Beneficial effect of oestrogen on exercise-induced myocardial ischaemia in women with coronary artery disease

From cardiovascular protection to cardiovascular risk: the metamorphosis of menopausal hormone therapy

Over the last 70years, oestrogen therapy for the management of menopausal symptoms has undergone a metamorphosis from perceived cardiovascular protection to perceived cardiovascular risk. The former perception is based on the convincing evidence from the Nurses' Health Study cohorts and the epidemiological data surrounding early menopause. The latter, and later, perception is based on the disquieting results from two randomised controlled studies, the Heart and Estrogen/Progestin Replacement Study (HERS) and the Women's Health Initiative study (WHI). The reality is probably more nuanced than the conclusions presented by any of these studies. When face to face with a patient, the clinician must negotiate the appropriate decision pathway around the interaction between cardiovascular risk, cardiovascular disease, menopause, and oestrogen +/-progestogen-containing hormone therapy.

Sex differences in blood pressure regulation and hypertension: renal, hemodynamic, and hormonal mechanisms

The teleology of sex differences has been argued since at least as early as Aristotle's controversial Generation of Animals more than 300 years BC, which reflects the sex bias of the time to contemporary readers. Although the question "why are the sexes different" remains a topic of debate in the present day in metaphysics, the recent emphasis on sex comparison in research studies has led to the question "how are the sexes different" being addressed in health science through numerous observational studies in both health and disease susceptibility, including blood pressure regulation and hypertension. These efforts have resulted in better understanding of differences in males and females at the molecular level that partially explain their differences in vascular function and renal sodium handling and hence blood pressure and the consequential cardiovascular and kidney disease risks in hypertension. This review focuses on clinical studies comparing differences between men and women in blood pressure over the life span and response to dietary sodium and highlights experimental models investigating sexual dimorphism in the renin-angiotensin-aldosterone, vascular, sympathetic nervous, and immune systems, endothelin, the major renal sodium transporters/exchangers/channels, and the impact of sex hormones on these systems in blood pressure homeostasis. Understanding the mechanisms governing sex differences in blood pressure regulation could guide novel therapeutic approaches in a sex-specific manner to lower cardiovascular risks in hypertension and advance personalized medicine.

Poor Neurological Deficit Was an Independent 30-day Risk Factor in Symptomatic Carotid Stenosis after CEA with Selective Shunting

BACKGROUND

Carotid endarterectomy (CEA) prevents the occurrence of stroke in the future, although its efficacy depends on the detection and control of high perioperative risk factors. We aimed to analyze the association between preoperative neurological deficit and the 30-day risk of major adverse cardiovascular events (MACEs) in CEA with selective shunting for symptomatic carotid stenosis.

METHODS

We assessed 653 patients who underwent CEA with selective shunting for symptomatic carotid stenosis between August 2011 and August 2019. The primary outcomes of the study were the occurrence of MACEs, defined as stroke (ischemic stroke or cerebral hemorrhage), all-cause mortality, and myocardial infarction during the perioperative period after CEA. Baseline patient characteristics were analyzed to identify factors associated with perioperative (<30 days) MACEs. Multivariable logistic regression models were used to estimate the association between preoperative modified Rankin Scale (mRS) and the 30-day risk of MACEs. Interaction and stratified analyses were conducted according to age, drinking, history of hypertension and coronary artery disease, and surgical side.

RESULTS

The mean age of patients was 68.7 ± 9.1 years, and 86.4% were men. The 30-day MACEs rate was 2.5%. In univariate logistic regression, histories of coronary artery disease (odds ratio (OR), 2.57 [95% confidence interval (CI), 1.04-6.34]), a severe contralateral carotid stenosis or occlusion (OR, 4.52 [95% CI, 1.84-11.11]), and a poor neurological deficit (mRS ≥ 3 versus mRS < 3: OR, 3.78 [95% CI, 1.21-11.82]) were associated with higher primary outcome rates. A history of hypertension did not increase the risk of MACEs (OR, 0.37 [95% CI, 0.15-0.89]). In the multivariable regression analysis, poor neurological deficit was associated with a higher risk of the MACEs within 30 days (mRS ≥ 3 versus mRS < 3: 11.1% vs. 2.0%, adjusted OR 5.70 [95% CI, 1.50-21.60]). The interaction analysis revealed no interactive role in the association between neurological deficit and 30-day risk of MACEs.

CONCLUSIONS

Poor neurological deficit was an independent risk factor associated with the 30-day risk of MACEs in symptomatic patients who underwent CEA with selective shunting. Our findings may provide guidance to surgeons when treating patients with poor neurological deficit. The decision to perform surgery should be made after careful consideration.

Hormone replacement therapy and prevention of chronic conditions

Nowadays, postmenopausal women are largely undertreated. Analysis of conflicting results among different studies suggests that hormone replacement therapy (HRT) can prevent osteoporosis and cardiovascular disease in symptomatic, early postmenopausal women. In fact, climacteric symptoms are related to an increased risk of chronic conditions, including hypertension and cardiovascular disease. Different scientific societies have pointed out that patient selection, timing of initiation, and the choice of the type and dose of HRT used are the major determinants of the ultimate effect of HRT on women's health and quality of life in selected women. HRT may prevent chronic conditions when started in symptomatic women before the age of 60 years or within 10 years of the onset of the menopause, taking into consideration the characteristics and risk profiles of each given woman. The bulk of scientific evidence from preclinical, clinical, epidemiological, and also randomized studies indicates that wisely selected HRT is generally useful and rarely dangerous. Following simple and well-established rules, HRT benefits outweigh all of the possible risks. Progestogen choice can make the difference in terms of cardiovascular disease benefits.

Aromatase and estrogen receptor immunoreactivity in the coronary arteries of monkeys and human subjects

OBJECTIVE

The objective of this study was to determine whether estrogen could be formed locally in the coronary arteries.

DESIGN

Coronary arteries were examined from monkeys (Macaca fascicularis, one male and one female) and human subjects (one premenopausal woman, one postmenopausal woman, and one man) by immunocytochemistry, using purified antisera against human placental estrogen synthetase (aromatase) and ER α. The arteries were graded for the amount of atherosclerosis.

RESULTS

There was clear immunopositivity for both aromatase and estrogen receptors in all arteries studied. Although all endothelial cells (CD31 positive) stained for both antigens, the staining in macrophages, fibroblasts, and smooth muscle cells was irregular.

CONCLUSION

The present results provide the first evidence for the local formation of estrogen in the coronary arteries. In addition to complementing the evidence of a cardioprotective effect of estrogen on the coronary circulation, our results highlight the potential importance of local regulation of estrogen formation and the role of available precursor androgens in maintaining the cardiovascular system.

Progesterone induces relaxation of human umbilical cord vascular smooth muscle cells through mPRα (PAQR7)

Progesterone effects on vascular smooth muscle cell (VSMC) relaxation and the mechanism were investigated in cultured human umbilical vein VSMCs. Membrane progesterone receptors mPRα, mPRβ, and mPRγ were highly expressed in VSMCs, whereas nuclear progesterone receptor (nPR) had low expression. Progesterone (20 nM) and 02-0 (mPR-selective agonist), but not R5020 (nPR agonist), induced muscle relaxation in both a VSMC collagen gel disk contraction assay and an endothelium-denuded human umbilical artery ring tension assay. Progesterone and 02-0 increased ERK and Akt phosphorylation and decreased cAMP levels. These effects were blocked by preincubation with pertussis toxin. Progestin-induced muscle relaxation was blocked by pretreatment with mPRα, but not nPR, siRNAs, and by co-treatment with 8-Br-cAMP, AZD6244 (MAP kinase inhibitor), and wortmannin (PI3K inhibitor). Progestins reduced myosin light chain phosphorylation which was blocked with AZD6244 and wortmannin. These results demonstrate progesterone directly relaxes human VSMCs through mPRα/Gi and MAP kinase/ERK-, Akt/PI3K-, and cAMP-dependent pathways.

Estrogens and Coronary Artery Disease: New Clinical Perspectives

In premenopausal women, endogenous estrogens are associated with reduced prevalence of arterial hypertension, coronary artery disease, myocardial infarction, and stroke. Clinical trials conducted in the 1990s such as HERS, WHI, and WISDOM have shown that postmenopausal treatment with horse hormone mixtures (so-called conjugated equine estrogens) and synthetic progestins adversely affects female cardiovascular health. Our understanding of rapid (nongenomic) and chronic (genomic) estrogen signaling has since advanced considerably, including identification of a new G protein-coupled estrogen receptor (GPER), which like the "classical" receptors ERα and ERβ is highly abundant in the cardiovascular system. Here, we discuss the role of estrogen receptors in the pathogenesis of coronary artery disease and review natural and synthetic ligands of estrogen receptors as well as their effects in physiology, on cardiovascular risk factors, and atherosclerotic vascular disease. Data from preclinical and clinical studies using nonselective compounds activating GPER, which include selective estrogen receptor modulators such as tamoxifen or raloxifene, selective estrogen receptor downregulators such as Faslodex™ (fulvestrant/ICI 182,780), vitamin B3 (niacin), green tea catechins, and soy flavonoids such as genistein or resveratrol, strongly suggest that activation of GPER may afford therapeutic benefit for primary and secondary prevention in patients with or at risk for coronary artery disease. Evidence from preclinical studies suggest similar efficacy profiles for selective small molecule GPER agonists such as G-1 which are devoid of uterotrophic activity. Further clinical research in this area is warranted to provide opportunities for future cardiovascular drug development.

The prognostic value of non-perfusion variables obtained during vasodilator stress myocardial perfusion imaging

Myocardial perfusion imaging (MPI) is an established diagnostic test that provides useful prognostic data in patients with known or suspected coronary artery disease. In more than half of the patients referred for stress testing, vasodilator stress is used in lieu of exercise. Unlike exercise, vasodilator stress does not provide information on exercise and functional capacity, heart rate recovery, and chronotropy, and ECG changes are less frequent. These non-perfusion data provide important prognostic and patient management information. Further, event rates in patients undergoing vasodilator MPI are higher than in those undergoing exercise MPI and even in those with normal images probably due to higher pretest risk. However, there are a number of non-perfusion variables that are obtained during vasodilator stress testing, which have prognostic relevance but their use has not been well emphasized. The purpose of this review is to summarize the prognostic values of these non-perfusion data obtained during vasodilator MPI.

Increased Cardiovascular Mortality Risk in Women Discontinuing Postmenopausal Hormone Therapy

CONTEXT

Current guidelines recommend annual discontinuation of postmenopausal hormone therapy (HT) to evaluate whether a woman could manage without the treatment. The impact of HT on cardiovascular health has been widely studied, but it is not known how the withdrawal of HT affects cardiovascular risk.

OBJECTIVE

We evaluated the risk of cardiac or stroke death after the discontinuation of HT. Design, Patients, Interventions, and Main Outcome Measures: Altogether 332 202 Finnish women discontinuing HT between 1994 and 2009 (data from National Reimbursement register) were followed up from the discontinuation date to death due to cardiac cause (n = 3177) or stroke (n = 1952), or to the end of 2009. The deaths, retrieved from the national Cause of Death Register, were compared with the expected number of deaths in the age-standardized background population. In a subanalysis we also compared HT stoppers with HT users.

RESULTS

Within the first posttreatment year, the risk of cardiac death was significantly elevated (standardized mortality ratio; 95% confidence interval 1.26; 1.16-1.37), whereas follow-up for longer than 1 year was accompanied with a reduction (0.75; 0.72-0.78). The risk of stroke death in the first posttreatment year was increased (1.63; 1.47-1.79), but follow-up for longer than 1 year was accompanied with a reduced risk (0.89; 0.85-0.94). The cardiac (2.30; 2.12-2.50) and stroke (2.52; 2.28-2.77) death risk elevations were even higher when compared with HT users. In women who discontinued HT at age younger than 60 years, but not in women aged 60 years or older, the cardiac mortality risk was elevated (1.94; 1.51-2.48).

CONCLUSIONS

Increased cardiovascular death risks question the safety of annual HT discontinuation practice to evaluate whether a woman could manage without HT.

Impacts of β-estradiol on intestinal injury in newborn rats

OBJECTIVE

Necrotizing enterocolitis has been investigated and debated extensively in recent years; however, there is still no effective treatment. The aim of this study was thus to examine the effects of β-estradiol on intestinal injury in rats.

METHODS

Twenty-four newborn female rat pups were divided into three groups. In group 1 (sham), hypoxia-re-oxygenation was not performed. In group 2 (saline), the rats were injected with saline after hypoxia-re-oxygenation, and the process was repeated for 5 d. In group 3 (β-estradiol treatment), the rats were subjected to hypoxia-re-oxygenation and then given β-estradiol intraperitoneally once a day for 5 d. After these procedures, the terminal ileum was removed for analysis.

RESULTS

Statistically significant differences in histological grades were found between groups 1 and 2 (p = 0.000), groups 1 and 3 (p = 0.028), and groups 2 and 3 (p = 0.021). There were also differences in TNF-α and IL-6 levels between groups 2 and 3 (p = 0.000 and p = 0.038, respectively) and between groups 1 and 2 (p = 0.000 and p = 0.000); there was no difference between groups 1 and 3 (p = 0.574 and p = 0.195, respectively). Electron microscopy examination revealed a decrease in lipid droplets at the apical cytoplasm of the columnar cells in group 2; in group 3, the absorption of the lipids as lipid droplets was similar to that of group 1.

CONCLUSION

In this study, β-estradiol was found to decrease the intensity of intestinal injury significantly by inhibiting TNF-α and IL-6.

Sex-based differences in cardiac ischaemic injury and protection: therapeutic implications

Ischaemic heart disease (IHD) is the most frequent cause of mortality among men and women. Many epidemiological studies have demonstrated that premenopausal women have a reduced risk for IHD compared with their male counterparts. The incidence of IHD in women increases after menopause, suggesting that IHD is related to declining oestrogen levels. Experimental observations have confirmed the results of epidemiological studies investigating sex-specific differences in cardiac tolerance to ischaemia. Female sex appears also to favourably influence cardiac remodelling after ischaemia/reperfusion injury. Furthermore, sex-related differences in ischaemic tolerance of the adult myocardium can be influenced by interventions during the early phases of ontogenetic development. Detailed mechanisms of these sex-related differences remain unknown; however, they involve the genomic and non-genomic effects of sex steroid hormones, particularly the oestrogens, which have been the most extensively studied. Although the protective effects of oestrogen have many potential therapeutic implications, clinical trials have shown that oestrogen replacement in postmenopausal women may actually increase the incidence of IHD. The results of these trials have illustrated the complexity underlying the mechanisms involved in sex-related differences in cardiac tolerance to ischaemia. Sex-related differences in cardiac sensitivity to ischaemia/reperfusion injury may also influence therapeutic strategies in women with acute coronary syndrome. Women undergo coronary intervention less frequently and a lower proportion of women receive evidence-based therapy compared with men. Although our understanding of this important topic has increased in recent years, there is an urgent need for intensive experimental and clinical research to develop female-specific therapeutic strategies. Only then we will be able to offer patients better evidence-based treatment, a better quality of life and lower mortality.

Sex hormone replacement therapy and modulation of vascular function in cardiovascular disease

Epidemiological and experimental studies suggest vascular protective effects of estrogen. Cardiovascular disease (CVD) is less common in premenopausal women than in men and postmenopausal women. Cytosolic/nuclear estrogen receptors (ERs) have been shown to mediate genomic effects that stimulate endothelial cell growth but inhibit vascular smooth muscle proliferation. However, the Heart and Estrogen/Progestin Replacement Study (HERS), HERS-II and Women's Health Initiative clinical trials demonstrated that hormone replacement therapy (HRT) may not provide vascular benefits in postmenopausal women and may instead trigger adverse cardiovascular events. HRT may not provide vascular benefits because of the type of hormone used. Oral estrogens are biologically transformed by first-pass metabolism in the liver. By contrast, transdermal preparations avoid first pass metabolism. Also, natural estrogens and phytoestrogens may provide alternatives to synthetic estrogens. Furthermore, specific ER modulators could minimize the adverse effects of HRT, including breast cancer. HRT failure in CVD could also be related to changes in vascular ERs. Genetic polymorphism and postmenopausal decrease in vascular ERs or the downstream signaling mechanisms may reduce the effects of HRT. HRT in the late postmenopausal period may not be as effective as during menopausal transition. Additionally, while HRT may aggravate pre-existing CVD, it may thwart its development if used in a timely fashion. Lastly, the vascular effects of progesterone and testosterone, as well as modulators of their receptors, may modify the effects of estrogen and thereby provide alternative HRT strategies. Thus, the beneficial effects of HRT in postmenopausal CVD can be enhanced by customizing the HRT type, dose, route of administration and timing depending on the subject's age and cardiovascular condition.

Protective actions of progesterone in the cardiovascular system: potential role of membrane progesterone receptors (mPRs) in mediating rapid effects

The protective functions of progesterone in the cardiovascular system have received little attention even though evidence has accumulated that progesterone lowers blood pressure, inhibits coronary hyperactivity and has powerful vasodilatory and natriuretic effects. One possible reason why potential beneficial actions of progesterone on cardiovascular functions have not been extensively studied is that divergent effects to those of progesterone have been observed in many clinical trials with synthetic progestins such as medroxyprogesterone acetate which are associated with increased risk of coronary disease. Evidence that progesterone exerts protective effects on cardiovascular functions is briefly reviewed. The finding that progesterone administration decreases blood vessel vasoconstriction in several animal models within a few minutes suggests that rapid, nongenomic progesterone mechanisms are of physiological importance in regulating vascular tone. Rapid activation of second messenger pathways by progesterone has been observed in vascular endothelial and smooth muscle cells, resulting in alterations in endothelial nitric oxide synthase (eNOS) activity and calcium influx, respectively. Both nuclear progesterone receptors (PRs) and novel membrane progesterone receptors (mPRs) are candidates for the intermediaries in these rapid, cell-surface initiated progesterone actions in endothelial and smooth muscle vascular cells. PRs have been detected in both cell types. New data are presented showing mPRα, mPRβ and mPRγ are also present in human endothelial and smooth muscle vascular cells. Preliminary evidence suggests mPRs mediate rapid progestin signaling in these endothelial cells, resulting in down-regulation of cAMP production and increased nitric oxide synthesis. The role of mPRs in progesterone regulation of cardiovascular functions warrants further investigation.

Cardiac disease associated with increased risk of nonamnestic cognitive impairment: stronger effect on women

OBJECTIVE

To investigate the association of cardiac disease with amnestic and nonamnestic mild cognitive impairment (aMCI and naMCI, respectively). Nonamnestic mild cognitive impairment, a putative precursor of vascular and other non-Alzheimer dementias, is hypothesized to have a vascular etiology.

DESIGN

A prospective, population-based, cohort study with a median 4.0 years of follow-up.

SETTING

Olmsted County, Minnesota.

PARTICIPANTS

A total of 2719 participants were evaluated at baseline and every 15 months using the Clinical Dementia Rating scale, a neurological evaluation, and neuropsychological testing. A diagnosis of normal cognition, MCI, or dementia was made by consensus. Cardiac disease at baseline was assessed from the participant's medical records.

MAIN OUTCOME MEASURES

Incident MCI, aMCI, or naMCI.

RESULTS

Of 1450 participants without MCI or dementia at baseline, 366 developed MCI. Cardiac disease was associated with an increased risk of naMCI (hazard ratio, 1.77 [95% CI, 1.16-2.72]). However, the association varied by sex (P = .02 for interaction). Cardiac disease was associated with an increased risk of naMCI (hazard ratio, 3.07 [95% CI, 1.58-5.99]) for women but not for men (hazard ratio, 1.16 [95% CI, 0.68-1.99]). Cardiac disease was not associated with any type of MCI or with aMCI.

CONCLUSIONS

Cardiac disease is an independent risk factor for naMCI; within-sex comparisons showed a stronger association for women. Prevention and management of cardiac disease and vascular risk factors may reduce the risk of naMCI.

Clinical characteristics, sex hormones, and long-term follow-up in Swiss postmenopausal women presenting with Takotsubo cardiomyopathy

BACKGROUND

The overwhelming majority of patients with stress cardiomyopathy (SC) are postmenopausal women, suggesting an important pathophysiologic role of the female sex hormones. Preliminary data suggest that myocardial stunning might be provoked by estrogen deficiency.

HYPOTHESIS

We hypothesized that, compared with age- and gender-matched patients with myocardial infarction (MI) or patients with normal coronary arteries, patients with SC would exhibit altered levels of sex hormones. Furthermore, we aimed to describe the clinical course and the pattern of sex hormones of the SC patients during long-term follow-up.

METHODS

Blood samples obtained on hospital admission were analyzed for estradiol (E2), progesterone (P), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) in women with SC (n = 17), age-matched women with acute MI (n = 16), and women with normal coronary arteries (n = 15). Six years after the initial event, SC patients underwent a clinical and echocardiographic follow-up and reassessment of sex hormones.

RESULTS

Estrogen concentrations at hospital admission were significantly higher in the SC group compared with the MI and the control groups, with no difference in P, FSH, and LH concentrations. Follow-up E2 after 6 years in SC patients was lower than during the acute SC episode. Follow-up P in these patients was lower than P in the MI and control groups during the acute event, with a similar trend for E2. After a median follow-up of 6.4 years, 1 sudden cardiac death occurred and 2 patients suffered from SC recurrence.

CONCLUSIONS

During the acute event, E2 concentrations are elevated in postmenopausal SC patients compared with women with acute MI or with normal coronary arteries. The higher E2 concentrations might have exerted atheroprotective effects and thus diverted the stress response to SC rather than MI. Recurrence and/or sudden cardiac death remains a potential risk of SC.

Role of neuronal nitric-oxide synthase in estrogen-induced relaxation in rat resistance arteries

Estrogen has antihypertensive and vasorelaxing properties, partly via activation of endothelial nitric-oxide synthase (eNOS). Recently, neuronal nitric-oxide synthase (nNOS) has been detected in vascular cells, although the significance of this is unclear. Estrogen was found to stimulate nNOS in certain cultured cells. We hypothesized that estrogen regulates vascular tone partly via endothelium-derived nNOS. Human umbilical vein endothelial cells were used to test whether acute (5 min) stimulation with 17β-estradiol (E2) at 1 or 10 nM affected nNOS activity. Small mesenteric arteries from Sprague-Dawley rats were examined for relaxation to E2 (0.001-10 μM) in the absence or presence of selective nNOS inhibitor [N-propyl-L-arginine (L-NPA); 2 μM] or pan-NOS inhibitor [Nω-nitro-L-arginine methyl ester (L-NAME); 100 μM] using a wire myograph. Immunostaining was used to visualize nNOS in rat mesenteric artery cross-sections. Western blotting measured total and phospho-nNOS in endothelial cell lysates and thoracic aorta homogenates. E2 rapidly increased (p < 0.001) activating phosphorylation of nNOS and nitric oxide (NO) production (as measured by 4-amino-5-methylamino-2,7-difluorofluorescein fluorescence) in endothelial cells. Likewise, E2 caused dose-dependent relaxation of arteries from female rats, which was blunted by both l-NPA and l-NAME (p < 0.001). In contrast, E2 response was modest in male animals and unaffected by NOS inhibition. It is noteworthy that there was a greater baseline presence of phospho-nNOS in male relative to female aortas. Although eNOS is believed to be the main source of NO in the vascular endothelium, we confirmed nNOS expression in endothelial cells. Endothelial nNOS mediated E2 relaxation in isolated arteries from female animals. Altogether, these data suggest vascular nNOS as a novel mechanism in E2 signaling.

Experimental benefits of sex hormones on vascular function and the outcome of hormone therapy in cardiovascular disease

Cardiovascular disease (CVD) is more common in men and postmenopausal women than premenopausal women, suggesting vascular benefits of female sex hormones. Experimental data have shown beneficial vascular effects of estrogen including stimulation of endothelium-dependent nitric oxide, prostacyclin and hyperpolarizing factor-mediated vascular relaxation. However, the experimental evidence did not translate into vascular benefits of hormone replacement therapy (HRT) in postmenopausal women, and HERS, HERS-II and WHI clinical trials demonstrated adverse cardiovascular events with HRT. The lack of vascular benefits of HRT could be related to the hormone used, the vascular estrogen receptor (ER), and the subject’s age and preexisting cardiovascular condition. Natural and phytoestrogens in small doses may be more beneficial than synthetic estrogen. Specific estrogen receptor modulators (SERMs) could maximize the vascular benefits, with little side effects on breast cancer. Transdermal estrogens avoid the first-pass liver metabolism associated with the oral route. Postmenopausal decrease and genetic polymorphism in vascular ER and post-receptor signaling mechanisms could also modify the effects of HRT. Variants of cytosolic/nuclear ER mediate transcriptional genomic effects that stimulate endothelial cell growth, but inhibit vascular smooth muscle (VSM) proliferation. Also, plasma membrane ERs trigger not only non-genomic stimulation of endothelium-dependent vascular relaxation, but also inhibition of [Ca²⁺]i, protein kinase C and Rho kinase-dependent VSM contraction. HRT could also be more effective in the perimenopausal period than in older postmenopausal women, and may prevent the development, while worsening preexisting CVD. Lastly, progesterone may modify the vascular effects of estrogen, and modulators of estrogen/testosterone ratio could provide alternative HRT combinations. Thus, the type, dose, route of administration and the timing/duration of HRT should be customized depending on the subject’s age and preexisting cardiovascular condition, and thereby make it possible to translate the beneficial vascular effects of sex hormones to the outcome of HRT in postmenopausal CVD.

Impact of sex hormone metabolism on the vascular effects of menopausal hormone therapy in cardiovascular disease

Epidemiological studies have shown that cardiovascular disease (CVD) is less common in pre-menopausal women (Pre-MW) compared to men of the same age or post-menopausal women (Post-MW), suggesting cardiovascular benefits of estrogen. Estrogen receptors (ERs) have been identified in the vasculature, and experimental studies have demonstrated vasodilator effects of estrogen/ER on the endothelium, vascular smooth muscle (VSM) and extracellular matrix. Several natural and synthetic estrogenic preparations have been developed for relief of menopausal vasomotor symptoms. However, whether menopausal hormone therapy (MHT) is beneficial in postmenopausal CVD remains controversial. Despite reports of vascular benefits of MHT from observational and experimental studies, randomized clinical trials (RCTs), such as the Heart and Estrogen/progestin Replacement Study (HERS) and the Women's Health Initiative (WHI), have suggested that, contrary to expectations, MHT may increase the risk of CVD. These discrepancies could be due to agerelated changes in sex hormone synthesis and metabolism, which would influence the effective dose of MHT and the sex hormone environment in Post-MW. Age-related changes in the vascular ER subtype, structure, expression, distribution, and post-ER signaling pathways in the endothelium and VSM, along with factors related to the design of RCTs, preexisting CVD condition, and structural changes in the blood vessels architecture have also been suggested as possible causes of MHT failure in CVD. Careful examination of these factors should help in identifying the causes of the changes in the vascular effects of estrogen with age. The sex hormone metabolic pathways, the active versus inactive estrogen metabolites, and their effects on vascular function, the mitochondria, the inflammatory process and angiogenesis should be further examined. Also, the genomic and non-genomic effects of estrogenic compounds should be viewed as integrated rather than discrete responses. The complex interactions between these factors highlight the importance of careful design of MHT RCTs, and the need of a more customized approach for each individual patient in order to enhance the vascular benefits of MHT in postmenopausal CVD.

VWF and ADAMTS13 behavior in estradiol-treated HUVEC

OBJECTIVES

In this study, the role of 17β-estradiol (E2) in the regulation of von Willebrand factor (VWF) and ADAMTS13 synthesis, storage, and secretion was investigated in cultured human umbilical vein endothelial cells (HUVEC).

METHODS

HUVEC were grown to 80-90% confluence and replaced with fresh medium containing E2 (1 nm) or vehicle for 24 h, after which the supernatant medium and cell lysates were collected to measure VWF and ADAMTS13. VWF was evaluated by VWF:Ag and multimeric analysis. ADAMTS13 was evaluated by SDS-PAGE. VWF and ADAMTS13 mRNA were quantified by real-time PCR after E2 or vehicle exposure for 18 h. A functional effect of ADAMTS13 on HUVEC VWF protein synthesis was further evaluated using a short hairpin RNA (shRNA) to knockdown the expression of endogenous ADAMTS13.

RESULTS

E2 did not increase the release or intracellular VWF levels in HUVEC. However, E2 increased the production of intracellular ADAMTS13, although there was no evidence of significant effects of their release into culture medium. Incubation of HUVEC with E2 resulted in a significantly increased expression of VWF and ADAMTS13 mRNA. ADAMTS13 gene inactivation upregulates release and intracellular VWF levels in E2-treated HUVEC.

CONCLUSION

The results demonstrated that E2 may play a role in the regulation of VWF and ADAMTS13 gene expression and in its production in human endothelial cells. The mechanism of the protective effects of E2 on the cardiovascular system could be explained by the intracellular regulation of VWF produced by ADAMTS13.

Ischaemic heart disease in women: are there sex differences in pathophysiology and risk factors? Position paper from the working group on coronary pathophysiology and microcirculation of the European Society of Cardiology

Cardiovascular disease (CVD) is the leading cause of death in women, and knowledge of the clinical consequences of atherosclerosis and CVD in women has grown tremendously over the past 20 years. Research efforts have increased and many reports on various aspects of ischaemic heart disease (IHD) in women have been published highlighting sex differences in pathophysiology, presentation, and treatment of IHD. Data, however, remain limited. A description of the state of the science, with recognition of the shortcomings of current data, is necessary to guide future research and move the field forward. In this report, we identify gaps in existing literature and make recommendations for future research. Women largely share similar cardiovascular risk factors for IHD with men; however, women with suspected or confirmed IHD have less coronary atherosclerosis than men, even though they are older and have more cardiovascular risk factors than men. Coronary endothelial dysfunction and microvascular disease have been proposed as important determinants in the aetiology and prognosis of IHD in women, but research is limited on whether sex differences in these mechanisms truly exist. Differences in the epidemiology of IHD between women and men remain largely unexplained, as we are still unable to explain why women are protected towards IHD until older age compared with men. Eventually, a better understanding of these processes and mechanisms may improve the prevention and the clinical management of IHD in women.

Estrogen and oxidative stress: A novel mechanism that may increase the risk for cardiovascular disease in women

Although early studies demonstrated that exogenous estrogen lowered a woman's risk of cardiovascular disease, recent trials indicate that HRT actually increases the risk of coronary heart disease or stroke. However, there is no clear explanation for this discrepancy. Is estrogen a helpful or a harmful hormone in terms of cardiovascular function? This review discusses some recent findings that propose a novel mechanism which may shed significant light upon this controversy. We propose that nitric oxide synthase (NOS) expressed within the vascular wall is a target of estrogen action. Under normal conditions in younger women, the primary product of estrogen action is NO, which produces a number of beneficial effects on vascular biology. As a woman ages, however, there is evidence for loss of important molecules essential for NO production (e.g., tetrahydrobiopterin, l-arginine). As these molecules are depleted, NOS becomes increasingly "uncoupled" from NO production, and instead produces superoxide, a dangerous reactive oxygen species. We propose that a similar uncoupling and reversal of estrogen response occurs in diabetes. Therefore, we propose that estrogen is neither "good" nor "bad", but simply stimulates NOS activity. It is the biochemical environment around NOS that will determine whether estrogen produces a beneficial (NO) or deleterious (superoxide) product, and can account for this dual and opposite nature of estrogen pharmacology. Further, this molecular mechanism is consistent with recent analyses revealing that HRT produces salutary effects in younger women, but mainly increases the risk of cardiovascular dysfunction in older postmenopausal women.

A randomized controlled trial of low-dose hormone therapy on myocardial ischemia in postmenopausal women with no obstructive coronary artery disease: results from the National Institutes of Health/National Heart, Lung, and Blood Institute-sponsored Women's Ischemia Syndrome Evaluation (WISE)

BACKGROUND

Compared with men, women have more evidence of myocardial ischemia with no obstructive coronary artery disease. Although low endogenous estrogen levels are associated with endothelial dysfunction, the role of low-dose hormone therapy has not been fully evaluated. We postulate that a 12-week duration of low-dose hormone replacement therapy is associated with myocardial ischemia and endothelial dysfunction.

METHODS AND RESULTS

Using a multicenter, randomized, placebo-controlled design, subjects were randomized to receive either 1 mg norethindrone/10 microg ethinyl estradiol or placebo for 12 weeks. Chest pain and menopausal symptoms, cardiac magnetic resonance spectroscopy, brachial artery reactivity, exercise stress testing, and psychosocial questionnaires were evaluated at baseline and exit. Recruitment was closed prematurely because of failure to recruit after publication of the Women's Health Initiative hormone trial. Of the 35 women who completed the study, there was less frequent chest pain in the treatment group compared with the placebo group (P = .02) at exit. Women taking 1 mg norethindrone/10 microg ethinyl estradiol also had significantly fewer hot flashes/night sweats (P = .003), less avoidance of intimacy (P = .05), and borderline differences in sexual desire and vaginal dryness (P = .06). There were no differences in magnetic resonance spectroscopy, brachial artery reactivity, compliance, or reported adverse events between the groups.

CONCLUSIONS

These data suggest that low-dose hormone therapy improved chest pain symptoms, menopausal symptoms, and quality of life, but did not improve ischemia or endothelial dysfunction. Given that it was not possible to enroll the prespecified sample size, these results should not be considered definitive.

Hormone Replacement Therapy: A Critical Review

The aim of this chapter is to review the most recent aspects of hormone replacement therapy (HRT), and to clarify its impact on associated health conditions amidst growing uncertainties. Special emphasis has been placed on its effect on cardiovascular conditions and breast cancer, the two most important outcomes affected by HRT, and on identifying ideal candidates for HRT as well as defining the optimum new HRT regimens.

Estrogen after ischemic stroke: clinical basis and design of the Women's Estrogen for Stroke Trial

BACKGROUND AND PURPOSE

Observational studies have found that women who take estrogen after menopause are less likely to have a stroke than women who do not take estrogen. Although these findings indicate that estrogen may prevent stroke, an alternative explanation for the improved outcome of estrogen users is that they are healthier before starting therapy than nonusers. To test the therapeutic effect of estrogen with research methods that avoid this selection bias, we designed a randomized controlled trial.

TRIAL DESIGN

The Women's Estrogen For Stroke Trial (WEST) is a double-blind, randomized trial with a primary goal of determining whether 1 mg 17beta-estradiol daily, when compared with placebo, reduces the risk of recurrent stroke or death among postmenopausal women who have experienced a transient ischemic attack or nondisabling ischemic stroke. Exclusion criteria include use of estrogen at the time of stroke, breast or uterine cancer, inability to speak English, and estimated survival less than 5 years. Once randomized, women remain under the care of their personal physicians for management of stroke risk factors. For early detection of endometrial hyperplasia and cancer, asymptomatic women receive medroxyprogesterone yearly (5 mg for 12 days) and vaginal ultrasonography or biopsy at the end of the trial. Unscheduled uterine bleeding is evaluated with biopsy. A total of 652 women are sought at 20 hospitals in Connecticut and one in Massachusetts.

CONCLUSIONS

The WEST promises to provide critical guidance to women and their physicians regarding the effectiveness of estrogen in secondary stroke prevention.

Long-term dietary patterns and carotid artery intima media thickness: the Cardiovascular Risk in Young Finns Study

A whole-diet approach has proven useful for characterising dietary exposure in cardiovascular epidemiology research. In our previous analyses, we found dietary patterns to be significant determinants of CVD risk factor levels among the Cardiovascular Risk in Young Finns cohort. We investigated the associations of major dietary patterns with carotid intima media thickness (IMT), a subclinical predictor of CVD, in healthy adults. The Young Finns Study is an ongoing, prospective cohort study with a 21-year follow-up to date. The subjects were children and adolescents at baseline in 1980 (aged 3-18 years), and all had reached adulthood by the latest follow-up in 2001 (aged 24-39 years). Complete dietary data from the years 1980, 1986 and 2001 and outcome data from the year 2001 were obtained from 785 subjects. The long-term average pattern score for a traditional dietary pattern (characterised by high consumption of rye, potatoes, butter, sausages, milk and coffee) was associated with IMT especially among subjects with a low score for the health-conscious dietary pattern (characterised by high consumption of vegetables, legumes and nuts, rye, tea, cheese and other dairy products). In multivariable regression analyses using long-term pattern scores as predictors, the traditional dietary pattern was independently associated with IMT in men (P < 0.01), but not in women (P = 0.66). Long-term adherence to traditional food choices seems to increase the risk of developing subclinical atherosclerosis among Finnish men.

Mitochondrial benzodiazepine receptors mediate cardioprotection of estrogen against ischemic ventricular fibrillation

The cardioprotective effects of estrogen remain controversial in clinical practice. Previous reports have shown that cardioprotective mechanisms converge on the mitochondria, but the role of mitochondria in estrogen's actions on cardiac arrhythmias is unclear. Here, we report that stimulation or inhibition of mitochondrial benzodiazepine receptors (mBzR) affected ventricular fibrillation (VF) almost in an "all-or-none" manner in an in vitro rat heart model of ischemic VF. Low concentrations of estrogen did not provide antiarrhythmic effects; however, the combination of mBzR activator and estrogen reduced VF incidence in hearts from either gender. Such synergistic actions also enabled cardiomyocytes to resist metabolic stress-induced intracellular [Ca(2+)](i) overload. Ligand binding experiments revealed that estrogen itself did not affect mBzR activity under basal conditions but promoted its up-regulation under myocardial ischemia. Our results suggest that mBzR may be an important molecule for ischemic arrhythmia and may act as a molecular switch for estrogen's antiarrhythmic effects. This finding provides a clue for elucidating the conflicting results regarding estrogen's cardiac effects in clinical studies and also suggests potential new strategies for hormone treatment in the female population.

[Effects of a structured exercise programme on cardiovascular risk programmes in post-menopausal women. CLIDERICA study]

OBJECTIVE

To analyse the influence of a physical exercise programme of strength/stamina on cardiovascular risk factors in low-risk post-menopausal women.

DESIGN

Six-month randomised clinical trial with post-menopausal women.

SETTING

Three health centres in the autonomous community of Murcia, Spain.

PARTICIPANTS

Sixty-three post-menopausal women aged 45 to 59 at low cardiovascular risk. INTERVENTIONS AND MAIN MEASUREMENTS: They were split into 2 groups: a) control: 23 people with no specific intervention, and b) 40 people with an intervention of strength/stamina exercise with protocol for in water and on land. At their initial and final visits, everyone in the 2 groups had anamnesis, physical examination, and general analyses, including Apo A, Apo B, insulin, serum creatinine, creatinine clearance, creatinine in urine, albuminuria, ultrasensitive PCR, and HOMA index.

RESULTS

The insulin levels increased in the control group by 2.02 mU/L and dropped in the experimental group by 0.13 mU/L (P=.021). At the start of the study, creatinine in the control group was 0.83+/-0.12 mg/dL; and at the end, 0.91+/-0.02 mg/dL. In the intervention group it was 0.84+/-0.12 mg/dL at the start and 0.90+/-0.13 mg/dL at the end (NS). Systolic blood pressure dropped in both groups, with a bigger drop in the exercise group (11.81 vs 0.17 mm Hg) (P=.0001). HDL-C values increased in the control group by 4.97 mg/dL; and in the experimental group, by 3.46 mg/dL (NS).

CONCLUSIONS

A controlled programme of strength/stamina physical exercise reduces the cardiovascular risk of post-menopausal women.

Estrogen-induced improvement in coronary flow responses during atrial pacing in relation to endothelin-1 levels in postmenopausal women without coronary disease

BACKGROUND

The cardioprotective role of hormonal replacement therapy remains in doubt, but interest is increasing in the vascular effects of estrogens especially in coronary circulation.

METHODS

Coronary blood flow (CBF) was measured in 24 postmenopausal women (age 55+/-3 years), whose coronary arteries appeared angiographically normal, during incremental atrial pacing (AP) before and 20 minutes after intracoronary administration of either 75 ng/mL 17-beta estradiol (treated group, n=18) or 0.9% saline (controls, n=6).

RESULTS

Before estrogen, no differences in the coronary vasomotor responses at AP between the two groups (p=NS) could be detected. After estrogen, in the treated group, at the peak of the second AP, the coronary artery diameter decreased by 0.17 mm (p<0.005) while the CBF increased by 61 mL/min (p<0.05). These changes differed significantly from those observed at the peak of first AP (p<0.001 for both cases). In contrast, in the control group no such changes were observed. The endothelin-1 (ET-1) levels in the coronary sinus were significantly reduced after estrogen infusion, which was negatively correlated with the degree of coronary artery constriction (r= -0.40, p=0.03) and positively correlated with the increase in CBF (r=0.54, p=0.01).

CONCLUSIONS

In postmenopausal women without coronary artery disease, the intracoronary estrogen infusion mediates a greater increase in CBF and is positively correlated with the reduction of the coronary sinus ET-1 levels at the peak of AP.

Dobutamine stress cardiac magnetic resonance imaging to detect myocardial ischemia in women

This study sought to evaluate dobutamine stress cardiac magnetic resonance imaging (DCMRI) in women with abnormal stress nuclear testing results. Women with findings on stress nuclear exams, including electrocardiography and/or perfusion, thought to require further evaluation with invasive coronary angiography were prospectively enrolled. Multiplane cine imaging was obtained at rest and at each stage of inotropic stress with atropine as needed to achieve target heart rate. DCMRI results were compared with stress nuclear and invasive cardiac catheterization results. Of 23 patients enrolled successfully, 22 completed DCMRI examination without complications. In all cases, DCMRI imaging demonstrated appropriate stress response with no ischemia despite abnormalities on stress nuclear testing. In the 18 patients who also underwent invasive coronary angiography, no significant obstructive disease was identified. DCMRI may be a useful alternative to stress nuclear examination in women; larger studies are warranted to determine its potential to more accurately predict obstructive coronary artery disease.

Sex steroids and vascular responses in hypertension and aging

BACKGROUND

Sex hormones play a significant role in human physiology. Estrogen may have protective effects in the cardiovascular system, as evidenced by the decreased incidence of cardiovascular disease (CVD) in premenopausal compared with postmenopausal women.

OBJECTIVE

This review highlights the acute and long-term effects of sex hormones on the vascular endothelium and vascular smooth muscle (VSM) in adults. Changes in the sex hormone mix, their receptors, and their effects on vascular function in hypertension and aging are also discussed.

METHODS

Literature collected from the National Centers for Biotechnology Information as identified by a PubMed database search, as well as our experimental work, was used to highlight current knowledge regarding vascular responses to sex hormones in hypertension and in aging.

RESULTS

Experiments in adult female animals have shown that estrogen induces endothelium-dependent vascular relaxation via the nitric oxide (NO), prostacyclin, and hyperpolarization pathways. Also, surface membrane estrogen receptors (ERs) decrease intracellular free Ca2+ concentration and perhaps protein kinase C-dependent VSM contraction. However, clinical trials such as the Heart and Estrogen/progestin Replacement Study (HERS), HERS-II, and the Women's Health Initiative did not support the experimental findings and demonstrated adverse cardiovascular events of hormone therapy (HT) in aging women. The lack of vascular benefits of HT may be related to the hormone used, the ER, or the patient's cardiovascular condition or age. Experiments on vascular strips from aging (16-month-old) female spontaneously hypertensive rats have shown reduced ER-mediated NO production from endothelial cells and decreased inhibitory effects of estrogen on Ca2+ entry mechanisms of VSM contraction. The age-related decrease in ER-mediated vascular relaxation may explain the decreased effectiveness of HT on CVD in aging women.

CONCLUSIONS

New HT strategies should further examine the benefits of natural estrogens and phytoestrogens. Transdermal estrogen may be more effective than the oral form, and specific ER modulators may maximize the vascular benefits and reduce the risk of invasive breast cancer. Variants of vascular ERs should be screened for genetic polymorphisms and postmenopausal decrease in the amount of downstream signaling mechanisms. HT may be more effective during the menopausal transition than in late menopause. Progesterone, testosterone, or their specific modulators may be combined with estrogen to provide alternative HT strategies. Thus, HT type, dose, route of administration, and timing should be customized, depending on the patient's cardiovascular condition and age, thereby enhancing the vascular benefits of HT in aging women.

Sex influences the susceptibility to reperfusion-induced sustained ventricular tachycardia and β-adrenergic receptor blockade in conscious rats

Reperfusion after a brief period of cardiac ischemia can lead to potentially lethal arrhythmias. Importantly, there are sex-related differences in cardiac physiology and in the types and severity of cardiac arrhythmias. Therefore, we tested the hypothesis that gonadal hormones influence the susceptibility to reperfusion-induced sustained ventricular tachycardia (VT), as well as the response to β-adrenergic receptor blockade. Male and female intact and gonadectomized rats were instrumented, and arterial pressure, temperature, ECG, and cardiac output were recorded. In addition, a snare was placed around the left main coronary artery. Tension was applied to the snare for determination of susceptibility to sustained VT produced by 3 min of occlusion and reperfusion of the left main coronary artery in conscious rats. Reperfusion culminated in sustained VT in 77% (10 of 13 susceptible) of female rats and 56% (9 of 16 susceptible) of male rats ( P > 0.05, male vs. female). β-Adrenergic receptor blockade prevented sustained VT in females only [1 of 9 susceptible females (11%) vs. 6 of 9 susceptible males (67%), P < 0.05]. Ovariectomy did not significantly reduce the susceptibility to reperfusion arrhythmias [5 of 9 susceptible (56%)]. In sharp contrast, orchidectomy significantly increased the susceptibility to reperfusion arrhythmias [9 of 9 susceptible (100%)]. Finally, β-adrenergic receptor blockade prevented sustained VT in ovariectomized females [0 of 4 susceptible (0%)] and orchidectomized males [0 of 7 susceptible (0%)], but the protective effect of β-blockade was due to a reduction in heart rate in males only. Thus gonadal hormones influence the susceptibility to reperfusion-induced arrhythmias, as well as the effects and mechanisms of β-adrenergic receptor blockade.

Prognostic significance of asymptomatic coronary artery disease in patients with diabetes and need for early revascularization therapy

AIMS

Information on the clinical outcome of patients with diabetes with silent myocardial ischaemia is limited. We compared the clinical and angiographic characteristics, and the clinical outcomes of diabetic patients with asymptomatic or symptomatic coronary artery disease (CAD).

METHODS

Three hundred and ten consecutive diabetic patients with CAD were divided into two groups according to the presence of angina and followed for a mean of 5 years. Fifty-six asymptomatic patients with a positive stress test and CAD on coronary angiography were compared with 254 symptomatic patients, 167 with unstable angina and 87 with chronic stable angina.

RESULTS

Although the severity of coronary atherosclerosis was similar in asymptomatic and symptomatic patients, revascularization therapy was performed less frequently in the asymptomatic than the symptomatic patients (26.8 vs. 62.0%; P < 0.001). Asymptomatic patients experienced a similar number of major adverse cardiac events (MACEs; death, non-fatal myocardial infarction, and revascularization; 32 vs. 28%; P = 0.57), but had higher cardiac mortality than symptomatic patients (26 vs. 9%; P < 0.001). However, patients who underwent revascularization therapy at the time of CAD diagnosis in these two groups showed similar MACE and cardiac mortality (20.0 vs. 22.5%, 6.7 vs. 5.3%, respectively; all P > 0.05).

CONCLUSIONS

This study suggests that diabetic patients with asymptomatic CAD have a higher cardiac mortality risk than those with symptomatic CAD, and that lack of revascularization therapy may be responsible for the poorer survival.

Cardiovascular health and the menopause: the gynecologist as the patients' interface

The large decrease in estrogen following menopause appears to explain the dramatic increase in cardiovascular disease (CVD) in postmenopausal women. Gynecologists are well placed to play a primary role in the diagnosis, prevention and management of CVD in these patients; this role may include advice on lifestyle changes, and, if appropriate, prescribing preventative treatments such as hormone replacement therapy (HRT) and lipid-lowering drugs. The use of estrogen replacement therapy (ERT) to prevent CVD is supported by a number of observational studies. However, recently, large, randomized trials gave unexpected, conflicting data on the cardiovascular benefits of HRT, leading to confusion, and influencing both patient and clinical perceptions regarding the role of HRT postmenopause. These different outcomes may be due to differences in the HRT regimens, mean age and mean time from menopause at enrollment, duration of therapy, and patient selection bias in observational studies. A 'unified hypothesis' consistent with findings from all studies has now been developed: HRT initiated at the time of the menopause prevents CVD, whereas HRT initiated years after the menopause seems to increase CHD events. This knowledge is essential for gynecologists making clinical decisions regarding HRT use.

Sex hormones, vascular function and the outcome of hormone replacement therapy in cardiovascular disease

Cardiovascular disease is more common in men and post-menopausal women than premenopausal women, suggesting that female sex hormones have vascular benefits. Cytosolic/nuclear estrogen and progesterone receptors mediate genomic transcriptional effects that stimulate endothelial cell growth and inhibit smooth muscle proliferation. Sex hormone receptors on the plasma membrane trigger nongenomic stimulation of endothelium-dependent nitric oxide–cyclic (c)GMP, prostacyclin–cAMP and hyperpolarizing vascular relaxation pathways, as well as inhibition of [Ca2+]i, protein kinase C and Rho-kinase-dependent mechanisms of smooth muscle contraction. Despite the vasodilator effects of sex hormones, the Heart and Estrogen/progestin Replacement Study (HERS), HERS-II and Women’s Health Initiative clinical trials have shown minimal benefits of hormone replacement therapy (HRT) in post-menopausal cardiovascular disease. The prospect of HRT relies on further mechanistic analysis of the vascular effects of natural sex hormones and phytoestrogens, and the identification of specific estrogen receptor modulators. Androgens have vascular effects, and modulators of the estrogen/testosterone ratio could provide better HRT combinations. The timing/duration and the type, dose and route of administration of HRT should be customized according to the subject’s age and pre-existing cardiovascular condition, thereby enhancing the outcome of HRT in cardiovascular disease.

Nongenomic, endothelium-independent effects of estrogen on human coronary smooth muscle are mediated by type I (neuronal) NOS and PI3-kinase-Akt signaling

Sex steroids exert profound and controversial effects on cardiovascular function. For example, estrogens have been reported to either ameliorate or exacerbate coronary heart disease. Although estrogen dilates coronary arteries from a variety of species, the molecular basis for this acute, nongenomic effect is unclear. Moreover, we know very little of how estrogen affects human coronary artery smooth muscle cells (HCASMC). The purpose of this study was to elucidate nongenomic estrogen signal transduction in HCASMC. We have used tissue (arterial tension studies), cellular (single-channel patch clamp, fluorescence), and molecular (protein expression) techniques to now identify novel targets of estrogen action in HCASMC: type I (neuronal) nitric oxide synthase (nNOS) and phosphatidylinositol 3-kinase (PI3-kinase)Akt. 17beta-Estradiol (E(2)) increased NO-stimulated fluorescence in HCASMC, and cell-attached patch-clamp experiments revealed that stimulation of nNOS leads to increased activity of calcium-activated potassium (BK(Ca)) channels in these cells. Furthermore, overexpression of nNOS protein in HCASMC greatly enhanced BK(Ca) channel activity. Immunoblot studies demonstrated that E(2) enhances Akt phosphorylation in HCASMC and that wortmannin, an inhibitor of PI3-kinase, attenuated E(2)-stimulated channel activity, NO production, Akt phosphorylation, and estrogen-stimulated coronary relaxation. These studies implicate the PI3-kinase/Akt signaling axis as an estrogen transduction component in vascular smooth muscle cells. We conclude, therefore, that estrogen opens BK(Ca) channels in HCASMC by stimulating nNOS via a transduction sequence involving PI3-kinase and Akt. These findings now provide a molecular mechanism that can explain the clinical observation that estrogen enhances coronary blood flow in patients with diseased or damaged coronary arteries.

Dobutamine stress echocardiography for the detection of coronary artery disease in women

Dobutamine stress echocardiography (DSE) has good diagnostic accuracy for the diagnosis of coronary artery disease (CAD). However, in most published diagnostic studies, patients are predominantly men. In women, diagnostic accuracy may be lower because of a lower prevalence and extent of CAD, a higher incidence of dobutamine stress-induced hypotension (resulting in less stress or even nondiagnostic test results), smaller left ventricular chamber size, and the beneficial effects of estrogens on the induction of myocardial ischemia. To determine the diagnostic accuracy of DSE in women, 14 diagnostic studies published through 2006 were identified through a Medline search. For a total of 901 patients, the weighted mean sensitivity and specificity were 72% and 88%, respectively. In 7 studies directly comparing results in women and men, conflicting results were reported. However, pooled data showed nearly identical values for sensitivity and specificity in women and men. Additionally, in 6 studies directly comparing DSE results in women with those of stress nuclear scintigraphy, DSE was as sensitive and more specific to detect CAD (90% vs 70%, p <0.0001). The excellent specificity of DSE in women was also confirmed by excellent normalcy rates, ranging from 92% to 100% in women, with a <5% pretest probability of CAD. In conclusion, despite some theoretical limitations, DSE has reasonable sensitivity and excellent specificity for the detection of CAD in women. Considering the diagnostic problems of exercise electrocardiography and nuclear scintigraphy in women, stress echocardiography may be the stress modality of choice in women because of its superior diagnostic specificity.