The relative importance of vascular structure and function in predicting cardiovascular events

Insulin resistance and the metabolic syndrome are associated with arterial stiffness in patients with chronic kidney disease

BACKGROUND

Insulin resistance (IR) and the metabolic syndrome (MetS) may contribute to cardiovascular risk in chronic kidney disease (CKD). We examine the association between IR and vascular function in CKD. Furthermore, we define the prevalence of MetS and examine the association between defining MetS and vascular function.

METHODS

This cross-sectional study of 71 stage 3-4 CKD subjects assessed arterial stiffness (pulse wave velocity (PWV) and endothelial dysfunction (ED). IR was assessed using Homeostasis Model Assessment-IR (HOMA-IR). MetS was defined by the unified International Diabetes Federation and American Heart Association/National Heart Lung and Blood Institute criteria.

RESULTS

CKD subjects with HOMA-IR score above the median had significantly higher body mass index and waist circumference. They also had higher PWV, higher triglycerides with lower high-density lipoprotein concentration (P < 0.05). Age, systolic blood pressure, and HOMA-IR were independently associated with PWV, even after exclusion of diabetic subjects (n = 16) (P ≤ 0.05). MetS was more prevalent in CKD (78.9%) than controls (2.5%). MetS in CKD was associated with increased PWV (MetS(+) geometric mean = 9.5 m/s, 95% confidence interval (95% CI) = 8.9-10.2 m/s; vs. MetS(-) 8.1 m/s, 95% CI = 7.1-9.3 m/s; P = 0.03) but not ED. In a multiple logistic regression analysis, PWV higher than the median was independently associated with dysglycemia.

CONCLUSIONS

IR is independently associated with arterial stiffness, even in nondiabetic CKD. MetS is common and identified a subgroup of CKD patients with increased arterial stiffness, which is associated with dysglycemia.

Short sleep duration is associated with carotid intima-media thickness among men in the Coronary Artery Risk Development in Young Adults (CARDIA) Study

BACKGROUND AND PURPOSE

Carotid intima-media thickness (CIMT) is a subclinical marker of cardiovascular disease. Recent studies suggest that shorter sleep duration is a risk factor for cardiovascular disease, but there is limited evidence regarding this association using high-quality, objective assessments of sleep. The aim of this study is to determine whether sleep duration is associated with CIMT.

METHODS

The study used an observational cohort consisting of 617 black and white middle-aged healthy participants (37-52 years; 58% female) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Multivariable-adjusted linear regression analyses were performed. Sleep duration was measured using wrist actigraphy monitors. CIMT was calculated using the average of 20 measurements of the mean common carotid, bulb, and internal CIMT, which was assessed using ultrasound images.

RESULTS

After adjusting for covariates, 1 hour of longer sleep duration was associated with 0.026 mm less CIMT among men (P=0.02; 95% CI, -0.047 to -0.005) and 0.001 mm less CIMT among women (P=0.91; 95% CI, -0.020 to 0.022). Segment-specific analyses indicated that the carotid bulb was a key driver of the observed association.

CONCLUSIONS

Shorter objectively assessed sleep duration was associated with greater CIMT among men but not women.

TNF-α induces endothelial dysfunction via PKC-ζ-dependent NADPH oxidase activation

Endothelial dysfunction is implicated in a variety of cardiovascular diseases although the detailed mechanisms are not yet completely understood. A relationship has been suggested to exist between inflammation and endothelial dysfunction. TNF-α serves as one of the most important pro-inflammatory cytokines. The main objectives of the present study were to explore the effect of PKC-ζ on TNF-α-impaired endothelial function as well as the underlying mechanisms. Acetylcholine-induced endothelium-dependent vasodilation of mouse thoracic aorta stimulated by TNF-α was initially determined. PKC-ζ deficient mice and the specific inhibitor of NADPH oxidase were respectively applied to elucidate their roles in TNF-α-induced endothelial dysfunction. In vitro superoxide generation in HAECs was detected by DHE staining after administration of TNF-α. Meanwhile, the regulatory p47(phox) subunit of NADPH oxidase was evaluated by Western blotting and RT-PCR. The results showed that TNF-α conspicuously impaired endothelium-dependent vasodilation and the impairment was attenuated by either depleting PKC-ζ or inhibiting NADPH oxidase. In vitro TNF-α increased superoxide production and p47(phox) expression in HAECs, and such increases could be ameliorated by the specific PKC-ζ inhibitor. Our findings suggest that superoxide over-production triggered by PKC-ζ-dependent NADPH oxidase activation contributes to TNF-α-induced endothelial dysfunction.

Flow-mediated dilation and cardiovascular risk prediction: a systematic review with meta-analysis

BACKGROUND

Flow-mediated dilation (FMD) is an accepted technique to quantify endothelial function and has shown to have prognostic value for future cardiovascular disease (CVD). The predictive strength of FMD in CVD patients compared to populations not diagnosed for CVD warrants further investigation. We systematically reviewed prospective studies that investigated the association between brachial FMD and future cardiovascular events, with particular focus on the role of underlying health status.

METHODS

To obtain eligible studies, several literature databases were systematically searched through March 2011. Pooled overall risk estimates were calculated separately for continuous risk estimates for CVD (per 1% higher FMD) and for categorical risk estimates for CVD (having high vs. low FMD), based on random-effects models.

RESULTS

A total of 23 studies including 14,753 subjects were eligible for inclusion in the meta-analysis. For studies reporting continuous risk estimates, the pooled overall CVD risk was 0.92 (95%CI: 0.88; 0.95) per 1% higher FMD. The observed association seemed stronger (P-value<0.01) in diseased populations than in asymptomatic populations (0.87 (95%CI: 0.83; 0.92) and 0.96 (95%CI: 0.92; 1.00) per 1% higher FMD, respectively). For studies reporting categorical risk estimates, the pooled overall CVD risk for high vs. low FMD was similar in both types of populations, on average 0.49 (95%CI: 0.39; 0.62).

CONCLUSIONS

Our findings show that brachial FMD is inversely associated with future CVD events, with some indications for a stronger relation in diseased populations. Endothelial dysfunction may be considered relevant for classifying subjects in terms of CVD risk.

Effect of Transradial Coronary Angiography Procedure on Vascular Diameter and Vasodilator Functions in the Access Site

The present study aimed to investigate the long-term effects of transradial procedures on the radial artery diameter and vasodilator properties. The study included a total of 35 patients (28 males and 7 females) who underwent left transradial coronary angiography with an appropriate indication. The radial artery diameters were measured before and after flow-mediated vasodilation (FMD) and nitrate-mediated vasodilation (NMD). The nonintervened right radial artery served as the control. A marked narrowing in the diameter of the intervened radial artery and impaired FMD response indicating endothelial dysfunction were observed at a mean of 9 months after transradial intervention. Structural and functional changes should be taken into consideration if previously intervened radial artery would be used for interventions, such as arterial bypass graft or dialysis fistula.

Associations among different functional and structural arterial wall properties and their relations to traditional cardiovascular risk factors in healthy subjects: a cross-sectional study

BACKGROUND

The arterial wall possesses several functional and structural properties that define arterial health. Once they become impaired, cardiovascular risk increases. We aimed to ascertain the pattern of correlations among different arterial wall properties and to explore their relations to traditional risk factors and cardiovascular risk stratification. To allow such an investigation a middle-aged healthy population was recruited.

METHODS

This cross-sectional study included 100 healthy males (aged 41.9 ± 6.4 years). Pulse wave velocity (PWV), β-stiffness and intima-media thickness (IMT) of the carotid artery, and brachial artery flow-mediated dilation (FMD) were measured by a standardized ultrasound approach.

RESULTS

No correlation between FMD and IMT was found; only relatively poor correlations between PWV (or β-stiffness) and FMD existed, as well as between PWV (or β-stiffness) and IMT. PWV and β-stiffness highly correlated. Unexpectedly, only weak associations between PWV, β-stiffness, FMD, IMT and traditional risk factors were revealed. Hence, traditional risk factors (mainly age) explained only 10-50% of variability for PWV, β-stiffness, FMD and IMT. Although the subjects had low cardiovascular risk according to their Framingham score, their arterial wall properties were already impaired, particularly FMD.

CONCLUSIONS

In healthy middle-age males we found: i) absent or poor correlations among arterial stiffness, IMT and endothelial function; ii) a low impact of traditional risk factors on the studied variables, and iii) the presence of impaired arterial wall properties despite low calculated cardiovascular risk. These results provide a deepened understanding of arterial wall properties and could help to improve cardiovascular risk stratification.

Effect of cocoa/chocolate ingestion on brachial artery flow-mediated dilation and its relevance to cardiovascular health and disease in humans

Prospective studies indicate that high intake of dietary flavanols, such as those contained in cocoa/chocolate, are associated with reduced rates of cardiovascular-related morbidity and mortality in humans. Numerous mechanisms may underlie these associations such as favorable effects of flavanols on blood pressure, platelet aggregation, thrombosis, inflammation, and the vascular endothelium. The brachial artery flow-mediated dilation (FMD) technique has emerged as a robust method to quantify endothelial function in humans. Collectively, the preponderance of evidence indicates that FMD is a powerful surrogate measure for firm cardiovascular endpoints, such as cardiovascular-related mortality, in humans. Thus, literally thousands of studies have utilized this technique to document group differences in FMD, as well as to assess the effects of various interventions on FMD. In regards to the latter, numerous studies indicate that both acute and chronic ingestion of cocoa/chocolate increases FMD in humans. Increases in FMD after cocoa/chocolate ingestion appear to be dose-dependent such that greater increases in FMD are observed after ingestion of larger quantities. The mechanisms underlying these responses are likely diverse, however most data suggest an effect of increased nitric oxide bioavailability. Thus, positive vascular effects of cocoa/chocolate on the endothelium may underlie (i.e., be linked mechanistically to) reductions in cardiovascular risk in humans.

Exposure to isoflavone-containing soy products and endothelial function: a Bayesian meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

To determine whether and to what degree exposure to isoflavone-containing soy products affects EF. Endothelial dysfunction has been identified as an independent coronary heart disease risk factor and a strong predictor of long-term cardiovascular morbidity and mortality. Data on the effects of exposure to isoflavone-containing soy products on EF are conflicting.

METHODS AND RESULTS

A comprehensive literature search was conducted using the PUBMED database (National Library of Medicine, Bethesda, MD) inclusively through August 21, 2009 on RCTs using the keywords: soy, isoflavone, phytoestrogen, EF, flow mediated vasodilation, and FMD. A Bayesian meta-analysis was conducted to provide a comprehensive account of the effect of isoflavone-containing soy products on EF, as measured by FMD. A total of 17 RCTs were selected as having sufficient data for study inclusion. The overall mean absolute change in FMD (95% Bayesian CI) for isoflavone-containing soy product interventions was 1.15% (-0.52, 2.75). When the effects of separate interventions were considered, the treatment effect for isolated isoflavones was 1.98% (0.07, 3.97) compared to 0.72% (-1.39, 2.90) for isoflavone-containing soy protein. The models were not improved when considering study-specific effects such as cuff measurement location, prescribed dietary modification, and impaired baseline FMD.

CONCLUSIONS

Cumulative evidence from the RCTs included in this meta-analysis indicates that exposure to soy isoflavones can modestly, but significantly, improve EF as measured by FMD. Therefore, exposure to isoflavone supplements may beneficially influence vascular health.

Imaging atherosclerosis in HIV: carotid intima-media thickness and beyond

Chronic immune activation and inflammation are associated with an increased risk of atherosclerosis in HIV-infected patients. In this review, we discuss the role of established and novel imaging modalities to define more accurately the structure and function of inflammation-mediated atherosclerosis in the context of HIV. Historically, carotid ultrasound studies were the first to show higher rates of subclinical atherosclerosis in HIV-infected subjects versus uninfected controls. However, computed tomography is the noninvasive gold standard for imaging the coronary arteries, and studies in HIV suggest a higher prevalence of noncalcified plaque. Endothelial dysfunction can be quantified by measuring flow-mediated brachial artery dilation by ultrasound and has been used extensively in antiretroviral switching trials and small pilot trials of therapeutics to assess cardiovascular risk in this population. In the future, novel imaging modalities such as intracoronary optical coherence tomography, positron emission tomography imaging of (18)F-fluorodeoxyglucose uptake, and molecular-targeted magnetic resonance imaging will characterize the burden of vulnerable plaque and other unique features of inflammatory atherosclerosis in HIV.

Aging-shifted prostaglandin profile in endothelium as a factor in cardiovascular disorders

Age-associated endothelium dysfunction is a major risk factor for the development of cardiovascular diseases. Endothelium-synthesized prostaglandins and thromboxane are local hormones, which mediate vasodilation and vasoconstriction and critically maintain vascular homeostasis. Accumulating evidence indicates that the age-related changes in endothelial eicosanoids contribute to decline in endothelium function and are associated with pathological dysfunction. In this review we summarize currently available information on aging-shifted prostaglandin profiles in endothelium and how these shifts are associated with cardiovascular disorders, providing one molecular mechanism of age-associated endothelium dysfunction and cardiovascular diseases.

Cocoa and chocolate in human health and disease

Cocoa contains more phenolic antioxidants than most foods. Flavonoids, including catechin, epicatechin, and procyanidins predominate in antioxidant activity. The tricyclic structure of the flavonoids determines antioxidant effects that scavenge reactive oxygen species, chelate Fe2+ and Cu+, inhibit enzymes, and upregulate antioxidant defenses. The epicatechin content of cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated through anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-κB. Antioxidant effects of cocoa may directly influence insulin resistance and, in turn, reduce risk for diabetes. Further, cocoa consumption may stimulate changes in redox-sensitive signaling pathways involved in gene expression and the immune response. Cocoa can protect nerves from injury and inflammation, protect the skin from oxidative damage from UV radiation in topical preparations, and have beneficial effects on satiety, cognitive function, and mood. As cocoa is predominantly consumed as energy-dense chocolate, potential detrimental effects of overconsumption exist, including increased risk of weight gain. Overall, research to date suggests that the benefits of moderate cocoa or dark chocolate consumption likely outweigh the risks.

Cardiac and vascular structure and function parameters do not improve with alternate nightly home hemodialysis: an interventional cohort study

BACKGROUND

Nightly extended hours hemodialysis may improve left ventricular hypertrophy and function and endothelial function but presents problems of sustainability and increased cost. The effect of alternate nightly home hemodialysis (NHD) on cardiovascular structure and function is not known.

METHODS

Sixty-three patients on standard hemodialysis (SHD: 3.5-6 hours/session, 3-5 sessions weekly) converted to NHD (6-10 hours/session overnight for 3-5 sessions weekly). 2Dimensional transthoracic echocardiography and ultrasound measures of brachial artery reactivity (BAR), carotid intima-media thickness (CIMT), total arterial compliance (TAC) and augmentation index (AIX) were performed post dialysis at baseline and 18-24 months following conversion to NHD. In 37 patients, indices of oxidative stress: plasma malonyldialdehyde (MDA) and anti-oxidant enzymes: catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD) activity and total antioxidant status (TAS) were measured at baseline, 3 and 6 months.

RESULTS

Left ventricular mass index (LVMI) remained stable. Despite significant derangement at baseline, there were no changes in diastolic function measures, CIMT, BAR and TAC. AIX increased. Conversion to NHD improved bone mineral metabolism parameters and blood pressure control. Interdialytic weight gains increased. No definite improvements in measures of oxidative stress were demonstrated.

CONCLUSIONS

Despite improvement in uremic toxin levels and some cardiovascular risk factors, conversion to an alternate nightly NHD regimen did not improve cardiovascular structure and function. Continuing suboptimal control of uremic toxins and interdialytic weight gains may be a possible explanation. This study adds to the increasing uncertainty about the nature of improvement in cardiovascular parameters with conversion to intensive hemodialysis regimens. Future randomized controlled trials will be important to determine whether increases in dialysis session duration, frequency or both are most beneficial for improving cardiovascular disease whilst minimizing costs and the impact of dialysis on quality of life.

Association of a fat-derived plasma protein omentin with carotid artery intima-media thickness in apparently healthy men

Obesity is causally linked with the development of atherosclerosis. Omentin is an adipocytokine whose concentrations are reduced in obese individuals. Here we examined the relationship between plasma omentin levels and carotid intima-media thickness (IMT), a marker of early atherosclerosis, in apparently healthy Japanese men. Participants were 100 Japanese men who underwent a medical checkup. Maximal IMT (max-IMT) and mean-IMT in common carotid artery were measured by high-resolution carotid ultrasound system. Plasma omentin concentrations were determined by enzyme-linked immunosorbent assay. Circulating omentin levels correlated negatively with body mass index, waist circumference, fasting glucose, creatinine, max-IMT and mean-IMT, and positively with estimated glomerular filtration rates (eGFR). Single regression analysis demonstrated that max-IMT associated with age, eGFR and omentin levels, and that mean-IMT associated with age, fasting glucose, eGFR and omentin levels. Multiple regression analysis revealed that omentin levels, together with age, correlated with max-IMT and mean-IMT. Our data document that circulating omentin levels independently and negatively associate with carotid IMT in this population, suggesting that measurement of omentin may be useful for assessment of carotid IMT.

Multimodality vascular imaging in CKD: divergence of risk between measured parameters

BACKGROUND

High cardiovascular risk in chronic kidney disease (CKD) patients appears only partly attributable to atherosclerosis, with much of the remaining risk being ascribed to other vasculature abnormalities, including endothelial dysfunction, arterial stiffness and vascular calcification (VC). To date, these factors have been primarily studied in isolation or in dialysis patients. This study performed a global vascular assessment in moderate CKD and assessed the relationships with both traditional and novel risk factors.

METHODS

This was a prospective cross-sectional analysis of 120 patients (age 60 ± 10 years; estimated glomerular filtration rate 25-60 mL/min/1.73m(2)). Demographic, clinical and biochemical characterization was performed. VC was characterized by lateral lumbar radiograph; arterial stiffness by aortic pulse-wave velocity (PWV); atheroma burden by carotid intima-media thickness (cIMT) and endothelial function by flow-mediated dilation (FMD) of the brachial artery.

RESULTS

VC was highly prevalent (74%), and FMD generally poor (FMDΔ 3.3 ± 3.3%). There were significant correlations between all vascular parameters; although these were predominantly explained by age. cIMT was independently associated with classical risks and also PWV (adjusted standardized β = 0.31, P = 0.001). However, traditional risks showed almost no independent associations with other vascular measurements. In contrast, serum phosphate and 1,25-dihydroxyvitamin D (1,25-OHD) correlated with PWV and the presence of VC, respectively. After adjustment, every 1 pg/mL increase in 1,25-OHD was related to a 3% reduction in the chance of VC (odds ratio 0.97; 95% confidence interval 0.94-1.00, P = 0.03). Medication use, HOMA-IR and C-reactive protein did not correlate with any of the vascular measures.

CONCLUSIONS

This study demonstrates extensive vascular disease across multimodality imaging in moderate CKD. Atherosclerotic burden correlated with traditional risks and PWV, while higher 1,25-OHD was associated with less VC. The lack of association between renal function and imaging indices raises the possibility of a threshold, rather than graded uraemic effect on vascular health that warrants further exploration.

The assessment of vascular function during dietary intervention trials in human subjects

The potential to reduce cardiovascular morbidity through dietary modification remains an area of intense clinical and scientific interest. Any putatively beneficial intervention should be tested within a randomised controlled trial which records appropriate endpoints, ideally incident CVD and death. However, the large sample sizes required for these endpoints and associated high costs mean that the majority of dietary intervention research is conducted over short periods among either healthy volunteers or those at only slightly increased risk, with investigators using a diverse range of surrogate measures to estimate arterial health in these studies. The present review identifies commonly employed techniques, discusses the relative merits of each and highlights emerging approaches.

Endothelial function in resistance and conduit arteries and 5-year risk of cardiovascular disease

BACKGROUND

Impaired endothelial function has been implicated as a cause of cardiovascular disease. Little is known of the relations of measures of endothelial function in resistance and conduit arteries to incident cardiovascular disease in the general population, and available techniques have not been compared.

METHODS AND RESULTS

In 1016 participants (70 years of age) of the population-based Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study (52% women), we measured endothelium-dependent vasodilation using the invasive forearm technique with acetylcholine given in the brachial artery, the brachial artery ultrasound technique with measurement of flow-mediated dilatation, and the pulse-wave analysis-based method with β-2-agonist terbutaline provocation. During 5 years of follow-up, 101 participants experienced a composite end point of myocardial infarction, stroke, or death, excluding the 85 persons with a history of myocardial infarction or stroke at baseline. In logistic regression models adjusted for several established and novel cardiovascular disease risk factors and medications, endothelium-dependent vasodilation by the invasive forearm technique with acetylcholine was associated with risk of the end point (odds ratio, 0.72 per SD; 95% confidence interval, 0.56 to 0.93; P=0.01). Endothelial function by the other 2 methods was not related to risk of the end point. Addition of endothelium-dependent vasodilation to the Framingham risk score improved discrimination of risk of the end point.

CONCLUSIONS

Endothelium-dependent vasodilation in resistance arteries, but not in the brachial conduit artery (flow-mediated dilatation), was associated with 5-year risk of a composite end point of death, myocardial infarction, or stroke independently of major cardiovascular disease risk factors. This vascular measurement improved risk discrimination when added to an established risk score in an elderly population.

Comparison of peripheral endothelial function in shift versus nonshift workers

Shift working is related to increased cardiovascular morbidity. Peripheral endothelial dysfunction, an inherent feature of early atherosclerosis, has been suggested as a surrogate marker of cardiovascular risk. Whether shift working is associated with peripheral endothelial dysfunction has not been investigated to date. A total of 48 male shift workers (SWs) and 47 male nonshift workers (NSWs) (mean age 43 ± 5 years) were recruited from a glass manufactory. The SWs and NSWs were matched according to age, body mass index, smoking habits, family history of premature coronary artery disease, prevalence of hypercholesterolemia and hypertension, and work place. Their sport habits were also documented. Peripheral endothelial function was assessed using the EndoPAT technique to determine the peripheral arterial tone (PAT) index. According to the study design, no difference was found in the risk factor profiles between the SWs and NSWs. Despite a greater percentage of regular physical activity among the SWs (16.7 vs 4.3%, p = 0.05), shift working was associated with a reduced PAT index compared to working only on the day shift (PAT index 1.73 ± 0.4 vs 1.94 ± 0.5, p = 0.03). In the NSW group, the participants with regular physical training (n = 16) had a greater PAT index than those without regular physical activity (n = 12; PAT index 2.28 ± 0.45 vs 1.86 ± 0.51, p = 0.03). No such difference was found in the SWs. In conclusion, SWs had a reduced PAT index compared with NSWs, suggesting endothelial dysfunction. Therefore, the known increased cardiovascular risk in those shift working might be related to endothelial dysfunction.

Tea consumption enhances endothelial-dependent vasodilation; a meta-analysis

Background

Tea consumption is associated with a lower risk of cardiovascular disease including stroke. Direct effects of tea components on the vasculature, particularly the endothelium, may partly explain this association.

Objective

We performed a meta-analysis of controlled human intervention studies on the effect of tea on flow-mediated dilation (FMD) of the brachial artery, a measurement of endothelial function, which is suggested to be associated with cardiovascular risk.

Methods

Human intervention studies were identified by systematic search of the databases Medline, Embase, Chemical Abstracts and Biosis through March 2009 and by hand-searching related articles. Studies were selected based on predefined criteria: intervention with tea as the sole experimental variable, placebo-controlled design, and no missing data on FMD outcome or its variability. A random effects model was used to calculate the pooled overall effect on FMD due to the intake of tea. The impact of various subject and treatment characteristics was investigated in the presence of heterogeneity.

Results

In total, 9 studies from different research groups were included with 15 relevant study arms. The overall absolute increase in FMD of tea vs. placebo was 2.6% of the arterial diameter (95% CI: 1.8-3.3%; P-value <0.001) for a median daily dose of 500 mL of tea (2–3 cups). This is a relative increase of approximately 40% compared to the average FMD of 6.3% measured under placebo or baseline conditions. There was significant heterogeneity between studies (P-value <0.001) that might partly be explained by the cuff position either distal or proximal to the area of FMD measurement. No indication for publication bias was found.

Conclusion

Moderate consumption of tea substantially enhances endothelial-dependent vasodilation. This may provide a mechanistic explanation for the reduced risk of cardiovascular events and stroke observed among tea drinkers.

Flow-mediated dilation and cardiovascular event prediction: does nitric oxide matter?

Endothelial dysfunction is an early atherosclerotic event that precedes clinical symptoms and may also render established plaque vulnerable to rupture. Noninvasive assessment of endothelial function is commonly undertaken using the flow-mediated dilation (FMD) technique. Some studies indicate that FMD possesses independent prognostic value to predict future cardiovascular events that may exceed that associated with traditional risk factor assessment. It has been assumed that this association is related to the proposal that FMD provides an index of endothelium-derived nitric oxide (NO) function. Interestingly, placement of the occlusion cuff during the FMD procedure alters the shear stress stimulus and NO dependency of the resulting dilation: cuff placement distal to the imaged artery leads to a largely NO-mediated response, whereas proximal cuff placement leads to dilation which is less NO dependent. We used this physiological observation and the knowledge that prognostic studies have used both approaches to examine whether the prognostic capacity of FMD is related to its role as a putative index of NO function. In a meta-analysis of 14 studies (>8300 subjects), we found that FMD derived using a proximal cuff was at least as predictive as that derived using distal cuff placement, despite the latter being more NO dependent. This suggests that, whilst FMD is strongly predictive of future cardiovascular events, this may not solely be related to its assumed NO dependency. Although this finding should be confirmed with more and larger studies, we suggest that any direct measure of vascular (endothelial) function may provide independent prognostic information in humans.

Different effects of isoflavones on vascular function in premenopausal and postmenopausal smokers and nonsmokers: NYMPH study

Isoflavone intake has been associated with a reduction in the risk of cardiovascular disease in postmenopausal women. The aim of the present study was to determine if the effects of isoflavones on vascular function differ between premenopausal and postmenopausal women and between women who smoke and those who do not. Women smokers and nonsmokers who consumed 50 mg of isoflavone/day as black soybean tea for a period of 2 months (n = 55, mean age 39) were enrolled in the present study. We examined endothelial function, which was assessed by the percent change in flow-mediated dilation (%FMD) and arterial wall stiffness using the cardio-ankle vascular index (CAVI), as well as by biochemical parameters of the blood. Neither premenopausal (p = 0.697) nor postmenopausal (p = 0.389) smokers experienced an increase in %FMD after daily consumption of isoflavones. However, both premenopausal (p = 0.004) and postmenopausal (p = 0.019) nonsmokers exhibited a marked elevation in %FMD. By contrast, isoflavone intake effectively reduced CAVI among both premenopausal smokers (p = 0.027) and nonsmokers (p = 0.013), but had no effect on CAVI among postmenopausal smokers (p = 0.169) or nonsmokers (p = 0.128). The women smokers and nonsmokers did not differ in age or %FMD at the time of enrollment in the study. Thus, isoflavones have different effects on vascular endothelial function and arterial wall stiffness in premenopausal and postmenopausal smokers and nonsmokers.

Assessment of flow-mediated dilation in humans: a methodological and physiological guideline

Endothelial dysfunction is now considered an important early event in the development of atherosclerosis, which precedes gross morphological signs and clinical symptoms. The assessment of flow-mediated dilation (FMD) was introduced almost 20 years ago as a noninvasive approach to examine vasodilator function in vivo. FMD is widely believed to reflect endothelium-dependent and largely nitric oxide-mediated arterial function and has been used as a surrogate marker of vascular health. This noninvasive technique has been used to compare groups of subjects and to evaluate the impact of interventions within individuals. Despite its widespread adoption, there is considerable variability between studies with respect to the protocols applied, methods of analysis, and interpretation of results. Moreover, differences in methodological approaches have important impacts on the response magnitude, can result in spurious data interpretation, and limit the comparability of outcomes between studies. This review results from a collegial discussion between physiologists with the purpose of developing considered guidelines. The contributors represent several distinct research groups that have independently worked to advance the evidence base for improvement of the technical approaches to FMD measurement and analysis. The outcome is a series of recommendations on the basis of review and critical appraisal of recent physiological studies, pertaining to the most appropriate methods to assess FMD in humans.

Measuring FMD in the brachial artery: how important is QRS gating?

Recommendations for the measurement of brachial flow-mediated dilation (FMD) typically suggest images be obtained at identical times in the cardiac cycle, usually end diastole (QRS complex onset). This recommendation presumes that inter-individual differences in arterial compliance are minimized. However, published evidence is conflicting. Furthermore, ECG gating is not available on many ultrasound systems; it requires an expensive software upgrade or increased image processing time. We tested whether analysis of images acquired with QRS gating or with the more simplified method of image averaging would yield similar results. We analyzed FMD and nitroglycerin-mediated dilation (NMD) in 29 adults with type 2 diabetes mellitus and in 31 older adults and 12 young adults without diabetes, yielding a range of brachial artery distensibility. FMD and NMD were measured using recommended QRS-gated brachial artery diameter measurements and, alternatively, the average brachial diameters over the entire R-R interval. We found strong agreement between both methods for FMD and NMD (intraclass correlation coefficients = 0.88-0.99). Measuring FMD and NMD using average diameter measurements significantly reduced post-image-processing time (658.9 ± 71.6 vs. 1,024.1 ± 167.6 s for QRS-gated analysis, P < 0.001). FMD and NMD measurements based on average diameter measurements can be performed without reducing accuracy. This finding may allow for simplification of FMD measurement and aid in the development of FMD as a potentially useful clinical tool.

Assessment of atherosclerosis: the role of flow-mediated dilatation

Evidence suggests that endothelial dysfunction is on the causal pathway for both atherogenesis and destabilization of established plaques. In this review, the role of flow-mediated dilatation (FMD) as a non-invasive method to assess endothelial function is discussed. Technical modifications and development of analysis software have significantly improved the variability of the method. Following a strict standardized protocol enables reproducible measurements to be achieved and export of the technique from specialized laboratories to population studies and multicentre settings. Endothelial function assessed by FMD has been shown to be affected by cardiovascular risk factors, to be related to structural arterial disease and to cardiovascular outcome, validating its use for studying the pathophysiology of arterial disease. Numerous studies have also demonstrated that it is responsive to physiological and pharmacological interventions. Flow-mediated dilatation provides unique opportunities in drug development programmes to assess an early rapidly responsive signal of risk or benefit, complementing endpoints of structural arterial disease and cardiovascular outcomes that take much longer and are more expensive.

Changes in blood dendritic cell counts in relation to type of coronary artery disease and brachial endothelial cell function

BACKGROUND

Recently we reported a decline of circulating myeloid (m) and plasmacytoid (p) dendritic cells (DCs) in patients with coronary artery disease (CAD). This study also determined the total blood DC numbers and focused on effects of extent (one vs. three-vessel disease) and type (stable vs. unstable) of CAD, and on endothelial cell function.

METHODS

Patients undergoing diagnostic coronarography were enrolled in four groups: control patients (atypical chest pain, <50% narrowing, n=15), stable one-vessel (n=15), stable three-vessel (n=15), and unstable one-vessel CAD (n=16). Total blood DCs were identified as lineage (lin) and HLADR, and DC subtypes with blood DC antigen (BDCA)-1 for mDCs and BDCA-2 for pDCs. Flow-mediated dilatation (FMD) was measured in the brachial artery.

RESULTS

Numbers of total blood DCs, mDCs and pDCs declined in CAD patients compared with control patients, but without differences between the CAD groups. Interleukin-6 and high sensitivity C-reactive protein displayed inverse associations with mDCs. A FMD below the median of the study population, use of beta-blockers or of lipid-lowering drugs was associated with increased mDCs, whereas pDCs were similar. Interestingly, the effects of drugs and FMD were additive with that of CAD.

CONCLUSION

This study indicates that lower blood DCs do not result from medication intake or endothelial dysfunction, and are an overall systemic effect of atherosclerosis rather than CAD type (stable or unstable) or number of stenotic coronary arteries. In view of discrete associations with cytokines, FMD, beta-blockers and statins, mDCs and pDCs seem to behave differently and may influence inflammation during atherosclerosis in different ways.

Prediction of future cardiovascular outcomes by flow-mediated vasodilatation of brachial artery: a meta-analysis

BACKGROUND

We conducted a meta-analysis of observational studies which examined the association between flow-mediated dilatation (FMD) of brachial artery, a noninvasive measure of endothelial function, and future cardiovascular events.

METHODS

Electronic databases were searched using a predefined search strategy. Data was independently abstracted on study characteristics, study quality, and outcomes by two reviewers. The multivariate relative risks, adjusted for confounding factors, were calculated from individual studies and then pooled using random-effects models. Statistical heterogeneity was evaluated using I2 statistics. Subgroup analyses and meta-regression analyses were conducted to assess the robustness of the meta-analysis. Publication bias was examined with funnel plot analysis and Egger's test.

RESULTS

Four population-based cohort studies and ten convenience-cohort studies, involving 5,547 participants, were included in the meta-analysis. The pooled relative risks of cardiovascular events per 1% increase in brachial FMD, adjusted for confounding risk factors, was 0.87 (95% CI, 0.83- 0.91). The significant associations between brachial FMD and cardiovascular events were consistent among all subgroups evaluated, suggesting the robustness of the meta-analysis. However, the presence of heterogeneity in study quality, the remaining confounding factors, and publication bias in the available literature prevent a definitive evaluation of the additional predictive value of brachial FMD beyond traditional cardiovascular risk factors.

CONCLUSIONS

The meta-analysis of heterogeneous studies with moderate methodological quality suggested that impairment of brachial FMD is significantly associated with future cardiovascular events. Further prospective randomized trials are warranted to confirm the efficacy of the usage of brachial FMD in the management of cardiovascular diseases.

Microvascular angina. The possible role of inflammation, uric acid, and endothelial dysfunction

Microvascular angina is a condition characterized by angina-like chest pain and normal coronary angiography. Endothelial dysfunction and systemic inflammation with elevated serum high-sensitive C-reactive protein (hsCRP) levels play a role in its pathogenesis. This study aimed to explore the possible relation between CRP, brachial flow-mediated dilatation (FMD), and microvascular angina.We included 21 patients with attacks of chest pain diagnosed as microvascular angina (study group) and 10 normal asymptomatic subjects (control group). Patients and controls were thoroughly examined clinically and by echocardiography, electrocardiography, and brachial FMD (using external brachial ultrasonography). Serum hsCRP and uric acid levels were assessed in all subjects.A significantly higher mean hsCRP level was found in the study group compared to controls (11.5+/-3.8 versus 3.34+/-1.5 mg/L; P<0.001). FMD of the brachial artery showed significant impairment in patients with microvascular angina compared to controls (0.16+/-0.06 versus 0.76+/-0.09 mm; P<0.001). There were significantly higher total cholesterol (196.1+/-44.4 versus 159.8+/-14.5 mg/dL; P=0.018) and triglyceride levels (185.0+/-103.2 versus 113.0+/-17.6 mg/dL; P=0.038) in the patients compared to controls; but there was a statistically insignificant difference in mean serum uric acid levels between these two groups. There were no significant correlations between the brachial FMD and any of the clinical variables studied (apart from ankle/brachial index). Microvascular angina may have an inflammatory element (reflected as a higher serum hsCRP level), together with a contribution by endothelial dysfunction (reflected as impaired brachial artery FMD); while serum uric acid is possibly not associated with microvascular angina.

Baseline values but not treatment-induced changes in carotid intima-media thickness predict incident cardiovascular events in treated hypertensive patients: findings in the European Lacidipine Study on Atherosclerosis (ELSA)

BACKGROUND

Baseline carotid intima-media thickness (IMT) and plaques are considered predictors of cardiovascular events, but whether they maintain predictive value in treated hypertensive patients and whether time-related (or treatment-induced) IMT changes are additional predictors are unknown.

METHODS AND RESULTS

Analyses were performed of the data from the European Lacidipine Study on Atherosclerosis (ELSA), a large, randomized, intervention trial in which 2334 hypertensive patients from 7 European countries were followed up under effective antihypertensive treatment for 3.75 years. Kaplan-Meier curves indicated progressively lower survival free of any type of outcome except stroke, with increasing baseline IMT quartiles or increasing IMT values, even after adjustment for major baseline risk factors. Incidence of any outcome except stroke also was related to baseline number of carotid plaques. However, when both baseline and on-treatment IMT values were entered in Cox proportional-hazards models, differences in IMT compared with baseline did not predict cardiovascular outcomes. Although on-treatment rather than baseline IMT values significantly entered some of the proportional-hazards models, baseline and on-treatment IMTs were highly correlated, and therefore these results are inconclusive.

CONCLUSIONS

ELSA shows that carotid intima-media thickening and plaques are important added risks of cardiovascular outcomes in a treated hypertensive population independently of blood pressure and traditional risk factors. However, the analysis failed to show a predictive role of treatment-dependent IMT changes. These negative conclusions should be tempered by the limitations inherent in the smallness of these changes compared with the large individual differences in baseline IMTs.

Flow-mediated dilatation has no independent prognostic effect in patients with chest pain with or without ischaemic heart disease

OBJECTIVE

The purpose of this study was to assess the prognostic effect of flow-mediated dilatation (FMD) in patients with chest pain admitted to a coronary care unit.

METHODS

Endothelium-dependent FMD in the brachial artery was examined in 223 patients with acute chest pain. All patients underwent a stress test at the time of admittance. On the basis of a positive stress test, a prior myocardial infarction (MI), prior percutaneous coronary intervention (PCI) or coronary bypass surgery (CABG), 137 patients were categorized as having ischaemic heart disease (IHD).

RESULTS

Patients with IHD had significantly lower FMD than patients without IHD (p=0.002). During a mean follow-up of 4.2 years, 90 patients had an endpoint event, i.e. cardiovascular death, acute MI, unstable angina pectoris, PCI or CABG. In univariate analysis, FMD <3 % was associated with an increased hazard of the combined endpoint (p=0.04). In multivariate analysis, adjusted for age, gender, IHD and body mass index, no association between FMD and the combined endpoint was found (p=0.99).

CONCLUSION

FMD is associated with IHD, but has no independent prognostic effect in patients with chest pain.

Influence of visceral obesity and liver fat on vascular structure and function in obese subjects

Endothelial dysfunction and increased intima-media thickness (IMT) have been found in obese patients. Both regional fat distribution and liver steatosis may influence these markers of subclinical atherosclerosis. We sought to determine the interrelationships of endothelial function, carotid IMT, visceral and subcutaneous adipose tissue accumulation, and liver steatosis in severely obese subjects. In 64 severely obese patients (BMI 42.3 +/- 4.3 kg/m(2)), we determined (i) endothelial function as flow-mediated dilation (FMD) of the brachial artery, (ii) carotid IMT, (iii) visceral fat diameter, and (iv) degree of liver steatosis using ultrasound. FMD was associated inversely with visceral fat diameter and degree of steatosis (r = -0.577, P < 0.0001 and r = -0.523, P < 0.0001, respectively). Carotid IMT correlated with visceral fat mass (r = 0.343, P = 0.007) but not with liver steatosis. After adjustment for conventional cardiovascular risk factors, FMD was predicted independently by the visceral fat diameter, age, and sex (r(2) = 0.48, P < 0.0001), but not by the degree of liver steatosis or plasma adiponectin levels. In contrast, age and sex were the only predictors of IMT (r(2) = 0.33, P < 0.001). In obese patients, visceral fat diameter is a major determinant of endothelial dysfunction, independent of traditional risk factors or the degree of liver steatosis and plasma adiponectin. Measurement of visceral fat diameter by ultrasound is a novel and simple method to identify subjects with an increased risk for atherosclerosis within an obese population.

Predictive value of brachial flow-mediated dilation for incident cardiovascular events in a population-based study: the multi-ethnic study of atherosclerosis

BACKGROUND

Although brachial artery flow-mediated dilation (FMD) predicts recurrent cardiovascular events, its predictive value for incident cardiovascular disease (CVD) events in adults free of CVD is not well established. We assessed the predictive value of FMD for incident CVD events in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS AND RESULTS

Brachial artery FMD was measured in a nested case-cohort sample of 3026 of 6814 subjects (mean+/-SD age, 61.2+/-9.9 years) in MESA, a population-based cohort study of adults free of clinical CVD at baseline recruited at 6 clinic sites in the United States. The sample included 50.2% female, 34.3% white, 19.7% Chinese, 20.8% black, and 25.1% Hispanic subjects. Probability-weighted Cox proportional hazards analysis was used to examine the association between FMD and 5 years of adjudicated incident CVD events, including incident myocardial infarction, definite angina, coronary revascularization (coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, or other revascularization), stroke, resuscitated cardiac arrest, and CVD death. Mean (SD) FMD of the cohort was 4.4% (2.8). In probability-weighted Cox models, FMD/unit SD was significantly associated with incident cardiovascular events in the univariate model (adjusted for age and sex) (hazard ratio, 0.79; 95% confidence interval, 0.65 to 0.97; P=0.01), after adjustment for the Framingham Risk Score (FRS) (hazard ratio, 0.80; 95% confidence interval, 0.62 to 0.97; P=0.025), and in the multivariable model (hazard ratio, 0.84; 95% confidence interval, 0.71 to 0.99; P=0.04) after adjustment for age, sex, diabetes mellitus, cigarette smoking status, systolic blood pressure, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, heart rate, statin use, and blood pressure medication use. The c statistic (area under the curve) values of FMD, FRS, and FRS+FMD were 0.65, 0.74, and 0.74, respectively. Compared with the FRS alone, the addition of FMD to the FRS net correctly reclassifies 52% of subjects with no incident CVD event but net incorrectly reclassifies 23% of subjects with an incident CVD event, an overall net correct reclassification of 29% (P<0.001).

CONCLUSIONS

Brachial FMD is a predictor of incident cardiovascular events in population-based adults. Even though the addition of FMD to the FRS did not improve discrimination of subjects at risk of CVD events in receiver operating characteristic analysis, it improved the classification of subjects as low, intermediate, and high CVD risk compared with the FRS.

Brachial artery diameter is related to cardiovascular risk factors and intima-media thickness

BACKGROUND

Previous reports showed inconsistent results about the potential role of flow-mediated dilatation (FMD) in cardiovascular(CV) risk prediction. Few data are available about the role of nitroglycerin-mediated dilatation (NMD), but recently, brachial artery diameter(BAD) appeared to have predictive value in CV risk prediction.We determined the relation of FMD, BAD and NMD with known CV risk factors and intima-media thickness (IMT), a well-established surrogate marker of atherosclerosis, in a community-based population, the Nijmegen Biomedical Study (NBS).

MATERIALS AND METHODS

FMD, BAD and NMD were measured in the brachial, and IMT in the common carotid artery ultrasononically in 337 participants, aged 50-70 years. Traditional clinical and biochemical parameters were determined.

RESULTS

Both FMD and NMD were not correlated with most CV risk factors or prevalent CVD. However, both IMT and BAD did show significant correlations with CV risk factors. In accordance, both IMT and BAD were significantly correlated with prevalent CVD (r=0.62 and r=-0.37, respectively) . Furthermore, FMD was not correlated with IMT and did hardly (R2=1.1%) improve the prediction of IMT by CV risk factors in regression analysis. However, both BAD and NMD did correlate with IMT (r=-0.29 and r=0.25, respectively).

CONCLUSION

In our study, FMD and NMD were not related to known CV risk factors and prevalent CVD, and FMD was not correlated with IMT, a surrogate marker of atherosclerosis. Most intriguingly, BAD was significantly correlated with some CV risk factors, prevalent CVD and IMT. So, BAD is a potential valuable tool in CV risk prediction in middle-aged low-risk populations, whereas FMD is not.

Plasma tetrahydrobiopterin/dihydrobiopterin ratio: a possible marker of endothelial dysfunction

BACKGROUND

Although endothelium-dependent vasodilatation has been used as a marker of endothelial dysfunction (ED), there have been no reliable plasma markers for ED. Oxidative stress, which is a major determinant of ED, oxidizes tetrahydrobiopterin (BH4), an essential cofactor of endothelial type nitric oxide synthase (eNOS), and resulted in the relative deficiency of BH4.

METHODS AND RESULTS

In 163 patients with cardiovascular disorders, the plasma levels of BH4 and 7, 8-dihydrobiopterin (BH2) by high performance liquid chromatography were measured and compared with the flow-mediated (FMD) vasodilatory response of the brachial artery, which was measured by ultrasonography. The effects of atorvastatin on plasma pteridine levels and FMD were examined in patients with multiple coronary risk factors. There was a positive relationship between FMD and plasma BH4 levels and a negative relationship between FMD and plasma BH2 levels. Subsequently, a strong positive relationship between FMD and the BH4/BH2 ratio (r=0.585, P<0.0001) was found. Although we did not find any significant relationship between pteridine levels and individual traditional risk factors, the BH4/BH2 ratio in patients with more than 2 risk factors showed significant reductions compared with that in those without risk factors. Statin treatment improved FMD in association with an increase in the plasma BH4/BH2 ratio.

CONCLUSIONS

Plasma pteridine levels were associated with endothelial dysfunction in cardiovascular disorders.

The impact of nitric oxide in cardiovascular medicine: untapped potential utility

The structural integrity and functional activity of the endothelium play an important role in atherogenesis and related adverse outcomes. Cardiovascular disease risk conditions contribute to oxidative stress, which causes a disruption in the balance between nitric oxide (NO) and reactive oxygen species, with a resulting relative decrease in bioavailable NO and/or the NO-soluble guanylate cyclase cascade in blood vessels. This leads to endothelial and vascular smooth muscle cell dysfunction, resulting in increased tone and alterations in cell growth and gene expression that create a prothrombotic, proinflammatory environment. This leads to formation, progression, and destabilization of atherosclerotic plaques which may result in myocardial infarction, stroke, and cardiovascular death. NO clearly has a critical role in the maintenance and repair of the vasculature, and a decrease in bioavailable NO is linked to adverse outcomes. This background provides the rationale for exploring the potential therapeutic role for NO-donating agents in the prevention of adverse cardiovascular outcomes.

Obstructive sleep apnea and atherosclerosis

Obstructive sleep apnea (OSA) is associated with significant cardiovascular morbidity and excess in mortality. Atherosclerosis has been shown to occur in OSA patients free of any other significant risk factors. In particular, intima media thickness, an early marker of atherosclerosis, may be increased at the carotid level in OSA. Thus, early atherosclerosis could be one of the intermediary mechanisms supporting the link between OSA and cardiovascular morbidity. The current concept is that the development of atherosclerotic lesions results from a dynamic interplay between the native cells of the vasculature and different proinflammatory leukocytes issued from the general circulation. Immunoinflammatory cells dominate early atherosclerotic processes, with the secretion of several proinflammatory molecules aggravating lesion progression. There is now substantial evidence that intermittent hypoxia in rodents, as a partial model of sleep apnea, triggers atherogenesis. Blood pressure alterations and hemodynamic strains on the vascular wall, impairment in vascular reactivity, lipid metabolism dysregulation, and activation of proinflammatory transcription factors at the vascular wall level are among the key factors promoting atherosclerosis. Specifically, increases in leukocyte rolling and adhesion molecule expression at the endothelial cell level have been shown to occur in the first 2 weeks after intermittent hypoxia exposure initiation. Early changes at the vascular wall level have been shown in OSA patients and its reversibility under continuous positive airway pressure has also been suggested. Several biological markers potentially linked with early atherosclerosis development are under study in OSA patients. Further studies are needed to identify at-risk subjects prone to develop vascular changes because OSA treatment may either be initiated earlier or combined with specific drug treatments.

Gender differences on brachial flow-mediated dilation and carotid intima-media thickness for prediction of spontaneous cardiovascular events

BACKGROUND

Impaired brachial flow-mediated dilation (FMD) and increased carotid intima-media thickness (IMT) are associated with increased risk of cardiovascular events.

METHODS

We measured brachial FMD and a mean of 12 sites maximum carotid IMT (mmIMT) in 279 patients (mean age 62 +/- 12 y; 163 men) admitted for coronary angiography due to chest pain.

HYPOTHESIS

There are gender differences in the predictive values of FMD and IMT for cardiovascular events.

RESULTS

Univariable analysis showed that impaired FMD (p < 0.001), but not increased mmIMT (p = 0.056), significantly predicted spontaneous cardiovascular events. After adjusting for the extent of coronary artery disease (CAD) and other clinical variables, age (heart rate [HR] 1.05, 95% confidence interval [CI]: 1.01-1.09, p = 0.017) and FMD (HR 0.85, 95% CI: 0.75-0.97, p = 0.012) were independent predictors for cardiovascular events. A total of 148 (53%) patients had CAD (> or =50% diameter stenosis). Over a median follow-up of 16 mo, 36 (12.9%) patients experienced spontaneous cardiovascular events (cardiovascular death, stroke, acute myocardial infarction [MI], unstable angina pectoris, and congestive heart failure [HF]). Women were more likely than men to develop cardiovascular events in patients without significant CAD (11.9% versus 1.6%, odds ratio [OR] = 8.54, p = 0.033), but not in those patients with CAD (20.4 % versus 17.2%, OR = 1.24, p = 0.66). Moreover, women accounted for 8 (88.9%) events in non-CAD patients. Furthermore, impaired FMD predicted the occurrence of cardiovascular events in both men and women (p < 0.05).

CONCLUSION

Brachial FMD, rather than carotid IMT, was an independent predictor for cardiovascular events after adjusting for the extent of CAD. Moreover, impaired brachial endothelial function in women without significant CAD was associated with an increased risk of spontaneous cardiovascular events.

Measurement of arterial stiffness in subjects with vascular disease: Are vessel wall changes more sensitive than increase in intima-media thickness?

BACKGROUND AND AIMS

It is widely accepted that subjects with vascular disease have increased arterial stiffness and intima-media thickness (IMT) when compared with healthy controls. The aim of this study was to investigate indices of arterial stiffness and IMT in the common carotid arteries (CCAs) of subjects with and without peripheral arterial disease (PAD), in order to look for evidence of change in wall quality and quantity to explain increased stiffness that has been found in the arteries of subjects with vascular disease.

METHODS AND RESULTS

The arterial distension waveform (ADW), IMT, diameter and brachial blood pressure were measured to calculate Young's Modulus (E) and elastic modulus (Ep) in the common carotid arteries of subjects with and without PAD. 38 subjects with confirmed PAD were compared with 43 normal controls matched for age, sex, smoking and hypertension. The mean diameter (8.35mm [95% CI 7.93-8.77] vs. 6.93mm [6.65-7.20] P<0.001, increase 20%), IMT (0.99mm [0.92-1.07] vs. 0.88mm [0.82-0.93] P=0.020, increase 12.5%), Ep (315kPa [185-444] vs. 190kPa [164-216] P=0.034, increase 66%) and E (1383kPa [836-1930] vs. 744kPa [641-846] P=0.006, increase 86%) were all significantly higher in subjects with PAD.

CONCLUSIONS

This study suggests that increased stiffness observed in subjects with peripheral vascular disease is a result of change in both quantity and quality of the arterial wall. Changes in indices of arterial stiffness were much higher than changes in IMT and diameter. These preliminary observations may be an indication that indices of arterial stiffness are a sensitive early marker of atherosclerosis.

Endothelial dysfunction, carotid artery plaque burden, and conventional exercise-induced myocardial ischemia as predictors of coronary artery disease prognosis

Background

While both flow-mediated vasodilation (FMD) in the brachial artery (BA), which measures endothelium-dependent vasodilatation, and intima-media thickness (IMT) in the carotid artery are correlated with the prognosis of coronary artery disease (CAD), it is not clear which modality is a better predictor of CAD. Furthermore, it has not been fully determined whether either of these modalities is superior to conventional ST-segment depression on exercise stress electrocardiogram (ECG) as a predictor. Thus, the goal of the present study was to compare the predictive value of FMD, IMT, and stress ECG for CAD prognosis.

Methods and Results

A total of 103 consecutive patients (62 ± 9 years old, 79 men) with clinically suspected CAD had FMD and nitroglycerin-induced dilation (NTG-D) in the BA, carotid artery IMT measurement using high-resolution ultrasound, and exercise treadmill testing. The 73 CAD patients and 30 normal coronary patients were followed for 50 ± 15 months. Fifteen patients had coronary events during this period (1 cardiac death, 2 non-fatal myocardial infarctions, 3 acute heart failures, and 9 unstable anginas). On Kaplan-Meier analysis, only FMD and stress ECG were significant predictors for cardiac events.

Conclusion

Brachial endothelial function as reflected by FMD and conventional exercise stress testing has comparable prognostic value, whereas carotid artery plaque burden appears to be less powerful for predicting future cardiac events.