High-resolution B-Mode Ultrasound Scanning Methods in the Atherosclerosis Risk in Communities Study (ARIC)

An Abbreviated Carotid Intima-Media Thickness Scanning Protocol to Facilitate Clinical Screening for Subclinical Atherosclerosis

BACKGROUND

Carotid intima-media thickness (CIMT) testing can assist with cardiovascular risk prediction; however, the requirement for rigorous, time-consuming protocols has limited it use in clinical practice.

METHODS

Bilateral images of the common carotid artery (CCA), bulb, and internal carotid artery segments were obtained using a comprehensive scanning protocol. Three abbreviated scanning protocols were evaluated for their ability to identify patients with increased CIMT (> or = 75th percentile).

RESULTS

Of 261 subjects, 134 (51.3%) had increased left or right CCA CIMT (CCA protocol), 136 (52.1%) had carotid plaque (plaque protocol), and 190 (72.7%) had plaque or at least one increased CCA CIMT (combination protocol). The area under the receiver-operator characteristic curves for the CCA (0.738) and combination protocols (0.692) were higher than the plaque protocol (0.625, P < .05). The combination protocol was 100% sensitive.

CONCLUSIONS

Compared with a comprehensive scanning protocol, plaque screening with measurement of far wall CCA CIMT identifies all patients with increased CIMT.

Patients at high risk for ischemic stroke: identification and actions

Atherosclerosis is a disease of chronic inflammation. It is diffuse, multisystemic and affects the vascular, metabolic and immune systems. The traditional evaluation of risk is based on methods of clinical and biological assessments, and conventional imaging. The existence of symptomatic disease and the number of symptomatic sites of atherothrombosis are critical factors in predicting the recurrence of major vascular events. However, these methods are insufficient to predict near-future episodes, above all in the individual standard clinical practice. Active treatment of modifiable risk factors such as hypertension, dyslipidemia and atrial fibrillation can reduce the number of patients who develop a stroke. There is considerable evidence suggesting that a substantial proportion of the population with high blood pressure receives insufficient treatment. More active treatment of this condition is probably the most efficient single measure. Lifestyle factors such as smoking, diet, physical inactivity and obesity contribute to the relatively high incidence of stroke. There is a need to incorporate new systemic markers and new investigation techniques in the future so as to identify the individuals at risk in the population and to administer more individualized intervention therapies.

Utility of non-high-density lipoprotein cholesterol versus other lipoprotein measures in detecting subclinical atherosclerosis in young adults (The Bogalusa Heart Study)

Direct comparative data on the utility of non-high-density lipoprotein (HDL) cholesterol versus low-density lipoprotein cholesterol, HDL cholesterol, triglycerides, apolipoprotein (apo) B, apo A-I, ratio to total cholesterol to HDL cholesterol, and ratio of apo B to apo A-I in detecting increased carotid intima-media thickness (IMT), a validated measurement of subclinical atherosclerosis, in asymptomatic younger adults are scant. This aspect was examined in 1,203 black and white subjects (71% white, 43% men) 24 to 43 years of age. In multivariate logistic regression analysis of each lipoprotein measurement (top quartile vs lower 3 quartiles specific for age, race, and gender) for detecting increased carotid IMT (top decile vs lower 9 deciles specific for age, race, and gender), only non-HDL cholesterol, total cholesterol/HDL cholesterol, and apo B emerged as significant correlates with respective odds ratios of 1.75 (95% confidence interval [CI] 1.10 to 2.78), 2.02 (95% CI 1.27 to 3.19), and 2.13 (95% CI 1.38 3.29), after adjusting for body mass index, systolic blood pressure, and other lipoprotein measurements. Regarding discriminating values of different lipoprotein measurements in detecting increased carotid IMT, area (c-value) under the receiver operating characteristic curve analysis for each lipoprotein measurement adjusted for age, race, gender, body mass index, and systolic blood pressure indicated that the c-value for non-HDL cholesterol (0.73) was similar to those for low-density lipoprotein cholesterol (0.76), total cholesterol/HDL cholesterol (0.72), apo B/apo A-I (0.71), and HDL cholesterol (0.70), but significantly (p <0.001) higher than that for apo A-I (0.69), triglycerides (0.64), and apo B (0.64). In conclusion, non-HDL cholesterol is as good as or better than other widely recommended lipoprotein measurements in the identification of subclinical atherosclerosis in young adults.

Relation of sleep-disordered breathing to carotid plaque and intima-media thickness

BACKGROUND

Sleep-disordered breathing (SDB) is associated with clinical cardiovascular disease (CVD), but its relation to subclinical atherosclerosis remains to be determined.

METHODS

We analyzed the cross-sectional associations of SDB, measured by the respiratory disturbance index (RDI), a hypoxemia index, and an arousal index, with carotid plaque and carotid intima-media thickness (IMT), measured by ultrasound. The sample included 985 participants in the Sleep Heart Health Study (mean age-62, median RDI-8.7) with no history of coronary heart disease and stroke, of whom 396 had evidence of a carotid plaque.

RESULTS

As compared with the first quartile of the RDI (0-1.2), the crude odds ratio for carotid plaque was 1.14, 1.27, and 1.48 for the second (1.3-4.1), third (4.2-10.7), and fourth (>10.7) quartile, respectively. After adjustment for CVD risk factors, the corresponding odds ratios were reduced (1.00, 1.04, 1.07, and 1.25). Similarly, the unadjusted mean carotid IMT increased with RDI, but adjusted means (mm) were similar (0.84, 0.85, 0.84, 0.85). Spline regression models did not show monotonicity of the dose-response functions at the right end of the RDI distribution. Neither the hypoxemia index nor the arousal index was associated with carotid plaque or carotid IMT.

CONCLUSION

The results of this study suggest that crude, positive associations between SDB and subclinical atherosclerosis can be attributed to confounding by CVD risk factors.

Predictors of Carotid Intima-Media Thickness Progression in Young Adults

Background and Purpose— We sought to evaluate the predictors of carotid intima-media thickness (CIMT) progression in young adults and to determine whether they differed between the sexes. Although risk factors for the progression of atherosclerosis in middle-aged and elderly adults are well known, they are less well understood in young adults. CIMT is a validated measure of subclinical atherosclerosis.

Methods— B-mode ultrasound images of the far walls of both carotid arteries were obtained in 336 young adults in the Bogalusa Heart Study, whose mean±SD age was 32.3±3.0 years. CIMT and risk factors were measured at baseline (1995–1996) and after 5.8±0.6 years. Multivariable regression was used to determine the predictors of CIMT progression.

Results— CIMT progression rates in women (0.015±0.024 mm/y) and men (0.020±0.027 mm/y) were not statistically different after controlling for body mass index ( P =0.155). Smoking was a statistically significant predictor of common and composite CIMT progression in both sexes. In men, systolic blood pressure was an independent predictor of internal carotid and composite CIMT progression, fasting glucose predicted common CIMT progression, and family history predicted composite CIMT progression.

Conclusions— In young adults, smoking was a consistent predictor of short-term CIMT progression in men and women. Traditional risk factors also predicted CIMT progression in men.

Race (black-white) and gender divergences in the relationship of childhood cardiovascular risk factors to carotid artery intima-media thickness in adulthood: the Bogalusa Heart Study

It has been established that childhood cardiovascular (CV) risk factors are predictive of adulthood vascular changes as measured by carotid intima-media thickness (IMT). However, whether this relationship is race- and gender-specific is not known. This aspect was examined in a black-white cohort of 868 adults (29% blacks, 42% males) aged 25-44 years who were examined at least twice in childhood for traditional CV risk factors with an average follow-up period of 26.4 years. The average value of the two earliest childhood measurements was used as the childhood value, standardized to age, race, and gender-specific z-score. Carotid IMT was measured by B-mode ultrasonography. The mean of the maximum carotid IMT readings of three right and three left far walls for common, bulb and internal segments was used. In univariate analysis, significant correlates of adulthood carotid IMT (standardized to age-, race- and gender-specific z-score) were, in the order of decreasing magnitude, triglyceride and LDL cholesterol in white males; systolic blood pressure, LDL cholesterol, and body mass index (BMI) in white females; systolic blood pressure in black males; BMI and systolic blood pressure in black females. In multivariate regression analysis, significant predictors of carotid IMT were triglycerides and LDL cholesterol in white males; systolic blood pressure and LDL cholesterol in white females; systolic blood pressure in black males; and BMI and LDL cholesterol in black females. In conclusion, the predictability of childhood CV risk factors for increased carotid IMT in adulthood varies by race and gender. The prevention implications of these findings need further investigation.

Establishment of a high sensitivity plasma assay for human pentraxin3 as a marker for unstable angina pectoris

OBJECTIVE

Plasma pentraxin 3 (PTX3) levels are increased in patients with acute myocardial infarction, yet its involvement in unstable angina pectoris (UAP) remains unclear. To critically evaluate the role of PTX3 in UAP, a sensitive and precise measurement of PTX3 concentration is needed.

METHODS AND RESULTS

We established a high sensitive plasma ELISA assay system for the detection of PTX3 using monoclonal antibodies. The lower limit of detection of our ELISA was 0.1 ng/mL, sensitivity far greater than the current commercially available kit. Plasma samples were obtained from 162 consecutive patients treated for hypertension, hyperlipidemia, diabetes mellitus, or cardiovascular disease at a physician's office. PTX3 was not associated with any known coronary risk factors. Additionally, we collected plasma samples from 252 consecutive subjects admitted to a university hospital for coronary artery assessment by coronary angiography. PTX3 was significantly increased in patients in whom coronary intervention was performed. We further analyzed the plasma level of PTX3 in 52 patients with effort angina (EAP) and 16 patients with UAP. Compared with the control group, PTX3 were significantly higher in the UAP group.

CONCLUSIONS

The levels of plasma PTX3 were increased in patients with arterial inflammation, especially UAP. This PTX3 detection system will be useful for the prediction of UAP.

Adult-onset asthma is associated with increased carotid atherosclerosis among women in the Atherosclerosis Risk in Communities (ARIC) study

Some studies have suggested that asthma may be a risk factor for coronary heart disease and stroke, particularly in women. Child and adult-onset asthma differ according to inflammatory characteristics and gender distribution. We examined whether childhood-onset and adult-onset asthma were associated with carotid artery intima-media thickness (IMT) in men and women in the Atherosclerosis Risk in Communities (ARIC) study. In unadjusted analyses, the weighted mean far wall IMT thickness for women with history of adult-onset asthma was significantly greater than that of women without history of asthma (0.731 mm versus 0.681 mm; p<0.0001) while IMT for women with history of childhood-onset asthma (IMT=0.684 mm) did not differ substantially from non-asthmatic women. Mean IMT did not differ significantly according to asthma history among men. When the data were fitted to a linear model, the interaction between asthma status and gender was significant (p=0.006). After adjusting for age, race, BMI, smoking status, smoking pack years, diabetes, hypertension, physical activity, education level, and high and low density lipoprotein levels, the mean IMT difference between women with adult-onset asthma and no history of asthma was attenuated but remained significant (0.713 mm versus 0.687 mm, p=0.008). In conclusion, adult-onset asthma but not child-onset asthma is associated with increased carotid atherosclerosis among women but not among men.

Cumulative socioeconomic status across the life course and subclinical atherosclerosis

PURPOSE

The purpose of this study is to investigate the relationship between individual-level and neighborhood-level socioeconomic status (SES) across the life course and subclinical atherosclerosis.

METHODS

Participants from the Atherosclerosis Risk in Communities Study (n=12,332) were queried about individual-level SES and residential addresses across the life course. Individual-level measures were scored and summed to obtain a summary score (I-CumSES), whereas residential addresses were geocoded and linked to census data to obtain a summary neighborhood z score (N-CumSES) to evaluate the association of SES with intima-media thickness (IMT) and peripheral arterial disease (PAD).

RESULTS

A 1-SD lower I-CumSES was associated with greater mean IMT in each race-sex group and greater odds of PAD in white men (odds ratio [OR], 1.28; 95% confidence interval [CI], 0.99-1.64), white women (OR, 1.18; 95% CI, 1.02-1.36), and black women (OR, 1.33; 95% CI, 1.00-1.76). Compared with the highest tertile of N-CumSES, the lowest tertile was associated with greater mean IMT among whites, but was not associated with PAD for whites or blacks. When I-CumSES and N-CumSES were considered simultaneously, associations remained for only I-CumSES and were attenuated after adjustment for cardiovascular disease (CVD) risk factors.

CONCLUSIONS

Lower cumulative individual-level SES across the life course was associated with a greater burden of subclinical atherosclerosis, and this association was mediated in part by CVD risk factors.

Cardiovascular risk among adults with chronic kidney disease, with or without prior myocardial infarction

OBJECTIVES

This study sought to determine whether chronic kidney disease (CKD) should be considered a coronary heart disease (CHD) risk equivalent for cholesterol treatment.

BACKGROUND

It is unclear whether patients with CKD have a risk of CHD events or cardiovascular disease (CVD) mortality equivalent to patients with a prior myocardial infarction (MI).

METHODS

Using data from the ARIC (Atherosclerosis Risk in Communities) study, we categorized nondiabetic participants based on their average level of kidney function (estimated glomerular filtration rate > or =60 or 30 to 59 ml/min/1.73 m2, which defines stage 3 CKD) and on prior MI (yes or no). Rates and relative risks (RR) of CHD (MI or fatal CHD) events (n = 653) and CVD mortality (n = 209) that occurred over 10 years were compared across these populations.

RESULTS

Among 12,243 middle-age participants, 271 had stage 3 CKD. After adjustment for age, gender, race, and center, CHD incidence and CVD mortality rates per 1,000 person-years by presence of CKD and MI were 4.1 and 1.0 in the presence of neither condition, 8.0 and 3.4 in CKD only, 18.8 and 7.0 in MI only, and 30.8 and 18.0 in CKD and MI. After further adjustment for CVD risk factors, RR of CHD and CVD mortality were statistically significantly lower in subjects with CKD and no prior MI (RR = 0.44 [95% confidence interval (CI) 0.28 to 0.72] for CHD and RR = 0.46 [95% CI 0.24 to 0.90] for CVD mortality) than for subjects with no CKD and a prior MI.

CONCLUSIONS

Stage 3 CKD confers CHD risk that is lower and not equivalent to a prior MI in this middle-aged, general, nondiabetic population.

High prevalence of metabolic syndrome in patients with ankylosing spondylitis

The objective of this work is to investigate the occurrence of atherosclerosis and metabolic syndrome (MetS) in ankylosing spondylitis (AS) patients (pts). Twenty-four consecutive AS pts (men, 87.5%; median age, 50.5 years; median disease duration, 16.5 years), fulfilling the modified 1984 New York criteria for AS criteria, and 19 age- and sex-matched controls were investigated. Clinical atherosclerosis was evaluated by physical examination for cardiovascular (CV) diseases and history or drug use for CV events. Subclinical atherosclerosis was detected by mean intima media thickness (a-IMT) and maximum IMT (max-IMT) of carotid arteries using ultrasonography. Laboratory investigations including fasting plasma glucose, total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides were assessed by standard methods, while homocysteine was assessed by chemiluminescence. MetS was assessed using the updated NCEP-ATP III criteria. Disease activity was defined according to the International Ankylosing Spondylitis Assessment Study criteria. The 10-year CV risk (%) profile was evaluated in agreement to the Progetto Cuore criteria. No major CV event was detected in the study population. No significant differences were found when AS pts and controls were compared according to the mean a-IMT (0.52+/-0.26 vs 0.51+/-0.13 mm), max-IMT (0.92+/-0.20 vs 0.85+/-0.39 mm), prevalence of abnormal max-IMT >1 mm (27.2 vs 5.3%), and 10-year CV risk (9.9+/-9.6 vs 3.6+/-1.8%). Systolic blood pressure (p=0.04), triglyceride to HDL cholesterol ratio (p=0.002), and LDL cholesterol (p=0.03) were found significantly higher in AS pts than in controls; on the contrary, HDL cholesterol was pointed out as significantly lower (p<0.001). MetS was found in 11/24 (45.8%) AS pts and in 2/19 (10.5%) controls (p=0.019). No significant relationship emerged in MetS prevalence among AS pts regarding the mean value of age, disease duration, Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Disease Activity Index, and the Italian version of Health Assessment Questionnaire. This preliminary report points out a higher prevalence of MetS in AS pts than in controls. Further studies are needed to confirm this finding.

Apolipoprotein E polymorphisms predict low density lipoprotein cholesterol levels and carotid artery wall thickness but not incident coronary heart disease in 12,491 ARIC study participants

Elevated levels of low density lipoprotein (LDL) cholesterol is a well-established risk factor for cardiovascular disease, and recent advancements have provided evidence that carotid artery intima-media thickness (IMT) is associated with increased occurrence of cardiovascular events. Apolipoprotein E (ApoE) has been widely studied in regard to its role in lipid transport and metabolism, but the role that ApoE genetic variation plays in relation to carotid artery IMT and risk of incident coronary heart disease remains a subject of debate. In 1987-2001, the authors examined the effect of each ApoE allele (epsilon2, epsilon3, epsilon4) on LDL cholesterol and carotid IMT, as well as the association with coronary heart disease risk, in 12,491 participants of the US Atherosclerosis Risk in Communities Study. ApoE epsilon2, epsilon3, and epsilon4 allele frequencies were determined, respectively, in Whites (0.08, 0.77, 0.15) and African Americans (0.11, 0.67, 0.22). These alleles did not predict incident coronary heart disease in either racial group. The ApoE epsilon2 allele was associated with lower LDL cholesterol and the epsilon4 allele with higher LDL cholesterol in both Whites and African Americans. The ApoE epsilon2 and epsilon4 alleles were associated with carotid IMT measures in both racial groups, but, after adjusting for lipid parameters, only the epsilon4 allele was associated with carotid IMT measures in African Americans.

Serum uric acid and risk of ischemic stroke: The ARIC Study

AIMS

Since serum uric acid (UA) is strongly associated with cardiovascular risk factors, it has been debated whether serum UA is a stroke risk factor or whether UA may be simply "marking" subjects with other, causal risk factors. We therefore investigated the relation between UA and ischemic stroke in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS AND RESULTS

Of 15,792 ARIC participants, 13,413 who were free of recognized stroke or coronary heart disease (CHD) at baseline and had a baseline UA measurement were included in the analysis. We followed the participants for ischemic stroke incidence (N=381) over 12.6 years. Although serum UA was independently and positively related to ischemic stroke incidence when we adjusted for age, sex, race, and education, the positive relation was weakened when additionally adjusted for possible confounding variables. The positive multivariate-adjusted association between serum UA and ischemic stroke was observed among subjects not using diuretics (adjusted relative hazard in the highest quartile versus the lowest: relative hazard (RH)=1.49; 95% confidence interval (CI): 1.00-2.23) (P for trend: 0.02), but not among diuretic users (P for interaction: 0.08).

CONCLUSION

Our findings suggest that UA is an independent predictor of ischemic stroke among subjects not using diuretics, but that elevated UA itself may not cause ischemic stroke.

Correlates of vascular structure and function measures in asymptomatic young adults: the Bogalusa Heart Study

BACKGROUND

Adverse changes in arterial structure and function, independent predictors of cardiovascular (CV) disease morbidity and mortality, are known to be associated with CV risk factors, especially in middle-aged and older adults. Although non-invasive studies in this regard are beginning to emerge in a younger age population, information is lacking on the correlates of measures of vascular structure and function obtained simultaneously by different non-invasive methods.

METHODS

In 518 black and white subjects (72% white, 44% male) aged 27-43 years, vascular structure and function were measured in terms of (1) carotid artery intima-media thickness (IMT), (2) aorta-femoral pulse wave velocity (af-PWV), and (3) pulsatile arterial function in terms of large (C1) and small (C2) artery compliances.

RESULTS

Blacks versus whites and males versus females had higher carotid IMT; blacks versus whites higher af-PWV; and blacks versus whites and females versus males lower C1 and C2. In a multivariate regression model, significant predictors in the order of entry into the model were systolic blood pressure, male gender, age, cigarette smoking, and LDL cholesterol for carotid IMT (R(2)=0.189); systolic blood pressure, homeostasis model assessment of insulin resistance (HOMA-IR), cigarette smoking, and age for af-PWV (R(2)=0.200); systolic blood pressure, female gender, and HOMA-IR for C1 (R(2)=0.258); and systolic blood pressure, female gender, age, diastolic blood pressure, cigarette smoking, triglycerides, and black race for C2 (R(2)=0.394).

CONCLUSION

In asymptomatic young adults, CV risk factors influence adversely measures of both structure and function of the vasculature to varying degrees, with small artery compliance showing maximum variance. As part of preventive cardiology, assessment of structure/function measures of the vasculature by simple non-invasive methods may be helpful in identifying early vascular damage in a high-risk young population group.

Clinical significance of a high ankle-brachial index: insights from the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

The clinical significance of a high ankle-brachial index (ABI), defined by the associated risk factor burden and ischemic risk, is largely unknown.

METHODS

Using data from the Atherosclerosis Risk in Communities Study, we categorized 14,777 participants into normal (ABI between 0.9 and 1.3) and high ABI groups (ABI>1.3, >1.4, and >1.5) and compared the risk factor profile and CVD event rates of the normal ABI group to each high ABI group.

RESULTS

The prevalence of high ABI was 5.5% for ABI>1.3, 1.2% for ABI>1.4, and 0.37% for ABI>1.5. Compared with participants with a normal ABI, those with ABI>1.3 had a lower prevalence of hypertension and current smoking. The ABI>1.3 group had a greater mean body mass index, but was characterized by fewer pack years of smoking and lower systolic and diastolic blood pressures than the normal ABI group. The prevalence of diabetes, left ventricular hypertrophy, claudication, and coronary heart disease and mean values of fibrinogen, factor VIII activity, von Willebrand factor, lipoprotein (a), and carotid and popliteal intimal-medial thickness were similar between the two ABI groups. The risk factor profiles of the ABI>1.4 and >1.5 groups were also not statistically significantly different from that of the normal ABI group. Over a mean follow-up time of 12.2 years, the age, sex, and race-adjusted CVD event rates per 1000 person years were 8.1 in the normal ABI group, 7.6 in the ABI>1.3 group, 7.6 in the ABI>1.4 group, and 7.4 in the ABI>1.5 group. The CVD event rates of the high ABI groups were similar to that of the normal ABI group.

CONCLUSION

Individuals with a high ABI are not characterized by a more adverse atherosclerosis risk factor profile and do not suffer greater CVD event rates than those with a normal ABI.

Sequence variations in PCSK9, low LDL, and protection against coronary heart disease

BACKGROUND

A low plasma level of low-density lipoprotein (LDL) cholesterol is associated with reduced risk of coronary heart disease (CHD), but the effect of lifelong reductions in plasma LDL cholesterol is not known. We examined the effect of DNA-sequence variations that reduce plasma levels of LDL cholesterol on the incidence of coronary events in a large population.

METHODS

We compared the incidence of CHD (myocardial infarction, fatal CHD, or coronary revascularization) over a 15-year interval in the Atherosclerosis Risk in Communities study according to the presence or absence of sequence variants in the proprotein convertase subtilisin/kexin type 9 serine protease gene (PCSK9) that are associated with reduced plasma levels of LDL cholesterol.

RESULTS

Of the 3363 black subjects examined, 2.6 percent had nonsense mutations in PCSK9; these mutations were associated with a 28 percent reduction in mean LDL cholesterol and an 88 percent reduction in the risk of CHD (P=0.008 for the reduction; hazard ratio, 0.11; 95 percent confidence interval, 0.02 to 0.81; P=0.03). Of the 9524 white subjects examined, 3.2 percent had a sequence variation in PCSK9 that was associated with a 15 percent reduction in LDL cholesterol and a 47 percent reduction in the risk of CHD (hazard ratio, 0.50; 95 percent confidence interval, 0.32 to 0.79; P=0.003).

CONCLUSIONS

These data indicate that moderate lifelong reduction in the plasma level of LDL cholesterol is associated with a substantial reduction in the incidence of coronary events, even in populations with a high prevalence of non-lipid-related cardiovascular risk factors.

Validation of a Carotid Intima-Media Thickness Border Detection Program for Use in an Office Setting

BACKGROUND

A unique semiautomated border detection program (BDP) designed for use on a personal computer was evaluated to determine whether: (1) carotid intima-media thickness (CIMT) measurements were bioequivalent to a reference laboratory; and (2) it would allow a novice (NOV) reader with no medical training to accurately and reproducibly measure CIMT.

METHODS

Far-wall CIMT was measured blindly and in duplicate by an experienced and NOV reader using BDP and by a reference laboratory.

RESULTS

Mean CIMT using BDP was bioequivalent to the reference laboratory (two 1-sided T-test, P < .05) with small absolute differences (experienced 0.011 +/- 0.004 mm, NOV 0.022 +/- 0.004 mm). Reproducibility was high, with small coefficients of variation when used by either the experienced (3.1%) or NOV (7.8%) reader.

CONCLUSION

CIMT measurements using BDP were accurate and reproducible. It was mastered easily by a NOV reader and appeared suitable for use in an office setting.

Socioeconomic differences in progression of carotid intima-media thickness in the Atherosclerosis Risk in Communities study

OBJECTIVE

To examine the association of socioeconomic factors with progression of carotid intimal-medial thickness (IMT) in middle-aged adults. Cross-sectional associations of IMT with socioeconomic status (SES) have been demonstrated in middle-aged cohorts. It is unclear whether these factors are associated with progression of IMT.

METHODS AND RESULTS

We examined IMT progression over 9 years among a middle-aged cohort of 12,085 black and white subjects free of cardiovascular disease recruited from 4 US sites participating in the Atherosclerosis Risk in Communities (ARIC) study. Baseline IMT was inversely related to SES among whites and blacks. Repeated measures regression models of IMT progression showed moderate inverse relationships of IMT progression with income in whites so that the difference in 5-year IMT progression rates between the highest and lowest categories was -11.5 microm (CI, -17.4 to -5.6). In contrast, among blacks, this gradient is reversed, with an 11.1 microm (CI, -0.1 to 22.3) difference in 5-year progression between highest and lowest income category. Generally, similar patterns were observed for other socioeconomic indicators. Patterns were not accounted for by baseline cardiovascular risk factors.

CONCLUSIONS

SES is inversely related to IMT progression in middle-aged whites but positively related to IMT progression among middle-aged blacks. These differences do not appear to be attributable to selective attrition or higher IMT among blacks at baseline.

Skin cholesterol content identifies increased carotid intima-media thickness in asymptomatic adults

BACKGROUND

A noninvasive assay to measure skin Tc recently has become available for use in the outpatient setting as a cardiovascular (CV) risk prediction tool. The purpose of this study was to determine whether skin tissue cholesterol content (skin Tc) levels are associated with increased carotid intima-media thickness (CIMT) after adjusting for known CV risk factors and Framingham CV risk.

METHODS

Consecutive patients without known vascular disease who were referred for determination of CIMT underwent B-mode ultrasonography of the carotid arteries and measurement of skin Tc using a noninvasive assay. Use of medications, cardiac risk factors, and Framingham 10-year CV risk were determined prospectively. Multivariable regression was used to determine predictors of increased CIMT.

RESULTS

Among 81 subjects, the mean (SD) age was 55.6 (7.7) years and the mean skin Tc was 95.9 (18.3) U. Carotid intima-media thickness was significantly higher among individuals in the highest quartile of skin Tc (0.87 vs 0.76 mm, P = .011). In multivariable analyses, skin Tc was associated with increased CIMT even after adjusting for age, sex, glucose, systolic blood pressure, total/high-density lipoprotein cholesterol ratio, and use of lipid-lowering therapy (odds ratio [OR] per 10-unit increase = 1.590, 95% CI 1.525-1.658, P = .031). Skin Tc also was associated with increased CIMT after adjustment for Framingham risk (OR = 1.341, 95% CI 1.302-1.380, P = .048).

CONCLUSIONS

Skin Tc is an easy-to-measure, noninvasive marker that can help identify subclinical atherosclerosis in asymptomatic middle-aged adults, even after controlling for risk factors and CV risk predicted by the Framingham model.

Ultrasound-detected carotid plaque as a screening tool for advanced subclinical atherosclerosis

BACKGROUND

There is great need for a simple, noninvasive tool that can be used in an office setting to screen for subclinical atherosclerosis. In patients referred for cardiovascular (CV) risk assessment, we evaluated the ability of ultrasound screening for carotid plaque to identify patients with advanced subclinical atherosclerosis.

METHODS

Consecutive asymptomatic patients without vascular disease referred by their physician for measurement of the ankle-brachial pressure index and carotid intima-media thickness (CIMT) were included. Carotid intima-media thickness was measured using the standardized ultrasound protocol from the Atherosclerosis Risk in Communities (ARIC) study. Advanced atherosclerosis was defined as CIMT > or = 75th percentile for age, sex, and race in ARIC.

RESULTS

The mean age of the 327 subjects was 55.4 years (SD 7.7 years). The 10-year Framingham CV risk was 5.1% (4.8%). In a multiple logistic regression model that included Framingham CV risk, ankle-brachial pressure index, and use of lipid-lowering medications, plaque presence significantly predicted advanced atherosclerosis (odds ratio 3.08, 95% CI 1.91-4.96, P < .001). In stepwise regression models that included age, body mass index, current tobacco use, family history of premature CV disease, fasting glucose, sex, systolic blood pressure, total/high-density lipoprotein cholesterol ratio, and use of antihypertensive and lipid-lowering medications, plaque presence independently predicted advanced atherosclerosis (P < .001).

CONCLUSION

Ultrasound detection of carotid plaque helped identify asymptomatic patients with advanced subclinical atherosclerosis. Screening for carotid plaque is easier than determination of CIMT and may help detect asymptomatic patients at increased CV risk.

Cardiovascular Risk Profile of Asymptomatic Healthy Young Adults with Increased Femoral Artery Intima-Media Thickness: The Bogalusa Heart Study

BACKGROUND

Femoral artery intima-media thickness (IMT), like carotid IMT, is a surrogate indicator of atherosclerotic coronary and peripheral vascular diseases in middle-aged and older adults. This study examined the cardiovascular disease risk profile of asymptomatic young adults with increased femoral artery IMT.

METHODS

Femoral artery IMT was measured by B-mode ultrasonography in 1080 black and white subjects (aged 24-43 years; 71% white, 43% male) enrolled in the Bogalusa Heart Study. Individuals in the top (n=54) versus bottom fifth (n=54) percentiles distribution of femoral IMT were compared for traditional cardiovascular risk factors profile. Univariate analysis compared the two groups, t-tests and chi tests were performed.

RESULTS

The top and bottom fifth percentiles of IMT differed with respect to age (P<0.001), systolic blood pressure (P<0.05), diastolic blood pressure (P<0.05), total cholesterol (P<0.01), low-density lipoprotein (LDL) cholesterol (P<0.001), non-high-density lipoprotein (HDL) cholesterol (P<0.01) and smoking status (P<0.01). In terms of prevalence of clinically defined traditional risk factors, individuals at the top versus bottom fifth percentile of IMT distribution had significantly higher prevalence of high LDL cholesterol (>OR=130 mg/dL), non-HDL cholesterol (>OR=160 mg/dL), and cigarette smoking. The odds ratio for individuals with three or more risk factors versus no risk factors having IMT in the top fifth percentile was 4.7 (P=0.01).

CONCLUSION

The observed adverse effect of cardiovascular risk factors on IMT of femoral artery, a surrogate measure of coronary and peripheral atherosclerosis, in asymptomatic young individuals underscores the need for risk factors profiling in early life. These observations have important implications in preventive medicine.

Increased subclinical atherosclerosis in young adults with metabolic syndrome: the Bogalusa Heart Study

OBJECTIVES

The purpose of this study was to investigate the association of metabolic syndrome (MetS) with subclinical atherosclerosis, determined by ultrasound carotid intima-media thickness (CIMT) measurements, in young adults.

BACKGROUND

Metabolic syndrome is associated with subclinical atherosclerosis and increased cardiovascular risk in older and middle-aged adults; however, these associations have not been studied among young adults.

METHODS

Non-diabetic subjects from Bogalusa Heart Study, a longitudinal study of atherosclerosis in young adults, underwent B-mode ultrasonography of the carotid arteries. Metabolic syndrome was defined with the National Cholesterol Education Program Adult Treatment Panel III (MetSNCEP) and World Health Organization (MetSWHO) definitions. CIMT and MetS associations were evaluated with multivariable regression and area under receiver-operator characteristic curve (AUC) analyses.

RESULTS

Of 507 subjects (29% black, 39% male, mean [SD] age 32 [3] years), 67 (13%) had MetSNCEP and 65 (13%) had MetSWHO. Common (mean = 0.70 [0.11] mm vs. 0.66 [0.08] mm, p = 0.002) and internal CIMT (0.72 [0.21] mm vs. 0.68 [0.12] mm, p = 0.020) were higher among those with MetS(NCEP) than those without MetS(NCEP). Common (0.69 [0.11] mm vs. 0.66 [0.08] mm, p = 0.020) and internal CIMT (0.73 [0.23] mm vs. 0.68 [0.12] mm, p = 0.012) also were higher among those with MetSWHO than those without MetSWHO. Composite CIMT increased with the number of MetS components present (MetSNCEP r = 0.997, p < 0.001; MetSWHO r = 0.946, p = 0.053). Metabolic syndromeNCEP (AUC = 0.557, 95% confidence interval [CI] 0.513 to 0.601) and MetSWHO (AUC = 0.539, 95% CI 0.495 to 0.584) both predicted composite CIMT > or =75th percentile.

CONCLUSIONS

In young adults, MetS is associated with increased atherosclerotic burden, and therefore, increased cardiovascular risk. These results support the importance of screening and early intervention in this population.

Glycemic control, atherosclerosis, and risk factors for cardiovascular disease in individuals with diabetes: the atherosclerosis risk in communities study

OBJECTIVE

Glycemic control (HbA(1c) [A1C]) is strongly associated with microvascular disease in individuals with diabetes, but its relation to macrovascular disease and atherosclerosis is less clear. This study examines the relationship between A1C, carotid intima-media thickness (IMT), and traditional cardiovascular risk factors in individuals with diabetes.

RESEARCH DESIGN AND METHODS

A cross-sectional study of 2,060 people with diagnosed and undiagnosed (unrecognized) diabetes in the Atherosclerosis Risk in Communities study was performed.

RESULTS

LDL and HDL cholesterol, plasma triglycerides, and waist-to-hip ratio were significantly associated with A1C after multivariable adjustment. African Americans with undiagnosed and diagnosed diabetes had significantly elevated A1C values compared with whites, even after adjustment for potentially confounding factors. There was a graded association between A1C and carotid IMT. In a fully adjusted model in individuals with undiagnosed diabetes, the odds ratio (OR) of being in the highest quartile of IMT versus the lowest was 2.46 (95% CI 1.16-5.03, comparing the highest quartile of A1C to the lowest). In people with diagnosed diabetes, the comparable OR was 2.62 (1.36-5.06).

CONCLUSIONS

This study identified several important associations between A1C and known risk factors for cardiovascular disease and suggested that A1C is independently related to carotid IMT. Chronically elevated glucose levels may contribute to the development of atherosclerosis in people with diabetes, independent of other risk factors.

Diagnosis and prevention of atherosclerotic cerebral infarction

Atherosclerotic disease accounts for approximately 25% of ischemic strokes. Atherosclerotic stroke is caused mainly by embolic events from the carotid artery bifurcation or the aortic arch, although intracranial thrombosis can occur, more often in African Americans, Asians, and diabetes patients. Primary prevention of stroke is critical for patients with risk factors for atherosclerosis, including hypertension, diabetes, smoking and hypercholesterolemia. Stroke can be prevented in patients with established atherosclerotic disease by identification and management of patients with carotid artery stenosis by non-invasive testing. Particular attention must be paid to patients with transient symptoms of brain ischemia.

Risk factors for cardiovascular event recurrence in the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

Numerous studies have identified risk factors and markers associated with incidence of cardiovascular disease (CVD). However, few studies have examined whether established risk factors, novel blood markers, carotid ultrasonography, or ankle-brachial index can predict recurrent CVD events.

METHODS AND RESULTS

We analyzed the relation of established risk factors and markers of atherosclerosis with the risk of recurrent CVD in 766 participants. Over a mean of 8.7 years of follow-up, 70 women and 243 men had a recurrent CVD event (85.3% coronary heart disease and 23.7% stroke). Adjusting for age and sex, this study found that established risk factors were associated with recurrent CVD events in the anticipated direction. Being in the highest (vs lowest) quartiles of lipoprotein (a), fibrinogen, white blood cells, and creatinine at baseline were associated with 47%, 69%, 65%, and 81%, respectively, greater risk of a CVD event, and being in the highest quartile of albumin was associated with 39% lower risk. Being in the highest (vs lowest) quartile of carotid intima-media thickness (IMT) was associated with a doubling of risk, and having carotid plaque with acoustic shadowing (vs having no plaque) was associated with 83% increased risk of a CVD event. After adjustment for established risk factors, creatinine, albumin, and carotid IMT in the highest quartile (vs lowest quartile) and carotid plaque with acoustic shadowing (vs no plaque) were independently associated with recurrent CVD events.

CONCLUSION

Established risk factors, but only a few of novel risk factors and markers, were independent predictors of recurrent CVD events.

Q192R polymorphism of the paraoxanase 1 gene and its association with serum lipoprotein variables and carotid artery intima-media thickness in young adults from a biracial community. The Bogalusa Heart Study

Paraoxanase (PON 1), a high-density lipoprotein-associated enzyme, exerts an antiatherogenic effect by protecting low-density lipoproteins (LDL) against oxidation. A common polymorphism at codon 192(Q/R) of the PON 1 gene has been shown to be associated with an adverse lipoprotein profile and increased coronary artery disease (CAD) risk. However, these observations are based mostly on case-control studies involving relatively older adults. This study examined the frequency and phenotypic (lipoprotein variables) effect of the Q192R variant in a community-based sample of 1786 black and white young adults (mean age: 32.5 years; 69% white, 44% males). In addition, the genotypic effect of this polymorphism on ultrasonographically measured carotid artery intima-media thickness (IMT), a surrogate measure of CAD risk, was examined in a subsample of 436 young adults (mean age: 32.6 years; 70% white, 42% male). The frequency of the variant allele (R192) was higher in blacks than in whites (0.668 versus 0.297, P <0.001). After adjusting for age, sex, body mass index, and smoking status, the R versus Q allele was associated with increased HDL cholesterol in whites (P=0.041), whereas the opposite was true in blacks (P=0.008). Neither the Q nor the R allele was associated with LDL cholesterol and triglycerides in both races. The genotypic effect on the carotid IMT adjusted for the covariates including lipoprotein variables was not apparent in whites or blacks. However, among whites, the carotid IMT was lower in carriers (QR + R) versus non-carriers (QQ) of the variant allele among females (P=0.008) and non-smokers (P=0.026). In addition, the variant allele negated the adverse positive relationship between the carotid IMT and triglycerides among whites (P=0.212 for carriers versus P <0.001 for non-carriers). These results indicate a differential effect of the Q192R variant on HDL cholesterol in whites versus blacks and a beneficial interaction effect of the variant allele with individual's sex, smoking status or triglyceride levels on the carotid IMT among whites.

A semiautomated ultrasound border detection program that facilitates clinical measurement of ultrasound carotid intima-media thickness

We have developed a novel, semiautomated carotid intima-media thickness (CIMT) border detection program (AUTO) and evaluated its measurement reproducibility and accuracy. Images from 6 carotid segments were acquired in 50 subjects, for a total of 300 segments. Mean and maximum CIMT values were measured blindly at a reference (REF) lab and in duplicate by experienced (EXP) and novice (NOV) readers using manual (MAN) and AUTO methods. Coefficients of variation for AUTO measurements of mean (3.2%) and maximum (4.1%) CIMT were low, and the AUTO method improved the NOV reader's reproducibility. Compared with the REF lab, mean (0.012 +/- 0.006 mm) and maximum (0.144 +/- 0.006 mm) CIMT biases were small and equivalent to those of the REF lab ( P < .001). The AUTO method shortened reading times by 35% to 46% ( P < .001). We conclude that our novel AUTO CIMT measurement program improved reproducibility and was accurate. Compared with MAN tracing, the AUTO method agreed better with the REF lab and decreased reading time.

Impact of multiple cardiovascular risk factors on femoral artery intima-media thickness in asymptomatic young adults (the Bogalusa Heart Study)

Femoral artery intima-media thickness (IMT), like carotid IMT, is a surrogate indicator of atherosclerotic coronary and peripheral vascular diseases in middle-aged and older adults. Although risk factors for coronary artery disease are also associated with increased IMT, especially as measured in carotid arteries, there is a paucity of information with respect to the femoral artery in this regard in the asymptomatic, younger adult population. This study examined the impact of multiple risk factors on the common femoral artery IMT as measured by B-mode ultrasonography in 1,080 black and white subjects aged 24 to 43 years (71% white and 43% men) enrolled in the Bogalusa Heart Study. Femoral IMT showed gender difference (men more than women, p = 0.001), but no racial difference. In a multivariate model, systolic blood pressure, age, male gender, cigarette smoking, and total cholesterol/high-density lipoprotein cholesterol ratios related independently, in that order, to IMT. Mean IMT increased with an increasing number of risk factors defined as values above the age-, race-, and gender-specific 75th percentile of systolic blood pressure, waist circumference, total cholesterol/high-density lipoprotein cholesterol ratio, and insulin along with smoking status (p for trend = 0.003), with respective mean IMT values of 0.66, 0.69, 0.73, and 0.79 mm for 0, 1 to 2, 3, and 4 to 5 risk factors. The odds ratio for patients with >/=3 risk factors versus no risk factors having IMT in the top fifth percentile was 4.7 (p = 0.01). The observed adverse trend of increasing femoral IMT with an increasing number of risk factors in free-living, asymptomatic young subjects underscores the need for multiple risk factors profiling in early life. Further, ultrasonography of the femoral artery in conjunction with multiple risk factor profiling can be helpful in risk stratification.

Association of traditional and nontraditional cardiovascular risk factors with coronary artery calcification

Coronary artery calcification assessed by computed tomography is an emerging marker of coronary atherosclerosis. The authors examined the association of coronary calcium scores with traditional and nontraditional cardiovascular risk factors. In 1999-2000, they measured coronary artery calcium in 360 participants free of known coronary artery disease who had participated in 2 centers of the Atherosclerosis Risk in Communities (ARIC) Study. They related coronary calcium scores to risk factors measured in 1987-1989. Most traditional risk factors were associated with the coronary calcium score. For example, the multivariately adjusted odds ratio for an elevated score (> or = 100 versus < 100) was 3.5-fold greater per 10 years of age, 3.2-fold greater in men than in women, 3.1-fold greater with diabetes (statistically nonsignificant), and 1.4- to 1.7-fold greater per standard deviation greater increments of plasma cholesterol and pack-years of cigarettes smoked. Carotid artery intima-media thickness also was positively associated with coronary calcification. In contrast, a wide variety of hemostatic and inflammatory markers and serum chemistry values were unrelated to calcium scores. These findings reaffirmed the established role of traditional risk factors in the etiology of coronary artery disease, as assessed by computed tomography, but did not identify any important nontraditional risk factors.

Risk factors for peripheral arterial disease incidence in persons with diabetes: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Some risk factors for peripheral arterial disease (PAD) have been identified, but little information is available on PAD risk factors in individuals with diabetes.

METHODS

Using data from the Atherosclerosis Risk in Communities (ARIC) Study, we assessed the relation of traditional and non-traditional risk factors with the risk of PAD in 1651 participants with diabetes, but not PAD, at baseline. Incident PAD was defined as an ankle-brachial index (ABI)<0.9 assessed at regular examinations; hospital discharge codes for PAD, amputation, or leg revascularization; or claudication assessed by annual questionnaire.

RESULTS

Over a mean of 10.3 years of follow-up, 238 persons developed incident PAD identified, yielding a PAD event rate of 13.9 per 1000 person years. Adjusted for sex, age, race, and center, the risk of developing PAD was increased 1.87-fold (95% confidence interval (95% CI): 1.36-2.57) in persons who were current smokers versus non-smokers, 2.27-fold (95% CI: 1.57-3.26) for baseline coronary heart disease (CHD) versus no baseline CHD, and 1.75-fold (95% CI: 1.18-2.60) for the highest quartile versus lowest quartile of triglycerides. We found no evidence of an association with other blood lipids or hypertension. Compared with the lowest quartiles, comparably-adjusted relative risks for the highest quartiles were 1.60 (95% CI: 1.10-2.33) for waist-to-hip ratio, 2.52 (95% CI: 1.70-3.73) for fibrinogen, 1.70 (95% CI: 1.17-2.47) for factor VIII, 1.73 (95% CI: 1.18-2.54) for von Willebrand factor, 2.15 (95% CI: 1.43-3.24) for white blood cell count, 1.81 (95% CI: 1.19-2.74) for serum creatinine, 0.55 (95% CI: 0.37-0.83) for serum albumin, and 2.73 (95% CI: 1.77-4.22) for carotid intima-media thickness. Persons who had a prior history of diabetes and were taking insulin had a relative risk of 1.97 (95% CI: 1.35-2.87) for future PAD events, compared with those with newly identified diabetes at baseline. In our final multivariable model, current smoking, prevalent CHD, elevated fibrinogen and carotid IMT, and a prior history of diabetes with insulin treatment were independently associated with greater PAD incidence.

CONCLUSION

These markers might be useful to identify individuals with diabetes at particular risk for PAD.

The relation between birth weight and intima-media thickness in middle-aged adults

BACKGROUND

Birth weight has been found to be inversely associated with the risk of coronary heart disease and stroke, although the mechanisms for this association remain unclear. Here, we investigate the relation between reported birth weight and atherosclerosis in middle age.

METHODS

We included the 9817 participants (age 44-65) in the Atherosclerosis Risk in Communities (ARIC) study who were neither a twin nor born prematurely. Carotid atherosclerosis was assessed as intima-media thickness measured by B-mode ultrasound. We studied the association with recalled exact birth weight, and for those unable to recall exact birth weight, with recalled birth weight category.

RESULTS

Mean intima-media thickness (+/- standard deviation) was 0.73 +/- 0.17 mm. Mean birth weight for the 4635 participants recalling exact birth weight was 3.49 +/- 0.71 kg. A further 4946 participants recalled birth weight category, with 4730 (96%) reporting "medium" birth weight. In univariate analysis, birth weight and intima-media thickness were positively related. However, adjustment for confounding factors reduced the association to only a 0.004 mm higher intima-media thickness (95% CI = - 0.003 to 0.011) mm per 1 kg of birth weight. The same pattern of univariate positive relationship and attenuation with adjustment was seen for birth weight category and intima-media thickness. There was no evidence of interaction between adult body mass index (BMI) and birth weight, or of interaction between category of adult BMI and birth weight category. An inverse relation between birth weight category and intima-media thickness was seen only for those in the lowest category of adult BMI (BMI <25 kg/m).

CONCLUSIONS

We found no evidence of a clinically significant relation between birth weight and carotid atherosclerosis.

Heritability of Carotid Artery Atherosclerotic Lesions

Background and Purpose— Ultrasound examination of the carotid arteries yields several quantitative measures that may serve as intermediate phenotypes in genetic studies. This study was undertaken to compare the heritabilities of 3 ultrasound measures: intima-media thickness (IMT), plaque score, and maximal stenosis.

Methods— We studied 565 individuals from 154 families ascertained by an affected parent with carotid artery atherosclerosis. IMT, plaque score, and maximal stenosis of the carotid arteries were examined by B-mode ultrasound and analyzed quantitatively. Heritability estimates were obtained by variance component analysis as implemented in the program SOLAR (sequential oligogenic linkage analysis routines). Covariates were age, sex, weight, height, body mass index (BMI), arterial hypertension, diabetes mellitus, amount of nicotine consumed, and plasma levels of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, LDL/HDL ratio, lipoprotein(a) [Lp(a)], triglycerides, factor VIII, factor XIII, fibrinogen, and von Willebrand factor (vWF).

Results— After accounting for the covariables age, sex, hypertension, diabetes mellitus, and Lp(a), heritability of IMT was estimated as h 2 =0.61±0.17 ( P =0.001). Variation of plaque score was influenced by age, sex, hypertension, diabetes mellitus, hypercholesterolemia, amount of nicotine consumed, factor VIII, and vWF. When these were considered, no significant heritability could be detected. Heritability of stenosis was estimated as h 2 =0.47±0.07 ( P =0.006), with age, sex, BMI, hypertension, diabetes mellitus, amount of nicotine consumed, and LDL/HDL ratio as covariates.

Conclusions— Among the 3 ultrasound measures studied, IMT had the highest heritability. IMT was strongly influenced by genetic determinants other than those influencing known risk factors. This makes IMT a promising candidate for use as an intermediate phenotype in genetic studies aiming to identify novel genes for atherosclerosis.

Vascular age: integrating carotid intima-media thickness measurements with global coronary risk assessment

BACKGROUND

An imaging test that quantifies atherosclerotic burden and that can be integrated with existing risk stratification paradigms would be a very useful clinical tool.

HYPOTHESIS

Measurement of carotid intima-media thickness (CIMT) is feasible in a clinical setting. Such measurements can be integrated into coronary risk assessment models.

METHODS

Carotid intima-media thickness was measured by B-mode ultrasound in 82 consecutive patients without manifest atherosclerotic vascular disease. The values were used to determine "vascular age" (VA) based on nomograms from the Atherosclerosis Risk in Communities study. Vascular age was substituted for chronological age and standard and vascular age-adjusted 10-year coronary heart disease (CHD) risk estimates were compared.

RESULTS

The mean chronological age was 55.8 +/- 9.0 years. The mean VA using CIMT was 65.5 +/- 18.9 years (p < 0.001). The Framingham 10-year hard CHD risk estimate was 6.5 +/- 4.9%. Substituting CIMT-derived VA for chronological age increased the 10-year CHD risk estimate to 8.0 +/- 6.8% (p < 0.001). Of 14 subjects initially at intermediate risk, 5 (35.7%) were reclassified as higher risk and 2 (14.3%) were reclassified as lower risk. Significant predictors of reclassification were tobacco use, high-density lipoprotein cholesterol, systolic blood pressure, and low-density lipoprotein cholesterol.

CONCLUSIONS

Measurement of CIMT, a noninvasive estimate of current atherosclerotic burden, is feasible in a clinical setting and can be integrated into CHD risk assessment models. Determining VA using CIMT values may help individualize the age component of population-based CHD risk estimates. This strategy should be tested in a large trial with hard clinical endpoints.

Distribution and cross-sectional age-related increases of carotid artery intima-media thickness in young adults: the Bogalusa Heart Study

BACKGROUND AND PURPOSE

Reference values and age-related changes of carotid intima-media thickness (CIMT) have not been described in a community-based sample of young asymptomatic adults. CIMT measurements from the Bogalusa Heart Study, a study of the natural history of atherosclerosis in young adults and children, were used to characterize age-, race-, and sex-specific CIMT distributions and yearly rates of change.

METHODS

Age-, sex-, and race-specific CIMT percentile values and cross-sectional changes with age were estimated using B-mode carotid ultrasound images from 519 young adults (mean age 32 years, 61% female, 29% black). Nomograms of CIMT percentiles between the ages of 25 and 40 years are provided in 5-year increments.

RESULTS

CIMT was thickest in the carotid bulb and increased linearly with age, most rapidly in the bulb. With age, composite CIMT increased most slowly in white females and most rapidly in white males. Sample size estimates projected that 268 to 462 subjects are needed to detect CIMT changes > or =0.010 mm/year.

CONCLUSIONS

These estimated CIMT distributions and percentiles can serve as reference values for assessment of subclinical atherosclerosis in young adults. The observed age-related differences in CIMT can be used to plan epidemiological and clinical trials investigating atherosclerosis and anti-atherosclerotic interventions.

Measurement of arterial wall thickness as a surrogate marker for atherosclerosis

Large observational studies and atherosclerosis regression trials of lipid-modifying pharmacotherapy have established that intima-media thickness of the carotid and femoral arteries, as measured noninvasively by B-mode ultrasound, is a valid surrogate marker for the progression of atherosclerotic disease. To exploit fully the potential of ultrasound imaging in atherosclerosis research, standardized and strictly implemented imaging protocols should be used in both observational studies and applied clinical research. This article describes such a protocol developed at the Academic Medical Center of the University of Amsterdam, the Netherlands. Results are presented from a study that estimated atherosclerosis progression from childhood into old age by measuring intima-media thickness in subjects with familial hypercholesterolemia compared with healthy controls.

Laboratory, reading center, and coordinating center data management methods in the Jackson Heart Study

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in the United States. In comparison to whites, African-Americans have a higher risk of dying from CVD and have a worse risk factor profile. The Jackson Heart Study (JHS) is designed to investigate the origin and natural history of CVD in African-Americans.

METHODS

Reading centers for electrocardiograms, echocardiograms, carotid ultrasonograms, pulmonary function tests, and ambulatory blood pressure monitoring provide training for data accrual, quality assurance assessments, and specialized measurements for research objectives. Laboratories adhering to well-established quality assurance programs provide blood and urine analyses, as well as storage of specimens for future assays. A new Coordinating Center was created to perform functions analogous to those of coordinating centers for multisite studies, including protocol development, data management, statistical analyses, and operational support for the study. An established coordinating center serves as a resource to the JHS Coordinating Center, providing assistance in preparing procedure manuals and data collection forms. This group also designed and developed the JHS data management system.

RESULTS

This network of specialized research organizations is implementing state- of-the-science methodologies to assess prevalence, progression, and incidence of CVD and subclinical atherosclerosis, and to evaluate a myriad of risk factors. From November 2000 through March 2004, JHS collected 4000 data fields on each of more than 5300 African-American participants.

CONCLUSIONS

This article describes the roles of specialized research agencies contributing to JHS, and the methodologies being utilized to accumulate study data. A diverse collection of scientific disciplines is required to collect the information needed to meet the objectives of the JHS.

Heart rate-corrected QT interval prolongation predicts risk of coronary heart disease in black and white middle-aged men and women: the ARIC study

OBJECTIVES

We aimed to study the predictive value of heart rate-corrected QT interval (QTc) for incident coronary heart disease (CHD) and cardiovascular disease (CVD) mortality in the black and white general population, and to validate various QT measurements.

BACKGROUND

QTc prolongation is associated with higher risk of mortality in cardiac patients and in the general population. Little is known about the association with incident CHD. No previous studies included black populations.

METHODS

We studied the predictive value of QTc prolongation in a prospective population study of 14,548 black and white men and women, age 45 to 64 year. QT was determined by the NOVACODE program in the digital electrocardiogram recorded at baseline.

RESULTS

In quintiles of QTc, cardiovascular risk profile deteriorated with longer QTc, and risk of CHD and CVD mortality increased. The high risk in the upper quintile was mostly explained by the 10% with the longest QTc. The age-, gender-, and race-adjusted hazard ratios for CVD mortality and CHD in subjects with the longest 10% relative to the other 90% of the gender-specific QTc distribution were 5.13 (95% confidence interval 3.80 to 6.94) and 2.14 (95% confidence interval 1.71 to 2.69), respectively. The increased risk was partly, but not completely, attributable to other risk factors or the presence of chronic disease. The association was stronger in black than in white subjects. Manual- and machine-coded QT intervals were highly correlated, and the method of rate correction did not affect the observed associations.

CONCLUSIONS

Long QTc is associated with increased risk of CHD and CVD mortality in black and white healthy men and women.

Cardiovascular events in diabetic and nondiabetic adults with or without history of myocardial infarction

BACKGROUND

Whether diabetic patients without a history of myocardial infarction (MI) have the same risk of coronary heart disease (CHD) events as nondiabetic patients with a history of MI remains controversial. We compared risks of CHD and stroke events and mortality from cardiovascular disease (CVD) in diabetic and nondiabetic men and women with and without a history of MI.

METHODS AND RESULTS

We followed a total of 13 790 African American and white men and women ages 45 to 64 years who participated in the Atherosclerosis Risk in Communities study, beginning in 1987 to 1989. There were 634 fatal CHD or nonfatal MI events, 312 fatal or nonfatal strokes, and 358 deaths from CVD during an average of 9 years of follow-up (125 998 person-years). After adjustment for age, sex, race, Atherosclerosis Risk in Communities field center, and multiple baseline risk factors, patients who had a history of MI without diabetes at baseline had 1.9 times the risk of fatal CHD or nonfatal MI (95% CI, 1.35 to 2.56; P<0.001) compared with diabetic patients without a prior history of MI. The nondiabetic patients with MI also had 1.8 times the risk of CVD mortality compared with diabetic patients without MI (95% CI, 1.22 to 2.72; P=0.003). However, stroke risk was similar between diabetic patients without MI and nondiabetic patients with MI (RR, 1.05; 95% CI, 0.61 to 1.79; P=0.87). We also observed that nondiabetic patients with MI had a carotid artery wall thickness similar to diabetic patients without MI (P=0.77).

CONCLUSIONS

Diabetic patients without MI had lower risk of CHD events and mortality from CVD compared with nondiabetic patients with MI, but stroke risk was similar between these 2 groups.

Association of the Lewis genotype with cardiovascular risk factors and subclinical carotid atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) study

OBJECTIVES

To evaluate the relationship of Lewis genotypes with major cardiovascular risk factors and the intima-media thickness (IMT) of carotid arteries. Lewis genotyping included four major mutations of the Lewis (FUT3) gene at nucleotide positions 59, 1067, 202 and 314.

DESIGN

Two complementary population-based cross-sectional studies.

SETTING

The Atherosclerosis Risk in Communities (ARIC) Study.

SUBJECTS

The relationship between Lewis genotype and major cardiovascular risk factors was studied in 761 men and women aged 45-64 years without known clinical atherosclerotic disease; 577 were Caucasians and 184 were African-Americans. The association of Lewis genotype and subclinical carotid atherosclerosis was studied in 419 individuals with, and 819 controls without carotid IMT of >1.0 mm, measured by B-mode ultrasound.

MAIN OUTCOME MEASURES

Mean values of cardiovascular risk factors by Lewis genotype. Lewis genotype frequencies in subclinical carotid atherosclerosis cases and controls.

RESULTS

Individuals with Lewis genotypes consistent with lack of alpha(1,3/1,4)-fucosyltransferase activity (i.e. Lewis-negative genotype) had statistically significantly lower fasting glucose, factor VIIIc, von Willebrand factor and diastolic blood pressure compared with their counterparts with Lewis-positive genotypes. The distribution of Lewis genotypes and haplotypes was not significantly different between individuals with carotid IMT of >1.0 mm (cases) and their controls. The odds of carotid atherosclerosis in carriers of the Lewis-negative genotype was 1.23 (95% confidence interval 0.70-2.16) compared to individuals with Lewis-positive genotype, controlling for age, gender and race/ARIC field centre.

CONCLUSION

The lack of a statistically significant association between Lewis 'genotype' and subclinical atherosclerosis in our data suggests that earlier studies reporting associations at the 'phenotypic' level may reflect aspects of the biology of the Lewis system other than an inherent genetic property.

Prediction of coronary heart disease in middle-aged adults with diabetes

OBJECTIVE

To determine the 10-year probability of coronary heart disease (CHD) in diabetic adults and how well basic and novel risk factors predict CHD risk.

RESEARCH DESIGN AND METHODS

We measured risk factors in 14054 participants (1500 with diabetes) initially free of CHD in the Atherosclerosis Risk in Communities study from 1987 to 1989 and followed them prospectively for CHD incidence through 1998. We used proportional hazards regression models and receiver operating characteristic (ROC) curves for CHD risk prediction.

RESULTS

Based on our model using basic risk factors (age, race, total and HDL cholesterol, systolic blood pressure, antihypertensives, and smoking status), approximately 61% of diabetic women and 86% of diabetic men had a predicted 10-year CHD probability >or=10%. This CHD risk-prediction model had an area under the ROC curve of 0.72 in diabetic women and 0.67 in diabetic men. Novel risk factors or subclinical disease markers individually added only modest predictivity, but the addition of multiple markers (BMI, waist-to-hip ratio, Keys dietary score, serum albumin and creatinine, factor VIII, white blood cell count, left ventricular hypertrophy determined by electrocardiogram, and carotid intima-media thickness) increased the area under the curve by approximately 10%.

CONCLUSIONS

Although all diabetic adults are at high risk for CHD, their variation in CHD risk can be predicted moderately well by basic risk factors. No single novel risk marker greatly enhanced absolute CHD risk assessment, but a battery of novel markers did. Our model can provide estimates of CHD risk for the primary prevention of this disease in people with type 2 diabetes.

Coronary heart disease risk prediction in the Atherosclerosis Risk in Communities (ARIC) study

Risk prediction functions for incident coronary heart disease (CHD) were estimated using data from the Atherosclerosis Risk in Communities (ARIC) Study, a prospective study of CHD in 15,792 persons recruited in 1987-1989 from four U.S. communities, with follow-up through 1998. Predictivity of which individuals had incident CHD was assessed by increase in area under ROC curves resulting from adding nontraditional risk factors and markers of subclinical disease to a basic model containing only traditional risk factors. We also assessed the increase in population attributable risk. The additional factors were body mass index; waist-hip ratio; sport activity index; forced expiratory volume; plasma fibrinogen, factor VIII, von Willebrand factor, and Lp(a); heart rate; Keys score; pack-years smoking; and subclinical disease marker carotid intima-media thickness. These factors substantially improved prediction of future CHD for men, less for women, and also increased attributable risks.

Impact of multiple coronary risk factors on the intima-media thickness of different segments of carotid artery in healthy young adults (The Bogalusa Heart Study)

Although risk factors for coronary artery disease are also associated with increased carotid artery intima-media thickness (IMT) as measured by B-mode ultrasonography in middle-aged and older persons, information on the impact of multiple risk factors on the IMT of different segments of the carotid artery in young adults is limited. This relation was examined in a sample of 518 black and white subjects (mean age 32 years; 71% white, 39% male) enrolled in the Bogalusa Heart Study. IMT was thicker and more skewed in the bulb compared with other carotid segments. Race differences (blacks more than whites) were noted for the common carotid (p <0.001) and carotid bulb (bifurcation) IMT (women only, p <0.001). Men had a greater IMT in the common carotid (p <0.05), internal carotid (p <0.05), and carotid bulb (whites only, p <0.001). In a multivariate analysis, systolic blood pressure, race, age, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol weree entered into a model in that order and accounted for the 16.7% variance in the common carotid IMT; age, systolic blood pressure, HDL cholesterol, LDL cholesterol, race, and insulin levels explained the 19.4% variance in the carotid bulb IMT. Gender and body mass index (BMI) accounted for the 4.7% variance in the internal carotid IMT. Increases in IMT with increasing number of risk factors (cigarette smoking, higher total cholesterol to HDL cholesterol ratio, higher systolic blood pressure, greater waist circumference, and higher insulin level) were noted for the common carotid and carotid bulb segments (p for trend <0.001 for both). The observed deleterious trend of increasing IMT at different carotid segments with increasing number of risk factors in free-living, asymptomatic young subjects underscores the importance of profiling multiple risk factors early in life. Ultrasonography of carotid arteries, especially at the bifurcation, may be helpful along with measurements of risk factors for evaluation of asymptomatic atherosclerotic disease.

Automated analysis of brachial ultrasound image sequences: early detection of cardiovascular disease via surrogates of endothelial function

Early detection of cardiovascular disease would allow timely institution of preventive measures. Arterial endothelium play a primary role in processes leading to the development of atherosclerotic plaque and cardiovascular disease in general. Determination of flow-mediated dilatation (FMD) of brachial arteries from B-mode ultrasound image sequences offers a noninvasive surrogate index of endothelial function. A highly automated method for analysis of brachial ultrasound image sequences is reported and its performance assessed. The method overcomes the variability of brachial ultrasound images across subjects by incorporating machine learning and quality control steps. The automated method outperformed conventional manual analysis by providing a decreased analysis bias, increased reproducibility, and improved measurement accuracy. Consequently, it decreases inter- and intraobserver as well interinstitution variability. The method has been employed in a number of population studies with thousands of subjects analyzed.

Impact of body mass index on changes in common carotid artery wall thickness

OBJECTIVE

To examine associations between changes in body mass index (BMI) and changes in carotid artery intima-media thickness (IMT) in a community-based sample.

RESEARCH METHODS AND PROCEDURES

Carotid artery IMT and BMI were assessed at baseline (between 1987 and 1990) and in three subsequent examinations at 3-year intervals in participants in the Atherosclerosis Risk in Communities cohort. The 9,316 African-American and white men and women in the analysis were 45 to 64 years of age at baseline. Cross-sectional associations between BMI and IMT were assessed using general linear models. Longitudinal associations were examined using mixed models analysis.

RESULTS

Cross-sectional associations between BMI and IMT were confirmed. At baseline, a 1-kg/m(2) increase in BMI was associated with an increase in IMT that ranged from 2.5 to 7.5 micro m among the ethnic-gender groups examined. Changes in BMI were not associated with changes in IMT in models that adjusted for aging and other covariates. Results were similar across ethnic-gender groups.

DISCUSSION

Among free-living, 45- to 64-year-old adults, changes in common carotid artery IMT associated with changes in BMI are either very small or absent.

The association of atherosclerosis, vascular risk factors, and retinopathy in adults with diabetes : the atherosclerosis risk in communities study

PURPOSE

The aim of this report is to describe the prevalence of retinopathy and its associations with atherosclerosis and vascular risk factors in people with diabetes.

DESIGN

Cross-sectional study.

PARTICIPANTS

Persons with diabetes, having gradable fundus photographs, from a biracial population-based cohort of adults (ages 51-72 years), and living in four United States communities (Forsyth County, North Carolina; the city of Jackson, Mississippi; suburbs of Minneapolis, Minnesota; and Washington County, Maryland) were studied from 1993 to 1995.

METHODS

Lesions typical of diabetic retinopathy were detected by grading a 45 degrees color fundus photograph of one eye of each participant, using a modification of the Airlie House classification system.

MAIN OUTCOME MEASURE

Severity of diabetic retinopathy (none, minimal nonproliferative, moderate nonproliferative, severe nonproliferative, and proliferative) and macular edema.

RESULTS

Retinopathy was detected in 328/1600 (20.5%) of those with diabetes; 114/1724 (6.6%) had hard exudate, 28/1600 (1.8%) had proliferative diabetic retinopathy, and 27/1662 (1.6%) had macular edema. The prevalence of diabetic retinopathy was higher in blacks (27.7%) compared with whites (16.7%). Controlling for duration of diabetes, serum glucose, systolic blood pressure, and type of diabetes medications taken, severity of retinopathy was associated with carotid artery intima-media wall thickness (odds ratio [OR]/0.1-mm thickness 1.09; 95% confidence interval [CI], 1.01, 1.17; P = 0.01), serum albumin (OR/0.1 g/dl 0.94; 95% CI, 0.88, 0.99; P = 0.02), but not race (OR blacks versus whites,1.24; 95% CI, 0.88, 1.75; P = 0.21). Severity of diabetic retinopathy was not associated with coronary artery disease or stroke history or any of the plasma lipids studied. Controlling for age, gender, duration of diabetes, serum glucose, and type of diabetes medications taken, the presence of retinal hard exudates was associated with plasma low-density lipoprotein cholesterol (OR/10 mg/dl 1.18; 95% CI, 1.09, 1.29; P < 0.001), and plasma Lp(a) (OR/10 mg/dl 1.02; 95% CI, 1.00, 1.05; P = 0.04) but not race or blood pressure.

CONCLUSIONS

These data suggest that plasma lipids are associated with the presence of hard exudate and that carotid artery intima-media wall thickness is associated with retinopathy, but other manifestations of atherosclerosis and most of its risk factors are not associated with severity of diabetic retinopathy.

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

In a cross-sectional study of 8695 men and women free of clinical CVD, aged 45-64 years at the 1987-1989 baseline Atherosclerosis Risk in Communities (ARIC) study exam, we examined the relationship between carotid artery lesions (CALs), with and without acoustic shadowing (AS) as an index of plaque mineralization, to systemic markers of inflammation and markers of endothelial function, including endothelial adhesion molecules. A three-level variable, based on the presence of extracranial CALs and AS, identified by B-mode ultrasound of six 1 cm arterial segments, defined the outcome. Among subjects without evidence of AS, after controlling for age, gender, ethnicity, study site, body mass index, hypertension, diabetes, and smoking status, CALs were associated with systemic markers of inflammation, including higher levels of fibrinogen [OR=1.24 (95% CI: 1.09, 1.40)] and white blood cell count [OR=1.37 (95% CI: 1.21, 1.56)]. Among subjects with a CAL, after controlling for the above risk factors as well as mean far wall intima-media thickness, AS was associated with higher levels of von Willebrand factor [OR=1.38 (95% CI: 1.10, 1.74)], a marker of endothelial activation. Associations with endothelial adhesion molecules were inconsistent. Further studies aimed at elucidating the mechanisms of arterial mineralization are warranted.