Evidence for a role of hot flushes in vascular function in recently postmenopausal women

The relationship between dyslipidemia and menopausal symptoms in Chinese menopausal women: a cross-sectional study

OBJECTIVE

To investigate the relationship of dyslipidemia and menopausal symptoms in Chinese menopausal women.

MATERIAL AND METHODS

A total of 989 eligible participants with menopausal syndrome were recruited from outpatient clinics in several cities in China. Menopausal symptoms were assessed using the Chinese Menopause Rating Scale (CMRS), the Self-rating Depression Scale (SDS), and the Self-rating Anxiety Scale (SAS). Serum lipid profile was measured using enzyme colorimetry. The relationship between lipid profile and menopausal symptoms was assessed using Student's t test/nonparametric Mann-Whitney U test, Spearman's correlation test, and binary logistic regression analysis.

RESULTS

Among the 989 patients, 527 had dyslipidemia while 462 did not. Patients with dyslipidemia had significantly higher Self-rating Anxiety Scale (SAS) scores than those without (p < 0.001), while there was no significant difference in Self-rating Depression Scale (SDS) scores. Patients without dyslipidemia had higher scores on the Chinese Menopause Rating Scale (CMRS) vascular dimension compared to those with dyslipidemia (p = 0.003). The correlation test revealed that variables associated with dyslipidemia included age (p = 0.031), CMRS hot flashes dimension score (P = 0.003), and SAS score (p < 0.001). Regression analysis demonstrated that BMI (OR: 1.08, 95% CI: 1.01-1.16, p = 0.027), SAS scores (OR = 1.10, 95% CI = 1.07-1.13), vasomotor dimension (OR = 0.89, 95% CI = 0.83-0.95), physical dimension (OR = 0.96, 95% CI = 0.93-1.00), and social dimension (OR = 0.84, 95% CI = 0.74-0.95) were independently associated with an increased risk of dyslipidemia.

CONCLUSIONS

This study showed that anxiety was associated with an unfavorable lipid profile, and menopausal depression seemed to have no relationship with lipid profile, while vasomotor symptoms appeared to be a favorable factor for dyslipidemia in Chinese menopausal women.

Vasomotor symptoms and their links to cardiovascular disease risk

Hot flashes and night sweats, also known as vasomotor symptoms (VMS), are common and bothersome symptoms of the menopause transition. In addition to negatively impacting quality of life, VMS have been associated with multiple indicators of cardiovascular disease (CVD) risk, including an unfavorable CVD risk factor profile, increased subclinical CVD, and elevated risk of CVD events. Several facets of VMS have been associated with CVD risk, including the frequency, timing, duration, and severity of VMS. VMS may signify poor or degrading cardiovascular health among midlife women and indicate women who warrant focused CVD prevention efforts.

Vasomotor symptoms of menopause, autonomic dysfunction, and cardiovascular disease

Cardiovascular disease (CVD), the leading cause of death among US adults, is more prevalent in menopausal females compared with age-matched males. Vasomotor symptoms of menopause (VMS; hot flashes/flushes and night sweats) are common among females undergoing menopausal transition and have been associated with elevated blood pressure (BP) and increased CVD risk. Autonomic dysregulation of BP has been posited as a contributing factor to the elevated CVD risk in menopausal females with VMS. This review includes 1) a brief overview of the relationship between VMS and CVD, 2) mechanisms of hot flushes and their potential impact on short- and long-term BP regulation, and 3) how the disruption of autonomic function associated with VMS might provide a mechanistic pathway to CVD development. Finally, this review will highlight knowledge gaps and future directions toward better understanding of hot flush physiology and VMS contributions to CVD.

Menopausal hot flashing and endothelial function in two vascular beds: findings from a cross-sectional study of postmenopausal women

OBJECTIVE

We sought to examine the association of menopausal hot flashing with vascular reactivity in two different vascular beds in the same cohort of postmenopausal women and explore the relationship between hot flashing and cardiovascular disease (CVD) risk profile.

METHODS

A cross-sectional study of 79 healthy postmenopausal women, 23 of whom have never had menopausal hot flashes and 56 of whom have reported hot flashes. Endothelial function at a microvascular level was measured with Laser Doppler Imaging with Iontophoresis which assesses the response to both acetylcholine (Ach, endothelium dependent) and sodium-nitroprusside (SNP, endothelium independent). Reactive Hyperemia Index (RHI) was measured with peripheral arterial tonometry as a marker of endothelial function mainly at a macrovascular level. Metabolic biomarkers including insulin sensitivity were assessed.

RESULTS

Women with hot flashes had enhanced microvascular response to Ach by ∼30% (P = 0.04) and to SNP by ∼31% (P = 0.02), but lower RHI by ∼13% (P = 0.05) compared with women without flashes. Hot flashing was associated with enhanced response to SNP and lower RHI after adjustment for confounders and conventional CVD risk factors. Women with hot flashes were more insulin resistant than nonflashers (HOMAIR: 1.9 (1.2-2.6) vs 1.4 (0.8-1.9), P = 0.03).

CONCLUSIONS

Our data support the association of hot flashing with greater insulin resistance and lower macrovascular response. The paradoxical enhanced microvascular response in hot flashers could be the result of the net effect of thermoregulatory and nonnitric oxide-related pathways rather than of endothelial integrity.

What's in a name: are menopausal "hot flashes" a symptom of menopause or a manifestation of neurovascular dysregulation?

Hot flashes have typically been classified as "symptoms of menopause" that should be tolerated or treated until they resolve. However, mounting evidence points to hot flashes as a manifestation of one or several underlying pathophysiological processes. Associations exist between the presence, timing of onset, severity, and duration of hot flashes, and the risk of several neurological (affecting sleep, mood, and cognition) and cardiovascular conditions. In addition, four consistent patterns of vasomotor disturbances have been identified across different countries, making it unlikely that these patterns are solely explained by socioeconomic or cultural factors. The changing hormonal environment of menopause may unmask differences in the autonomic neurovascular control mechanisms that put an individual woman at risk for chronic conditions of aging. These differences may have a genetic basis or may be acquired across the life span and are consistent with the variability of the clinical manifestations of aging observed in women after bilateral oophorectomy. It is time to investigate the pathophysiological mechanisms underlying the four patterns of vasomotor symptoms more closely, and to shift from describing hot flashes as symptoms to be tolerated to manifestations of an underlying autonomic neurovascular dysregulation that need to be addressed.

Sex-Specific Physiology and Cardiovascular Disease

Sex differences in cardiovascular diseases can be classified as those which are specific to one sex and those that differ in incidence, prevalence, etiology, symptomatology, response to treatment, morbidity, and mortality in one sex compared to the other. All sex differences in cardiovascular conditions have their basis in the combined expression of genetic and hormonal differences between women and men. This chapter addresses how understanding basic mechanisms of hormone responses, imaging diagnostics, and integration of genomics and proteomics has advanced diagnosis and improved outcomes for cardiovascular conditions, apart from those related to pregnancy that are more prevalent in women. These conditions include obstructive coronary artery disease, coronary microvascular dysfunction, spontaneous coronary artery dissection, diseases of the cardiac muscle including heart failure and takotsubo cardiomyopathy, and conditions related to neurovascular dysregulation including hot flashes and night sweats associated with menopause and effects of exogenous hormones on vascular function. Improvement in technologies allowing for noninvasive assessment of neuronally mediated vascular reactivity will further improve our understanding of the basic etiology of the neurovascular disorders. Consideration of sex, hormonal status, and pregnancy history in diagnosis and treatment protocols will improve prevention and outcomes of cardiovascular disease in women as they age.

Cardiovascular Implications of the Menopause Transition: Endogenous Sex Hormones and Vasomotor Symptoms

The menopause transition (MT) is a critical period of women's lives marked by several physiologic changes and menopause-related symptoms that have implications for health. Risk for cardiovascular disease, the leading cause of death in women, increases after menopause, suggesting a contribution of the MT to its development. This article focuses on the relationship between 2 main features of the MT and women's cardiovascular health: (1) dynamic alterations of sex hormones, particularly endogenous estradiol and follicle-stimulating hormone, and (2) vasomotor symptoms, the cardinal symptom of the menopause. Limitations and future directions are discussed.

Proteomics in plasma of ovariectomized rats and those exposed to estradiol valerate

The menopausal period, an inevitable physiological process for women, is frequently associated with physiological and psychological dysfunction attributable to substantial fluctuation and gradual decrease in female hormones induced by ovarian failure, leading to corresponding symptoms and diseases that impact multiple systems in the body to varying degrees. As prior studies have focused primarily on menopausal syndrome-related pathophysiological changes and hormone replacement therapy effects, here we approached menopausal disease incidence risk and pathogenesis through systemic plasma proteomics analysis. Female Sprague-Dawley rats were randomly divided into sham, ovariectomized, and estrogen treatment after ovariectomy groups (n=9 per group). Tandem Mass Tag quantitative proteomics analysis of their plasma identified over 900 proteins by MS. Between group fold change of >1.2 and p<0.05 (Student's t-test) identified 121 (including 36 up-regulated and 85 down-regulated), 117 (69 up-regulated and 48 down-regulated), and 109 (41 up-regulated and 68 down-regulated) differentially expressed proteins between groups, respectively. Of these, 5 (GHR, LIFR, apoA IV, RTN, and Lin28b) were verified by parallel reaction monitoring to be reliable. Further application of optimized screening criteria and performance of a series of bioinformatics analyses allowed the selection of 35 optimal differentially expressed proteins. Gene ontology annotation results suggested that the differentially expressed proteins are mainly annotated as protein binding, cell, and single organism process in terms of molecular function, cell composition, and biological process, respectively. KEGG pathway analysis indicated that the PI3-Akt pathway has the highest aggregation degree of differentially expressed proteins. Protein-protein interaction analysis noted GLUT4 as an important node protein. This research is the first to comprehensively analyze plasma protein changes, together with estrogen efficacy, in ovariectomized rats. The findings facilitate our understanding of the molecular mechanism of systemic menopausal changes and provide valuable clues for developing diagnostic biomarkers for menopausal dysfunctions and selecting clinical therapeutic strategies.

Cardiac repolarization in recently postmenopausal women with or without hot flushes

OBJECTIVE

Menopausal hot flushes are associated with elevated activity of the sympathetic nervous system and may be related to increased risk for cardiovascular events. Sympathetic activation may trigger severe arrhythmias by modulating cardiac repolarization. The aim of this study was to evaluate the impact of hot flushes on cardiac repolarization in postmenopausal women with and without hot flushes.

METHODS

We assessed 150 recently postmenopausal healthy women-72 with hot flushes and 78 without hot flushes. They underwent 24-hour electrocardiographic recording, comprising a total of over 10,000,000 QT-interval measurements. The cardiac repolarization was assessed by measuring QT-intervals, heat rate dependence of QT-end intervals, and T-waves.

RESULTS

The maximal QT-end interval was shorter in women with hot flushes compared with those without hot flushes (481 ± 64 ms vs 493 ± 50 ms; P = 0.046). There were no differences between the rate dependence of QT-end intervals and T-wave measures between the groups. During the night-time hot flush period, we detected a steeper rate-dependence of QT-end intervals and a longer maximal T-peak-T-end interval (117 ± 54 ms vs 111 ± 56 ms; P < 0.001) compared with the control period.

CONCLUSIONS

Women with hot flushes did not have clinically significant differences in ambulatory cardiac repolarization measurements compared with asymptomatic women. However, a sudden sympathetic surge occurring during the night-time hot flush may have direct effects on cardiac repolarization.

Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

BACKGROUND

Although some unequivocal underlying mechanisms of menopausal hot flushes have been demonstrated in animal models, the paucity of similar approaches in humans impedes further mechanistic outcomes. Human studies might show some as yet unexpected physiological mechanisms of metabolic adaptation that permeate the phase of decreased oestrogen levels in both symptomatic and asymptomatic women. This is particularly relevant because both the severity and time span of hot flushes are associated with increased risk of chronic inflammatory disease. On the other hand, oestrogen induces the expression of heat shock proteins of the 70 kDa family (HSP70), which are anti-inflammatory and cytoprotective protein chaperones, whose expression is modulated by different types of physiologically stressful situations, including heat stress and exercise. Therefore, lower HSP70 expression secondary to oestrogen deficiency increases cardiovascular risk and predisposes the patient to senescence-associated secretory phenotype (SASP) that culminates in chronic inflammatory diseases, such as obesities, type 2 diabetes, neuromuscular and neurodegenerative diseases.

OBJECTIVE AND RATIONALE

This review focuses on HSP70 and its accompanying heat shock response (HSR), which is an anti-inflammatory and antisenescent pathway whose intracellular triggering is also oestrogen-dependent via nitric oxide (NO) production. The main goal of the manuscript was to show that the vasomotor symptoms that accompany hot flushes may be a disguised clue for important neuroendocrine alterations linking oestrogen deficiency to the anti-inflammatory HSR.

SEARCH METHODS

Results from our own group and recent evidence on hypothalamic control of central temperature guided a search on PubMed and Google Scholar websites.

OUTCOMES

Oestrogen elicits rapid production of the vasodilatory gas NO, a powerful activator of HSP70 expression. Whence, part of the protective effects of oestrogen over cardiovascular and neuroendocrine systems is tied to its capacity of inducing the NO-elicited HSR. The hypothalamic areas involved in thermoregulation (infundibular nucleus in humans and arcuate nucleus in other mammals) and whose neurons are known to have their function altered after long-term oestrogen ablation, particularly kisspeptin-neurokinin B-dynorphin neurons, (KNDy) are the same that drive neuroprotective expression of HSP70 and, in many cases, this response is via NO even in the absence of oestrogen. From thence, it is not illogical that hot flushes might be related to an evolutionary adaptation to re-equip the NO-HSP70 axis during the downfall of circulating oestrogen.

WIDER IMPLICATIONS

Understanding of HSR could shed light on yet uncovered mechanisms of menopause-associated diseases as well as on possible manipulation of HSR in menopausal women through physiological, pharmacological, nutraceutical and prebiotic interventions. Moreover, decreased HSR indices (that can be clinically determined with ease) in perimenopause could be of prognostic value in predicting the moment and appropriateness of starting a HRT.

Vasomotor symptoms and metabolic syndrome

A vast majority of menopausal women suffer from vasomotor symptoms, such as hot flushes and night sweats, the mean duration of which may be up to 7-10 years. In addition to a decreased quality of life, vasomotor symptoms may have an impact on overall health. Vasomotor symptoms are associated with overactivity of the sympathetic nervous system, and sympathetic overdrive in turn is associated with metabolic syndrome, which is a known risk factor for cardiovascular disease. Menopausal hot flushes have a complex relationship to different features of the metabolic syndrome and not all data point towards an association between vasomotor symptoms and metabolic syndrome. Thus, it is still unclear whether vasomotor symptoms are an independent risk factor for metabolic syndrome. Research in this area is constantly evolving and we present here the most recent data on the possible association between menopausal vasomotor symptoms and the metabolic syndrome.

Cardiovascular risk assessment in women - an update

Cardiovascular disease is the leading cause of morbidity and mortality in postmenopausal women. Although it is a disease of aging, vascular disease initiates much earlier in life. Thus, there is a need to be aware of the potential to prevent the development of the disease from an early age and continue this surveillance throughout life. The menopausal period and early menopause present an ideal opportunity to assess cardiovascular risk and plan accordingly. Generally in this period, women will be seen by primary health-care professionals and non-cardiovascular specialists. This review addresses female-specific risk factors that may contribute to the potential development of cardiovascular disease. It is important for all health-care professionals dealing with women in midlife and beyond to be cognisant of these risk factors and to initiate female-specific preventative measures or to refer to a cardiovascular specialist.

Trajectories of Vasomotor Symptoms and Carotid Intima Media Thickness in the Study of Women's Health Across the Nation

BACKGROUND AND PURPOSE

Emerging work has linked menopausal vasomotor symptoms (VMS) to subclinical cardiovascular disease (CVD) among women. However, VMS are dynamic over time. No studies have considered how temporal patterns of VMS may relate to subclinical CVD. We tested how temporal patterns of VMS assessed over 13 years were related to carotid intima media thickness (IMT) among midlife women.

METHODS

The Study of Women's Health Across the Nation is a longitudinal cohort study of midlife women. Eight hundred and eleven white, black, Hispanic, and Chinese participants with a well-characterized final menstrual period completed measures of VMS, a blood draw, and physical measures approximately annually for 13 years. Women underwent a carotid artery ultrasound at study visit 12.

RESULTS

Four trajectories of VMS were identified by trajectory analysis (consistently high, early-onset, late-onset, persistently low VMS) and tested in relation to carotid indices in linear regression models. Results indicated that women with early-onset VMS had both greater mean IMT (beta, b [standard error, SE]=0.03 [0.01], P=0.03) and greater maximal IMT (b [SE]=0.04 [0.01], P=0.008) than women with consistently low VMS, adjusting for demographics and CVD risk factors.

CONCLUSIONS

This is the first study to test trajectories of VMS in relation to subclinical CVD. Women with VMS early in the menopause transition had higher mean IMT and maximal IMT than those with consistently low VMS across the transition. Associations were not accounted for by demographic factors nor by CVD risk factors. Results can signal to women in need of early CVD risk reduction.

Vasomotor symptoms in women and cardiovascular risk markers: Systematic review and meta-analysis

We performed a systematic review and meta-analysis of the observational or interventional studies assessing the association of vasomotor symptoms (hot flushes and night sweats) with various cardiovascular risk markers (systolic (SBP) and diastolic blood pressure (DBP), hypertension, total cholesterol, body mass index (BMI), and measures of subclinical atherosclerosis), in peri-menopausal, menopausal, or postmenopausal women. Eleven unique studies were identified with data available on 19,667 non-overlapping participants. Pooled analysis showed that women with hot flushes, compared to those without, tended to have significant higher levels of SBP (mean difference (MD): 1.95 mmHg (95%CI, 0.27 to 33.63)), and DBP (MD 1.17 mmHg (95%CI, -0.21 to 2.54)) and higher odds of having hypertension (OR: 1.18, 95%CI: 0.93 to 1.51), albeit non-significant. Similarly, women who reported night sweats compared to those who did not, had significant higher levels of SBP, (MD: 1.33 mmHg (95%CI, 0.63 to 2.03)), DBP (MD: 0.55 mmHg (95%CI, 0.19 to 0.91)), total cholesterol (MD: 0.17 mmHg (95%CI, 0.03 to 0.31)) and

BMI (MD

0.64 mmHg (95%CI, 0.47 to 0.80)). Vasomotor symptoms in women were not associated with measures of subclinical atherosclerosis. Women with vasomotor symptoms may have an unfavorable cardiovascular risk profile compared to women without vasomotor complaints.

Vascular function and cardiovascular risk factors in women with severe flushing

Cardiovascular disease is the leading cause of death in women of postmenopausal age worldwide. It is a relatively rare occurrence before the menopause and the increase in incidence coincides with the most common symptom associated with menopausal transition, hot flushing. Interest in cardiovascular disease post-menopause has largely focused on the effect of hormone therapy on risk of coronary events and stroke, with vasomotor symptoms considered merely a nuisance symptom, but recent work suggests that the presence of flushing may be a marker of underlying cardiovascular disease.

Postmenopausal hot flushes and bone mineral density: a longitudinal study

OBJECTIVE

To study the possible association between menopausal hot flushes and bone mineral density.

DESIGN

Observational study.

SETTING

University clinic.

POPULATION

Healthy women (n = 143) with or without hot flushes, 6-36 months postmenopausal after participating in a 6-month hormone therapy trial.

METHODS

The women prospectively recorded the number and severity of hot flushes for 2 weeks. Bone mineral density in lumbar and hip bones was measured with dual-energy X-ray absorptiometry at recruitment and reassessed in 114 women approximately 6.2 years later.

MAIN OUTCOME MEASURES

Hot flushes and bone mineral density.

RESULTS

At recruitment, hot flushes were absent in 22 women, mild in 32, moderate in 28, and severe in 61. Lumbar bone mineral densities in non-flushing women (1.130 ± 0.022 g/cm(2) ; mean ± SEM), and in those with mild (1.088 ± 0.024 g/cm(2) ), moderate (1.082 ± 0.030 g/cm(2) ) or severe (1.102 ± 0.019 g/cm(2) ) hot flushes did not differ, nor were there differences in hip bone mineral densities between the four study groups. During the follow-up, lumbar bone mineral density decreased by a mean of 0.4 ± 0.1% a year in women not using hormone therapy, and increased by 0.1 ± 0.2% a year in hormone therapy users (p = 0.019). The respective non-significant changes in left and right total hip bone mineral densities were - -0.6 ± 0.01 and -1.0 ± 0.1 for the non-users, and -0.4 ± 0.1 and -0.6 ± 0.2 for hormone therapy users. These changes in bone mineral density bore no relation to the hot flush status at baseline.

CONCLUSION

In recently menopausal women, hot flushes do not appear to determine bone mass density.

Hot flushes and night sweats are associated with coronary heart disease risk in midlife: a longitudinal study

OBJECTIVE

The purpose of this study was to investigate associations between vasomotor menopausal symptoms (VMS), i.e. hot flushes and night sweats, and the incidence of coronary heart disease (CHD).

DESIGN

A prospective cohort study.

SETTING AND POPULATION

11 725 women, aged 45-50 years at baseline in 1996, were followed up at 3-year intervals for 14 years.

METHODS

Self-reported VMS and incident CHD were measured at each survey.

MAIN OUTCOME MEASURE

We determined the association between VMS and CHD at the subsequent survey, using generalised estimating equation analysis, adjusting for time-varying covariates.

RESULTS

At baseline, 14% reported rarely, 17% reported sometimes, and 7% reported often having night sweats. During follow-up, 187 CHD events occurred. In the age-adjusted analysis, women who reported their frequency of experiencing hot flushes and night sweats as 'often' had a greater than two-fold increased odds of CHD (OR hot flushes 2.18, 95% CI 1.49-3.18; OR night sweats 2.38, 95% CI 1.62-3.50) compared with women with no symptoms (P trend < 0.001 for frequency of symptoms). Adjustment for menopausal status, lifestyle factors, body mass index, diabetes, and hypertension attenuated the associations (OR hot flushes 1.70, 95% CI 1.16-2.51, P trend = 0.01; OR night sweats 1.84, 95% CI 1.24-2.73), P trend = 0.004).

CONCLUSIONS

Women who report having hot flushes or night sweats 'often' have an increased risk of developing CHD over a period of 14 years, even after taking the effects of age, menopause status, lifestyle, and other chronic disease risk factors into account.

Vasomotor symptoms and insulin resistance in the study of women's health across the nation

CONTEXT

Emerging research suggests links between menopausal hot flashes and cardiovascular disease risk. The mechanisms underlying these associations are unclear, due to the incomplete understanding of the physiology of hot flashes. OBJECTIVE AND MAIN OUTCOME MEASURES: We examined the associations between hot flashes/night sweats and glucose and insulin resistance over 8 yr, controlling for cardiovascular risk factors and reproductive hormones.

DESIGN, SETTING, AND PARTICIPANTS

Participants in the Study of Women's Health Across the Nation (SWAN) (n=3075), a longitudinal cohort study, were ages 42-52 yr at entry. Women completed questionnaires (hot flashes, night sweats: none, 1-5 d, ≥6 d, past 2 wk), physical measures (blood pressure, height, weight), and a fasting blood draw [serum glucose, insulin, estradiol (E2), FSH] annually for 8 yr. Hot flashes/night sweats were examined in relation to glucose and the homeostasis model assessment (HOMA) in mixed models, adjusting for demographics, cardiovascular risk factors, medications, and E2/FSH.

RESULTS

Compared to no flashes, hot flashes were associated with a higher HOMAlog index [vs. none; hot flashes, 1-5 d: % difference (95% confidence interval), 2.37 (0.36-4.43), P=0.02; and ≥6 d: 5.91 (3.17-8.72), P<0.0001] in multivariable models that included body mass index. Findings persisted adjusting for E2 or FSH, and were similar for night sweats. Findings were statistically significant, yet modest in magnitude, for the outcome glucose.

CONCLUSIONS

Hot flashes were associated with a higher HOMA index, an estimate of insulin resistance, and to a lesser extent higher glucose. Metabolic factors may be relevant to understanding the link between hot flashes and cardiovascular disease risk.

Are vasomotor symptoms associated with alterations in hemostatic and inflammatory markers? Findings from the Study of Women's Health Across the Nation

OBJECTIVE

Emerging research suggests links between menopausal hot flashes and cardiovascular risk. The mechanisms underlying these associations are unclear due, in part, to the incomplete understanding of the physiology of hot flashes. We aimed to examine the longitudinal associations between hot flashes/night sweats and both inflammatory and hemostatic markers, controlling for cardiovascular risk factors and estradiol concentrations.

METHODS

Participants in the Study of Women's Health Across the Nation (n = 3,199), a longitudinal cohort study, were aged 42 to 52 years at cohort entry. Women completed interviews (hot flashes, night sweats: none, 1-5, and ≥6 d in the past 2 weeks), physical measures (blood pressure, height, weight), and a blood draw (high-sensitivity C-reactive protein, plasminogen activator inhibitor-1, factor VIIc, tissue plasminogen activator antigen [tPA-ag], fibrinogen, glucose, serum estradiol) yearly for 8 years. Hot flashes/night sweats were examined in relation to each inflammatory/hemostatic marker in linear mixed models adjusting for demographic factors, cardiovascular risk factors, and medication use, as well as serum estradiol.

RESULTS

Compared with experiencing no flashes, reporting hot flashes was associated with higher tPA-aglog (hot flashes 1-5 d: percent change, or % change [95% CI], 3.88 [2.22-5.58]; P < 0.0001; ≥6 d: % change [95% CI], 4.11 [1.95-6.32]; P < 0.001) and higher factor VIIclog (hot flashes ≥6 d: % change [95% CI], 2.13 [0.80-3.47]; P < 0.01) in multivariable models. Findings persisted after adjusting for estradiol. Findings for night sweats were similar but attenuated with adjustment.

CONCLUSIONS

Frequent hot flashes were associated with higher factor VIIc and tPA-ag. Hemostatic pathways may be relevant to understanding hot flash physiology and links between hot flashes and cardiovascular risk.

Primary Prevention of Cardiovascular Disease with HRT

Prevention of cardiovascular disease has increasingly important health implications as our population ages. Menopause is associated with the development of cardiovascular risk factors and there are many plausible biological mechanisms through which estrogen may confer cardiovascular protection. Despite a wealth of observational data to support the use of estrogen, large randomized controlled trials failed to demonstrate a benefit. It is now becoming clearer that the beneficial cardiovascular effects of estrogen are greatest in younger women and those closest to menopause. This has led to the development of the timing hypothesis. Use of age-appropriate estrogen doses is crucial to maximize cardiovascular benefits while minimizing risk of adverse effects such as venous thromboembolism and stroke.

Hot flashes and carotid intima media thickness among midlife women

OBJECTIVE

Emerging evidence suggests associations between menopausal hot flashes and cardiovascular risk. However, whether hot flashes are associated with intima media thickness (IMT) or IMT changes over time is unknown. We hypothesized that reported hot flashes would be associated with greater IMT cross-sectionally and with greater IMT progression over 2 years.

METHODS

Participants were 432 women aged 45 to 58 years at baseline participating in the Study of Women's Health Across the Nation (SWAN) Heart, an ancillary study to the SWAN. Measures at the SWAN Heart baseline and follow-up visit 2 years later included a carotid artery ultrasound, reported hot flashes (past 2 weeks: none, 1-5 d, ≥6 d), and a blood sample for measurement of estradiol.

RESULTS

Women reporting hot flashes for 6 days or more in the prior 2 weeks had significantly higher IMT than did women without hot flashes at the baseline (mean [SE] difference, 0.02 [0.01] mm; P=0.03) and follow-up (mean [SE] difference, 0.02 [0.01] mm; P=0.04) visits, controlling for demographic factors and cardiovascular risk factors. Reporting hot flashes at both study visits was associated with higher follow-up IMT relative to reporting hot flashes at neither visit (mean [SE] difference, 0.03 [0.01] mm; P=0.03). Associations between hot flashes and IMT largely remained after adjusting for estradiol. An interaction between hot flashes and obesity status was observed (P=0.05) such that relations between hot flashes and IMT were observed principally among overweight/obese women. Hot flashes were not associated with IMT progression.

CONCLUSIONS

These findings provide some indication that women reporting hot flashes for 6 days or more in the prior 2 weeks may have higher IMT than do women without hot flashes, particularly for women who are overweight or obese. Further work should determine whether hot flashes mark adverse underlying vascular changes.

Sex, hormones and neuroeffector mechanisms

Incidence and rate of cardiovascular disease differ between men and women across the life span. Although hypertension is more prominent in men than women, there is a group of vasomotor disorders [i.e. Raynaud's disease, postural orthostatic tachycardia syndrome and vasomotor symptoms (hot flashes) of menopause and migraine] with a female predominance. Both sex and hormones interact to modulate neuroeffector mechanisms including integrated regulation of the Sry gene and direct effect of sex steroid hormones on synthesis, release and disposition of monoamine neurotransmitters, and distribution and sensitivity of their receptors in brain areas associated with autonomic control. The interaction of the sex chromosomes and steroids also modulates these effector tissues, that is, the heart, vascular smooth muscle and endothelium. Although involvement of central serotonergic centres has been studied in regard to mood disorders such as depression, their contribution to cardiovascular risk is gaining attention. Studies are needed to further evaluate how hormonal treatments and drugs used to modulate adrenergic and serotonergic activity affect progression and risk for cardiovascular disease in men and women.

Increased cortisol level: a possible link between climacteric symptoms and cardiovascular risk factors

OBJECTIVE

Vasomotor symptoms may increase the risk for cardiovascular diseases through still elusive mechanisms. Increased cortisol release may favor atherosclerosis. In this study, we tested whether vasomotor and psychological symptoms are associated with an increase in cortisol levels.

METHODS

A cross-sectional investigation on women in early menopause enrolled consecutively between January and June 2009 was conducted. This study was set at a menopause outpatient service at University Hospital. Participants included 85 healthy women who were 6 months to 5 years postmenopause. The 24-hour urinary cortisol level and Greene Climacteric Scale scores were evaluated. Anthropometric parameters and fasting blood samples for the determination of high-density lipoprotein (HDL) cholesterol, total cholesterol, triglycerides, glucose, and insulin levels were measured. Body mass index, waist-to-hip ratio, and homeostatic model assessment of insulin resistance were calculated. The relation between Greene Climacteric Scale scores and 24-hour urinary cortisol level and between 24-hour urinary cortisol level and lipid levels or insulin resistance was determined.

RESULTS

The Greene Climacteric Scale score for climacteric symptoms (coefficient of regression [CR], 1.343; 95% CI, 0.441-2.246) and body mass index (CR, 4.469; 95% CI, 1.259-7.678) explained 32.5% and 10.3%, respectively, of the variance in 24-hour urinary cortisol level (r = 0.428; P = 0.0003). Twenty-four-hour urinary cortisol level was inversely related to HDL-cholesterol level (CR, -0.065; 95% CI, -0.114 to -0.017; r = 0.283; P = 0.009) and was related to waist girth (CR, 0.685; 95% CI, 0.306-1.063) and homeostatic model assessment of insulin resistance (CR, 0.097; 95% CI, 0.032-0.162; r = 0.510; P = 0.0001).

CONCLUSIONS

In early postmenopausal women, the Greene Climacteric Scale score is associated with increased 24-hour urinary cortisol level. Increased cortisol level is associated with known risk factors for cardiovascular disease, such as insulin resistance and decreased HDL-cholesterol level.

Vasomotor symptoms and cardiovascular events in postmenopausal women

OBJECTIVE

Emerging evidence suggests that women with menopausal vasomotor symptoms (VMS) have increased cardiovascular disease (CVD) risk as measured by surrogate markers. We investigated the relationships between VMS and clinical CVD events and all-cause mortality in the Women's Health Initiative Observational Study (WHI-OS).

METHODS

We compared the risk of incident CVD events and all-cause mortality between four groups of women (total N = 60,027): (1) no VMS at menopause onset and no VMS at WHI-OS enrollment (no VMS [referent group]), (2) VMS at menopause onset but not at WHI-OS enrollment (early VMS), (3) VMS at both menopause onset and WHI-OS enrollment (persistent VMS [early and late]), and (4) VMS at WHI-OS enrollment but not at menopause onset (late VMS).

RESULTS

For women with early VMS (n = 24,753), compared with no VMS (n = 18,799), hazard ratios (95% CIs) in fully adjusted models were as follows: major coronary heart disease (CHD), 0.94 (0.84-1.06); stroke, 0.83 (0.72-0.96); total CVD, 0.89 (0.81-0.97); and all-cause mortality, 0.92 (0.85-0.99). For women with persistent VMS (n = 15,084), there was no significant association with clinical events. For women with late VMS (n = 1,391), compared with no VMS, hazard ratios (95% CIs) were as follows: major CHD, 1.32 (1.01-1.71); stroke, 1.14 (0.82-1.59); total CVD, 1.23 (1.00-1.52); and all-cause mortality, 1.29 (1.08-1.54).

CONCLUSIONS

Early VMS were not associated with increased CVD risk. Rather, early VMS were associated with decreased risk of stroke, total CVD events, and all-cause mortality. Late VMS were associated with increased CHD risk and all-cause mortality. The predictive value of VMS for clinical CVD events may vary with the onset of VMS at different stages of menopause. Further research examining the mechanisms underlying these associations is needed. Future studies will also be necessary to investigate whether VMS that develop for the first time in the later postmenopausal years represent a pathophysiologic process distinct from the classic perimenopausal VMS.

Menopausal hot flushes and vascular health

Hot flushes are complained of by approximately 75% of all postmenopausal women, and hormone therapy (HT) is the most effective way to alleviate them. Hot flushes are characterized by altered vascular function and sympathetic nervous system activity. Hot flushes occurred more often in women attending large, non-randomized observational studies (e.g. Nurses' Health Study), where HT use protected against cardiovascular disease (CVD). However, they were absent (or mild) in randomized HT trials where HT use was accompanied with an elevated risk for CVD. Hot flushes, if a factor for cardiovascular health, could partly explain the conflict between observational and randomized trials. Several cross-sectional studies imply that hot flushes are detrimental to the cardiovascular system. However, the data are not uniform, and hot flushes were recalled retrospectively or during HT use. In our prospective study hot flushes were accompanied with a vasodilatory effect during endothelial testing, and this was related to the severity of hot flushes. Night-time hot flushes were followed with transient rises in ambulatory blood pressure (BP). However, no effect of hot flushes on diurnal BP was detected. The use of estradiol showed no harmful effects on endothelial function in women with hot flushes, but in non-flushing women oral, but not transdermal, estradiol led to vasoconstrictive changes. Estradiol complemented with medroxyprogesterone acetate eliminated the vasoconstrictive effect of sole oral estradiol. Thus, both oral and transdermal estradiol are applicable in flushing women, whereas a transdermal route should be favored in non-flushing women if used e.g. for bone protection.

Vasomotor hot flushes and 24-hour ambulatory blood pressure in recently post-menopausal women

BACKGROUND

Menopausal hot flushes may be a marker for a difference in vascular function. We studied the associations between hot flushes of varying severity and ambulatory blood pressure (BP) and heart rate (HR).

METHODS

A total of 147 women with onset of menopause within the preceding 6-36 months reported no hot flushes (n = 23) or mild (n = 33), moderate (n = 30), or severe (n = 61). Ambulatory BP and HR were registered for 24 hours. The variables, analyzed separately for day-time and night-time, were compared among the four study groups.

RESULTS

Hot flushes failed to show any relationship to mean day- or night-time BP, nocturnal dipping of BP, or HR. However, severe night-time hot flushes were accompanied by elevations in systolic BP (4.1 +/- 10.5 mmHg, P = 0.061), diastolic BP (3.1 +/- 6.8 mmHg, P = 0.032), and heart rate (3.0 +/- 7.2 beats/minute, P = 0.043).

CONCLUSION

Hot flushes are not associated with ambulatory BP or heart rate in normotensive, recently post-menopausal women, although severe night-time hot flush episodes are followed by significant elevations in BP and heart rate. The latter may be of clinical significance.

Effect of hot flushes on vascular function: a randomized controlled trial

OBJECTIVE

To compare the vascular responses to hormone therapy in women with and without hot flushes.

METHODS

We randomly assigned 143 healthy, recently postmenopausal women (mean age 52.4+/-0.2 years, time since menopause 19.5+/-0.9 months) with intolerable hot flushes (more than seven moderate/severe episodes per day) or tolerable hot flushes (fewer than three mild episodes per day) to receive 1 mg of transdermal estradiol gel, oral estradiol (2 mg) with and without daily medroxyprogesterone acetate, or placebo for 6 months. Vascular function was assessed by pulse-wave analysis and endothelial function testing with nitroglycerin and salbutamol challenges.

RESULTS

Hot flushes did not affect the changes in arterial or aortic stiffness or endothelial function in response to various forms of hormone therapy. However, in women with tolerable hot flushes, oral estradiol caused a decrease of 13.2% (P=.028) in the time to the first systolic peak (dependent on the rapid phase of ventricular ejection) after nitroglycerin. In addition, the time to the reflected wave (dependent on pulse-wave velocity) after nitroglycerin was decreased by 8.4% (P=.018). These effects were not seen in women with intolerable hot flushes or with the other treatment regimens.

CONCLUSION

Women without troublesome hot flushes are susceptible to unfavorable vascular effects after oral estrogen treatment, resulting in less compliant vasculature.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00668603.

LEVEL OF EVIDENCE

I.

Hot flashes and blood pressure in midlife women

OBJECTIVES

Recent epidemiological studies suggest that hot flashes may have a detrimental impact on the cardiovascular system. The purpose of this study was to examine the associations between hot flashes and blood pressure among women aged 45-54 years who had never used hormone therapy.

STUDY DESIGN

Data were analyzed from 603 women who participated in the Midlife Health Study, a cross-sectional study conducted in the Baltimore Metropolitan region.

MAIN OUTCOME MEASURES

All participants came to the clinic where systolic and diastolic blood pressures were measured, height and weight were assessed, and a questionnaire was administered that ascertained detailed data on history of hot flashes and participant demographics and health habits.

RESULTS

The data showed that 56.9% of the participants reported ever experiencing hot flashes. In the age-adjusted analyses, both systolic and diastolic blood pressures were significantly and positively associated with hot flashes. However, the estimates were markedly attenuated and not statistically significant after adjustment for age, race, smoking status, current alcohol use, body mass index, and use of an anti-hypertensive agent or a cholesterol-lowering medication. Similar results were observed for moderate or severe hot flashes, hot flashes experienced for one or more years, and hot flashes experienced within the previous 30 days.

CONCLUSIONS

These findings indicate that hot flashes are not significantly associated with blood pressure during midlife.