopausal women aged 45-72 years were enrolled in a double-blind, randomized, placebo-controlled, parallel trial at eight outpatient sites in the United States. Women were randomly assigned to receive continuous combined HRT (0.625 mg/day conjugated equine estrogen and 2.5 mg/day medroxyprogesterone acetate), 60 or 120 mg/day raloxifene, or placebo for 6 months. Serum concentrations of non-HDL cholesterol and the apo-B/apo-A1 concentration ratio were measured in serum samples obtained at baseline and at 6 months of treatment.

RESULTS

At 6 months, non-HDL-C and apo-B/apo-A1 were significantly reduced by 60 mg/day RLX (10 and 11%, respectively), 120 mg/day RLX (9 and 12%, respectively) and HRT (10 and 12%, respectively), compared with placebo. The effect of all treatments to lower non-HDL-C and apo-B/apo-A1 was greatest in women with hypercholesterolemia (total-C>240 mg/dl) at baseline. Among women with undesirable (>160 mg/dl) non-HDL cholesterol at baseline, RLX and HRT lowered the percentage of these women remaining above this threshold after 6 months (placebo, 89%; 60 mg/day RLX, 61%; 120 mg/day RLX, 74%; HRT, 58%). Similar results were observed for women with high (>190 mg/dl) non-HDL cholesterol at baseline.

CONCLUSION

In healthy postmenopausal women, RLX and HRT lower serum non-HDL-C and apo-B/apo-A1, indicators of serum atherogenicity, to a similar extent.

The use of hormone replacement therapy in postmenopausal women with type 2 diabetes

In healthy postmenopausal women, estrogen or hormone replacement therapy (ERT or HRT) can alleviate menopausal symptoms and prevent osteoporosis and may also protect against cardiovascular disease (CVD). In addition to improving lipid metabolism, there are reports that estrogen also improves parameters regulating carbohydrate metabolism, including insulin resistance, in healthy women. Therefore, it is likely that ERT or HRT would also benefit women with type 2 diabetes, not only in relieving menopausal symptoms but also in improving the metabolic abnormalities associated with diabetes and in preventing cardiovascular disease.

Preserved forearm endothelial responses with acute exposure to progesterone: A randomized cross-over trial of 17-beta estradiol, progesterone, and 17-beta estradiol with progesterone in healthy menopausal women

Regularly menstruating women are relatively protected from cardiovascular disease. Epidemiological and endothelial function studies attribute this protection to estradiol (E(2)), but both progesterone (P) and E(2) are normally present. A range of vascular effects of added progestins have been described, from neutral to detrimental, but the effects of P per se on endothelial function in humans have not been reported. We therefore investigated the acute effects of E(2), P, and E(2) combined with P, on endothelium-dependent and -independent forearm blood flow responses. Using venous occlusion plethysmography, forearm blood flow (FBF) was measured during acute brachial artery infusions, achieving physiologic levels of 17-beta-E(2), P, and 17-beta-E(2) with P in healthy menopausal women with no cardiovascular disease risk factors. Vehicle or hormones were infused, in random order, on 4 days, 1 week apart. Flow responses were measured during coinfusions of hormone with the endothelium-dependent vasodilator acetylcholine and the endothelium-independent vasodilator sodium nitroprusside. Twenty-seven healthy menopausal women were studied, and all had normal baseline endothelial responses. Small ( approximately 15%), statistically nonsignificant increases in endothelium-dependent flow responses were seen after all acute hormone treatments. No impairment in response was seen with P alone or in combination with 17-beta-E(2). In healthy menopausal women without cardiovascular disease risk factors and without baseline defects in endothelial function, acute exposure to physiologic levels of 17-beta-E(2), P, and 17-beta-E(2) with P produced equivalent endothelium-dependent responses. These data suggest that P does not have detrimental vascular effects in humans.

Effect of estrogen replacement therapy on insulin sensitivity of glucose metabolism and preresistance and resistance vessel function in healthy postmenopausal women

In the present study, we hypothesized that estradiol, via its ability to vasodilate in an endothelium-dependent manner, might enhance vascular effects of insulin. Basal and insulin-stimulated peripheral blood flow and resistance, arterial stiffness, and glucose metabolism were determined in 27 healthy postmenopausal women before and after 12 weeks of treatment with either transdermal or oral estradiol or corresponding placebo preparations. Whole body insulin sensitivity was determined using the euglycemic insulin clamp technique (rate of continuous insulin infusion 1 mU/kg.min), forearm blood flow with a strain-gauge plethysmography, and arterial stiffness using pulse wave analysis. Estradiol therapy increased basal peripheral blood flow (1.5 +/- 0.1 vs. 1.9 +/- 0.1 mL/dL.min, 0 vs. 12 weeks; P: < 0.01), decreased peripheral vascular resistance (65 +/- 3 vs. 52 +/- 3 mm Hg/mL/dL.min, respectively; P: < 0.01), and diastolic blood pressure (78 +/- 2 vs. 75 +/- 2 mm Hg, respectively; P: < 0.05) but had no effect on large artery stiffness. Infusion of insulin did not acutely alter peripheral blood flow but diminished large artery stiffness significantly both before and after the 12-week period of estradiol therapy. No measure of acute insulin action (glucose metabolism, blood flow, or large artery stiffness) was altered by estradiol or placebo treatment. These data demonstrate that insulin and estradiol have distinct hemodynamic effects. Physiological doses of estradiol increase peripheral blood flow but have no effects on large artery stiffness, whereas physiological concentrations of insulin acutely decrease stiffness without changing peripheral blood flow. Putative vasculoprotection by estradiol is, thus, not mediated via alterations in arterial stiffness or insulin sensitivity.

Differential effects of oral and transdermal estrogen replacement therapy on endothelial function in postmenopausal women

BACKGROUND

We determined whether the vascular effects of estradiol depend on the route of administration by comparing the effects of oral estradiol and transdermal placebo, transdermal estradiol and oral placebo, and transdermal placebo and oral placebo on in vivo endothelial function in 27 postmenopausal women.

METHODS AND RESULTS

Endothelial function was assessed from blood flow responses to intrabrachial artery infusions of endothelium-dependent (7.5 and 15 microgram/min acetylcholine) and endothelium-independent (3 and 10 microgram/min of sodium nitroprusside) vasodilators at 0, 2, and 12 weeks. In the oral estradiol group, the increase in flow above basal during infusion of the low dose of acetylcholine at 0, 2, and 12 weeks averaged 6.0+/-0.8, 6.9+/-0.8, and 11.3+/-1.2 (P<0.01 versus 0 and 2 weeks) mL. dL(-1). min(-1) at 0, 2, and 12 weeks. The percentage increases versus 0 weeks averaged 21+/-14% at 2 and 120+/-34% at 12 weeks. During the high-dose acetylcholine infusion, the increase in flow above basal averaged 8.6+/-1.3, 10.2+/-1.5, and 15.1+/-1.8 (P<0.05 versus 0 weeks) mL. dL(-1). min(-1), respectively. The percentage increases versus 0 weeks averaged 22+/-10% at 2 weeks and 119+/-46% at 12 weeks. In the oral estradiol group, endothelium-independent vasodilatation also improved significantly, but less markedly than endothelium-dependent responses. In the transdermal and placebo groups, all vascular responses remained unchanged. Oral but not transdermal estradiol also induced significant decreases in LDL cholesterol and Lp(a) concentrations and an increase in HDL cholesterol within 2 weeks.

CONCLUSIONS

We conclude that oral but not transdermal estradiol induces potentially antiatherogenic changes in in vivo endothelium-dependent vasodilatation and lipid concentrations.

Flow-mediated dilatation

Arterial endothelial dysfunction is one of the key early events in atherogenesis, preceding structural atherosclerotic changes. It is also important in the late stages of obstructive atherosclerosis, predisposing to constriction and/or thrombosis. Endothelial function can be measured in coronary arteries and in the periphery by measuring vasomotor function after intra-arterial infusion of pharmacologic substances which enhance the release of endothelial nitric oxide. The disadvantage of these methods is their invasive nature, which generally makes them unsuitable for studies involving asymptomatic subjects. For this reason, noninvasive tests of endothelial function have been developed. In the most widely used of these, an ultrasound-based method, arterial diameter is measured in response to an increase in shear stress, which causes endothelium-dependent dilatation. Endothelial function assessed by this method correlates with invasive testing of coronary endothelial function, as well as with the severity and extent of coronary atherosclerosis. This noninvasive endothelial function testing has provided valuable insights into early atherogenesis, as well as into the potential reversibility of endothelial dysfunction by various strategies, including pharmacological agents (lipid lowering, ACE inhibition), L-arginine, antioxidants and hormones.

Postmenopausal hormone replacement improves proteinuria and impaired creatinine clearance in type 2 diabetes mellitus and hypertension

OBJECTIVE

To determine whether hormone replacement therapy can reverse established renal microvascular damage in type 2 diabetes and hypertension.

DESIGN

Prospective, single centre clinical trial.

SETTING

Outpatient clinics.

PARTICIPANTS

Sixteen diabetic and hypertensive postmenopausal women (age 47-57 years)

METHODS

Administration of a cyclic combination of oestradiol and norgestrel orally for 3.5 monthly cycles.

RESULTS

Comparing the baseline values, mean (SD) 24-hour urine protein excretion was reduced from 0.452 g (0039) to 0.370 g (0.047) (P < 0.01) and creatinine clearance was increased from 1.68 mL/sec (0.11) to 1.77 mL/sec (0.08) (P < 0.05). Fasting plasma glucose also improved from 6.92 mmol/L (0.47) to 6.51 mmol/L (0.28) (P < 0.05), as did serum total cholesterol from 7.26 mmol/L (0.28) to 6.65 mmol/L (0.14) (P < 0.05). Blood pressure did not change significantly. Univariate linear regression analysis showed no significant correlation between the individual changes in blood pressure, fasting plasma glucose or serum cholesterol and the individual changes in proteinuria or creatinine clearance.

CONCLUSIONS

This study shows that hormone replacement therapy may reduce proteinuria, and even improve creatinine clearance, in diabetic and hypertensive postmenopausal women. These effects are additive to nephroprotective therapy, and the mechanisms appear unrelated to conventional risk factors for vascular complications, such as high blood pressure, elevated plasma glucose or serum cholesterol.

Hormone replacement therapy in the prevention and treatment of atherosclerosis

As the population ages, the increasing number of women at risk for cardiovascular disease represents both a potential crisis and an opportunity in healthcare management. Although the overall death rate from cardiovascular disease in the general population is decreasing, the absolute numbers for women are increasing. A reduction in modifiable risk factors in women must be aggressively pursued by clinicians and health systems. Menopause is associated with many adverse effects on cardiovascular-disease risk factors in women. Estrogen replacement therapy has been shown to favorably influence many risk factors for cardiovascular disease. Despite this biologic plausibility and supporting evidence from epidemiologic studies, data from confirmatory clinical trials are lacking. Because of this, recommendations for hormone replacement therapy should be made on an individual basis.

Phytoestrogens do not influence lipoprotein levels or endothelial function in healthy, postmenopausal women

Plant estrogen or phytoestrogens (PE) are increasingly consumed for the purposes of menopause symptom relief and prevention of cardiovascular and other diseases. The objective of this study was to evaluate the effects of PE on plasma lipids and lipoproteins and on endothelial function. Twenty healthy, postmenopausal women, 50 to 70 years old, and with evidence of endothelial dysfunction, were treated with a soybean PE tablet of 80 mg/day of isoflavones. Endothelial function was assessed noninvasively using brachial ultrasound. A double-blind, placebo-controlled, randomized crossover design was employed. After 3 weeks stabilization on a standard fat-reduced diet, subjects received PE or placebo for 8 weeks in random order, separated by a washout period of 8 weeks. Compared with placebo, there were no significant effects of PE on blood pressure and plasma lipid or lipoprotein concentrations. Flow-mediated endothelium-dependent dilation (FMD) in response to reactive hyperemia was not significantly changed by PE ingestion (3. 3 +/- 0.7% on placebo vs 4.1 +/- 0.7% on PE, p >0.4). Variation in FMD was not correlated with change in plasma isoflavone concentration (r = -0.09, p >0.7). Glyceryl trinitrate endothelium-independent dilation was not significantly changed with PE (15.9 +/- 1.3% vs 13.7 +/- 1.2%, p >0.1). These results fail to show a significant impact of medium-term supplementation with 80 mg/day of isoflavones on lipid and lipoprotein levels or on endothelial function in healthy, postmenopausal women.

Hormone replacement therapy and cardiovascular disease

This year's work on hormone replacement therapy (HRT) and cardiovascular disease has been remarkable for the publication of the first randomised controlled trial of HRT use, the Heart Estrogen Replacement Study (HERS). The findings go against not only the trend of previous observational epidemiological studies, but also against findings in the very many studies which have previously shown and continue to show this year a beneficial effect of HRT on a large variety of cardiovascular risk factors, including endothelial function, here reviewed. The aspect of the effect of HRT on clotting variables is clearly crucial given the increased risk of venous thrombosis, and also increased number of cardiac events in the first 4 months of the HERS. Prothrombotic factors increase with age in women, and HRT alters these, particularly fibrinogen, factor VII, and PAI (less change with transdermal HRT) and antithrombin III. In normal women therefore the balance should be towards fibrinolysis rather than coagulation. Work has been presented in abstract for clarifying the effects of HRT on coagulation markers and grasping the problem of differences according to its route of administration. The full publications on this work are expected shortly. We are still awaiting evidence from randomized controlled trials of HRT in primary prevention; one is now recruited but will not report until 2005.

Screening for cardiovascular disease. Concepts, conflicts, and consensus

CVD in the United States is prevalent, costly, and disabling. Wherever in the arterial tree atherosclerosis occurs, the process appears to begin in youth, to develop under the influence of the same risk factors, and to be amenable to the same interventions. The relationship between CVD and its associated risk factors is continuous, is graded, and extends below thresholds previously defined as normal. This observation, in turn, is based on an appreciation that in our society, the gap between normal and optimal can be considerable. CVD is a multifactorial process, often related to modifiable lifestyle choices; we focus on any single risk factor to the exclusion of others puts patients in danger. Because risk factors rarely occur in isolation, risk assessment must be as multifactorial as the underlying disease process. By understanding differences between risk factors in terms of the impact of their modification on the underlying disease, targeted interventions become possible that are tailored to the likelihood of an individual patient acquiring CVD. To change the overall prevalence of an epidemic disease such as CVD, however, such a high-risk approach must be applied in concert with a population strategy that seeks to effect smaller degrees of change in the large segment of society that may be at only moderate risk but--because of their great numbers--bears most of the morbidity and mortality of CVD. Finally, despite the remarkable progress that has been made in our understanding of the pathophysiology of CVD and the effectiveness of risk factor modification, significant gaps remain between knowledge and behavior. Fewer than 50% of diabetics are even aware that they have the disease. Only a third of those whose lipid levels qualify them for treatment receive intervention of any kind, including dietary advice. Only 27% of hypertensives have their blood pressure adequately controlled. The potential impact of more vigorous screening practices in the primary care setting on the health of individuals and communities cannot be overstated.

Effect of prolonged administration of transdermal estradiol on flow-mediated endothelium-dependent and endothelium-independent vasodilation in healthy postmenopausal women

In 15 postmenopausal women with no cardiovascular risk factors, hormone replacement with transdermal estradiol (50 microg/day for 2 months) did not enhance flow-mediated endothelium-dependent vasodilation, reduce endothelium-independent vasodilation, and did not modify the pulsatility index and blood flow of the brachial artery. The present data do not support a positive effect of replacement with transdermal estradiol on vessel vasodilation in healthy, postmenopausal women.

Cardiovascular consequences of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS), a syndrome of hyperandrogenism and anovulation with numerous associated derangements, is typified by a substantially increased incidence of type 2 diabetes mellitus and coronary disease in mid-adult life. A marker of the disorder, and a potential determinant of the macroangiopathy, is insulin resistance. Thus, in addition to altered lipid metabolism, hypertension, hormonal derangements, obesity, and altered coagulation--all of which may contribute to the development of vascular disease--the insulin resistance and dysinsulinemia may underlie impaired fibrinolysis and related derangements within the vessel walls that may be modifiable by attenuation of insulin resistance and amelioration of hyperinsulinemia.

Individual and combined effects of estrogen/progestin therapy and lovastatin on lipids and flow-mediated vasodilation in postmenopausal women with coronary artery disease

OBJECTIVES

We sought to examine the individual and combined effects of estrogen/progestin therapy versus lovastatin on lipids and flow-mediated vasodilation in postmenopausal women with heart disease.

BACKGROUND

Little information is available regarding the relative benefits of estrogen replacement therapy versus reductase inhibitors and the potential utility of their combination as lipid-lowering therapy for postmenopausal women.

METHODS

We conducted a randomized, double-blind, crossover trial in 24 postmenopausal women, each of whom received the following drug regimens during three consecutive six-week treatment periods: 1) hormone replacement (oral dose of 0.625 mg/day conjugated equine estrogens and 2.5 mg/day medroxyprogesterone acetate); 2) 20 mg lovastatin/day and 3) hormone replacement plus lovastatin.

RESULTS

Total and low density lipoprotein (LDL) cholesterol were significantly lowered and high density lipoprotein (HDL) cholesterol was significantly increased by all three regimens compared with baseline (p < 0.05). Lovastatin was more effective than estrogen/progestin in reducing LDL (p < 0.001), but estrogen/progestin was slightly more effective in increasing HDL. The hormone replacement and lovastatin regimen blocked the estrogen-associated increase in triglycerides. Hormone replacement (alone and with lovastatin) resulted in increases in brachial artery flow-mediated vasodilator capacity (p = 0.01 for both regimens) and the area under the curve (p = 0.016 and p = 0.005, respectively) compared with baseline. Percent dilation was greatest after the hormone replacement regimen, whereas the area under the curve was greatest after hormone replacement plus lovastatin (69% improvement vs. baseline).

CONCLUSIONS

In postmenopausal women with coronary disease and hyperlipidemia, conjugated equine estrogen produced significant improvements in lipids and vasodilator responses despite the concurrent administration of low dose medroxyprogesterone acetate. Low dose lovastatin produced greater reductions in LDL, but less dramatic improvements in vasodilator responses. Estrogen/progestin plus lovastatin may provide additional benefits via a greater reduction in the LDL/HDL ratio and attenuation of estrogen-associated hypertriglyceridemia. More information is needed about the safety and efficacy of such combinations of hormone replacement and reductase inhibitor therapy.