Sex differences in susceptibility to etiologic factors for peripheral atherosclerosis. Importance of plasma fibrinogen and blood viscosity

Ankle-Brachial Index and Subsequent Risk of Severe Ischemic Leg Outcomes: The ARIC Study

Background Ankle-brachial index (ABI) is used to identify lower-extremity peripheral artery disease (PAD). However, its association with severe ischemic leg outcomes (eg, amputation) has not been investigated in the general population. Methods and Results Among 13 735 ARIC (Atherosclerosis Risk in Communities) study participants without clinical manifestations of PAD (mean age, 54 [SD, 5.8] years; 44.4% men; and 73.6% White) at baseline (1987-1989), we quantified the prospective association between ABI and subsequent severe ischemic leg outcomes, critical limb ischemia (PAD with rest pain or tissue loss) and ischemic leg amputation (PAD requiring amputation) according to discharge diagnosis. Over a median follow-up of ≈28 years, there were 221 and 129 events of critical limb ischemia and ischemic leg amputation, respectively. After adjusting for demographics, ABI ≤0.90 versus 1.11 to 1.20 had a ≈4-fold higher risk of critical limb ischemia and ischemic leg amputation (hazard ratios, 3.85 [95% CI, 2.09-7.11] and 4.39 [95% CI, 2.08-9.27]). The magnitude of the association was modestly attenuated after multivariable adjustment (hazard ratios, 2.44 [95% CI, 1.29-4.61] and 2.72 [95% CI, 1.25-5.91], respectively). ABI 0.91 to 1.00 and 1.01 to 1.10 were also associated with these severe leg outcomes, with hazard ratios ranging from 1.7 to 2.0 after accounting for potential clinical and demographic confounders. The associations were largely consistent across various subgroups. Conclusions In a middle-aged community-based cohort, lower ABI was independently and robustly associated with increased risk of severe ischemic leg outcomes. Our results further support ABI ≤0.90 as a threshold diagnosing PAD and also suggest the importance of recognizing the prognostic value of ABI 0.91 to 1.10 for limb prognosis.

Sex and light physical activity impact popliteal, but not brachial artery flow-mediated dilation in physically active young adults

When controlling for baseline diameter, males have greater brachial flow-mediated dilation (BA-FMD) responses than females. It is unclear whether sex differences in baseline diameter also influences popliteal FMD (POP-FMD), which may be impacted by cardiorespiratory fitness and physical activity levels. We hypothesized that males would exhibit greater BA-FMD and POP-FMD when allometrically scaled to baseline diameter. FMD (ultrasonography), cardiorespiratory fitness (indirect calorimetry), and objectively measured physical activity were assessed in males (n = 13; age, 23 ± 3 years; peak oxygen consumption, 48.0 ± 7.1 mL·kg^-1·min^-1) and females (n = 13; age, 24 ± 2 years; peak oxygen consumption, 36.8 ± 6.0 mL·kg^-1·min^-1). Both groups had similarly high levels of moderate-to-vigorous intensity physical activity (503 ± 174 vs. 430 ± 142 min·week^-1, p = 0.25). However, males were more aerobically fit (p < 0.001) and females accumulated more light-intensity physical activity (182 ± 67 vs. 127 ± 53 min·week^-1, p = 0.03). Relative and allometrically scaled BA-FMD were similar (both, p ≥ 0.09) between sexes. In contrast, relative (6.2% ± 1.0% vs. 4.6% ± 1.4%, p = 0.001) and scaled (6.8% ± 1.7% vs. 4.7% ± 1.7%, p = 0.03) POP-FMD were greater in females. Relative POP-FMD was related to light-intensity physical activity in the pooled sample (r = 0.43; p = 0.04). However, the enhanced relative POP-FMD in females remained after adjusting for higher light-intensity physical activity levels (p = 0.01). Young females have enhanced popliteal, but not brachial, endothelial health than males with similar moderate-to-vigorous intensity physical activity levels and higher cardiorespiratory fitness. Novelty In physically active adults, females had greater POP-FMD but not BA-FMD than males. The enhanced POP-FMD in females was not related to greater vascular smooth muscle sensitivity to nitric oxide or their smaller baseline diameters. POP-FMD was associated with light physical activity levels in the pooled sample.

Hemorheological abnormalities and their associations with coronary blood flow in patients with cardiac syndrome X: a comparison between males and females

Aim:

The role of elevated whole blood viscosity (WBV) in the pathogenesis of atherosclerosis is well known. We sought to investigate the gender differences in the association between WBV, coronary blood flow and tissue oxygen delivery index (TODI) in cardiac syndrome X (CSX).

Methods:

Forty-six CSX patients and 14 healthy volunteers were enrolled. The coronary flow parameters were obtained with transthoracic Doppler echocardiography and WBV was measured (at high-shear and low-shear rates of 300s-1 and 5s-1, respectively) using a scanning capillary tube viscometer. TODI was determined from the ratio of hematocrit to WBV measured at a low-shear rate of 5s-1.

Results:

In male patients, the mean diastolic coronary flow velocity (CFV) and diastolic velocity time integral (VTI) were significantly decreased compared to control group (all p<0.05) and the WBV showed significant negative correlation with peak systolic CFV (r = −0.559 at 300s-1, r = −0.438 at 5s-1), mean systolic CFV (r = −0.577 at 300s-1, r = −0.488 at 5s-1), systolic VTI (r = −0.576 at 300s-1, r = −0.530 at 5s-1) and diastolic VTI (r = −0.553 at 300s-1, r = −0.551 at 5s-1) (all p<0.01). Meanwhile, although female patients showed no significant relationships between WBV and coronary flow parameters, TODI were significantly decreased compared to the control group (3.64 ± 0.34 vs. 4.07 ± 0.38%/centipoises (cP), respectively, p=0.008).

Conclusion:

Our study suggests that there are gender-related differences in the pathogenesis of microvascular angina and gender-specific approaches for CSX patients might be needed.

Hybrid System for Ex Vivo Hemorheological and Hemodynamic Analysis: A Feasibility Study

Precise measurement of biophysical properties is important to understand the relation between these properties and the outbreak of cardiovascular diseases (CVDs). However, a systematic measurement for these biophysical parameters under in vivo conditions is nearly impossible because of complex vessel shape and limited practicality. In vitro measurements can provide more biophysical information, but in vitro exposure changes hemorheological properties. In this study, a hybrid system composed of an ultrasound system and microfluidic device is proposed for monitoring hemorheological and hemodynamic properties under more reasonable experimental conditions. Biophysical properties including RBC aggregation, viscosity, velocity, and pressure of blood flows are simultaneously measured under various conditions to demonstrate the feasibility and performance of this measurement system. The proposed technique is applied to a rat extracorporeal loop which connects the aorta and jugular vein directly. As a result, the proposed system is found to measure biophysical parameters reasonably without blood collection from the rat and provided more detailed information. This hybrid system, combining ultrasound imaging and microfluidic techniques to ex vivo animal models, would be useful for monitoring the variations of biophysical properties induced by chemical agents. It can be used to understand the relation between biophysical parameters and CVDs.

Gender differences and disparities in all-cause and coronary heart disease mortality: epidemiological aspects

This overview is primarily concerned with large recent prospective cohort studies of adult populations, not patients, because the latter studies are confounded by differences in medical and surgical management for men vs. women. When early papers are uniquely informative they are also included. Because the focus is on epidemiology, details of age, sex, sample size, and source as well as study methods are provided. Usually the primary outcomes were all-cause or coronary heart disease (CHD) mortality using baseline data from midlife or older adults. Fifty years ago few prospective cohort studies of all-cause or CHD mortality included women. Most epidemiologic studies that included community-dwelling adults did not include both sexes and still do not report men and women separately. Few studies consider both sex (biology) and gender (behavior and environment) differences. Lifespan studies describing survival after live birth are not considered here. The important effects of prenatal and early childhood biologic and behavioral factors on adult mortality are beyond the scope of this review. Clinical trials are not discussed. Overall, presumptive evidence for causality was equivalent for psychosocial and biological exposures, and these attributes were often associated with each other. Inconsistencies or gaps were particularly obvious for studies of sex or gender differences in age and optimal measures of body size for CHD outcomes, and in the striking interface of diabetes and people with the metabolic syndrome, most of whom have unrecognized diabetes.

Preparation of Chitosan and Water-Soluble Chitosan Microspheres via Spray-Drying Method to Lower Blood Lipids in Rats Fed with High-Fat Diets

This experiment aimed to investigate the effects of the chitosan (CTS) and water-soluble chitosan (WSC) microspheres on plasma lipids in male Sprague-Dawley rats fed with high-fat diets. CTS microspheres and WSC microspheres were prepared by the spray-drying technique. Scanning electron microscopy (SEM) micrographs showed that the microspheres were nearly spherical in shape. The mean size of CTS microspheres was 4.07 μm (varying from 1.50 to 7.21 μm) and of WSC microspheres was 2.00 μm (varying from 0.85 to 3.58 μm). The rats were classified into eight groups (n = 8) and were fed with high-fat diets for two weeks to establish the hyperlipidemic condition and were then treated with CTS microspheres and WSC microspheres, CTS and WSC for four weeks. The results showed that CTS and WSC microspheres reduced blood lipids and plasma viscosity and increased the serum superoxide dismutase (SOD) levels significantly. This study is the first report of the lipid-lowering effects of CTS and WSC microspheres. CTS and WSC microspheres were found to be more effective in improving hyperlipidemia in rats than common CTS and WSC.

Importance of blood rheology in the pathophysiology of atherothrombosis

Elevated blood viscosity is an integral component of vascular shear stress that contributes to the site specificity of atherogenesis, rapid growth of atherosclerotic lesions, and increases their propensity to rupture. Ex vivo measurements of whole blood viscosity (WBV) is a predictor of cardiovascular events in apparently healthy individuals and studies of cardiovascular disease patients. The association of an elevated WBV and incident cardiovascular events remains significant in multivariate models that adjust for major cardiovascular risk factors. These prospective data suggest that measurement of WBV may be valuable as part of routine cardiovascular profiling, thereby potentially useful data for risk stratification and therapeutic interventions. The recent development of a high throughput blood viscometer, which is capable of rapidly performing blood viscosity measurements across 10,000 shear rates using a single blood sample, enables the assessment of blood flow characteristics in different regions of the circulatory system and opens new opportunities for detecting and monitoring cardiovascular diseases.

Association between periodontal disease and ischemic heart disease among Swedish women: a cross-sectional study

OBJECTIVE

The aim of this cross-sectional study was to analyze the relationship between chronic periodontitis and ischemic heart disease (IHD).

MATERIAL AND METHODS

A cross-section of women aged 38 to 84 years were examined in 1992-93 (analysis based on n=1056). Medical and dental examinations were included in the analysis specifically with regard to IHD and periodontitis. Other well-known risk factors for IHD were used as covariates in multivariable statistical analysis.

RESULTS

Among the dentate women in this study (n=847), 74 had IHD and 773 did not. There was no statistically significant difference between numbers of pathological gingival pockets between these groups (58.1% had one or more pathological pockets in the IHD group compared to 57.6% in the non-IHD group). Bivariate analysis of dentate individuals showed significant associations between IHD and number of missing teeth, age, body mass index, waist/hip ratio, life satisfaction, hypertension, and levels of cholesterol and triglycerides. However, in the final multivariable logistic regression model, with the exception of age, only number of teeth (<17 teeth) OR = 2.13 (CI 1.20; 3.77) was found to be significantly associated with IHD. Moreover, edentulous women had an OR of 1.94 (CI 1.05; 3.60) in relation to IHD (age-adjusted model).

CONCLUSIONS

In the present study, periodontitis did not seem to have a statistically significant relationship with IHD. The number of missing teeth showed a strong association with IHD, and this may act as a proxy variable tapping an array of different risk factors and behaviors.

The reliability of the ankle-brachial index in the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS)

Background

A low ankle-brachial index (ABI) is associated with increased risk of coronary heart disease, stroke, and death. Regression model parameter estimates may be biased due to measurement error when the ABI is included as a predictor in regression models, but may be corrected if the reliability coefficient, R, is known. The R for the ABI computed from DINAMAP™ readings of the ankle and brachial SBP is not known.

Methods

A total of 119 participants in both the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS) had repeat ABIs taken within 1 year, using a common protocol, automated oscillometric blood pressure measurement devices, and technician pool.

Results

The estimated reliability coefficient for the ankle systolic blood pressure (SBP) was 0.68 (95% CI: 0.57, 0.77) and for the brachial SBP was 0.74 (95% CI: 0.62, 0.83). The reliability for the ABI based on single ankle and arm SBPs was 0.61 (95% CI: 0.50, 0.70) and the reliability of the ABI computed as the ratio of the average of two ankle SBPs to two arm SBPs was estimated from simulated data as 0.70.

Conclusion

These reliability estimates may be used to obtain unbiased parameter estimates if the ABI is included in regression models. Our results suggest the need for repeated measures of the ABI in clinical practice, preferably within visits and also over time, before diagnosing peripheral artery disease and before making therapeutic decisions.

Lower extremity arterial disease assessed by ankle-brachial index in a middle-aged population of African Americans and whites: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Lower extremity arterial disease (LEAD) is one of the most common manifestations of atherosclerosis. Its epidemiologic characteristics have not been well described, particularly in African Americans. Our purpose was to estimate the prevalence of LEAD and its associations with cardiovascular risk factors in a biracial population of men and women aged 45 to 64 years.

METHODS

We examined 15,173 African-American and white men and women who participated in the baseline examination (1987-1989) of the Atherosclerosis Risk in Communities (ARIC) Study. LEAD was defined by a resting ankle-brachial index (ABI), the ratio of ankle systolic blood pressure to brachial systolic pressure, of < or = 0.90. Cross-sectional analyses were used to determine the association of LEAD with cardiovascular risk factors.

RESULTS

The age-adjusted prevalence of ABI < or = 0.90 was 3.1% in African-American men, 4.4% in African-American women, 2.3% in white men, and 3.2% in white women. Cigarette smoking was the single most important risk factor for prevalent LEAD. The odds ratio estimate for LEAD in ever smokers versus never smokers was 6.6 (95% confidence interval [CI]=2.0-21.5) in African-American men, 2.3 (95% CI=1.5-3.5) in African-American women, 10.4 (95% CI=3.8-28.3) in white men, and 1.9 (95% CI=1.4-2.6) in white women, after adjustment for age, LDL cholesterol, hypertension, and diabetes. Prevalent LEAD was also associated with hypertension, diabetes, and higher concentrations of total cholesterol, triglycerides, LDL-cholesterol, and fibrinogen, and lower concentrations of HDL cholesterol, but the associations were not always significant across race/ethnic and gender groups. The associations of LEAD with plasma lipids were generally stronger in African Americans than whites.

CONCLUSIONS

The prevalence of LEAD appears to be higher in African Americans than whites. Elevations in traditional cardiovascular risk factors are associated with a higher prevalence of LEAD across race/ethnic and gender groups.

Association of hyperviscosity and subclinical atherosclerosis in obese schoolchildren

Since December 2001, a total of 52 obese schoolchildren and 38 non-obese controls have undergone vascular ultrasound at our institution. From this cohort, we enrolled 40 obese children (16 girls, median age 12 years, mean body mass index (BMI) 27.5+/-4.6 kg/m2) and 26 non-obese peers (12 girls, median age 12 years, mean BMI 16.1+/-2.4 kg/m2) for the present study. We analysed the association between obesity, subclinical atherosclerosis and haemorheological variables, including whole blood viscosity (WBV) at four different shear rates (200 s-1, 30 s-1, 5 s-1 and 1 s-1), plasma viscosity, and serum lipid concentrations. Blood lipids and apolipoproteins were also determined and correlated with carotid intima-media thickness (IMT) and flow-mediated dilatation (FMD) of the brachial artery, measured by high-resolution ultrasonography. WBV at 200 s-1, 30 s-1 and 5 s-1, as well as plasma viscosity, were significantly higher in the obesity group (all P <0.01). No difference was seen for WBV at 1 s-1, erythrocyte aggregation and haematocrit. WBV at high shear rates was significantly associated with BMI, increased IMT and decreased FMD ( P <0.05). After controlling for BMI on stepwise linear regression, WBV at 30 s-1 was the strongest predictor of IMT ( P < 0.01) and FMD ( P < 0.05) among our study variables.

CONCLUSION

Hyperviscosity is related to subclinical atherosclerosis in obese schoolchildren. Viscosity parameters contribute new information in addition to body mass index, blood pressure and blood lipids and may help to facilitate risk stratification in obese paediatric patients.

Oral health in women with coronary heart disease

BACKGROUND

Over the last few decades, oral diseases including periodontitis, have been discussed as a possible risk factor for cardiovascular disease. The purpose of this study was to compare the oral health of age-matched women with or without coronary heart disease (CHD).

METHODS

A total of 143 consecutive women, aged 43 to 79 years, with diagnosed CHD underwent a thorough dental examination including a panoramic radiograph and were compared to 50 women, aged 45 to 77 years without CHD.

RESULTS

The number of remaining teeth and pathological periodontal pockets (> or =4 mm) between the groups differed. The women with CHD had 18.9 +/- 8.5 remaining teeth versus 23.4 +/- 6.3 teeth in the control group (P < 0.001). The CHD group had more pathological periodontal pockets compared to the controls, 14.2 +/- 12.4 versus 9.6 +/- 13.3 (P = 0.002), respectively. The mean marginal bone level assessed on radiographs was the same in both groups, while the number of vertical bone defects differed (P = 0.022). Dentures were more frequent in the CHD group than in the controls (27% versus 6%, P = 0.022), as was edentulousness, 10.5% versus 0% (P = 0.017), respectively. Multiple regression analysis adjusted for age, smoking, body mass index (BMI), diabetes, education, and place of birth showed a relation between the number of periodontal pockets and CHD with an odds ratio (OR) of 3.8 (1.68 to 8.74), and a tendency between dentures and CHD, with an OR of 4.6 (0.99 to 21.28).

CONCLUSION

This study indicates that women with CHD have worse oral health than those in a comparable group with no history of CHD.

The Influence of Flow, Vessel Diameter, and Non-Newtonian Blood Viscosity on the Wall Shear Stress in a Carotid Bifurcation Model for Unsteady Flow

OBJECTIVES

The atherosclerotic process in arteries is correlated with the local wall shear stress (WSS). Plaque development particularly occurs in regions with recirculation (ie, where the WSS oscillates). We investigated the effects of non-Newtonian blood viscosity, variations in flow rate, and vessel diameter on wall phenomena in a carotid bifurcation model.

MATERIALS AND METHODS

The flow through a model of a carotid artery bifurcation was simulated by means of the finite element method. The whole-blood viscosity is a function of shear rate, and was modeled by the Carreau-Yasuda (CY) model. Flow rate and vessel morphology were assessed with magnetic resonance imaging. Flow rate, blood viscosity, and hematocrit levels (Hct) were measured in 49 healthy volunteers. We propose an adaptation of the CY model so that differences in Hct can be incorporated; furthermore, plasma viscosity was varied in the CY model.

RESULTS

The data from our model indicate that flow increases have a larger effect on the WSS than predicted with a simple paraboloid model. Hct had more influence on the WSS when the plasma viscosity was low. Low plasma viscosity was associated with a low WSS, which implies a contradiction, because both high WSS and low plasma viscosity are thought to be indicators for a healthy system. Maximum WSS oscillations were found at the edges of the recirculation region.

CONCLUSIONS

Flow and diameter changes have significant influence on wall shear stress values; the same is true for the viscosity, but to a lesser extent.

–455G/A β-fibrinogen gene polymorphism, factor V Leiden, prothrombin G20210A mutation and MTHFR C677T, and placental vascular complications

Hyperfibrinogenaemia is associated with systemic arterial and venous thromboembolism and therefore may contribute to placental vascular disease associated with obstetric complications. The fibrinogen-raising -455G/A beta-fibrinogen gene polymorphism may enhance the physiological increase in fibrinogen levels during pregnancy and thereby predispose to obstetric complications. This retrospective case-control study looked at the association between the beta-fibrinogen gene polymorphism -455G/A, the hereditary thrombophilic markers factor V Leiden, prothrombin G20210A mutation (PGM) and C677T methylene tetrahydrofolate reductase (MTHFR), and obstetric complications associated with placental vascular disease. The study group (n = 247) comprised 147 women (90 Caucasian) who met the clinical criteria and a control group of 100 parous women (90 Caucasian) with no history of obstetric or medical complications. No significant differences were observed in the -455A allelic frequencies of the patient and normal control groups, with (allelic frequencies, 0.156 and 0.178, respectively; P = 0.5716, chi2 test, odds ratio = 1.17, 95% confidence interval = 0.65-2.13) or without (allelic frequencies, 0.129 and 0.170, respectively; P = 0.2077, chi2 test, odds ratio = 1.38, 95% confidence interval = 0.81-2.35) the exclusion of non-Caucasian women. There was an increased prevalence of factor V Leiden among Caucasian patients compared with normal controls (allelic frequencies, 0.056 and 0.017, respectively; P = 0.048, chi2 test, odds ratio = 0.29, 95% confidence interval = 0.05-1.15) but there were no differences in the prevalences of PGM or MTHFR. These data suggest that factor V Leiden is associated with an increased risk of obstetric complications, but that the -455A allele of beta-fibrinogen, PGM and MTHFR do not appear to be implicated.

Hematocrit is associated with carotid atherosclerosis in men but not in women

BACKGROUND

It is known that blood and plasma viscosities are associated with clinical manifestations of atherosclerosis, though evidence is not conclusive particularly in women.

OBJECTIVE

To verify whether hematocrit and blood and plasma viscosities are independently associated with carotid atherosclerosis and whether their measurement can improve the definition of the global coronary heart disease (CHD) risk.

METHOD

Eight hundred and ninety-two participants in a cardiovascular disease prevention campaign were examined with regard to conventional CHD risk factors (age, blood pressure, lipids, glucose, body mass index, waist/hip ratio, cigarette smoking and diabetes), hematocrit and blood and plasma viscosities. According to the degree of carotid atherosclerosis, investigated by echo-Doppler, participants were divided in three groups: those without atherosclerosis, those with a low degree of atherosclerosis and those with a high degree of atherosclerosis.

RESULTS

In men, age, blood pressure, intima-media thickness (IMT), hematocrit (47.4+/-3.7%, 47.8+/-3.7%, 48.4+/-3.7%, P<0.05) and blood viscosity (4.69+/-0.51 cP, 4.77+/-0.55 cP, 4.82+/-0.51 cP, P=0.05) increased with increasing degree of carotid atherosclerosis. In women, age, blood pressure, total cholesterol and low-density lipoprotein-cholesterol, IMT and plasma viscosity (1.42+/-0.12 cP, 1.44+/-0.11 cP, 1.46+/-0.13 cP, P<0.05) increased with increasing carotid score. Analysis of covariance (ANCOVA) showed that after adjusting for hematocrit, blood viscosity was no longer different in the three groups. In discriminant analysis, hematocrit, among the hemorheological variables investigated, was independently associated with carotid score in men (F=3.66, P<0.05). Neither hematocrit nor blood and plasma viscosities were significantly associated with carotid score in women.

CONCLUSION

These findings suggest that in men, both hematocrit and blood viscosity are related to carotid atherosclerosis but hematocrit would appear to have an independent effect over and above that mediated by viscosity.

Contribution of contemporaneous risk factors to social inequality in coronary heart disease and all causes mortality

BACKGROUND

The relationship between low social status and premature mortality is well established, although the explanation for this link is unclear. This study explores the contribution to the social inequalities in coronary heart disease (CHD) and death of smoking status, cotinine, alcohol status, type A personality score, leisure activity, diabetes, systolic and diastolic blood pressure, body mass index, total and HDL cholesterol, triglycerides, fibrinogen, and vitamin C consumption.

METHODS

A random sample of 11,629 Scottish men and women, ages 40-59 years, was recruited in 1984-1987 and followed up for an average of 7.7 years for death and major coronary events. Social status was measured by housing tenure--renters being more socially deprived. Hazard ratios were computed from Cox models.

RESULTS

Adjusted for age, renters have 1.48 times the risk of CHD compared to owner-occupants (95% CI: 1.21, 1.80) in men and 2.64 (1.89, 3.68) in women, and for all-cause mortality 1.55 (1.26, 1.90) and 2.12 (1.58, 2.84). The 14 risk factors explained 73% (men) and 77% (women) of the social differences in CHD. Equivalent figures for deaths were 51 and 64%.

CONCLUSIONS

Fourteen contemporaneous risk factors, smoking being the most important, explain most of the social differential in CHD and death.

Hematocrit and the risk of coronary heart disease mortality

BACKGROUND

An association between hematocrit (Hct) and coronary heart disease (CHD) mortality has been previously observed. However, the relationship of Hct and CHD independent of other cardiovascular disease (CVD) risk factors and differences between men and women remain unclear.

METHODS

We examined the association between Hct and CHD mortality with Cox regression analyses of data from 8896 adults, aged 30-75 years, in the Second National Health and Nutrition Examination Survey (NHANES II) Mortality Study (1976-1992). Covariates included age, sex, race, education, smoking status, hypertensive status, total serum cholesterol, body mass index, white blood cell count, and history of CVD and diabetes. Hct was categorized by use of sex-specific tertiles, and all analyses were stratified by sex.

RESULTS

During 16.8 years of follow-up, there were 545 (men 343, women 202) deaths from CHD (International Classification of Diseases, 9th revision [ICD-9] 410-414), 778 (men 426, women 279) deaths from diseases of the heart (ICD-9 390-398, 402, 404, 410-414, 415-417, 420-429), and 2046 (men 1216, women 830) all-cause deaths. Among men, the crude CHD mortality rate per 10,000 population was 42.6, 31.9, and 46.3 among those with Hct in the lower, middle, and upper tertiles, respectively. The corresponding crude CHD mortality rates among women were 12.6, 18.6, and 27.7. After adjustment for age and other CVD risk factors, there was no association between Hct in the upper tertile compared with the lower tertile and mortality from either CHD, diseases of the heart, or all causes among men. Women with Hct in the upper tertile were 1.3 times (95% CI 0.9-1.9) more likely to die from CHD than were women with Hct in the lowest tertile, after multivariate adjustment. The effect of high Hct on CHD mortality among women younger than 65 years of age was slightly stronger (relative risk 2.2, 95% CI 1.0-4.6).

CONCLUSIONS

These results suggest that the association between Hct and mortality from CHD and all causes is complex, differing both by sex and age. Further research is needed to gain a better understanding of these age and sex differences.

Smoking, other risk factors and fibrinogen levels. evidence of effect modification

PURPOSE

Recent investigations have indicated that smoking may act as an important modifier of the risk associated with dyslipidemia. We hypothesized as a potential mechanism that smoking modifies the association between traditional risk factors of early atherosclerosis, such as dyslipidemia, hypertension, or diabetes, with fibrinogen, a risk factor more closely related to plaque progression and thrombosis.

METHODS

The sample for this cross-sectional study, was collected from the MONICA Augsburg population survey of 1989/90 and included 1840 men and 1784 women, aged 25 to 64 years. Traditional risk factors hypertension, diabetes mellitus, and dyslipidemia were assessed by personal interviews, and medical examinations. Plasma fibrinogen concentration was determined by nephelometry. Effect modification was assessed by stratified analyses and tests for statistical interaction.

RESULTS

Fibrinogen levels were higher in women than in men and, after adjustment for potential confounders, higher in smokers than in nonsmokers (each p < 0.001). The effect of smoking was greater in men (p < 0.001). The elevation of mean adjusted fibrinogen levels associated with hypertension or with diabetes in men was significantly higher in smokers as compared to nonsmokers (test for interaction, p < 0.001). By contrast, smoking in women showed significantly stronger impacts only with regard to the association of dyslipidemia and fibrinogen (p < 0.001). Comparing groups of subjects with increasing numbers of concomitant risk factors, stratified according to their smoking status, effect modification by smoking was particularly evident in male participants with two or more risk factors. Numbers of women with more than one risk factor and smoking were too low for analysis.

CONCLUSIONS

We demonstrate that smoking contributes more than additively to the strong influences of single and combined traditional risk factors on fibrinogen levels. These data confirm that smoking is a dominant determinant of fibrinogen levels in the general population.

Age and sex differences in the relationship between inherited and lifestyle risk factors and subclinical carotid atherosclerosis: the Tromsø study

BACKGROUND

Ultrasound measurement of carotid artery intima-media thickness (IMT) is regarded as a valid index of atherosclerosis. Age and sex differences in the distribution of, and risk factors for, IMT have not been investigated thoroughly.

METHODS

In 1994-1995 a total of 6408 men and women aged 25-84 years living in the municipality of Tromsø, Norway, underwent ultrasound examination of carotid artery IMT and measurements of cardiovascular risk factors.

RESULTS

Age, systolic blood pressure, total cholesterol, HDL cholesterol, body mass index, and smoking were independent predictors of IMT in both sexes. Fibrinogen levels and physical activity were associated with IMT in men only, whereas triglyceride levels were associated with IMT independently of HDL cholesterol in women only. A family history of cardiovascular disease (CVD) was an independent predictor of IMT in both sexes, also when controlling for traditional CVD risk factors. The magnitude of the association between most risk factors and IMT did not differ depending on age, but the effects of physical activity and triglycerides were more pronounced at higher age.

CONCLUSION

These data suggest that there are significant age and sex differences in the distribution and the determinants of subclinical atherosclerosis.

Antithrombotic therapy in gynecologic surgery and gynecologic oncology

The European Consensus Conference has assessed the risk for thrombotic complications for most women undergoing gynecologic surgery and found it to be moderate. Nonetheless, it is important to analyze a patient's individual risk before surgery so that appropriate thrombosis prophylaxis can be given if increased risk is determined. Malignancy accounts for most thrombotic complications among gynecologic patients. Patients with known malignancies should receive prophylaxis during surgery, and some patients with breast cancer should receive prophylaxis during chemotherapy. Heparin, and low-molecular-weight heparin in particular, may favorably influence the outcome of cancer in some patients and treatment with these agents is currently under investigation in a number of trials as a new approach to anticancer therapy.

Hemostatic Factors and Ischemic Heart Disease Risk Among Postmenopausal Women

The following is a review of (largely) epidemiologic evidence on whether changes in plasma hemostatic concentrations occur with menopause and with postmenopausal hormone therapy which may have an impact on risk of ischemic heart disease. To date, only plasma fibrinogen has been positively associated with long-term risk of disease among women; however, data are sparse. Taken together, the evidence supports an impact of endogenous sex hormone levels on thrombotic potential and points to a modest increase in a number of plasma hemostatic factor levels at menopause. Results of studies of estrogen therapy are somewhat conflicting. Observational findings suggest that, except for possibly the Factor VII level, estrogen therapy may prevent the menopause-related rise in plasma hemostatic factors. In contrast, controlled experiments have found increased markers of thrombin generation with use of common formulations of estrogen therapy. The hemostatic effects found with oral preparations do not appear to occur with transdermal forms of estrogen although data are limited. Overall, the evidence shows menopause to have an impact on plasma levels of hemostatic factors which appears to be modified by use of oral estrogen. Whether these alterations in plasma levels have an impact on risk of ischemic heart disease among postmenopausal women remains to be demonstrated.

Rheological influences on thrombosis

Blood flow plays important roles in the localization and morphology of thrombosis within the circulation. Blood flow properties (rheological variables) are associated with thrombotic risk factors and thrombotic risk; conversely their modification may reduce thrombotic risk.

[Cardiovascular risk in menopause: myth, paradox or reality. The importance of clinical observations vs statistical data interpretation]

Coronary mortality among men is higher than in women in all age groups. Women seem to be protected from coronary disease. After the age of 50, coronary mortality increases fast in women and slows down in men, so that the mortality curves tend to join at some level. This fact led to believe that menopause had some influence over the non-proportional increase of coronary risk in women. Estrogens would be responsible for this protection before menopause and their further decrease would be the cause of higher coronary mortality. Mortality rate data, taken from a population with a high rate disease or a low rate disease, do not prove the above statement. For this reason it is said to by a myth. If it were a myth, then to try to prevent by administrating a substitute of these estrogens during menopause would be a paradox. If we accept that coronary atherosclerosis disease has many etiological factors, we should conclude that, besides hormones, there are other elements involved. The kind of personality, the way of life together with genetic factors related to gender would explain differences in frequency and mortality due to coronary heart disease, which, in this case, clearly advocates for women.

Chemotherapy and thrombosis in gynecologic malignancy

Thromboembolism is a severe and frequent problem in gynecologic malignancy. The average DVT incidence during chemotherapy of 5% might represent the lower range of incidence because < 55% of thrombotic complication manifest clinical signs. However, it seems likely that in addition to chemotherapy other risk factors such as menopausal status, BMI of patients, or type of preceding surgery must coincide before thrombosis manifests. While monitoring of patients using sophisticated coagulation tests did not identify patients' risk for DVT during chemotherapy, an evaluation of the coagulation status before initiating chemotherapy is recommended. Patients with a venous access device (e.g., indwelling central venous catheter or with port cart) are at a particularly high risk for DVT. This has to be considered when cytoreductive therapy is given. Thrombosis prophylaxis, orally or subcutaneously, should only be considered in a subpopulation of patients who offer a combination of the aforementioned risk factors. Thrombosis prevention trials during chemotherapy found a significant reduction of DVT in patients treated with anticoagulants.

Plasma fibrinogen and incident hypertension in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Several cross-sectional studies have reported a positive association between plasma fibrinogen levels and prevalent hypertension. Other studies have reported a positive association between hypertension and whole-blood or plasma viscosity, to which fibrinogen contributes. To our knowledge, there has been no prospective study of fibrinogen and incident hypertension.

SUBJECTS AND METHODS

We measured plasma fibrinogen levels in a population-based cohort study of middle-aged adults and related it to the occurrence of incident hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg or use of antihypertensive medication) over 6 years.

RESULTS

There was a moderately strong positive association between fibrinogen levels and prevalent hypertension in both men and women, with the odds of hypertension elevated by 50% for the highest fibrinogen quartile versus the lowest. Among 7884 participants at risk, 1609 developed hypertension over 6 years. Adjusted for age, race, field center and baseline systolic blood pressure, the odds ratio of incident hypertension in relation to fibrinogen quartiles was 1.0, 1.07, 1.21 and 1.43 in men (P= 0.003 for trend) and 1.0, 0.92, 0.99 and 0.99 in women (P= 0.89 for trend). After adjustment for other risk factors, the odds ratios were 1.0, 1.03, 1.15 and 1.29 (P= 0.045 for trend) in men and remained nonsignificant in women.

CONCLUSIONS

Despite a moderately strong positive association between fibrinogen levels and prevalent hypertension in both sexes, there was only a weak positive association between fibrinogen levels and incident hypertension in men and no association in women. Whether an elevated fibrinogen level is a risk factor for, or a consequence of, hypertension remains unclear.

Fibrinogen and albuminuria are related to the presence and severity of peripheral arterial disease in women with type 2 diabetes mellitus

The relationship between the ultrasonographically determined presence and severity of peripheral arterial disease (PAD) and cardiovascular risk factors was studied in 30 post-menopausal, nonsmoking women with type 2 diabetes mellitus. PAD was established on the basis of decreased ankle/arm index (AAI) of < 0.9 in 15 patients. The control group included 15 type 2 diabetic women with AAI > 1.0. There were no differences with respect to diabetes control and systolic blood pressure between the patients with PAD and controls. The patients with PAD had significantly higher mean fibrinogen concentrations (4.75 +/- 0.35 vs 3.53 +/- 0.36 g/L, P < 0.01) and urinary albumin excretion (UAE) values (893 +/- 501 vs 57 +/- 24 mg/day, P < 0.05) than the subjects in the control group. There was no significant difference between the study groups with respect to any lipid variables. Significant partial correlations adjusted for age were observed between AAI (which expressed the severity of PAD) and log UAE (r = -0.55, P < 0.01), creatinine (r = -0.48, P < 0.01) and fibrinogen (r = -0.45, P < 0.01). In the multiple stepwise regression analysis with AAI as a dependent variable, only fibrinogen (P = 0.033) and log UAE (P = 0.029) were included into the best model. In conclusion, in nonsmoking women with type 2 diabetes mellitus, fibrinogen and albuminuria were the only risk factors associated with both the presence and severity of peripheral arterial disease.

Hemorrheological indices, catecholamines, neuropeptide Y and serotonin in patients with essential hypertension

Hemorrheological and humoral abnormalities and excessive platelet activity can predict the development of cardiovascular complications in patients with essential hypertension. A study was conducted to assess the influence of gender on these factors and the interrelations between changes in hemorrheology and the sympatho-adrenal system in 54 patients (18 women, 36 men) with essential hypertension (aged 39.6 +/- 9.7 years) and 25 healthy volunteers (10 women, 15 men; aged 36.0 +/- 7.2 years). A decrease in erythrocyte deformability (p < 0.01) was found in the hypertensive men compared with the hypertensive women. Hematocrit (p < 0.01), blood viscosity at the shear rates of 0.3 s-1 (p < 0.01) and 6 s-1 (p < 0.01), plasma viscosity (p < 0.01), erythrocyte aggregation (p < 0.01), and neuropeptide Y (p < 0.02) concentrations were higher in the hypertensive men than in the hypertensive women. A positive correlation between blood fibrinogen and serotonin was found in the pooled hypertensive group and in the hypertensive men (p < 0.01) and between blood viscosity (shear rate 6 s-1) and neuropeptide Y in the pooled hypertensive group (p < 0.01). Neuropeptide Y correlated with filtration time of 1 mL blood in the hypertensive men (p < 0.05) and in the pooled normotensive group (p < 0.01) and with beta-thromboglobulin in the hypertensive women (p < 0.001). A positive correlation was also found in the hypertensive men between erythrocyte and platelet aggregation (p < 0.01) and between beta-thromboglobulin and adrenaline (p < 0.01). Hemorrheological and humoral abnormalities are more pronounced in men than in women with essential hypertension and may contribute to the increased incidence of cardiovascular events in men.

Associations of ankle-brachial index with clinical coronary heart disease, stroke and preclinical carotid and popliteal atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) Study

The resting ankle-brachial index (ABI) is a non-invasive method to assess the patency of the lower extremity arterial system and to screen for the presence of peripheral occlusive arterial disease. To determine how the ABI is associated with clinical coronary heart disease (CHD), stroke, preclinical carotid plaque and far wall intimal-medial thickness (IMT) of the carotid and popliteal arteries, we conducted analyses in 15 106 middle-aged adults from the baseline examination (1987-1989) of the Atherosclerosis Risk in Communities (ARIC) Study. The prevalence of clinical CHD, stroke/transient ischemic attack (TIA) and preclinical carotid plaque increased with decreasing ABI levels, particularly at those of < 0.90. Individuals with ABI < 0.90 were twice as likely to have prevalent CHD as those with ABI > 0.90 (age-adjusted odds ratio (OR) ranging from 2.2 (95% CI: 1.0-5.1) in African-American men to 3.3 (95% CI: 2.1-5.0) in white men). Men with ABI < 0.90 were more than four times as likely to have stroke/TIA as those with ABI > 0.90 (age-adjusted OR: 4.2 (95% CI: 1.8-9.5) in African-American men and 4.9 (95% CI: 2.6-9.0) in white men). In women the association was weaker and not statistically significant. Among those free of clinical cardiovascular disease, individuals with ABI < or = 0.90 had statistically significantly higher prevalence of preclinical carotid plaque compared to those with ABI > 0.90 (age-adjusted ORs ranging from 1.5 (95% CI: 1.0-1.9) in white women to 2.6 (95% CI: 1.0-6.6) in african-american men). The ABI was also inversely associated with far wall IMT of the carotid arteries (in both men and women) and the popliteal arteries (in men only). The associations of ABI with clinical CHD, stroke, preclinical carotid plaque and IMT of the carotid and popliteal arteries were attenuated and often not statistically significant after further adjustment for LDL cholesterol, cigarette smoking, hypertension and diabetes. These data demonstrate that low ABI levels, particularly those of < 0.90, are indicative of generalized atherosclerosis.