Prevalence of and risk factors associated with carotid artery stenosis: the Tromsø Study

Carotid ultrasound assessment of patients with coronary artery disease: a useful index for risk stratification

Carotid disease is a common finding in patients with coronary artery disease (CAD) and its presence is associated with worse clinical outcomes. Intima-media thickness provides incremental value over traditional risk factors in predicting cardiovascular events; however, it does not predict the absence of CAD or its extent and severity. The presence of carotid plaques is associated with an increased risk of cardiovascular events in patients with CAD regardless of the treatment strategy (medical therapy alone or myocardial revascularization). Hence, we advocate the screening of patients with diagnosed CAD for carotid atherosclerosis. The prognostic impact of ultrasound characteristics of carotid plaques on cardiovascular outcomes of patients with CAD remains controversial.

Guidelines for Screening of Extracranial Carotid Artery Disease: A Statement for Healthcare Professionals from the Multidisciplinary Practice Guidelines Committee of the American Society of Neuroimaging; Cosponsored by the Society of Vascular and Interventional Neurology

The aim of this new statement is to provide comprehensive and timely evidence-based recommendations on the screening for asymptomatic carotid artery stenosis in the general population and selected subsets of patients. Recommendations are included for high-risk persons in the general population; patients undergoing open heart surgery including coronary artery bypass surgery; patients with peripheral vascular diseases, abdominal aortic aneurysms, and renal artery stenosis; patients after radiotherapy for head and neck malignancies; patients following carotid endarterectomy, or carotid artery stent placement; patients with retinal ischemic syndromes; patients with syncope, dizziness, vertigo or tinnitus; and patients with a family history of vascular diseases and hyperhomocysteinemia. The recommendations are based on prevalence of disease, anticipated benefit, and concurrent guidelines from other professional organizations in selected populations.

The significance of multiple risk factors for early carotid atherosclerosis in Japanese subjects

OBJECTIVE

The aim of this study was to assess the significance of multiple risk factors for early carotid atherosclerosis in the Japanese population.

METHODS

The relation between traditional vascular risk factors and serum high-sensitivity CRP (hs-CRP) or atherosclerotic lesions in the carotid arteries detected by B-mode ultrasonography was evaluated.

PATIENTS

The subjects were 1,880 persons (1,240 men and 640 women, mean age 55+/-10 years old) without ischemic stroke, infection or collagen diseases.

RESULTS

In the men, the odds ratio (OR) for atherosclerotic lesion was increased at 1.90 (95% CI: 1.05-3.43, P=0.032) in those with one risk factor, 2.42 (1.36-4.32, P=0.002) in those with two, and 2.95 (1.69-5.16, P<0.001) in those with three or more. In the women, the OR was similarly increased 1.93 (95% CI: 1.04-3.56, P=0.035) for one risk factor, 2.31 (1.23-4.33, P=0.009) for two, and 3.52 (1.80-6.87, P<0.001) for three or more. The mean hs-CRP concentration increased significantly with the increasing number of risk factors (men and women, P<0.001) and with the degree of carotid arterial stenosis (men, P=0.011; women, P=0.008).

CONCLUSION

Multiple risk factors are more predictive than a single risk factor for early carotid atherosclerosis in the Japanese population.

Stroke Risk of Asymptomatic Intra- and Extracranial Large-Artery Disease in Apparently Healthy Adults

BACKGROUND

The predictive value of asymptomatic intracranial artery stenosis for future stroke remains uncertain. The aim of this study is to assess the stroke risk of asymptomatic intracranial artery stenosis and to compare it with that of extracranial artery disease.

METHODS

The study subjects were 2,924 participants (mean age 55 years) without any history of stroke. We examined the relation between intra- or extracranial large-artery disease and subsequent cerebrovascular events (mean follow-up 63 months).

RESULTS

The incidence rate of total cerebrovascular events in persons with intracranial artery stenosis was 1.3% per year. In the group without plaque in the extracranial carotid arteries, the annual rate of total cerebrovascular events was only 0.6%, but in the group with plaque, the rate was 3.6%. Kaplan-Meier analysis of total events showed a significant difference between the 2 groups (p = 0.002).

CONCLUSIONS

The stroke risk in subjects with asymptomatic extracranial artery disease is markedly increased if intracranial artery stenosis is also present.

Role of hyperlipidemia in atherosclerotic plaque formation in the internal carotid artery

PURPOSE

The role of hyperlipidemia in atherosclerotic changes of the carotid artery is controversial. The aims of this retrospective study were to assess (1) the relationship between total serum cholesterol and triglyceride and the grade of internal carotid artery stenosis and (2) whether total serum cholesterol and triglyceride levels are independent risk factors for internal carotid artery atherosclerosis.

METHODS

The files of 1,934 acute ischemic stroke patients were investigated retrospectively. The atherosclerotic involvement of the internal carotid artery was assessed via duplex sonography as percent of stenosis and was graded as follows: group 1, no plaque; group 2, <30% stenosis; group 3, 30-99% stenosis; and group 4, occlusion.

RESULTS

The mean age of the patients was 66.9 +/- 12.8 years. Patients without any plaque had significantly lower cholesterol levels compared with those with any degree of internal carotid artery stenosis. Univariate analysis revealed that age (p < 0.001), sex (p < 0.001), hypertension (p < 0.05), cholesterol (p < 0.01), triglycerides(p < 0.05), and smoking (p < 0.001) were significant contributors to atherosclerosis. In the ordinal logistic regression model, age (p < 0.001), sex (p < 0.001), smoking(p < 0.001), and cholesterol (p < 0.05) remained independent predictors of internal carotid artery atherosclerosis.

CONCLUSIONS

Total serum cholesterol level seems to be an independent risk factor of atherosclerosis in the carotid artery.

Monocyte count is a predictor of novel plaque formation: a 7-year follow-up study of 2610 persons without carotid plaque at baseline the Tromsø Study

BACKGROUND AND PURPOSE

Activation of monocytes and differentiation into lipid-laden macrophages are fundamental events in generation of atherosclerotic lesions. There exist few data on monocyte activity and the risk for atherosclerosis. In this prospective population-based study, we examined whether monocyte count in blood is a predictor of future plaque formation in persons without pre-existing carotid atherosclerosis.

METHODS

At baseline, we measured monocyte count, white cell count (WCC), fibrinogen, intima-media thickness (IMT), and traditional cardiovascular risk factors in 2610 men and women aged 25 to 82 years who on ultrasound had no plaque in their right carotid artery. After 7 years of follow-up, a new ultrasound screening was performed and the number of novel plaques was grouped as none, 1 plaque, and 2 or more plaques.

RESULTS

In multivariate analysis, monocyte count, age, sex, total cholesterol, current smoking, systolic blood pressure, and IMT were independent predictors of novel plaque formation. No significant association was found between plaque formation and either WCC or fibrinogen. For 1 standard deviation (0.17x10(9)) increase in monocyte count, the risk of being in a higher plaque category increased by 18% (OR, 1.18; 95% CI, 1.08 to 1.29). In the highest monocyte quartile, the risk for having plaque compared with the lowest quartile was 1.85 (OR) (95% confidence interval, 1.41 to 2.43). Repeating the analysis without IMT did not change the monocyte estimate. Excluding subjects with cardiovascular disease and diabetes mellitus from analysis neither changed the monocyte estimate.

CONCLUSIONS

Monocyte count is an independent predictor of future plaque formation in subjects without pre-existing carotid atherosclerosis.

Non-invasive cardiovascular risk assessment in women with type 2 diabetes

This study assessed and compared carotid intima-media thickness (IMT) in postmenopausal women with type 2 diabetes with that in postmenopausal women without type 2 diabetes and compared risk factors that contribute to increased carotid IMT in these groups of women. Carotid IMT, a non-invasive assessment of cardiovascular risk, was measured using high-resolution ultrasound in 20 postmenopausal women with type 2 diabetes and 20 postmenopausal women without type 2 diabetes who had no known coronary heart disease. Risk factors (age, race, family history, diabetes, hypertension, high cholesterol, years past menopause, use of hormone replacement therapy, perceived level of physical activity, and body mass index) known to contribute to coronary heart disease were also assessed. Mean carotid IMT was .88 mm for women with type 2 diabetes compared with .74 mm for women without type 2 diabetes. There were no differences between groups in age, race, cholesterol, and perceived level of physical activity. Women with type 2 diabetes, however, reported more hypertension ( P = .004), greater body mass index ( P = .026), and less use of hormone replacement therapy ( P = .027). Of concern is that 10% of the women with diabetes had stenosis that required surgical intervention. Findings suggest that carotid IMT is a valid way to screen for cardiovascular risk, particularly in postmenopausal women who are at high risk for coronary heart disease. It may also be a feasible, non-invasive method for the detection and prevention of the macrovascular complications of diabetes.

Focused screening for occult carotid artery disease: patients with known heart disease are at high risk

OBJECTIVES

Stroke puts a major financial burden on our healthcare system. However, carotid duplex scanning performed as a screening test for occult carotid artery stenosis (CAS) currently is not reimbursed by Medicare. The goals of this study were to develop a cost-effective stroke screening program, to determine the prevalence of potential causes of stroke in this population, and to define a population at high risk in which screening would be most effective.

METHODS

In a community-based stroke screening program, patients were eligible if they were older than 60 years and had a history of either hypertension, heart disease, or cigarette smoking, or a family history of stroke. Screening included blood pressure determination, an electrocardiographic rhythm strip, and a previously validated modified carotid duplex ultrasound examination to detect CAS 50% or greater. The relationships between standard demographic risk factors and screening outcomes were analyzed.

RESULTS

Screening was performed in 610 patients. Unilateral or bilateral CAS was detected in 66 patients (10.8%). The finding of occult CAS was more prevalent than that of new hypertension (2.6%) or new atrial fibrillation (0.5%). Patients with known hypertension were significantly more likely to have CAS than were those without hypertension (12.7% vs 7.8%; P =.05). Patients with heart disease were significantly more likely to have CAS than were those without heart disease (18.2% vs 8%; P <.0001). Patients with both risk factors were significantly more likely to have occult carotid artery disease than were patients without either risk factor (22.1% vs 8.5%; P <.0001). Multivariate analysis with logistic regression revealed a history of heart disease as an independent predictor of occult carotid artery disease (odds ratio 95% confidence interval, 1.4-4.4). Type of heart disease was not a significant factor in predicting occult CAS. Direct cost of the screening, including community outreach, nurses, technicians, support staff, and miscellaneous expenses, was less than $75 per patient.

CONCLUSIONS

In a screening program for treatable causes of potential stroke, CAS was the most commonly diagnosed disease. More than one of every five patients with known hypertension and heart disease had occult CAS. Known heart disease of any type was a significant independent predictor of occult CAS. Screening for treatable causes of potential stroke can be cost-effective. This information could help to further target populations to screen for occult CAS and to justify reimbursement for screening carotid duplex scanning examinations.

Epidemiology of smoking-induced cardiovascular disease

Cigarette smoking is a major cause of coronary heart disease, stroke, aortic aneurysm, and peripheral vascular disease. The risk is manifest both as an increased risk for thrombosis of narrowed vessels and as an increased degree of atherosclerosis in those vessels. The cardiovascular risks owing to cigarette smoking increase with the amount smoked and with the duration of smoking. Risks are not reduced by smoking cigarettes with lower machine-measured yields of tar and nicotine, but those who have only smoked pipes or cigars seem to have a lower risk for cardiovascular diseases. Cessation of cigarette smoking reduces disease risks, although risks may remain elevated for a decade or more after cessation.

Screening for asymptomatic internal carotid artery stenosis and aneurysm of the abdominal aorta: comparing the yield between patients with manifest atherosclerosis and patients with risk factors for atherosclerosis only

OBJECTIVE

The purpose of this study was to investigate whether screening for internal carotid artery stenosis (ICAS) and aneurysm of the abdominal aorta (AAA) is indicated in patients with either manifest atherosclerotic disease or with only risk factors for atherosclerosis.

STUDY DESIGN

Data were obtained for 2274 patients enrolled in the SMART study, an ongoing single-center, prospective cohort study of patients referred to our vascular center with manifest atherosclerotic disease (peripheral atherosclerotic disease [PAD]; transient ischemic attack [TIA], stroke, or ICAS; AAA; angina pectoris; or myocardial infarction [MI]) or with only risk factors for atherosclerosis (diabetes mellitus, hypertension, hyperlipidemia). The presence of ICAS or AAA was determined with duplex scanning and ultrasonography.

RESULTS

The prevalence of ICAS 70% or greater is low in patients with risk factors for atherosclerosis only (1.8%-2.3%), intermediate in patients with angina pectoris or MI (3.1%), and highest in patients with PAD (12.5%) or AAA (8.8%). The prevalence of AAA 3 cm or larger is low in patients with risk factors for atherosclerosis only (0.4-1.6%), intermediate in patients with angina pectoris or MI (2.6%), and highest in patients with PAD (6.5%) or TIA, stroke, or ICAS (6.5%). The prevalence of AAA larger than 5 cm is low in all of the considered patient groups. The yield of screening can be optimized through selection on the basis of simple patient characteristics. In patients with PAD, selecting those with advanced age (>54 years) increased the prevalence of ICAS to 21.8%. Selecting patients with lower diastolic blood pressure (<83 mm Hg) increased the prevalence of ICAS to 17.9%. In patients with both advanced age and lower diastolic blood pressure, the prevalence of ICAS increased to 34.7%. Selecting patients with advanced age increased the prevalence of AAA 3 cm or larger to 9.6%. In patients with TIA, stroke, or ICAS, selecting those with advanced age increased the prevalence of AAA 3 cm or larger to 8.2%. Selecting patients with taller stature (>169 cm) increased the prevalence of AAA 3 cm or larger to 9.3%. In patients with advanced age and taller stature, the prevalence of AAA 3 cm or larger increased to 13.1%.

CONCLUSIONS

Screening for ICAS should be limited to patients referred with PAD or AAA, especially those with advanced age or with low diastolic blood pressure. Screening for AAA should be limited to patients referred with PAD or with TIA, stroke, or ICAS, particularly those with advanced age or tall stature. In patients referred with angina pectoris or MI and those referred with only risk factors for atherosclerosis, screening cannot be endorsed.

Early-onset carotid atherosclerosis is associated with increased intima-media thickness and elevated serum levels of inflammatory markers

BACKGROUND AND PURPOSE

Several factors have been held responsible for the development of atherosclerosis. To avoid the masking effect of age, we evaluated correlates of carotid atherosclerosis in patients <55 years of age.

METHODS

Plasma lipids, oxidative resistance of low-density lipoprotein, homocysteine, inflammatory markers, plasma viscosity, and red cell deformability were measured in fasting blood samples of 100 subjects: 45 patients with >30% stenosis of the internal carotid artery, 20 patients with carotid occlusion, and 35 control subjects. Stenosis and intima-media thickness (IMT) of the carotid artery were evaluated by duplex ultrasound.

RESULTS

White blood cell (WBC) count, plasma fibrinogen, C-reactive protein (CRP), and lipoprotein(a) levels were significantly higher in patients than in control subjects, and patients had increased IMT (P<0.01 for all comparisons). There was a tendency for higher homocysteine levels in patients. Smokers had higher WBC, fibrinogen, and CRP levels. After the effect of smoking was controlled for, WBC count, natural logarithmic transform of homocysteine, and online-measured IMT remained significantly higher in patients than in control subjects. WBC, fibrinogen, and CRP levels were highest in the highest IMT quartile (P=0.012, P=0.007, and P=0.036, respectively).

CONCLUSIONS

Inflammatory markers and homocysteine have a more important role than lipid factors in early-onset carotid atherosclerosis. We cannot recommend the measurement of low-density lipoprotein peroxidation as a routine screening test to identify high-risk patients for early-onset carotid atherosclerosis. The confounding effect of smoking on inflammatory markers should be considered in studies on atherosclerosis.

Impact of albumin synthesis rate and the acute phase response in the dual regulation of fibrinogen levels in hemodialysis patients

BACKGROUND

Fibrinogen is a risk factor for cardiovascular disease. It also is an acute phase protein (APP) and its plasma concentration increases with inflammation. Fibrinogen synthesis correlates with albumin synthesis in nephrotic patients and in patients with an expanded plasma volume even when serum albumin is normal and there is no inflammatory disease. The relationships among albumin synthesis, the acute phase response and plasma fibrinogen levels in hemodialysis patients are unknown.

METHODS

In 74 hemodialysis patients, albumin synthesis, plasma volume (PV) and acute phase proteins (APPs) C-reactive protein (CRP), alpha1 acid glycoprotein (alpha1 AG), ceruloplasmin (Cer), and interleukin 6 (IL-6) were measured in serum and fibrinogen in plasma, and the results analyzed by multiple regression analysis. CRP, IL-6, alpha1 AG, Cer and fibrinogen were measured monthly, which enabled us to determine whether changes in these APPs correlated with the levels of and variability in plasma fibrinogen over time using a longitudinal modeling approach. Length of follow-up for the 74 patients ranged from 3.25 to 67.5 months.

RESULTS

Baseline fibrinogen (548.6 +/- 106. 4 mg/dL) was significantly greater than levels reported for normal adults and correlated positively with albumin synthesis (P < 0.001), age (P < 0.001) and log CRP (P = 0.002) and negatively with PV (P < 0.001). Longitudinally, fibrinogen varied positively with long-lived APPs, Cer and alpha1 AG, as well as the short-lived APP, CRP.

CONCLUSION

Plasma fibrinogen concentration is high in HD patients and directly correlates with increased albumin synthesis rates and the serum levels of APPs. Fibrinogen levels also correlate negatively with PV. Fibrinogen levels vary over time in synchrony with levels of other long-lived APPs, supporting the hypothesis that fibrinogen is regulated in part as a component of the acute phase response and in part by factors that increase albumin synthesis.