Age-related changes in plaque composition

The Effects of FABP4 on Cardiovascular Disease in the Aging Population

PURPOSE OF REVIEW

Fatty acid-binding protein 4 (FABP4) plays a role in lipid metabolism and cardiovascular health. In this paper, we cover FABP4 biology, its implications in atherosclerosis from observational studies, genetic factors affecting FABP4 serum levels, and ongoing drug development to target FABP4 and offer insights into future FABP4 research.

RECENT FINDINGS

FABP4 impacts cells through JAK2/STAT2 and c-kit pathways, increasing inflammatory and adhesion-related proteins. In addition, FABP4 induces angiogenesis and vascular smooth muscle cell proliferation and migration. FABP4 is established as a reliable predictive biomarker for cardiovascular disease in specific at-risk groups. Genetic studies robustly link PPARG and FABP4 variants to FABP4 serum levels. Considering the potential effects on atherosclerotic lesion development, drug discovery programs have been initiated in search for potent inhibitors of FABP4. Elevated FABP4 levels indicate an increased cardiovascular risk and is causally related to acceleration of atherosclerotic disease, However, clinical trials for FABP4 inhibition are lacking, possibly due to concerns about available compounds' side effects. Further research on FABP4 genetics and its putative causal role in cardiovascular disease is needed, particularly in aging subgroups.

A Non-Coronary, Peripheral Arterial Atherosclerotic Disease (Carotid, Renal, Lower Limb) in Elderly Patients-A Review: Part I-Epidemiology, Risk Factors, and Atherosclerosis-Related Diversities in Elderly Patients

Atherosclerosis is a generalized and progressive disease. Ageing is a key risk factor for atherosclerosis progression that is associated with the increased incidence of ischemic events in supplied organs, including stroke, coronary events, limb ischemia, or renal failure. Cardiovascular disease is the leading cause of death and major disability in adults ≥ 75 years of age. Atherosclerotic occlusive disease affects everyday activity and quality of life, and it is associated with reduced life expectancy. Although there is evidence on coronary artery disease management in the elderly, there is insufficient data on the management in older patients presented with atherosclerotic lesions outside the coronary territory. Despite this, trials and observational studies systematically exclude older patients, particularly those with severe comorbidities, physical or cognitive dysfunctions, frailty, or residence in a nursing home. This results in serious critical gaps in knowledge and a lack of guidance on the appropriate medical treatment and referral for endovascular or surgical interventions. Therefore, we attempted to gather data on the prevalence, risk factors, and management strategies in patients with extra-coronary atherosclerotic lesions.

Predicting the Length of Stay of Cardiac Patients Based on Pre-Operative Variables-Bayesian Models vs. Machine Learning Models

Length of stay (LoS) prediction is deemed important for a medical institution's operational and logistical efficiency. Sound estimates of a patient's stay increase clinical preparedness and reduce aberrations. Various statistical methods and techniques are used to quantify and predict the LoS of a patient based on pre-operative clinical features. This study evaluates and compares the results of Bayesian (simple Bayesian regression and hierarchical Bayesian regression) models and machine learning (ML) regression models against multiple evaluation metrics for the problem of LoS prediction of cardiac patients admitted to Tabba Heart Institute, Karachi, Pakistan (THI) between 2015 and 2020. In addition, the study also presents the use of hierarchical Bayesian regression to account for data variability and skewness without homogenizing the data (by removing outliers). LoS estimates from the hierarchical Bayesian regression model resulted in a root mean squared error (RMSE) and mean absolute error (MAE) of 1.49 and 1.16, respectively. Simple Bayesian regression (without hierarchy) achieved an RMSE and MAE of 3.36 and 2.05, respectively. The average RMSE and MAE of ML models remained at 3.36 and 1.98, respectively.

State-of-the-art CT and MR imaging and assessment of atherosclerotic carotid artery disease: standardization of scanning protocols and measurements-a consensus document by the European Society of Cardiovascular Radiology (ESCR)

The European Society of Cardiovascular Radiology (ESCR) is the European specialist society of cardiac and vascular imaging. This society's highest priority is the continuous improvement, development, and standardization of education, training, and best medical practice, based on experience and evidence. The present intra-society consensus is based on the existing scientific evidence and on the individual experience of the members of the ESCR writing group on carotid diseases, the members of the ESCR guidelines committee, and the members of the executive committee of the ESCR. The recommendations published herein reflect the evidence-based society opinion of ESCR. We have produced a twin-papers consensus, indicated through the documents as respectively "Part I" and "Part II." The first document (Part I) begins with a discussion of features, role, indications, and evidence for CT and MR imaging-based diagnosis of carotid artery disease for risk stratification and prediction of stroke (Section I). It then provides an extensive overview and insight into imaging-derived biomarkers and their potential use in risk stratification (Section II). Finally, detailed recommendations about optimized imaging technique and imaging strategies are summarized (Section III). The second part of this consensus paper (Part II) is focused on structured reporting of carotid imaging studies with CT/MR. KEY POINTS: • CT and MR imaging-based evaluation of carotid artery disease provides essential information for risk stratification and prediction of stroke. • Imaging-derived biomarkers and their potential use in risk stratification are evolving; their correct interpretation and use in clinical practice must be well-understood. • A correct imaging strategy and scan protocol will produce the best possible results for disease evaluation.

Carotid Artery Plaque Calcifications: Lessons From Histopathology to Diagnostic Imaging

The role of calcium in atherosclerosis is controversial and the relationship between vascular calcification and plaque vulnerability is not fully understood. Although calcifications are present in ≈50% to 60% of carotid plaques, their association with cerebrovascular ischemic events remains unclear. In this review, we summarize current understanding of carotid plaque calcification. We outline the role of calcium in atherosclerotic carotid disease by analyzing laboratory studies and histopathologic studies, as well as imaging findings to understand clinical implications of carotid artery calcifications. Differences in mechanism of calcium deposition express themselves into a wide range of calcification phenotypes in carotid plaques. Some patterns, such as rim calcification, are suggestive of plaques with inflammatory activity with leakage of the vasa vasourm and intraplaque hemorrhage. Other patterns such as dense, nodular calcifications may confer greater mechanical stability to the plaque and reduce the risk of embolization for a given degree of plaque size and luminal stenosis. Various distributions and patterns of carotid plaque calcification, often influenced by the underlying systemic pathological condition, have a different role in affecting plaque stability. Modern imaging techniques afford multiple approaches to assess geometry, pattern of distribution, size, and composition of carotid artery calcifications. Future investigations with these novel technologies will further improve our understanding of carotid artery calcification and will play an important role in understanding and minimizing stroke risk in patients with carotid plaques.

Assessment of Albumin ECM Accumulation and Inflammation as Novel In Vivo Diagnostic Targets for Multi-Target MR Imaging

Atherosclerosis is a progressive inflammatory vascular disease characterized by endothelial dysfunction and plaque burden. Extracellular matrix (ECM)-associated plasma proteins play an important role in disease development. Our magnetic resonance imaging (MRI) study investigates the feasibility of using two different molecular MRI probes for the simultaneous assessment of ECM-associated intraplaque albumin deposits caused by endothelial damage and progressive inflammation in atherosclerosis. Male apolipoprotein E-deficient (ApoE^-/-)-mice were fed a high-fat diet (HFD) for 2 or 4 months. Another ApoE^-/--group was treated with pravastatin and received a HFD for 4 months. T1- and T2*-weighted MRI was performed before and after albumin-specific MRI probe (gadofosveset) administration and a macrophage-specific contrast agent (ferumoxytol). Thereafter, laser ablation inductively coupled plasma mass spectrometry and histology were performed. With advancing atherosclerosis, albumin-based MRI signal enhancement and ferumoxytol-induced signal loss areas in T2*-weighted MRI increased. Significant correlations between contrast-to-noise-ratio (CNR) post-gadofosveset and albumin stain (R² = 0.78, p < 0.05), and signal loss areas in T2*-weighted MRI with Perls' Prussian blue stain (R² = 0.83, p < 0.05) were observed. No interference of ferumoxytol with gadofosveset enhancement was detectable. Pravastatin led to decreased inflammation and intraplaque albumin. Multi-target MRI combining ferumoxytol and gadofosveset is a promising method to improve diagnosis and treatment monitoring in atherosclerosis.

The age- and sex-specific composition of atherosclerotic plaques in vascular surgery patients

BACKGROUND AND AIMS

The sex- and age-related differences in the composition of iliofemoral atherosclerotic plaques are largely unknown. Therefore, the aim of the current study is to gain insight into plaque composition across strata of age and sex in a large cohort of vascular surgery patients.

METHODS

Peripheral atherosclerotic plaques of patients who underwent iliofemoral endarterectomy (n = 790) were harvested between 2002 and 2014. The plaques were semi-quantitatively analyzed for the presence of lipid cores, calcifications, plaque hemorrhages (PH), collagen, macrophage and smooth muscle cell (SMC) content, and quantitatively for microvessel density. Patients were stratified by age tertiles and sex.

RESULTS

Ageing was independently associated with rupture-prone iliofemoral plaque characteristics, such as higher prevalence of plaque calcifications (OR 1.52 (95%CI:1.03-2.24) p = 0.035) and PH (OR 1.46 (95%CI:1.01-2.09) p = 0.042), and lower prevalence of collagen (OR 0.52 (95%CI:0.31-0.86) p = 0.012) and SMCs (OR 0.59 (95%CI:0.39-0.90) p = 0.015). Sex-stratified data showed that men had a higher prevalence of lipid cores (OR 1.62 (95%CI:1.06-2.45) p = 0.025) and PH (OR 1.62 (95%CI:1.16-2.54) p = 0.004) compared to women. These sex-differences attenuated with increasing age, with women showing an age-related increase in calcifications (p = 0.002), PH (p = 0.015) and decrease in macrophages (p = 0.005). In contrast, men only showed a decrease in collagen (p = 0.043).

CONCLUSIONS

Atherosclerotic iliofemoral plaques derived from men display more rupture-prone characteristics compared to women. Yet, this difference is attenuated with an increase in age, with older women having more rupture-prone characteristics compared to younger women.

The Role of Vascular Aging in Atherosclerotic Plaque Development and Vulnerability

BACKGROUND

The ongoing demographical shift is leading to an unprecedented aging of the population. As a consequence, the prevalence of age-related diseases, such as atherosclerosis and its thrombotic complications is set to increase in the near future. Endothelial dysfunction and vascular stiffening characterize arterial aging and set the stage for the development of cardiovascular diseases. Atherosclerotic plaques evolve over time, the extent to which these changes might affect their stability and predispose to sudden complications remains to be determined. Recent advances in imaging technology will allow for longitudinal prospective studies following the progression of plaque burden aimed at better characterizing changes over time associated with plaque stability or rupture. Oxidative stress and inflammation, firmly established driving forces of age-related CV dysfunction, also play an important role in atherosclerotic plaque destabilization and rupture. Several genes involved in lifespan determination are known regulator of redox cellular balance and pre-clinical evidence underlines their pathophysiological roles in age-related cardiovascular dysfunction and atherosclerosis.

OBJECTIVE

The aim of this narrative review is to examine the impact of aging on arterial function and atherosclerotic plaque development. Furthermore, we report how molecular mechanisms of vascular aging might regulate age-related plaque modifications and how this may help to identify novel therapeutic targets to attenuate the increased risk of CV disease in elderly people.

Patient risk factors associated with embolic stroke volumes after revascularization

OBJECTIVE

Previous research has shown that subclinical, microembolic infarcts result in long-term cognitive changes. Whereas both carotid endarterectomy (CEA) and carotid artery stenting (CAS) have potential for microembolic events, CAS has been shown to have a larger volume of infarct. We have previously shown that large-volume infarction is associated with long-term memory deterioration. The purpose of this study was to identify independent risk factors that trend toward higher embolic volumes in both procedures.

METHODS

A total of 162 patients who underwent carotid revascularization procedures were prospectively recruited at two separate institutions. Preoperative and postoperative brain magnetic resonance images were compared to identify procedure-related microinfarcts. A novel semiautomated approach was used to define volumes of infarcts for each patient. Patient-related factors including comorbidities, symptomatic status, and medications were analyzed. Tweedie regression analysis was used to identify risk factors associated with procedure-related infarct volume. Variables with an unadjusted P value of ≤ .05 were included in the multivariate analysis.

RESULTS

There were 80 CAS and 82 CEA procedures performed and analyzed for the data set; 81% of CAS patients had procedure-related new infarcts with a mean volume of 388.15 ± 927.90 mm³ compared with 30% of CEA patients with a mean volume of 74.80 ± 225.52 mm³. In the CAS cohort, increasing age (adjusted coefficient ± standard error, 0.06 ± 0.02; P < .01) and obesity (1.14 ± 0.35; P < .01) were positively correlated with infarct volume, whereas antiplatelet use (-1.11 ± 0.33; P < .001) was negatively correlated with infarct volume. For the CEA group, diabetes (adjusted coefficient ± standard error, 1.69 ± 0.65; P < .01) was identified as the only risk factor positively correlated with infarct volume, whereas increasing age (-0.10 ± 0.05; P = .03) was negatively correlated with infarct volume.

CONCLUSIONS

Risk factors for CAS- or CEA-related infarct volumes are identified in our study. Although the result warrants further validation, this study showed that advanced age, obesity, and diabetes independently predicted volume of microinfarcts related to CAS and CEA. These data provide valuable information for patient factor-based risk stratification and preoperative consultation for each procedure.

Carotid Disease and Ageing: A Literature Review on the Pathogenesis of Vascular Senescence in Older Subjects

Aging is a natural process that affects all systems of the human organism, leading to its inability to adapt to environmental changes. Advancing age has been correlated with various pathological conditions, especially cardiovascular and cerebrovascular diseases. Carotid artery (CA) is mainly affected by age-induced functional and morphological alterations causing atheromatous disease. The evolvement of biomedical sciences has allowed the elucidation of many aspects of this condition. Symptomatic carotid disease (CD) derives from critical luminar stenosis or eruption of an atheromatous plaque due to structural modifications of the vessels, such as carotid intima-media thickening. At a histologic level, the aforementioned changes are mediated by elastin fragmentation, collagen deposition, immune cell infiltration, and accumulation of cytokines and vasoconstrictors. Underlying mechanisms include chronic inflammation and oxidative stress, dysregulation of cellular homeostatic systems, and senescence. Thus, there is an imbalance in components of the vessel wall, which fails to counteract exterior stress stimuli. Consequently, arterial relaxation is impaired and atherosclerotic lesions progress. This is a review of current evidence regarding the relationship of aging with vascular senescence and CD. A deeper understanding of these mechanisms can contribute to the production of efficient prevention methods and targeted therapeutic strategies.

Immune cells in carotid artery plaques: what can we learn from endarterectomy specimens?

INTRODUCTION

Endarterectomy specimens represent a unique opportunity to study atherosclerosis. This review aims to summarize the recent knowledge of atherogenesis from studies characterizing a cellular composition of carotid endarterectomy specimens.

EVIDENCE ACQUISITION

A non-systematic literature review was carried out to summarize recent knowledge regarding ex vivo analysis of carotid artery plaque composition. Upon evaluation of their relevance, and elaborate forward and backward search, 95 articles were included in the review.

EVIDENCE SYNTHESIS

Despite the significant advancement of in vivo imaging techniques, the stroke prediction based on carotid artery plaque morphology is not reliable. Besides analyses of plaque morphology, present studies focus on precise characterization of the different immune cell types and elucidation of their role in plaque development. Plaque content analyses revealed the presence of various immune cells in carotid artery plaques. Presence of different immune cells subpopulations can be connected to some undesirable changes in plaque stability.

CONCLUSIONS

Since the destabilization of the atherosclerotic plaque is a multifactorial process, a combination of various methods should be used to characterize the unstable plaques more accurately. In this context, studies characterizing plaque content from a cellular point of view could elucidate some processes underlying the plaque progression. Together with morphological evaluation, these analyses could enable more precise assessment of plaque stability.

Ranking of stroke and cardiovascular risk factors for an optimal risk calculator design: Logistic regression approach

PURPOSE

Conventional cardiovascular risk factors (CCVRFs) and carotid ultrasound image-based phenotypes (CUSIP) are independently associated with long-term risk of cardiovascular (CV) disease. In this study, 26 cardiovascular risk (CVR) factors which consisted of a combination of CCVRFs and CUSIP together were ranked. Further, an optimal risk calculator using AtheroEdge composite risk score (AECRS1.0) was designed and benchmarked against seven conventional CV risk (CVR) calculators.

METHODS

Two types of ranking were performed: (i) ranking of 26 CVR factors and (ii) ranking of eight types of 10-year risk calculators. In the first case, multivariate logistic regression was used to compute the odds ratio (OR) and in the second, receiver operating characteristic curves were used to evaluate the performance of eight types of CVR calculators using SPSS23.0 and MEDCALC12.0 with validation against STATA15.0.

RESULTS

The left and right common carotid arteries (CCA) of 202 Japanese patients were examined to obtain 404 ultrasound scans. CUSIP ranked in the top 50% of the 26 covariates. Intima-media thickness variability (IMTV) and IMTV_10yr were the most influential carotid phenotypes for left CCA (OR = 250, P < 0.0001 and OR = 207, P < 0.0001 respectively) and right CCA (OR = 1614, P < 0.0001 and OR = 626, P < 0.0001 respectively). However, for the mean CCA, AECRS1.0 and AECRS1.0_10yr reported the most highly significant OR among all the CVR factors (OR = 1.073, P < 0.0001 and OR = 1.104, P < 0.0001). AECRS1.0_10yr also reported highest area-under-the-curve (AUC = 0.904, P < 0.0001) compared to seven types of conventional calculators. Age and glycated haemoglobin reported highest OR (1.96, P < 0.0001 and 1.05, P = 0.012) among all other CCVRFs.

CONCLUSION

AECRS1.0_10yr demonstrated the best performance due to presence of CUSIP and ranked at the first place with highest AUC.

Pathology of Peripheral Artery Disease in Patients With Critical Limb Ischemia

BACKGROUND

Critical limb ischemia (CLI) is the most serious complication of peripheral artery disease (PAD).

OBJECTIVES

The purpose of this study was to characterize pathology of PAD in below- and above-knee amputation specimens in patients presenting with CLI.

METHODS

Peripheral arteries from 95 patients (121 amputation specimens) were examined; 75 patients had presented with CLI, and the remaining 20 had amputations performed for other reasons. The pathological characteristics were separately recorded for femoral and popliteal arteries (FEM-POP), and infrapopliteal arteries (INFRA-POP).

RESULTS

A total of 299 arteries were examined. In the 239 arteries from CLI patients, atherosclerotic plaques were more frequent in FEM-POP (23 of 34, 67.6%) compared with INFRA-POP (79 of 205, 38.5%) arteries. Of these 239 arteries, 165 (69%) showed ≥70% stenosis, which was due to significant pathological intimal thickening, fibroatheroma, fibrocalcific lesions, or restenosis in 45 of 165 (27.3%), or was due to luminal thrombi with (39 of 165, 23.6%) or without (81 of 165, 49.1%) significant atherosclerotic lesions. Presence of chronic luminal thrombi was more frequently observed in arteries with insignificant atherosclerosis (OR: 16.7; p = 0.0002), more so in INFRA-POP compared with FEM-POP (OR: 2.14; p = 0.0041) arteries. Acute thrombotic occlusion was less frequently encountered in INFRA-POP than FEM-POP arteries (OR: 0.27; p = 0.0067). Medial calcification was present in 170 of 239 (71.1%) large arteries.

CONCLUSIONS

Thrombotic luminal occlusion associated with insignificant atherosclerosis is commonly observed in CLI and suggests the possibility of atherothromboembolic disease. The pathological characteristics of arteries in CLI suggest possible mechanisms of progression of PAD to CLI, especially in INFRA-POP arteries, and may support the preventive role of antithrombotic agents.

Receptor activator of NF-κB ligand (RANKL) increases the release of neutrophil products associated with coronary vulnerability

The “blood vulnerability”, resulting from the complex balance between serum molecules and inflammatory cell atherosclerotic activities, is a major determinant in the evaluation of the “global patient cardiovascular vulnerability”. In the present study, we focused on the role of the soluble receptor activator of nuclear factor kappa-B (NF-κB) ligand (RANKL, a potential marker of coronary calcification and vulnerability) in the release of neutrophilic proteases. Then, the association between these mediators and the degree of coronary calcification (assessed by coronary calcium score [CCS]) was investigated in 20 subjects (aged ≥65 years) asymptomatic for cardiovascular disease. Results showed that RANKL dose-dependently induced matrix metalloprotease (MMP)-8 and MMP-9 release from human primary neutrophils cultured in Teflon dishes (suspension condition, mimicking cells circulating in the blood stream). Conversely, when adherent to polystyrene, neutrophils became unresponsive to RANKL. RANKL did not influence the release of other neutrophilic products in suspension and adherence cultures as well as neutrophil migration. RANKL-induced release of MMPs was dependent on the activation of defined intracellular signalling pathways (PI3K/Akt and ERK1/2). In asymptomatic subjects, serum levels of RANKL, MMP-8 and MMP-9 positively correlated with CCS, reflecting a potential relationship between circulating RANKL and coronary calcification. In conclusion, RANKL increased the release of neutrophilic products potentially related to the “blood” vulnerability via defined intracellular pathways. Serum levels of RANKL might represent a potential biomarker of coronary calcification and related cardiovascular risk.

Long non-coding RNAs in the atherosclerotic plaque

BACKGROUND AND AIMS

Genetic and environmental factors are important components of the development of atherosclerosis. Long non-coding RNA (lncRNAs) have emerged as regulators of multiple pathophysiological pathways in the cardiovascular system. Here, we investigated potential associations between lncRNAs and atherosclerosis.

METHODS

Tissue samples from atherosclerotic coronary artery plaques and non-atherosclerotic internal mammary artery were obtained from 20 patients during coronary artery bypass surgery. Expression levels of five lncRNAs known to be associated with coronary artery disease were measured using quantitative PCR.

RESULTS

Cyclin-dependent kinase inhibitor 2B antisense RNA 1 (ANRIL) and myocardial infarction-associated transcript (MIAT) were more expressed in the atherosclerotic arteries compared to the non-atherosclerotic arteries. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was less expressed in the atherosclerotic plaques. Expression levels of potassium voltage-gated channel, KQT-like subfamily, member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) and hypoxia inducible factor 1A antisense RNA 2 (aHIF) were comparable between atherosclerotic and non-atherosclerotic arteries. In the atherosclerotic plaque, expression levels of MALAT1, MIAT, KCNQ1OT1 and aHIF were inversely correlated with age.

CONCLUSIONS

We report significant associations between lncRNAs and atherosclerosis. These findings support a role for lncRNAs in coronary artery disease development.

Age and composite end-point events in medium follow-up of patients with carotid artery total occlusion using drug therapy

BACKGROUND AND AIMS

The outcome of carotid artery total occlusion (CATO) is unclear. The aim of this study is to report the medium incidence of composite end-point events and risk factors (especially age), in patients with CATO, treated medically.

METHODS

This was a single center retrospective study. Composite end-point events included death, ischemic stroke, transient ischemic attack, hemorrhagic stroke, myocardial infarction, or angina. Logistic regression analysis was used to analyze risk factors of composite end-point events.

RESULTS

A total of 94 patients with CATO were included in the study. The mean follow-up duration was 30 ± 16 months. There were 16 cases who experienced composite end-point events (17.0%); among them, there were 15 cases of death (16.0%), 8 cases of ischemic stroke (7 cases of fatal stroke and 1 case of non-fatal stroke) (8.5%), and 1 case of angina pectoris (1%) (the patient later developed ischemic stroke). With increased age, the incidence of composite end-point events was significantly increased (p = 0.002). Multivariate logistic regression analysis showed that only age was a risk factor (OR = 3.051 (1.351-6.890), p = 0.007).

CONCLUSIONS

The incidence of composite end-point events in patients with CATO was as high as 17.0% at approximately 3 years after drug therapy alone. For every 10 years of age increase, the risk increase of composite end-point events doubles.

Arterial ageing: from endothelial dysfunction to vascular calcification

Complex structural and functional changes occur in the arterial system with advancing age. The aged artery is characterized by changes in microRNA expression patterns, autophagy, smooth muscle cell migration and proliferation, and arterial calcification with progressively increased mechanical vessel rigidity and stiffness. With age the vascular smooth muscle cells modify their phenotype from contractile to 'synthetic' determining the development of intimal thickening as early as the second decade of life as an adaptive response to forces acting on the arterial wall. The increased permeability observed in intimal thickening could represent the substrate on which low-level atherosclerotic stimuli can promote the development of advanced atherosclerotic lesions. In elderly patients the atherosclerotic plaques tend to be larger with increased vascular stenosis. In these plaques there is a progressive accumulation of both lipids and collagen and a decrease of inflammation. Similarly the plaques from elderly patients show more calcification as compared with those from younger patients. The coronary artery calcium score is a well-established marker of adverse cardiovascular outcomes. The presence of diffuse calcification in a severely stenotic segment probably induces changes in mechanical properties and shear stress of the arterial wall favouring the rupture of a vulnerable lesion in a less stenotic adjacent segment. Oxidative stress and inflammation appear to be the two primary pathological mechanisms of ageing-related endothelial dysfunction even in the absence of clinical disease. Arterial ageing is no longer considered an inexorable process. Only a better understanding of the link between ageing and vascular dysfunction can lead to significant advances in both preventative and therapeutic treatments with the aim that in the future vascular ageing may be halted or even reversed.

Patients with gout have short telomeres compared with healthy participants: association of telomere length with flare frequency and cardiovascular disease in gout

AIM AND BACKGROUND

Chronic inflammation associates with increased senescence, which is a strong predictor for cardiovascular disease. We hypothesised that inflammation accelerates senescence and thereby enhances the risk of cardiovascular disease in gout.

METHODS

We assessed replicative senescence by quantifying telomere length (TL) in a discovery cohort of 145 Dutch patients with gout and 273 healthy individuals and validated our results in 474 patients with gout and 293 healthy participants from New Zealand. Subsequently, we investigated the effect of cardiovascular disease on TL of all participants. Also, we measured TL of CD4⁺ and CD8⁺ T lymphocytes, B lymphocytes, monocytes, natural killer cells and plasmacytoid dendritic cells. Additionally, we assessed the potential temporal difference in TL and telomerase activity.

RESULTS

TL in PBMCs of healthy donors decreased over time, reflecting normal ageing. Patients with gout demonstrated shorter telomeres (p=0.001, R²=0.01873). In fact, the extent of telomere erosion in patients with gout was higher at any age compared with healthy counterparts at any age (p<0.0001, R²=0.02847). Patients with gout with cardiovascular disease had the shortest telomeres and TL was an independent risk factor for cardiovascular disease in patients with gout (p=0.001). TL was inversely associated with the number of gouty flares (p=0.005).

CONCLUSIONS

Patients with gout have shorter telomeres than healthy participants, reflecting increased cellular senescence. Telomere shortening was associated with the number of flares and with cardiovascular disease in people with gout.

Age-associated changes in human carotid atherosclerotic plaques

Little is known about changes in carotid plaque morphology during aging and the possible impact on cardiovascular events. Only few studies addressed so far age-related modifications within atherosclerotic lesions. Therefore, in this work we endeavored to summarize the current knowledge about changing of plaque composition in elderly. The data from hitherto existing studies confirm that atherosclerotic plaques undergo distinct alternations with advanced age. However, the results are often ambiguous and the changes do not seem to be as disastrous as expected. Interestingly, none of the studies could definitely evidence increased plaque vulnerability with advanced age. Nevertheless, based on the previous work showing decrease in elastin fibers, fibroatheroma, SMCs, overall cellularity and increase in the area of lipid core, hemorrhage, and calcification, the plaque morphology appears to transform toward unstable plaques. Otherwise, even if inflammatory cells often accumulate in plaques of younger patients, their amount is reduced in the older age and so far no clear association has been observed between thin fibrous cap and aging. Thus, the accurate contribution of age-related changes in plaque morphology to cardiovascular events has yet to be elucidated. KEY MESSAGES Composition of carotid atherosclerotic lesions changes during aging. These alternations are however, just moderate and depend upon additional variables, such as life style, accompanying disease, genetics, and other factors that have yet to be determined. Based on the current data, the age-associated plaque morphology seems to transform toward vulnerable plaques. However, the changes do not seem to be as disastrous as expected.

Histomorphological evaluation of atherosclerotic lesions in patients with peripheral artery occlusive disease

PURPOSE

Peripheral arterial occlusive disease (PAOD) is mainly caused by atherosclerosis of the vessel wall. These pathological changes are classified into different stages and are well described for carotid and coronary vessels, but not for PAOD. The aim of our study was to analyze plaque morphology of femoral arteries in patients with intermittent claudication and critical limb ischemia.

PATIENTS AND METHODS

In this retrospective study 85 atherosclerotic plaques (common and superficial femoral artery) of 71 patients with a clinical symptomatic PAOD were analyzed, by histology (01/2009-07/2010). Atherosclerotic lesions were classified according to Stary (type I-VIII). For further characterization, plaques were evaluated for the presence of collagen, elastin, calcifications, smooth muscle cells, macrophages, leucocytes, and cellularity.

RESULTS

The majority (91%) of atherosclerotic lesions were of advanced types according to Stary (V-VII). Atherosclerotic lesion type VI was associated with significant higher amount of inflammatory cells in comparison to all other atherosclerotic plaque types (CD45: p<0.001; CD68: p=0.013). In addition, atherosclerotic plaques with a pronounced neovascularization contained a higher amount of CD45 (p=0.015; rho=0.273) and CD68 (p=0.016; rho=0.275) positive cells.

CONCLUSION

Atherosclerotic lesions of femoral arteries show similar morphological changes as coronary or carotid arteries. But inflammatory cells had a higher impact on plaque progression and destabilization than any other factor.

Age-associated pro-inflammatory remodeling and functional phenotype in the heart and large arteries

The aging population is increasing dramatically. Aging–associated stress simultaneously drives proinflammatory remodeling, involving angiotensin II and other factors, in both the heart and large arteries. The structural remodeling and functional changes that occur with aging include cardiac and vascular wall stiffening, systolic hypertension and suboptimal ventricular-arterial coupling, features that are often clinically silent and thus termed a silent syndrome. These age-related effects are the result of responses initiated by cardiovascular proinflammatory cells. Local proinflammatory signals are coupled between the heart and arteries due to common mechanical and humoral messengers within a closed circulating system. Thus, targeting proinflammatory signaling molecules would be a promising approach to improve age-associated suboptimal ventricular-arterial coupling, a major predisposing factor for the pathogenesis of clinical cardiovascular events such as heart failure.

Low levels of IgM antibodies against phosphorylcholine are associated with fast carotid intima media thickness progression and cardiovascular risk in men

OBJECTIVE

Low levels of IgM anti-phosphorylcholine (anti-PC) increase the risk of cardiovascular events (CVE). Here we investigate the association of low anti-PC with the progression of carotid intima media thickness (C-IMT) and incidence of CVE in a large cohort of individuals at high risk of CVE, the IMPROVE, a prospective multicenter European study.

METHODS

3711 subjects (54-79 years) with at least three established cardiovascular risk factors were enrolled. Baseline serum levels of IgM anti-PC were measured by ELISA. Carotid ultrasound investigations were performed at baseline and after 15 and 30 months of follow-up. The risk of C-IMT progression and ischemic CVE associated with low anti-PC levels was tested by logistic regression and Cox regression analysis, respectively. Risk estimates were adjusted by center and conventional cardiovascular risk factors.

RESULTS

3670 study participants were included in the present analysis and 213 CVE were recorded during a 3 year follow up. Anti-PC levels (U/ml) were classified into quartiles [Q1≤ 40, Q2 >40-≤64, Q3 >64-≤102, Q4 >102]. In men, low levels of anti-PC (Q1) were associated with the highest (>90th) percentile of the fastest C-IMT progression, i.e. the segment showing the fastest progression over 30 months in the whole carotid tree, with an OR of 1.41 (95%CI, 1.02-1.9) and with an increased risk of CVE with a multivariable adjusted HR of 1.85 (95%CI, 1.1-3.1). No significant associations were found in women.

CONCLUSIONS

Low anti-PC levels increase the risk of CVE in men. This effect may be partly mediated by a fast C-IMT progression.

Attenuated predictive power of a normal myocardial perfusion scan in young smokers

BACKGROUND

The negative predictive value of a normal myocardial perfusion image (MPI) for myocardial infarction or cardiac death is very high. However, it is unclear whether a normal MPI, reflecting non-compromised blood flow in the stable state, would have the same prognostic implications in smokers as in patients who do not smoke.

METHODS

The incidence of total mortality, cardiovascular mortality, and myocardial infarction was evaluated in 11,812 subjects (14.6% of whom were current smokers at the time of the study) with a normal MPI study and no past history of coronary artery disease during the period 1997 to 2008.

RESULTS

During an average follow-up of 72.4 ± 32.4 months the risk for an acute myocardial infarction in current smokers was approximately 50% higher than the corresponding risk in non-smokers, despite a younger average age. Cox proportional regression models show that current smoking was associated with an increased hazard rate for the composite endpoint below age 60 (HR=2.09, 95%CI 1.43-3.07, p<0.001), but not at older ages (HR=1.16, 95% CI 0.81-1.66, p=0.4).

CONCLUSIONS

In individuals below age 60, but not at older ages, current smoking is associated with increased short- and long-term risk of cardiac death and acute myocardial infarction even in subjects with a normal MPI.

10-years experience with the Athero-Express study

From cross-sectional studies we have learned that composition of atherosclerotic plaques differs, and that thrombosis on top of an inflammatory lipid rich plaque is a frequently observed pathological substrate of a cerebral or coronary event. Atherosclerosis develops over decades which hampers human studies on the natural history of the diseases. Therefore, the predictive value of atherosclerotic plaque composition for development of an adverse cardiovascular event is not clear. The elucidation of markers for atherosclerotic disease progression is essential to identify patients at high risk for vascular events, to refine treatment allocation and to serve as surrogate endpoints in pharmaceutical studies. The Athero-Express study is a large scale vascular biobank that collects vascular specimens including a clinical follow-up. This study design allows the prospective study of the local atherosclerotic plaque in relation to future local and systemic vascular outcome. The readout of the study can be assessed in terms of histology as well as RNA or protein level. This paper aims to give an overview of the results of the Athero-Express biobank since its initiation in 2002. We will also discuss the clinical implications and future directions in biobanking research.

Dual-energy computed tomography imaging of atherosclerotic plaques in a mouse model using a liposomal-iodine nanoparticle contrast agent

BACKGROUND

The accumulation of macrophages in inflamed atherosclerotic plaques has long been recognized. In an attempt to develop an imaging agent for detection of vulnerable plaques, we evaluated the feasibility of a liposomal-iodine nanoparticle contrast agent for computed tomography imaging of macrophage-rich atherosclerotic plaques in a mouse model.

METHODS AND RESULTS

Liposomal-iodine formulations varying in particle size and polyethylene glycol coating were fabricated and shown to stably encapsulate the iodine compound. In vitro uptake studies using optical and computed tomography imaging in the RAW 264.7 macrophage cell line identified the formulation that promoted maximal uptake. Dual-energy computed tomography imaging using this formulation in apolipoprotein E-deficient (ApoE(-/-)) mice (n=8) and control C57BL/6 mice (n=6) followed by spectral decomposition of the dual-energy images enabled imaging of the liposomes localized in the plaque. Imaging cytometry confirmed the presence of liposomes in the plaque and their colocalization with a small fraction (≈2%) of the macrophages in the plaque.

CONCLUSIONS

The results demonstrate the feasibility of imaging macrophage-rich atherosclerotic plaques using a liposomal-iodine nanoparticle contrast agent and dual-energy computed tomography.

Associations of CXCL16/CXCR6 with carotid atherosclerosis in patients with metabolic syndrome

BACKGROUND & AIMS

Chemokine CXC ligand 16 (CXCL16) has chemokine, adhesion molecule and scavenger receptor functions involving the immune function. Atherosclerosis is an inflammatory disease. We aimed to study the association of chemokine CXCL16/CXCR6 and carotid atherosclerosis in patients with metabolic syndrome.

METHODS

Carotid ultrasonography was determined in 30 patients with metabolic syndrome and 30 controls. The mRNA levels of CXCL6/CXCR6 were detected by real-time RT-PCR. The activation of T cells and expression of CXCR6 in T lymphocyte cells and natural killer T (NKT) cells was detected by flow cytometry. The serum level of sol-CXCL6 was determined by ELISA.

RESULTS

Compared with controls, patients with metabolic syndrome showed significantly increased waist circumference and levels of total cholesterol, triglycerides and low-density lipoprotein cholesterol (all P < 0.001), with increased abnormalities of the structure and function of the carotid artery (P < 0.05). In metabolic syndrome, the levels of sol-CXCL16 and CXCL16mRNA were increased and associated with max IMT and plaque index. Patients with metabolic syndrome showed increased number of CXCR6+ T cells and CXCR6+ NKT cells, which was associated with max IMT and plaque index.

CONCLUSIONS

CXCL16 and CXCR6 may be associated the formation of carotid atherosclerotic plaque in metabolic syndrome, and T cells may be the important effector cells in the pathogenesis of the atherosclerosis.

PLACD-7T Study: Atherosclerotic Carotid Plaque Components Correlated with Cerebral Damage at 7 Tesla Magnetic Resonance Imaging

Introduction:

In patients with carotid artery stenosis histological plaque composition is associated with plaque stability and with presenting symptomatology. Preferentially, plaque vulnerability should be taken into account in pre-operative work-up of patients with severe carotid artery stenosis. However, currently no appropriate and conclusive (non-) invasive technique to differentiate between the high and low risk carotid artery plaque in vivo is available. We propose that 7 Tesla human high resolution MRI scanning will visualize carotid plaque characteristics more precisely and will enable correlation of these specific components with cerebral damage.

Study objective:

The aim of the PlaCD-7T study is 1: to correlate 7T imaging with carotid plaque histology (gold standard); and 2: to correlate plaque characteristics with cerebral damage ((clinically silent) cerebral (micro) infarcts or bleeds) on 7 Tesla high resolution (HR) MRI.

Design:

We propose a single center prospective study for either symptomatic or asymptomatic patients with haemodynamic significant (70%) stenosis of at least one of the carotid arteries. The Athero-Express (AE) biobank histological analysis will be derived according to standard protocol. Patients included in the AE and our prospective study will undergo a pre-operative 7 Tesla HR-MRI scan of both the head and neck area.

Discussion:

We hypothesize that the 7 Tesla MRI scanner will allow early identification of high risk carotid plaques being associated with micro infarcted cerebral areas, and will thus be able to identify patients with a high risk of periprocedural stroke, by identification of surrogate measures of increased cardiovascular risk.

Is age of 80 years a threshold for carotid revascularization?

Background and purpose:

Carotid Angioplasty and Stenting (CAS) has emerged as an alternative to Carotid Endarterectomy (CEA) in treatment of carotid stenotic disease. With increasing life expectancy clinicians are more often confronted with patients of higher age. Octogenarians were often excluded from randomized trials comparing CAS to CEA because they were considered high-risk for revascularization. Conflicting results on the peri-procedural outcome of carotid revascularization in these patients have been reported. In order to objectively evaluate whether age above 80 years should be an upper limit for indicating carotid revascularization we systematically reviewed the currently available literature.

Methods:

Literature was systematically reviewed between January 2000 and June 2010 using Pubmed and Embase, to identify all relevant studies concerning CAS and CEA in octogenarians. Inclusion criteria were 1) reporting outcome on either CEA or CAS; and 2) data subanalysis on treatment outcome by age. The 30-day Major Adverse Event (MAE) rate (disabling stroke, myocardial infarction or death) was extracted as well as demographic features of included patients.

Results:

After exclusion of 23 articles, 46 studies were included in this review, 18 involving CAS and 28 involving CEA. A total of 2.963 CAS patients and 14.365 CEA patients with an age >80 years were reviewed. The MAE rate was 6.9% (range 1.6 - 24.0%) following CAS and 4.2% (range 0 – 8.8%) following CEA.

A separate analysis in this review included the results of one major registry 140.376 patients) analyzing CEA in octogenarians only reporting on 30-day mortality and not on neurological or cardiac adverse events. When these data were included the MAE following CEA is 2.4% (range 0 – 8.8%)

Conclusions:

MAE rates after CEA in octogenarians are comparable with the results of large randomized trials in younger patients. Higher complication rates are described for CAS in octogenarians. In general, age > 80 years is not an absolute cut off point to exclude patients from carotid surgery. In our opinion, CEA should remain the golden standard in the treatment of significant carotid artery stenoses, even in the very elderly.

Dyslipidemia: evidence of efficacy of the pharmacological and non-pharmacological treatment in the elderly

The clinical decision to control risk factors for cardiovascular disease (CVD) in the elderly takes the followings into consideration: (1) the elderly life expectancy; (2) the elderly biological age and functional capacity; (3) the role of cardiovascular disease in the elderly group; (4) the prevalence of risk factors in the elderly; and (5) The effectiveness of treatment of risk factors in the elderly. A large number of studies showed the efficacy of secondary and primary prevention of dyslipidemia in the elderly. However, the only trial that included patients over 80 years was the Heart Protection Study (HPS). Statins are considered the first line therapy for lowering low-density lipoprotein cholesterol (LDL-C). Because lifestyle changes are very difficult to achieve, doctors in general tend to prescribe many drugs to control cardiovascular risk factors. However, healthy food consumption remains a cornerstone in primary and secondary cardiovascular prevention and should be implemented by everyone.

Microvascular endoglin (CD105) expression correlates with tissue markers for atherosclerotic plaque vulnerability in an ageing population with multivessel coronary artery disease

AIMS

Vulnerable atherosclerotic plaques are lesions with a high propensity to develop plaque disruption and superimposed thrombosis. No systematic studies have been carried out on tissue markers for plaque vulnerability throughout the entire coronary artery system at the end stages of coronary atherosclerosis.

METHODS AND RESULTS

Nine autopsied patients (mean age 77 years) with angiographically severe trivascular coronary atherosclerosis were selected for this study. All visible lesions in postmortem coronary angiograms (n = 125) were histologically and immunohistochemically screened for the presence of intraplaque haemorrhages (activated) microvessels and inflammatory infiltrates. Intraplaque haemorrhages were observed in 76/125 plaques (61%). Chronic inflammation was found superficially in 59/125 plaques (47%) and deeply inside the plaque tissue in 103/125 plaques (83%). Microvessels were found in 100/125 lesions (80%), of which 58% showed endothelial expression of the vascular activation marker CD105. Moreover, microvascular CD105 positivity correlated positively with plaque haemorrhage and deeply seated plaque inflammation.

CONCLUSIONS

Plaque inflammation and haemorrhages can be found at a high frequency throughout the coronary artery system of elderly patients with multivessel coronary atherosclerosis. Microvascular expression of endoglin (CD105), which correlates positively with both of these features of plaque vulnerability, can serve as a marker of the risk of developing coronary thrombotic complications.

Impact of chronic kidney disease on carotid plaque vulnerability

OBJECTIVE

Little is known about the effect of chronic kidney disease (CKD) on plaque morphology in cerebral vessels. We therefore analyzed plaque composition and metabolic and chemical parameters with regard to clinical outcome in patients with advanced carotid artery stenosis (>70%) and normal or impaired renal function.

METHODS

Carotid endarterectomy plaques were collected from 114 patients, 51 with CKD and 63 without CKD (mean estimated glomerular filtration rate, 49 ± 9 vs 88 ± 14 mL/min), and analyzed by histology and immunohistochemistry. Serum levels of matrix metalloproteinases (MMP-1, -2, -3, -7, -8, and -9), calcium, phosphate, parathyroid hormone, fetuin-A, osteoprotegerin, and inflammatory factors, including fibrinogen, and high-sensitive C-reactive protein (hsCRP) were measured by appropriate enzyme-linked immunosorbent assay.

RESULTS

Compared with patients without CKD, patients with CKD had significantly more early-stage (11.2% vs 2.8%, P = .002) and end-stage (7.4% vs 0.2%, P = .036) calcification, unstable (50.8% vs 20.4%, P = .001) and ruptured (53.1% vs 32.8%, P = .035) lesions, and a significantly lower amount of collagenous fibers (39.2% vs 54.6%, P = .001). Serum samples of CKD patients had significantly enhanced levels of fibrinogen (393 ± 88 vs 331 ± 60 mg/dL, P = .018), hsCRP (1.7 ± 2.9 vs 0.8 ± 0.9 mg/dL; P = .042), parathyroid hormone (47.3 ± 24.1 vs 32.8 ± 12.2 ng/L, P = .010), fetuin-A (0.21 ± 0.05 vs 0.18 ± 0.04 mg/mL, P = .039), and MMP-7 (13.0 ± 5.3 vs 8.3 ± 3.0 ng/mL; P < 0.001). The incidence of cerebrovascular events >6 months before carotid surgery was significantly increased in CKD patients (84.0% vs 26.2% P < .001).

CONCLUSIONS

In patients with CKD and advanced carotid artery stenosis, morphologic changes in plaque composition may contribute to plaque vulnerability and consequently to the risk of cerebrovascular events. Furthermore, relevant serum markers of inflammation, vascular calcification, and vessel wall degradation might be an indication of stroke risk in CKD patients.

Atherosclerotic plaque vulnerability as an explanation for the increased risk of stroke in elderly undergoing carotid artery stenting

BACKGROUND AND PURPOSE

Recent randomized trials showed an increased periprocedural risk for stroke with increasing age in patients undergoing carotid artery stenting. Manipulation of atherosclerotic plaques during carotid artery stenting can result in plaque rupture with subsequent superimposed thrombus formation, embolization, and cerebrovascular events. We hypothesized that atherosclerotic plaques become more unstable with increasing age and thereby might provide insight into the age-related increased risk of cerebrovascular events during carotid artery stenting.

METHODS

Carotid atherosclerotic plaques were harvested from 1385 consecutive patients undergoing carotid endarterectomy between 2002 and 2010. Carotid plaques were quantitatively analyzed for macrophages, smooth muscle cells, and microvessels; and semiquantitatively analyzed for collagen, calcifications lipid cores, and intraplaque hemorrhages. Patients were divided in 4 groups by age: <60, 60 to 69, 70 to 79, and ≥80 years. Measures of association between age as a continuous variable and histological characteristics were also calculated.

RESULTS

Increasing age was associated with a decrease in the amount of smooth muscle cells in the carotid plaque. More plaques with large atheroma and heavy plaque calcifications were observed among elderly patients. After correction for baseline differences, risk factors, and medication use, age was independently associated with a more vulnerable carotid plaque composition.

CONCLUSIONS

Plaque stability decreases gradually with age. Older patients with carotid stenosis have relatively unstable plaques with low smooth muscle cell content, a high amount of large lipid cores, and more calcified plaques as compared with younger patients. The underlying vulnerable plaque composition in the elderly might be an important contributing factor to the increased risk of stroke for older patients undergoing carotid artery stenting.

Plaque rupture is a determinant of vascular events in carotid artery atherosclerotic disease: involvement of matrix metalloproteinases 2 and 9

BACKGROUND AND PURPOSE

Unstable carotid atherosclerotic plaques are characterized by cap rupture, leading to thromboembolism and stroke. Matrix metalloproteinases (MMPs) have been implicated in the progression of atherosclerosis and plaque rupture. The aim of this study was to assess the relationship between the expressions of MMP-2 and MMP-9 and carotid plaque instability.

METHODS

Eighty atherosclerotic plaques were collected from 74 patients undergoing carotid endarterectomy. Clinical information was obtained from each patient, and plaque morphology was examined at the macroscopic and microscopic levels. The immunohistochemical expressions of MMPs were graded using semiquantitative scales.

RESULTS

Macroscopic ulceration (84.6% versus 63.4%, p=0.042) and microscopic cap rupture (79.5% versus 51.2%, p=0.010) were more common in symptomatic than in asymptomatic patients. Immunoreactivities of MMP-2 and MMP-9 were increased in 40 and 36 atheromatous plaques, respectively. Macroscopic ulceration was strongly correlated with the expressions of MMP-2 (p<0.001) and MMP-9 (p=0.001). There were significant correlations between increased MMP-2 expression and cap rupture (p=0.002), intraplaque hemorrhage (p=0.039), and a thin fibrous cap (p=0.002), and between increased MMP-9 expression and cap rupture (p=0.010) and a large lipid core (p=0.013).

CONCLUSIONS

Plaque rupture was significantly associated with the development of vascular events in carotid atherosclerotic disease. MMP-2 and MMP-9 are strongly correlated with plaque instability.

Assessment of MMP-9, TIMP-1, and COX-2 in normal tissue and in advanced symptomatic and asymptomatic carotid plaques

Background

Mature carotid plaques are complex structures, and their histological classification is challenging. The carotid plaques of asymptomatic and symptomatic patients could exhibit identical histological components.

Objectives

To investigate whether matrix metalloproteinase 9 (MMP-9), tissue inhibitor of MMP (TIMP), and cyclooxygenase-2 (COX-2) have different expression levels in advanced symptomatic carotid plaques, asymptomatic carotid plaques, and normal tissue.

Methods

Thirty patients admitted for carotid endarterectomy were selected. Each patient was assigned preoperatively to one of two groups: group I consisted of symptomatic patients (n = 16, 12 males, mean age 66.7 ± 6.8 years), and group II consisted of asymptomatic patients (n = 14, 8 males, mean age 67.6 ± 6.81 years). Nine normal carotid arteries were used as control. Tissue specimens were analyzed for fibromuscular, lipid and calcium contents. The expressions of MMP-9, TIMP-1 and COX-2 in each plaque were quantified.

Results

Fifty-eight percent of all carotid plaques were classified as Type VI according to the American Heart Association Committee on Vascular Lesions. The control carotid arteries all were classified as Type III. The median percentage of fibromuscular tissue was significantly greater in group II compared to group I (p < 0.05). The median percentage of lipid tissue had a tendency to be greater in group I than in group II (p = 0.057). The percentages of calcification were similar among the two groups. MMP-9 protein expression levels were significantly higher in group II and in the control group when compared with group I (p < 0.001). TIMP-1 expression levels were significantly higher in the control group and in group II when compared to group I, with statistical difference between control group and group I (p = 0.010). COX-2 expression levels did not differ among groups. There was no statistical correlation between MMP-9, COX-2, and TIMP-1 levels and fibrous tissue.

Conclusions

MMP-9 and TIMP-1 are present in all stages of atherosclerotic plaque progression, from normal tissue to advanced lesions. When sections of a plaque are analyzed without preselection, MMP-9 concentration is higher in normal tissues and asymptomatic surgical specimens than in symptomatic specimens, and TIMP-1 concentration is higher in normal tissue than in symptomatic specimens.

Histological Features of Symptomatic Carotid Plaques in Relation to Age and Smoking

Background and Purpose— Rates of incident and recurrent cardiovascular events rise steadily with age, due partly to more extensive atherosclerotic burden. However, in patients with similarly severe symptomatic carotid stenosis, increasing age is associated with a greater risk of ipsilateral ischemic stroke. This effect may be due to age-related differences in the pathology of symptomatic carotid plaques. However, previous studies of plaque pathology in relation to age have not accounted for potential confounders, particularly smoking, which is often less prevalent in the elderly population undergoing endarterectomy.

Method— We related patient age (<55, 55 to 64, 65 to 74, 75+ years) and smoking habit (never, exsmoker, recent smoker, and current smoker; and number of cigarettes smoked per day) to detailed histological assessments of 526 carotid plaques from consecutive patients undergoing carotid endarterectomy for symptomatic carotid stenosis.

Results— Three hundred seventy-nine (72.1%) patients were male (mean/SD age 66.6/8.7). Current/recent smokers were on average 7 years younger at carotid endarterectomy than ex-/never smokers ( P <0.001), and age at carotid endarterectomy decreased with increasing number of cigarettes smoked per day ( P trend=0.005). Plaques from current/recent smokers had a lower prevalence of intraplaque hemorrhage ( P -trend=0.01), but histology was otherwise similar to that in ex-/never smokers, and both groups showed similar changes with age. With increasing age, plaque calcification and large lipid core increased ( P <0.001 and P =0.01, respectively) and fibrous tissue ( P =0.01) decreased, but lymphocyte infiltration of the plaque ( P =0.03) and cap ( P =0.002) and overall plaque inflammation ( P =0.03) also decreased such that overall plaque instability was unrelated to age.

Conclusion— Smoking is associated with a lower age at carotid endarterectomy suggesting that it may accelerate the development and/or progression of atherosclerosis. However, the mechanisms of plaque instability seem largely unrelated to smoking. Plaques from younger patients had greater inflammatory cell infiltration, whereas those from older patients had a larger lipid core, but there were no age trends in overall plaque instability suggesting the increased risk of stroke in the elderly with symptomatic carotid stenosis is due to other factors.