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

Identification of vulnerable atherosclerotic plaques

There has been great interest in the possibility of identifying plaques that might be the site of future acute coronary events. These plaques are termed vulnerable and the majority are lipid-rich with an abundance of inflammatory cells and a thin fibrous cap. Several techniques developed to identify these plaques are in various stages of development and in the near future, one might employ a strategy to potentially identify and therapeutically modify such lesions during percutaneous intervention to avoid future acute events. Although this approach of identifying the vulnerable plaque seems promising, there are significant potential limitations. The natural history of a vulnerable plaque is unknown and clinical trials utilizing this strategy of identification and therapeutic intervention are lacking. Moreover, in any given patient, multiple vulnerable plaques are likely to be present. This article reviews some of the techniques for identifying a vulnerable plaque and discusses the potential advantages and limitations of this strategy.

Mauritia flexuosa Presents In Vitro and In Vivo Antiplatelet and Antithrombotic Activities

Fruit from the palm Mauritia flexuosa is one of the most important species in Peru, Venezuela, Brazil, Colombia, Bolivia, and Guyana. The present study aimed to investigate the antiplatelet and antithrombotic activities of oil extracted from Mauritia flexuosa. The fatty acid contents were determined by gas chromatography—mass spectrometry. Oil extract of peel of Mauritia flexuosa was extracted by soxhlet extraction. The oil extract inhibited platelet secretion and aggregation induced by ADP, collagen, and TRAP-6 by a concentration-dependent way (0.1 to 1 mg/mL) without the participation of the adenylyl cyclase pathway and diminished platelet rolling and firm adhesion under flow conditions. Furthermore, the oil extract induced a marked increase in the rolling speed of leukocytes retained on the platelet surface, reflecting a reduction of rolling and less adhesion. At the concentrations used, the oil extract significantly decreased platelet release of sP-selectin, an atherosclerotic-related inflammatory mediator. Oil extract inhibited thrombus growth at the same concentration as that of aspirin, a classical reference drug. Finally, the data presented herein also demonstrate for the first time to our knowledge the protective effect of oil extracted from Mauritia flexuosa on platelet activation and thrombosis formation.

Evolution of intravascular assessment of coronary anatomy and physiology: from ultrasound imaging to optical and flow assessment

The fact that coronary angiography has limitations in terms of precise estimation and progression of atherosclerosis has been partially overcome during the last years by the use of new techniques. Catheter-based invasive modalities are of a profound clinical importance in regard to accurate assessment of coronary anatomy and physiology and the choice of the appropriate treatment strategy for each patient. Also their potential in clinical investigation projects is of great interest. This current review summarizes the basic principles of these methodologies and evidently highlights not only their use in clinical practice but also their contribution in clinical outcomes.

Relationship between retinal vascular caliber and coronary artery disease in patients with non-alcoholic fatty liver disease (NAFLD)

Objective: To evaluate the relationship between retinal vascular caliber and cardiovascular disease in non-alcoholic fatty liver disease (NAFLD) patients without diabetes and hypertension. Methods: Intention to treat study of individuals who underwent cardiac computed tomography (CT) during a two year period. Coronary artery disease (CAD) was defined as stenosis of >50% in at least one major coronary artery. Liver and spleen density were measured by abdominal (CT); intima-media thickness (IMT) by Doppler ultrasound; retinal artery and vein diameter by colored-retinal angiography; and metabolic syndrome by ATP III guidelines. Serum biomarkers of insulin resistance, inflammation, and oxidant-antioxidant status were assessed. Results: Compared with 22 gender and age matched controls, the 29 NAFLD patients showed higher prevalence of coronary plaques (70% vs. 30%, p < 0.001), higher prevalence of coronary stenosis (30% vs. 15%, p < 0.001), lower retinal arteriole-to-venule ratio (AVR) (0.66 ± 0.06 vs. 0.71 ± 0.02, p < 0.01), higher IMT (0.98 ± 0.3 vs. 0.83 ± 0.1, p < 0.04), higher carotid plaques (60% vs. 40%, p < 0.001), higher homeostasis model assessment of insulin resistance (HOMA) (4.0 ± 3.4 vs. 2.0 ± 1.0, p < 0.005), and higher triglyceride levels (200 ± 80 vs. 150 ± 60, p < 0.005) than controls. Multivariate analysis showed fatty liver (OR 2.5; p < 0.01), IMT (OR 2.3 p < 0.001), and retinal AVR ratio (OR 1.5, p < 0.01) to be strongly associated with CAD independent of metabolic syndrome (OR 1.2, p < 0.05). Conclusions: Patients with smaller retinal AVR (<0.7) are likely to be at increased risk for CAD and carotid atherosclerosis in patients with NAFLD even without hypertension or diabetes.

Optimizing the imaging protocol for ex vivo coronary artery wall using high-resolution MRI: an experimental study on porcine and human

Objective

To optimize the MR imaging protocol for coronary arterial wall depiction in vitro and characterize the coronary atherosclerotic plaques.

Materials and Methods

MRI examination was prospectively performed in ten porcine hearts in order to optimize the MR imaging protocol. Various surface coils were used for coronary arterial wall imaging with the same parameters. Then, the image parameters were further optimized for high-resolution coronary wall imaging. The signal-noise ratio (SNR) and contrast-noise ratio (CNR) of images were measured. Finally, 8 human cadaver hearts with coronary atherosclerotic plaques were prospectively performed with MRI examination using optimized protocol in order to characterize the coronary atherosclerotic plaques.

Results

The SNR and CNR of MR image with temporomandibular coil were the highest of various surface coils. High-resolution and high SNR and CNR for ex vivo coronary artery wall depiction can be achieved using temporomandibular coil with 512 × 512 in matrix. Compared with histopathology, the sensitivity and specificity of MRI for identifying advanced plaques were: type IV-V (lipid, necrosis, fibrosis), 94% and 95%; type VI (hemorrhage), 100% and 98%; type VII (calcification), 91% and 100%; and type VIII (fibrosis without lipid core), 100% and 98%, respectively.

Conclusion

Temporomandibular coil appears to be dramatically superior to eight-channel head coil and knee coil for ex vivo coronary artery wall imaging, providing higher spatial resolution and improved the SNR. Ex vivo high-resolution MRI has capability to distinguish human coronary atherosclerotic plaque compositions and accurately classify advanced plaques.

Mean platelet volume reproducibility and association with platelet activity and anti-platelet therapy

Some studies suggest that mean platelet volume (MPV) correlates with increased risk for cardiovascular morbidity and mortality. In this study, we aim to assess reproducibility, need for standardized measurements, effect of aspirin, and association with other established markers of platelet activity. Following an overnight fast, 48 healthy volunteers had weekly assessment of platelet activity and were administered aspirin 81 mg daily for 7 d between weeks 3 and 4. We investigated the influence of time between phlebotomy and MPV measurement (n=10). Reproducibility was assessed by coefficient of variation (CV) and intraclass correlation coefficient (ICC). MPV measurements were reproducible (Week 1: 10.6 fL [9.9-11], Week 2: 10.6 fL [10.0-10.9], Week 3: 10.6 fL [9.8-11]). CV was ≤ 4% and ICC>0.85 (p<0.001) for each comparison, indicating excellent reproducibility. There was no effect of aspirin on MPV (10.6 fL [9.8-11] versus 10.5 fL [9.9-11]; p=0.81). MPV significantly increased as time between phlebotomy and MPV measurement increased (Spearman's rho=0.94, p=0.001). Increasing MPV tertiles was associated with collagen- and thrombin receptor-activated peptide-induced platelet aggregation but not with ADP- or arachidonic acid-induced or spontaneous platelet aggregation. In conclusion, when standardized, MPV is a reproducible marker of platelet size and not affected by low-dose aspirin. MPV is modestly associated with some, but not all, markers of platelet activity.

Impact of anticoagulation on coronary flow in patients with non-ST elevation acute coronary syndrome

The effect of anticoagulation by heparin on patients with non-ST elevation acute coronary syndrome (NSTE-ACS), receiving early dual antiplatelet therapy, has not been fully evaluated. We classified 355 patients with NSTE-ACS according to the adequacy of anticoagulation (percentage of low activated partial thromboplastin time [APTT] level). The 6-hour APTT level was optimal in only 23.1% of the patients treated with unfractionated heparin. The rate of poor preprocedural coronary blood flow (thrombolysis in myocardial infarction grade <3, 39.1%, 30.5%, 30.3%, and 33.9% in the 100% low-, 99%∼50% low-, 49%∼1% low-, and 0% low-APTT group, respectively, P = .632) and bleeding events did not differ between the groups. Instead, in multivariate analysis, the diagnosis of myocardial infarction was the only independent predictor of poor coronary flow. For bleeding events, the usage of glycoprotein IIb/IIIa inhibitor appeared to be a sole risk factor. In conclusion, inadequate preprocedural anticoagulation was not associated with adverse outcomes in patients with NSTE-ACS treated with dual antiplatelet agents.

Histopathologic characteristics of atherosclerotic coronary disease and implications of the findings for the invasive and noninvasive detection of vulnerable plaques

OBJECTIVES

The goal of this study was to identify histomorphologic characteristics of atherosclerotic plaques and to determine the amenability of some of these components to be used as markers for invasive and noninvasive imaging.

BACKGROUND

Rupture of the atherosclerotic plaques is responsible for the majority of acute coronary events, and the culprit lesions demonstrate distinct histopathologic features. It has been tacitly believed that plaque rupture (PR) is associated with angiographically minimally occlusive lesions.

METHODS

We obtained 295 coronary atherosclerotic plaques, including stable (fibroatheroma [FA]; n = 105), vulnerable (thin-cap fibroatheroma [TCFA]; n = 88), and disrupted plaques (plaque rupture [PR]; n = 102) from the hearts of 181 men and 32 women who had died suddenly. The hierarchical importance of fibrous cap thickness, percent luminal stenosis, macrophage area, necrotic core area, and calcified plaque area was evaluated by using recursive partitioning analysis. Because clinical assessment of fibrous cap thickness is not possible by noninvasive imaging, it was excluded from the second set of partitioning analysis.

RESULTS

Thickness of the fibrous cap emerged as the best discriminator of plaque type; the cap thickness measured <55 μm in ruptured plaques, and all FA were associated with >84-μm cap thickness. Although the majority of TCFA were found in the 54- to 84-μm thickness group, those with <54-μm thickness were more likely to show <74% luminal stenosis (area under the curve: FA, 1.0; TCFA, 0.89; PR, 0.90). After exclusion of cap thickness, analysis of the plaque characteristics revealed macrophage infiltration and necrotic core to be the 2 best discriminators of plaque types (area under the curve: FA, 0.82; TCFA, 0.58; PR, 0.72). More than 75% cross-section area stenosis was seen in 70% of PR and 40% of TCFA; only 5% PR and 10% TCFA were <50% narrowed.

CONCLUSIONS

This postmortem study defines histomorphologic characteristics of vulnerable plaques, which may help develop imaging strategies for identification of such plaques in patients at a high risk of sustaining acute coronary events.

Patients who require non-cardiac surgery in acute coronary syndrome

The coexistence of an acute coronary syndrome (ACS) and non-cardiac surgery (NCS) in an individual patient can be summarized in two challenging clinical scenarios for the treating physician: 1) Post-operative patients who develop ACS and 2) Patients with ACS who subsequently require NCS. Both settings are characterized by a struggle on the part of treating physicians attempting to optimize antithrombotic therapies for ACS while minimizing post-surgical bleeding risk. In this review we address specific clinical issues related to patients with coexistent NCS and ACS, discussing possible management strategies balancing ischemic and bleeding risk in these complex patient scenarios.

Flow recirculation zone length and shear rate are differentially affected by stenosis severity in human coronary arteries

Flow recirculation zones and shear rate are associated with distinct pathogenic biological pathways relevant to thrombosis and atherogenesis. The interaction between stenosis severity and lesion eccentricity in determining the length of flow recirculation zones and peak shear rate in human coronary arteries in vivo is unclear. Computational fluid dynamic simulations were performed under resting and hyperemic conditions on computer-generated models and three-dimensional (3-D) reconstructions of coronary arteriograms of 25 patients. Boundary conditions for 3-D reconstructions simulations were obtained by direct measurements using a pressure-temperature sensor guidewire. In the computer-generated models, stenosis severity and lesion eccentricity were strongly associated with recirculation zone length and maximum shear rate. In the 3-D reconstructions, eccentricity increased recirculation zone length and shear rate when lesions of the same stenosis severity were compared. However, across the whole population of coronary lesions, eccentricity did not correlate with recirculation zone length or shear rate ( P = not signficant for both), whereas stenosis severity correlated strongly with both parameters ( r = 0.97, P < 0.001, and r = 0.96, P < 0.001, respectively). Nonlinear regression analyses demonstrated that the relationship between stenosis severity and peak shear was exponential, whereas the relationship between stenosis severity and recirculation zone length was sigmoidal, with an apparent threshold effect, demonstrating a steep increase in recirculation zone length between 40% and 60% diameter stenosis. Increasing stenosis severity and lesion eccentricity can both increase flow recirculation and shear rate in human coronary arteries. Flow recirculation is much more sensitive to mild changes in the severity of intermediate stenoses than is peak shear.

Comparison of iodinated contrast media for the assessment of atherosclerotic plaque attenuation values by CT coronary angiography: observations in an ex vivo model

OBJECTIVE

To compare the influence of different iodinated contrast media with several dilutions on plaque attenuation in an ex vivo coronary model studied by multislice CT coronary angiography.

METHODS

In six ex vivo left anterior descending coronary arteries immersed in oil, CT (slices/collimation 64×0.625 mm, temporal resolution 210 ms, pitch 0.2) was performed after intracoronary injection of a saline solution, and solutions of a dimeric isosmolar contrast medium (Iodixanol 320 mgI ml(-1)) and a monomeric high-iodinated contrast medium (Iomeprol 400 mgI ml(-1)) with dilutions of 1/80 (low concentration), 1/50 (medium concentration), 1/40 (high concentration) and 1/20 (very high concentration). Two radiologists drew regions of interest in the lumen and in calcified and non-calcified plaques for each solution. 29 cross-sections with non-calcified plaques and 32 cross-sections with calcified plaques were evaluated.

RESULTS

Both contrast media showed different attenuation values within lumen and plaque (p<0.0001). The correlation between lumen and non-calcified plaque values was good (Iodixanol r=0.793, Iomeprol r=0.647). Clustered medium- and high-concentration solutions showed similar plaque attenuation values, signal-to-noise ratios (SNRs) (non-calcified plaque: medium solution SNR 31.3±15 vs 31.4±20, high solution SNR 39.4±17 vs 37.4±22; calcified plaque: medium solution SNR 305.2±133 vs 298.8±132, high solution SNR 323.9±138 vs 293±123) and derived contrast-to-noise ratios (p>0.05).

CONCLUSION

Differently iodinated contrast media have a similar influence on plaque attenuation profiles.

ADVANCES IN KNOWLEDGE

Since iodine load affects coronary plaque attenuation linearly, different contrast media may be equally employed for coronary atherosclerotic plaque imaging.

Evidence for the role of Epstein Barr Virus infections in the pathogenesis of acute coronary events

BACKGROUND

The role of viral infections in the pathogenesis of atherosclerosis remains controversial largely due to inconsistent detection of the virus in atherosclerotic lesions. However, viral infections elicit a pro-inflammatory cascade known to be atherogenic and to precipitate acute ischemic events. We have published in vitro data that provide the foundation for a mechanism that reconciles these conflicting observations. To determine the relation between an early viral protein, deoxyuridine triphosphate nucleotidohydrolase (dUTPase), produced following reactivation of Epstein Barr Virus (EBV) to circulating pro-inflammatory cytokines, intercellular adhesion molecule-1 (ICAM-1) and acute coronary events.

METHODOLOGY/PRINCIPAL FINDINGS

Blood samples were obtained from 299 patients undergoing percutaneous coronary intervention for stable angina (SA), unstable angina (UA), or acute myocardial infarction (AMI). Plasma concentrations of pro-inflammatory cytokines and neutralizing antibody against EBV-encoded dUTPase were compared in the three patient groups. AMI was associated with the highest measures of interleukin-6 (ANOVA p<0.05; 4.6 ± 2.6 pg/mL in patients with AMI vs. 3.2 ± 2.3 pg/mL in SA). ICAM-1 was significantly higher in patients with AMI (ANOVA p<0.05; 304 ± 116 pg/mL in AMI vs. 265 ± 86 pg/mL SA). The highest values of ICAM-1 were found in patients having an AMI and who were antibody positive for dUTPase (ANOVA p=0.008; 369 ± 183 pg/mL in AMI and positive for dUTPase vs. 249 ± 70 pg/mL in SA negative for dUTPase antibody).

CONCLUSIONS/SIGNIFICANCE

These clinical data support a model, based on in vitro studies, by which EBV may precipitate AMI even under conditions of low viral load through the pro-inflammatory action of the early protein dUTPase that is produced even during incomplete viral replication. They further support the putative role of viral infections in the pathogenesis of atherosclerosis and coronary artery events.

Platelet flow cytometry

Flow cytometry is a powerful and versatile tool which can be used to provide substantial phenotypic data on platelets by yielding quantitative information of their physical and antigenic properties. This includes surface expression of functional receptors, bound ligands, expression of granule components, interaction of platelets with other platelets via aggregation, or interaction with other blood components, such as leukocytes or the plasma coagulation system. Quantitative assessment of these parameters may facilitate the diagnosis of inherited or acquired platelet disorders, assist in the diagnosis of diseases associated with platelet activation, or assist in the monitoring of safety and efficacy of antiplatelet therapy.

Novel direct-acting anticoagulants for risk reduction in ACS

Acute coronary syndrome (ACS) is a devastating adverse cardiovascular event with a massive burden on patient morbility and mortality, as well as the economy. Approximately 1.2 million people are hospitalized annually for ACS in the United States, with direct medical costs estimated at $150 billion in 2009. Rehospitalization is common, often as the result of recurrence of the initial event or complications of ACS or its therapy. Thrombosis is central to the pathogenesis of ACS. The current standard of care includes dual antiplatelet therapy, which reduces platelet activation and aggregation, integral steps for forming a thrombus. However, antiplatelet therapy does not prevent continued thrombin generation or the deposition of fibrin in the clot and residual risk of a recurrent event remains high. New oral anticoagulants offer a mechanism of action that is different from and complementary to that of antiplatelet agents. The ATLAS ACS-TIMI 51 (Anti-Xa Therapy to Lower Cardiovascular Events in Addition to Standard Therapy in Subjects with Acute Coronary Syndrome-Thrombolysis in Myocardial Infarction 51) trial, using rivaroxaban, is the first trial of the new oral anticoagulants to show a benefit when added to antiplatelet therapy in reducing ACS events and mortality. While there was more major bleeding with the addition of rivaroxaban, fatal bleeding was not increased. These agents, if added to the current standard of care, might substantially reduce the high clinical and economic consequences of ACS.

Reduced number and impaired function of circulating endothelial progenitor cells in patients with abdominal aortic aneurysm

AIM

Circulating endothelial progenitor cells (EPCs) are associated with coronary artery disease (CAD) and predict its outcome. Although the pathophysiology of abdominal aortic aneurysm (AAA) is different, it shares some risk factors with CAD. Therefore, the correlation between EPCs and AAA was investigated.

METHODS AND RESULTS

Seventy-eight subjects (age 77.2 ± 7.8 years) with suspected AAA were prospectively enrolled. Cut-off values (men, 3.5-5.5 cm; women, 3-5 cm) were used to define normal aorta, small AAA, and large AAA on thoraco-abdominal computer tomography. Endothelial function was measured by flow-mediated vasodilation (FMD). Flow cytometry and colony-forming units (CFUs) were used to evaluate circulating EPC numbers. Circulating EPCs were defined as mononuclear cells with low CD45 staining and double-positive staining for KDR, CD34, or CD133. Late out-growth EPCs were cultured from six patients with large AAAs and six age- and sex-matched controls to evaluate proliferation, adhesion, migration, tube formation, and senescence. FMD was significantly lower with large (5.26% ± 3.11%) and small AAAs (6.31% ± 3.66%) than in controls (8.88% ± 4.83%, P=0.008). Both CFUs (normal 38.39 ± 12.99, small AAA 21.22 ± 7.14, large AAA 6.98 ± 1.97; P=0.026) and circulating EPCs (CD34(+)/KDR(+) and CD133(+)/KDR(+)) were significantly fewer in AAA patients than in controls. On multivariate analysis, CFUs and circulating EPCs (CD34(+)/KDR(+)) were independently, inversely correlated to AAA diameter. Proliferation, adhesion, migration, tube formation, and senescence of late EPCs were significantly impaired in AAA patients.

CONCLUSION

The number and function of EPCs were impaired in AAA patients, suggesting their potential role in AAA.

Glycine reduces platelet aggregation

It has been demonstrated that a wide variety of white blood cells and macrophages (i.e. Kupffer cells, alveolar and peritoneal macrophages and neutrophils) contain glycine-gated chloride channels. Binding of glycine on the receptor stimulates Cl(-) influx causing membrane hyperpolarization that prevents agonist-induced influx of calcium. Since platelet-aggregation is calcium-dependent, this study was designed to test the hypothesis that glycine would inhibit platelet aggregation. Rats were fed diets rich of glycine for 5 days, while controls received isonitrogenous valine. The bleeding time and ADP- and collagen-induced platelet aggregation were measured. Dietary glycine significantly increased bleeding time about twofold compared to valine-treated controls. Furthermore, the amplitude of platelet aggregation stimulated with ADP or collagen was significantly decreased in whole blood drawn from rats fed 2.5 or 5 % dietary glycine by over 50 %. Addition of glycine in vitro (1-10 mM) also blunted rat platelet aggregation in a dose-dependent manner. Strychnine, a glycine receptor antagonist, abrogated the inhibitory effect of glycine on platelet-aggregation in vitro suggesting the glycine works via a glycine receptor. Glycine also blunted aggregation of human platelets. Further, the glycine receptor was detected in both rat and human platelets by western blotting. Based on these data, it is concluded that glycine prevents aggregation of platelets in a dose-dependent manner via mechanisms involving a glycine receptor.

30-day in-hospital mortality after acute myocardial infarction in Tuscany (Italy): an observational study using hospital discharge data

Background

Coronary heart disease is the leading cause of mortality in the world. One of the outcome indicators recently used to measure hospital performance is 30-day mortality after acute myocardial infarction (AMI). This indicator has proven to be a valid and reproducible indicator of the appropriateness and effectiveness of the diagnostic and therapeutic process for AMI patients after hospital admission. The aim of this study was to examine the determinants of inter-hospital variability on 30-day in-hospital mortality after AMI in Tuscany. This indicator is a proxy of 30-day mortality that includes only deaths occurred during the index or subsequent hospitalizations.

Methods

The study population was identified from hospital discharge records (HDRs) and included all patients with primary or secondary ICD-9-CM codes of AMI (ICD-9 codes 410.xx) that were discharged between January 1, 2009 and November 30, 2009 from any hospital in Tuscany. The outcome of interest was 30-day all-cause in-hospital mortality, defined as a death occurring for any reason in the hospital within 30 days of the admission date. Because of the hierarchical structure of the data, with patients clustered into hospitals, random-effects (multilevel) logistic regression models were used. The models included patient risk factors and random intercepts for each hospital.

Results

The study included 5,832 patients, 61.90% male, with a mean age of 72.38 years. During the study period, 7.99% of patients died within 30 days of admission. The 30-day in-hospital mortality rate was significantly higher among patients with ST segment elevation myocardial infarction (STEMI) compared with those with non-ST segment elevation myocardial infarction (NSTEMI). The multilevel analysis which included only the hospital variance showed a significant inter-hospital variation in 30-day in-hospital mortality. When patient characteristics were added to the model, the hospital variance decreased. The multilevel analysis was then carried out separately in the two strata of patients with STEMI and NSTEMI. In the STEMI group, after adjusting for patient characteristics, some residual inter-hospital variation was found, and was related to the presence of a cardiac catheterisation laboratory.

Conclusion

We have shown that it is possible to use routinely collected administrative data to predict mortality risk and to highlight inter-hospital differences. The distinction between STEMI and NSTEMI proved to be useful to detect organisational characteristics, which affected only the STEMI subgroup.

Persistent angina pectoris, cardiac mortality and myocardial infarction during a 12 year follow-up in 273 variant angina patients without significant fixed coronary stenosis

The incidence of cardiac events in patients with variant angina pectoris without significant coronary stenosis and ST-segment elevation was analyzed during a 12-year follow-up period in 273 consecutive patients (82% men) admitted from 1986 through 2010. Among the 252 patients who underwent electrocardiography during pain, 205 had ST-segment elevation (82%) and 45 had ST-segment depression (18%). During index hospitalization, angina occurred in 179 patients (66%), ventricular tachycardia or fibrillation in 28 (10%), and complete atrioventricular block in 3 (1%), but there were no deaths or myocardial infarctions (MIs). At 140 months, angina was still present in 129 patients (47%), but frequent angina (>10 episodes/year) occurred in only 6%. Total mortality, cardiac mortality, and MI rates were 24%, 7.0%, and 6%, respectively. Cardiac death or MI occurred in 28 patients (10%), associated with tobacco smoking (p = 0.004), antecedent "first-wind" angina (p = 0.020), and angina during hospitalization (p = 0.044) and with continued smoking (p = 0.056) and recurrent angina during follow-up (p <0.001). Multivariate analysis identified age (p = 0.001), antecedent infarction (p = 0.005), first-wind angina (p = 0.009), and smoking at index hospitalization (p = 0.027) as predictors of total mortality and treatment with calcium antagonists (p = 0.047) and smoking during follow-up (p = 0.110) for cardiac mortality and MI. In conclusion, during 12-year follow-up, patients with variant angina pectoris, mostly with ST-segment elevation during pain, had a reduced incidence of cardiac mortality and MI, associated with first-wind angina, persistent angina, and continued smoking.

Current perspectives on laboratory markers for the assessment of cardiovascular disease and myocardial damage

The disruption of the endothelim is a prelude to the evolution of arteriosclerosis. Nitric oxide is critical to endothelial function. The oxidation of low density lipoprotein (LDL) mediated by small dense LDL particles contributes to the development of cardiovascular disease. The multiple effects of homocysteine including its potentiating the binding of lipoprotein(a) (LP(a)) to fibrin and its role in the formation of small dense LDL particles highlights its importance in the evolution of cardiovascular disease and justifies its measurement. Problems in measurement of homocysteine should be kept in perspective. The measurement of release of proteins from the cardiac contractile apparatus such as Troponin I has advantages over conventional measurement of cardiac enzymes and isozymes.

Relation between popliteal-tibial artery atherosclerosis and global glycolytic metabolism in the affected diabetic foot: a pilot study using quantitative FDG-PET

BACKGROUND

We evaluated the extent and the degree of active atherosclerosis in the popliteal-tibial arteries by quantitative techniques using [(18)F]-2-fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET). An effort was made to determine whether there was a positive correlation between the level of ongoing atherosclerosis and subsequent chronic ischemia in the diabetic foot.

METHODS

A total of 115 diabetic patients were enrolled in this prospective research study and underwent lower-extremity FDG-PET and magnetic resonance imaging. We selected 36 diabetic patients with complicated diabetic foot for this analysis (11 men, 25 women; mean age, 59.5 years; age range, 36-85 years). Ten nondiabetic control participants (6 men, 4 women; mean age, 59.7 years; age range, 27-88 years) were also included for comparison. Only patients with blood glucose levels less than 200 mg/100 mL were enrolled in this study. The metabolic volumetric product (MVP), for each patient was calculated multiplying foot average maximum standard uptake value (SUV(max)) by foot volume. Pearson correlation analysis between foot mean SUV(max) alone and the degree of atherosclerosis and between the foot MVP and the degree of atherosclerosis was performed as measured by FDG-PET. A t test was used to assess for significant differences in foot SUV(max) and foot MVP among varying degrees of atherosclerosis, using P < .05 as the criterion for statistical significance.

RESULTS

Foot SUV(max) significantly correlated (P < .05) with the ratio of popliteal-tibial artery SUV(max) to background SUV (Pearson correlation coefficient = 0.49). Foot MVP was also significantly correlated (P < .05) with the ratio of popliteal-tibial artery SUV(max) to background SUV (Pearson correlation coefficient = 0.69).

CONCLUSIONS

Using FDG-PET, one may be able to detect and quantify the degree of increased metabolic activity of early active atherosclerosis and the associated chronic tissue ischemic effects at the regional level and globally throughout the whole body during the asymptomatic phase of disease.

Shear-induced Filter Blockage. A Population Based Appraisal of a Method for the Assessment of Platelet, White Cell and von Willebrand Factor Interactions

Blood behaviour under shear-stress is assessed by a filter method in the Caerphilly Prospective Heart Study. Associations with haemostatic and lifestyle factors in 941 men aged 55 to 69 years are reported. The importance of platelets in filter blockage is confirmed, and roles for white cells and plasma viscosity in determining flow prior to blockage are identified. The aspect of platelet activity involved in blockage appears to be independent of mechanisms mediated by cyclo-oxygenase and adenosine diphosphate. von Willebrand factor however is associated with filter blockage, probably as an inter-platelet ligand. Fibrinogen is not required for blockage. Men regularly consuming alcohol or garlic supplements show reduced blockage, and biochemical mechanisms are suggested which might explain these associations. No effects of aspirin, smoking or consumption of fish oil supplements were noted. Shear-induced filter blockage is a simple method for measuring complex flow-dependent interactions of haemostatic factors. Its application in a wide range of investigations, including epidemiological studies, would appear to be appropriate.

The role of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors (statins) in modern rheumatology

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase commonly known as statins are widely used for treating hypercholesterolemia. However, there is much evidence to suggest that statins may have other properties in addition to their cholesterol-lowering effect. In particular, statins may neutralize post-translational prenylation of vitally important regulatory small GTPases, which are involved in several processes such as tissue fibrosis, cell maturation, apoptosis, immune cell maturation, and immune response. The beneficial effect of statins has been reported in animal and in vitro models as well as in some clinical studies. As they have an acceptable safety profile, statins may be considered, in selected cases, as a valuable concomitant therapy in the treatment of rheumatic and autoimmune disorders.

Identification of the active region responsible for the anti-thrombotic activity of anopheline anti-platelet protein from a malaria vector mosquito

We previously identified an anti-platelet protein, anopheline anti-platelet protein (AAPP), from the salivary gland of female Anopheles stephensi (a mosquito vector of human malaria). AAPP specifically blocks platelet adhesion to collagen by binding directly to collagen and subsequently causing platelet aggregation. The aim of this study was to identify the active region of AAPP responsible for the anti-thrombotic activity because we hypothesized that AAPP could be used as a candidate anti-platelet drug. Various truncated forms of AAPP were produced using an Escherichia coli expression system. Each protein was examined for binding activities to soluble/fibrillar collagen and anti-thrombotic activity using a plate assay and platelet/whole blood aggregation study, respectively. Among the truncated forms examined, only a protein encoded by exon 3-4 (rAAPPex3-4) effectively bound to soluble/fibrillar collagen in a concentration-dependent and saturable manner. The EC50 values of full-length AAPP and rAAPPex3-4 for soluble collagen binding were 35 nM and 36 nM, respectively. In contrast to soluble collagen, there was a difference in binding affinity to fibrillar collagen between full-length AAPP and rAAPPex3-4, with EC50 values of 31 nM and 51 nM, respectively. rAAPPex3-4 also inhibited aggregation of platelets/whole blood, and the IC50 values of full-length AAPP and rAAPPex3-4 for platelet aggregation were 35 nM and 93 nM, respectively. These results indicated that the essential moiety of AAPP for collagen binding and anti-thrombotic activity was in the region encoded by exon 3-4, which is highly conserved among the counterpart regions of other mosquito species.

Oral health status of patients with acute coronary syndrome--a case control study

Background

The aim of this investigation was to assess the state of oral health of patients with acute coronary syndrome (ACS) and to compare this with that of a provably healthy control group (H).

Methods

33 patients who were receiving treatment as inpatients following acute myocardial infarction or unstable angina pectoris took part in the study (ACS-group). A healthy control group (H-group) made up of blood donors, was formed following matching for age, gender, and smoking habit with the study patient group.

The dental investigation consisted of the dental status (DMF-T), a plaque-Index (PI), an assessment of gingival inflammation (GI) and periodontal situation (Periodontal Screening Index: PSR®/PSI), and attachment loss (AL). Statistical evaluation: t-test, Mann–Whitney-test and chi- squared test (level of significance p < 0.05).

Results

The mean DMF-T of the ACS-group (18.7 ± 6.8) and the H-group (19.4 ± 5.1) showed no difference (p = 0.7). Although, in the ACS-group the average loss of teeth (M-T: 8.4 ± 5.2) was higher than in the H-group (M-T: 5.8 ± 6.6) the difference was not significant (p = 0.2). Whereas with the PI no difference between the two groups was found (p = 0.9), the ACS-group showed significantly more signs of inflammation (GI) than the H-group (p = 0.045). In the case of PSR®/PSI, there was no difference between the two groups (p = 0.7). With regard to AL, no difference was revealed between ACS- and H-group (p = 0.2).

Conclusion

Although, the state of oral health of the ACS-group differed only insignificantly from that of control, patients with ACS showed more signs of gingival inflammation and a higher loss of teeth.

A2 adenosine receptors and vascular pathologies

Cardiovascular disease, a leading cause of death and morbidity, is regulated, among various factors, by inflammation. The level of the metabolite adenosine is augmented under stress, including inflammatory, hypoxic, or injurious events. Adenosine has been shown to affect various physiological and pathological processes, largely through 1 or more of its 4 types of receptors: the A1 and A3 adenylyl cyclase inhibitory receptors and the A2A and A2B adenylyl cyclase stimulatory receptors. This article focuses on reviewing common and distinct effects of the 2 A2-type adenosine receptors on vascular disease and the mechanisms involved. Understanding the pathogenesis of vascular disease mediated by these receptors is important to the development of therapeutics and to the prevention and management of disease.

Decreased circulating endothelial progenitor cell levels and function in patients with nonalcoholic fatty liver disease

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is associated with advanced atherosclerosis and a higher risk of cardiovascular disease. Increasing evidence suggests that injured endothelial monolayer is regenerated by circulating bone marrow derived-endothelial progenitor cells (EPCs), and levels of circulating EPCs reflect vascular repair capacity. However, the relation between NAFLD and EPC remains unclear. Here, we tested the hypothesis that patients with nonalcoholic fatty liver disease (NAFLD) might have decreased endothelial progenitor cell (EPC) levels and attenuated EPC function.

METHODS AND RESULTS

A total of 312 consecutive patients undergoing elective coronary angiography because of suspected coronary artery disease were screened and received examinations of abdominal ultrasonography between July 2009 and November 2010. Finally, 34 patients with an ultrasonographic diagnosis of NAFLD, and 68 age- and sex-matched controls without NAFLD were enrolled. Flow cytometry with quantification of EPC markers (defined as CD34(+), CD34(+)KDR(+), and CD34(+)KDR(+)CD133(+)) in peripheral blood samples was used to assess circulating EPC numbers. The adhesive function, and migration, and tube formation capacities of EPCs were also determined in NAFLD patients and controls. Patients with NAFLD had a significantly higher incidence of metabolic syndrome, previous myocardial infarction, hyperuricemia, and higher waist circumference, body mass index, fasting glucose and triglyceride levels. In addition, patients with NAFLD had significantly decreased circulating EPC levels (all P<0.05), attenuated EPC functions, and enhanced systemic inflammation compared to controls. Multivariate logistic regression analysis showed that circulating EPC level (CD34(+)KDR(+) [cells/10(5) events]) was an independent reverse predictor of NAFLD (Odds ratio: 0.78; 95% confidence interval: 0.69-0.89, P<0.001).

CONCLUSIONS

NAFLD patients have decreased circulating EPC numbers and functions than those without NAFLD, which may be one of the mechanisms to explain atherosclerotic disease progression and enhanced cardiovascular risk in patients with NAFLD.

S100A8/A9 aggravates post-ischemic heart failure through activation of RAGE-dependent NF-κB signaling

The extracellular heterodimeric protein S100A8/A9 activates the innate immune system through activation of the receptor of advanced glycation end products (RAGE) and Toll-like receptors. As activation of RAGE has recently been associated with sustained myocardial inflammation and heart failure (HF) we studied the role of S100A8/A9 in the development of post-ischemic HF. Hypoxia led to sustained induction of S100A8/A9 accompanied by increased nuclear factor (NF-)κB binding activity and increased expression of pro-inflammatory cytokines in cardiac fibroblasts and macrophages. Knockdown of either S100A8/A9 or RAGE rescued the induction of pro-inflammatory cytokines and NF-κB activation after hypoxia. In a murine model of post-ischemic HF both cardiac RNA and protein levels of S100A8/A9 were elevated as soon as 30 min after hypoxia with sustained activation up to 28 days after ischemic injury. Treatment with recombinant S100A8/A9 resulted in reduced cardiac performance following ischemia/reperfusion. Chimera experiments after bone marrow transplantation demonstrated the importance of RAGE expression on immune cells for their recruitment to the injured myocardium aggravating post-ischemic heart failure. Signaling studies in isolated ventricles indicated that MAP kinases JNK, ERK1/2 as well as NF-κB mediate signals downstream of S100A8/A9-RAGE in post-ischemic heart failure. Interestingly, cardiac performance was not affected by administration of S100A8/A9 in RAGE(-/-)-mice, which demonstrated significantly improved cardiac recovery compared to WT-mice. Our study provides evidence that sustained activation of S100A8/A9 critically contributes to the development of post-ischemic HF driving the progressive course of HF through activation of RAGE.

Vitamin B6 and cardiovascular disease

While overt vitamin B6 deficiency is not a frequent finding nowadays in medical practice, evidence suggests that insufficiency of this vitamin is rather widespread in a quite large portion of the population such as the elderly or in not unusual conditions such as that of alcohol addiction. Moreover, a mild deficiency in B6 vitamin is a state that may be associated with an increased risk of cardiovascular disease. Epidemiologic evidence from case control and prospective studies have suggested that low dietary intake or reduced blood concentrations of vitamin B6 is associated with an increased risk of cardiovascular disease, although most recent trials demonstrated the ineffectiveness of vitamin B6 supplementation on the prevention of cardiovascular events recurrence. Due to limited and somewhat inconsistent data together with the ample variety of critical functions in which vitamin B6 is involved in the human body, it is very challenging to attempt at establishing a cause and effect relationship between vitamin B6 and risk of cardiovascular disease as it is to delineate the exact mechanism(s) by which vitamin B6 may modulate such risk. In the present chapter we review the currently available knowledge deriving from both epidemiological and mechanistic studies designed to define potential candidate mechanisms for the association of vitamin B6 impairment and risk of cardiovascular disease development.