Endothelial function predicts future development of coronary artery disease: a study of women with chest pain and normal coronary angiograms

Long-term association of brachial artery flow-mediated vasodilation and cardiovascular events in middle-aged subjects with no apparent heart disease

BACKGROUND

Endothelial dysfunction is considered an important prognostic factor in atherosclerosis. The aim of this study was to detect the long-term association of peripheral vascular endothelial function and clinical outcome in healthy subjects without apparent coronary artery disease (CAD).

METHODS

We prospectively assessed brachial flow-mediated dilation (FMD) in 435 consecutive healthy subjects: 281 (65%) men, mean age 54+/-12 years and body mass index 28+/-4 kg/m(2). After overnight fasting and discontinuation of all medications for > or =12 h, FMD and endothelium-independent nitroglycerin-mediated vasodilation were assessed using high resolution linear array ultrasound.

RESULTS

Subjects were divided into 2 groups: below (n=221) and above (n=214) the median FMD of 10.7%, and were comparable regarding CAD risk factors, lipoproteins, fasting glucose, C-reactive protein, and concomitant medications, with a mean clinical follow-up of 32+/-2 months. Composite cardiovascular endpoints (all-cause mortality, non-fatal myocardial infarction, heart failure or angina pectoris hospitalization, stroke, coronary artery bypass grafting and percutaneous coronary interventions) were significantly more common in subjects with below median FMD of 10.7%, than above (11.8% vs 4.7%, p=0.007, respectively). Univariate analysis demonstrated that median FMD significantly predicted cardiovascular events [odds ratio (OR) of 2.78 and 95% CI 1.35 to 5.71 (p=0.003)]. After multivariate analysis including conventional CAD risk factors, median FMD was the best independent predictor of long-term cardiovascular adverse events [OR of 2.70 and 95% CI 1.16 to 6.32 (p=0.011)].

CONCLUSIONS

Brachial artery median FMD independently predicts long-term adverse cardiovascular events in healthy subjects in addition to traditional risk factor assessment.

Analysis of structural changes in normal and aneurismal human aortic tissues using FTIR microscopy

Aortic aneurisms are frequently asymptomatic but can induce dramatic complications. The diagnosis is only based on the aortic diameter and not on a structural and compositional basis. In this preliminary study, we propose infrared microspectroscopy to nondestructively probe normal and aneurismal human aortas. Spectra from 19 human ascending aortic biopsies (10 normal and 9 aneurismal) were acquired using infrared microspectroscopy. A 1500 x 150 microm(2) area of each 7-microm thick cryosection was investigated using a 30-microm spatial resolution with a total of about 200 spectra per sample. Spectral differences between normal and aneurismal tissues were mainly located in spectral regions related to proteins, such as elastin and collagen, and proteoglycans (1750-1000 cm(-1)). Tissue heterogeneity and sample classification have been evaluated using hierarchical cluster analysis of individual or mean spectra and their second derivative. Using spectral range related to proteins, 100% of good classification was obtained whereas the proteoglycan spectral range was less discriminant. This in vitro study demonstrates the potential of such technique to differentiate between normal and aneurismal aortas using selected spectral ranges. Future investigations will be focused on these specific spectral regions to determine the role of elastin and collagen in the discrimination of normal and pathological aortas.

Noninvasive assessment of coronary microvascular function in women at risk for ischaemic heart disease

The primary objective of the current review is to describe the assessment of coronary microvascular function by noninvasive imaging techniques in women at risk for and with ischaemic heart disease (IHD). The search criteria were the analyses of the related bibliography published in PUBMED database. Normal or minimal obstructive coronary artery disease (CAD) at angiography is a common finding in women with signs of ischaemia. Up to 50% of them will have coronary microvascular dysfunction, suggesting that the mechanism of ischaemia may be localised at coronary microcirculation level. Noninvasive measurements of coronary microvascular function can be performed by radionuclide techniques. In particular, positron emission tomography (PET) measures myocardial blood flow (MBF) not only relatively but also in absolute units. Thus, PET offers the possibility to uncover microvascular dysfunction even in patients without obstructive CAD. PET-derived estimates of MBF showed an abnormal coronary microvascular function in women with chest pain and non-obstructive CAD and in women with high-risk conditions for CAD. Interestingly, there is a relationship between an abnormal coronary vascular function and adverse cardiovascular outcomes. In particular, this significant relationship was observed with measurements related to endothelial function. Recent evidence suggests that vascular dysfunction plays a central role as an estimator of outcomes in women at risk for or with IHD. Therefore, assessment of coronary vascular function in these women appears to be of clinical relevance. Whether such evaluation may have an impact to reduce cardiac events needs further investigation.

A novel genetic marker for coronary spasm in women from a genome-wide single nucleotide polymorphism analysis

OBJECTIVE

Coronary spasm plays an important role in the pathogenesis of variant angina and also ischemic heart diseases in general, and it is more likely to occur in angiographically normal coronary arteries than in stenotic coronary arteries. We previously found a -786T/C polymorphism in the 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene and reported that this polymorphism is associated with coronary spasm. We report on an investigation of the genetic factor(s) associated with coronary spasm utilizing a genome-wide case-control study.

METHODS AND RESULTS

We recruited 411 consecutive Japanese women (201 with coronary spasm; 210 controls) who were all underwent an acetylcholine provocation test. For single nucleotide polymorphism analysis (SNP), 116,204 SNPs were genotyped for 100 women (50 with coronary spasm; 50 controls) utilizing the Affymetrix GeneChip 100 K Set. Case-control studies were performed with 311 women (151 with coronary spasm; 160 controls) using the 10 lowest permutation P value SNPs from the initial SNP analysis. Finally, we discovered SNP rs10498345, a genetic marker for coronary spasm in Japanese women (Odds ratio=0.43, P=9.48x10(-7)). Haplotype analysis showed that haplotype H2, the only haplotype containing the protective A allele at SNP rs10498345, was most strongly associated with coronary spasm (permutation P value <1x10(-4)). SNP rs10498345 was strongly associated with the vasoconstrictor response to acetylcholine. Northern blot analysis revealed a novel 4.7 kb RNA transcript, which lacked poly (A), nearby SNP rs10498345.

CONCLUSIONS

SNP rs10498345 was strongly associated with coronary spasm in Japanese women utilizing genome-wide SNP analysis.

Insulin resistance and endothelial cell dysfunction: studies in mammalian models

Type 2 diabetes and obesity are major risk factors for the development of cardiovascular atherosclerosis. Resistance to the metabolic effects of insulin on its traditional target tissues (muscle, liver and adipose tissue) is a central pathogenic feature of these disorders. However, the role of insulin resistance in non-canonical tissues, such as the endothelium, is less clear. Several large studies support a role for insulin resistance in the development of premature cardiovascular atherosclerosis independent of type 2 diabetes and obesity. A key step in the initiation and progression of atherosclerosis is a reduction in the bioactivity of endothelial cell-derived nitric oxide. Nitric oxide is a signalling molecule which has a portfolio of potential antiatherosclerotic effects. The presence of insulin receptors on endothelial cells is well documented, and the endothelium has now emerged as a potentially important target tissue for insulin, with insulin-stimulated production of nitric oxide a feature of the action of insulin on endothelial cells. The role of insulin resistance at the level of the endothelial cell in vascular pathophysiology is unclear. A number of studies in humans and gene-modified mice have demonstrated a close association between insulin resistance and nitric oxide bioactivity. In this review, we discuss the link between insulin resistance and endothelial cell function in humans and demonstrate the complimentary information provided by murine models of obesity and insulin resistance in our understanding of the vasculopathy associated with type 2 diabetes and obesity.

Accelerated endothelial dysfunction in mild prediabetic insulin resistance: the early role of reactive oxygen species

Insulin resistance is well established as an independent risk factor for the development of type 2 diabetes and cardiovascular atherosclerosis. Most studies have examined atherogenesis in models of severe insulin resistance or diabetes. However, by the time of diagnosis, individuals with type 2 diabetes already demonstrate a significant atheroma burden. Furthermore, recent studies suggest that, even in adolescence, insulin resistance is a progressive disorder that increases cardiovascular risk. In the present report, we studied early mechanisms of reduction in the bioavailability of the antiatheroscerotic molecule nitric oxide (NO) in very mild insulin resistance. Mice with haploinsufficiency for the insulin receptor (IRKO) are a model of mild insulin resistance with preserved glycemic control. We previously demonstrated that 2-mo-old (Young) IRKO mice have preserved vasorelaxation responses to ACh. This remained the case at 4 mo of age. However, by 6 mo, despite no significant deterioration in glucose homeostasis (Adult), IRKO mice had marked blunting of ACh-mediated vasorelaxation [IRKO maximum contraction response (E(max)) 66 +/- 5% vs. wild type 87 +/- 4%, P < 0.01]. Despite the endothelial dysfunction demonstrated, aortic endothelial nitric oxide synthase (eNOS) mRNA levels were similar in Adult IRKO and wild-type mice, and, interestingly, aortic eNOS protein levels were increased, suggesting a compensatory upregulation in the IRKO. We then examined the potential role of reactive oxygen species in mediating early endothelial dysfunction. The superoxide dismutase mimetic Mn(III)tetrakis(1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP) restored ACh relaxation responses in the Adult IRKO (E(max) to ACh with MnTMPyP 85 +/- 5%). Dihydroethidium fluorescence of aortas and isolated coronary microvascular endothelial cells confirmed a substantial increase in endothelium-derived reactive oxygen species in IRKO mice. These data demonstrate that mild insulin resistance is a potent substrate for accelerated endothelial dysfunction and support a role for endothelial cell superoxide production as a mechanism underlying the early reduction in NO bioavailability.

The endothelial nitric oxide synthase gene -786T/C polymorphism is a predictive factor for reattacks of coronary spasm

OBJECTIVE

We previously found a -786T/C polymorphism in the 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene and reported that this polymorphism is strongly associated with coronary spasm. In this study, we examined whether the polymorphism is a prognostic marker in coronary spasm patients.

METHODS AND RESULTS

We examined the clinical courses of 201 consecutive patients with coronary spasm who were admitted to our institution: 146 patients with the -786T/T genotype; 50 patients with the -786C/T genotype; and five patients with the -786C/C genotype. The mean follow-up period was 76+/-60 months. All the patients took calcium channel blockers and/or nitrate during the follow-up period. In this study, no patients died due to a cardiac event. About 25 patients were readmitted owing to cardiovascular disease. Out of these 25 patients, 23 patients were readmitted owing to a reattack of coronary spasm. The -786C allele was significantly associated with readmission due to coronary spasm (P=0.0072, odds ratio: 3.37 in the dominant effect). Kaplan-Meier analysis revealed that the occurrence of readmission was significantly higher in the patients with the -786C allele than in the patients without the -786C allele (P=0.0079). Further, multiple logistic regression analysis revealed that the -786T/C polymorphism was an independent predictor for readmission due to reattack of coronary spasm (P=0.006; relative risk=3.590).

CONCLUSIONS

The eNOS -786C allele is an independent risk factor for readmission due to a recurrent attack of coronary spasm in patients with coronary spasm, even if the patients have taken calcium channel blockers and/or nitrate.

Positron emission tomography in coronary artery disease

PURPOSE OF REVIEW

Mortality and coronary events are dramatically reduced in coronary artery disease by intense lifestyle and pharmacologic management without further improvement by revascularization procedures, thereby requiring definitive noninvasive diagnostic imaging. Consequently, this review summarizes the evidence supporting cardiac positron emission tomography as a definitive, noninvasive, 'one-stop' test for routine management of coronary artery disease that is well validated in the scientific literature and illustrated by clinical cases.

RECENT FINDINGS

Substantial evidence documents accuracy of positron emission tomography for identifying early or advanced coronary artery disease, quantifying its severity, risk stratification, deciding on revascularization procedures, following progression or regression and for evaluating coronary endothelial function as the basis for preventive treatment. Recent technology like positron emission tomography-computed tomography, however, requires advanced knowledge, training and attention to technical details to avoid common artifactual results and to provide definitive conclusions illustrated in this review.

SUMMARY

Cardiac positron emission tomography, done correctly with attention to technical details, provides definitive noninvasive assessment of early or advanced coronary atherosclerosis as the basis for invasive procedures or for lifelong intense risk factor management, demonstrates progression or regression of disease, predicts clinical outcomes and serves as the primary definitive noninvasive guide for managing coronary artery disease.

Endothelial dysfunction in Turkish patients with non-alcoholic fatty liver disease

BACKGROUND

The components of the metabolic syndrome are closely related with endothelial dysfunction, which is a pathophysiological issue of cardiovascular diseases. Non-alcoholic fatty liver disease (NAFLD) is considered as one of the components of the metabolic syndrome. The aim of this study was to evaluate the endothelial-dependent dilatation (EDD) and endothelial-independent dilatation (EID) of the brachial artery in NAFLD.

METHODS

Fifteen non-alcoholic steatohepatitis (NASH), 17 patients with simple steatosis and 16 healthy subjects formed the study group. Non-alcoholic fatty liver disease group was composed of patients admitted to the gastroenterology outpatient clinic because of increased liver enzymes. Endothelial functions of the brachial artery were evaluated by vascular ultrasound. EDD was assessed by establishing reactive hyperaemia, and EID was determined by using sublingual nitrate.

RESULTS

No statistical difference for the basal diameter of brachial artery was found between the groups (P = 0.49). The values for EDD and EID were significantly different across all three groups (P < 0.0001 and P < 0.0001, respectively). EDD and EID were significantly lower in NASH compared with simple steatosis (P = 0.01 and P < 0.01, respectively). However, there was no statistical significance for EDD and EID in simple steatosis groups compared with controls (P = 0.58 and P = 0.98, respectively).

CONCLUSIONS

Our study showed that patients with NASH had significantly worse endothelial dysfunction compared with patients with simple steatosis and healthy subjects. The treatment strategies with ameliorative effects for endothelial dysfunction might be effective for delaying the development of cardiovascular complications in NAFLD.

Dilatação fluxo-mediada da artéria braquial em mulheres com artrite reumatóide

OBJETIVO: Avaliar a função endotelial em pacientes com artrite reumatóide, pela dilatação fluxo-mediada da artéria braquial. MATERIAIS E MÉTODOS: Sessenta e oito pacientes, sendo 32 com artrite reumatóide e 36 do grupo controle, foram avaliadas pela dilatação fluxo-mediada da artéria braquial (método ultra-sonográfico, no modo B, de avaliação de risco cardiovascular). Em um segundo tempo, foi avaliada a correlação entre a dilatação fluxo-mediada da artéria braquial, a proteína C reativa e o tempo de doença em pacientes com artrite reumatóide. RESULTADOS: A dilatação fluxo-mediada da artéria braquial na artrite reumatóide foi igual a 5,6 ± 9,69% e no grupo controle foi igual a 23,24 ± 5,65%, diferença estatisticamente significante (p < 0,00001). A proteína C-reativa teve resultado de 4,8 ± 9,1 mg/l. A correlação entre a idade, a dilatação fluxo-mediada da artéria braquial e a proteína C reativa nas pacientes com artrite reumatóide não mostrou resultado estatisticamente significante. CONCLUSÃO: Mulheres com artrite reumatóide apresentam importante disfunção endotelial quando comparadas com mulheres normais.

Prognosis of stable angina pectoris: why we need larger population studies with higher endpoint resolution

The prognosis of angina was described as "unhappy" by the Framingham investigators and as little different from that of 1-year survivors of acute myocardial infarction. Yet recent clinical trials now report that angina has a good prognosis with adverse outcomes reduced to "normal levels". These disparate prognostic assessments may not be incompatible, applying as they do to population cohorts (Framingham) and selected participants in clinical trials. Comparisons between studies are further complicated by the absence of agreed case definitions for stable angina (contrast this with acute coronary syndromes). Our recent data show that for patients with recent onset symptoms attending chest pain clinics, angina remains a high-risk diagnosis and although many patients receive symptomatic benefit from revascularisation, prognosis is usually unaffected. This leaves little room for complacency and, with angina the commonest initial manifestation of coronary artery disease, there is the opportunity for early detection, risk stratification and treatment to modify outcomes. Meanwhile, larger population-based studies are needed to define the patient journey from earliest presentation through the various syndrome transitions to coronary or noncardiac death in order to increase understanding of the aetiological and prognostic differences between the different coronary disease phenotypes.

The elusive prognostic value of systemic endothelial function in patients with chest pain syndrome

The prognostic value of systemic endothelial dysfunction still remains uncertain in ischemic heart disease. The aim of the study was to establish the prognostic value of ultrasonically assessed systemic endothelial dysfunction in patients with chest pain syndrome and to assess whether this information was incremental to that already provided by simple parameters derived from echocardiography, such as left ventricular mass index or ejection fraction. One hundred ninety-five in-hospital patients (age=60+/-10 years; 63 females) with known or suspected CAD have been enrolled. All of the patients underwent, on different days, coronary angiography, endothelium-dependent FMD testing of the brachial artery by high-resolution ultrasound and resting 2D-echocardiography evaluation. The result of the FMD has been defined as the percent change in the internal diameter of the brachial artery during reactive hyperemia related to baseline. All patients were followed-up for a median of 27 months. During follow-up there were 17 deaths (9 cardiac), 4 non-fatal myocardial infarction (MI), and 18 late clinically-driven revascularization procedures. By a multivariate analysis, echocardiographically assessed ejection fraction (odds ratio: 2.32; 95% confidence interval: 1.24-4.33; p=0.008) and angiographically assessed CAD (odds ratio: 2.82; 95% confidence interval: 1.40-5.67; p=0.003), were independent prognostic predictors of events. In patients with known or suspected CAD, systemic endothelial dysfunction did not show a significant prognostic value. Echocardiographic indices of structural left ventricular damage appear to have a stronger prognostic value than functional indices of peripheral vascular damage in risk stratifying ischemic patients.

Vascular endothelial function and circulating endothelial progenitor cells in patients with cardiac syndrome X

BACKGROUND

Endothelial dysfunction and microvascular abnormalities have been reported in patients with cardiac syndrome X (CSX), but the underlying mechanisms are unclear. Recent insights suggest that the injured endothelial monolayer is regenerated by circulating bone marrow-derived endothelial progenitor cells (EPCs).

AIM

To test the hypothesis that the biology of altered EPCs might contribute to the pathophysiology of CSX.

METHODS

34 subjects (mean (SD) age: 62 (7) years) were enrolled in the study, including 12 patients with CSX, 12 stable subjects with coronary artery disease (CAD) and 10 healthy controls. The number and adhesive function of EPCs were measured in peripheral-blood samples from these study participants.

RESULTS

The baseline characteristics in patients with CSX and CAD were enhanced Framingham risk scores, more hypertension and lower high-density lipoproteins than the controls. Patients with CSX and CAD had significantly decreased endothelium-dependent flow-mediated vasodilation (FMD) compared with normal controls (normal controls vs CSX vs CAD: 10.6% (3.5%) vs 6.1% (1.8%) vs 4.1% (1.9%), p<0.001), but the difference was not found in endothelium-independent nitroglycerine-mediated vasodilation (p = 0.159). Reduced numbers of colony-forming units (CFU) of EPCs were noted in patients with CSX and CAD (normal vs CSX vs CAD: 41 (9) vs 30 (7) vs 14 (7) CFU/well, p<0.001). Levels of EPCs were shown to be associated with FMD (r = 0.557, p = 0.001) and high-density lipoprotein (r = 0.339, p = 0.049). Also, attenuated fibronectin adhesion function of EPCs was found in patients with CSX and CaD compared with normal subjects (104 (12) vs 80 (20) vs 65 (13)/well, p<0.001).

CONCLUSIONS

This study clearly showed for the first time that compared with normal subjects, patients with CSX have decreased levels and adhesive function of circulating EPCs. These findings may explain the underlying mechanisms which contribute to the endothelial dysfunction and microvascular abnormalities observed in patients with CSX.

Mutation of the circadian clock gene Per2 alters vascular endothelial function

BACKGROUND

The circadian clock regulates biological processes including cardiovascular function and metabolism. In the present study, we investigated the role of the circadian clock gene Period2 (Per2) in endothelial function in a mouse model.

METHODS AND RESULTS

Compared with the wild-type littermates, mice with Per2 mutation exhibited impaired endothelium-dependent relaxations to acetylcholine in aortic rings suspended in organ chambers. During transition from the inactive to active phase, this response was further increased in the wild-type mice but further decreased in the Per2 mutants. The endothelial dysfunction in the Per2 mutants was also observed with ionomycin, which was improved by the cyclooxygenase inhibitor indomethacin. No changes in the expression of endothelial acetylcholine-M3 receptor or endothelial nitric oxide synthase protein but increased cyclooxygenase-1 (not cyclooxygenase-2) protein levels were observed in the aortas of the Per2 mutants. Compared with Per2 mutants, a greater endothelium-dependent relaxation to ATP was observed in the wild-type mice, which was reduced by indomethacin. In quiescent aortic rings, ATP caused greater endothelium-dependent contractions in the Per2 mutants than in the wild-type mice, contractions that were abolished by indomethacin. The endothelial dysfunction in the Per2 mutant mice is not associated with hypertension or dyslipidemia.

CONCLUSIONS

Mutation in the Per2 gene in mice is associated with aortic endothelial dysfunction involving decreased production of NO and vasodilatory prostaglandin(s) and increased release of cyclooxygenase-1-derived vasoconstrictor(s). The results suggest an important role of the Per2 gene in maintenance of normal cardiovascular functions.

Pioglitazone produces rapid and persistent reduction of vascular inflammation in patients with hypertension and type 2 diabetes mellitus who are receiving angiotensin II receptor blockers

Inhibition of the renin-angiotensin system reportedly exerts potent antiatherogenic effects by reducing vascular inflammation. We tested the hypothesis that pioglitazone, a peroxisome proliferator-activated receptor gamma agonist, further reduces vascular inflammation in patients receiving angiotensin II receptor blockers. Patients with hypertension who had developed type 2 diabetes mellitus were randomly assigned to receive either pioglitazone (15 mg/d, n = 20) or voglibose, an alpha-glucosidase inhibitor (0.6 mg/d, n=19) for 6 months, and changes in their serum concentrations of C-reactive protein (CRP), intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) were monitored. Pioglitazone, but not voglibose, reduced CRP levels within 1 month (-51%+/-7%, mean+/-SEM; P<.001). C-reactive protein levels were decreased after 6 months of treatment with either pioglitazone or voglibose, with the former being more effective (-57%+/-8% vs -9%+/-18%; P<.05). The levels of ICAM-1 and VCAM-1 were significantly reduced after 1 month of pioglitazone therapy (-9%+/-3% and -8%+/-3%, respectively; both P<.05), with the beneficial effects persisting throughout the study period. In contrast, the levels of ICAM-1 and VCAM-1 were not altered during the study period in patients on voglibose. There was no correlation between the reduction of hemoglobin A1c and that of CRP, ICAM-1, or VCAM-1. These results suggest that augmentation with pioglitazone further reduces vascular inflammation in patients with hypertension and diabetes who are receiving angiotensin II receptor blockers. This may contribute to the reduction of cardiovascular events in this at-risk population.

Transgenic expression of a dominant negative K(ATP) channel subunit in the mouse endothelium: effects on coronary flow and endothelin-1 secretion

K(ATP) channels are involved in regulating coronary function, but the contribution of endothelial K(ATP) channels remains largely uncharacterized. We generated a transgenic mouse model to specifically target endothelial K(ATP) channels by expressing a dominant negative Kir6.1 subunit only in the endothelium. These animals had no obvious overt phenotype and no early mortality. Histologically, the coronary endothelium in these animals was preserved. There was no evidence of increased susceptibility to ergonovine-induced coronary vasospasm. However, isolated hearts from these animals had a substantially elevated basal coronary perfusion pressure. The K(ATP) channel openers, adenosine and levcromakalim, decreased the perfusion pressure whereas the K(ATP) channel blocker glibenclamide failed to produce a vasoconstrictive response. The inducible endothelial nitric oxide pathway was intact, as evidenced by vasodilation caused by bradykinin. In contrast, basal endothelin-1 release was significantly elevated in the coronary effluent from these hearts. Treatment of mice with bosentan (endothelin-1 receptor antagonist) normalized the coronary perfusion pressure, demonstrating that the elevated endothelin-1 release was sufficient to account for the increased coronary perfusion pressure. Pharmacological blockade of K(ATP) channels led to elevated endothelin-1 levels in the coronary effluent of isolated mouse and rat hearts as well as enhanced endothelin-1 secretion from isolated human coronary endothelial cells. These data are consistent with a role for endothelial K(ATP) channels to control the coronary blood flow by modulating the release of the vasoconstrictor, endothelin-1.

Angina, "normal" coronary angiography, and vascular dysfunction: risk assessment strategies

The authors discuss how to stratify risk in patients with chest pain and a normal coronary angiogram.

Asymmetric dimethylarginine and reduced nitric oxide bioavailability in young Black African men

Black Africans have a higher incidence of cardiovascular disease than white Europeans. We explored potential mechanisms of this excess risk by assessing endothelium function, inflammatory status (C-reactive protein), oxidative stress (isoprostane-F2alpha), and plasma asymmetrical dimethyl arginine (ADMA; an endogenous competitive inhibitor of NO synthase) in each ethnic group. Thirty healthy black Africans and 28 well-matched white European male subjects were studied (mean age+/-SE: 32.2+/-0.9 and 29.2+/-1.2 years, respectively; P=0.07). High-resolution ultrasound was used to assess vascular function in the brachial artery by measuring flow mediated dilatation ([percentage of change]; endothelium-dependent function) and glyceryltrinitrate dilatation ([percentage of change]; endothelium-independent function). Blood pressure, fasting lipids, glucose, and estimated glomerular filtration rate levels were similar in both groups. There was no difference in C-reactive protein (black Africans: 0.8+/-0.1 mg/L; white Europeans: 0.6+/-0.1 mg/L; P=0.22), isoprostane-F2alpha (black Africans: 42.9+/-1.5 pg/mL; white Europeans: 39.2+/-1.5 pg/mL; P=0.23), and leptin (black Africans: 64.1+/-10.2 ng/mL; white Europeans: 47.8+/-9.8 ng/mL; P=0.37) levels between the 2 ethnic groups. However, compared with white Europeans, plasma ADMA levels were significantly higher in black Africans (0.34+/-0.02 micromol/L and 0.25+/-0.03 micromol/L; P=0.03). There was no difference in the percentage of glyceryltrinitrate dilatation (P=0.7), but the percentage of flow-mediated dilatation was significantly lower in black Africans (black Africans: 5.2+/-0.3; white Europeans: 6.3+/-0.4; P=0.02). In a stepwise multiple regression model, ADMA level was the only independent determinant of flow-mediated dilatation (P=0.02). In turn, race was the only independent determinant of ADMA levels (P=0.03). Our findings indicate that circulating ADMA levels are significantly higher in healthy black African males than in white European males. This may contribute to the lower NO bioavailability and higher incidence of cardiovascular disease seen in black Africans.

A long-term "memory" of HIF induction in response to chronic mild decreased oxygen after oxygen normalization

Background

Endothelial dysfunction (ED) is functionally characterized by decreased vasorelaxation, increased thrombosis, increased inflammation, and altered angiogenic potential, has been intimately associated with the progression and severity of cardiovascular disease. Patients with compromised cardiac function oftentimes have a state of chronic mild decreased oxygen at the level of the vasculature and organs, which has been shown to exacerbate ED. Hypoxia inducible factor (HIF) is a transcription factor complex shown to be the master regulator of the cellular response to decreased oxygen levels and many HIF target genes have been shown to be associated with ED.

Methods

Human endothelial and aortic smooth muscle cells were exposed either to A) normoxia (21% O₂) for three weeks, or to B) mild decreased oxygen (15% O₂) for three weeks to mimic blood oxygen levels in patients with heart failure, or to C) mild decreased oxygen for two weeks followed by one week of normoxia ("memory" treatment). Levels of HIF signaling genes (HIF-1α, HIF-2α, VEGF, BNIP3, GLUT-1, PAI-1 and iNOS) were measured both at the protein and mRNA levels.

Results

It was found that chronic exposure to mild decreased oxygen resulted in significantly increased HIF signaling. There was also a "memory" of HIF-1α and HIF target gene induction when oxygen levels were normalized for one week, and this "memory" could be interrupted by adding a small molecule HIF inhibitor to the last week of normalized oxygen. Finally, levels of ubiquitylated HIF-1α were reduced in response to chronic mild decreased oxygen and were not full restored after oxygen normalization.

Conclusion

These data suggest that HIF signaling may be contributing to the pathogenesis of endothelial dysfunction and that normalization of oxygen levels may not be enough to reduce vascular stress.

The association between right coronary artery morphology and endothelial function

BACKGROUND

Two distinct right coronary artery (RCA) morphologies have been previously described: sigma- and C-shaped RCAs. While the C-shaped RCA was significantly associated with atherosclerosis, the sigma-shaped was not. The association of RCA morphology and vascular endothelial function has not yet been assessed.

METHODS

To evaluate the association between the RCA's morphology and flow-mediated endothelium-dependent dilation (FMD) in patients without evidence of atherosclerotic lesions, we prospectively assessed FMD in 49 consecutive patients with non-specific chest pain, who were referred to our laboratory 30+/-10 days after corroboration of normal coronary arteries on coronary angiography. Endothelium-dependent brachial artery FMD and endothelium-independent nitroglycerin-mediated vasodilation (NTG) were assessed using high resolution (15 MHz) linear array ultrasound. The patients were divided into 2 groups according to their RCA morphology on coronary angiograms (sigma and C) which were analyzed by 2 independent readers who were blinded to the patients' FMD results.

RESULTS

The C-shaped group exhibited a significantly lower FMD compared to the sigma-shaped group (9.0+/-4.2% vs. 14.3+/-4.7%, p<0.04, respectively), while NTG was the same in both groups. There were no significant group differences in other variables.

CONCLUSIONS

Endothelium-dependent FMD in the brachial artery is significantly greater in sigma- compared to C-shaped RCA in coronary arteries without overt atherosclerotic lesions, suggesting a potential mechanism whereby C-shaped RCA are predisposed to atherosclerosis.

Elderly Women Diagnosed with Nonspecific Chest Pain May Be at Increased Cardiovascular Risk

BACKGROUND

Women are more likely than men to have nonspecific chest pain (NSCP) symptoms. The long-term outcomes in women discharged with a diagnosis of NSCP are unknown.

METHODS

The Women's Health Initiative Observational Study enrolled postmenopausal women aged 50-79 years. After excluding those with prior cardiovascular disease (CVD), 83,622 women were studied. NSCP cases were defined as having an initial primary hospital discharge diagnosis of NSCP (ICD-9 codes 786.50, 786.51, 786.59) without a prior diagnosis of coronary heart disease (CHD). Risks of subsequent CHD events were estimated from Cox proportional hazard ratio (HR) models stratified by clinic and adjusted for baseline age, cardiovascular risk factors, and hormone use.

RESULTS

Over an average of 8 years of follow-up, 11% (230 of 2,092) of women with NSCP experienced a cardiovascular event compared with 9.5% (7,724 of 81,530) who did not. Compared with women without a hospitalization for NSCP during follow-up, those with NSCP had a greater than 2-fold higher risk of a subsequent hospitalization for clinically diagnosed angina (HR 2.18, 95% CI 1.66-2.86) and at least a 1.5-fold higher risk of nonfatal myocardial infarction (MI) (HR 1.59, 1.10-2.31), revascularization (HR 1.67, 1.28-2.20), and congestive heart failure (HR 1.75, 1.27-2.41). Women with NSCP who subsequently experienced a CHD event were more likely to be over age 65 or to have cardiovascular risk factors.

CONCLUSIONS

Older women discharged with a diagnosis of NSCP may be at increased risk of CHD morbidity. Further research is needed to replicate these findings in other populations.

Endothelial arginase: a new target in atherosclerosis

Decreased endothelial nitric oxide (NO) bioavailability as it relates to endothelial dysfunction plays an important role in various cardiovascular disorders, including athero-sclerosis. Recent research has provided evidence that endothelial dysfunction in atherosclerosis is not primarily caused by decreased endothelial NO synthase (eNOS) gene expression, but rather deregulation of eNOS enzymatic activity, which contributes to the increased oxidative stress in atherosclerosis. Among other mechanisms, the substrate L-arginine is an important limiting factor for NO production. Emerging evidence demonstrates that L-arginine is not only converted to NO via eNOS, but also metabolized to urea and l-ornithine via arginase in endothelial cells. Hence, arginase competes with eNOS for the substrate L-arginine, resulting in deceased NO production. There are an increasing number of studies showing that enhanced arginase gene expression and/or activity contribute to endothelial dysfunction in various cardiovascular disorders, including atherosclerosis. Thus, endothelial arginase may represent a new therapeutic target in atherosclerosis.

Brachial reactivity and extent of coronary artery disease in patients with first ST-elevation acute myocardial infarction

We examined peripheral endothelial function, as measured by brachial artery reactivity, in 49 stable patients with a first episode of acute ST-segment elevation myocardial infarction to examine the relation between extent of coronary disease and peripheral vascular reactivity. Brachial artery reactivity was assessed by ultrasound and flow-mediated dilation (FMD) was calculated as the change in brachial artery diameter after release of suprasystolic blood pressure cuff inflation. FMD was classified as abnormal in (< or =6%) 19 patients (group 1) and as normal in 30 patients (group 2). Average FMDs were 2 +/- 2% in group 1 and 11 +/- 4% in group 2. Patients in group 1 were older (62 +/- 5 vs 54 +/- 11 years, p = 0.02) and more often had a history of hypertension (n = 10, 52%, vs 6, 20%, p = 0.017). Patients with abnormal endothelial function (group 1) had a larger number of coronary obstructive (>or =50%) lesions (3.6 +/- 2.4 vs 2.0 +/- 1.7, p = 0.01) and more extensive coronary disease (1.9 +/- 0.8 vs 1.4 +/- 0.8 vessel disease, p = 0.05). In patients with 3-vessel disease, FMD was lower (4.0 +/- 1.8% vs 8.2 +/- 0.8%, p = 0.04) than in those with lesser coronary involvement. In conclusion, in patients with a first episode of ST-segment elevation myocardial infarction, there was a strong correlation between extent of coronary artery disease and brachial artery reactivity. Patients with localized coronary disease had relatively normal brachial reactivity, whereas those with diffuse coronary disease had more severe abnormal brachial artery reactivity.

Cardiac syndrome X and endothelial dysfunction: new concepts in prognosis and treatment

Cardiac syndrome X (CSX), or angina with no flow-limiting stenosis on coronary angiogram, has been regarded as a condition with an excellent prognosis despite variable symptomatic improvement. Newer data show that patients with CSX with endothelial dysfunction have an increased risk for future adverse cardiac events. Current hypotheses of CSX pathophysiology emphasize a dysfunctional vascular endothelium that leads to microvascular ischemia. Treatments that target improving endothelial function, such as statins, angiotensin-converting enzyme inhibitors, estrogen, and lifestyle modification, are promising additions to treatment regimens for CSX. The goal of this article is to provide information for improved diagnosis, risk stratification, and therapy for the population with CSX.

Divergent effects of angiotensin-converting enzyme inhibition on blood pressure and endothelial function in obese humans

Endothelial dysfunction is a pivotal early event in the development of atherosclerosis and a characteristic feature of obesity. This study was designed to investigate the effect of angiotensin-converting enzyme (ACE) inhibition on endothelial function in people who were obese but otherwise healthy. We performed a double-blind, randomised, placebo-controlled study examining the effect of the ACE inhibitor perindopril (4 mg per day) on flow-mediated vasodilatation (FMD) of the brachial artery, arterial blood pressure, glucose homeostasis and inflammatory cytokines. Eighteen obese subjects (all body mass index > 30 kg/m2) were randomised to receive perindopril or placebo for four weeks. Perindopril led to a fall in systolic blood pressure from 131 (standard error of mean [SEM] 3) to 117(5) mmHg and diastolic blood pressure from 74(4) mmHg to 68(4) mmHg, both p<0.001. Despite this fall in blood pressure, ACE inhibition had no effect on FMD, 8.2 (1.2)% versus 8.3 (1.5)%, p=0.9. ACE inhibition had no effect on insulin, lipids or circulating cytokines. In healthy obese humans, despite a significant reduction in blood pressure, ACE inhibition had no effect on FMD.

Recent advances in understanding endothelial dysfunction in atherosclerosis

Over the last two decades, it has become evident that decreased bioavailability of endothelial nitric oxide (NO) produced from endothelial NO synthase (eNOS), referred to as endothelial dysfunction, plays a crucial role in the development and progression of atherosclerosis. Much progress has been made in understanding the mechanisms of decreased endothelial NO bioavailability at the levels of regulation of eNOS gene expression, eNOS enzymatic activity and NO inactivation. Initial studies suggest that increasing eNOS gene expression would improve endothelial NO release in the hope of inhibiting the progression of atherosclerosis. Recent experimental studies, however, do not always support this therapeutic concept and show some evidence that overexpression of eNOS in atherosclerosis may be even harmful for the disease progression.Thus, recent research to improve endothelial function in atherosclerosis has focused on regulation of eNOS enzymatic activity and prevention of NO inactivation by oxidative stress. Since the role of oxidative stress in endothelial NO bioavailability has been reviewed in a large number of comprehensive articles, this article focuses on the relevant regulatory mechanisms of eNOS enzymatic activity that are emerging to play a role in endothelial dysfunction in atherosclerosis.

Endothelial function and the prediction of CVD in diabetes

Endothelial dysfunction has received increasing attention as a potential contributor to the pathogenesis of vascular disease in diabetes mellitus. Technologies to detect endothelial dysfunction include assessment of endothelium-dependent vasodilatation and plasma levels of cell injury markers. Although clinical and epidemiologic studies show associations and potential links between endothelial dysfunction and outcome in diabetes, there is a substantial need for further work.

Comparable prognostic value of vasodilator response to acetylcholine in brachial and coronary arteries for predicting long-term cardiovascular events in suspected coronary artery disease

BACKGROUND

Vasodilator response to acetylcholine (ACh) (ie, endothelium-dependent dilation) is impaired in the peripheral and coronary circulation of patients with coronary risk factors and coronary artery disease (CAD). There is a close relationship of vasodilator response to ACh in both the coronary artery (CA) and the brachial artery (BA), but the comparative prognostic importance of these responses has not been fully investigated in relatively low-risk suspected CAD.

METHODS AND RESULTS

The flow responses of both the CA and BA were measured in 70 patients with suspected CAD, excluding patients with triple-vessel disease and known peripheral or cerebrovascular disorders. A Doppler guidewire was placed into a major branch of the CA and a proximal portion of the left BA. ACh was infused at 10(-8), 10(-7) and 10(-6) mol/L for 3 min into the CA and at 7.5, 15, and 30 mug/min for 5 min into BA. The flow response was obtained by multiplying the average peak velocity by the cross-sectional area from quantitative angiography. Vasodilator response to ACh was assessed by the ratio of ACh-induced flow/baseline flow, expressed as coronary blood flow index (CBFI) or brachial blood flow index (BBFI). There were 39 CAD patients (61 +/- 8 years old) and 31 normal coronary patients (NL, 58 +/- 11 years old) who were followed up for 53 +/- 17 months. Eleven patients had coronary events (CE) during this period: 1 case of nonfatal myocardial infarction and 10 cases of unstable angina. A strong correlation between CBFI and BBFI was observed at middle-and high-doses of ACh (r=0.72, p<0.0001, 15 microg/min vs 10(-7) mol/L; r=0.76, p<0.0001, 30 microg/min vs 10(-6) mol/L). Kaplan-Meier analysis, using the best cut-off values obtained from receiver-operating characteristic curves for CE, revealed that both CBFI and CAFI were significant predictors for CE.

CONCLUSIONS

The BA vasodilator response to optimal ACh dosage can be used as a surrogate prognostic predictor for coronary endothelial function tests in patients with suspected CAD.

Cardiac syndrome X: a critical overview and future perspectives

The classic definition of cardiac syndrome X (CSX) seems inadequate both for clinical and research purposes and should be replaced with one aimed at including a sufficiently homogeneous group of patients with the common plausible pathophysiological mechanism of coronary microvascular dysfunction. More specifically, CSX should be defined as a form of stable effort angina, which, according to careful diagnostic investigation, can reasonably be attributed to abnormalities in the coronary microvascular circulation.

Reduced NAD(P)H Oxidase in Low Renin Hypertension

Endothelial dysfunction (ED) complicates hypertension and is a precursor of atherosclerosis. Reduced NO bioactivity, because of increased reduced NAD(P)H oxidase–derived reactive oxygen species (ROS), plays a critical role in ED. gp91 phox , predominantly expressed in the endothelium and adventitia, is a subunit of NAD(P)H oxidase important for its activation in response to angiotensin (Ang) II. Human atherosclerotic plaques are heavy laden with gp91 phox . We have shown that in Dahl salt-sensitive (DS) rats, a paradigm of low renin salt-sensitive (SS) hypertension in humans, Ang II receptor blockade normalizes ROS production and endothelium-dependent relaxation (EDR) without significantly affecting systolic blood pressure (SBP). To additionally elucidate the mechanisms involved in the functional association of Ang II in SS hypertension, we administered a cell-permeable inhibitor of the assembly of p47 phox with gp91 phox in NAD(P)H oxidase, gp91ds-tat (10 mg/kg body weight, 3 weeks by minipump), to DS rats fed a 4% salt diet. Control rats received either vehicle or an inactive scramb-tat peptide. Vehicle-treated DS developed hypertension (SBP 168±5 mm Hg), left ventricular hypertrophy (LVH), proteinuria, impaired EDR, and increased aortic ROS production (superoxide 115% and peroxynitrite 157%) and expression of the proatherogenic molecules LOX-1 (130%) and MCP-1 (166%). gp91ds-tat, but not scramb-tat, normalized ROS and EDR, as well as LOX-1 and MCP-1, despite nonsignificant effects on SBP (159±5 mm Hg; P >0.05), left ventricular hypertrophy, and proteinuria. Our findings support the notion that in SS hypertension, activation of NAD(P)H oxidase promotes ED and atherogenesis via decreased nitric oxide bioactivity and increased LOX-1 and MCP-1, independent of blood pressure.

The clinical significance of endothelial dysfunction

PURPOSE OF REVIEW

Endothelial dysfunction is thought to play a pivotal role in the development, progression, and clinical complications of atherosclerosis. Several recent studies have addressed the clinical implications of endothelial dysfunction for cardiovascular events, atherosclerosis, restenosis, and heart failure. Novel findings with respect to endothelial progenitor cells and their alteration by cardiovascular risk factors are characterized and potential therapeutic interventions to improve endothelial and endothelial progenitor cell function are discussed.

RECENT FINDINGS

Over the past 5 years evidence has accumulated from clinical studies for a close association of the degree of endothelial dysfunction and clinical cardiovascular events in patients with cardiovascular risk factors, coronary disease, acute coronary syndrome, or heart failure. Understanding of the mechanisms leading to endothelial dysfunction has improved, including the notion that dysfunctional endothelial nitric oxide synthase, in part due to deficiency of the endothelial nitric oxide synthase cofactor tetrahydrobiopterin, likely plays an important role. Major progress has been made in understanding the role of endothelial progenitor cells, which likely contribute to both ischemia-induced neovascularization and endothelial regeneration after injury. Endothelial progenitor cell function is altered in patients with cardiovascular risk factors.

SUMMARY

Recent research on endothelial and endothelial progenitor cell dysfunction supports their clinical significance and has led to important insights in the pathophysiology of cardiovascular disease and at the same time provides an important opportunity to develop novel therapeutic approaches. Endothelial function represents a valuable surrogate endpoint to assess the impact of therapeutic interventions.

Decreased microvascular nitric oxide-dependent vasodilation in postural tachycardia syndrome

BACKGROUND

One variant of postural tachycardia syndrome (POTS), designated low-flow POTS, is associated with decreased peripheral blood flow related to impaired local vascular regulation.

METHODS AND RESULTS

To investigate the hypothesis that microvascular endothelial dysfunction produces decreased peripheral blood flow in low-flow POTS, we performed experiments using laser-Doppler flowmetry (LDF) combined with iontophoresis in 15 low-flow POTS patients, 17 normal-flow POTS patients, and 13 healthy reference volunteers varying in age from 14 to 22 years. We tested whether alpha-adrenergic vasoregulation was impaired using iontophoretic delivery of tyramine, phentolamine, and bretylium followed by a norepinephrine dose response. We tested endothelial-dependent and -independent receptor-mediated vasodilation by measuring acetylcholine and sodium nitroprusside dose responses. We tested whether nitric oxide-dependent vasodilation was different in these groups by testing the local thermal hyperemic response to saline used as a reference compared with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). Adrenergic and receptor-dependent cutaneous vasoregulation was similar for low-flow POTS, normal-flow POTS, and reference subjects. Thermal hyperemia produced distinctly different findings: there was marked attenuation of the nitric oxide-sensitive plateau during prolonged heating, which was insensitive to L-NAME in low-flow POTS subjects. The pattern of thermal hyperemia response in low-flow POTS subjects during saline administration resembled the pattern in reference subjects during L-NAME administration and was minimally affected by L-NAME.

CONCLUSIONS

The data suggest that flow-dependent nitric oxide release is reduced in low-flow POTS. This may account for local flow regulation abnormalities.

Long-term survival of patients with chest pain syndrome and angiographically normal or near-normal coronary arteries: the additional prognostic value of dipyridamole echocardiography test (DET)

AIMS

Patients with normal coronary arteries have a heterogeneous prognosis. Aim of this study was to assess whether dipyridamole stress echocardiography positivity identifies a prognostically less benign subset.

METHODS AND RESULTS

We selected 457 patients (245 males; 56+/-10 years) who underwent stress high-dose dipyridamole echocardiography and had angiographically non-significant (<50% visually assessed) stenosis in any major vessel and preserved left ventricular function. All patients were followed up for a median of 7.1 years (first quartile 5 and third quartile 10.5). Dipyridamole echocardiography test (DET) positivity for regional dysfunction occurred in 43(9%) patients. Kaplan-Meier survival estimates showed a significant better outcome for those patients with negative dipyridamole echocardiography test compared with those with a positive test (90 vs. 75.7%, at 140 months of follow-up, P=0.0018). At multivariable analysis, mild or moderate irregularity on coronary arteriogram (HR=3.3, CI 95%=1.7-6.2), diabetes (HR=3.5, CI 95%=1.4-9.2), and wall motion score index at peak stress (HR=6.7, CI 95%=2.5-17.8) were independent predictors of all-cause death.

CONCLUSION

DET adds incremental value to the prognostic stratification achieved with clinical and angiographic data in the subset of patients with normal or near-normal coronary arteries.

Proportion of oxidized LDL relative to plasma apolipoprotein B does not change during statin therapy in patients with heterozygous familial hypercholesterolemia

OBJECTIVE

Circulating oxidized low-density lipoprotein (LDL) has been shown to be a useful marker for identifying patients with coronary heart disease (CHD) and persons at high cardiovascular risk. The effect of cholesterol-lowering therapy on plasma level of oxidized LDL is not clear.

METHODS AND RESULTS

We investigated effects of cholesterol lowering by therapeutic intervention (2 years) with atorvastatin (80 mg daily) and simvastatin (40 mg daily) on circulating oxidized LDL (absolute level and in proportion to plasma apolipoprotein B) in relation to atherosclerosis progression (carotid intima-media thickness, carotid IMT) and to inflammation (high-sensitivity C-reactive protein, hsCRP) in 115 stable patients with heterozygous familial hypercholesterolemia (FH). Atorvastatin and simvastatin reduced plasma-oxidized LDL (-43 and -35%, respectively) in proportion to the decrease in plasma apolipoprotein B. Neither absolute nor relative level of oxidized LDL correlated with carotid IMT or hsCRP at baseline. Also changes in levels of circulating oxidized LDL were not related to changes in carotid IMT and hsCRP.

CONCLUSIONS

In familial hypercholesterolemia-oxidized LDL carried in plasma is strongly associated with apolipoprotein B but not with inflammation nor with carotid IMT, and statin treatment does not reduce oxidized LDL relative to apolipoprotein B.

Endothelial dysfunction: its role in hypertensive coronary disease

PURPOSE OF REVIEW

Coronary artery disease is the major cause of death worldwide. Hypertension is a major risk factor for developing coronary disease. It is now recognized that endothelial dysfunction is an early marker of coronary artery disease before structural changes to the vessel wall are apparent on angiography or intravascular ultrasound and that it has a prognostic value in predicting cardiovascular events in hypertensive patients. This review addresses recent developments in hypertension-induced endothelial dysfunction.

RECENT FINDINGS

Hyperaldosteronism causes endothelial dysfunction independent of high blood pressure. Exaggerated exercise blood pressure response has been related to endothelial dysfunction. Cyclosporin-A-induced endothelial dysfunction is related to reduced cholesterol content in caveolae. Chronic kidney disease induces changes in caveoli-1 and thus contributes to the reduced nitric oxide bioavailability, and causes oxidative stress independent of the high blood pressure. Asymmetric dimethylarginine plays a role in endothelial dysfunction in hypertensive patients independent of insulin resistance. 20-Hydroxyeicosatetraenoic acid is an independent predictor of hypertension in postmenopausal women. Endothelial dysfunction precedes and predicts the development of hypertension in postmenopausal women. Oral treatment with L-arginine improves endothelial dysfunction in hypertensives and lowers the blood pressure.

SUMMARY

The pathophysiology of endothelial dysfunction in hypertension is multifactorial. Recent findings have contributed to our understanding of mechanisms of endothelial dysfunction and support a role for early intervention to prevent irreversible vascular and organ damage.

Cardiovascular disease in women: Sex differences in presentation, risk factors, and evaluation

Cardiovascular disease (CVD) is the leading cause of mortality in women. Pathophysiology, risk factors, clinical presentation, and outcomes of coronary artery disease (CAD) differ in women, and a better understanding of the sex differences in these factors will potentially lead to a slowing of this epidemic in women. Often forgotten, women have higher complication rates post revascularization and higher in-hospital mortality post myocardial infarction compared with men despite a smaller burden of disease in women. Though overall women share the same risk factors as men in the development of CAD, certain risk factors appear to be particularly ominous, such as the presence of diabetes mellitus, low values of high-density lipoprotein cholesterol, high triglycerides, and psychologic depression. Disease detection in advanced CAD is more accurate with stress echocardiography (ECG) and perfusion single-photon emission computed tomography imaging in women than with stress ECG. Subclincial atherosclerotic disease detection with carotid artery intima media thickness assessment provides an opportunity to target preventive measures in women. This article focuses on some of the sex-specific differences.

Abnormal cortical pain processing in patients with cardiac syndrome X

AIMS

Previous studies suggested that an enhanced pain sensitivity is present in patients with cardiac syndrome X (SX). We investigated whether SX patients present abnormalities in the electrical cerebral signals generated by pain stimuli.

METHODS AND RESULTS

Cortical laser evoked potentials (LEPs) were recorded in 16 SX patients, in 10 patients with refractory angina due to obstructive coronary artery disease (CAD) and in 13 healthy controls. LEPs were recorded during stimulation of chest and right hand dorsum. Three sequences of painful stimuli were applied at each site. Subjective pain rating was assessed by a 0-100 mm visual analogic scale (VAS). Basal LEPs did not differ among groups and there were no differences for most LEP components across the repetitions of stimuli. However, the amplitude of the N2/P2 LEP component, specifically reflecting cortical pain processing, decreased across the three sequences of stimuli in controls and CAD patients, but not in SX patients. Compared with the first sequence, the N2/P2 amplitude during the third sequence of stimuli in the three groups was 77+/-16, 56+/-24, and 99+/-34%, respectively, for chest (P=0.001), and 63+/-31, 72+/-17, and 98+/-46%, respectively, for right hand (P=0.03) stimulation. The changes in VAS pain score across the three sequences paralleled those of N2/P2 amplitude.

CONCLUSION

Our data show that in SX patients, central handling of painful stimuli is characterized by inadequate habituation, which might play a role in determining the peculiar clinical characteristics of anginal chest pain of these patients.

The effects of anaemia as a programming agent in the fetal heart

The intrauterine environment plays a powerful role in determining the life-long risk of cardiovascular disease. A number of stressors are well known to affect the development of the cardiovascular system in utero including over/under maternal nutrition, excess glucocorticoid and chronic hypoxia. Chronic fetal anaemia in sheep is a complex stressor that alters cardiac loading conditions, causes hypoxic stress and stimulates large changes in flow to specific tissues, including large increases in resting coronary blood flow and conductance. Decreased viscosity can account for approximately half of the increased flow. It appears that immature hearts are 'plastic' in that increases in coronary conductance with fetal anaemia persist into adulthood even if the anaemia is corrected before birth. These large changes in conductance are possible only through extensive remodelling of the coronary tree. Adult hearts that were once anaemic in utero are more resistant to hypoxic stress as adults but it is not known whether such an adaptation would be deleterious in later life. These studies indicate the need for investigation into the basic mechanisms of coronary tree remodelling in the immature myocardium. New information on these mechanisms is likely to lead to better prevention of and therapies for adult-onset coronary disease.

Role of noninvasive testing in the clinical evaluation of women with suspected coronary artery disease: Consensus statement from the Cardiac Imaging Committee, Council on Clinical Cardiology, and the Cardiovascular Imaging and Intervention Committee, Council on Cardiovascular Radiology and Intervention, American Heart Association

Cardiovascular disease is the leading cause of mortality for women in the United States. Coronary heart disease, which includes coronary atherosclerotic disease, myocardial infarction, acute coronary syndromes, and angina, is the largest subset of this mortality, with >240,000 women dying annually from the disease. Atherosclerotic coronary artery disease (CAD) is the focus of this consensus statement. Research continues to report underrecognition and underdiagnosis of CAD as contributory to high mortality rates in women. Timely and accurate diagnosis can significantly reduce CAD mortality for women; indeed, once the diagnosis is made, it does appear that current treatments are equally effective at reducing risk in both women and men. As such, noninvasive diagnostic and prognostic testing offers the potential to identify women at increased CAD risk as the basis for instituting preventive and therapeutic interventions. Nevertheless, the recent evidence-based practice program report from the Agency for Healthcare Research and Quality noted the paucity of women enrolled in diagnostic research studies. Consequently, much of the evidence supporting contemporary recommendations for noninvasive diagnostic studies in women is extrapolated from studies conducted predominantly in cohorts of middle-aged men. The majority of diagnostic and prognostic evidence in cardiac imaging in women and men has been derived from observational registries and referral populations that are affected by selection and other biases. Thus, a better understanding of the potential impact of sex differences on noninvasive cardiac testing in women may greatly improve clinical decision making. This consensus statement provides a synopsis of available evidence on the role of the exercise ECG and cardiac imaging modalities, both those in common use as well as developing technologies that may add clinical value to the diagnosis and risk assessment of the symptomatic and asymptomatic woman with suspected CAD.

Cardiovascular risk factors and endothelial dysfunction

Endothelial dysfunction is a feature of atherosclerosis and is associated with CHD (coronary heart disease) risk factors. This study aimed to determine the relationship between the degree of endothelial dysfunction and calculated cardiovascular risk. Endothelial function, as determined by the ACh/NP (acetycholine/sodium nitroprusside response) ratio on brachial plethysmography, was compared with cardiovascular risk as calculated from the Framingham, PROCAM (Prospective Cardiovascular Munster) and MRFIT (Multiple Risk Factor Intervention Trial) algorithms in 246 (187 male) patients, including 44 (22%) with established CHD. Endothelial dysfunction correlated with the total number of risk factors (r2=0.22; P=0.002) and was related to LDL (low-density lipoprotein)-cholesterol in men and triacylglycerols (triglycerides) in women. The ACh/NP ratio correlated with the occurrence of diabetes, CHD and the LDL-cholesterol concentration (r2=0.58; P<0.001). Endothelial dysfunction was associated with presence of CHD on receiver-operating characteristic plot analysis (area=0.706+/-0.04; P=0.001). There was no correlation between ACh/NP ratio and CHD risk calculated with the Framingham algorithm in men, although both ACh and NP response correlated separately with risk in women. The endothelial ACh/NP ratio correlated with absolute risk in the PROCAM algorithm (r2=0.41; P<0.005). Intermediate results were obtained with MRFIT. Individual risk factors make different contributions to endothelial dysfunction compared with their role in risk calculators. The stronger relationship of endothelial dysfunction with PROCAM risk reflects the contribution of male sex, LDL-cholesterol and triacylglycerols to risk calculated by this algorithm.

Nitric oxide, angiotensin II, and reactive oxygen species in hypertension and atherogenesis

A balance among nitric oxide (NO), angiotensin II (Ang II), and reactive oxygen species (ROS) in the endothelium is necessary for maintaining the homeostasis of the vascular wall. Oxidative stress has been shown to play a critical role in the development of hypertension and atherosclerosis. Although there is overwhelming evidence that hypertension promotes atherosclerosis, the relative contribution and/or interaction of hemodynamic and oxidative stress remains undefined. NO is synthesized in the endothelium by NO synthase and antagonizes the vasoconstrictive and proatherosclerotic effects of Ang II. On the other hand, Ang II decreases NO bioavailability by promoting oxidative stress. A better understanding of the pathophysiologic mechanisms involved in the link between hypertension and atherosclerosis may aid in developing therapeutic interventions. We propose that those antihypertensive agents that lower blood pressure and concomitantly restore the homeostatic balance of vasoactive agents in the endothelium would be more effective in preventing or arresting atherosclerosis.