Hormone therapy and antioxidant vitamins do not improve endothelial vasodilator function in postmenopausal women with established coronary artery disease: a substudy of the Women's Angiographic Vitamin and Estrogen (WAVE) trial

The benefits and risks of menopause hormone therapy for the cardiovascular system in postmenopausal women: a systematic review and meta-analysis

BACKGROUND

Menopause hormone therapy (MHT), as an effective method to alleviate the menopause-related symptoms of women, its benefits, risks, and potential influencing factors for the cardiovascular system of postmenopausal women are not very clear.

OBJECTIVES

To evaluate cardiovascular benefits and risks of MHT in postmenopausal women, and analyze the underlying factors that affect both.

SEARCH STRATEGY

The EMBASE, MEDLINE, and CENTRAL databases were searched from 1975 to July 2022.

SELECTION CRITERIA

Randomized Clinical Trials (RCTs) that met pre-specified inclusion criteria were included.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data independently. A meta-analysis of random effects was used to analyze data.

MAIN RESULTS

This systematic review identified 33 RCTs using MHT involving 44,639 postmenopausal women with a mean age of 60.3 (range 48 to 72 years). There was no significant difference between MHT and placebo (or no treatment) in all-cause death (RR = 0.96, 95%CI 0.85 to 1.09, I2 = 14%) and cardiovascular events (RR = 0.97, 95%CI 0.82 to 1.14, I2 = 38%) in the overall population of postmenopausal women. However, MHT would increase the risk of stroke (RR = 1.23, 95%CI 1.08 to 1.41,I2 = 0%) and venous thromboembolism (RR = 1.86, 95%CI 1.39 to 2.50, I2 = 24%). Compared with placebo, MHT could improve flow-mediated arterial dilation (FMD) (SMD = 1.46, 95%CI 0.86 to 2.07, I2 = 90%), but it did not improve nitroglycerin-mediated arterial dilation (NMD) (SMD = 0.27, 95%CI - 0.08 to 0.62, I2 = 76%). Compared with women started MHT more than 10 years after menopause, women started MHT within 10 years after menopause had lower frequency of all-cause death (P = 0.02) and cardiovascular events (P = 0.002), and more significant improvement in FMD (P = 0.0003). Compared to mono-estrogen therapy, the combination therapy of estrogen and progesterone would not alter the outcomes of endpoint event. (all-cause death P = 0.52, cardiovascular events P = 0.90, stroke P = 0.85, venous thromboembolism P = 0.33, FMD P = 0.46, NMD P = 0.27).

CONCLUSIONS

MHT improves flow-mediated arterial dilation (FMD) but fails to lower the risk of all-cause death and cardiovascular events, and increases the risk of stroke and venous thrombosis in postmenopausal women. Early acceptance of MHT not only reduces the risk of all-cause death and cardiovascular events but also further improves FMD, although the risk of stroke and venous thrombosis is not reduced. There is no difference in the outcome of cardiovascular system endpoints between mono-estrogen therapy and combination therapy of estrogen and progesterone.

Estrogen and the Vascular Endothelium: The Unanswered Questions

Premenopausal women have a lower incidence of cardiovascular disease (CVD) compared with their age-matched male counterparts; however, this discrepancy is abolished following the transition to menopause or during low estrogen states. This, combined with a large amount of basic and preclinical data indicating that estrogen is vasculoprotective, supports the concept that hormone therapy could improve cardiovascular health. However, clinical outcomes in individuals undergoing estrogen treatment have been highly variable, challenging the current paradigm regarding the role of estrogen in the fight against heart disease. Increased risk for CVD correlates with long-term oral contraceptive use, hormone replacement therapy in older, postmenopausal cisgender females, and gender affirmation treatment for transgender females. Vascular endothelial dysfunction serves as a nidus for the development of many cardiovascular diseases and is highly predictive of future CVD risk. Despite preclinical studies indicating that estrogen promotes a quiescent, functional endothelium, it still remains unclear why these observations do not translate to improved CVD outcomes. The goal of this review is to explore our current understanding of the effect of estrogen on the vasculature, with a focus on endothelial health. Following a discussion regarding the influence of estrogen on large and small artery function, critical knowledge gaps are identified. Finally, novel mechanisms and hypotheses are presented that may explain the lack of cardiovascular benefit in unique patient populations.

Roles of Oxidative Stress and Inflammation in Vascular Endothelial Dysfunction-Related Disease

Oxidative stress and chronic inflammation play an important role in the pathogenesis of atherosclerosis. Atherosclerosis develops as the first step of vascular endothelial dysfunction induced by complex molecular mechanisms. Vascular endothelial dysfunction leads to oxidative stress and inflammation of vessel walls, which in turn enhances vascular endothelial dysfunction. Vascular endothelial dysfunction and vascular wall oxidative stress and chronic inflammation make a vicious cycle that leads to the development of atherosclerosis. Simultaneously capturing and accurately evaluating the association of vascular endothelial function with oxidative stress and inflammation would be useful for elucidating the pathophysiology of atherosclerosis, determining treatment efficacy, and predicting future cardiovascular complications. Intervention in both areas is expected to inhibit the progression of atherosclerosis and prevent cardiovascular complications.

Body composition and cardiometabolic health across the menopause transition

Every year, 2 million women reach menopause in the United States, and they may spend 40% or more of their life in a postmenopausal state. In the years immediately preceding menopause-known as the menopause transition (or perimenopause)-changes in hormones and body composition increase a woman's overall cardiometabolic risk. In this narrative review, we summarize the changes in weight, body composition, and body fat distribution, as well as the changes in energy intake, energy expenditure, and other cardiometabolic risk factors (lipid profile, glucose metabolism, sleep health, and vascular function), that occur during the menopause transition. We also discuss the benefits of lifestyle interventions in women in the earlier stages of menopause before these detrimental changes occur. Finally, we discuss how to include perimenopausal women in research studies so that women across the life-span are adequately represented.

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Aging under Pressure: The Roles of Reactive Oxygen and Nitrogen Species (RONS) Production and Aging Skeletal Muscle in Endothelial Function and Hypertension-From Biological Processes to Potential Interventions

The proportion of adults living with hypertension increases significantly with advancing age. It is therefore important to consider how health and vitality can be maintained by the aging population until end of life. A primary risk factor for the progression of cardiovascular diseases (CVD) is hypertension, so exploring the factors and processes central to this burden of disease is essential for healthy aging. A loss of skeletal muscle quantity and quality is characteristic in normal aging, with a reduction of vasodilatory capacity caused by endothelial dysfunction, and subsequent increase in peripheral resistance and risk for hypertension. Reactive Oxygen and Nitrogen Species (RONS) encompass the reactive derivatives of NO and superoxide, which are continuously generated in contracting skeletal muscle and are essential mediators for cellular metabolism. They act together as intra and intercellular messengers, gene expression regulators, and induce programmed cell death. In excessive amounts RONS can inflict damage to endothelial and skeletal muscle cells, alter signaling pathways or prematurely promote stress responses and potentially speed up the aging process. The age-related increase in RONS by skeletal muscle and endothelial mitochondria leads to impaired production of NO, resulting in vascular changes and endothelial dysfunction. Changes in vascular morphology is an early occurrence in the etiology of CVDs and, while this is also a normal characteristic of aging, whether it is a cause or a consequence of aging in hypertension remains unclear. This review serves to focus on the roles and mechanisms of biological processes central to hypertension and CVD, with a specific focus on the effects of aging muscle and RONS production, as well as the influence of established and more novel interventions to mediate the increasing risk for hypertension and CVD and improve health outcomes as we age.

Particulate matter air pollutants and cardiovascular disease: Strategies for intervention

Air pollution is consistently linked with elevations in cardiovascular disease (CVD) and CVD-related mortality. Particulate matter (PM) is a critical factor in air pollution-associated CVD. PM forms in the air during the combustion of fuels as solid particles and liquid droplets and the sources of airborne PM range from dust and dirt to soot and smoke. The health impacts of PM inhalation are well documented. In the US, where CVD is already the leading cause of death, it is estimated that PM2.5 (PM < 2.5 μm in size) is responsible for nearly 200,000 premature deaths annually. Despite the public health data, definitive mechanisms underlying PM-associated CVD are elusive. However, evidence to-date implicates mechanisms involving oxidative stress, inflammation, metabolic dysfunction and dyslipidemia, contributing to vascular dysfunction and atherosclerosis, along with autonomic dysfunction and hypertension. For the benefit of susceptible individuals and individuals who live in areas where PM levels exceed the National Ambient Air Quality Standard, interventional strategies for mitigating PM-associated CVD are necessary. This review will highlight current state of knowledge with respect to mechanisms for PM-dependent CVD. Based upon these mechanisms, strategies for intervention will be outlined. Citing data from animal models and human subjects, these highlighted strategies include: 1) antioxidants, such as vitamins E and C, carnosine, sulforaphane and resveratrol, to reduce oxidative stress and systemic inflammation; 2) omega-3 fatty acids, to inhibit inflammation and autonomic dysfunction; 3) statins, to decrease cholesterol accumulation and inflammation; 4) melatonin, to regulate the immune-pineal axis and 5) metformin, to address PM-associated metabolic dysfunction. Each of these will be discussed with respect to its potential role in limiting PM-associated CVD.

Unraveling mechanisms of toxicant-induced oxidative stress in cardiovascular disease

To date, numerous clinical studies examining correlations between oxidative stress biomarkers and cardiovascular diseases (CVD) have repeatedly suggested a role for oxidant injury in the pathogenesis of diseases such as atherosclerosis. Despite this, antioxidant supplementation trials have not demonstrated a reduction in disease progression. Nevertheless, small animal and epidemiological studies have linked exposures to certain toxicants with increased CVD risk involving putative oxidative stress mechanisms. A few prototypical vascular toxicants will be discussed as examples of toxicants that likely act via oxidative stress mechanisms. For discussion, we will classify these toxicants as those that induce direct (e.g., arsenic, nucleoside reverse transcriptase inhibitors) versus indirect (particulate matter, ozone) oxidative stress mechanisms, and those that likely induce CVD through both direct and indirect mechanisms (cigarette smoke). Finally, new findings in oxidative stress research, including the emerging importance of reactive sulfur species, hydrogen peroxide as a presumed endothelium-derived hyperpolarizing factors, etc., will be discussed, as well as the need to determine the role of toxicants in modulating these newly identified pathways. Moreover, given the lack of success in conclusively demonstrating the roles of oxidative stress in CVD risk stratification, research probing the roles of toxicant exposures in propagating CVD pathogenesis may be a novel approach for more conclusively delineating the causal role of oxidative stress in CVD initiation and progression.

Metabolic Syndrome and Menopause: Pathophysiology, Clinical and Diagnostic Significance

Menopause is a risk factor for cardiometabolic diseases, including metabolic syndrome (MetS), type 2 diabetes, and cardiovascular diseases. MetS is a constellation of interdependent factors such as insulin resistance, abdominal obesity, dyslipidemia, and hypertension. The prevalence of MetS in postmenopause is due to loss of the protective role of estrogens and increased circulating androgens resulting in changes to body fat distribution and development of abdominal obesity. Excessive visceral adipose tissue plays an important role due to synthesis and secretion of bioactive substances such as adipocytokines, proinflammatory cytokines, reactive oxygen species, prothrombotic, and vasoconstrictor factors. MetS may also impact risk assessment of breast cancer, osteoporosis and chronic kidney disease, and quality of life during the menopausal transition. Increased MetS has stimulated the exploration of new laboratory tests for early detection and therapies.

The effect of hormone therapy on biochemical and ultrasound parameters associated with atherosclerosis in 46,XY DSD individuals with female phenotype

The aim of this study was to evaluate the effect of hormone therapy (HT) in the endothelial function of 46,XY disorders of sexual development (DSD) patients with female phenotype. Biochemical and ultrasound measurements were performed in 20 patients at initiation of oral 2 mg 17β-estradiol/1 mg norethisterone acetate, and after 6 months of therapy. Lipid profile, including total cholesterol (TC), LDL, HDL, triglycerides (TG) and Atherogenic Index of Plasma (AIP), as well as levels of VE-Cadherin, E-Selectin, Thrombomodulin and vWf were determined. Ultrasonographic examinations included evaluation of flow-mediated dilatation (FMD) and measurement of Carotid and Femoral Intima Media Thickness (IMT). HT raised HDL (35.4 mg/dl versus 40.1 mg/dl, p = 0.019) while lowering TG (166 mg/dl versus 109 mg/dl, p = 0.026) and AIP (0.24 versus 0.04, p = 0.007). No changes were noted in TC and LDL (215.7 mg/dl versus 192.25 mg/dl and 87.46 mg/dl versus 76.35 mg/dl, respectively). There was significant reduction of VE-Cadherin (4.05 ng/ml versus 2.20 ng/ml, p = 0.002) and E-selectin (73.98 ng/ml versus 56.73 ng/ml, p = 0.004). No change was observed in Thrombomodulin and vWf (11.76 ng/ml versus 13.90 ng/ml and 80.75% versus 79.55%, respectively). FMD improved significantly (5.4% versus 8.15%, p = 0.003), while only carotid bulb IMT decreased significantly (0.65 mm versus 0.60 mm, p = 0.018). Overall, HT was found to improve biochemical and ultrasound markers of endothelial function in 46,XY DSD patients with female phenotype.

Intermediate end point cardiovascular clinical trials: an excellent idea based on an obsolete paradigm

Intermediate end points are widely used in cardiovascular clinical trials mainly to forecast/foreshadow actual clinical cardiovascular outcomes. This approach is based on the historical atherosclerosis paradigm which states in part that the effects of traditional cardiovascular risk factors on clinical cardiovascular disease (CVD) events are solely mediated through subclinical cardiovascular disease/atherosclerosis. The utility of intermediate end point CVD clinical trials using either historical subclinical CVD markers such as quantitative angiography or current sophisticated markers such as coronary artery calcium, carotid intima-media thickness or brachial flow mediated dilation has been variable. Discoveries of other pathways pertinent to the pathogenesis of atherosclerosis calls for a new conceptual model or paradigm and helps explain the discordance in results from prior and ongoing intermediate end point-clinical CVD event trial pairs.

Hypertension in postmenopausal women

Blood pressure is typically lower in premenopausal women than in men. However, after menopause, the prevalence of hypertension in women is higher than it is in men. Hypertension is a major risk factor for cardiovascular disease in women and men, but cardiovascular disease is the leading cause of death in women. Furthermore, there is evidence that blood pressure may not be as well-controlled in women as in men, despite the fact that most women adhere better to their therapeutic regimens and medications than do men, and have their blood pressures measured more frequently than do men. This review describes possible mechanisms by which blood pressure may be increased in postmenopausal women.

Vascular effects and safety of dalcetrapib in patients with or at risk of coronary heart disease: the dal-VESSEL randomized clinical trial

AIMS

High-density lipoprotein cholesterol (HDL-C) is inversely associated with cardiovascular (CV) events and thus an attractive therapeutic target. However, in spite of marked elevations in HDL-C, the first cholesterol transport protein (CETP) inhibitor torcetrapib raised blood pressure (BP), impaired endothelial function, and increased CV mortality and morbidity. Dalcetrapib is a novel molecule acting on CETP with a different chemical structure to torcetrapib. As HDL stimulates nitric oxide (NO), suppresses inflammation, and exerts protective CV effects, we investigated the effects of dalcetrapib on endothelial function, blood pressure, inflammatory markers, and lipids in patients with, or at risk of, coronary heart disease (CHD) in a double-blind randomized placebo-controlled trial (clinicaltrials.gov number NCT00655538).

METHODS AND RESULTS

Patients with target low-density lipoprotein cholesterol (LDL-C) levels received dalcetrapib 600 mg/day or placebo for 36 weeks on top of standard therapy (including statins). The primary outcome measures were the change from baseline of flow-mediated dilatation (%FMD) of the right brachial artery after 5 min of cuff occlusion at 12 weeks and the 24 h ambulatory blood pressure monitoring (ABPM) at week 4. Secondary outcomes included change from baseline in FMD after 36 weeks and the change in ABPM at 12 and 36 weeks, changes in HDL-C, LDL-C, triglycerides, CETP activity, as well as standard safety parameters. Four hundred seventy-six patients were randomized. Baseline FMD was 4.1 ± 2.2 and 4.0 ± 2.4% with placebo or dalcetrapib, respectively and did not change significantly from placebo after 12 and 36 weeks (P = 0.1764 and 0.9515, respectively). After 4, 24, and 36 weeks of treatment with dalcetrapib, CETP activity decreased by 51, 53, and 56% (placebo corrected, all P < 0.0001), while at weeks 4, 12, and 36 HDL-C increased by 25, 27, and 31% (placebo corrected, all P < 0.0001). Low-density lipoprotein cholesterol levels did not change. At baseline, ABPM was 125 ± 12/74 ± 8mmHg in the placebo and 128 ± 11/75 ± 7mmHg in the dalcetrapib group (P = 0.3372 and 0.1248, respectively, placebo-corrected change from baseline) and did not change for up to 36 weeks. Biomarkers of inflammation, oxidative stress, and coagulation did not change during follow-up except for Lp-PLA(2) mass levels which increased by 17% (placebo corrected). Overall 7 patients given dalcetrapib and 8 patients given placebo experienced at least one pre-specified adjudicated event (11 events with dalcetrapib and 12 events with placebo).

CONCLUSION

The dal-VESSEL trial has established the tolerability and safety of CETP-inhibition with dalcetrapib in patients with or at risk of CHD. Dalcetrapib reduced CETP activity and increased HDL-C levels without affecting NO-dependent endothelial function, blood pressure, or markers of inflammation and oxidative stress. The dal-OUTCOMES trial (NCT00658515) will show whether dalcetrapib improves outcomes in spite of a lack of effect on endothelial function.

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.

Postmenopausal hypertension

Cardiovascular disease is the leading cause of morbidity and mortality in postmenopausal women. Hypertension is a major risk factor for cardiovascular disease. The mechanisms responsible for postmenopausal hypertension have not been completely elucidated. However, various mechanisms have been implicated to play a role. For example, there is evidence that changes in estrogen/androgen ratios favoring increases in androgens, activation of the renin-angiotensin and endothelin systems, activation of the sympathetic nervous system, metabolic syndrome and obesity, inflammation, increased vasoconstrictor eicosanoids, and anxiety and depression may be important in the pathogenesis of postmenopausal hypertension. There is also evidence that hypertension is less well controlled in aging women than in aging men, but the reasons for this gender difference is not clear. Postmenopausal hypertension is likely multifactorial. Future studies will be necessary to determine the contribution of these systems listed above in mediating postmenopausal hypertension and to design treatment strategies that encompass these mechanisms to improve the quality of life of postmenopausal women as they age.

Aging and vascular endothelial function in humans

Advancing age is the major risk factor for the development of CVD (cardiovascular diseases). This is attributable, in part, to the development of vascular endothelial dysfunction, as indicated by reduced peripheral artery EDD (endothelium-dependent dilation) in response to chemical [typically ACh (acetylcholine)] or mechanical (intravascular shear) stimuli. Reduced bioavailability of the endothelium-synthesized dilating molecule NO (nitric oxide) as a result of oxidative stress is the key mechanism mediating reduced EDD with aging. Vascular oxidative stress increases with age as a consequence of greater production of reactive oxygen species (e.g. superoxide) without a compensatory increase in antioxidant defences. Sources of increased superoxide production include up-regulation of the oxidant enzyme NADPH oxidase, uncoupling of the normally NO-producing enzyme, eNOS (endothelial NO synthase) (due to reduced availability of the cofactor tetrahydrobiopterin) and increased mitochondrial synthesis during oxidative phosphorylation. Increased bioactivity of the potent endothelial-derived constricting factor ET-1 (endothelin-1), reduced endothelial production of/responsiveness to dilatory prostaglandins, the development of vascular inflammation, formation of AGEs (advanced glycation end-products), an increased rate of endothelial apoptosis and reduced expression of oestrogen receptor α (in postmenopausal females) also probably contribute to impaired EDD with aging. Several lifestyle and biological factors modulate vascular endothelial function with aging, including regular aerobic exercise, dietary factors (e.g. processed compared with non-processed foods), body weight/fatness, vitamin D status, menopause/oestrogen deficiency and a number of conventional and non-conventional risk factors for CVD. Given the number of older adults now and in the future, more information is needed on effective strategies for the prevention and treatment of vascular endothelial aging.

Smoking and atherosclerotic cardiovascular disease: part II: role of cigarette smoking in cardiovascular disease development

Potential mechanisms and biomarkers of atherosclerosis related to cigarette smoking - a modifiable risk factor for that disease - are discussed in this article. These include smoking-associated inflammatory markers, such as leukocytes, high-sensitivity C-reactive protein, serum amyloid A, ICAM-1 and IL-6. Other reviewed markers are indicative for smoking-related impairment of arterial endothelial function (transcapillary leakage of albumin, inhibition of endogenous nitric oxide synthase activity and reduced endothelium-dependent vasodilation) or point to oxidative stress caused by various chemicals (cholesterol oxidation, autoantibodies to oxidized low-density lipoprotein, plasma levels of malondialdehyde and F(2)-isoprostanes and reduced antioxidant capacity). Smoking enhances platelet aggregability, increases blood viscosity and shifts the pro- and antithrombotic balance towards increased coagulability (e.g., fibrinogen, von Willebrand factor, ICAM-1 and P-selectin). Insulin resistance is higher in smokers compared with nonsmokers, and hemoglobin A1c is dose-dependently elevated, as is homocysteine. Smoke exposure may influence the kinetics of markers with different response to transient or chronic changes in cigarette smoking behavior.

Characterization of an animal model of postmenopausal cardiac hypertrophy and novel mechanisms responsible for cardiac decompensation using ovariectomized pressure-overloaded rats

OBJECTIVE

The development of animal models of cardiovascular disease are critical to define pathophysiological mechanisms and to advance diagnosis and therapy. The lack of a suitable animal model represents a failure to define the mechanisms responsible for postmenopausal myocardial hypertrophy in hypertension and adverse cardiac remodeling.

METHODS

In this review, we presented a rat model of postmenopausal myocardial hypertrophy, with particular focus on the similarities between the animal model and postmenopausal women regarding myocardial function as well as molecular and subcellular mechanisms. To elucidate the molecular mechanism of left ventricular (LV) hypertrophy and remodeling in postmenopausal women, we analyzed myocardial hypertrophy as well as cardiac function and hypertrophy-related protein expression in ovariectomized (OVX) and pressure overloaded (PO) rats.

RESULTS

The model is characterized by depletion of serum estrogen and increased heart-to-body weight and lung-to-body weight ratios. Moreover, the OVX-PO rats also show increased mean arterial blood pressure, LV end-diastolic pressure, LV developed pressure, and maximal rates of LV contraction and relaxation compared with the OVX group. Importantly, Akt activity was largely attenuated, and both endothelial nitric oxide synthase expression and activity were markedly reduced in the OVX-PO group. Finally, significant increased mortality was observed in the OVX-PO group after chronic isoproterenol administration.

CONCLUSIONS

Our results demonstrate that rats subject to OVX are unable to compensate for hypertrophy partly due to impaired Akt-endothelial nitric oxide synthase signaling along with deteriorated heart function and demonstrated increased mortality. In this review, we discussed the mechanisms of cardiac injury, which could play a critical role in postmenopausal hypertrophy, as well as the characteristics of the OVX-PO female rats as a model to test cardioprotective drugs in postmenopausal women.

Effects of hormone therapy on soluble cell adhesion molecules in postmenopausal women with coronary artery disease

OBJECTIVE

Although observational studies showed an apparent lower ischemic coronary disease risk in postmenopausal women receiving hormone therapy (HT), randomized clinical trials in postmenopausal women showed an increase in ischemic cardiovascular events. Soluble cell adhesion molecules have been associated with cardiovascular risk factors and events. HT reduces circulating levels of soluble cell adhesion molecules in healthy postmenopausal women, but its effects in postmenopausal women with coronary artery disease are less clear. We assessed the effect of HT on soluble cell adhesion molecules in the Estrogen Replacement and Atherosclerosis trial.

DESIGN

The Estrogen Replacement and Atherosclerosis trial was a double-blind, placebo-controlled study that randomized 309 postmenopausal women (mean age, 65.8 y) to daily unopposed estrogen (conjugated estrogens 0.625 mg), estrogen plus 2.5 mg of medroxyprogesterone acetate, or placebo, with a mean follow-up period of 3.2 years. Soluble intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin were measured in serum obtained from participants at baseline and after 12 months of follow-up.

RESULTS

Of the 265 women with complete data, 87 women were assigned to unopposed estrogen, 88 women to estrogen plus medroxyprogesterone acetate, and 90 women to placebo. Compared with placebo, 12 months of HT (n = 175) was associated with reductions in soluble intercellular adhesion molecule-1 (25.6 +/- 4.7 vs 10.6 +/- 6.4 ng/mL, P = 0.06), soluble vascular cell adhesion molecule-1 (80.2+/- 10.6 vs 28.8 +/- 14.7 ng/mL, P = 0.005), and E-selectin (8.8 +/- 0.9 vs -1.1 +/- 1.2 ng/mL, P < 0.001).

CONCLUSIONS

Twelve months of HT in postmenopausal women with established coronary artery disease was associated with reductions in serum markers of endothelial cell activation/injury such as soluble intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin.

Sex differences in control of blood pressure: role of oxidative stress in hypertension in females

In general, blood pressure is higher in normotensive men than in age-matched women, and the prevalence of hypertension in men is also higher until after menopause, when the prevalence of hypertension increases for women. It is likely then that the mechanisms by which blood pressure increases in men and women with aging may be different. Although clinical trials to reduce blood pressure with antioxidants have typically not been successful in human cohorts, studies in male rats suggest that oxidative stress plays an important role in mediating hypertension. The exact mechanisms by which oxidative stress increases blood pressure have not been completely elucidated. There may be several reasons for the discrepancies between clinical and animal studies. In this review, the data obtained in selected clinical and animal studies are discussed, and the hypothesis is put forward that oxidative stress may not be as important in mediating hypertension in females as has been shown previously in male rats. Furthermore, it is likely that differences in genetics, age, length of time with hypertension, endothelial dysfunction, and sex are all factored in to modulate the responses to antioxidants in humans. As such, future clinical trials should be designed and powered to evaluate the effects of oxidative stress on blood pressure separately in men and women.

Combined continuous ethinyl estradiol/norethindrone acetate does not improve forearm blood flow in postmenopausal women at risk for cardiovascular events: a pilot study

OBJECTIVE

This study sought to determine whether combined continuous ethinyl estradiol and norethindrone acetate, a postmenopausal hormone therapy (HT) combination designed to have fewer side effects than cyclical therapies and therapies using medroxyprogesterone acetate (MPA), could improve vascular endothelial function in postmenopausal women with risk factors for cardiovascular disease (CVD).

METHODS

Eighteen postmenopausal women (mean age 62 +/- 11 years) participated in a randomized, placebo-controlled, crossover design trial of 10 microg estradiol/1 mg norethindrone acetate given once daily for 3 months, with a 1-month washout period between placebo and active treatment phases. Vascular reactivity was assessed at each phase of the study using high-frequency brachial artery ultrasound in response to flow-mediated hyperemia, cold pressor testing, and sublingual nitroglycerin. Markers of cardiovascular risk, including cholesterol levels, inflammatory markers, fibrinolytic markers, and solubilized adhesion molecules, were also measured at each phase.

RESULTS

We found no significant difference in vascular reactivity measurements during active treatment with ethinyl estradiol/norethindrone acetate vs. placebo. C-reactive protein (CRP) levels increased significantly during active treatment, and high-density lipoprotein (HDL) levels decreased significantly. Vascular cell adhesion molecule-1 (VCAM-1) levels declined during active treatment. Plasminogen activator inhibitor-1 (PAI-1) levels were inversely correlated with flow-mediated hyperemic vascular reactivity, independent of active treatment or placebo phases.

CONCLUSIONS

In this older postmenopausal population with at least one cardiovascular risk factor, treatment with combined continuous ethinyl estradiol and norethindrone acetate failed to improve vascular endothelial function. The agent's proinflammatory effect or subclinical atherosclerosis in this population may have contributed to this finding.

SEX DIFFERENCES IN OXIDATIVE STRESS AND THE IMPACT ON BLOOD PRESSURE CONTROL AND CARDIOVASCULAR DISEASE

1. In the present review, we addressed studies in humans and rats to determine the role that oxidative stress may play in mediating cardiovascular outcomes. 2. Biochemical evaluation of oxidative stress in both humans and spontaneously hypertensive rats gives equivocal results as to the relative levels in males versus females. Clinical trials with anti-oxidants in humans have not shown consistent results in protecting against detrimental cardiovascular outcomes. In spontaneously hypertensive rats (SHR), blockade studies using tempol or apocynin reduce renal oxidative stress and blood pressure in male SHR, but not in female rats. In addition, increasing oxidative stress with molsidomine increases blood pressure in male, but not female, SHR. Treatment with vitamins E and C reduces blood pressure in young male, but not aged, animals. Furthermore tempol is unable to reduce blood pressure in young male SHR in the absence of a functional nitric oxide system. 3. Neither human nor animal studies are consistent in terms of whether oxidative stress levels are higher in males or females. Furthermore, anti-oxidant therapy in humans often does not ameliorate, or even attenuate, the negative cardiovascular consequences of increased oxidative stress. Our studies in SHR shed light on why these outcomes occur.

The effect of diet on endothelial function

Endothelial dysfunction is an early precursor to atherosclerosis. Lifestyle interventions, including diet, have been shown to affect endothelial function. High-fat diets have been shown to impair endothelial function, and diets such as the Mediterranean diet have been associated with improved endothelial function. This review discusses the effects of diet, dietary supplements such as folic acid, polyphenols, and antioxidant vitamins on endothelial function. We provide a summary of the current data linking diet with endothelial function and explore controversies within this field.

[Endocrine disorders and the heart]

Hormonal regulation is not possible without the cardiovascular system, and thus the heart plays a special role not only in the action and synthesis, but also in the distribution of hormones. Severe endocrine disorders with cardiac involvement are often threatening for the patient. The impact of aberrant thyroid function, the sympathetic-adrenal symptoms of which predominantly affect the heart, is well known. Diabetes mellitus and the associated metabolic syndrome are major causes of cardiovascular disease and determine its morbidity and lethality rates. Acromegaly causes a complex cardiomyopathy that may result in cardiac failure refractive to conventional treatment. The excessive production of adrenal hormones in Cushing's syndrome, hyperaldosteronism and pheochromocytoma primarily harms the heart by causing severe hypertension. The same holds true for long-standing hyperparathyroidism. Recent prospective studies did not confirm the protective effect of hormone replacement therapy on cardiovascular disease.

Effects of estrogen replacement with and without medroxyprogesterone acetate on brachial flow-mediated vasodilator responses in postmenopausal women with coronary artery disease

BACKGROUND

Hormone therapy has been shown to have no cardioprotective effect and may, in fact, be harmful in older postmenopausal women. Estrogen has been shown to enhance endothelial-dependent flow-mediated vasodilation (FMD) in healthy and younger women. The effect of estrogen on older and less healthy postmenopausal women with atherosclerosis is unclear.

METHODS

The Estrogen Replacement and Atherosclerosis trial randomized 309 postmenopausal women with established coronary atherosclerosis (mean, 65.8 years) to unopposed estrogen (conjugated estrogen, 0.625 mg), estrogen plus 2.5 mg medroxyprogesterone actate (MPA), or placebo. After mean of 3.2 years of follow-up, brachial FMD was measured using 2-dimensional ultrasound in women available for follow-up at 4 of the 5 clinic sites (n = 198).

RESULTS

The %FMD of the brachial artery was not statistically different in the placebo arm compared with either unopposed estrogen or estrogen + MPA arm in both the adjusted and the unadjusted models. Subsequent analysis combining the estrogen arm with the estrogen + MPA arm and comparing with the placebo arm was also not significant in both the adjusted and the unadjusted models. Similar results were obtained when analyses were limited to women who took >80% of the study medication over the course of the trial (n = 133).

CONCLUSION

An average of 3.2 years of treatment with unopposed estrogen or estrogen plus progestins did not result in significant improvements in endothelial vasodilation compared with placebo. This apparent absence of an effect on brachial artery endothelial function in older postmenopausal women with established coronary heart disease may help explain the lack of benefit of estrogen for secondary prevention of coronary heart disease.

Retention of ovaries and oxidative stress of surgery

OBJECTIVE

Surgical menopause results in severe menopausal symptoms due to the sudden withdrawal of estrogen. This study evaluated the impact of surgical menopause on oxidant and antioxidant status.

METHODS

Thirty eight women who underwent total hysterectomy with or without bilateral salpingo-oophorectomy were included. Oxidant status was assessed by measuring plasma levels of malondialdehyde (MDA) and antioxidant status by assessing glutathione (GSH) and estrogen levels.

RESULTS

The levels of MDA were increased in all women, and GSH levels were significantly decreased in women who underwent hysterectomy alone but significantly increased in those who also had oophorectomy. Estrogen levels were increased if the ovaries were retained even in postmenopausal women, while they were decreased in the women who underwent oophorectomy.

CONCLUSION

Oxidative stress of surgery, as assessed by increased MDA levels, occurred in all women. After oophorectomy, estrogen levels decreased and GSH levels increased in both premenopausal and postmenopausal women. The ovaries may therefore respond to oxidative stress of surgery by increasing estrogen production, estrogen being a better antioxidant than GSH.

Micronutrients and their supplementation in chronic cardiac failure. An update beyond theoretical perspectives

Physicians' use of micronutrients to improve symptoms or outcomes in chronic illness has until recently been guided by limited data on the actions of individual agents in vitro or in animal studies. However several recently published clinical trials have provided information about which groups of patients are likely to benefit from which combination of micronutrients. Patients with chronic cardiac failure (CCF), particularly elderly individuals, have several reasons to be deficient in micronutrients including reduced intake, impaired gastrointestinal absorption and increased losses on the background of increased utilisation due for example to increased oxidative stress. Studies of nutritional supplementation in CCF patients have usually concentrated on specific agents. However given that many micronutrients have synergistic influences upon metabolic processes this strategy might merely lead to a shifting of a limiting step. Rather, a strategy of increasing the availability of multiple agents at once might be more logical. The aim of this article is to briefly review the experimental rationale for each of the micronutrients of potential benefit in chronic heart failure and examine the current clinical trial evidence supporting their use.

Tratamiento hormonal sustitutivo y enfermedades cardiovasculares

Despite biologically plausible mechanisms for cardiac protection and compelling evidence from observational studies suggesting that menopausal hormone therapy confers cardiovascular benefit, results of well-designed and conducted randomized clinical trials in healthy women and in women with established coronary heart disease displayed that menopausal hormone therapy failed to prevent clinical cardiovascular events and rather was associated with harms. Clinical trial of the SERM raloxifene also did not demonstrate a decrease in coronary events. It is unknown whether the earlier initiation of such therapies, i.e., at menopause, would result in favorable outcomes; or whether different hormonal preparations, lower doses, or alternate routes of administration would confer benefit. At present, proved coronary risk reduction strategies are requisite (albeit underutilized) for menopausal women; these include lifestyle and pharmacologic coronary preventive interventions. The baseline characteristics of menopausal women with coronary heart disease who were participants in cardiovascular outcome trials of menopausal hormone therapy or raloxifene were remarkably similar; globally, cardiovascular risk factors were not optimally controlled at entry into these trials, suggesting that more aggressive cardiovascular risk interventions are appropriate to achieve optimal target goals for menopausal women with documented coronary heart disease.

Estrogen and hypertension

Menopause is accompanied by a dramatic rise in the prevalence of hypertension in women, suggesting a protective role of endogenous estradiol on blood pressure (BP). Both animal experimental and human clinical investigations suggest that estrogen engages several mechanisms that protect against hypertension, such as activation of the vasodilator pathway mediated by nitric oxide and prostacyclin and inhibition of the vasoconstrictor pathway mediated by the sympathetic nervous system and angiotensin. However, emerging evidence from recent clinical trials indicates a small increase, rather than decrease, in systolic BP with oral estrogen administration in postmenopausal women, without any detectable effect on diastolic BP. Mechanisms underlying this selective rise in systolic BP in postmenopausal women and oral contraceptive-induced hypertension in premenopausal women remain unknown, but the rise may be related to supraphysiologic concentration of estrogen in the liver. To date, transdermal delivery of estrogen, which avoids the first-pass hepatic metabolism of estradiol, appears to have a small BP-lowering effect in postmenopausal women and may be a safer alternative in hypertensive women.

Assessing drug risks and benefits: lessons from postmenopausal hormone therapy studies

The issue of safety standards for new drugs remains unsettled. Limitations of biomarker or observational studies for assessing global safety and efficacy of postmenopausal hormone therapy are highlighted by contrast with randomized clinical trial results. On the other hand, requiring large-scale, long-term outcome trials for every new drug might not be practical. Randomized trials with intermediate outcomes such as coronary angiography, coronary or carotid ultrasound, or coronary calcification present attractive alternatives. Trials with intermediate outcomes can be conducted with much smaller sample sizes and shorter duration, but the adequacy of these types of trials for assessment of safety and efficacy remains a topic of ongoing discussion in the scientific and regulatory communities.