B-mode ultrasound-detected carotid artery lesions with and without acoustic shadowing and their association with markers of inflammation and endothelial activation: the atherosclerosis risk in communities study

Assessment of carotid artery ultrasonography in the presence of an acoustic shadow artifact

Background

B-mode and Color Doppler ultrasonography (CDUS) are the methods of choice for screening and determining the degree of Carotid artery stenosis. The evaluation of stenosis with calcification may be hampered by a common CDUS artifact known as acoustic shadow (AS). Our objective was to assess the change in reliability of CDUS readings in the presence of an AS artifact.

Methods

Single center retrospective observational study. Included were patients with either an AS artifact or high-grade stenosis (defined by peak systolic velocity (PSV) > 240 cm/s) demonstrated in CDUS, and had a CT angiography (CTA) done within 6 months of the sonographic exam. All subjects were identified through the Tel-Aviv Sorasky medical center (TASMC) CDUS unit registry from which clinical information was extracted. CDUS images were manually reviewed grading AS magnitude. All CTAs were reviewed and reconstructed for accurate assessment of percent stenosis and were used as gold standard.

Results

The study cohort included 227 consecutive patients (corresponding with 454 internal carotid arteries) meeting inclusion criteria. 43.2% of the arteries (n = 195) had an AS artifact present on CDUS, regardless of percent stenosis, with a large artifact present in 6.7% arteries (n = 30). Older age was significantly related to the presence of AS artifact (p < 0.001). In the study cohort as a whole there was a strong correlation between percent stenosis on CTA and PSV values (Pearson’s r 0.672, p < 0.001) regardless of AS existence. The CDUS sensitivity and specificity for predicting severe stenosis were 82 and 73% respectively. The presence of a small AS slightly diminished the correlation between CDUS and CTA results without compromising CDUS reliability. A large AS severely affected the correlation between CDUS and CTA exams (Pearson’s r = 0.24, p = 0.27) and reduced CDUS reliability with a sensitivity and specificity of 62%.

Conclusion

The presence of a large AS severely degrades the accuracy of the routine CDUS measurements. In these cases, the patient should be referred to a CDUS exam including doppler-measurement of periorbital arteries and intracranial arteries in addition to other imaging modalities such as CTA or MRA in order to assess future stroke risk.

Common Carotid Artery Calcification Impacts on Cognitive Function in Older Patients

INTRODUCTION

Cognitive impairment and dementia represent an emerging health problem. Cardiovascular (CV) risk factors contribute to cognitive impairment.

AIM

To investigate the effect of vascular calcification on cognitive impairment and dementia, independently of plaque and traditional CV risk factors.

METHODS

Four hundred and sixty-nine patients (age of 78.6 ± 6.1 years, 74.4% women) were studied. Traditional CV risk factors levels, cognitive function (MMSE), brain CT scan, and other vascular parameters were measured. Common Carotid Artery (CCA) plaque and calcification were evaluated by ultrasound.

RESULTS

CCA calcification was associated with a lower MMSE score than in subjects with no CCA calcification (23.7 ± 0.3 versus 25.5 ± 0.8; p = 0.015), after controlling for age, sex, education, blood pressure levels, diabetes, creatinine, lipid lowering therapy, neuroimaging alteration, and CCA plaque. Similarly, CCA calcification was associated with higher odds of dementia regardless of the presence of CCA plaque (OR 1.70, 95% CI 1.01-2.94, p < 0.05). This trend was not observed when stratifying patients according to the presence of CCA plaque.

CONCLUSION

CCA calcification is associated with cognitive impairment and dementia, independently of established CV risk factors and CCA plaque. The impact of arterial calcification on cognition seems largely independent of arterial stiffness.

Carotid artery calcification score and its association with cognitive impairment

Purpose

To retrospectively investigate the possible association between carotid artery calcification score (CS) and cognitive impairment in carotid artery stenosis (CAS) patients.

Patients and methods

Carotid artery was measured in 102 patients with cervical carotid arteries using Color Doppler ultrasound, multi-detector row spiral CT angiography and MRI scanning. Correlation analysis between CSs obtained by MD CT and cognitive scores was performed, and the correlation between CSs and vascular stenosis degree and MRI-measured plaque histological (lipid-rich necrotic nucleus [LRNC], intraplaque hemorrhage and fibrous cap surface rupture) and morphological parameters (lumen area [LA], wall area [WA], total area of blood vessels [TVA], plaque burden [PB]) was analyzed. Follow-up review analysis was conducted on 38 postoperative patients.

Results

Significant negative correlation was discovered between CS value and cognitive scores in CAS patients (R=-0.359, P<0.001), which did not exist in postoperative patients (P=0.348); CS value also showed significant correlation with WA (R=0.521, P=0.042), TVA (R=0.215, P=0.017) and PB (R=0.237, P=0.003) and had a certain predictive value for the occurrence probability of carotid plaque LRNC (P=0.029, AUC =0.780) in preoperative patients.

Conclusion

Carotid artery CSs have significant correlation with cognitive scores, which could be used as risk factor for early screening of cognitive impairment in CAS patients. The possible mechanism may be related to the calcification impact on the plaque burden.

Gamma prime (γ') fibrinogen and carotid intima-media thickness: the Atherosclerosis Risk in Communities study

: We assessed if γ' fibrinogen, an isoform of fibrinogen, is independently associated with subclinical atherosclerosis beyond total fibrinogen in black and white men and women participating in the Atherosclerosis Risk in Communities study. Fasting γ' fibrinogen was measured in 6847 Atherosclerosis Risk in Communities participants, ages 51-70 years, in 1993-1995. Carotid intima-media far wall thickness (CIMT) was measured by B-mode ultrasonography at the common, internal and bifurcation carotids. The association of γ' fibrinogen tertiles with overall and segment-specific mean CIMT was assessed with linear regression, controlling for fibrinogen as well as cardiovascular risk factors, including high-sensitivity C-reactive protein and D-dimer. γ' Fibrinogen values ranged from 8.0 to 80.3 mg/dl and were positively related to age, female sex, black race, smoking, BMI, lipids and SBP. Crude γ' fibrinogen was directly associated with all CIMT measures except for the internal carotid, but explained less than 1% of the variance in the associations. Adjustment for total fibrinogen eliminated these associations, and total fibrinogen remained an independent predictor of CIMT without explaining additional variance. Adjustment for potential confounding variables did not alter the observed associations, which did not differ by race or sex. In these cross-sectional data, γ' fibrinogen was not independently associated with CIMT when controlling for total fibrinogen. γ' Fibrinogen and total fibrinogen together explained a very small proportion of the variance in CIMT, regardless of the carotid site. If γ' fibrinogen adds to total fibrinogen's ability to predict subclinical atherosclerosis, it may be in younger populations.

Acoustic shadowing impairs accurate characterization of stenosis in carotid ultrasound examinations

OBJECTIVE

Duplex ultrasonography (DUS) has been the mainstay for diagnosing carotid artery stenosis and is often the sole diagnostic modality used prior to intervention. Highly calcified plaque, however, results in an acoustic shadow (AcS) that obscures the vessel lumen and inhibits the sonographer's ability to obtain Doppler velocity measurements. It is unknown whether DUS can accurately determine the degree of carotid stenosis in these settings.

METHODS

From July 2012 to December 2013, all patients with AcS on DUS measuring ≥5 mm in the longitudinal axis were cross-referenced with multidetector computed tomographic angiography (MD-CTA) images of the neck to define the study population. After standardizing the MD-CTA windows, percent stenosis was determined by cross-sectional area reduction using two separate previously described methods based on North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) criteria. DUS waveform parameters in the internal carotid artery near the AcS were then compared with these MD-CTA measurements to determine the accuracy of DUS in characterizing the severity of carotid stenosis.

RESULTS

During this period, 8517 DUS studies were performed at the Massachusetts General Hospital, 550 of which had AcS, for an incidence of 6.45%. There were 92 lesions with a concomitant MD-CTA; however, seven were excluded because of poor study quality, because ≥6 months had elapsed between DUS and MD-CTA, or because the patient had undergone carotid reconstruction between studies. Of the 85 remaining lesions, DUS characterized 17 as severe (peak systolic velocity [PSV] >250 cm/s), 31 as moderate (PSV = 151-250 cm/s), and 37 as mild (PSV ≤150 cm/s) stenoses using PSV criteria. PSV weakly correlated with CTA-NASCET (r = 0.361; P = .004) and CTA-ECST (r = 0.306; P = .004) percent stenosis. Using PSV >250 cm/s as the predictor of >70% stenosis, and a ≥70% cutoff by both CTA-ECST and CTA-NASCET methods as the reference measure, DUS sensitivity ranged from 22.7% to 32.5%, specificity from 89.4% to 91.1%, positive predictive value from 88.2% to 76.4%, and negative predictive value from 25% to 60.2%. A subgroup analysis of lesions identified as non-severe by DUS revealed that waveforms with lower deceleration were associated with severe stenosis on CTA.

CONCLUSIONS

In the presence of AcS, DUS alone is inadequate to accurately determine the degree of carotid stenosis with sensitivity, specificity, and negative predictive values far below that needed for clinical decision-making. MD-CTA may be necessary for improved characterization of plaque in these AcS lesions. Further studies are needed to determine DUS parameters that may identify patients who should undergo further evaluation with MD-CTA to characterize the true severity of the stenosis.

Middle Cerebral Artery Calcification: Association With Ischemic Stroke

Calcification of the middle cerebral artery (MCA) is uncommon in the healthy elderly. Whether calcification of the MCA is associated with cerebral ischemic stroke remains undetermined. We intended to investigate the association using Agatston calcium scoring of the MCA. This study retrospectively included 354 subjects with ischemic stroke in the MCA territory and 1518 control subjects who underwent computed tomography (CT) of the brain. We recorded major known risk factors for ischemic stroke, including age, gender, hypertension, diabetes mellitus, smoking, hyperlipidemia, and obesity, along with the MCA calcium burden, measured with the Agatston calcium scoring method. Univariate and modified logistic regression analyses were performed to examine the association between the MCA calcification and ischemic stroke. The univariate analyses showed significant associations of ischemic stroke with age, hypertension, diabetes mellitus, smoking, total MCA Agatston score, and the presence of calcification on both or either side of the MCA. Subjects with the presence of MCA calcification on both or either side of the MCA were 8.46 times (95% confidence interval, 4.93-14.53; P < 0.001) more likely to have a cerebral infarct than subjects without MCA calcification after adjustment for the major known risk factors, including age, hypertension, diabetes mellitus, and smoking. However, a higher degree of MCA calcification reflected by the Agatston score was not associated with higher risk of MCA ischemic stroke after adjustment for the confounding factors and presence of MCA calcification. These results suggest that MCA calcification is associated with ischemic stroke in the MCA territory. Further prospective studies are required to verify the clinical implications of the MCA calcification.

High Agatston Calcium Score of Intracranial Carotid Artery: A Significant Risk Factor for Cognitive Impairment

The effect of intracranial internal carotid artery (ICA) calcification on cognitive impairment is uncertain. Our objective was to investigate whether intracranial ICA calcification is a significant cognitive predictor for cognitive impairment. Global cognition and degrees of intracranial ICA calcification of 579 subjects were assessed with Mini-Mental State Examination (MMSE) and Agatston calcium scoring method, respectively. Other risk factors for cognitive impairment, including age, education level, hypertension, diabetes mellitus, smoking, hyperlipidemia, and body mass index, were documented and analyzed for their associations with cognitive function. In univariate analyses, older age, lower education level, hypertension, diabetes mellitus, and higher intracranial ICA Agatston scores were significantly associated with cognitive impairment. In ordinal logistic regression, only age and total intracranial ICA Agatston score were significant risk factors for cognitive impairment. After adjustment for the other documented risk factors, subjects were 7% (95% CI: 5-10; P < 0.001) and 6% (95% CI: 0-13; P = 0.04) more likely to have lower cognitive category with every year increment of age and every 100-point increment of the total intracranial ICA Agatston score respectively. These results suggest an important role of the intracranial ICA calcification on cognitive impairment.

Occupational characteristics and the progression of carotid artery intima-media thickness and plaque over 9 years: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVES

The role of occupation in the development of cardiovascular disease (CVD) remains a topic of research because few studies have examined longitudinal associations, and because occupation can be an indicator of socioeconomic position (SEP) and a proxy for hazard exposure. This study examines associations of occupational category as an SEP marker and selected occupational exposures with progression of the subclinical carotid artery disease.

METHODS

A community-based, multiethnic sample (n=3109, mean age=60.2) provided subclinical CVD measures at least twice at three data collection points (mean follow-up=9.4 years). After accounting for demographic characteristics, SEP, and traditional CVD risk factors, we modelled common carotid intima-media thickness, carotid plaque scores, and carotid plaque shadowing as a function of occupational category, physical hazard exposure, physical activity on the job, interpersonal stress, job control and job demands. These job characteristics were derived from the Occupational Resource Network (O*NET). Random coefficient models were used to account for repeated measures and time-varying covariates.

RESULTS

There were a few statistically significant associations at baseline. After all covariates were included in the model, men in management, office/sales, service and blue-collar jobs had 28-44% higher plaque scores than professionals at baseline (p=0.001). Physically hazardous jobs were positively associated with plaque scores among women (p=0.014). However, there were no significant longitudinal associations between any of the occupational characteristics and any of the subclinical CVD measures.

CONCLUSIONS

There was little evidence that the occupational characteristics examined in this study accelerated the progression of subclinical CVD.

Imaging of functional and structural alterations of large arteries after acute ischaemic atherothrombotic stroke or acute coronary syndromes

BACKGROUND

Non-invasive methods allow the evaluation of structural and functional arterial abnormalities. So far, no study has focused on the comparison of vascular parameters by type of cardiovascular event.

METHODS

In this pilot study, cardiovascular risk factors, carotid parameters, carotid-to-femoral pulse wave velocity (PWV), brachial flow-mediated dilation and ambulatory blood pressure were assessed in patients who presented with acute coronary syndromes (ACS) or ischaemic atherothrombotic stroke (IAS). Groups were matched for age and gender.

RESULTS

Prevalences of hypertension, diabetes and dyslipidaemia and heredity, smoking and body mass index were similar in the ACS (n=50) and IAS (n=50) groups. Carotid intima-media thickness (IMT) and PWV were significantly higher in the IAS vs. ACS group (769±180 vs. 701±136 μm; P=0.039 and 12.5±3.5 vs. 10.7±2.4 m/s; P=0.006). Carotid distensibility was significantly lower in the IAS vs. ACS group (16.2±3.2 vs. 18.9±7.6 10(-3)/kPa; P=0.02). These differences persisted after adjustment for blood pressure for carotid distensibility but not for PWV. The prevalences of endothelial dysfunction and carotid plaques were not significantly different in the ACS and IAS groups (86% and 74%; 80% and 78%). In a multivariable model, carotid distensibility remained associated with ACS (odds ratio 1.19; 95% confidence interval 1.03-1.38; P=0.016).

CONCLUSIONS

Stiffness and carotid wall thickness were higher in IAS than in ACS patients. These differences may support the interest in new therapeutic targets for cardiovascular secondary prevention.

NCT NO

NCT00926874.

Carotid artery atherosclerosis among 65-year-old Swedish men - a population-based screening study

OBJECTIVE

There are limited contemporary epidemiological data on the prevalence of carotid atherosclerosis in the general population. The aim was to determine the prevalence of and risk factors associated with carotid artery atherosclerosis among 65-year-old men.

METHODS

This was a population-based screening study. All 65-year-old men in the County of Uppsala, Sweden, who attended screening for abdominal aortic aneurysm (AAA) 2007-2009, were invited for duplex scanning of the carotid arteries.

RESULTS

Of 4801 men invited, 4657 (97%) accepted. Carotid plaques (>2 × 6 mm) were observed in 1169 (25%) men, 94 (2.0%) had carotid stenoses (50-99%), and 15 (0.3%) had occluded carotid arteries. In a multivariate logistic regression model, smoking (OR 1.7, 95% CI 1.5-1.9), hypertension (1.5, 95% CI 1.3-1.7), diabetes mellitus (1.2, 95% CI 1.0-1.5), and coronary artery disease (1.5, 95% CI 1.3-1.8) were associated with prevalence of carotid atherosclerosis (plaque and/or stenosis). The use of antiplatelet agents and statins in participants with a carotid plaque was 20% and 29%, respectively. The corresponding figures in participants with a stenosis were 42% and 41%.

CONCLUSIONS

This study offers contemporary data on the prevalence of carotid atherosclerosis in a population-based cohort of 65-year-old men. Most of those at risk had no other clinical manifestation of atherosclerosis, and therefore had no secondary prevention.

Bilateral common carotid artery ultrasound for prediction of incident strokes using intima-media thickness and external diameter: an observational study

Background

External common carotid artery (CCA) diameter and intima-media thickness (IMT) are independently associated with incident stroke and other cardiovascular events. Arterial geometry such as large IMT and large diameter may reflect vulnerable plaques and so impact stroke risk. Finally, arterial changes that exist bilaterally may increase stroke risk.

Method

We studied middle-aged men and women (n=7276) from a prospective observational study who had right (R) and left (L) CCA IMT and external diameters measured via B-mode ultrasound (1987–89) in order to categorize CCA geometry. Using side- and gender-specific IMT and diameter medians, we categorized each measurement as large (≥ median) vs. not large (< median) and defined four geometries: both IMT and diameter were large, only one parameter was large, or neither was large (reference group). Participants were followed for first time stroke through December 31, 1999. We used proportional hazards models to assess associations between right and left CCA geometries with new stroke. We also calculated positive and negative likelihood ratios (+LR and -LR) for CCA bilateral phenotypes as a measure of diagnostic accuracy.

Results

Presence of both large CCA IMT and large diameter on one side was associated with strong stroke risk even after risk factor adjustment (men: RCCA hazard ratio [HR]=3.7 95% confidence interval [CI]=1.9-7.4; LCCA HR=2.4 95% CI=1.4-4.4; women: RCCA HR=4.0 95% CI=1.5-10.5; LCCA HR=5.7 95% CI=1.7-19.0). Presence of both large IMT and large diameter bilaterally was the strongest predictor of stroke identifying 64% of women and 44% of men who developed strokes. This phenotype showed potential for predicting stroke among individuals (women: +LR=3.1, 95% CI=2.6-3.8; men: +LR=2.3, 95% CI=1.8-2.8).

Conclusion

Bilateral carotid artery geometries may be useful for stroke risk prediction.

Association of leukocyte subtype counts with coronary atherosclerotic regression following pravastatin treatment

The purpose of this study was to clarify the relation between differential leukocyte counts and inhibition of the development of coronary atherosclerosis in patients with coronary artery disease. A 6-month prospective study was conducted in 84 patients treated with pravastatin. Plaque volume, as assessed by volumetric analysis using intravascular ultrasound, decreased significantly by 12.6% (p <0.0001 vs baseline) after treatment; furthermore, a corresponding decrease of total leukocyte count (8.9%, p <0.01 vs baseline) was seen. Change in plaque volume was correlated with changes in monocyte (r = 0.35, p = 0.002) and lymphocyte (r = 0.25, p = 0.03) counts but not with changes in neutrophil, eosinophil, or basophil counts. In a multivariate regression analysis with changes in serum lipids, traditional risk factors, and medications as covariates, the decrease in monocyte count was identified as an independent predictor of coronary plaque regression (beta coefficient 0.313, 95% confidence interval 0.089 to 0.353, p = 0.0014). No correlation was found between change in monocyte count and changes in any other lipid levels. This study demonstrated that monocyte count was the only leukocyte type significantly and independently associated with coronary atherosclerotic regression, even after adjustment for changes in any lipid levels. In conclusion, the decrease in monocyte count as a nonlipid-lowering effect of statins may be used as a novel marker of coronary atherosclerotic regression.

E-selectin and TFPI are associated with carotid intima-media thickness in stable IHD patients: the baseline findings of the MIAMI study

OBJECTIVE

MIAMI was a prospective multicenter clinical study designed to investigate the relationship between changes in carotid intima-media thickness (C-IMT) and those in the levels of circulating markers of inflammation, thrombosis and endothelial dysfunction. The study was performed in a group of stable coronary patients treated for two years with a moderate dosage of atorvastatin (20mg/day). In this paper the cross-sectional relationship between C-IMT and the same circulating markers of inflammation, thrombosis and endothelial dysfunction measured at baseline was investigated.

METHODS

Eighty-five subjects that had not used statins for at least two months were enrolled in the study. At time of enrollment, the levels of vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), E-selectin, interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-alpha, high-sensitivity C-reactive protein (hs-CRP), tissue factor (TF), tissue factor pathway inhibitor (TFPI), von Willebrand factor (vWF), fibrinogen, total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL), and triglycerides were measured, in parallel with C-IMT assessment.

RESULTS

In cross-sectional analyses, markers of endothelial perturbation (i.e. E-selectin) and TFPI were more strongly correlated with arherosclerotic burden than markers of inflammation. The baseline picture in this study indicates that E-selectin and TFPI are linked with atherosclerotic burden.

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.

Potential of free-form TFPI and PAI-1 to be useful markers of early atherosclerosis in a Japanese general population (the Suita Study): association with the intimal-medial thickness of carotid arteries

This study assessed markers of vascular endothelial cell dysfunction associated with early atherosclerosis in carotid arteries. We measured the plasma levels of free-form tissue factor pathway inhibitor (free TFPI), plasminogen activator inhibitor-1 (PAI-1), and von Willebrand factor (vWF) in 522 adults without cardiovascular disease enrolled in the Suita Study. For each sex, we analyzed the association of the degree of intimal-medial thickness (IMT) with hemostatic markers using logistic regression analysis considering potential confounding risk factors, including age, body mass index, lifestyle (current smoking and drinking), illness (diabetes mellitus and hyperlipidemia), systolic blood pressure, and antihypertensive drug use. The age-adjusted levels of free TFPI and PAI-1 were positively and independently associated with the degree of IMT for men. Even after adjustment for all confounding factors, the level of PAI-1 was positively associated with the degree of IMT. These results indicate that measurement of the levels of free TFPI and PAI-1 is a potentially useful tool for the detection of early atherosclerosis in men.

Genetic basis of variation in carotid artery plaque in the San Antonio Family Heart Study

BACKGROUND AND PURPOSE

In contrast to the commonly used quantitative marker of subclinical atherosclerosis, namely intima-media thickness, we investigated the extent to which the presence or absence of carotid artery plaque (CAP) was under genetic control.

METHODS

The study population consisted of 750 individuals distributed across 29 randomly ascertained extended Mexican American pedigrees who participated in the second examination cycle of the San Antonio Family Heart Study. Extracranial focal CAP was identified by B-mode ultrasound bilaterally in the internal carotid artery or the carotid bulb. Using a variance decomposition approach implemented in the SOLAR computer program, we performed genetic analysis on the discrete trait CAP (ie, liability to disease) using a threshold model. Covariates considered in the analysis included age, sex, diabetes, current smoking status, lipid levels, and markers of hypertension and obesity.

RESULTS

Fifty-one of 461 women and fifty-seven of 289 men with a mean age of 42.1 years had evidence of a plaque in the right and/or left carotid artery. The age- and sex-adjusted heritability (h(2)+/-SE) for CAP was significant (h(2)=0.28+/-0.15, P=0.01). Furthermore, after adjustment for additional covariates that contributed significantly to the model (P<0.05; diabetes, hypertension, body mass index, waist circumference, and smoking status), heritability remained significant (h(2)=0.23+/-0.15, P=0.03).

CONCLUSIONS

Our data indicate that after established cardiovascular risk factors are controlled for, the variation of the discrete trait CAP is under appreciable additive genetic influences.