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1.  Associations of common carotid intima-media thickness (IMT) with coronary heart disease risk factors and events vary with distance from the carotid bulb 
Background
Common carotid artery (CCA) intima-media thickness (IMT) can be measured by ultrasound near to or below the carotid bulb. This might affect associations of IMT with coronary heart disease (CHD) risk factors and events.
Methods
We performed IMT measurements near and below the divergence of the CCA bulb, in 279 white individuals, aged 45–54 years, free of CHD at baseline and a subset of the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort composed of Whites, Blacks, Chinese and Hispanics. Participants were followed for an average of 8.2 years. Far wall mean of the maximum IMT (MMaxIMT) and mean of the mean IMT (MMeanIMT) of the right and left CCA were averaged. Framingham risk factors were used in multivariable linear regression models. Parsimonious Cox proportional regression models included first time CHD as outcome.
Results
MMeanIMT below the bulb was smaller than near the bulb (0.51 mm +/− 0.078 mm versus 0.56 +/− 0.088 mm; p < 0.001) and had similar associations with risk factors (model R2 of 0.215 versus 0.186). MMaxIMT below the bulb was associated with risk factors (model R2: 0.211), MMaxIMT near to the bulb was not (R2: 0.025). MMeanIMT and MMaxIMT below the bulb were associated with CHD events (HR 1.67; p = 0.047 and 1.72; p= 0.037, respectively) but not when measured near the bulb.
Conclusions
CCA IMT measurements made below the bulb are smaller but have more consistent associations with CHD risk factors and outcomes as compared to IMT measured near the bulb.
doi:10.1016/j.echo.2014.04.019
PMCID: PMC4149919  PMID: 24944141
risk factors; common carotid artery; ultrasound; coronary heart disease; intima media thickness; carotid artery bifurcation
2.  Plasma and serum L-selectin and clinical and subclinical the Multi-Ethnic Study of Atherosclerosis (MESA)cardiovascular disease 
L-selectin has been suggested to play a role in atherosclerosis. Previous studies on cardiovascular disease (CVD) and serum or plasma L-selectin are inconsistent. The association of serum L-selectin (sL-selectin) with carotid intima-media thickness, coronary artery calcium, ankle-brachial index (subclinical CVD) and incident CVD was assessed within 2403 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Regression analysis and the Tobit model were used to study subclinical disease; Cox Proportional Hazards regression for incident CVD. Mean age was 63 ± 10, 47% were males; mean sL-selectin was significantly different across ethnicities. Within each race/ethnicity, sL-selectin was associated with age and sex; among Caucasians and African Americans, it was associated with smoking status and current alcohol use. sL-selectin levels did not predict subclinical or clinical CVD after correction for multiple comparisons. Conditional logistic regression models were used to study plasma L-selectin and CVD within 154 incident CVD cases, occurred in a median follow up of 8.5 years, and 306 age-, sex-, and ethnicity-matched controls. L-selectin levels in plasma were significantly lower than in serum and the overall concordance was low. Plasma levels were not associated with CVD. In conclusion, this large multi-ethnic population, soluble L-selectin levels did not predict clinical or subclinical CVD.
doi:10.1016/j.trsl.2014.02.001
PMCID: PMC4029851  PMID: 24631064
atherosclerosis; cardiovascular diseases; ethnic groups; L-selectin
3.  Edge-Detected Common Carotid Artery Intima–Media Thickness and Incident Coronary Heart Disease in the Multi-Ethnic Study of Atherosclerosis 
Background
Common carotid artery intima–media thickness (IMT) can be measured either by hand or with an automated edge detector. We performed a direct comparison of these 2 approaches and studied their respective associations with coronary heart disease outcomes.
Methods and Results
We studied 5468 participants of the Multi-Ethnic Study of Atherosclerosis, composed of white, Chinese, Hispanic, and black participants with an average age of 61.9 years (47.8% men) and who were free of coronary heart disease at baseline. Manual-traced and edge-detected IMT measurements were made in the same location on ultrasound images of the right common carotid artery far wall in an area free of plaque. Manual-traced and edge-detected common carotid artery IMT measurements were added separately to multivariable Cox proportional hazards models with time to incident coronary heart disease as the outcome and adjusted for traditional coronary heart disease Framingham risk factors, lipid-lowering therapy, blood pressure–lowering therapy, and race or ethnicity. Additional models were generated after adding clinic site and reader. There were 349 events during a median follow-up of 10.2 years. In adjusted models, the hazard ratio was not significant (1.31; 95% CI 0.84 to 2.06) for each millimeter increase in manual-traced IMT but was significant for edge-detected IMT (hazard ratio 1.63; 95% CI 1.12 to 2.37). Edge-detected IMT remained statistically associated with outcomes after additional adjustment for clinic site and reader performing the IMT measurement (hazard ratio 1.59; 95% CI 1.07 to 2.35).
Conclusions
Edge-detected common carotid artery far wall IMT has similar if not stronger associations with coronary heart disease outcomes when compared with manual-traced IMT.
Clinical Trial Registration
URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00063440.
doi:10.1161/JAHA.114.001492
PMCID: PMC4599522  PMID: 26077584
atherosclerosis; carotid arteries; epidemiology; risk factors; ultrasonics
4.  Association of Subclinical Atherosclerosis Using Carotid Intima-Media Thickness, Carotid Plaque, and Coronary Calcium Score with Left Ventricular Dyssynchrony: The Multi-Ethnic Study of Atherosclerosis 
Atherosclerosis  2015;239(2):412-418.
Background
The role of atherosclerosis in the progression of global left ventricular dysfunction and cardiovascular events has been well recognized. Left ventricular (LV) dyssynchrony is a measure of regional myocardial dysfunction. Our objective was to investigate the relationship of subclinical atherosclerosis with mechanical LV dyssynchrony in a population-based asymptomatic multi-ethnic cohort.
Methods and Results
Participants of the Multi-Ethnic Study of Atherosclerosis (MESA) at exam 5 were evaluated using 1.5T cardiac magnetic resonance (CMR) imaging, carotid ultrasound (n=2,062) for common carotid artery (CCA) and internal carotid artery (ICA) intima-media thickness (IMT), and cardiac computed tomography (n=2,039) for coronary artery calcium (CAC) assessment (Agatston method). Dyssynchrony indices were defined as the standard deviation of time to peak systolic circumferential strain (SD-TPS) and the difference between maximum and minimum (max-min) time to peak strain using harmonic phase imaging in 12 segments (3-slices × 4 segments). Multivariable regression analyses were performed to assess associations after adjusting for participant demographics, cardiovascular risk factors, LV mass, and ejection fraction. In multivariable analyses, SD-TPS was significantly related to measures of atherosclerosis, including CCA-IMT (8.7msec/mm change in IMT, p=0.020), ICA-IMT (19.2 msec/mm change in IMT, p<0.001), carotid plaque score (1.2 msec/unit change in score, p<0.001), and log transformed CAC+1 (0.66 msec/unit log-CAC+1, p=0.018). These findings were consistent with other parameter of LV dyssynchrony i.e. max-min.
Conclusion
In the MESA cohort, measures of atherosclerosis are associated with parameters of subclinical LV dyssynchrony in the absence of clinical coronary event and left-bundle-branch block.
doi:10.1016/j.atherosclerosis.2015.01.041
PMCID: PMC4361257  PMID: 25682041
Left Ventricular Dyssynchrony; Carotid IMT; Coronary Calcium Score; Atherosclerosis
5.  The Relationship of Cigarette Smoking with Inflammation and Subclinical Vascular Disease: The Multi-Ethnic Study of Atherosclerosis 
Objectives
We sought to assess the impact of smoking status, cumulative pack-years, and time since cessation (the latter in former-smokers only) on three important domains of cardiovascular disease (CVD): inflammation, vascular dynamics and function, and subclinical atherosclerosis.
Approach and Results
The MESA cohort enrolled 6,814 adults without prior CVD. Smoking variables were determined by self-report and confirmed with urinary cotinine. We examined cross-sectional associations between smoking parameters and; 1) inflammatory biomarkers (high-sensitivity C-reactive protein [hsCRP], interleukin-6 [IL-6], and fibrinogen); 2) vascular dynamics and function (brachial flow-mediated dilation [FMD] and carotid distensibility by ultrasound, as well as aortic distensibility by MRI); and 3) subclinical atherosclerosis (coronary artery calcification [CAC], carotid intima-media thickness [CIMT], and ankle-brachial index [ABI]). We identified 3,218 never-smokers, 2,607 former-smokers, and 971 current-smokers. Mean age was 62 years and 47% were male. There was no consistent association between smoking and vascular distensibility or FMD outcomes. In contrast, compared to never-smokers, the adjusted association between current-smoking and measures of either inflammation or subclinical atherosclerosis was consistently stronger than for former-smoking (e.g. odds-ratio (OR) for hs-CRP > 2mg/L of 1.7 [95%CI, 1.5-2.1] Vs. 1.2 [1.1-1.4], OR for CAC > 0 of 1.8 [1.5-2.1] Vs. 1.4 [1.2-1.6], respectively). Similar associations were seen for IL-6, fibrinogen, CIMT, and ABI. A monotonic relationship was also found between increasing pack-years exposure and elevated inflammatory markers. Further, current smokers with hsCRP > 2mg/L were more likely to have increased CIMT, abnormal ABI, and CAC > 75th percentile for age, sex and race (relative to smokers with hsCRP < 2mg/L, interaction p < 0.05 for all three outcomes). In contrast, time since quitting in former-smokers was independently associated with lower inflammation and atherosclerosis (e.g. OR for hsCRP > 2mg/L of 0.91 [0.88-0.95] and OR for CAC > 0 of 0.94 [0.90-0.97] for every 5-year cessation interval).
Conclusion
These findings expand our understanding of the harmful effects of smoking and help explain the cardiovascular benefits of smoking cessation.
doi:10.1161/ATVBAHA.114.304960
PMCID: PMC4484586  PMID: 25745060
Smoking; Inflammation; Atherosclerosis; Coronary Artery Calcium
6.  Incident stroke is associated with common carotid artery diameter and not common carotid artery intima-media thickness 
Background and Purpose
The common carotid artery (CCA) inter-adventitial diameter (IAD) is measured on ultrasound images as the distance between the media-adventitia interfaces of the near and far walls. It is associated with common carotid intima-media thickness (IMT) and left ventricular mass and might therefore also have an association with incident stroke.
Methods
We studied 6255 individuals free of coronary heart disease and stroke at baseline with mean age of 62.2 years (47.3% men), members of a multi-ethnic community based cohort of whites, blacks, Hispanics, and Chinese. Ischemic stroke events were centrally adjudicated. CCA IAD and IMT were measured. Cases with incident atrial fibrillation (n = 385) were excluded. Multivariable Cox proportional hazards models were generated with time to ischemic event as outcome, adjusting for risk factors.
Results
There were 115 first time ischemic strokes at 7.8 years of follow-up. CCA IAD was a significant predictor of ischemic stroke (Hazard ratio: 1.86; 95%CI 1.59, 2.17 per mm) and remained so after adjustment for risk factors and common carotid IMT with a hazard ratio of 1.52 per mm (95% CI: 1.22, 1.88). Common carotid IMT was not an independent predictor after adjustment (hazard ratio 0.14; 95% CI: 0.14, 1.19).
Conclusion
While common carotid IMT is not associated with stroke, inter-adventitial diameter of the common carotid artery is independently associated with first time incident ischemic stroke even after adjusting for IMT. Our hypothesis that this is in part due to the effects of exposure to blood pressure needs confirmation by other studies.
doi:10.1161/STROKEAHA.114.004850
PMCID: PMC4270293  PMID: 24643408
7.  Detailed analysis of association between common single nucleotide polymorphisms and subclinical atherosclerosis: The Multi-ethnic Study of Atherosclerosis 
Data in Brief  2016;7:229-242.
Previously identified single nucleotide polymorphisms (SNPs) in genome wide association studies (GWAS) of cardiovascular disease (CVD) in participants of mostly European descent were tested for association with subclinical cardiovascular disease (sCVD), coronary artery calcium score (CAC) and carotid intima media thickness (CIMT) in the Multi-Ethnic Study of Atherosclerosis (MESA). The data in this data in brief article correspond to the article Common Genetic Variants and Subclinical Atherosclerosis: The Multi-Ethnic Study of Atherosclerosis [1]. This article includes the demographic information of the participants analyzed in the article as well as graphical displays and data tables of the association of the selected SNPs with CAC and of the meta-analysis across ethnicities of the association of CIMT-c (common carotid), CIMT-I (internal carotid), CAC-d (CAC as dichotomous variable with CAC>0) and CAC-c (CAC as continuous variable, the log of the raw CAC score plus one) and CVD. The data tables corresponding to the 9p21 fine mapping experiment as well as the power calculations referenced in the article are also included.
doi:10.1016/j.dib.2016.01.048
PMCID: PMC4773483  PMID: 26958643
Single nucleotide polymorphism (SNP); Common genetic variant; Subclincal atherosclerosis; Coronary artery calcium (CAC); Carotid intima-media thickness (CIMT)
8.  Inflammatory markers and extent and progression of early atherosclerosis: Meta-analysis of individual-participant-data from 20 prospective studies of the PROG-IMT collaboration 
Background
Large-scale epidemiological evidence on the role of inflammation in early atherosclerosis, assessed by carotid ultrasound, is lacking. We aimed to quantify cross-sectional and longitudinal associations of inflammatory markers with common-carotid-artery intima-media thickness (CCA-IMT) in the general population.
Methods
Information on high-sensitivity C-reactive protein, fibrinogen, leucocyte count and CCA-IMT was available in 20 prospective cohort studies of the PROG-IMT collaboration involving 49,097 participants free of pre-existing cardiovascular disease. Estimates of associations were calculated within each study and then combined using random-effects meta-analyses.
Results
Mean baseline CCA-IMT amounted to 0.74mm (SD = 0.18) and mean CCA-IMT progression over a mean of 3.9 years to 0.011 mm/year (SD = 0.039). Cross-sectional analyses showed positive linear associations between inflammatory markers and baseline CCA-IMT. After adjustment for traditional cardiovascular risk factors, mean differences in baseline CCA-IMT per one-SD higher inflammatory marker were: 0.0082mm for high-sensitivity C-reactive protein (p < 0.001); 0.0072mm for fibrinogen (p < 0.001); and 0.0025mm for leucocyte count (p = 0.033). ‘Inflammatory load’, defined as the number of elevated inflammatory markers (i.e. in upper two quintiles), showed a positive linear association with baseline CCA-IMT (p < 0.001). Longitudinal associations of baseline inflammatory markers and changes therein with CCA-IMT progression were null or at most weak. Participants with the highest ‘inflammatory load’ had a greater CCA-IMT progression (p = 0.015).
Conclusion
Inflammation was independently associated with CCA-IMT cross-sectionally. The lack of clear associations with CCA-IMT progression may be explained by imprecision in its assessment within a limited time period. Our findings for ‘inflammatory load’ suggest important combined effects of the three inflammatory markers on early atherosclerosis.
doi:10.1177/2047487314560664
PMCID: PMC4544641  PMID: 25416041
Inflammation; atherosclerosis; meta-analysis
9.  Carotid artery plaque and progression of coronary artery calcium: the Multi-Ethnic Study of Atherosclerosis 
Background
Carotid and coronary atherosclerosis are associated to each other in imaging and autopsy studies. We evaluated whether carotid artery plaque seen on carotid ultrasound can predict incident coronary artery calcification (CAC).
Materials and Methods
We repeated Agatston calcium score measurements in 5445 participants of the Multi-Ethnic Study of Atherosclerosis (MESA) (mean age 57.9 years; 62.9% female). Internal carotid artery lesions were graded as 0%, 1-24%, >25% diameter narrowing and intima-media thickness (IMT) was measured. Plaque was present for any stenosis > 0%. CAC progression was evaluated with multivariable relative risk regression in cases with CAC = 0 at baseline and with multivariable linear regression for CAC > 0 adjusting for cardiovascular risk factors, body mass index, ethnicity, and common carotid IMT.
Results
CAC was positive at baseline in 2708/5445 (49.7%) participants and became positive in 458/2837 (16.1%) at mean interval of 2.4 years between repeat examinations. Plaque and ICA IMT were both strongly associated with presence of CAC. After statistical adjustment, presence of carotid artery plaque significantly predicted incident CAC with a relative risk(RR) of 1.37 (95% Confidence Intervals: 1.12, 1.67). Incident CAC was associated with ICA IMT with an RR of 1.13 (95% Confidence Intervals: 1.03, 1.25) for each mm increase. Progression of CAC was also significantly associated (p < 0.001) with plaque and ICA IMT.
Conclusions
In individuals free of cardiovascular disease, subjective and quantitative measures of carotid artery plaques by ultrasound imaging are associated with CAC incidence and progression.
doi:10.1016/j.echo.2013.02.009
PMCID: PMC4084492  PMID: 23522805
10.  Association of exhaled carbon monoxide with subclinical cardiovascular disease and their conjoint impact on the incidence of cardiovascular outcomes 
European Heart Journal  2014;35(42):2980-2987.
Aims
Whereas endogenous carbon monoxide (CO) is cytoprotective at physiologic levels, excess CO concentrations are associated with cardiometabolic risk and may represent an important marker of progression from subclinical to clinical cardiovascular disease (CVD).
Methods and results
In 1926 participants of the Framingham Offspring Study (aged 57 ± 10 years, 46% women), we investigated the relationship of exhaled CO, a surrogate of blood CO concentration, with both prevalent subclinical CVD and incident clinical CVD events. Presence of subclinical CVD was determined using a comprehensive panel of diagnostic tests used to assess cardiac and vascular structure and function. Individuals with the highest (>5 p.p.m.) compared with lowest (≤4 p.p.m.) CO exposure were more likely to have subclinical CVD [odds ratios (OR): 1.67, 95% CI: 1.32–2.12; P < 0.001]. During the follow-up period (mean 5 ± 3 years), 193 individuals developed overt CVD. Individuals with both high CO levels and any baseline subclinical CVD developed overt CVD at an almost four-fold higher rate compared with those with low CO levels and no subclinical disease (22.1 vs. 6.3%). Notably, elevated CO was associated with incident CVD in the presence [hazards ration (HR): 1.83, 95% CI: 1.08–3.11; P = 0.026] but not in the absence (HR: 0.80, 95% CI: 0.42–1.53; P = 0.51) of subclinical CVD (Pinteraction = 0.019). Similarly, subclinical CVD was associated with incident CVD in the presence of high but not low CO exposure.
Conclusion
Our findings in a community-based sample suggest that elevated CO is a marker of greater subclinical CVD burden and, furthermore, a potential key component in the progression from subclinical to clinical CVD.
doi:10.1093/eurheartj/ehu052
PMCID: PMC4271053  PMID: 24574370
Carbon monoxide; Subclinical vascular disease; Cardiovascular outcomes
11.  Healthy Lifestyle Change and Subclinical Atherosclerosis in Young Adults: Coronary Artery Risk Development in Young Adults (CARDIA) Study 
Circulation  2014;130(1):10-17.
Background
The benefits of healthy habits are well-established, but it is unclear whether making health behavior changes as an adult can still alter coronary artery disease risk.
Methods and Results
The Coronary Artery Risk Development in Young Adults (CARDIA) prospective cohort study (n = 3538) assessed 5 healthy lifestyle factors (HLFs) among young adults between ages 18–30 (Year 0 baseline) and 20 years later (Year 20): not overweight/obese, low alcohol intake, healthy diet, physically active, nonsmoker. We tested whether change from Year 0 to 20 in a continuous composite HLF score (HLF change; range: −5 to +5) is associated with subclinical atherosclerosis [coronary artery calcification (CAC) and carotid intima-media thickness (IMT)] at Year 20, after adjustment for demographics, medications, and baseline HLFs. By Year 20, 25·3% of the sample improved (HLF change ≥ +1); 40·4% deteriorated (had fewer HLFs); 34·4% stayed the same; 19·2% had CAC (>0). Each increase in HLFs was associated with reduced odds of detectable CAC (OR = .85, 95% CI: .74 – .98) and lower IMT (carotid bulb β = −.024, p = 0.001), and each decrease in HLFs was predictive to a similar degree of greater odds of CAC (OR = 1.17, 95% CI: 1.02 – 1.33) and greater IMT (β = +.020, p < 0.01).
Conclusions
Healthy lifestyle changes during young adulthood are associated with decreased, and unhealthy lifestyle changes with increased risk for subclinical atherosclerosis in middle age.
doi:10.1161/CIRCULATIONAHA.113.005445
PMCID: PMC4615574  PMID: 24982115
epidemiology; follow-up studies; risk factors; prevention; behavior modification
12.  Individual-Level Concentrations of Fine Particulate Matter Chemical Components and Subclinical Atherosclerosis: A Cross-Sectional Analysis Based on 2 Advanced Exposure Prediction Models in the Multi-Ethnic Study of Atherosclerosis 
American Journal of Epidemiology  2014;180(7):718-728.
Long-term exposure to outdoor particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM2.5) has been associated with cardiovascular morbidity and mortality. The chemical composition of PM2.5 that may be most responsible for producing these associations has not been identified. We assessed cross-sectional associations between long-term concentrations of PM2.5 and 4 of its chemical components (sulfur, silicon, elemental carbon, and organic carbon (OC)) and subclinical atherosclerosis, measured as carotid intima-media thickness (CIMT) and coronary artery calcium, between 2000 and 2002 among 5,488 Multi-Ethnic Study of Atherosclerosis participants residing in 6 US metropolitan areas. Long-term concentrations of PM2.5 components at participants' homes were predicted using both city-specific spatiotemporal models and a national spatial model. The estimated differences in CIMT associated with interquartile-range increases in sulfur, silicon, and OC predictions from the spatiotemporal model were 0.022 mm (95% confidence interval (CI): 0.014, 0.031), 0.006 mm (95% CI: 0.000, 0.012), and 0.026 mm (95% CI: 0.019, 0.034), respectively. Findings were generally similar using the national spatial model predictions but were often sensitive to adjustment for city. We did not find strong evidence of associations with coronary artery calcium. Long-term concentrations of sulfur and OC, and possibly silicon, were associated with CIMT using 2 distinct exposure prediction modeling approaches.
doi:10.1093/aje/kwu186
PMCID: PMC4172166  PMID: 25164422
atherosclerosis; cardiovascular diseases; carotid intima-media thickness; cohort studies; particulate matter
13.  Variations in Common Carotid Artery Intima-Media Thickness (cIMT) during the Cardiac Cycle: Implications for Cardiovascular Risk Assessment 
Introduction
Common carotid artery (CCA) intima-media thickness (cIMT), a measure of atherosclerosis, varies between peak-systole (PS) and end-diastole (ED). This difference might affect cardiovascular risk assessment.
Materials and methods
IMT measurements of the right and left CCA were synchronized with an electrocardiogram: R-wave for ED and T-wave for PS. IMT was measured in 2930 members of the Framingham Offspring Study. Multivariable regression models were generated with ED-IMT, PS-IMT and change in IMT as dependent variables and Framingham risk factors as independent variables. ED-IMT estimates were compared to the upper quartile of IMT based on normative data obtained at PS.
Results
The average age of our population was 57.9 years. Average difference in IMT during the cardiac cycle was 0.037 mm (95% CI: 0.035–0.038 mm). ED-IMT and PS-IMT had similar associations with Framingham risk factors (total R2= 0.292 versus 0.275) and were significantly associated with all risk factors. In a fully adjusted multivariable model, a thinner IMT at peak-systole was associated with pulse pressure (p < 0.0001), LDL-cholesterol (p = 0.0064), age (p = 0.046), and no other risk factors. Performing ED-IMT measurements while using upper quartile PS-IMT normative data lead to inappropriately increasing by 42.1% the number of individuals in the fourth IMT quartile (high cardiovascular risk category).
Conclusion
The difference in IMT between peak-systole and end-diastole is associated with pulse pressure, LDL-cholesterol, and age. In our study, mean IMT difference during the cardiac cycle lead to an overestimation by 42.1% of individuals at high risk for cardiovascular disease.
doi:10.1016/j.echo.2012.05.007
PMCID: PMC3544292  PMID: 22721828
Ultrasonics; Risk Factors; Carotid Arteries; Blood Pressure; systole; diastole
14.  What Do Carotid Intima-Media Thickness and Plaque Add to Prediction of Stroke and Cardiovascular Disease Risk in Older Adults? The Cardiovascular Health Study 
Background
We evaluated whether addition of carotid ultrasound intima-media thickness (CIMT) measurements and risk categories of plaque help predict incident stroke and CVD in older adults.
Methods
Carotid ultrasound studies were recorded in the multicenter Cardiovascular Health Study (CHS). Cardiovascular disease (CVD) was defined as coronary heart disease plus heart failure plus stroke. Ten-year risk prediction Cox proportional hazards models for stroke and CVD were calculated using CHS-specific coefficients for Framingham Risk Score (FRS) factors. Categories of CIMT and CIMT plus plaque were added to FRS prediction models and categorical net reclassification improvement (NRI) and Harrell’s c-statistic were calculated.
Results
In 4,384 CHS participants (61% women, 14% black, baseline age 72 ± 5 yrs) without CVD at baseline, higher CIMT category and presence of plaque were both associated with higher incidence rates for stroke and CVD. Addition of CIMT improved ability of FRS-type risk models to discriminate cases from non-cases of incident stroke and CVD (NRI = 0.062, p=0.015 and NRI=0.027, p<0.001 respectively), with no further improvement by adding plaque. For both outcomes, NRI was driven by down-classifying those without incident disease. Although addition of plaque to CIMT did not result in a significant NRI for either outcome, it was significant among those without incident disease.
Conclusion
In older adults, addition of CIMT modestly improves 10-year risk prediction for stroke and CVD beyond a traditional risk factor model, mainly by down-classifying risk in those without stroke or CVD; addition of plaque to CIMT adds no statistical benefit in the overall cohort, although there is evidence of down-classification in those without events.
doi:10.1016/j.echo.2014.06.013
PMCID: PMC4158921  PMID: 25172401
15.  Common Carotid Intima-Media Thickness Measurements Do Not Improve Cardiovascular Risk Prediction in Individuals With Elevated Blood Pressure 
Hypertension  2014;63(6):1173-1181.
Carotid intima-media thickness (CIMT) is a marker of cardiovascular risk. It is unclear whether measurement of mean common CIMT improves 10-year risk prediction of first-time myocardial infarction or stroke in individuals with elevated blood pressure. We performed an analysis among individuals with elevated blood pressure (ie, a systolic blood pressure ≥140 mm Hg and a diastolic blood pressure ≥ 90 mm Hg) in USE-IMT, a large ongoing individual participant data meta-analysis. We refitted the risk factors of the Framingham Risk Score on asymptomatic individuals (baseline model) and expanded this model with mean common CIMT (CIMT model) measurements. From both models, 10-year risks to develop a myocardial infarction or stroke were estimated. In individuals with elevated blood pressure, we compared discrimination and calibration of the 2 models and calculated the net reclassification improvement (NRI). We included 17 254 individuals with elevated blood pressure from 16 studies. During a median follow-up of 9.9 years, 2014 first-time myocardial infarctions or strokes occurred. The C-statistics of the baseline and CIMT models were similar (0.73). NRI with the addition of mean common CIMT was small and not significant (1.4%; 95% confidence intervals, −1.1 to 3.7). In those at intermediate risk (n=5008, 10-year absolute risk of 10% to 20%), the NRI was 5.6% (95% confidence intervals, 1.6–10.4). There is no added value of measurement of mean common CIMT in individuals with elevated blood pressure for improving cardiovascular risk prediction. For those at intermediate risk, the addition of mean common CIMT to an existing cardiovascular risk score is small but statistically significant.
doi:10.1161/HYPERTENSIONAHA.113.02683
PMCID: PMC4523133  PMID: 24614213
atherosclerosis; carotid intima-media thickness; primary prevention; prognosis; risk
16.  Mediation of Cardiovascular Risk Factor Effects Through Subclinical Vascular Disease: The Multi-Ethnic Study of Atherosclerosis 
Objective
It is unclear to what extent subclinical cardiovascular disease (CVD) such as coronary artery calcium (CAC), carotid intima-media thickness (CIMT) and brachial flow mediated dilation (FMD) are mediators of the known associations between traditional cardiovascular risk factors and incident CVD events. We assessed the portion of the effects of risk factors on incident CVD events that are mediated through CAC, CIMT and FMD.
Approach and Results
6355 out of 6814 MESA participants were included. Nonlinear implementation of structural equation modeling (STATA mediation package) were used to assess whether CAC, CIMT or FMD are mediators of the association between traditional risk factors and incident CVD event.
Mean age of 62, with 47% males, 12% diabetics and 13% current smokers. Mean follow up of 7.5 years, 539 CVD events were adjudicated. CAC showed the highest mediation while FMD showed the least. Age had the highest percent of total effect mediated via CAC for CVD outcomes while current cigarette smoking had the least percent of total effect mediated via CAC [percent (95%CI: 80.2(58.8, 126.7) % vs. 10.6(6.1, 38.5) % respectively). BMI showed the highest percent of total effect mediated via CIMT [17.7(11.6, 38.9) %], only a negligible amount of the association between traditional risk factors and CVD was mediated via FMD.
Conclusion
Many of the risk factors for incident CVD (other than age, sex and BMI) showed a modest level of mediation via CAC, CIMT and FMD suggesting that current subclinical CVD markers may not be optimal intermediaries for gauging upstream risk factor modification
doi:10.1161/ATVBAHA.114.303753
PMCID: PMC4329880  PMID: 24876350
17.  Association of Parity with Carotid Diameter and Distensibility: Multi-Ethnic Study of Atherosclerosis 
Hypertension  2014;64(2):253-258.
Pregnancy and childbirth are associated with hemodynamic changes and vascular remodeling. It is not known whether parity is associated with later adverse vascular properties such as larger arterial diameter, wall thickness and lower distensibility.
We used baseline data from 3283 women free of cardiovascular disease aged 45-84 years enrolled in the population based Multi-Ethnic Study of Atherosclerosis. Participants self-reported parity status. Ultrasound derived carotid artery lumen diameters and brachial artery blood pressures were measured at peak-systole and end-diastole. Common carotid intima media thickness (cIMT) was also measured. Regression models to determine the association of carotid distensibility coefficient, lumen diameter, and cIMT with parity were adjusted for age, race, height, weight, diabetes, current smoking, BP medication use, total and high density lipoprotein cholesterol levels.
The prevalence of nulliparity was 18%. In adjusted models, carotid distensibility coefficient was 0.09 × 10−5Pa−1 lower (p = 0.009) in parous vs. nulliparous women. Among parous women, there was a nonlinear association with the greatest carotid DC seen in women with 2 live births, and significantly lower distensibility seen in primiparas (p=0.04) or with higher parity > 2 (p=0.005). No such pattern of association with parity was found for lumen diameter or cIMT.
Parity is associated with lower carotid artery distensibility, suggesting arterial remodeling that lasts beyond childbirth. These long-term effects on the vasculature may explain the association of parity with cardiovascular events later in life.
doi:10.1161/HYPERTENSIONAHA.114.03285
PMCID: PMC4184976  PMID: 24842921
common carotid artery; arterial stiffness; carotid intima-media thickness; women; pregnancy
18.  Race/Ethnic Differences in the Associations of the Framingham Risk Factors with Carotid IMT and Cardiovascular Events 
PLoS ONE  2015;10(7):e0132321.
Background
Clinical manifestations and outcomes of atherosclerotic disease differ between ethnic groups. In addition, the prevalence of risk factors is substantially different. Primary prevention programs are based on data derived from almost exclusively White people. We investigated how race/ethnic differences modify the associations of established risk factors with atherosclerosis and cardiovascular events.
Methods
We used data from an ongoing individual participant meta-analysis involving 17 population-based cohorts worldwide. We selected 60,211 participants without cardiovascular disease at baseline with available data on ethnicity (White, Black, Asian or Hispanic). We generated a multivariable linear regression model containing risk factors and ethnicity predicting mean common carotid intima-media thickness (CIMT) and a multivariable Cox regression model predicting myocardial infarction or stroke. For each risk factor we assessed how the association with the preclinical and clinical measures of cardiovascular atherosclerotic disease was affected by ethnicity.
Results
Ethnicity appeared to significantly modify the associations between risk factors and CIMT and cardiovascular events. The association between age and CIMT was weaker in Blacks and Hispanics. Systolic blood pressure associated more strongly with CIMT in Asians. HDL cholesterol and smoking associated less with CIMT in Blacks. Furthermore, the association of age and total cholesterol levels with the occurrence of cardiovascular events differed between Blacks and Whites.
Conclusion
The magnitude of associations between risk factors and the presence of atherosclerotic disease differs between race/ethnic groups. These subtle, yet significant differences provide insight in the etiology of cardiovascular disease among race/ethnic groups. These insights aid the race/ethnic-specific implementation of primary prevention.
doi:10.1371/journal.pone.0132321
PMCID: PMC4489855  PMID: 26134404
19.  Common carotid artery intima-media thickness (IMT) progression as a predictor of stroke in MESA (Multi-Ethnic Study of Atherosclerosis) 
Background
Carotid artery intima-media thickness (IMT) is a marker of cardiovascular disease associated with incident stroke. We study whether IMT rate-of-change is associated with stroke.
Materials and Methods
We studied 5028 participants of the Multi-Ethnic Study of Atherosclerosis (MESA) composed of whites, Chinese, Hispanic and African-Americans free of cardiovascular disease. In this MESA IMT progression study, IMT rate-of-change (mm/year) was the difference in right common carotid artery (CCA) far-wall IMT (mm) divided by the interval between two ultrasound examinations (median interval of 32 months). CCA IMT was measured in a region free of plaque. Cardiovascular risk factors and baseline IMT were determined when IMT rate-of-change was measured. Multivariable Cox proportional hazards models generated Hazard risk Ratios (HR) with cardiovascular risk factors, ethnicity and education level/income as predictors.
Results
There were 42 first time strokes seen during a mean follow-up of 3.22 years (median 3.0 years). Average age was 64.2 years, with 48% males. In multivariable models, age (HR: 1.05 per year), systolic blood pressure (HR 1.02 per mmHg), lower HDL cholesterol levels (HR: 0.96 per mg/dL) and IMT rate-of-change (HR 1.23 per 0.05 mm/year; 95% C.L. 1.02, 1.48) were significantly associated with incident stroke. The upper quartile of IMT rate-of-change had an HR of 2.18 (95% C.L.: 1.07, 4.46) compared to the lower three quartiles combined.
Conclusion
Common carotid artery IMT progression is associated with incident stroke in this cohort free of prevalent cardiovascular disease and atrial fibrillation at baseline.
doi:10.1161/STROKEAHA.111.625186
PMCID: PMC3202068  PMID: 21885840
Ultrasonography; Risk Factors; Carotid Arteries; Carotid Intima Media Thickness; stroke
20.  Associations of cardiovascular risk factors, carotid intima-media thickness and left ventricular mass with inter-adventitial diameters of the common carotid artery: the Multi-Ethnic Study of Atherosclerosis (MESA) 
Atherosclerosis  2011;218(2):344-349.
Background
Common carotid artery inter-adventitial diameter (IAD) and intima-media thickness (IMT) are measurable by ultrasound. IAD may be associated with left ventricular mass (LV mass) while IMT is a marker of subclinical atherosclerosis. It is not clear if IAD is associated with LV mass after accounting for IMT and traditional cardiovascular risk factors.
Methods
IAD and IMT were measured on participants of the Multi-Ethnic Study of Atherosclerosis (MESA) IMT progression study. A total of 5641 of the originally enrolled 6814 MESA participants were studied. LV mass was measured by magnetic resonance imaging. Multivariable linear regression was used with IAD as the outcome and adjustment for risk factors, as well as IMT and LV mass.
Results
Traditional cardiovascular risk factors, height, weight and ethnicity were significantly associated with IAD. After adjustment for risk factors, a one mm difference in IMT was associated with a 1.802 mm (95% CI: 1.553, 2.051) higher mean IAD. A one gm difference in LV mass was associated with a 0.006 mm (95% CI: 0.005, 0.007) higher mean IAD. LV mass was independently associated with IAD after adjusting for cardiovascular risk factors and IMT. These associations were slightly different for men and women.
Conclusions
Inter-adventitial diameters are associated with left ventricular mass after adjusting for cardiovascular risk factors and IMT. IAD might serve as a surrogate for left ventricular mass and have predictive value for cardiovascular outcomes.
doi:10.1016/j.atherosclerosis.2011.05.033
PMCID: PMC3186064  PMID: 21726862
carotid arteries; ultrasonics; hypertrophy; magnetic resonance imaging; remodeling; risk factors; left ventricle
21.  Relationship of Change in Traditional Cardiometabolic Risk Factors to Change in Coronary Artery Calcification Among Individuals with Detectable Subclinical Atherosclerosis: The Multi-Ethnic Study of Atherosclerosis 
Background/Objectives
Data describing relationships between change in risk factors and coronary artery calcification (CAC) are lacking and could inform optimal cardiovascular disease prevention and treatment strategies. This study aimed to examine how change in traditional cardiometabolic risk factors related to change in CAC among individuals with detectable subclinical atherosclerosis.
Methods
Latent growth modeling was used to examine change in cardiometabolic risk factors (waist circumference, body mass index, systolic and diastolic blood pressure, high- and low-density lipoprotein cholesterol, triglycerides, and glucose) related to change in CAC up to an average 4.9-year follow-up in a multi-ethnic cohort of 3,398 asymptomatic individuals (57.8% men) who had detectable CAC (score > 0) at baseline, adjusting for baseline risk factor levels and CAC values, age, gender, race/ethnicity, smoking, family history of CVD, income, and use of antihypertensive, lipid-lowering, and glucose-lowering medications.
Results
Greater declines in blood pressure (systolic and diastolic) and low-density lipoprotein cholesterol at follow-up were each associated with greater CAC progression. The observed inverse associations were attributable to greater CAC progression in participants taking antihypertensive and lipid-lowering drugs who, as expected, had declines in blood pressure and lipid levels, respectively. These inverse associations did not emerge in participants not taking these medications.
Conclusions
Among individuals with subclinical atherosclerosis, the unexpected inverse associations observed between change in blood pressure and lipid levels with CAC progression emphasize the importance of considering medication use, and, when feasible, the severity and duration of disease, in exploring associations between risk factors and CAC change.
doi:10.1016/j.ijcard.2014.03.137
PMCID: PMC4060615  PMID: 24698232
risk factors; coronary artery calcification; atherosclerosis
22.  Systemic inflammation and cardiovascular risk factors predict rapid progression of atherosclerosis in rheumatoid arthritis 
Annals of the rheumatic diseases  2014;74(6):1118-1123.
Objective
To estimate atherosclerosis progression and identify influencing factors in rheumatoid arthritis (RA).
Methods
We used carotid ultrasound to measure intima-media thickness (IMT) in RA patients, and ascertained cardiovascular (CV) risk factors, inflammation markers and medications. A second ultrasound was performed approximately 3 years later. We calculated the progression rate by subtracting the baseline from the follow-up IMT, divided by the time between the two scans. We used logistic regression to identify baseline factors predictive of rapid progression. We tested for interactions of erythrocyte sedimentation rate (ESR) with CV risk factors and medication use.
Results
Results were available for 487 RA patients. The mean (SD) common carotid IMT at baseline was 0.571 mm (0.151). After a mean of 2.8 years, the IMT increased by 0.050 mm (0.055), p≤0.001, a progression rate of 0.018 mm/year (95% CI 0.016 to 0.020). Baseline factors associated with rapid progression included the number of CV risk factors (OR 1.27 per risk factor, 95% CI 1.01 to 1.61), and the ESR (OR 1.12 per 10 mm/h, 95% CI 1.02 to 1.23). The ESR×CV risk factor and ESR×medication product terms were significant, suggesting these variables modify the association between the ESR and IMT progression.
Conclusions
Systemic inflammation and CV risk factors were associated with rapid IMT progression. CV risk factors may modify the role of systemic inflammation in determining IMT progression over time. Methotrexate and antitumour necrosis factor agents may influence IMT progression by reducing the effect of the systemic inflammation on the IMT.
doi:10.1136/annrheumdis-2013-205058
PMCID: PMC4239202  PMID: 24845391
23.  Changes in Carotid Intima-Media Thickness During the Cardiac Cycle: The Multi-Ethnic Study of Atherosclerosis 
Background
Common carotid artery intima-media thickness (IMT), a measure of subclinical cardiovascular disease, changes during the cardiac cycle. The magnitude of this effect and its implications have not been well studied.
Methods and Results
Far-wall IMT measurements of the right common carotid artery were measured at end diastole and peak systole in 5633 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA). Multivariable regression models were generated with end-diastolic IMT, peak-systolic IMT, and change in IMT during the cardiac cycle as dependent variables and traditional cardiovascular risk factors as independent variables. The average age of our population was 61.9 (45 to 84) years. Average change in carotid IMT during the cardiac cycle was 0.041 mm (95% confidence interval: 0.039 to 0.042 mm), with a mean IMT of 0.68 mm. End-diastolic IMT and peak-systolic IMT were similarly associated with risk factors. In a fully adjusted model, change in carotid IMT during the cardiac cycle was associated with ethnicity and pulse pressure (P=0.001) and not age, sex, or other risk factors. Chinese and Hispanics had less of a change in IMT than did non-Hispanic whites. With peak-systolic IMT reference values used as normative data, 31.3% more individuals were classified as being in the upper quartile of IMT and at high risk for cardiovascular disease than would be expected when IMT is measured at end diastole.
Conclusions
Measurable differences in IMT are seen during the cardiac cycle. This affects the interpretation of IMT measurements used for cardiovascular risk assessment, given published normative data with IMT measured at peak systole.
Clinical Trial Registration
URL: www.ClinicalTrials.gov. Unique identifier: NCT00063440. (J Am Heart Assoc. 2012;1:e001420 doi: 10.1161/JAHA.112.001420.)
doi:10.1161/JAHA.112.001420
PMCID: PMC3487346  PMID: 23130162
atherosclerosis; blood pressure; carotid arteries; diastole; epidemiology; risk factors; systole; ultrasonics
24.  Associations of edge detected and manual traced common carotid intima-media thickness (IMT) measurements with Framingham risk factors: the Multi-Ethnic Study of Atherosclerosis 
Background
Carotid intima-media thickness (IMT) is a marker of cardiovascular disease derived from ultrasound images of the carotid artery. In most outcome studies, human readers identify and trace the key IMT interfaces. We evaluate an alternate approach using automated edge detection.
Methods
We study a subset of 5640 participants with an average age 61.7 years (48% men) of the Multi-Ethnic Study of Atherosclerosis composed of whites, Chinese, Hispanic and African-Americans that are part of the MESA IMT progression study. Manual tracing IMT (mt_IMT) and edge-detected IMT (ed_IMT) measurements of the far wall of the common carotid artery (CCA) served as outcome variables for multivariable linear regression models using Framingham cardiovascular risk factors and ethnicity as independent predictors.
Results
Measurements of mt_IMT was obtainable in 99.9% (5633/5640) and of ed_IMT in 98.9% (5579/5640) of individuals. Average ed_IMT was 0.19 mm larger than mt_IMT. Inter-reader systematic differences (bias) in IMT measurements were apparent for mt_IMT but not ed_IMT. Based on complete data on 5538 individuals, associations of IMT with risk factors were stronger (p < 0.0001) for mt_IMT (model r2: 19.5%) than ed_IMT (model r2: 18.5%).
Conclusion
We conclude that this edge-detection process generates IMT values equivalent to manually traced ones since it preserves key associations with cardiovascular risk factors. It also decreases inter-reader bias, potentially making it applicable for use in cardiovascular risk assessment.
doi:10.1161/STROKEAHA.110.603449
PMCID: PMC3169166  PMID: 21546477
Ultrasonography; Risk Factors; Carotid Arteries; Carotid Intima Media Thickness
25.  Cardiovascular Disease-Risk Markers in HIV Patients 
Objectives
HIV-positive patients have an increased risk for CVD; however, the underlying mechanisms are not well understood. Our goal was to assess traditional and emerging CVD-risk factors in the CARE Study, a well-described cohort of HIV-infected adults.
Methods
We analyzed demographic and clinical (viral load, CD4 count, ART regimen, cIMT) data including markers of lipid and glucose homeostasis in 176 HIV-positive subjects receiving regular care for HIV infection.
Results
No significant association between cIMT and LDL-C level was observed. HIV patients had significantly lower level of the large α-1 HDL particles and about 3-fold higher level of the small pre β-1 HDL particles than the normal population, but these parameters were not significantly associated with cIMT. Components of the metabolic syndrome, high TG/low HDL-C, insulin resistance and high BMI, as well as viral load were significant but moderate contributors to increased cIMT.
Conclusion
The major lipid disorder was low HDL-C and high TG level in this HIV-positive cohort. LDL-C was not elevated. These and previously published data indicate that HIV infection and HIV medications influence CVD risk by impairing cholesterol removal (efflux) via ABCA1 from macrophages. Decreasing CVD risk in HIV patients, with impaired cholesterol efflux from macrophages, may require a lower LDL-C goal than recommended for HIV-negative patients and also a better control of TG level.
doi:10.4172/2155-6113.1000317
PMCID: PMC4439003  PMID: 26005590
HIV; CVD risk; ART

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