The pathogenesis of coronary artery disease and the acute coronary syndromes (2)

The relationship between serum levels of Zn and Cu and severity of coronary atherosclerosis

The essential trace elements play important roles in the maintainance of the normal structure and physiology of cells. Several research groups have demonstrated that they also play important roles in states of cardiovascular diseases. Our aim is to investigate whether there is a relationship between trace elements (Zn and Cu) and the degree of atherosclerosis. The sample consisted of 67 patients with coronary artery disease and 26 clinically healthy individuals. Ninety-three subjects were separated into four groups according to their Gensini scores, the number of diseased vessels, the presence of acute coronary syndrome, and ejection fraction. Each group was divided into three subgroups, and serum zinc and copper levels were measured for each individual. The serum levels of zinc and copper were found to be significantly lower in patients with atherosclerosis than in the control group, but there were no significant differences in the serum levels of Cu and Zn between severe atherosclerosis and mild atherosclerosis. In Spearman's rank correlation, the zinc and copper levels were correlated with the Gensini score and the number of diseased vessels. The present study revealed a relationship between the serum levels of zinc and copper and atherosclerosis, but not between these levels and the severity of the disease.

The management of thrombotic lesions in the cardiac catheterization laboratory

Plaque rupture with superimposed thrombosis is the major mechanism of acute coronary syndromes. Although angiography underestimates the presence of thrombi, their detection is a poor prognostic indicator which is proportional to their size. Although emergent percutaneous coronary intervention (PCI) in the setting of ST elevation myocardial infarction (STEMI) and early PCI in the setting of unstable angina and non-STEMI were shown to be preferred strategies, the presence of angiographic thrombosis by virtue of causing micro and macro embolization can reduce the benefit of the intervention. Antiplatelet therapy especially using glycoprotein IIb/IIIa inhibitors reduces thrombus size, and improves myocardial perfusion and ventricular function. Routine manual aspiration prior to PCI in STEMI also improves myocardial flow and reduces distal embolization and improves survival. Distal embolic protection devices and mechanical thrombectomy do not have the same clinical benefits however, rheolytic thrombectomy may have a role in large vessels with a large thrombi.

Genetic testing for early detection of individuals at risk of coronary heart disease and monitoring response to therapy: challenges and promises

Coronary heart disease (CHD) often presents suddenly with little warning. Traditional risk factors are inadequate to identify the asymptomatic high-risk individuals. Early identification of patients with subclinical coronary artery disease using noninvasive imaging modalities would allow the early adoption of aggressive preventative interventions. Currently, it is impractical to screen the entire population with noninvasive coronary imaging tools. The use of relatively simple and inexpensive genetic markers of increased CHD risk can identify a population subgroup in which benefit of atherosclerotic imaging modalities would be increased despite nominal cost and radiation exposure. Additionally, genetic markers are fixed and need only be measured once in a patient's lifetime, can help guide therapy selection, and may be of utility in family counseling.

Inflammation and the development of atherosclerosis

Atherosclerosis is a progressive disease causally associated with multiple cardiovascular risk factors, including dyslipidemia. Without effective intervention, atherosclerosis becomes evidenced clinically as coronary artery and cerebrovascular disease, both of which remain the leading causes of death worldwide. Multiple lines of investigation indicate a central role for inflammation in atherosclerotic plaque progression, vulnerability and thrombogenicity. Randomized clinical trials have documented the benefit of lipid-lowering therapy for both primary and secondary prevention of cardiovascular events. Statins, a class of drugs that lower cholesterol levels by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, have been shown to slow the progression of the atheroma and the frequency of associated clinical events to an extent that cannot be attributed solely to LDL reduction. The non-LDL or pleiotropic effects of statins are attributed to anti-inflammatory activity, enhanced endothelial function, and inhibition of oxidative stress. In this review, we discuss the role of inflammation in atherogenesis along with the effects of statins in slowing this process through LDL-dependent and -independent mechanisms.

Intravascular ultrasound assessment of the association between spatial orientation of ruptured coronary plaques and remodeling morphology of culprit plaques in ST-elevation acute myocardial infarction

The aim of this study was to assess the association between the spatial location of plaque rupture and remodeling pattern of culprit lesions in acute anterior myocardial infarction (MI). Positive remodeling suggests a potential surrogate marker of plaque vulnerability, whereas plaque rupture causes thrombus formation followed by coronary occlusion and MI. Intravascular ultrasound (IVUS) can determine the precise spatial orientation of coronary plaque formation. We studied 52 consecutive patients with acute anterior MI caused by plaque rupture of the culprit lesion as assessed by preintervention IVUS. The plaques were divided into those with and without positive remodeling. We divided the plaques into three categories according to the spatial orientation of plaque rupture site: myocardial (inner curve), epicardial (outer curve), and lateral quadrants (2 intermediate quadrants). Among 52 plaque ruptures in 52 lesions, 27 ruptures were oriented toward the epicardial side (52%), 18 toward the myocardial side (35%), and 7 in the 2 lateral quadrants (13%). Among 35 plaques with positive remodeling, plaque rupture was observed in 21 (52%) on the epicardial side, 12 (34%) on the myocardial side, and 2 (6%) on the lateral side. However, among 17 plaques without positive remodeling, plaque rupture was observed in 6 (35%), 6 (35%), and 5 (30%), respectively (p = 0.047). Atherosclerotic plaques with positive remodeling showed more frequent plaque rupture on the epicardial side of the coronary vessel wall in anterior MI than those without positive remodeling.

Hypercoagulability biomarkers in Trypanosoma cruzi -infected patients

There is a current controversy over the hypothesis that a number of thromboembolic events could be related to hypercoagulable state in patients with chronic Chagas disease. This study was designed to determine whether a prothrombotic state existed in chronic Trypanosoma cruzi-infected patients and, if so, to describe its evolution after treatment with Benznidazole. Twenty-five patients with chronic Chagas disease and 18 controls were evaluated. The markers used were prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, plasminogen, protein C, total protein S, free protein S, factor VIII, D-dimer, activated factor VIIa, tissue-type plasminogen activator inhibitor-1, prothrombin fragment 1+2 (F₁+₂), plasmin-antiplasmin complexes, soluble P-selectin and endogenous thrombin potential (ETP). Despite statistically significant differences between cases and controls in several markers, only ETP (which quantifies the ability of plasma to generate thrombin when activated through tissue factor addition) (p<0.0001) and F₁+₂ (a marker of thrombin generation in vivo) (p<0.0001) showed values outside the normal levels in patients compared with controls. Similar results were obtained in these markers six months after treatment in the cohort of cases (p<0.0008 and p<0.004, respectively). These results may be relevant in clinical practice. Though current treatment for Chagas disease is still controversial, if it were considered as a thromboembolic risk factor the antiparasitic treatment strategy could be reinforced. The results also support further research on haemostasis parameters as candidates for early surrogate biomarkers of cure or progression of Chagas disease.

The impact of plaque characterization assessed by intravascular ultrasound on myocardial perfusion after primary angioplasty in patients With ST-segment elevation myocardial infarction

BACKGROUND

Previous studies described that inadequate tissue perfusion after primary angioplasty in ST-elevation myocardial infarction (STEMI) patients is associated with adverse cardiac events. This study evaluated whether plaque morphological intravascular ultrasound (IVUS) characteristics affects tissue perfusion after stent implantation in STEMI patients.

METHODS AND RESULTS

A total of consecutive 306 STEMI patients who underwent primary angioplasty with IVUS were analyzed. Maximum ST-segment elevation before angioplasty was compared with ST-segment levels 60min after angioplasty. Percent ST-segment resolution (STR) was calculated and categorized as complete (>70%), partial (30-70%), and absent (<30%). Qualitative and quantitative IVUS analyses were performed using standard methods. Plaque with ultrasound attenuation was defined as IVUS finding with backward signal attenuation behind plaque >180° without dense calcium. One-hundred-fifty patients had complete, 101 had partial, and 55 had absent STR. The incidence of in-hospital death tended to be higher in absent STR than in partial and complete STR groups. Multivariate analysis indicated that remodeling index (P=0.004), the presence of ultrasound attenuation (P=0.02), percentage stent expansion (P=0.03), and the presence of deep calcium (P=0.049) were the independent predictors related to the occurrence of absent STR after angioplasty.

CONCLUSIONS

Positive vessel remodeling, plaque with ultrasound attenuation >180°, deep calcium, and stent overexpansion as assessed by IVUS are associated with the absence of STR after primary angioplasty in patients with STEMI.

A few immobilized thrombins are sufficient for platelet spreading

Eukaryotic cells respond to signaling molecules with picomolar to nanomolar sensitivities. However, molar concentrations give no suggestion of the sufficient number of molecules per cell and are confusing when referring to physiological situations in which signaling molecules act in an immobilized state. Here, we studied platelet adhesion by thrombin, a key step in normal hemostasis and pathological arterial thrombosis. We generated a biofunctional nanosheet surface to mimic the in vivo solid-state interaction between platelets and thrombin at sites of injured tissues. We observed that <10 molecules readily activate platelets with high specificity, resulting in platelet adhesion and spreading. This number is much lower than expected from previous experiments in solution, in which the sole activation of platelets required a >1000-fold stoichiometric excess of thrombin. We conclude that immobilizing thrombin apposed to the membrane receptor allows platelets to respond with very high sensitivity. Moreover, we propose that irreversible cell activation may require several ligands to avoid activation by single, mislocalized signaling molecules.

Cardiovascular risk in obesity: different activation of inflammation and immune system between obese and morbidly obese subjects

BACKGROUND

Both inflammation and immunity are involved in the development and progression of atherosclerosis. Obesity is considered a major modifiable cardiovascular risk factor, however, the correlation between increasing degrees of obesity and cardiovascular risk is not clear yet. Aim of our study was to investigate how different degrees of obesity are associated with inflammation and immune system responses.

METHODS

One-hundred healthy individuals were divided into 3 groups according to body mass index (BMI): 22 overweight (OW), 26 obese (O) and 52 morbidly obese (MO). High-sensitivity C-Reactive Protein (hs-CRP, immunonephelometry), leptin (radio-immunoassay) and CD4+CD28nullT-lymphocytes (flow-cytometry), a particular subset of T-lymphocytes with pro-atherogenic and plaque-destabilizing properties, were assessed.

RESULTS

hs-CRP levels were significantly higher in O vs OW (p=0.036), in MO vs OW (p<0.001) and in MO vs O (p=0.012). Similarly, leptin levels were higher in O vs OW (p=0.02), in MO vs OW (p<0.001) and in MO vs O (p<0.001). CD4+CD28nullT-lymphocytes were higher in O vs OW (p<0.001), in O vs MO (p=0.03) and in MO vs OW (p=0.01). hs-CRP and leptin levels significantly correlated each other (r=0.39; p<0.001) and with waist circumference (r=0.52; p<0.001; r=0.64; p<0.001) and BMI (r=0.60; p<0.001; r=0.74; p<0.001).

CONCLUSIONS

Our study demonstrates that, notwithstanding higher levels of inflammation, MO are characterized by less detrimental immune activation, as shown by the reduced CD4+CD28nullT-cells expansion as compared to OW and O, which might translate in less immune vascular injury. These findings suggest that MO might represent a particular population, in which different pathophysiological mechanisms take part if compared with "classic" obesity.

Dietary α-Linolenic Acid Inhibits Arterial Thrombus Formation, Tissue Factor Expression, and Platelet Activation

Objective—

Plant-derived α-linolenic acid (ALA) may constitute an attractive cardioprotective alternative to fish-derived n -3 fatty acids. However, the effect of dietary ALA on arterial thrombus formation remains unknown.

Methods and Results—

Male C57Bl/6 mice were fed a high-ALA or low-ALA diet for 2 weeks. Arterial thrombus formation was delayed in mice fed a high-ALA diet compared with those on a low-ALA diet (n=7; P <0.005). Dietary ALA impaired platelet aggregation to collagen and thrombin (n=5; P <0.005) and decreased p38 mitogen-activated protein kinase activation in platelets. Dietary ALA impaired arterial tissue factor (TF) expression, TF activity, and nuclear factor-κB activity (n=7; P <0.05); plasma clotting times and plasma thrombin generation did not differ (n=5; P =not significant). In cultured human vascular smooth muscle and endothelial cells, ALA inhibited TF expression and activity (n=4; P <0.01). Inhibition of TF expression occurred at the transcriptional level via the mitogen-activated protein kinase p38 in smooth muscle cells and p38, extracellular signal-regulated kinases 1 and 2, and c-Jun N-terminal kinases 1 and 2 in endothelial cells.

Conclusion—

ALA impairs arterial thrombus formation, TF expression, and platelet activation and thereby represents an attractive nutritional intervention with direct dual antithrombotic effects.

Non-invasive detection of vulnerable coronary plaque

Critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes and sudden cardiac death. Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis. Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease. Recent advances in invasive and non-invasive imaging techniques have shown the potential to identify these high-risk plaques. Non-invasive imaging with magnetic resonance imaging, computed tomography and positron emission tomography holds the potential to differentiate between low- and high-risk plaques. There have been significant technological advances in non-invasive imaging modalities, and the aim is to achieve a diagnostic sensitivity for these technologies similar to that of the invasive modalities. Molecular imaging with the use of novel targeted nanoparticles may help in detecting high-risk plaques that will ultimately cause acute myocardial infarction. Moreover, nanoparticle-based imaging may even provide non-invasive treatments for these plaques. However, at present none of these imaging modalities are able to detect vulnerable plaque nor have they been shown to definitively predict outcome. Further trials are needed to provide more information regarding the natural history of high-risk but non-flow-limiting plaque to establish patient specific targeted therapy and to refine plaque stabilizing strategies in the future.

Vascular targeting of antithrombotic agents

In this review we discuss the limited efficacy for current pharmacological agents used in prophylaxis and treatment of thrombosis and highlight targeted delivery of anti-thrombotic agents to fibrin, platelets, red blood cells and endothelium.

Exposure to smoking cues: cardiovascular and autonomic effects

Laboratory exposures to smoking cues have been shown to reliably induce self-reported cigarette cravings among smokers, a model of environmentally triggered urges to smoke that can contribute to poorer cessation success. Several studies have also demonstrated that cue exposures give rise to changes in heart rate and blood pressure. Few studies, however, have investigated possible cue effects on heart rate and blood pressure variability (HRV and BPV). Particularly intriguing in this regard are cardiac oscillations in the low (i.e., 0.04-0.15 Hz), and high (i.e., 0.15-0.50 Hz) frequency range, which are thought to reflect components of autonomic control and response to environmental challenges. A closer examination of cardiovascular reactivity may thus help characterize the autonomic response to smoking cue exposure. To that end, an experimental study was conducted in which nicotine dependent daily smokers (n=98) were exposed to guided imagery of neutral and smoking situations, while continuous, noninvasive, beat-to-beat cardiovascular data were collected. Consistent with previous research, the findings revealed significant increases in both systolic and diastolic blood pressure during smoking imagery, relative to neutral imagery. In addition, power spectral density analyses of heart rate and blood pressure variability revealed elevated HRV and BPV in both the low- and high-frequency ranges during the smoking imagery. The results suggest the presence of an autonomic component to smoking cue reactivity, and also raise the possibility of long-term negative cardiac consequences for smokers who ubiquitously encounter cues in their daily environments.

Decreased circulating endothelial progenitor cell levels and function in essential hypertensive patients with electrocardiographic left ventricular hypertrophy

The aim of this study was to explore the role of circulating endothelial progenitor cells (EPCs) and endothelial apoptotic microparticles in hypertensive patients with and without electrocardiographic left ventricular hypertrophy (LVH). Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC level by quantification of circulating EPC markers (defined as CD34(+)CD133(+), CD34(+)KDR(+)) and endothelial apoptotic microparticles (defined as CD31(+)/annexin V(+)) in peripheral blood samples. The LVH was defined by ECG with the Cornell voltage criteria. In total, 128 hypertensive patients (83 men and 45 women, aged 59±14 years) were enrolled in this study, in which 107 patients (84%) showed no electrocardiographic evidence of LVH, and 21 patients (16%) fulfilled the LVH criteria by ECG. There were no significant differences in basic characteristics between the two groups, but hypertensive patients with LVH had a higher urine albumin excretion rate than those without LVH (P=0.027). Furthermore, hypertensive patients with LVH were shown to have decreased circulating EPC numbers (all P<0.05) and adhesive function compared with those without LVH (LVH vs. no LVH: 14±6 vs. 30±6 cells per high-power field, P<0.001). Increased numbers of endothelial apoptotic microparticles were noted in hypertensive patients with LVH (4.2±4.9 vs. 2.4±3.4%, P=0.115), although the difference was not significant. This study showed that essential hypertensive patients with electrocardiographic LVH evidence have decreased circulating EPC numbers and adhesive function compared with those without LVH. These findings may explain the pathogenetic processes that link hypertensive LVH and endothelial injury in cardiovascular disease.

Angioscopic and virtual histology intravascular ultrasound characteristics of culprit lesion morphology underlying coronary artery thrombosis

Although rupture of vulnerable plaque with subsequent thrombosis is the most common mechanism of acute coronary syndromes, a significant percentage of patients with acute coronary syndrome may not have plaque rupture. We used angioscopy and virtual histology intravascular ultrasound (VH-IVUS) to investigate the underlying morphology of coronary thrombosis. We correlated the angioscopic diagnosis of coronary thrombosis in 42 lesions (37 patients) with gray-scale and VH-IVUS findings of the underlying plaque. By angioscopy plaque rupture was present in 19 thrombotic lesions (45.2%), whereas 23 (54.8%) had no rupture. VH-IVUS findings comparing thrombotic lesions with to those without angioscopic plaque rupture were remarkably similar except that angioscopic nonruptures tended to have more necrotic core (NC) at the minimum lumen area site (22.2 ± 12.5% vs 16.3 ± 9.3%, p=0.09) and at the maximum NC site (32.7 ± 12.8% vs 25.0 ± 12.1%, p=0.053) compared to angioscopic ruptures. Furthermore, among 19 lesions with angioscopic plaque rupture, there were 11 VH thin-cap fibroatheromas (TCFAs; 57.9%); among 23 lesions without angioscopic rupture, there were 17 VH-TCFAs (73.9%, p=0.22). In conclusion, the similarity of VH-IVUS plaque composition (percentage of NC and percentage of VH-TCFA) in lesions with or without angioscopic plaque rupture suggest a spectrum of underlying morphologies to explain thrombosis in the absence of a ruptured plaque including classic erosions, small (and undetectable) plaque ruptures, and potentially unruptured TCFAs with superimposed thrombosis.

Anticoagulation in the management of non-ST-segment elevation acute coronary syndrome

There are currently over 1 million patients admitted to hospitals in the United States with the diagnosis of non-ST-segment elevation acute coronary syndrome (NSTE ACS). Due to the significant morbidity and mortality associated with NSTE ACS, appropriate use of the numerous medications employed is critical in ensuring optimal outcomes. Because atherosclerotic plaque rupture and thrombus formation are the central pathophysiologic process in patients with NSTE ACS, it is important to utilize effective and safe combinations of antiplatelet and anticoagulant drug therapy. There are a number of different anticoagulant agents available for use in patients with NSTE ACS, but it is essential to have an in-depth knowledge of the setting in which these agents have been investigated, what current consensus guidelines recommend, as well as an appreciation for the treatment approach and philosophy of the institution for management of patients with NSTE ACS. In this review manuscript, the reader will find an evaluation of the current guidelines concerning the use of anticoagulant therapy in patients with NSTE ACS, as well as a detailed examination of the literature with critical analysis on issues that should be considered when deciding on the appropriate implementation of anticoagulant therapy in protocols for NSTE ACS patients.

Anticoagulation in the management of ST-segment elevation myocardial infarction

Patients with ST-segment elevation myocardial infarction (STEMI) require immediate reperfusion therapy in order to salvage ischemic myocardial tissue and reduce mortality. Reperfusion therapy can be provided mechanically with primary percutaneous coronary intervention (PCI), or pharmacologically with fibrinolysis. Regardless of the reperfusion strategy selected, the appropriate use of anticoagulant therapy is critical to its success. There have been a number of clinical trials evaluating the different anticoagulants in patients with STEMI, as well as recent updates to the guidelines for management of patients with STEMI and on the use of PCI. When making clinical decisions on the use of anticoagulant therapy in the management of patients with STEMI, it is important to not only understand the contents of these consensus guidelines but to also have an appreciation of the details of the clinical trials that have evaluated the different anticoagulants. In this review, the reader will find an evaluation of the current guidelines concerning the use of anticoagulant therapy in patients with STEMI as well as a detailed examination of the literature with critical analysis on issues that should be considered when deciding on the appropriate implementation of anticoagulant therapy in patients with STEMI undergoing either mechanical or pharmacologic reperfusion.

Update on lipids, inflammation and atherothrombosis

Atherosclerosis is an inflammatory disease that involves the arterial wall and is characterised by the progressive accumulation of lipids in the vessel wall. The first step is the internalisation of lipids (LDL) in the intima with endothelial activation which enhances the permeability of the endothelial layer and the expression of cytokines/chemokines and adhesion molecules. These events increase LDL particles accumulation in the extracellular matrix where they aggregate/fuse, are retained by proteoglycans and become targets for oxidative and enzymatic modifications. In turn, retained pro-atherogenic LDLs enhance selective leukocyte recruitment and attachment to the endothelial layer inducing their transmigration across the endothelium into the intima. While smooth muscle cell numbers decline with the severity of plaque progression, monocytes differentiate into macrophages, a process associated with the upregulation of pattern recognition receptors including scavenger receptors and Toll-like receptors leading to foam cell formation. Foam cells release growth factors, cytokines, metalloproteinases and reactive oxygen species all of which perpetuate and amplify the vascular remodelling process. In addition, macrophages release tissue factor that, upon plaque rupture, contributes to thrombus formation. Smooth muscle cells exposed in eroded lesions are also able to internalise LDL through LRP-1 receptors acquiring a pro-thrombotic phenotype and releasing tissue factor. Platelets recognise ligands in the ruptured or eroded atherosclerotic plaque, initiate platelet activation and aggregation leading to thrombosis and to the clinical manifestation of the atherothrombotic disease. Additionally, platelets contribute to the local inflammatory response and may also participate in progenitor cell recruitment.

Insulin resistance is associated with the metabolic syndrome and is not directly linked to coronary artery disease

BACKGROUND

Insulin resistance (IR) is the key feature of the metabolic syndrome (MetS). Its association with directly visualized coronary atherosclerosis is unclear. We hypothesised that insulin resistance is associated with both angiographically determined coronary artery disease (CAD) and with the MetS.

METHODS

In 986 consecutive patients undergoing coronary angiography for the evaluation CAD, IR was determined by the HOMA index; the MetS was defined according to NCEP-ATPIII criteria; and significant CAD was diagnosed when coronary stenoses ≥50% were present.

RESULTS

HOMA IR scores were higher in MetS patients than in subjects without the MetS (4.9±6.4 vs. 2.2±2.0; p<0.001). HOMA IR did not differ significantly between patients with significant CAD and those who did not have significant CAD. When both, the presence of MetS and of significant CAD were considered, HOMA IR was significantly higher in patients with the MetS both among those who had significant CAD (4.9±6.8 vs. 2.2±1.8; p<0.001) and among those who did not have significant CAD (5.0±5.8 vs. 2.1±2.3; p<0.001), it did not differ significantly between patients with significant CAD and subjects without significant CAD among patients with the MetS nor among those without MetS. Similar results were obtained with the IDF definition of the MetS.

CONCLUSION

IR is significantly associated with the MetS but not with angiographically determined CAD. IR may play a greater role in the eventual precipitation of thrombosis than in the gradual progression of atherosclerosis.

Adenosine and blood platelets

Adenosine is an important regulatory metabolite and an inhibitor of platelet activation. Adenosine released from different cells or generated through the activity of cell-surface ectoenzymes exerts its effects through the binding of four different G-protein-coupled adenosine receptors. In platelets, binding of A(2) subtypes (A(2A) or A(2B)) leads to consequent elevation of intracellular cyclic adenosine monophosphate, an inhibitor of platelet activation. The significance of this ligand and its receptors for platelet activation is addressed in this review, including how adenosine metabolism and its A(2) subtype receptors impact the expression and activity of adenosine diphosphate receptors. The expression of A(2) adenosine receptors is induced by conditions such as oxidative stress, a hallmark of aging. The effect of adenosine receptors on platelet activation during aging is also discussed, as well as potential therapeutic applications.

Curcumin inhibits GPVI-mediated platelet activation by interfering with the kinase activity of Syk and the subsequent activation of PLCgamma2

Turmeric (Curcuma longa), a herbal remedy and culinary spice, has been used in traditional Indian culture for millennia. An active ingredient found in turmeric is curcumin (diferuloylmethane). In the current study, we investigated the antiplatelet properties of this naturally occurring compound. Curcumin inhibited human platelet aggregation and dense granule secretion induced by GPVI agonist convulxin in a concentration-dependent manner. At 50 microM, it effectively inhibited the maximal extent of aggregation and dense granule secretion to as much as 75%. It also dramatically inhibited the activation-dependent tyrosine phosphorylation of Y753 and Y759 on PLCgamma2, but did not affect the phosphorylation of Y145 residue on the cytosolic adaptor protein SLP-76. Interestingly, curcumin had no significant effect on the phosphorylation of Y525/Y526 present on the activation loop of Syk (spleen tyrosine kinase), but had a significant inhibitory effect on in vitro Syk kinase activity. Moreover, the inhibitory action of curcumin is not due to an inhibition of thromboxane generation because all our studies were performed using aspirin-treated platelets. We conclude that curcumin inhibits platelet activation induced by GPVI agonists through interfering with the kinase activity of Syk and the subsequent activation of PLCgamma2.

Sex differences in hospital mortality following acute myocardial infarction in China: findings from a study of 45 852 patients in the COMMIT/CCS-2 study

OBJECTIVE

To assess the sex difference in hospital mortality following ST elevation myocardial infarction (STEMI) in China.

DESIGN

Observational study of patients enrolled into a large trial, adjusting for age, presenting characteristics and hospital treatments using logistic regression.

SETTINGS

1250 hospitals in China during 1999-2005.

PATIENTS

42 683 STEMI patients, including 31 309 men and 11 374 women.

INTERVENTION

In the original trial, all patients received 162 mg of aspirin plus 75 mg of clopidogrel daily or matching placebo and metoprolol (15 mg intravenous then 200 mg oral daily) or matching placebo. All other aspects of patients' treatments were at the discretion of responsible doctors.

MAJOR OUTCOMES

Hospital mortality from any cause during the scheduled trial treatment period (ie, up to 4 weeks in hospital).

RESULTS

Overall, 8% of the patients died in hospital, with the crude hospital mortality being twice as high in women as in men (12.6% vs 6.3%). After adjusting for age, the sex difference in hospital mortality attenuated but remained highly significant (OR 1.54; 95% CI 1.43 to 1.66). Further adjustment for other baseline characteristics and for the treatments given in hospital had little effect on the sex difference in hospital mortality (OR 1.50, 95% CI 1.38 to 1.62). The difference in hospital mortality was greater at a younger age, with the adjusted ORs being 2.14, 1.70, 1.48 and 1.18, respectively, for ages <55, 55-64, 65-74 and ≥75 years (p=0.0001 for trend).

CONCLUSION

Compared with men of the same age, women had approximately a 50% higher mortality following hospital admission for STEMI, with a particularly higher excess risk at age <55 years.

Impact of smoking on the outcome of patients treated with drug-eluting stents: 1-year results from the prospective multicentre German Drug-Eluting Stent Registry (DES.DE)

BACKGROUND

Cigarette smoking strongly increases morbidity and mortality from cardiovascular causes, but the relevance of smoking in patients treated with drug-eluting stents (DES) is unknown.

AIMS

To assess the impact of smoking on the presentation and outcome of patients treated with DES.

METHODS AND RESULTS

We analyzed data from the prospective multicentre German Drug-Eluting Stent Registry (DES.DE) and identified 1,122 patients who had never smoked and 1,052 patients who were current smokers. Smokers were younger (56.5 vs. 69.4 years, p < 0.0001), more often males, with less frequent diabetes and hypertension compared to non-smokers. Smokers presented more often with acute coronary syndromes. After a mean follow-up of 12.5 months, smokers had both higher mortality (4.6 vs. 2.7%, p < 0.05) and myocardial infarction (MI) rates (4.9 vs. 3%, p < 0.01). There was no significant difference between smokers and non-smokers in the rate of target vessel revascularization (9.8 vs. 11.4%, p = 0.26). Major adverse cardiac and cerebrovascular events (defined as the composite of death, MI and stroke, MACCE) were higher in smokers (10.6 vs. 6.1%, p < 0.001). Moreover, after adjustment for baseline clinical and angiographic variables, smoking continued to be a strong independent predictor for MACCE (OR = 2.34, 95% CI 1.49-3.68). In a subgroup analysis, we found that the increased risk of smoking was most prominent in patients presenting with stable angina pectoris (OR = 3.71, 95% CI 1.24-2.57, p < 0.05). Smoking almost doubled the risk for MACCE in acute MI patients, though this did not reach statistical significance (adjusted OR = 1.91, 95% CI 0.93-3.94, p = 0.74).

CONCLUSION

This large multicentre DES registry provides evidence that smokers treated with DES, despite lower incidence of predisposing risk factors for atherosclerosis, experience higher rates of death and MI compared to non-smokers, particularly in the setting of stable coronary artery disease. Smoking has only marginal effects on target vessel revascularization rates in patients treated with DES.

Increased circulating CD31+/annexin V+ apoptotic microparticles and decreased circulating endothelial progenitor cell levels in hypertensive patients with microalbuminuria

OBJECTIVE

Microalbuminuria is associated with an increased risk for all-cause and cardiovascular mortality, but the pathophysiologic mechanism underlying the association between urinary albumin excretion and cardiovascular disease remains unclear. Here, we tested the hypothesis that enhanced endothelial apoptotic microparticles and decreased endothelial progenitor cell (EPC) levels might contribute to the pathophysiology of microalbuminuria or macroalbuminuria in cardiovascular disease.

METHODS

Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC levels by quantification of circulating CD31/annexin V apoptotic microparticles and EPC markers (defined as KDRCD133, CD34CD133, CD34KDR) in peripheral blood.

RESULTS

In total, 125 patients with hypertension were enrolled in the study, of whom 80 patients (64%) were with normoalbuminuria (albumin excretion rate of <20 microg/min, overnight urine samples), 35 patients (28%) with microalbuminuria (an albumin excretion rate of 20-200 microg/min), and 10 patients (8%) with macroalbuminuria (an albumin excretion rate >200 microg/min). Compared to hypertensive patients with normoalbuminuria, patients with microalbuminuria or macroalbuminuria had significantly more diabetes (P = 0.005), higher systolic blood pressure (P = 0.018), and elevated serum creatinine levels (P < 0.001). Among the three groups, patients with microalbuminuria or macroalbuminuria had significantly increased CD31/annexin V apoptotic microparticles (1.8 +/- 2.2 versus 3.0 +/- 4.3 versus 5.2 +/- 6.2%, P = 0.044) and decreased circulating EPC numbers (P < 0.05). By multivariate analysis, CD31/annexin V apoptotic microparticle level was an independent predictor of urinary albumin excretion rate in hypertensive patients (P < 0.001). Microparticles isolated from hypertensive patients with microalbuminuria or macroalbuminuria attenuated EPC proliferation, migration, and increased H2O2 production, cellular senescence and apoptosis in comparison with those from hypertensive patients with normoalbuminuria.

CONCLUSION

These findings suggest that hypertensive patients with microalbuminuria or macroalbuminuria have increased endothelial apoptotic microparticles and decreased circulating EPC levels, which may contribute to atherosclerotic disease progression and enhanced cardiovascular risk in hypertensive patients with nephropathy.

[Vein thromboembolism prevention in stroke patients]

INTRODUCTION

Having in mind the rate of occurrence and clinical importance, venous thromboembolism implies venous thrombosis and pulmonary embolism as a result of embolisation of the thrombotic particles from deep veins or pelvic veins. Venous thrombosis of the deep veins may result in chronic vein insufficiency, but the primary medical problem is the possibility of development of pulmonary embolism which may cause permanent respiratory function damage or even fatal outcome.

VENOUS THROMBOEMBOLISM PREVENTION IN STROKE

The high incidence of deep vein thrombosis (30% clinically and up to 50% subclinically) in acute stroke hemiparetic and bed ridden patients within two weeks from the onset and 1-2% pulmonary embolism with the fatal outcome in the first month clinically and 17% of all fatal outcomes in postmortem investigations present a necessity for the early venous thromboembolism prevention. On the other hand, the most powerful prevention strategy--anticoagulation has important limitations in acute stroke patients: almost impossible to be used in cerebral haemorrhage and a great risk for the development of haemorrhagic transformation in cerebral infarction. The fact that other prevention strategies have limited value requires an estimation of effectivity-risk ratio in venous thromboembolism prevention in stroke.

CONCLUSION

Venous thromboembolism prevention in stroke patients is necessary because of a greater risk for venous thromboembolism in these patients according to the nature of illness and functional disability, but also a problem because of limited possibility to recommend the proper medicament according to the risk of serious complications. The necessity of preventing venous thromboembolism and estimation of effectivity-risk ratio in stroke patients, beside plenty of studies and consensus conferences, remain individual and often very difficult.

Phosphoinositide 3-kinase induced activation and cytoskeletal translocation of protein kinase CK2 in protease activated receptor 1-stimulated platelets

CK2 is a highly conserved protein kinase involved in several cellular events. CK2 is expressed in platelets but its role in platelet activation remains poorly understood. In the present study, we tested the hypothesis that CK2 plays a role in platelet activation, particularly in the PAR1-dependent signal transduction pathway. The effect of CK2 and PI 3-kinase inhibitors on aggregation of platelets, activation of GPIIb/IIIa, activation and translocation of CK2 was examined. Platelets were incubated with the cell permeable CK2 inhibitors, DRB, DMAT and TBB and stimulated with the PAR1-AP (SFLLRNP). CK2 inhibitors showed the specific inhibitory pattern of platelet aggregation, characterized by a primary phase of aggregation followed by progressive disaggregation. CK2 inhibitors suppressed the activation of GPIIb/IIIa. PAR1-AP induced two-fold increase in CK2 activity and stimulated the translocation of CK2 from Triton X-100-soluble to -insoluble fraction. Preincubation of platelets with the PI 3-kinase inhibitor, wortmannin or LY294002, impaired PAR1-AP-induced aggregation of platelets. PAR1-AP-induced increase in CK2 activity and translocation of CK2 were inhibited by these treatments. Taken together, the present study demonstrated, for the first time, that PI 3-kinase-CK2 pathway plays an important role in the mechanism of PAR1-dependent platelet aggregation.

Prior aspirin use and outcomes in acute coronary syndromes

OBJECTIVES

The purpose of this study was to determine whether patients taking aspirin before an acute coronary syndrome (ACS) are at higher risk of recurrent events or mortality.

BACKGROUND

Controversy exists whether prior aspirin use is an independent predictor of worse outcomes in patients who experience an ACS.

METHODS

We evaluated 66,443 ACS patients from a merged database of previous Thrombolysis in Myocardial Infarction trials. We evaluated the differences in ACS type, total mortality, and the composite end point of death, myocardial infarction (MI), recurrent ischemia, or stroke between prior aspirin and nonprior aspirin users. We used multivariate analysis to control for differences in baseline characteristics.

RESULTS

Prior aspirin users (n = 17,839) were older (63 years vs. 59 years) and had more coronary risk factors and evidence of coronary artery disease (MI, angina, prior intervention) than nonprior aspirin users (n = 48,604) (all p < 0.0001). Prior aspirin use was associated with less severe types of ACS at presentation (e.g., unstable angina > non-ST-segment elevation MI > ST-segment elevation MI) than their nonaspirin user counterparts (p < 0.0001). After multivariate analysis, there was no difference in total mortality between prior aspirin users and nonaspirin users at day 30 (odds ratio [OR]: 1.01; 95% confidence interval [CI]: 0.90 to 1.13) or by the last follow-up visit (mean 328 days) (hazard ratio: 1.03; 95% CI: 0.95 to 1.11). Prior aspirin use was modestly associated with recurrent MI (OR: 1.26; 95% CI: 1.12 to 1.43) and the composite end point (OR: 1.16; 95% CI: 1.08 to 1.24).

CONCLUSIONS

Prior aspirin use was associated with more comorbidities and coronary disease and a higher risk of recurrent MI, but not mortality. As such, it should best be considered a marker of a patient population at high risk for recurrent adverse events after ACS.

Low bone mineral density is not associated with angiographically determined coronary atherosclerosis in men

This study for the first time investigates the association of bone mineral density (BMD) with angiographically determined coronary atherosclerosis in men. Our data show that the prevalence of low BMD is very high in men undergoing coronary angiography. However, neither osteopenia nor osteoporosis is associated with an increased prevalence of angiographically determined coronary atherosclerosis.

INTRODUCTION

The association of low BMD with angiographically determined coronary atherosclerosis in men is unknown.

METHODS

We enrolled 623 consecutive men undergoing coronary angiography for the evaluation of established or suspected coronary artery disease (CAD). BMD was assessed by dual X-ray absorptiometry. CAD was diagnosed in the presence of any coronary artery lumen narrowing at angiography; coronary stenoses with lumen narrowing > or =50% were considered significant.

RESULTS

From the total study cohort (mean age of 64 +/- 11 years), 207 patients (33.2%) had osteopenia and 65 (10.4%) had osteoporosis; at angiography, CAD was diagnosed in 558 patients (89.6%) and 403 (64.7%) had significant coronary stenoses. In multivariate logistic regression analysis neither osteopenia nor osteoporosis was associated with an increased prevalence of CAD (adjusted odds ratios (ORs) = 0.71 [95% confidence interval 0.40-1.23]; p = 0.222 and 1.03 [0.38-2.80]; p = 0.955, respectively) or with significant coronary stenoses (OR 0.74 [0.52-1.07], p = 0.112 and 0.72 [0.41-1.26]; p = 0.251, respectively). Also, as a continuous variable, BMD was not associated with angiographically diagnosed CAD.

CONCLUSIONS

The prevalence of low BMD is very high in men undergoing coronary angiography. However, low BMD is not associated with angiographically determined coronary atherosclerosis in men.

Influence of Vascular Oxidative Stress and Inflammation on the Development and Progression of Atherosclerosis

Cardiovascular disease (CVD) risk factors such as hypertension, diabetes, dyslipidemia, smoking, physical inactivity, and obesity increase production of vascular reactive oxygen species (ROS), which results in a reduction of bioavailable nitric oxide and ultimately endothelial dysfunction and endothelial cell activation. ROS appears to mediate the inflammatory pathways that participate in the development and progression of atherosclerosis. There are numerous markers of oxidative stress and inflammation available for assessing the therapeutic response to interventions, but few are currently recommended for clinical use. Exercise training improves endothelial function via several mechanisms, including increased endothelial nitric oxide synthase—nitric oxide (eNOS-NO)— mediated production, increased activity and amount of antioxidants, attenuated ROS production, and an apparent reduction in systemic inflammation, possibly related to an increase in myokines resulting from skeletal muscle activation. Dietary antioxidant supplementation may improve endothelial function, oxidative stress, and inflammation, but much controversy exists regarding the use of antioxidant supplementation in primary and secondary CVD prevention. The purpose of this article is to review the contribution of vascular oxidative stress and activation of the inflammatory pathways in the pathogenesis of CVD and to review common methods used in clinical research to assess vascular oxidative stress and inflammation in response to therapeutic lifestyle interventions.

PGE2 decreases reactivity of human platelets by activating EP2 and EP4

INTRODUCTION

Platelet hyperreactivity associates with cardiovascular events in humans. Studies in mice and humans suggest that prostaglandin E2 (PGE2) regulates platelet activation. In mice, activation of the PGE2 receptor subtype 3 (EP3) promotes thrombosis, but the significance of EP3 in humans is less well understood.

OBJECTIVES

To characterize the regulation of thromboxane-dependent human platelet activation by PGE2.

PATIENTS/METHODS

Platelets collected from nineteen healthy adults were studied using an agonist of the thromboxane receptor (U46,619), PGE2, and selective agonists and/or antagonists of the EP receptor subtypes. Platelet activation was assayed by (1) optical aggregometry, (2) measurement of dense granule release, and (3) single-platelet counting.

RESULTS

Healthy volunteers demonstrated significant interindividual variation in platelet response to PGE2. PGE2 completely inhibited U46,619-induced platelet aggregation and ATP release in 26% of subjects; the remaining 74% had partial or no response to PGE2. Antagonism of EP4 abolished the inhibitory effect of PGE2. In all volunteers, a selective EP2 agonist inhibited U46,619-induced aggregation. Furthermore, the selective EP3 antagonist DG-041 converted all PGE2 nonresponders to full responders.

CONCLUSIONS

There is significant interindividual variation of platelet response to PGE2 in humans. The balance between EP2, EP3, and EP4 activation determines its net effect. PGE2 can prevent thromboxane-induced platelet aggregation in an EP4-dependent manner. EP3 antagonism converts platelets of nonresponders to a PGE2-responsive phenotype. These data suggest that therapeutic targeting of EP pathways may have cardiovascular benefit by decreasing platelet reactivity.

Intake of Red Wine Increases the Number and Functional Capacity of Circulating Endothelial Progenitor Cells by Enhancing Nitric Oxide Bioavailability

Objective— Red wine (RW) consumption has been associated with a reduction of cardiovascular events, but limited data are available on potential mediating mechanisms. This study tested the hypothesis that intake of RW may promote the circulating endothelial progenitor cell (EPC) level and function through enhancement of nitric oxide bioavailability.

Methods and Results— Eighty healthy, young subjects were randomized and assigned to consume water (100 mL), RW (100 mL), beer (250 mL), or vodka (30 mL) daily for 3 weeks. Flow cytometry was used to quantify circulating EPC numbers, and in vitro assays were used to evaluate EPC functions. After RW ingestion, endothelial function determined by flow-mediated vasodilation was significantly enhanced; however, it remained unchanged after water, beer, or vodka intake. There were significantly increased numbers of circulating EPC (defined as KDR + CD133 + , CD34 + CD133 + , CD34 + KDR + ) and EPC colony-forming units only in the RW group (all P <0.05). Only RW ingestion significantly enhanced plasma levels of nitric oxide and decreased asymmetrical dimethylarginine (both P <0.01). Incubation of EPC with RW (but not beer or ethanol) and resveratrol in vitro attenuated tumor necrosis factor-α–induced EPC senescence and improved tumor necrosis factor-α–suppressed EPC functions and tube formation. Incubation with nitric oxide donor sodium nitroprusside significantly ameliorated the inhibition of tumor necrosis factor-α on EPC proliferation, but incubation with endothelial nitric oxide synthase inhibitor l -NAME and PI3K inhibitor markedly attenuated the effect of RW on EPC proliferation.

Conclusion— The intake of RW significantly enhanced circulating EPC levels and improved EPC functions by modifying nitric oxide bioavailability. These findings may help explain the beneficial effects of RW on the cardiovascular system. This study demonstrated that a moderate intake of RW can enhance circulating levels of EPC in healthy subjects by increasing nitric oxide availability. Direct incubation of EPC with RW and resveratrol can modify the functions of EPC, including attenuation of senescence and promotion of EPC adhesion, migration, and tube formation. These data suggest that RW ingestion may alter the biology of EPC, and these alterations may contribute to its unique cardiovascular-protective effect.