Relation between estrogen replacement therapy and restenosis after percutaneous coronary interventions

Use of MHT in women with cardiovascular disease: a systematic review and meta-analysis

This systematic review assesses the effect of menopausal hormone therapy (MHT) on cardiovascular outcomes and risk factors in postmenopausal women with cardiovascular disease (CVD). The Medline, Embase and Cochrane databases were searched from inception to December 2022 for randomized controlled trials (RCTs) and observational studies using methodology from a previous Cochrane review. Quality assessment used the Cochrane risk of bias tool and Newcastle-Ottawa scale, respectively. From 5647 studies identified, 29 (23 RCTs and six observational studies) were included. Most studies were conducted in North America or Europe and investigated oral estrogens. Participants were older with varying frequency of cardiac risk factors and underlying CVD. No significant difference was observed between MHT users and controls regarding primary outcomes of non-fatal myocardial infarction, cardiovascular death or stroke. No difference in frequency of angina, heart failure and transient ischemic attacks was observed. Inconsistent effects of MHT on angiographic progression were seen and varied with glycemic status. Estradiol had a positive effect on flow-mediated dilatation. Limited studies identified differing effects of MHT on cardiac risk factors, varying with estrogen preparation. This study confirms no benefit of MHT for secondary CVD prevention, highlighting evidence limitations and the importance of shared decision-making when managing menopausal symptoms in women with CVD.

Effect of bisphosphonate use on risk of postmenopausal breast cancer: results from the randomized clinical trials of alendronate and zoledronic acid

IMPORTANCE

Studies have shown that bisphosphonates may have antitumor and antimetastatic properties. Recently, observational studies have suggested a possible protective effect of bisphosphonates on breast cancer, but the effect of bisphosphonate use on risk of breast cancer has not been tested in randomized trials.

OBJECTIVE

To assess the relationship of postmenopausal breast cancer incidence and bisphosphonate use using data from 2 randomized (1:1), double-blind, placebo-controlled trials.

DESIGN, SETTING, AND PARTICIPANTS

The Fracture Intervention Trial (FIT) randomly assigned 6459 women aged 55 to 81 years to alendronate or placebo for a mean follow-up of 3.8 years. The Health Outcomes and Reduced Incidence With Zoledronic Acid Once Yearly-Pivotal Fracture Trial (HORIZON-PFT) randomly assigned 7765 women aged 65 to 89 years to annual intravenous zoledronic acid or placebo for a mean follow-up of 2.8 years. Data were collected at clinical centers in the United States (FIT and HORIZON-PFT) and in Asia and the Pacific, Europe, North America, and South America (HORIZON-PFT). Women, in either study, with recurrent breast cancer or who reported a history of breast cancer were excluded from analyses. In each trial, a blinded review was conducted of each cancer adverse event report to verify incident invasive breast cancer cases. The primary analysis compared events in the active vs placebo group using a log-rank test.

INTERVENTION

Alendronate vs placebo (FIT) or zoledronic acid vs placebo (HORIZON-PFT).

MAIN OUTCOMES AND MEASURES

Hazard ratio for incident breast cancer in the bisphosphonate treatment group compared to the placebo group.

RESULTS

There was no significant difference in the rate of breast cancer in FIT: 1.5% (n = 46) in the placebo group and 1.8% (n = 57) in the alendronate group (hazard ratio [HR], 1.24 [95% CI, 0.84-1.83]). In HORIZON-PFT, there was also no significant difference: 0.8% (n = 29) in the placebo group and 0.9% (n = 33) in the zoledronic acid group (HR, 1.15 [95% CI, 0.70-1.89]). There was also no significant difference when the data from FIT and HORIZON-PFT were pooled (HR, 1.20 [95% CI, 0.89-1.63]).

CONCLUSIONS AND RELEVANCE

These 2 randomized clinical trials do not support the findings from observational research. Contrary to the results from observational studies, we found that 3 to 4 years of bisphosphonate treatment did not decrease the risk of invasive postmenopausal breast cancer.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00049829 (HORIZON-PFT).

Menopause, Hormone Therapy and Cardiovascular and Cerebrovascular Disease

Introduction: Cardiovascular disease is the leading cause of death and morbidity among postmenopausal women, and oestrogen deficiency may be an important factor in its development. The role of oestrogen replacement in preventing cardiovascular disease is controversial. The aim of this descriptive review is to analyse the available data and to recommend evidence-based practice guidelines pertaining to hormone therapy in the context of cardiovascular and cerebrovascular health. Materials and Methods: Relevant clinical trials were identified by computerised literature search. The collated data were presented to fellow gynaecologists for review, analysis of results and discussion in a series of meetings dedicated to finding the best evidence in menopause management. The evidence was used to formulate clinical practice guidelines for the management of women with significant cardiovascular risk factors. Results: Evidence from animal studies and observational trials supported a cardio-protective effect of postmenopausal hormone therapy. More recent randomised clinical trial data have shown no significant reduction of coronary heart disease, and have confirmed a higher incidence of stroke and venous thromboembolism. Conclusions: The evidence is widely divergent regarding postmenopausal hormone therapy and cardiovascular risk. More consistent data are available reporting an increased risk in the incidence of venous thromboembolism and stroke. It is important to be clear about the indications of hormone use and to utilise alternative modalities to promote cardiovascular health in the postmenopausal population. Key words: Cerebrovascular accident, Hormone replacement therapy, Stroke, Thromboembolism

Does Addition of Estradiol Improve the Efficacy of a Rapamycin-Eluting Stent?

OBJECTIVES

This study aimed to assess the efficacy of a rapamycin plus 17-beta-estradiol-eluting stent versus a rapamycin-eluting stent in patients with coronary artery disease.

BACKGROUND

Estradiol promotes rapid re-endothelialization of coronary stents in animal models, but it is not known whether combining this drug with rapamycin represents an improved drug-eluting stent technology in terms of reduced lumen renarrowing.

METHODS

In this randomized study, we enrolled 502 patients with de novo lesions in native coronary arteries who were randomly assigned to receive either a polymer-free, estradiol plus rapamycin-eluting stent (ERES) (n = 252) or a polymer-free, rapamycin-eluting stent (RES) (n = 250). The primary end point was in-stent late lumen loss in the follow-up angiography. Secondary end points were binary angiographic restenosis, target lesion revascularization, combined incidence of death and myocardial infarction, and incidence of stent thrombosis during 1 year after randomization. The study was designed to test for the superiority of the ERES compared with the RES with respect to in-stent late lumen loss.

RESULTS

Late lumen loss (0.52 +/- 0.58 mm vs. 0.51 +/- 0.58 mm, p = 0.83), the incidence of binary angiographic restenosis (17.6% vs. 16.9%, p = 0.85), the incidence of target lesion revascularization (14.3% vs. 13.2%, p = 0.72), the combined incidence of death and myocardial infarction (7.9% vs. 8.0%, p = 0.98), and the incidence of stent thrombosis (0.8% vs. 1.2%, p = 0.99) were not significantly different between the ERES group and the RES group.

CONCLUSIONS

No apparent beneficial effect is obtained by adding estradiol to a polymer-free rapamycin-eluting stent during the first year after the procedure. (The ISAR-PEACE trial; http://clinicaltrials.gov/ct/show/NCT00402636?order=1; NCT00402636).

Phytoestrogen derivatives differentially inhibit arterial neointimal proliferation in a mouse model

Neointimal proliferation is a key element in atherosclerotic plaque formation and in arterial restenosis following angioplasty. Estrogen-like compounds, including naturally occurring plant phytoestrogens, are known to alter the extent of neointimal proliferation. This study investigates the anti-atherogenic/restenotic effect of several synthetic metabolites of isoflavone phytoestrogens (dihydrodaidzein, tetrahydrodaidzein and dehydroequol) (Novogen, Sydney, Australia). Acute neointimal proliferation was induced in the iliac artery of cholesterol-fed mice, by mechanically damaging the endothelium. Phytoestrogens were administered orally for 4 weeks and the damaged arteries harvested. Intimal area, as a percentage of the iliac artery wall area, was measured. Dihydrodaidzein significantly halved the intimal response (intima approximately 25% of wall area; p < 0.01) compared with placebo diet-fed mice (intima approximately 50% of wall area), while tetrahydrodaidzein and dehydroequol showed no inhibitory effects. Immunohistochemistry demonstrated that alpha-actin-positive vascular smooth muscle cells were the major cell type in the proliferating neointima. A single layer of endothelium covered the thickened intima by 4 weeks. Thus, a specific phytoestrogen isoflavone compound (dihydrodaidzein) can selectively inhibit neointimal proliferation, either by inhibition of vascular smooth muscle cell migration and proliferation, and/or by enhancing endothelial proliferation and function, and inhibition of endothelial apoptosis.

Continuation of hormone replacement therapy during acute myocardial infarction after the women's health initiative study. Is it the time for change?

Hormone replacement therapy (HRT) was given for many years in order to relieve menopausal symptoms and was used for as long as symptom control was necessary. The Heart and Estrogen/Progestin Replacement Study (HERS) and Women's Health Initiative (WHI) studies showed that HRT should not be given for primary or secondary prevention of coronary heart disease (CHD). However, what about those patients during acute myocardial infarction who are already taking HRT? Is the 'don't stop don't start' rule still true? A 58-year-old white female, on HRT was admitted with acute myocardial infarction (MI). We tried to answer the above questions in light of the new information:Based on current evidence available from HERS and WHI trials, it is not advisable to initiate HRT in women with established CHD for the sole purpose of preventing first or recurring coronary events. A statement by the American Heart Association recommends that the decision to continue or stop HRT in women with CV disease should be based on established benefits and risks, taking patients preference into account. The WHI study did not change this policy in the acute phase. In most cases, we believe HRT should be continued for some period (our decision for 3 months long was arbitrary), and discontinued gradually. We believe that this should be the policy until we have a double-blind placebo-control data to revise.

Postmenopausal hormone use in women with acute coronary syndromes

BACKGROUND

Recent trials reveal no benefit and possible harm from chronic hormone replacement therapy (HRT). Less is known about intermediate-term outcomes associated with HRT use in the setting of acute coronary syndromes (ACS).

METHODS

To examine the prevalence of HRT use and relationships with intermediate-term outcomes among women with ACS, we classified as HRT users or nonusers 4029 postmenopausal women (age > 50 years or postmenopausal by case report form) randomized in the Sibrafiban versus Aspirin to Yield Maximum Protection from Ischemic Heart Events Post-Acute Coronary Syndromes (SYMPHONY) and 2nd SYMPHONY trials. Outcomes included 90-day and 1-year death and 90-day stroke, death, or myocardial infarction (MI); death, MI, or stroke; and death, MI, or severe recurrent ischemia (SRI).

RESULTS

HRT use was 13% overall and varied by region (Asia, 0%; Eastern Europe, 0.2%; Latin America, 0.8%; Western Europe, 4%; Australia/New Zealand, 12%; Canada, 14%; United States, 24%); estrogen-only regimens were most common (90%). HRT users were younger, had higher estimated creatinine clearance, more frequently were smokers and had prior revascularization, but less frequently had diabetes, prior angina, or heart failure. Unadjusted 90-day and 1-year mortality rates were lower among HRT users (hazard ratios [95% CI] 0.48 [0.23-0.98] and 0.35 [0.18-0.68], respectively) but after multivariable adjustment, were not significantly different. Ninety-day stroke and composite end points did not differ between HRT users and nonusers.

CONCLUSIONS

HRT use (predominantly estrogen-only) was low among patients with ACS but varied by region and was not associated with improved intermediate-term outcomes. These results are consistent with the absence of benefit from HRT use (combination or estrogen only) in previous studies in more stable populations.

Women's angiographic vitamin and estrogen trial: design and methods

The Women's Angiographic Vitamin and Estrogen trial was a randomized, double-blind, placebo-controlled study designed to test the efficacy of estrogen replacement and antioxidant vitamins for preventing angiographic progression of coronary artery disease. Postmenopausal women with one or more angiographically documented coronary stenoses of 15-75% at baseline were assigned in a 2 x 2 factorial randomization to active hormone replacement therapy (conjugated estrogens for women who had had a hysterectomy or conjugated estrogens with medroxyprogesterone for women with intact uteri) or placebo and to active vitamins E and C or their placebos. Seven clinical centers, five in the United States and two in Canada, randomized 423 women between July 1997 and July 1999. Quantitative coronary angiography was performed at baseline and repeated after projected mean follow-up of 3 years.

Estrogen-eluting, phosphorylcholine-coated stent implantation is associated with reduced neointimal formation but no delay in vascular repair in a porcine coronary model

Estrogen can inhibit intimal proliferation and accelerate endothelial regeneration after angioplasty. This suggests that estrogen may prevent in-stent restenosis. Unlike other therapies to prevent restenosis, estrogen may also not delay endothelial regrowth, thereby avoiding the risk of late stent thrombosis. The purpose of this work was to determine the effect of a 17beta-estradiol-eluting stent on neointimal formation in a porcine model. Each artery of six pigs was randomized to either a control, low-dose, or high-dose 17beta-estradiol-eluting stent. All animals were sacrificed at 30 days for histopathological analysis. There was a 40% reduction in intimal area in the high-dose stents compared with control stents (2.54 +/- 1.0 vs. 4.13 +/- 1.1 mm(2), for high dose vs. control, respectively; P < 0.05). There was complete endothelial regeneration at 30 days and similar inflammatory response to stenting on histopathology in all the stent groups. This is the first study to show that 17beta-estradiol-eluting stents are associated with reduced neointimal formation without affecting endothelial regeneration in the pig model of in-stent restenosis. Estrogen-coated stents may have a potential benefit in the prevention and treatment of in-stent restenosis.

Ovariectomy increases mitogens and platelet-induced proliferation of arterial smooth muscle

Experiments were designed to determine how ovariectomy modulates mitogenic factors in platelets and how these factors affect proliferation of coronary arterial smooth muscle. Platelet-derived growth factors (PDGF(AB) and PDGF(BB)), transforming growth factors (TGF-beta(1) and TGF-beta(2)), and vascular endothelial growth factor (VEGF(165)) were quantified in platelet lysates and platelet-poor plasma from adult gonadally intact and ovariectomized female pigs by ELISA. Proliferation of cultured coronary arterial smooth muscle cells (SMCs) from both groups of pigs was determined in response to autologous or heterologous platelet lysates. Platelet concentrations of PDGF(BB), but not PDGF(AB), TGF-beta(1), and TGF-beta(2), increased with ovariectomy. VEGF(165) was not detected in platelets from either group. Proliferation of SMCs from ovariectomized females was significantly greater on exposure to autologous or heterologous platelet lysates than proliferation of SMCs from intact females. These results indicate that ovariectomy increases concentrations of PDGF(BB) in platelets. Higher levels of PDGF(BB) in platelets in synergy with other platelet-derived products could contribute to increased proliferative arterial response to injury after ovariectomy.

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.

Reduction of post injury neointima formation due to 17beta-estradiol and phytoestrogen treatment is not influenced by the pure synthetic estrogen receptor antagonist ICI 182,780 in vitro

BACKGROUND

Animal and organ culture experiments have shown beneficial inhibitory estrogen effects on post injury neointima development. The purpose of this study was to investigate whether such estrogen effects are influenced by the estrogen receptor antagonist ICI 182,780. Different concentrations of 17beta-estradiol and the phytoestrogens genistein and daidzein were tested.

METHODS

Female New Zealand White rabbits were benumbed. In situ vascular injury of the thoracic and abdominal aorta was performed by a 3F Fogarty catheter. Segments of 5 mm were randomised and held in culture for 21 days. Three test series were performed: 1) control group--20 microM ICI--30 microM ICI--40 microM ICI. 2) control group--20 microM ICI--40 microM 17beta-estradiol--40 microM 17beta-estradiol + 20 microM ICI. 3) control group--20 microM ICI--40 microM daidzein--40 microM daidzein + 20 microM ICI--20 microM genistein--20 microM genistein + 20 microM ICI. After 21 days the neointima-media-ratio was evaluated.

RESULTS

1) Treatment with ICI 182,780 did not reduce neointima formation significantly (p = 0.05). 2) 40 microM 17beta-estradiol alone (p < 0.0001) and in combination with 20 microM ICI (p < 0.0001) reduced neointima formation significantly. 3) 20 microM genistein alone (p = 0.0083) and combined with 20 microM ICI (p = 0.0053) reduced neointima formation significantly. 40 microM daidzein did not have a significant (p = 0.0637) effect.

CONCLUSIONS

The estrogen receptor antagonist ICI 182,780 did not modulate the inhibitory estrogen effects on post injury neointima formation. These results do not support the idea that such effects are mediated by vascular estrogen receptors.

The choice of hormone replacement therapy or statin therapy in the treatment of hyperlipidemic postmenopausal women

Evidence based treatment of cardiovascular risk factors on outcome in women is still inconclusive given the very large numbers needed to achieve a significant difference in cardiovascular event. Although numerous studies of the effect of hormone replacement therapy (HRT) on risk factors have suggested benefit, the only data from a randomised control trial of HRT in secondary prevention was neutral. Coronary disease-primary prevention: (a) Statins: Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TEX CAPS). The only randomised controlled trial (RCT) to include women. There were fewer coronary heart disease (CHD) events in women but no difference in mortality. (b) HRT: no completed RCT-the results from Womens Health Initiative (WHI) and Women Intervention Study of Long Duration of Oestrogen in the Menopause (WISDOM) are awaited, the former likely to complete in 2004. There are numerous reports of positive observational epidemiological studies for HRT. There is little evidence for statin use in women who will probably not qualify for treatment on global CHD risk assessment, familial hypercholesterolemia and type 2 diabetes excepted. HRT is, therefore, not only appropriate for its multiple effects on lipoproteins, vascular function and insulin sensitivity but also for prevention of osteoporosis. Coronary disease-

SECONDARY PREVENTION

(a) Statins: the major measurable effect of these drugs is to reduce total and LDL cholesterol. In RCT trials, the Scandanavian Simvastatin Survival Study (4S), the Cholesterol and Recurrent Event (CARE) and Long-term Intervention with Pravastatin in Ischaemic Disease (LIPID), approximately 20% of subjects were female, in whom CHD events, but not CHD or total mortality were reduced. (b) HRT: there is data available from a single RCT of continuous combined premarin and medroxyprogesterone acetate (MPA) against placebo, The Heart Estrogen Replacement Study (HERS). A study of 2763 women and mean duration of 4.1 years. This study was neutral, with no reduction in CHD events or mortality. There were more events in the first year, and fewer in years 3-5. Other studies of HRT have been observational and positive for HRT. The effects of treatment on lipoproteins with statins, HRT and combination of statin and HRT have been investigated. In secondary prevention for hyperlipidemic women to achieve cholesterol <5, low density lipoprotein (LDL)<3 mmol/l statins will be first choice, possibly with HRT additionally for its other benefits on cardiovascular risk factors.

Gender gap in coronary artery disease: comparison of the extent, severity and risk factors in men and women aged 45-65 years

This retrospective study aimed to characterize coronary artery disease (CAD) and its risk factors among relatively young women, as compared to men in a similar age group. Confirmed cases of CAD were compared regarding their medical background, performance and outcome of coronary artery procedures, physical profile and lifestyle information. The study population included 179 women and 270 men aged 45-65 years who were hospitalized during the study period 1990-1995 in the Hadassah Medical Centers. Significantly more women presented with histories of prior myocardial infarction and a higher number of vessels occluded by 80% or more and required percutaneous transluminal coronary angioplasty for 3 or more arteries, and the women had a higher incidence of risk factors such as diabetes, hypertension and hypercholesterolemia than their male counterparts.

Prevention and treatment of coronary heart disease: who benefits?

Coronary heart disease (CHD) remains a leading cause of morbidity and mortality in the United States, despite our better understanding of the pathobiology of atherosclerosis, our knowledge of risk factors, the widespread availability of inexpensive cholesterol screening, and the availability of effective and well-tolerated cholesterol-lowering agents. Advances in these areas have created controversies regarding who should be screened and treated for primary or secondary prevention of coronary events. The advent of the statin class of lipid-lowering agents represented a major advance, because they are much more effective and better tolerated than previous agents. There is general agreement that patients with hypercholesterolemia and established CHD require treatment for secondary prevention of recurrent coronary events. Primary prevention is controversial in all patient groups except those with diabetes, because their risk of developing CHD is dramatically increased. Postmenopausal women and the elderly are undertreated, whereas young adults may be underdiagnosed and undertreated. Several ongoing trials may resolve the controversies about which patient groups will benefit from different prevention and treatment strategies.

Initiation of hormone replacement therapy after acute myocardial infarction is associated with more cardiac events during follow-up

OBJECTIVES

This study explored the association between the initiation of hormone replacement therapy (HRT) and early cardiac events (<1 year) in women with a recent myocardial infarction (MI).

BACKGROUND

Observational studies have linked postmenopausal hormone use with a reduced risk of death from heart disease. However, a recent randomized trial of HRT found no long-term benefit, primarily due to an increase in cardiac events in the first year.

METHODS

The Coumadin Aspirin Reinfarction Study (CARS) database contains information on HRT use and menopausal status for women with a recent MI. We classified the 1,857 postmenopausal women in CARS as prior/current HRT users if they took HRT before enrollment, new users if they began HRT during the study period or never users. We assessed the incidence of cardiac events (death, MI, unstable angina [UA]) during follow-up.

RESULTS

In our cohort, 28% (n = 524) used HRT at some point. Of these, 21% (n = 111) began HRT after their MI. New users had a higher incidence of death/MI/UA (41% vs. 28%, p = 0.001) during follow-up than never users, largely due to a higher incidence of UA (39% vs. 20%, p = 0.001). After adjustment, new users still had a significantly higher risk of death/MI/UA than never users during follow-up (relative risk [RR] = 1.44 [1.05-1.99]). Prior/current users had no excess risk of the composite end point after adjustment. Users of estrogen/progestin had a lower incidence of death/MI/UA during follow-up than users of estrogen only (RR = 0.56 [0.37-0.85]).

CONCLUSIONS

Postmenopausal women who initiated HRT after a recent MI had an increased risk of cardiac events largely due to excess UA during follow-up.

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.

Hormone replacement therapy: primary and secondary prevention

Researchers are far from understanding the mechanism(s) of action of hormone replacement therapy (HRT) on the cardiovascular system. Moreover, the results of clinical trials that can clarify these dilemmas will not be available for several years. As clients seek guidance in making the pivotal decision about taking HRT, it is important that practitioners understand what the current research reveals about its risks and benefits. This article addresses the role of HRT in primary and secondary prevention and includes observational research, clinical trials (completed and in progress), benefits and risks, and implications for clinical practice in counseling patients.

Hormones after menopause?

The average life span of a woman is increasing and the age of menopausal onset has not changed much. The length of time that a woman spends in the postmenopausal state is thus increasing. This potential estrogen-deficient state may have certain physiologic and metabolic consequences. The onset of menopause is an excellent time to assess a women's overall health and to evaluate the benefit/risk equation of hormone replacement therapy (HRT).

17beta-estradiol, gender independently, reduces atheroma development but not neointimal proliferation after balloon injury in the rabbit aorta

The aim of the present study was to investigate anti-proliferative and anti-atherogenic properties of 17beta-estradiol in balloon injured female and male rabbit aortae. Thirty-two female and 32 male New Zealand White rabbits where gonadectomised. Vascular injury was performed with a balloon catheter in the lower abdominal aorta. Male and female rabbits were randomised into four groups of eight animals each. Only two of four groups received a 0.5% cholesterol-enriched diet. One cholesterol-diet group and one normal-diet group received intramuscular injections of estradiol valerate (1 mg/kg body weight/week). After 28 days, the denuded part of the abdominal aorta was excised and analysed by morphometry and immunohistochemistry. Estrogen treatment did not show an inhibitory effect on neointimal proliferation in normo-cholesterolemic male or female rabbits. A gender independent inhibitory effect of 17beta-estradiol was seen on atheroma development in cholesterol-fed female and male rabbits, while plasma total cholesterol levels were significantly reduced in male rabbits only. The 17beta-estradiol treatment was associated with a significantly decreased number of luminal endothelial cells in normo and hyper-cholesterolemic female rabbits, as evaluated by immunohistochemical staining for 'von Willebrand factor'. Staining for Ki-67-positive proliferating cells after 28 days showed a statistically significant increased proliferative activity in the neointima of hyper-cholesterolemic female rabbits. The neointimal content of macrophages increased significantly in all hyper-cholesterolemic rabbits. Under 17beta-estradiol treatment, the number of macrophages was increased in female and decreased in male rabbits by tendency. Additionally, the 'classical' vascular estrogen receptor was present in both female and male rabbit aortae without statistically significant differences. In conclusion, 17beta-estradiol did not reduce post-injury neointima formation in normo-cholesterolemic rabbits. However, in hyper-cholesterolemic rabbits, 17beta-estradiol reduced atheroma development gender independently. This effect cannot be explained by lowering of plasma cholesterol levels or endothelium-mediated pathways, and requires further investigation on, for example, antioxidative, antiproliferative or estrogen receptor mediated effects.

Local delivery of 17-beta-estradiol decreases neointimal hyperplasia after coronary angioplasty in a porcine model

BACKGROUND

Neointimal hyperplasia is an important mechanism of restenosis after percutaneous transluminal coronary angioplasty (PTCA). Systemically administered estrogen is known to inhibit neointimal formation after arterial injury.

OBJECTIVES

We sought to assess the efficacy of locally delivered 17-beta-estradiol (BE) in inhibiting neointimal hyperplasia after PTCA.

METHODS

Eighteen juvenile farm pigs were studied. Coronary angioplasty was performed in all three coronary arteries of each animal. After PTCA, each coronary artery in each pig was randomized to receive either local delivery of 600 microg BE, vehicle alone or PTCA only. Twelve animals were euthanized at 28 days for morphometric analysis, and four animals were euthanized at seven days for immunohistochemical analysis of vascular smooth muscle cell (SMC) proliferative activity. Two animals died a few days after PTCA and were excluded.

RESULTS

On morphometric study, the arterial segments treated with BE demonstrated significantly less neointimal proliferation. Arteries treated with BE had reductions in several indexes of restenosis compared with arteries treated with vehicle alone or PTCA only: neointimal area (0.4+/-0.09 mm2 for BE vs. 1.14+/-0.33 mm2 for vehicle alone vs. 0.88+/-0.2 mm2 for PTCA only, p<0.05), percent neointima (12.16+/-2.57% vs. 25.46+/-4.73% vs. 23.02+/-3.97%, p<0.025), neointima/media area (0.59+/-0.14 vs. 1.75+/-0.41 vs. 1.67+/-0.43, p<0.01) and restenotic index (1.3+/-0.14 vs. 2.42+/-0.22 vs. 2.4+/-0.23, p<0.005). Immunohistochemistry showed decreased SMC proliferative activity in BE-treated arteries compared with the other two treatment groups (p<0.05).

CONCLUSIONS

Local delivery of BE significantly decreases neointimal hyperplasia after PTCA in pigs, probably by the inhibition of SMC proliferation.

Hormone replacement therapy should be administered as secondary prevention of coronary artery disease

* Coronary artery disease in women is associated temporally with the occurrence of menopause and loss of estrogen. * Consistently, epidemiologic evidence indicates a beneficial effect of HRT on the development of CAD (primary prevention). * Observational data in women with known CAD indicate improved angioplasty and mortality outcomes in women taking HRT. * The HERS was fraught with methodologic flaws that drastically hampered the ability of HRT to show benefit as secondary prevention for cardiovascular disease. Despite this, mortality benefit was suggested with long-term therapy.

Hormone replacement therapy and the risk of myocardial infarction in women with coronary risk factors

To assess the risk of myocardial infarction in users of post-menopausal hormone replacement therapy who are at high risk of coronary disease because of hypertension, diabetes mellitus, or smoking, we used data from a previously published case-control study of women 45-74 years. After adjustment for age, ethnicity, and education, the odds ratio for myocardial infarction in current users of hormone replacement therapy was 0.9 (95% confidence interval (CI) = 0.5-1.6) in women with no major coronary risk factors, 0.8 (95% CI = 0.5-1.8) in women with one risk factor, and 1.1 (95% CI = 0.5-2.2) in women with two risk factors.

Long-term (three years) effect of estrogen replacement therapy on major adverse cardiac events in postmenopausal women after intracoronary stenting

This study examined whether estrogen replacement therapy (ERT) in postmenopausal women impacts intermediate and long-term outcome after successful coronary stenting. Our findings offer evidence that ERT significantly reduces target lesion revascularization after intracoronary stenting in postmenopausal patients who are on ERT before the intervention.

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.

CME Paper: Hormone Replacement Therapy for Prevention or Treatment of Atherosclerosis in Postmenopausal Women: Promises, Controversies, and Clinical Trials

Cardiovascular disease is the leading cause of death among men and women in the U.S. and other developed societies. However, myocardial infarction and stroke are uncommon in women until their sixth decade and beyond. Clinicians have long suspected that the delay of a decade or more in cardiovascular disease expression in women relative to men is due to the protective effects of estrogen prior to menopause. Reports from population based observational studies of the favorable effects of hormone replacement therapy on cardiovascular morbidity and mortality have led to enthusiasm for widespread use of estrogen by postmenopausal women for the prevention of cardiovascular disease. In support of the antiatherogenic potential of estrogen are studies in postmenopausal women showing favorable effects on lipoprotein levels, fibrinolysis, and vascular function. However, a secondary prevention trial in postmenopausal women with coronary artery disease showed no cardiovascular benefit of hormone replacement therapy. Ongoing clinical trials and options to conventional hormone replacement therapy for cardiovascular protection will be discussed in this review. (c)2000 by CVRR, Inc.

Modification of serum lipids and cardiovascular risk by estrogenic active compounds

Cardiovascular disease is an important cause of death among women. After the menopause there is a steep elevation of low-density lipoprotein (LDL) cholesterol and lipoprotein(a) concomitantly with other risk factors, followed by a striking increase in arteriosclerotic vascular disease, compatible with a lack of estrogens as a causative factor. The benefit of hormone replacement therapy has been documented in several large studies, although rigorous randomized trials are still under way. However, cardiovascular events have been reduced by approximately 50%. In order to optimize beneficial effects and minimize side-effects, the characteristics of selective estrogenic active compounds are a major target of research. The anti-estrogens are the prototype of partial and selective estrogen functions. The components of conjugated estrogens are under investigation for their specific effects. For example, both 17 alpha-dihydroequilin sulfate and 17 alpha-dihydroequilenin sulfate seem to exert antioxidant activity without significant proliferative effects on uterine or breast tissues. This suggests a selective estrogenic activity dependent on the predominant type of estrogen receptor in the particular tissue. Equilin sulfate exerts a significantly stronger antioxidant activity than 17 beta-estradiol in vitro, and delta 8-estrone sulfate increases the lag time for low-density lipoprotein oxidation in vivo. These actions on lipoproteins may add to the quantitative changes of lipoproteins, while other effects are independent of lipoproteins. The 17 alpha-dihydroequilin sulfate and equilin sulfate improved the action of insulin in vivo. Data from rhesus monkeys treated with 17 alpha-dihydroequilenin sulfate indicate that additional mechanisms are probably responsible for the observed cardiovascular protection. Further studies need to be conducted in order to identify selective estrogen receptor modulators and assess their potential, especially in lowering cardiovascular risk.

Arthur C. Corcoran Memorial Lecture. Hormones and vasoprotection

There is a strong link between menopause and increased cardiovascular disease incidence in women, and observational studies suggest that postmenopausal hormone replacement therapy reduces cardiovascular disease risk by about half. Observational studies suffer from important limitations, however, and the only published prospective controlled trial of the effects of hormone replacement therapy on cardiovascular outcomes, the Heart Estrogen-Progestin Replacement Study (HERS), showed no net benefit of continuous estrogen plus synthetic progestin treatment in women with established coronary disease. Fundamental mechanistic studies of the cellular and molecular events by which hormones protect (or fail to protect) blood vessels from damage are needed to define the role of postmenopausal hormone replacement therapy in cardiovascular disease prevention. Most studies suggest that estrogen inhibits the neointimal response to acute injury in normal blood vessels, but this vasoprotective effect was not seen in vessels with preexisting atherosclerosis. Studies from our laboratory in the rat carotid injury model have shown that estrogen inhibits neointima formation via effects on all 3 layers of the vascular wall, including inhibition of medial smooth muscle cell migration and proliferation, stimulation of regrowth of endothelium, and inhibition of adventitial cell migration into neointima. Our laboratory is currently using transduced (lacZ) syngeneic fibroblasts as 'reporter' cells to delineate the factors that stimulate migration of adventitial cells into neointima after vascular injury and their modulation by estrogen and the other sex hormones. These fundamental studies will establish more rational strategies for therapeutic intervention in vascular diseases, including the basis for future gene therapy.

Effects of oestrogens and selective oestrogen receptor modulators on serum lipoproteins and vascular function

Epidemiological observations, clinical studies, and basic laboratory research suggest that oestrogen replacement therapy is associated with beneficial cardiovascular effects in postmenopausal women. Oestrogen has a multitude of biological effects that may account for this apparent benefit (which remain to be proven in randomized clinical trials), including favourable effects on the lipid profile, a direct effect on the vascular endothelium with increased nitric oxide bioactivity, and improved fibrinolysis. However, long-term oestrogen therapy increases the risk of breast and endometrial cancers. Raloxifene, a benzothiophene derivative that binds to the oestrogen receptor, is a selective oestrogen receptor modulator, producing oestrogen-agonistic effects in some tissues (liver, bone), and oestrogen-antagonistic effects in others (breast, uterus), and may prove to be an option for women with atherosclerosis and its associated risk factors who might benefit from oestrogen therapy. This review updates the current knowledge of the biological effects of oestrogen and selective oestrogen receptor modulators of potential cardiovascular importance in postmenopausal women.

The effect of hormone replacement therapy alone and in combination with simvastatin on plasma lipids of hypercholesterolemic postmenopausal women with coronary artery disease

OBJECTIVES

This study sought to compare hormone replacement therapy (HRT), simvastatin and their combination in the management of hypercholesterolemia in postmenopausal women with coronary artery disease (CAD).

BACKGROUND

Lipid-lowering therapy reduces mortality in hypercholesterolemic women with CAD. In postmenopausal women HRT seems to increase survival, particularly those with ischemic heart disease, and this is partly due to changes in lipid levels.

METHODS

We studied 16 postmenopausal women with CAD and fasting total cholesterol <200 mg/dl and low-density lipoprotein (LDL) cholesterol <130 mg/dl. We compared HRT (0.625 mg of conjugated estrogen and 2.5 mg of medroxyprogesterone acetate daily) with simvastatin (20 mg daily) and their combination in a randomized, crossover, placebo-controlled study. Each treatment period was 8 weeks long with a 4-week washout interval between treatments.

RESULTS

Simvastatin, HRT and their combination significantly reduced total and LDL cholesterol by 35%, 13%, and 33% and 45%, 20%, and 46%, respectively, compared to placebo (p < 0.001). However, simvastatin and the combination was superior to HRT (p < 0.001), and none of our patients had total cholesterol <180 mg/dl and LDL cholesterol <100 mg/dl on HRT alone. High-density lipoprotein cholesterol was not significantly affected by any of the active treatments, and triglycerides were lower during simvastatin therapy compared to placebo (p < 0.01). Apolipoprotein B was significantly reduced by simvastatin, alone and combined with HRT, by 39% and 35%, respectively, compared to placebo (p < 0.001). Alone and in combination with simvastatin, HRT significantly increased apolipoprotein A-I by 11% and 12%, respectively, compared to placebo (p < 0.05) and decreased lipoprotein (a) by 23% and 33%, respectively, compared to placebo (p < 0.05), whereas simvastatin had no significant effect on either of these parameters.

CONCLUSIONS

In hypercholesterolemic postmenopausal women with CAD, HRT exerts beneficial effects on plasma lipids but the levels currently recommended for secondary prevention are not achieved. Hormone replacement therapy combined with simvastatin is well tolerated and extremely effective, as the two therapies seem to be additive.

Estrogen for women at varying risk of coronary disease

Many epidemiological studies show that women who use estrogen therapy after menopause have significantly lower rates of heart disease than postmenopausal women who do not take estrogen. However, few studies have assessed the impact of estrogen use among women with a distinctly higher cardiovascular risk. Seven studies of estrogen therapy in women with established coronary heart disease (such as, coronary stenosis and prior myocardial infarction) are briefly reviewed. These studies all find fewer recurrent cardiovascular events and an improved survival in the estrogen group when compared to the non-estrogen group. Analysis of the effect of estrogen within different risk factor categories in the 16-year follow up of the Nurses' Health Study confirms that although relevant risk estimates are highly similar, the magnitude of the protective effect of estrogen is more pronounced among women with high baseline risk of disease.

Estrogen replacement therapy and outcome of coronary balloon angioplasty in postmenopausal women

Estrogen replacement therapy (ERT) in women after menopause is associated with prevention of clinical coronary artery disease. However, few studies have investigated possible benefits from ERT in postmenopausal women undergoing treatment for established coronary disease. We therefore retrospectively reviewed the clinical outcomes of 428 postmenopausal women undergoing percutaneous transluminal coronary balloon angioplasty (PTCA) to test the hypothesis that ERT has a beneficial effect in this setting. The women were divided into 2 groups based on ERT status at the time of the procedure. Estrogen users were younger (60 +/- 10 vs 68 +/- 9 years, p <0.001), more commonly had family histories of coronary heart disease (54% vs 41%, p = 0.04), had less incidence of hypertension (63% vs 76%, p = 0.02), and had slightly fewer diseased vessels per patient (1.3 +/- 0.5 vs 1.5 +/- 0.7, p = 0.03) compared with nonusers. No in-hospital deaths occurred in estrogen users compared with 5% hospital mortality in nonusers (p = 0.01). The combined outcome of death or myocardial infarction (MI) also was lower in estrogen users (4% vs 12%, p = 0.04). Of 348 women discharged after successful PTCA, 336 (97%) were able to be contacted at an average follow-up interval of 22 +/- 17 months (range 5 to 82). Estrogen users had superior event-free survival both for death as well as for death or nonfatal MI. Repeat revascularizations were similar in both groups (32% vs 24%, p = 0.15). In a Cox proportional-hazards model, nonusers had 4 times the likelihood of death after angioplasty compared with estrogen users (OR = 4.025, 95% CI = 1.3 to 13.4, p = 0.02). We conclude that estrogen replacement may offer protection against clinical coronary events in postmenopausal women who already have established coronary disease and are undergoing balloon angioplasty. The benefit was independent of age, smoking, presence of diabetes mellitus, or the number of diseased coronary vessels. However, it did not include a reduction in repeat revascularization procedures, suggesting no reduction in restenosis.

Impact of gender on coronary bypass operative mortality

BACKGROUND

In spite of many reports investigating the influence of gender on coronary artery operations, it is still uncertain whether gender is an independent risk factor for operative mortality. A major problem of previous reports has centered around the fact that men and women constitute quite different populations, thereby making direct comparisons difficult.

METHODS

The Society of Thoracic Surgeons National Cardiac Surgery Database was used to retrospectively examine 344,913 patients undergoing coronary artery bypass graft operations from 1994 through the most recent data harvest. The operative mortality of male and female patients was compared for a variety of single risk factors and combinations of risk factors. A logistic risk model was used to account for all important patient parameters so that individuals could be stratified into comparable categories allowing for direct comparisons of risk-matched male and female patients.

RESULTS

The univariate analysis showed that the 97,153 women carried a significantly higher mortality for each of the risk factors examined. The multivariate analysis and the risk model stratification showed that women had significantly higher mortality as compared to equally matched men in the low- and medium-risk part of the spectrum, but in high-risk patients, there was no difference between male and female mortality.

CONCLUSIONS

Gender is an independent predictor of operative mortality except for patients in very high-risk categories.

Estrogen replacement therapy after coronary angioplasty in women

OBJECTIVES

The purpose of this study was to assess the effects of estrogen replacement therapy on long-term outcome, including restenosis, myocardial infarction, stroke and death after a first percutaneous transluminal coronary angioplasty (PTCA) procedure, in postmenopausal women.

BACKGROUND

Observational and epidemiologic studies, basic laboratory research and clinical trials consistently suggest that estrogen replacement therapy is associated with beneficial cardiovascular effects in women. These cardioprotective actions may be particularly relevant to women with coronary artery disease, such as those who have undergone PTCA.

METHODS

This was a retrospective study that included 337 women who underwent elective PTCA between 1982 and 1994. The treatment group consisted of 137 consecutive women receiving long-term estrogen therapy at the time of elective PTCA and during follow-up. The control group comprised 200 women who were computer-matched with the estrogen group. The mean follow-up period was 65 +/- 35 months.

RESULTS

Actuarial survival was superior in the estrogen group; the 7-year survival rate was 93% for the estrogen group versus 75% for the control group (p = 0.001). The cardiovascular event rate (death, nonfatal myocardial infarction or nonfatal stroke) was significantly lower in the estrogen group at 7 years (12% vs. 35% in the control group, p = 0.001). The need for subsequent revascularization during follow-up was similar in the two groups. Multivariable analysis identified diabetes, estrogen therapy (adjusted risk ratio 0.38, 95% confidence interval 0.19 to 0.79) and left ventricular ejection fraction < 40% as independent correlates of cardiovascular death or myocardial infarction during follow-up.

CONCLUSIONS

Estrogen replacement therapy was associated with an improved long-term outcome after PTCA in postmenopausal women.

Anti-atherogenicity in women does not prevent restenosis after balloon angioplasty

To test the hypothesis that anti-atherogenicity in women exerts beneficial effects to prevent restenosis formation after coronary angioplasty, we studied 493 men (988 lesions) and 81 women (159 lesions), aged 40-60 years, who had undergone successful balloon angioplasty and had follow-up angiography, 4.9 +/- 4.1 months later. We compared the extent of restenosis between men and women, and between pre- and post-menopausal women, which was assessed by a categorical definition of restenosis (more than 50% diameter stenosis at follow-up) and by percent diameter measured immediately after angioplasty and at follow-up. Hypertension was more frequent in women and a significantly lower percentage of women smoked. In women, the levels of total cholesterol and low-density lipoprotein cholesterol were higher. The location of dilated lesions, frequency of angioplasty for lesions with chronic total occlusion, and frequency of emergency angioplasty in patients with unstable angina or acute myocardial infarction were similar in men and women. Restenosis formation, estimated by the categorical definition or percent diameter, did not differ between men and women, or between pre- and post-menopausal women. Menopausal status or sex was not an independent predictor of restenosis by multivariate analysis. Thus, the benefit of anti-atherogenicity in women does not play an important role in preventing restenosis after coronary angioplasty.