The association of calcium supplementation and incident cardiovascular events in the Multi-ethnic Study of Atherosclerosis (MESA).

BACKGROUND AND AIMS: Many US adults use calcium supplements to address inadequate dietary intake and improve bone health. However, recent reports have suggested that use of calcium supplements may elevate cardiovascular disease (CVD) risk. In this study, we examined associations between baseline calcium supplement use and incident myocardial infarction (MI) (n = 208 events) and CVD events (n = 641 events) over 10.3 years in men and women from the Multi-Ethnic Study of Atherosclerosis (MESA) cohort (n = 6236), with dietary calcium intake at baseline also examined as a supplementary objective. METHODS AND RESULTS: Using Cox proportional hazards models, no compelling associations between calcium intake from supplements or diet and incident CVD events were observed upon multivariate adjustment for potential confounders. An association with lower MI risk was observed comparing those with low levels of calcium supplement use (1-499 mg) to those using no calcium supplements (hazard ratio 0.69, 95% CI 0.48, 0.98, p = 0.039). Relationships were homogeneous by gender, race/ethnicity, or chronic kidney disease. Results were also similar when the analysis was limited to postmenopausal women only. CONCLUSION: Analysis of incident MI and CVD events in the MESA cohort does not support a substantial association of calcium supplement use with negative cardiovascular outcomes.

The relationship between inflammation, obesity and risk for hypertension in the Multi-Ethnic Study of Atherosclerosis (MESA).

It has been suggested that inflammation is important in the aetiology of hypertension and that this may be most relevant among obese persons. To study this, we examined the independent relationships between obesity, inflammation-related proteins (interleukin-6 (IL-6), C-reactive protein (CRP) and fibrinogen) and risk for hypertension in the Multi-Ethnic Study of Atherosclerosis (MESA). Hypertension status, defined as a blood pressure ≥140/90 mm Hg or a history of hypertension and use of blood pressure medications, was determined at baseline and two subsequent exams over 5 years. Among 3543 non-hypertensives at baseline, 714 individuals developed incident hypertension by Exam 3. Cox proportional hazard models were used to determine the relationship between baseline levels of IL-6, CRP and fibrinogen and future risk of hypertension. One s.d. difference in baseline concentration of IL-6, CRP or fibrinogen was associated with 20-40% greater risk of incident hypertension. This risk was attenuated after accounting for other hypertension risk factors (hazard ratio (HR) IL-6: 1.13 (95% CI: 1.04-1.23); CRP: 1.11 (95% CI: 1.02-1.21); fibrinogen 1.0 (95% CI: 0.92-1.08)). Conversely, obesity was an independent risk factor for hypertension risk, minimally impacted by other covariates, including IL-6 and CRP (HR 1.72 (95% CI: 1.36-2.16)). IL-6 and CRP did not modify the relationship between obesity and hypertension, though an adjusted twofold greater risk was observed for obese individuals with a CRP >3 mg l⁻¹ compared with CRP <1 mg l⁻¹. The relationship between inflammation-related proteins and hypertension risk was predominantly explained by other hypertension risk factors. Obesity, independent of inflammation, remained a potent risk factor for future hypertension.

Endothelial dysfunction is associated with left ventricular mass (assessed using MRI) in an adult population (MESA).

Brachial flow-mediated dilation (FMD) is a measure of endothelial nitric oxide bioavailability. Endothelial nitric oxide controls vascular tone and is likely to modify the ventricular muscle coupling mechanism. The association between left ventricular mass and FMD is not well understood. We assessed the association between left ventricular mass index (LVMI) and FMD in participants of the Multi-Ethnic Study of Atherosclerosis (MESA). MESA is a population-based study of 6814 adults free of clinical cardiovascular disease at baseline who were recruited from six US clinics. LVMI (left ventricular mass per body surface area) and FMD were measured in 2447 subjects. Linear regression analysis was used to evaluate the association. The subjects had a mean age of 61.2±9.9 years, 51.2% females with 34.3% Caucasians, 21.6% Chinese, 19.4% African Americans and 24.7% Hispanics. The mean body mass index (BMI) was 27.4±4.8 kg m⁻², 9.4% had diabetes, 11% were current smokers and 38% hypertensives. The mean±s.d. LVMI was 78.1±15.9 g m⁻² and mean±s.d. FMD was 4.4%±2.8%. In univariate analysis, LVMI was inversely correlated with FMD (r= -0.20, P<0.0001). In the multivariable analysis, LVMI was associated with FMD (ß coefficient (se) = -0.50 (0.11), P<0.001 (0.5 g m⁻² reduction in LVMI per 1% increase in FMD)) after adjusting for age, gender, race/ethnicity, systolic blood pressure, diabetes mellitus, smoking, weight, statin use, antihypertensive medication use, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol. The association between brachial flow mediated dilation and LVMI maybe independent of traditional CV risk factors in population based adults.

The minor allele of GP6 T13254C is associated with decreased platelet activation and a reduced risk of recurrent cardiovascular events and mortality: results from the SMILE-Platelets project.

BACKGROUND: Contradictory results have been published on the effects of T13254C (rs1613662), which distinguishes the two major isoforms of GP6, the gene encoding the platelet receptor glycoprotein VI, on platelet function and the risk of cardiovascular disease. METHODS: We performed a population-based case-control study, the Study of Myocardial Infarctions in Leiden, among 547 male patients with a first myocardial infarction (MI) and 646 control subjects, as well as a prospective cohort study in which the same MI patients were followed for recurrent events (fatal and non-fatal MI and unstable angina) and mortality (median follow-up of 12 years). P-selectin expression by platelets induced by crosslinked collagen-related peptide (CRP-XL) was measured by whole blood flow cytometry in 274 MI patients. RESULTS: T13254C was not associated with a first MI, but seemed to be associated with a reduced incidence of recurrent events [per-allele hazard ratio 0.77, 95% confidence interval (CI) 0.56-1.06] and mortality (hazard ratio 0.57, 95% CI 0.37-0.89). Pooling with the Heart and Estrogen/Progestin Replacement Study revealed hazard ratios of 0.81 (95% CI 0.66-0.99) and 0.73 (95% CI 0.55-0.96). The minor C-allele was also strongly associated with a reduced percentage of P-selectin-expressing platelets. The reduction per C-allele was 23% (95% CI 18-28%). In an independent study of 219 healthy volunteers, the per-allele reduction of CRP-XL-induced aggregation was 10% (95% CI 2-18%). CONCLUSION: The minor allele of GP6 T13254C that reduced platelet activation and aggregation also seemed to be associated with a reduced incidence of recurrent cardiovascular events and mortality, but was not associated with first MI.

Genetic epidemiology of subclinical cardiovascular disease in the diabetes heart study.

A genome-wide linkage scan of 357 European American (EA) and 72 African American (AA) pedigrees multiplex for type 2 diabetes mellitus (T2DM) was performed with multipoint nonparametric QTL linkage analysis. Four subclinical measures of cardiovascular disease (CVD): coronary artery (CCP), carotid artery (CarCP), and abdominal aortic calcified plaque (AACP) and carotid artery intima-media thickness (IMT) were mapped. Analyses were adjusted for age, gender, body mass index, and (if appropriate) ethnicity and diabetes status. Evidence for linkage was observed in EA T2DM subjects to CarCP near 16p13 (LOD=4.39 at 8.4 cM; P = 0.00001). When all EA subjects were included, the LOD score was 2.52, suggesting an amplification of the linkage by diabetes. Linkage analysis of a principal components measure of vascular calcium (LOD = 3.85 at 9.3 cM on 16p in EA T2DM subjects) and bivariate analysis of CarCP X IMT (LOD = 3.77 at 9.3 cM on 16p in EA T2DM subjects) were consistent with this linkage. In addition, evidence for linkage was observed with CCP near D15S1515 (LOD = 2.34) in EAs. Additional loci on chromosomes 1, 2, 7, 10, 13, and 21 had LODs > 2.0. The identification of trait-determining polymorphisms underlying these linkages will help delineate risk factors for CVD in T2DM and the general population.

Beneficial effects of aggressive low-density lipoprotein cholesterol lowering in women with stable coronary heart disease in the Treating to New Targets (TNT) study.

OBJECTIVE: To examine by secondary analysis of the Treating to New Targets (TNT) study whether the benefits of intensive versus standard levels of lipid lowering are equally applicable to women. METHODS: A total of 10 001 patients (1902 women) with stable coronary heart disease (CHD) were randomised to double-blind treatment with atorvastatin 10 or 80 mg/day for a median follow-up of 4.9 years. RESULTS: In women and men, intensive treatment with atorvastatin 80 mg significantly reduced the rate of major cardiovascular events compared with atorvastatin 10 mg. Among women, the relative and absolute reductions were 27% and 2.7%, respectively (hazard ratio (HR) = 0.73, 95% confidence interval (CI) 0.54 to 1.00, p = 0.049). In men, the corresponding rate reductions were 21% and 2.2% (HR = 0.79, 95% CI 0.69 to 0.91, p = 0.001). The number needed to treat value (to prevent one cardiovascular event over 4.9 years compared with patients treated with atorvastatin 10 mg) for atorvastatin 80 mg was 29 for women and 30 for men. Rates of death of non-cardiovascular origin in the atorvastatin 80 mg and atorvastatin 10 mg were 3.6% and 1.6%, respectively (p = 0.004) among women, and 2.8% and 3.1% (p = 0.47) among men. CONCLUSION: Intensive lipid-lowering treatment with atorvastatin 80 mg produced significant reductions in relative risk for major cardiovascular events compared with atorvastatin 10 mg in both women and men with stable CHD.

Post-challenge glucose predicts coronary atherosclerotic progression in non-diabetic, post-menopausal women.

AIMS: We sought to determine whether fasting or post-challenge glucose were associated with progression of coronary atherosclerosis in non-diabetic women. METHODS: We performed a post-hoc analysis of 132 non-diabetic women who underwent 75-g oral glucose tolerance testing. The primary outcome of interest was progression of atherosclerosis determined by baseline and follow-up coronary angiography, a mean of 3.1 +/- 0.9 years apart. We analysed the association of change in minimal vessel diameter (DeltaMD) by quartile of fasting and post-challenge glucose using mixed models that included adjustment for age, systolic blood pressure, total : high-density lipoprotein cholesterol ratio, current smoking, lipid-lowering and anti-hypertensive medication use and other covariates. RESULTS: At baseline, participants had a mean age of 65.7 +/- 6.7 years and a mean body mass index of 27.9 +/- 8.5 kg/m(2). Although there were no significant differences in atherosclerotic progression by fasting glucose category (P for trend across quartiles = 0.99), there was a significant inverse association between post-challenge glucose and DeltaMD (in mm) (Q1 : 0.01 +/- 0.03; Q2 : 0.08 +/- 0.03; Q3 : 0.13 +/- 0.03; Q4 : 0.11 +/- 0.03; P for trend = 0.02). CONCLUSIONS: In post-menopausal women without diabetes, post-challenge glucose predicts angiographic disease progression. These findings suggest that even modest post-challenge hyperglycaemia influences the pathogenesis of atherosclerotic progression.

Effects of hormone therapy on blood pressure and the renin-angiotensin system in postmenopausal women.

Observational studies have documented an association between lower rates of cardiovascular disease and hormone therapy (HT). Meanwhile, randomized clinical trials have documented increased rates of myocardial infarction and stroke in women receiving hormone therapy. These seemingly discordant findings have stimulated new research to examine estrogen's effects on the cardiovascular system, including its effects on blood pressure, regulation of the renin-angiotensin system (RAS), and the clinical consequences of hypertension. In the last 6 years several studies have better defined the mechanisms by which HT affect the RAS, blood pressure, and the clinical effects of hypertension. Recent studies documented increases in angiotensinogen synthesis and the suppression of active renin with estrogen replacement. Genotype may be a factor in determining the degree of suppression of angiotensin converting enzyme levels that occurs with estrogen therapy. Estrogen supplementation in postmenopausal women increases systemic angiotensin II, a potent vasoconstrictor. This vasopressor effect is attenuated by an estrogen-induced reduction of angiotensin II type 1 receptor expression. Renal blood flow reduction, in the absence of blood pressure changes, have been reported after estrogen replacement, and an increased risk of total stroke has been demonstrated in hypertensive women on HT compared to normotensive women on this therapy. Estrogen replacement affects many components of the RAS, but its effect on this system has little effect on blood pressure. Further studies are needed to describe the effects of estrogen replacement on abnormal vasculature and how these effects relate to myocardial infarction and stroke.

Hormone replacement therapy is associated with increased C-reactive protein in women with Type 2 diabetes in the Diabetes Heart Study.

AIMS: Increased levels of inflammatory biomarkers, especially C-reactive protein (CRP), are associated with increased risk for cardiovascular disease (CVD) events, such as myocardial infarction, stroke, peripheral vascular disease, and sudden cardiac death. Medical interventions that increase CRP levels, such as hormone replacement therapy (HRT) in post-menopausal women, are under increasing scrutiny. The effect of HRT on CRP levels in women with Type 2 diabetes (T2DM) is not well documented, and conflicting conclusions have been reported. The aim of this study was to determine the influence of HRT on women with diabetes in a large cross-sectional study. METHODS: Three hundred and twenty-seven post-menopausal women with T2DM from the Diabetes Heart Study participated. Current use of HRT was determined and serum CRP levels were measured using a high-sensitivity ELISA kit. Generalized estimating equation methods were used to assess the relationship of multiple clinical and lifestyle (e.g. smoking) measures on CRP levels including differences between women taking HRT (HRT+) and not taking HRT (HRT-). RESULTS: Overall serum CRP levels were strongly associated with body mass index (P < 0.0001) and age (P < 0.0001). Of the women, 243 were not using HRT and 84 were using HRT. HRT+ and HRT- women did not differ significantly in measures of clinical traits, with the exception of higher mean low-density lipoprotein cholesterol in HRT- women (P = 0.004). In all models tested, HRT+ women had significantly higher circulating CRP levels, with P-values ranging from 0.0045 to 0.010. CONCLUSIONS: In this study of serum CRP concentration as a function of HRT in women with Type 2 diabetes, there was consistent evidence for increased circulating CRP levels in women receiving oestrogen-containing HRT. Whether HRT-induced increases in CRP can account for the adverse cardiovascular effects of HRT remains to be established; however, based on these data, there is little reason to believe that diabetic women would be spared from such an effect.

The impact of ethnicity and sex on subclinical cardiovascular disease: the Diabetes Heart Study.

AIMS/HYPOTHESIS: African-Americans with type 2 diabetes and access to adequate healthcare are at lower risk of clinical coronary artery disease than are white diabetic patients. We evaluated whether ethnic differences in subclinical cardiovascular disease, coronary and carotid artery calcified plaque and carotid artery intima-medial thickness (IMT) were present in members of The Diabetes Heart Study families. SUBJECTS AND METHODS: In a bi-racial cohort of 1,180 individuals from families enriched for members with type 2 diabetes, we calculated coronary and carotid artery calcified plaque using fast-gated helical computed tomography, and measured carotid artery IMT and clinical risk factor profiles. Generalised estimating equations were used to test for an association between measures of subclinical cardiovascular disease and ethnicity and sex. RESULTS: After adjustment for age, ethnicity and kidney function, African-Americans had significantly lower amounts of coronary artery calcified plaque (mean+/-SE) (866+/-158 vs 1,915+/-135, respectively; p=0.0466) and carotid artery calcified plaque (179+/-51 vs 355+/-27, respectively; p=0.0240) relative to whites, despite having increased carotid IMT (0.71+/-0.01 vs 0.67+/-0.004 cm, respectively; p=0.0007), and higher blood pressure, albuminuria and HbA1c. Sex-specific analyses revealed that African-American men had significantly lower coronary and carotid artery calcified atheroma than white men. In women, ethnic differences in calcified carotid artery plaque, but not coronary artery plaque, were observed. CONCLUSIONS/INTERPRETATION: In families enriched for members with type 2 diabetes, African-American men had markedly lower levels of coronary and carotid artery calcified plaque than white men, despite increased carotid artery IMT and conventional risk factors. These findings suggest that susceptibility to subclinical cardiovascular disease differs markedly according to ethnicity and sex.

Effects of hormone therapy on C-reactive protein and IL-6 in postmenopausal women: a review article.

The results of the Women's Health Initiative, showing an increase in coronary heart disease events in postmenopausal women on estrogen and medroxyprogesterone acetate, have created considerable interest in finding an underlying mechanism that may confer cardiovascular risk in women on hormone therapy (HT). Inflammation is thought to play a key role in the progression of atherosclerosis. C-reactive protein (CRP) is an inflammatory marker that has been studied as a predictor of future coronary risk. Interleukin 6 (IL-6) is felt to be an important cytokine in the inflammatory cascade and instrumental in CRP expression. The purpose of this article is to summarize the observational and randomized studies that examine the difference in IL-6 and CRP concentrations with respect to oral versus transdermal hormone therapy. We also review studies looking at differences in CRP levels based on the progestin component of HT and trials examining the effect of estrogen agonists on IL-6 and CRP. In our review, we found CRP levels to be elevated in the majority of postmenopausal women on oral HT. There was no correlation between IL-6 and CRP levels. Studies examining the effect of progestins produced varying results. Transdermal estrogen, in contrast, showed no elevation in levels of IL-6 or CRP alone or with the addition of progestins. Selective estrogen receptor agonists (SERMs) did not demonstrate an effect on CRP levels, although tibolone did increase CRP in one reviewed trial. Questions remain about the role of progestins and transdermal HT therapy in the inflammatory process and the underlying mechanism of CRP activation. More research is needed to understand how HT may be involved in the inflammatory process.

The combination oral and nutritional treatment of late-onset diabetes mellitus (CONTROL DM) trial results.

OBJECTIVE: To examine the effect of short-term improvements in glycaemic control on brachial artery endothelial function as a marker of cardiovascular health. METHODS: Persons with Type 2 diabetes who were poorly controlled on oral therapy were randomly assigned to monotherapy with repaglinide or combination therapy with repaglinide plus metformin. Brachial artery flow-mediated vasodilation was assessed by ultrasonography at randomization and following 16 weeks of therapy. The primary outcome was change in brachial artery endothelial function from baseline. Comparison of randomized groups was a secondary aim. RESULTS: Eighty-six participants were randomized, and 83 were followed to study completion. Post occlusion brachial artery vasodilation was 3.74% at baseline and 3.82% following 16 weeks of therapy (P = 0.77). The treatment effect was 0.08% (95% CI: -0.48%, 0.64%). No difference was seen between treatment groups (P = 0.69). Overall, A1C was reduced from 8.3% to 7.0%, with a greater reduction in the combination therapy group (from 8.4% to 6.7%) than in the monotherapy group (from 8.3% to 7.3%, p for difference between groups = 0.01). Statistically significant reductions were observed in fasting glucose, and plasminogen activator inhibitor-1. Statistically significant increases were observed for fasting insulin, uric acid, weight and BMI. CONCLUSIONS: Brachial artery endothelial function was not influenced by short-term improvements in glycaemic control. The CONTROL DM group was successful in lowering A1C. Future research should explore more intensive and longer-lasting improvements in glycaemic control on endothelial function. Some data previously published in abstract form (Diabetes 2001; 50 (Suppl. 2): A217).

The effects of smoking on estradiol metabolism.

Smoking remains a major health problem especially among women and it influences estrogen metabolism and the risk for multiple estrogen sensitive outcomes. Many indirect effects of smoking exist through the ability of the by-products to modify a variety of drugs, enzymes, and hormones. The results of several in vitro studies have shown that constituents of cigarette smoke have significant effects on production and metabolism of estrogens. In some cases, such as osteoporosis and endometrial cancer, smoking appears to attenuate the effects of estrogen. However, for other outcomes such as breast cancer, venous thromboembolic events (VTE), and coronary heart disease (CHD), the relationship between smoking and estrogen exposure is less defined. Based on the preponderance of evidence, smokers are likely to require higher doses of hormone replacement therapy (HRT) to achieve comparable clinical effect to that observed in nonsmokers. However, uptitrating the dose of HRT in smokers to achieve a desired systemic level or clinical response may simultaneously increase risk for adverse effects that are primarily driven by hepatic rather than systemic exposure. The healthy benefits from smoking cessation should be expressed to women who choose to use HRT, and every effort should be made to encourage them to stop smoking so that they can be effectively treated with the lowest possible dose of HRT.

No effect of HRT on health-related quality of life in postmenopausal women with heart disease.

AIM: Previous clinical studies suggest hormone replacement therapy (HRT) alleviates menopausal symptoms and may improve health-related quality of life (HRQL). Most studies on HRT and HRQL were limited in duration (12 months or less) and scope (few and non-standard HRQL measures). The aim of this paper is to assess HRQL in the Estrogen Replacement and Atherosclerosis (ERA) trial. METHODS: A subset of women within a randomized, blinded, placebo-controlled secondary prevention trial has been studied in outpatient and community settings at 5 US sites. A total of 246 postmenopausal women with angiographically documented heart disease (mean age 66 years, 83% Caucasian) were enrolled in the ERA trial. Participants received either 0.625 mg/day conjugated equine estrogen only, estrogen plus 2.5 mg/day medroxyprogesterone acetate, or placebo. HRQL was assessed using validated questionnaire instruments at baseline and follow-up (mean 3.2 years of trial). Physical and mental functioning, life satisfaction, depressive symptoms, urinary incontinence, sleep disturbance, and frequency and intensity of physical symptoms were evaluated. RESULTS: In this group of women with established coronary disease, active therapy was not significantly associated with more favorable outcomes for any HRQL. The estrogen-only group reported more urinary incontinence than the placebo group (p<0.05). Analyses restricted to adherent women (those who took > or = 80% of pills) showed a similar pattern of results, showing that the estrogen only group reported significantly higher urinary incontinence compared to placebo (p<0.01). CONCLUSION: The hormone replacement regimens in the ERA trial did not improve HRQL of postmenopausal women with heart disease.

Statin therapy in the heart and estrogen/progestin replacement study.

AIM: Limited data exists to guide secondary prevention in postmenopausal women with coronary heart disease (CHD). Treatment with HMG-CoA reductase inhibitors (statins) is likely to be beneficial for these patients. Yet, clinical trial results are conflicting. Moreover, significant interactions may exist between statins and hormone replacement therapy (HRT) that may complicate this approach. METHODS: In a post hoc analysis of the HERS trial, patients who were taking a statin were compared to those who were not. Subjects were randomized to HRT or placebo. Statin therapy was not controlled by the trial investigators, but may have been prescribed by the patients' primary physicians. Use of statins was monitored throughout the trial. The primary outcome was the composite of myocardial infarction and death resulting from CHD, with all-cause mortality and venous thromboembolism (VTE) as secondary outcome measures. RESULTS: At baseline, 1004 subjects were taking a statin, with 1234 subjects randomized to receive HRT, and 1237 to receive placebo. Baseline statin use was associated with lower rates of the primary outcome (MI or fatal CHD, RH=0.78, 95% CI 0.61 to 0.99, p=0.044), and all-cause mortality (RH=0.74, 95% CI 0.56 to 0.99, p=0.04). Statin therapy was associated with a reduced incidence of VTE in both the HRT group and the placebo arm. The negative effect of HRT on the primary outcome seen in the 1st year of treatment was much reduced among baseline statin users and was no longer statistically significant (RH=1.34, 95% CI 0.63 to 2.86, p=0.45). CONCLUSION: Data from HERS supports the use of statins for secondary prevention in postmenopausal women with a history of cardiovascular disease. Statins may attenuate the increased cardiovascular risk of hormone replacement therapy.

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

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

Brachial flow-mediated vasodilator responses in population-based research: methods, reproducibility and effects of age, gender and baseline diameter.

BACKGROUND: Brachial artery ultrasound has been proposed as an inexpensive, accurate way to assess cardiovascular risk in populations. However, analysis and interpretation of these data are not uniform. METHODS: We analysed the relationship between relative and absolute changes in brachial artery diameter in response to flow-mediated dilation and age, gender and baseline diameter among 4,040 ultrasound examinations from subjects aged 14 to 98 years. RESULTS: Reproducibility studies demonstrated intra- and interreader and intrasubject correlations from 0.67 to 0.84 for repeated measures of per cent change in diameter. Per cent change in diameter after flow stimulus was 3.58 +/- 0.10% (mean +/- standard deviation). Corresponding values for baseline diameter and absolute change in diameter were 4.43 +/- 0.87 mm and 0.15 +/- 0.01 mm, respectively. Baseline diameter and its variance were inversely related to per cent change in diameter (P< 0.001). In contrast, absolute change in diameter was more uniform throughout the range of baseline diameters. Baseline diameter was directly related, and per cent change in diameter inversely related, to age (P < 0.001 for all three measures). Time to maximum vasodilator response increased with age (P < 0.001). Women (n=2,315) had significantly larger per cent change in diameter than men (n=1,725) (P < 0.001). However, after adjustment for age and baseline diameter, per cent and absolute change were 5% smaller in women than men (P < 0.05 for both). In multivariate analysis, age was overwhelmingly the most important determinant of absolute change in diameter (P < 0.001). CONCLUSIONS: Automated analysis of brachial flow-mediated vasodilator responses is both feasible and reproducible in large-scale clinical and population-based research.

Invited review: Pharmacogenetics of estrogen replacement therapy.

There are a number of genetic factors that likely modulate both the beneficial and adverse effects of estrogen. An important domain of consideration is the relationship of estrogen and thrombosis risk. Gene polymorphisms among the key elements of the coagulation and fibrinolytic cascade appear to influence the effects of estrogen on risk for venous thromboembolic events and possibly arterial thrombosis as well. Emerging data also suggest that allelic variants in the estrogen receptor-alpha may modulate estrogen's effects, especially with respect to bone and lipid metabolism.

Differential effects of E and droloxifene on C-reactive protein and other markers of inflammation in healthy postmenopausal women.

Although increased levels of C-reactive protein have been linked to E therapy, the significance of this finding and whether it occurs with the selective ER modulators are unknown. Thirty-five healthy postmenopausal women were enrolled in a placebo-controlled, two-period cross-over design trial to evaluate the effects of 0.625 mg oral conjugated E and 60 mg droloxifene, a structural analog of tamoxifen, on serum levels of C-reactive protein, IL-6, and endothelial cell adhesion molecules. E treatment resulted in 65.8% higher levels of C-reactive protein (P = 0.0002) and 48.1% higher levels of IL-6 (P < 0.001), but also resulted in a 10.9% reduction in soluble E-selectin (P = 0.002) and borderline reductions in vascular cell adhesion molecule-1. In contrast, droloxifene had no effect on C-reactive protein and IL-6, but did produce a significant 11% reduction in E-selectin (P < 0.00001). However, droloxifene also resulted in an 11.6% increase in vascular cell adhesion molecule-1 (P < 0.007). These data provide additional evidence of a proinflammatory effect of E that may have adverse cardiovascular consequences. However, these changes were also accompanied by a reduction in E-selectin, suggesting an antiinflammatory effect at the level of the endothelium. The net clinical impact of these changes is not yet well established. In contrast, droloxifene had little or no proinflammatory effects on C-reactive protein and IL-6 and had mixed effects on endothelial adhesion molecules. This observation provides additional rationale for continuing to evaluate the potential cardiovascular benefits of selective ER modulators.