Relationships between risk factors and morphological patterns of human carotid atherosclerotic plaques. A multivariate discriminant analysis

Unveiling the Hidden Power of Uromodulin: A Promising Potential Biomarker for Kidney Diseases

Uromodulin, also known as Tamm-Horsfall protein, represents the predominant urinary protein in healthy individuals. Over the years, studies have revealed compelling associations between urinary and serum concentrations of uromodulin and various parameters, encompassing kidney function, graft survival, cardiovascular disease, glucose metabolism, and overall mortality. Consequently, there has been a growing interest in uromodulin as a novel and effective biomarker with potential applications in diverse clinical settings. Reduced urinary uromodulin levels have been linked to an elevated risk of acute kidney injury (AKI) following cardiac surgery. In the context of chronic kidney disease (CKD) of different etiologies, urinary uromodulin levels tend to decrease significantly and are strongly correlated with variations in estimated glomerular filtration rate. The presence of uromodulin in the serum, attributable to basolateral epithelial cell leakage in the thick ascending limb, has been observed. This serum uromodulin level is closely associated with kidney function and histological severity, suggesting its potential as a biomarker capable of reflecting disease severity across a spectrum of kidney disorders. The UMOD gene has emerged as a prominent locus linked to kidney function parameters and CKD risk within the general population. Extensive research in multiple disciplines has underscored the biological significance of the top UMOD gene variants, which have also been associated with hypertension and kidney stones, thus highlighting the diverse and significant impact of uromodulin on kidney-related conditions. UMOD gene mutations are implicated in uromodulin-associated kidney disease, while polymorphisms in the UMOD gene show a significant association with CKD. In conclusion, uromodulin holds great promise as an informative biomarker, providing valuable insights into kidney function and disease progression in various clinical scenarios. The identification of UMOD gene variants further strengthens its relevance as a potential target for better understanding kidney-related pathologies and devising novel therapeutic strategies. Future investigations into the roles of uromodulin and regulatory mechanisms are likely to yield even more profound implications for kidney disease diagnosis, risk assessment, and management.

Coronary Artery Disease Events and Carotid Intima-Media Thickness in Type 1 Diabetes in the DCCT/EDIC Cohort

Background

Carotid artery intima‐media thickness (IMT) is associated with the risk of subsequent cardiovascular events in the general population. This association has not been established in type 1 diabetes.

Methods and Results

We studied if carotid IMT is associated with the risk of a first coronary artery disease event in participants with type 1 diabetes in the EDIC (Epidemiology of Diabetes Interventions and Complications) study, the long‐term observational follow‐up of the DCCT (Diabetes Control and Complications Trial). Between 1994 and 1996, common carotid artery and internal carotid artery IMT were measured with high‐resolution ultrasound in 1309 study participants with a mean age of 35 years and diabetes duration of 13.8 years; 52% were men. Cox proportional hazards models evaluated the association of standardized common carotid artery IMT and internal carotid artery IMT with subsequent cardiovascular events over the next 17 years. Models were adjusted for age, sex, mean hemoglobin A1c levels, and traditional cardiovascular risk factors. Associations of common carotid artery IMT with subsequent CAD were significant after adjustment for imaging device, sex, and age (hazard ratio [HR], 1.23 per 0.09 mm [95% CI, [1.04–1.45]; P=0.0141), but did not remain significant after further adjustment for traditional risk factors and hemoglobin A1c (HR, 1.14 per 0.09 mm [95% CI, 0.97–1.33]; P=0.1206). No significant associations with subsequent coronary artery disease events were seen for internal carotid artery IMT.

Conclusions

In the DCCT/EDIC cohort with type 1 diabetes, common carotid artery IMT, but not internal carotid artery IMT, is weakly associated with subsequent coronary artery events, an association eliminated after adjusting for coexistent traditional cardiovascular risk factors.

Registration

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT00360815 and NCT00360893.

Bifurcation analysis of a free boundary model of the atherosclerotic plaque formation associated with the cholesterol ratio

The low-density lipoprotein (LDL)/high-density lipoprotein (HDL)-cholesterol ratio has been shown to have a high correlation with the cardiovascular risk assessment. Is it possible to quantify the correlation mathematically? In this paper, we develop a bifurcation analysis for a mathematical model of the plaque formation with a free boundary in the early stage of atherosclerosis. This bifurcation analysis, to the ratio of LDL/HDL, is based on explicit formulations of radially symmetric steady-state solutions. By performing the perturbation analysis to these solutions, we establish the existence of bifurcation branches and derive a theoretical condition that a bifurcation occurs for different modes. We also analyze the stability of radially symmetric steady-state solutions and conduct numerical simulations to verify all theoretical results.

Carotid plaque imaging profiling in subjects with risk factors (diabetes and hypertension)

Carotid artery stenosis (CAS) due to the presence of atherosclerotic plaque (AP) is a frequent medical condition and a known risk factor for stroke, and it is also known from literature that several risk factors promote the AP development, in particular aging, smoke, male sex, hypertension, hyperlipidemia, smoke, diabetes type 1 and 2, and genetic factors. The study of carotid atherosclerosis is continuously evolving: even if the strategies of treatment still depends mainly on the degree of stenosis (DoS) determined by the plaque, in the last years the attention has moved to the study of the plaque components in order to identify the so called "vulnerable" plaque: features like the fibrous cap status and thickness, the volume of the lipid-rich necrotic core and the presence of intraplaque hemorrhage (IPH) are risk factors for plaque rupture, that can be studied with modern imaging techniques. The aim of this review is to give a general overview of the principle histological and imaging features of the subcomponent of carotid AP (CAP), focalizing in particular on the features of CAP of patients affected by hypertension and diabetes (in particular type 2 diabetes mellitus).

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.

Serum Uromodulin Predicts Less Coronary Artery Calcification and Diabetic Kidney Disease Over 12 Years in Adults With Type 1 Diabetes: The CACTI Study

OBJECTIVE

Novel biomarkers are needed to better predict coronary artery calcification (CAC), a marker of subclinical atherosclerosis, and diabetic kidney disease (DKD) in type 1 diabetes. We evaluated the associations between serum uromodulin (SUMOD [a biomarker associated with anti-inflammatory and renal protective properties]), CAC progression, and DKD development over 12 years.

RESEARCH DESIGN AND METHODS

Participants (n = 527, 53% females) in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study were examined during 2002-2004, at a mean age of 39.6 ± 9.0 years and a median duration of diabetes of 24.8 years. Urine albumin-to-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) determined by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation were measured at baseline and after a mean follow-up period of 12.1 ± 1.5 years. Elevated albumin excretion was defined as ACR ≥30 mg/g, rapid GFR decline (>3 mL/min/1.73 m²/year), and impaired GFR as eGFR <60 mL/min/1.73 m². SUMOD was measured on stored baseline plasma samples (Meso Scale Discovery). CAC was measured using electron beam computed tomography. CAC progression was defined as a change in the square root-transformed CAC volume of ≥2.5.

RESULTS

Higher baseline SUMOD level conferred lower odds of CAC progression (odds ratio 0.68; 95% CI 0.48-0.97), incident elevated albumin excretion (0.37; 0.16-0.86), rapid GFR decline (0.56; 0.35-0.91), and impaired GFR (0.44; 0.24-0.83) per 1 SD increase in SUMOD (68.44 ng/mL) after adjustment for baseline age, sex, systolic blood pressure, LDL cholesterol, and albuminuria/GFR. The addition of SUMOD to models with traditional risk factors also significantly improved the prediction performance for CAC progression and incident DKD.

CONCLUSIONS

Higher baseline SUMOD level predicted lower odds of both CAC progression and incident DKD over 12 years in adults with type 1 diabetes.

Atherosclerosis and Microvascular Complications: Results From the Canadian Study of Longevity in Type 1 Diabetes

OBJECTIVE

Type 1 diabetes carries a significant risk for cardiovascular mortality, but it is unclear how atherosclerosis associates with microvascular complications. We aimed to determine the relationships between atherosclerotic burden and neuropathy, retinopathy, and diabetic kidney disease (DKD) in adults with a ≥50-year history of type 1 diabetes.

RESEARCH DESIGN AND METHODS

Adults with type 1 diabetes (n = 69) underwent coronary artery calcification (CAC) volume scoring by wide-volume computerized tomography. Microvascular complications were graded as follows: neuropathy by clinical assessment, electrophysiology, vibration and cooling detection thresholds, heart rate variability, and corneal confocal microscopy; retinopathy by ultra-wide-field retinal imaging; and DKD by renal hemodynamic function measured by inulin and para-aminohippurate clearance at baseline and after intravenous infusion of angiotensin II. The cohort was dichotomized to high (≥300 Agatston units [AU]) or low (<300 AU) CAC and was stratified by diabetes status. A comparator group without diabetes (n = 73) matched for age and sex also underwent all study procedures except for retinal imaging.

RESULTS

CAC scores were higher in participants with type 1 diabetes (median Agatston score 1,000 [interquartile range = 222, 2,373] AU vs. 1 [0.75] AU in comparators, P < 0.001). In participants with type 1 diabetes, high CAC scores associated with markers of neuropathy and retinopathy, but not with DKD, or renal hemodynamic function at baseline or in response to angiotensin II.

CONCLUSIONS

The presence of high CAC in adults with longstanding type 1 diabetes was associated with large nerve fiber neuropathy and retinopathy but not with renal hemodynamic function, suggesting that neuropathy, retinopathy, and macrovascular calcification share common risk factors.

Pathogenesis of Lipid Disorders in Insulin Resistance: a Brief Review

PURPOSE OF REVIEW

Insulin resistance (IR) is recognized to play an important role in the pathogenesis of dyslipidemia. This review summarizes the complex interplay between IR and dyslipidemia in people with and without diabetes.

RECENT FINDINGS

IR impacts the metabolism of triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very low-density lipoprotein cholesterol (VLDL-C) by several mechanisms. Trials with insulin sensitizing therapies, including biguanides and thiazolidinediones, have provided inconsistent results on lipid lowering in people with and without diabetes. In this review, we focus on the pathophysiological interplay between IR and dyslipidemia and recapitulate lipid and lipoprotein data from insulin-sensitizing trials. Further research elucidating the reciprocal relationship between IR and dyslipidemia is needed to better target these important risk factors for cardiovascular disease.

Negative Carotid Artery Remodeling in Early Type 2 Diabetes Mellitus and Increased Carotid Plaque Vulnerability in Obesity as Assessed by Magnetic Resonance Imaging

Background Ischemic stroke from carotid plaque embolism remains a major cause of morbidity in patients with type 2 diabetes mellitus (T2 DM ). However, the effect of early T2 DM and obesity on carotid remodeling and plaque burden remains elusive. We assessed carotid remodeling and plaque composition by carotid magnetic resonance imaging in patients with short-duration T2 DM compared with a sex- and age-matched control group. Methods and Results One hundred patients with T2 DM (duration <5 years) and 100 sex- and age-matched controls underwent bilateral carotid artery magnetic resonance imaging in a 1.5-T magnetic resonance imaging scanner. Plaque burden was quantified by normalized wall index, maximum wall thickness, maximum wall area, and minimum lumen size. Plaque morphology was quantified by calcified plaque volume, necrotic core volume, and loose matrix volume. Magnetic resonance imaging data were available for 149 and 177 carotid arteries from T2 DM patients and controls, respectively. Adjusted for age and sex, T2 DM was associated with increased plaque burden indicated by a higher normalized wall index (ratio 1.03 [95% confidence interval, 1.002; 1.06], P=0.03), and negative remodeling indicated by a lower minimum lumen area (ratio 0.81 [0.74; 0.89], P<0.001), and lower maximum wall area (ratio 0.94 [0.88; 1.00], P=0.048) compared with controls. In both T2 DM and controls, body mass index ≥30.0 kg/m2 was associated with an 80% increase in total calcified plaque volume, and a 44% increase in necrotic core volume compared with body mass index <25.0 kg/m2. Conclusions Short-duration T2 DM was associated with increased carotid plaque burden and negative remodeling. Obesity was associated with increased carotid artery necrotic core volume and calcification independently of diabetes mellitus status. Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT 00674271.

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.

Pathology of Human Coronary and Carotid Artery Atherosclerosis and Vascular Calcification in Diabetes Mellitus

The continuing increase in the prevalence of diabetes mellitus in the general population is predicted to result in a higher incidence of cardiovascular disease. Although the mechanisms of diabetes mellitus-associated progression of atherosclerosis are not fully understood, at clinical and pathological levels, there is an appreciation of increased disease burden and higher levels of arterial calcification in these subjects. Plaques within the coronary arteries of patients with diabetes mellitus generally exhibit larger necrotic cores and significantly greater inflammation consisting mainly of macrophages and T lymphocytes relative to patients without diabetes mellitus. Moreover, there is a higher incidence of healed plaque ruptures and positive remodeling in hearts from subjects with type 1 diabetes mellitus and type 2 diabetes mellitus, suggesting a more active atherogenic process. Lesion calcification in the coronary, carotid, and other arterial beds is also more extensive. Although the role of coronary artery calcification in identifying cardiovascular disease and predicting its outcome is undeniable, our understanding of how key hormonal and physiological alterations associated with diabetes mellitus such as insulin resistance and hyperglycemia influence the process of vascular calcification continues to grow. Important drivers of atherosclerotic calcification in diabetes mellitus include oxidative stress, endothelial dysfunction, alterations in mineral metabolism, increased inflammatory cytokine production, and release of osteoprogenitor cells from the marrow into the circulation. Our review will focus on the pathophysiology of type 1 diabetes mellitus- and type 2 diabetes mellitus-associated vascular disease with particular focus on coronary and carotid atherosclerotic calcification.

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.

Increased expression of bFGF is associated with carotid atherosclerotic plaques instability engaging the NF-κB pathway

Unstable atherosclerotic plaques of the carotid arteries are at great risk for the development of ischemic cerebrovascular events. The degradation of the extracellular matrix by matrix metalloproteinases (MMPs) and NO-induced apoptosis of vascular smooth muscle cells (VSMCs) contribute to the vulnerability of the atherosclerotic plaques. Basic fibroblast growth factor (bFGF) through its mitogenic and angiogenic properties has already been implicated in the pathogenesis of atherosclerosis. However, its role in plaque stability remains elusive. To address this issue, a panel of human carotid atherosclerotic plaques was analyzed for bFGF, FGF-receptors-1 and -2 (FGFR-1/-2), inducible nitric oxide synthase (iNOS) and MMP-9 expression. Our data revealed increased expression of bFGF and FGFR-1 in VSMCs of unstable plaques, implying the existence of an autocrine loop, which significantly correlated with high iNOS and MMP-9 levels. These results were recapitulated in vitro by treatment of VSMCs with bFGF. bFGF administration led to up-regulation of both iNOS and MMP-9 that was specifically mediated by nuclear factor-kappaB (NF-kappaB) activation. Collectively, our data demonstrate a novel NF-kappaB-mediated pathway linking bFGF with iNOS and MMP-9 expression that is associated with carotid plaque vulnerability.

The risk factors associated with ultrasonic tissue characterization of carotid plaque in type 2 diabetic patients

AIMS

Little is known about the related factors of plaque echogenicity in diabetic subjects.

METHODS

This was a single-center, retrospective, study investigating a subgroup of patients of a previously published trial. We enrolled 179 middle-aged and older Japanese type 2 diabetic patients with carotid plaque, and examined the parameters related with echogenicity of carotid plaque evaluated by gray-scale median (GSM).

RESULTS

Proportion of males and body mass index (BMI) were significantly higher and HDL-cholesterol was significantly lower in the patients with low GSM (< 48) plaques (n = 89) as compared to those without it (n = 90). A multiple logistic regression analysis with gender, BMI, and HDL-cholesterol as independent variables and the presence of low GSM plaques as an objective variable showed that male (odds ratio (OR) 2.36, 95%CI 1.05-5.31, p = 0.037) and BMI (OR 1.12 [1.01-1.24], p = 0.029) were independently associated with low GSM plaques. Another multiple logistic regression analysis with gender, BMI, and low-HDL-cholesterolemia (HDL-C < 40 mg/dl) as independent variables showed that low-HDL-cholesterolemia (OR 2.30 [1.03-5.13], p = 0.042) and BMI (OR 1.11 [1.00-1.22], p = 0.046) were independently associated with low GSM plaques.

CONCLUSIONS

Our study suggests that gender, BMI and low-HDL-cholesterol are important determinants of the content of the vascular wall in diabetic subjects.

Long-term smoking results in haemostatic dysfunction in chronic smokers

BACKGROUND

Smoking has been known to cause endothelial dysfunction and bronchial carcinoma and duration of smoking has been implicated in the effects of smoking on regular smokers. This study evaluated the effects of long-term smoking on some coagulation markers in chronic smokers.

MATERIALS AND METHODS

A total of 78 chronic smokers (age, 41 ± 20 years) where grouped according to duration of time they have smoked (2-6 years, 7-11 years, 12-16 years and 17-21 years), and included in the study. Bleeding time (BT), whole-blood clotting time (WBCT), total platelet count (TPC), prothrombin time (PT) and activated partial thromboplastin time with kaolin (APTTK) were estimated in the subjects using standard operative procedures.

STATISTICAL ANALYSIS USED

Graph pad prism software (Statmate) version 2.0 and SPSS version 20.0 were used for the statistical analysis and the test of significance was calculated using paired Student's t-test.

RESULTS

There was an inverse correlation between the durations of smoking and BT, WBCT, PT and APTTK coagulation markers and a linear correlation between the different durations and TPC, in the chronic smokers. The strongest effects was in the 12-16 years and 17-21 years duration (P < 0.05).

CONCLUSION

The study revealed that long-term chronic cigarette-smoking can lead to haemostatic dysfunction in chronic smokers. Smoking should be generally discouraged as it could have far-reaching medical implications on this group of subjects, especially in bleeding emergency cases.

Increased vascularization of shoulder regions of carotid atherosclerotic plaques from patients with diabetes

OBJECTIVE

Increased vascularization is considered an important contributing factor for plaque vulnerability. Microvascular proliferative disease in patients with diabetes results in renal damage and visual loss. We assessed the hypothesis that vascularization in carotid atherosclerotic tissue is increased in diabetic patients, especially in the critical shoulder regions of the plaque.

METHODS

Carotid endarterectomy specimens, clinical data, and blood samples were collected from patients with symptomatic carotid artery stenosis (median 85 days after clinical event) and pharmacologic treatment for diabetes (n = 26) or no diabetes (n = 85). Plaques were fixed in formalin and transverse tissue sections prepared. Histopathology and immunohistochemistry were performed for detection of endothelial cells (anti-CD34), macrophages (anti-CD68), vascular endothelial growth factor (VEGF), and its receptor (VEGFR-2). Neovascularization was assessed as CD34(+) neovessel density in the entire section area and by the presence or absence of CD34(+) vessels in the shoulder and cap regions of the plaques.

RESULTS

The patient groups did not differ significantly in neovascularization in the entire transverse sections (2.0 vs 2.1 vessels/mm(2); P = .61) or in the fibrous cap (52% of the patients in both groups; P = .95). Neovascularization of the plaque shoulder regions was observed in 52% of the diabetic patients and in 26% of the nondiabetic patients (P = .028). VEGF-stained areas were similar in the two patient groups (0.4% and 0.2% of shoulder area; P = .61). Patients with diabetes had more VEGFR-2 (1.0% vs 0.2% of shoulder area; P < .016) and less CD68 staining (0.4% vs 3.6% of shoulder area; P < .008). Time from clinical event to surgery was positively associated with neovascularization of the plaque shoulder regions (≤90 days, 18% of patients; >90 days, 50% of patients; P = .002), independently of diabetes status.

CONCLUSIONS

Diabetes was associated with increased vascularization of the shoulder regions in patients with symptomatic carotid atherosclerotic plaques. This was accompanied by increased expression of VEGFR-2. The increased vascularization of the plaque shoulder regions may help explain why patients with diabetes are at increased risk of atherosclerotic complications.

Asymptomatic carotid plaque rupture with unexpected thrombosis over a non-canonical vulnerable lesion

OBJECTIVE

Several studies have demonstrated that carotid plaque rupture and thrombosis represent the most important factors correlated with the onset of acute cerebrovascular symptoms. Nevertheless, ruptured thrombotic plaques have been described also in asymptomatic patients. What still needs to be clarified is why a plaque rupture leads either to an acute ischemic syndrome or, in a minor group of patients, remains asymptomatic. The purpose of this study was to systematically compare the histologic features of thrombotic plaques both in asymptomatic and symptomatic patients in order to identify specific findings that could explain the peculiar clinical behavior that characterizes each of the clinical settings.

METHODS

A total of 157 thrombotic plaques from 60 asymptomatic patients and 97 with major stroke who consecutively underwent CEA were serially sectioned and studied by histology.

RESULTS

A minute cap disruption very frequently characterizes thrombotic plaques of asymptomatic patients and it was always smaller than large ulcers observed in thrombotic symptomatic plaques (651 ± 687μm vs. 4150 ± 3526, p=0.001). In asymptomatics this typical feature was associated with fewer inflammatory cells (20.1 ± 8.8 vs. 33.9 ± 26.1 cells × hpf, p=0.001), smaller lipidic-necrotic core (33.9%± 2.9% vs. 42.0% ± 2.4%; p=0.04) and larger calcification (16.2 ± 12.8% vs. 8.1 ± 12.2%, p=0.02). Symptomatic patients with thrombotic plaques showed higher incidence of metabolic syndrome (p=0.002) and moderate-high Framingham risk scores (p=0.001) comparing to asymptomatic individuals.

CONCLUSION

The transformation from a stable to a vulnerable plaque is a gradual process in the natural history of the disease and plaque rupture is an event not necessarily occurring at a late phase but also at earlier one. In this case, the rupture will be most likely smaller and clinically asymptomatic.

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.

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.

Atherosclerotic plaque volume and composition in symptomatic carotid arteries assessed with multidetector CT angiography; relationship with severity of stenosis and cardiovascular risk factors

The purpose of this study was to examine the volume and the composition of atherosclerotic plaque in symptomatic carotid arteries and to investigate the relationship between these plaque features and the severity of stenosis and the presence of cardiovascular risk factors. One hundred patients with cerebrovascular symptoms underwent CT angiography. We measured plaque volume (PV) and the relative contribution of plaque components (calcifications, fibrous tissue, and lipid) in the symptomatic artery. The contribution of different components was measured as the number of voxels within defined ranges of HU values (calcification >130 HU, fibrous tissue 60–130 HU, lipid core <60 HU). Fifty-seven patients had atherosclerotic plaque in the symptomatic carotid artery. The severity of stenosis and PV were moderately correlated. Age and smoking were independently related to PV. Patients with hypercholesterolemia had significantly less lipid and more calcium in their plaques than patients without hypercholesterolemia. Other cardiovascular risk factors were not significantly related to PV or plaque composition. Luminal stenosis of the carotid artery partly reflects the amount of atherosclerotic carotid disease. Plaque volume and plaque composition are associated with cardiovascular risk factors.

Hypertension and Hypercholesterolemia Differentially Affect the Function and Structure of Pig Carotid Artery

The purpose of this work was to compare the effects of hypertension and hypercholesterolemia on carotid endothelial function, structure, and vasa vasorum density. Seventeen pigs were randomized to a 12-week normal diet without (n=5), or with renovascular hypertension (HT; n=6), or to a high cholesterol diet (HC; n=6). Carotid arteries were studied by organ chambers (endothelial function) and microcomputed tomography (vasa vasorum), and tissue was processed for Sirius red staining and immunoblotting (vascular endothelium growth factor, endostatin, matrix metalloproteinase-9, and matrix metalloproteinase-2). HC and HT showed reduced vasodilation to acetylcholine as compared with controls, but HT also had a lower response to sodium nitroprusside. In addition, HT showed a higher content of organized collagen fibers and increased intima-media thickness. Vasa vasorum density was increased in HC but not in HT. Both HT and HC showed a proangiogenetic biochemical milieu (higher vascular endothelium growth factor, matrix metalloproteinases, and lower endostatin), but this was more pronounced in HC. Both hypertension and hypercholesterolemia induce endothelial dysfunction in the carotid artery. However, hypertension is also associated with greater fibrosis and vascular wall thickening, which might impair endothelium-independent vasorelaxation and vasa vasorum growth. Hypercholesterolemia is, in turn, associated with vasa vasorum neovascularization. These data suggest that carotid atherosclerosis can evolve through different mechanisms in relation to different risk factors.

Mechanism of lumen gain during coronary stent deployment in diabetic patients compared with non-diabetic patients

BACKGROUND

Diabetic patients show an increased incidence of restenosis after coronary angioplasty than non-diabetic patients. This may be because of differences in the mechanism of lumen gain during coronary revascularization in this population cohort.

DESIGN

This study analyses the mechanism of lumen gain during coronary stent deployment in diabetic patients compared with non-diabetic patients with intravascular ultrasound (IVUS).

METHODS

IVUS images were obtained prior to and after revascularization in 26 diabetic and 97 non-diabetic patients. The external elastic membrane cross-sectional area (EEM) and lumen cross-sectional area (LA) were measured. Plaque area (PA) was calculated as EEM minus LA. Differences between pre- and post-LA (deltaLA), EEM (deltaEEM) and PA (deltaPA) were calculated.

RESULTS

Pre-interventional PA (diabetic patients: 12.4 +/- 4.4 mm2 compared with non-diabetic patients: 10.7 +/- 3.6 mm2, = 0.04) and pre-interventional EEM (15.5 +/- 4.4 mm2 compared with 13.6 +/- 3.7 mm2 respectively, P = 0.02) were larger in the diabetic group. Postinterventional PA (10.2 +/- 3.2 mm2 compared with 8.0 +/- 3.4 mm2, P = 0.004) was also larger and postinterventional LA (6.3 +/- 2.2 mm2 compared with 7.4 +/- 2.4 mm2 = 0.04), deltaEEM (0.9 +/- 1.8 mm2 compared with 1.8 +/- 1.8 mm2 P = 0.04) and deltaLA (3.1 +/- 1.6 mm2 compared with 4.2 +/- 2.2 mm2, P = 0.03) were smaller in the diabetic group. The diabetic group exhibited longer lesion lengths (P = 0.04) and a higher inflation pressure was used during revascularization in this patient cohort (P = 0.02).

CONCLUSION

Diabetic patients have less reduction of PA during revascularization and because the vessel wall cannot be stretched outwards despite higher inflation pressure, postinterventional LA remains smaller than in the non-diabetic population cohort. This might be a rudiment for consideration of different treatment strategies such as cutting balloon or atherectomy prior to stenting in this population group in order to achieve better procedural outcome.

Hyperfibrinogenemia is associated with specific histocytological composition and complications of atherosclerotic carotid plaques in patients affected by transient ischemic attacks

BACKGROUND

Epidemiological studies have demonstrated that hyperfibrinogenemia is an independent risk factor for cerebrovascular atherosclerosis. However, the underlying mechanisms are poorly understood. We studied whether hyperfibrinogenemia could modify the histological composition of atherosclerotic plaque and precipitate carotid thrombosis resulting from rupture of the plaque.

METHODS AND RESULTS

We studied the histological composition of 71 carotid atherosclerotic plaques from patients who had undergone surgical endarterectomy after a first episode of transient ischemic attack. Patients were divided into 3 groups corresponding to the tertiles of plasma fibrinogen values. Hypercholesterolemia, hypertriglyceridemia, hypertension, diabetes, and smoking habit were also assessed. At the histological analysis, plaques of patients in the highest tertile of fibrinogen (>407 mg/dL) were characterized by a high incidence of thrombosis (66.7% of cases) compared with plaques of subjects in the lower (21.7%) (P=0.002) and middle (29. 2%) (P=0.009) tertiles. Plaque rupture was significantly associated with high fibrinogen levels (54.2%, P=0.003). Multivariate logistic regression indicated that hyperfibrinogenemia was an independent risk factor for a decrease in cap thickness (P=0.0005), macrophage foam cell infiltration of the cap (P=0.003), and thrombosis (P=0. 003). When the presence of other risk factors was accounted for, hyperfibrinogenemia remained an independent predictor of carotid thrombosis with an odds ratio of 5.83, compared with other risk factors.

CONCLUSIONS

The results of the present study add to the evidence that hyperfibrinogenemia, independently of other risk factors, is associated with a specific histological composition of carotid atherosclerotic plaques that predisposes them to rupture and thrombosis.

Identification of patients at risk for periprocedural neurological deficits associated with carotid angioplasty and stenting

BACKGROUND AND PURPOSE

Transient or permanent neurological deficits can occur in the periprocedural period following carotid angioplasty and stenting (CAS), presumably due to distal embolization and/or hemodynamic compromise. We performed this study to identify predictors of neurological deficits associated with carotid angioplasty and stent placement.

METHODS

We reviewed medical records and angiograms in a consecutive series of patients who underwent CAS for symptomatic or asymptomatic cervical internal carotid artery stenosis from June 1996 through December 1998. Using logistic regression analysis, we evaluated the effect of demographic, clinical, intraprocedural, and angiographic risk factors on subsequent development of periprocedural neurological deficits. Periprocedural neurological deficits were defined as new or worsening transient or permanent neurological deficits that occurred during or within 48 hours of the procedure.

RESULTS

A total of 111 patients (mean age 68.2+/-9.1 years) who underwent CAS for asymptomatic (n=54) or symptomatic (n=57) stenoses were included in this study. A total of 14 periprocedural neurological deficits (13%) were observed either during (n=4) or after (n=10) the procedure. Three identified variables were independently associated with periprocedural neurological deficits: symptomatic lesion (OR 8.3, 95% CI 1.6 to 42.6), length of stenotic segment >/=11.2 mm (OR 5.2, 95% CI 1.2 to 22.5), and absence of hypercholesterolemia (OR 5.4, 95% CI 1.4 to 20.9). Other variables, including age and degree of stenosis (defined by NASCET criteria), were not associated with periprocedural neurological deficits.

CONCLUSIONS

A combination of clinical and angiographic variables can be used to identify patients at risk for periprocedural neurological deficits after CAS. Such identification may help in selection of patients who may benefit from novel pharmacological and mechanical preventive approaches.

Age and sex differences in the distribution and ultrasound morphology of carotid atherosclerosis: the Tromsø Study

Atherosclerosis begins early in life and is the major underlying cause of cardiovascular morbidity and death. Yet, population-based information on age and sex differences in the extent and morphology of atherosclerosis throughout life is scarce. Carotid atherosclerosis can be visualized with B-mode ultrasound and is a marker of atherosclerosis elsewhere in the circulation. We assessed both the prevalence and the morphology of carotid atherosclerosis by B-mode ultrasound in 3016 men and 3404 women, 25 to 84 years old, who participated in a population health survey. The participation rate was 88%. Plaque morphology was graded according to whether a plaque was predominantly soft (echolucent) or hard (echogenic). Atherosclerotic plaques were found in 55.4% of the men and 45.8% of the women. In men, there was a linear increase with age in the prevalence of carotid atherosclerosis, whereas in women, there was a curvilinear age trend, with an inflection in the prevalence rate of women at approximately 50 years of age. The male predominance in atherosclerosis declined after the age of 50 years, the plaque prevalence being similar in elderly men and women. Men had softer plaques than women; this sex difference in plaque morphology increased significantly (P=0.005) with age. The sex difference in the prevalence of atherosclerosis and the female age trend in atherosclerosis show significant changes at the age of approximately 50 years, suggesting an adverse effect of menopause on atherosclerosis. The higher proportion of soft plaques in men compared with women increases with age and may partly account for the prevailing male excess risk of coronary heart disease in the elderly despite a similar prevalence of atherosclerosis in elderly men and women.

Carotid rupture and intraplaque hemorrhage: immunophenotype and role of cells involved

BACKGROUND

A complete immunohistochemical characterization in complicated carotid plaques is still lacking. The cellular components of 165 carotid endarterectomy specimens were analyzed to assess their role in the pathogenesis of plaque rupture and intraplaque hemorrhage without rupture.

METHODS AND RESULTS

The fibrous caps at the sites of plaque rupture showed CD68+ macrophages, T-lymphocytes, and scarce B-lymphocytes. Ruptured plaques showed mononuclear infiltrates in the caps, shoulders, and bases of the plaques in 85% of the cases. Only 46% of nonruptured plaques showed such infiltrates (P <.0001). Two types of lipid cores were recognized: avascular or mildly vascularized and highly vascularized. The vessels of the latter type reacted with CD31 and CD34. In 57.5% of the cases, the base and the shoulders of the plaques showed neoformed, CD34+ vessels, often surrounded by mononuclear infiltrates. Intraplaque hemorrhage without rupture had highly vascularized lipid cores in all cases. T-lymphocytes and macrophages were in close contact with neoformed vessels.

CONCLUSIONS

Plaque rupture is characterized by mononuclear cell infiltration of the caps, whereas intraplaque hemorrhage without rupture is characterized by extensive vascularization of the plaque.

Association between angiotensin I-converting enzyme genotypes, extracranial artery stenosis, and stroke

The insertion(I)/deletion(D) polymorphism of the angiotensin-converting-enzyme (ACE) gene has been associated with an increased risk of myocardial infarction, lacunar stroke, and with an increased intimal-medial thickness in several populations. The aim of this study was to evaluate whether the ACE I/D genotype is associated with stenosis of extracranial arteries and stroke in middle-aged and aged men and women. We studied 388 patients (247 male, 141 female) using Doppler and Duplex ultrasound of the extracranial arteries. Patients' history was obtained by standard questionnaire and by the hospital case records. Genomic DNA was analyzed by polymerase chain reaction (PCR) to identify the I/D polymorphism, with a second insertion specific PCR in samples classified as homozygous DD genotypes to prevent mistyping. The ACE genotype groups (DD 132, ID 164, II 92) were well matched for the basic characteristics. The DD genotype was more common in patients with extracranial artery stenosis > or = 50%, compared with patients without stenosis (59/147 versus 73/241, odds ratio 1.54, 95%-CI 1.01-2.37), but was not associated with a history of stroke (30/91 versus 102/297, odds ratio 0.94, 95%-CI 0.57-1.54). The association of the DD genotype with extracranial artery stenosis was also present in hypertensive subjects (n = 206, odds ratio 1.76, 95%-CI 0.99-3.17). In the whole group multiple logistic regression analysis revealed that the association of the DD genotype with extracranial artery stenosis was independent of age, gender, hypertension, hyperlipidemia, and diabetes. In conclusion, the ACE DD genotype is a weak risk factor for hemodynamically relevant stenosis of extracranial arteries, but not for stroke.

Reproducibility of ultrasound assessment of carotid plaque occurrence, thickness, and morphology. The Tromsø Study

BACKGROUND AND PURPOSE

Ultrasonography is increasingly used in vascular research, but there is limited information about the reproducibility of the ultrasound method for screening purposes. In this study the reproducibility of ultrasound assessment of carotid plaque occurrence, thickness, and morphology was examined within the setting of a population health survey.

METHODS

In 1994/1995, 6720 participants in the Tromsø Study, Norway, underwent B-mode ultrasound scanning of the right carotid artery. The between- and within-sonographer reproducibility of ultrasound assessment of plaque occurrence and thickness was estimated by repeated scanning of a random sample of 107 participants. The between- and within-sonographer reproducibility of plaque morphology classification (echogenicity, four categories and heterogeneity, two categories) was determined by repeated reading of videotaped images of 119 randomly selected arteries with plaques.

RESULTS

Between- and within-sonographer agreement on plaque occurrence was substantial with kappa values (95% CI) of 0.72 (0.60 to 0.84) and 0.76 (0.63 to 0.89), respectively. Reproducibility of plaque thickness measurements was moderate, with mean absolute differences ranging between 0.25 and 0.55 mm (coefficients of variation between 13.8% and 22.4%). Agreement on plaque morphology classification was high, with kappa values ranging between 0.54 and 0.73.

CONCLUSIONS

Population screening using B-mode ultrasound provides a valuable means for the detection and morphological evaluation of carotid plaques, whereas measurements of plaque thickness are subject to considerable measurement error.

Coronary artery calcium in acute coronary syndromes: a comparative study of electron-beam computed tomography, coronary angiography, and intracoronary ultrasound in survivors of acute myocardial infarction and unstable angina

BACKGROUND

Quantification of coronary artery calcified plaques by electron-beam CT (EBCT) may predict cardiovascular events. However, whereas advanced coronary atherosclerotic plaques can be identified, mildly stenotic lipid-rich (soft) plaques may be difficult to detect. The value of EBCT in a subgroup of patients has therefore been questioned. To investigate this, we evaluated patients with acute coronary syndromes by EBCT and compared the results with coronary angiography and, in patients with an indeterminate angiogram, intracoronary ultrasound (ICUS).

METHODS AND RESULTS

EBCT was performed in 118 consecutive patients (57+/-11 years of age) with previous myocardial infarction (n=101) or unstable angina (n=17). A standard protocol requiring a CT density >130 Hounsfield units in an area > or =1.03 mm2 was used for the definition of coronary artery calcium. We found that 110 patients had moderate to severe coronary artery disease by coronary angiography, and 8 had either mildly stenotic plaques at a single site (4 patients, confirmed by ICUS) or nonatherosclerotic causes of the unstable coronary syndrome (4 patients). One hundred and five of the 110 patients (96%) with moderate to severe angiographic disease but only 1 of the 8 other patients (13%) had a positive EBCT. Patients with acute coronary syndromes and negative EBCTs were significantly younger than patients with positive EBCTs (46+/-12 versus 58+/-10 years, P<.001), and a higher percentage was actively smoking (100% of the smokers versus 46%, P<.05).

CONCLUSIONS

The vast majority of patients with acute coronary syndromes and at least moderate angiographic disease have identifiable coronary calcium by EBCT. Those patients with negative EBCTs have minimal or no atherosclerotic plaque formation. They are younger and tend to be active cigarette smokers.

Age-related changes affecting atherosclerotic risk. Potential for pharmacological intervention

The incidence of cardiovascular diseases that are related to the atherosclerotic process increases exponentially with age. Organ lesions, the clinical manifestation of atherosclerotic disease, are late events due to complications in the plaque (ulceration, thrombosis, calcification) which are the result of an increased vulnerability to disruption of a previously stable plaque. The higher incidence of age-related clinical events could be explained by a rising sensitivity of plaques to destabilising factors, both parietal and humoral. The increased probability that a plaque in an elderly patient will became vulnerable could be related to those destabilising factors that significantly increase with aging, such as advanced glycation end-products. For these reasons, it seems most important that the analysis of these age-related destabilising factors, rather than those factors that promote the development of early atherosclerotic plaques, should be undertaken. Taking the point of view of a pharmacological intervention, this should eventually lead to a more complete understanding of this process.

Influence of vascular risk factors for atherosclerotic carotid artery plaque progression

BACKGROUND AND PURPOSE

Investigations regarding arteriosclerosis of carotid arteries showed an association between increased intima-media thickness and vascular risk factors. A newly developed three-dimensional ultrasound method increases the reproducibility of plaque volume measurements because more exact volume measurements can be performed with a reduction of the disadvantages of two-dimensional measurements. In a pilot study the influence of vascular risk factors on carotid artery plaque progression was examined.

METHODS

Volumes of atherosclerotic plaques in carotid arteries in 54 patients were measured with a three-dimensional ultrasound system during a 12-month period to determine the relationship between progression or regression of plaque volume, vascular risk factors, dose of aspirin, and flow turbulence in the plaque region.

RESULTS

A progression of plaque volume occurred in 67% (36/54) of all plaques. In no plaque was a regression of plaque volume seen. The optimal adjustment of all risk factors showed a significant influence on plaque progression (r = .31). Diastolic blood pressure was the strongest predictor of plaque progression (P < .01), followed by diabetes (P < .03). Turbulence in the plaque region was found in 78% of the patients in the progression group (n = 36) versus 61% in the nonprogression group (n = 18) but was not significant. Dose of aspirin (100 mg versus 250/300 mg) had no influence on plaque volume after 1 year.

CONCLUSIONS

Treatment of vascular risk factors reduces the progression of carotid artery plaque volume in three-dimensional ultrasound. The most important factor for plaque progression is a high diastolic blood pressure. Turbulence in the flow pattern and the examined doses of aspirin showed no significant influence.

Evidence that the death of macrophage foam cells contributes to the lipid core of atheroma

Sections of human atherosclerotic lesions of different stages show that, in early lesions, the acellular lipid core is usually immediately adjacent to the deepest edge of a collection of macrophage foam cells. Advanced lesions with a large lipid core have variable numbers of macrophage foam cells, close to the lateral edges, or shoulders, of the core. In both early and advanced lesions, some of the macrophages nearest the core appear to be dying. Lipid cores contain two materials which in earlier lesions are found only in macrophages, namely ceroid and CD68 antigen, but do not contain recognisable smooth muscle cell actin. It is concluded that death of macrophage foam cells contributes to the origin and slow enlargement of the lipid core. The cause of macrophage death is not yet certain, but is under investigation.