Nonalcoholic fatty liver disease (NAFLD) is a common liver disease. Data is emerging that an independent association between markers of subclinical atherosclerosis and NAFLD exists and it may be considered as an independent predictor of cardiovascular (CV) outcomes. We aim to better characterize the relationship between NAFLD and inflammatory markers in a multi-ethnic cohort by assessing fatty liver on computed tomography (CT) scans.
The Multi-Ethnic Study of Atherosclerosis (MESA) is a longitudinal, population-based study from four ethnic groups free of CV disease at baseline. The inflammatory markers studied include: C-reactive protein (CRP) and interleukin 6 (IL-6). On CT scans liver-to-spleen ratio (LSR: Hounsfield Units (HU) of the liver divided by HU of spleen) of <1 and liver attenuation of <40 HU were used as criteria for fatty liver. Unadjusted and adjusted multivariate linear and logistic regression analysis was performed.
4038 participants amongst 6814 MESA population with visible spleen on the CT scan, available CRP and IL-6 levels and no reported liver cirrhosis were included. The average age was 61 +/− 10 years, 37% Caucasians and 45% were males. Mean CRP and IL-6 were 2.36 mg/dl and 1.37 pg/ml respectively. 696 participants (17%) had LSR of <1 and 253 (6%) had liver attenuation of <40 HU. When using LSR <1 as a continuous variable, the correlation (adjusted odds ratio (OR)) with CRP >2.0 was 0.037 (95% CI: 0.02-0.054) and with IL-6 was 0.014 (95% CI: 0.004-0.023). On the other hand when presence and absence of LSR <1 was considered, higher ORs for association with CRP >2: 1.41 (95% CI: 1.16 to 1.73) and IL6:1.18 (95% CI: 1.05 to 1.31) were found. Similarly, the adjusted association of per unit decrease in liver attenuation with CRP>2 was 1.92 (95% CI: 1.20 to 2.63) while for IL-6 was 1.08 (95% CI: 0.69 to 1.47). When considering presence and absence of liver attenuation <40 HU the OR for CRP >2 was 2.27 (95% CI: 1.62 to 3.16) and for IL-6 was 1.33 (95% CI: 1.13 to 1.58).
CRP and IL-6 levels were found to be significantly associated with liver fat assessed on CT scan after adjusting for other risk factors for atherosclerosis.
Inflammation; Non-alcoholic fatty liver disease; computed tomography scan; C reactive protein
Worldwide clinical practice guidelines for dyslipidemia emphasize allocating statin therapy to those at the highest absolute atherosclerotic cardiovascular disease (CVD) risk.
Methods and Results
We examined 5,534 MESA participants who were not on baseline medications for dyslipidemia. Participants were classified by baseline CAC score (>0, ≥100) and the common clinical scheme of counting lipid abnormalities (LA), including LDL-C ≥3.36 mmol/L (130 mg/dL), HDL-C <1.03 mmol/L (40 mg/dL) for men or <1.29 mmol/L (50 mg/dL) for women, and triglycerides ≥1.69 mmol/L (150 mg/dL). Our main outcome measure was incident CVD (myocardial infarction, angina resulting in revascularization, resuscitated cardiac arrest, stroke, cardiovascular death). Over a median follow-up of 7.6 years, more than half of events (55%) occurred in the 21% of participants with CAC≥100. Conversely, 65% of events occurred in participants with zero or one LA. In those with CAC≥100, CVD rates ranged from 22.2 to 29.2 per 1,000 person-years across LA categories. In contrast, with CAC=0, CVD rates ranged from 2.4 to 6.2 per 1,000 person-years across LA categories. Individuals with zero LA and CAC≥100 had a higher event rate compared to individuals with three LA but CAC=0 (22.2 vs 6.2 per 1,000 person-years). Similar results were obtained when classifying LA using dataset-quartiles of TC/HDL-C, LDL-C, non-HDL-C, or LDL particle concentration and guideline-categories of LDL-C or non-HDL-C.
CAC may have the potential to help match statin therapy to absolute CVD risk. Across the spectrum of dyslipidemia, event rates similar to secondary prevention populations were observed for patients with CAC≥100.
Atherosclerosis; Cardiovascular disease risk factors; Cholesterol; Computed tomography
Decreased arterial compliance is an early manifestation of adverse structural and functional changes within the vessel wall. Its correlation with left ventricular (LV) area on computed tomography (CT), a marker of LV remodeling, has not been well demonstrated. We tested the hypothesis that decreasing aortic compliance and increasing arterial stiffness is independently associated with increased LV area. The study population consisted of 3,540 (61±10 years, 46% men) from the MESA study who underwent aortic distensibility (AD) assessment on magnetic resonance imaging (MRI) and LV area measurement on CT (adjusted to body surface area). Multivariable logistic regression was performed to assess the association between body surface area (BSA) normalized LV area >75th percentile and AD after adjusting for baseline clinical, historical and imaging covariates. The mean LV area /BSA was 2,153 cm2 and mean AD was 1.84 mm Hg−1 x103. Subjects in the lowest AD quartile were older with higher prevalence of hypertension, diabetes, and hypercholesterolemia (p<0.05 for all comparisons). Using multivariate linear regression adjusting for demographics, traditional risk factors, coronary artery calcium and C-reactive protein, each standard deviation decrease was associated with 18 cm2 increase in the LV area. In addition, decreasing AD quartiles were independently associated with increased BSA LV area defined as >75th percentile. In this multi-ethnic cohort, reduced AD was associated with increased LV area. Longitudinal studies are needed to determine if decreased distensibility precedes and directly influences increased LV area.
Arterial compliance; Left ventricular area; Computed tomography; Aortic Distensibility
The newly released 2013 ACC/AHA Guidelines for Assessing Cardiovascular Risk makes progress compared with previous cardiovascular risk assessment algorithms. For example, the new focus on total atherosclerotic cardiovascular diseases (ASCVD) is now inclusive of stroke in addition to hard coronary events, and there are now separate equations to facilitate estimation of risk in non-Hispanic white and black individuals and separate equations for women. Physicians may now estimate lifetime risk in addition to 10-year risk. Despite this progress, the new risk equations do not appear to lead to significantly better discrimination than older models. Because the exact same risk factors are incorporated, using the new risk estimators may lead to inaccurate assessment of atherosclerotic cardiovascular risk in special groups such as younger individuals with unique ASCVD risk factors. In general, there appears to be an overestimation of risk when applied to modern populations with greater use of preventive therapy, although the magnitude of overestimation remains unclear. Because absolute risk estimates are directly used for treatment decisions in the new cholesterol guidelines, these issues could result in overuse of pharmacologic management. The guidelines could provide clearer direction on which individuals would benefit from additional testing, such as coronary calcium scores, for more personalized preventive therapies. We applaud the advances of these new guidelines, and we aim to critically appraise the applicability of the risk assessment tools so that future iterations of the estimators can be improved to more accurately assess risk in individual patients.
coronary artery calcium; guidelines; preventive cardiology; risk assessment
Heart rate (HR) at rest is associated with adverse cardiovascular events; however, the biologic mechanism for the relation is unclear. We hypothesized a strong association between HR at rest and subclinical inflammation, given their common interrelation with the autonomic nervous system. HR at rest was recorded at baseline in the Multi-Ethnic Study of Atherosclerosis, a cohort of 4 racial or ethnic groups without cardiovascular disease at baseline and then divided into quintiles. Subclinical inflammation was measured using high-sensitivity C-reactive protein, interleukin-6, and fibrinogen. We used progressively adjusted regression models with terms for physical activity and atrioventricular nodal blocking agents in the fully adjusted models. We examined inflammatory markers as both continuous and categorical variables using the clinical cut point of ≥3 mg/L for high-sensitivity C-reactive protein and the upper quartiles of fibrinogen (≥389 mg/dl) and interleukin-6 (≥1.89 pg/ml). Participants had a mean age of 62 years (SD 9.7), mean resting heart rate of 63 beats/min (SD 9.6) and were 47% men. Increased HR at rest was significantly associated with higher levels of all 3 inflammatory markers in both continuous (p for trend <0.001) and categorical (p for trend <0.001) models. Results were similar among all 3 inflammatory markers, and there was no significant difference in the association among the 4 racial or ethnic groups. In conclusion, an increased HR at rest was associated with a higher level of inflammation among an ethnically diverse group of subjects without known cardiovascular disease.
Obstructive sleep apnea is associated with hypertension, inflammation, and increased cardiovascular risk. Continuous positive airway pressure (CPAP) reduces blood pressure, but adherence is often suboptimal, and the benefit beyond management of conventional risk factors is uncertain. Since intermittent hypoxemia may underlie cardiovascular sequelae of sleep apnea, we evaluated the effects of nocturnal supplemental oxygen and CPAP on markers of cardiovascular risk.
We conducted a randomized, controlled trial in which patients with cardiovascular disease or multiple cardiovascular risk factors were recruited from cardiology practices. Patients were screened for obstructive sleep apnea with the use of the Berlin questionnaire, and home sleep testing was used to establish the diagnosis. Participants with an apnea–hypopnea index of 15 to 50 events per hour were randomly assigned to receive education on sleep hygiene and healthy lifestyle alone (the control group) or, in addition to education, either CPAP or nocturnal supplemental oxygen. Cardiovascular risk was assessed at baseline and after 12 weeks of the study treatment. The primary outcome was 24-hour mean arterial pressure.
Of 318 patients who underwent randomization, 281 (88%) could be evaluated for ambulatory blood pressure at both baseline and follow-up. On average, the 24-hour mean arterial pressure at 12 weeks was lower in the group receiving CPAP than in the control group (−2.4 mm Hg; 95% confidence interval [CI], −4.7 to −0.1; P = 0.04) or the group receiving supplemental oxygen (−2.8 mm Hg; 95% CI, −5.1 to −0.5; P = 0.02). There was no significant difference in the 24-hour mean arterial pressure between the control group and the group receiving oxygen. A sensitivity analysis performed with the use of multiple imputation approaches to assess the effect of missing data did not change the results of the primary analysis.
In patients with cardiovascular disease or multiple cardiovascular risk factors, the treatment of obstructive sleep apnea with CPAP, but not nocturnal supplemental oxygen, resulted in a significant reduction in blood pressure. (Funded by the National Heart, Lung, and Blood Institute and others; HeartBEAT ClinicalTrials.gov number, NCT01086800.)
Decreased arterial distensibility is an early manifestation of adverse structural and functional changes within the vessel wall. Its correlation with thoracic aortic calcium (TAC), a marker of atherosclerosis, has not been well demonstrated. We tested the hypothesis that decreasing aortic compliance and increasing arterial stiffness is independently associated with increased TAC. We included 3,540 (61±10 years, 46% males) subjects from the Multi-ethnic Study of Atherosclerosis (MESA) study who underwent aortic distensibility (AD) assessment on MRI. TAC was calculated using modified Agatston algorithm on non-contrast cardiac CT. Multivariate regression models were calculated for the presence of TAC. Overall, 861 (24%) individuals had detectable TAC. A lower AD was observed among those with vs. without TAC (2.02±1.34 vs. 1.28±0.74, p<0.0001). The prevalence of TAC increased significantly across decreasing quartiles of AD (7%, 17%, 31%, and 42%, p<0.0001). Using multivariate analysis, TAC was independently associated with AD after adjusting for age, gender, ethnicity and other covariates. In conclusion, our analysis demonstrates that increased arterial stiffness is associated with increased TAC independent of ethnicity and other atherosclerotic risk factors.
In clinical and research settings worldwide, low-density lipoprotein cholesterol (LDL-C) is typically estimated using the Friedewald equation. This equation assumes a fixed factor of 5 for the ratio of triglycerides to very low-density lipoprotein cholesterol (TG:VLDL-C); however, the actual TG:VLDL-C ratio varies significantly across the range of triglyceride and cholesterol levels.
To derive and validate a more accurate method for LDL-C estimation from the standard lipid profile using an adjustable factor for the TG:VLDL-C ratio.
DESIGN, SETTING, AND PARTICIPANTS
We used a convenience sample of consecutive clinical lipid profiles obtained from 2009 through 2011 from 1 350 908 children, adolescents, and adults in the United States. Cholesterol concentrations were directly measured after vertical spin density-gradient ultracentrifugation, and triglycerides were directly measured. Lipid distributions closely matched the population-based National Health and Nutrition Examination Survey (NHANES). Samples were randomly assigned to derivation (n = 900 605) and validation (n = 450 303) data sets.
MAIN OUTCOMES AND MEASURES
Individual patient-level concordance in clinical practice guideline LDL-C risk classification using estimated vs directly measured LDL-C (LDL-CD).
In the derivation data set, the median TG:VLDL-C was 5.2 (IQR, 4.5–6.0). The triglyceride and non–high-density lipoprotein cholesterol (HDL-C) levels explained 65% of the variance in the TG:VLDL-C ratio. Based on strata of triglyceride and non–HDL-C values, a 180-cell table of median TG:VLDL-C values was derived and applied in the validation data set to estimate the novel LDL-C (LDL-CN). For patients with triglycerides lower than 400 mg/dL, overall concordance in guideline risk classification with LDL-CD was 91.7% (95% CI, 91.6%–91.8%) for LDL-CN vs 85.4% (95% CI, 85.3%–85.5%) for Friedewald LDL-C (LDL-CF) (P < .001). The greatest improvement in concordance occurred in classifying LDL-C lower than 70 mg/dL, especially in patients with high triglyceride levels. In patients with an estimated LDL-C lower than 70 mg/dL, LDL-CD was also lower than 70 mg/dL in 94.3% (95% CI, 93.9%–94.7%) for LDL-CN vs 79.9% (95% CI, 79.3%–80.4%) for LDL-CF in samples with triglyceride levels of 100 to 149 mg/dL; 92.4% (95% CI, 91.7%–93.1%) for LDL-CN vs 61.3% (95% CI, 60.3%–62.3%) for LDL-CF in samples with triglyceride levels of 150 to 199 mg/dL; and 84.0% (95% CI, 82.9%–85.1%) for LDL-CN vs 40.3% (95% CI, 39.4%–41.3%) for LDL-CF in samples with triglyceride levels of 200 to 399 mg/dL (P < .001 for each comparison).
CONCLUSIONS AND RELEVANCE
A novel method to estimate LDL-C using an adjustable factor for the TG:VLDL-C ratio provided more accurate guideline risk classification than the Friedewald equation. These findings require external validation, as well as assessment of their clinical importance. The implementation of these findings into clinical practice would be straightforward and at virtually no cost.
clinicaltrials.gov Identifier: NCT01698489
Current literature has elucidated a new phenotype, metabolically healthy obese (MHO), with risks of cardiovascular disease similar to that of normal weight individuals. Few studies have examined the MHO phenotype in an aging population, especially in association with subclinical CVD.
Research design and methods
This cross sectional study population consisted of 208 octogenarians and older. Anthropometrics, biochemical, and radiological parameters were measured to assess obesity, metabolic health (assessed by the National Cholesterol Education Program –Adult Treatment Panel (NCEP-ATP III) criteria), and subclinical measures of CVD.
The prevalence of MHO was 13.5% (N = 28). No significant association with MHO was noted for age, coronary artery calcium score, cIMT, or hs-CRP > 3 mg/dl (p = NS).
Our results suggest that the MHO phenotype exists in the elderly; however, subclinical CVD measures were not different in sub-group analysis suggesting traditional metabolic risk factor algorithms may not be accurate in the very elderly.
Obesity; Aging; Metabolic Syndrome; Subclinical CVD
Current clinical guidelines recommend the use of a global risk assessment tool, such as those pioneered by the Framingham Heart Study, to determine eligibility for statin therapy in patients with absolute risk levels greater than a certain threshold. In support of this approach, several randomized trials have reported that patients with high absolute risk clearly benefit from statin therapy. Therefore, the guideline recommendations would seem intuitive and effective, albeit on the core assumption that the mortality and morbidity benefits associated with statin therapy would be greatest in those with high predicted absolute risk. However, if this assumption is incorrect, using predicted absolute risk to guide statin therapy could easily result in underuse in some groups and overuse in others. Herein, the authors question the utility of global risk assessment strategies based on the Framingham risk score for guiding statin therapy in light of current data that have become available from more recent and robust prospective randomized clinical trials since the publication of the National Cholesterol Education Program Adult Treatment Panel III guidelines. Moreover, the Adult Treatment Panel III guidelines do not support treatment of some patients who may benefit from statin therapy. In conclusion, the authors propose an alternative approach for incorporating more recent randomized trial data into future statin allocation algorithms and treatment guidelines.
We assess the improvement in discrimination afforded by the addition thoracic aorta calcium (TAC), aortic valve calcification (AVC), mitral annular calcification (MAC), pericardial adipose tissue volume (PAT) and liver attenuation (LA) to Framingham risk score(FRS) + coronary artery calcium (CAC) for incident CHD/CVD in a multi ethnic cohort.
Methods and Results
A total 5745(2710 were intermediate Framingham risk, 210 CVD and 155 CHD events) 251 had adjudicated CHD, 346 had CVD events, 321 died after 9 years of follow-up. Cox proportional hazard, receiver operator curve (ROC) and net reclassification improvement (NRI) analyses.
In the whole cohort and also when the analysis was restricted to only the intermediate risk participants: CAC, TAC, AVC and MAC were all significantly associated with incident CVD/CHD/ mortality; CAC had the strongest association. When added to the FRS, CAC had the highest area under the curve (AUC) for the prediction of incident CHD/CVD; LA had the least. The addition of TAC, AVC, MAC, PAT and LA to FRS + CAC all resulted in a significant reduction in AUC for incident CHD [0.712 vs. 0.646, 0.655, 0.652, 0.648 and 0.569; all p<0.01 respectively] in participants with intermediate FRS. The addition of CAC to FRS resulted in an NRI of 0.547 for incident CHD in the intermediate risk group. The NRI when TAC, AVC, MAC, PAT and LA were added to FRS + CAC were 0.024, 0.026, 0.019, 0.012 and 0.012 respectively, for incident CHD in the intermediate risk group. Similar results were obtained for incident CVD in the intermediate risk group and also when the whole cohort was used instead of the intermediate FRS group.
The addition of CAC to the FRS provides superior discrimination especially in intermediate risk individuals compared with the addition of TAC, AVC, MAC, PAT or LA for incident CHD/CVD. Compared with FRS + CAC, the addition of TAC, AVC, MAC, PAT or LA individually to FRS + CAC worsens the discrimination for incident CHD/CVD. These CT risk markers are unlikely to be useful for improving cardiovascular risk prediction.
cardiac CT derived risk factors; coronary heart disease; cardiovascular events; risk prediction
Examine whether the coronary artery calcium score (CAC) can be used to define the target population to treat with a polypill.
Prior studies suggested a single polypill to reduce cardiovascular disease (CVD) at the population level.
Participants from the Multi-Ethnic Study of Atherosclerosis (MESA) were stratified using the criteria of four polypill studies (TIPS, Poly-Iran, Wald's, and the PILL collaboration). We compared coronary heart disease (CHD) and CVD event rates and calculated 5-year number needed to treat (NNT) after stratification based on the CAC score.
Among MESA participants eligible for the TIPS, Poly-Iran, Wald's and PILL collaboration, a CAC=0 was observed in 58.6%, 54.5%, 38.9% and 40.8%, respectively. The rate of CHD events among those with CAC=0 varied from 1.2 to 1.9 events per 1000 person-years, those with CAC 1- 100 had event rates ranging from 4.1 to 5.5, and in those with CAC>100 the event rate ranged from 11.6 to 13.3. The estimated 5-year NNT to prevent one CVD event ranged from 81 to 130 for individuals with CAC=0, 38 to 54 for those with CAC 1-100, and 18 to 20 for those with CAC>100.
Among individuals eligible for treatment with the polypill, the majority of events occurred in those with CAC>100. The group with CAC=0 had a very low event rate and a high projected NNT. The avoidance of treatment in individuals with CAC=0 could allow for significant reductions in the population considered for treatment, with a more selective use of the polypill and as a result, avoiding treatment in those who are unlikely to be benefit
subclinical atherosclerosis; risk stratification; polypill
Resting heart rate is an easily measured, non-invasive vital sign that is associated with cardiovascular disease events. The pathophysiology of this association is not known. We investigated the relationship between resting heart rate and stiffness of the carotid (a peripheral artery) and the aorta (a central artery) in an asymptomatic multi-ethnic population. Resting heart rate was recorded at baseline in the Multi-Ethnic Study of Atherosclerosis (MESA). Distensibility was used as a measure of arterial elasticity, with a lower distensibility indicating an increase in arterial stiffness. Carotid distensibility was measured in 6,484 participants (98% of participants) using B-mode ultrasound and aortic distensibility was measured in 3,512 participants (53% of participants) using cardiac MRI. Heart rate was divided into quintiles and we used progressively adjusted models that included terms for physical activity and AV-nodal blocking agents. Mean resting heart rate of participants (mean age 62 years, 47% male) was 63 beats per minute (SD 9.6 beats per minute). In unadjusted and fully adjusted models, carotid distensibility and aortic distensibility decreased monotonically with increasing resting heart rate (p for trend <0.001 and 0.009 respectively). The relationship was stronger for carotid versus aortic distensibility. Similar results were seen using the resting heart rate taken at the time of MRI scanning. Our results suggest that a higher resting heart rate is associated with an increased arterial stiffness independent of AV-nodal blocker use and physical activity level, with a stronger association for a peripheral (carotid) compared to a central (aorta) artery.
heart rate; cardiovascular disease; stiffness; ultrasound; cardiac magnetic resonance imaging
Coronary artery calcium (CAC) predicts coronary heart disease (CHD) events and serial measurement of CAC has been proposed to evaluate atherosclerosis progression. We examined whether progression of CAC is a predictor of future CHD events.
Methods and Results
We studied 6,778 persons (52.8% female) aged 45–84 years from the Multi-Ethnic Study of Atherosclerosis. 5,682 persons had baseline and follow-up CAC scans approximately 2.5 ± 0.8 years apart; multiple imputation was used to account for the remainder (n=1,096) missing follow-up scans. Median follow-up duration from the baseline was 7.6 (max=9.0) years. CAC change was assessed by absolute change between baseline and follow-up CAC. Cox proportional hazards regression providing hazard ratios (HR) examined the relation of change in CAC with CHD events, adjusting for age, gender, ethnicity, baseline calcium score, and other risk factors. 343 total and 206 hard CHD events occurred. The annual change in CAC averaged 24.9 ± 65.3 units. Among persons without CAC at baseline (n=3,396), a 5 unit annual change in CAC was associated with an adjusted HR of 1.4 (1.0–1.9) for total and 1.5 (1.1–2.1) for hard CHD. Among those with CAC>0 at baseline HR’s (per 100 unit annual change) were 1.2 (1.1–1.4) and 1.3 (1.1–1.5), respectively. Among participants with baseline CAC, those with annual progression of ≥300 units had adjusted HR’s of 3.8 (1.5–9.6) for total and 6.3 (1.9–21.5) for hard CHD compared to those without progression.
Progression of CAC is associated with an increased risk for future hard and total CHD events.
coronary calcification; atherosclerosis; imaging; coronary heart disease
Stiffening of the central elastic arteries is one of the earliest detectable manifestations of adverse change within the vessel wall. While an association between carotid artery stiffness and adverse events has been demonstrated, little is known about the relationship between stiffness and atherosclerosis. Even less is known about the impact of age, gender, and race on this association. To elucidate this question, we used baseline data from the Multi-Ethnic Study of Atherosclerosis (MESA, 2000-2002). Carotid artery distensibility coefficient (DC) was calculated after visualization of the instantaneous waveform of common carotid diameter using high resolution B-mode ultrasound. Thoracic aorta calcification (TAC) was identified using non-contrast cardiac CT. We found a strong association between decreasing DC (increasing carotid stiffness) and increasing TAC as well as a graded increase in TAC score (p<0.001). After controlling for age, gender, race, and traditional and emerging cardiovascular risk factors, individuals in the stiffest quartile had a prevalence ratio of 1.52 (95% CI 1.15-2.00) for TAC compared to the least stiff quartile. In exploratory analysis, carotid stiffness was more highly correlated with calcification of the aorta than calcification of the coronary arteries (ρ=0.32 vs. 0.22, p<0.001 for comparison). In conclusion, there is a strong independent association between carotid stiffness and thoracic aorta calcification. Carotid stiffness is more highly correlated with calcification of the aorta, a central elastic artery, than calcification of the coronary arteries. The prognostic significance of these findings requires longitudinal follow-up of the MESA cohort.
Carotid stiffness; carotid compliance; subclinical atherosclerosis; thoracic aorta calcification; coronary calcification
The presence and extent of coronary artery calcium (CAC) is an independent predictor of coronary heart disease (CHD) morbidity and mortality. Few studies have evaluated interactions or independent incremental risk for coronary and thoracic aortic calcification (TAC). The independent predictive value of TAC for CHD events is not well-established.
This study used risk factor and computed tomography scan data from 6,807 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Using the same images for each participant, TAC and CAC were each computed using the Agatston method. The study subjects were free of incident CHD at entry into the study.
The mean age of the study population (n=6807) was 62±10 years (47% males). At baseline, the prevalence of TAC and CAC was 28 % (1,904/6,809) and 50% (3393/6809), respectively. Over 4.5±0.9 years, a total of 232 participants (3.41%) had CHD events, of which 132 (1.94%) had a hard event (myocardial infarction, resuscitated cardiac arrest, or CHD death). There was a significant interaction between gender and TAC for CHD events (p<0.05). Specifically, in women, the risk of all CHD event was nearly 3-fold greater among those with any TAC (hazard ratio: 3.04, 95% CI; 1.60–5.76). After further adjustment for increasing CAC score, this risk was attenuated but remained robust (HR: 2.15, 95% CI: 1.10–4.17). Conversely, there was no significant association between TAC and incident CHD in men. In women, the likelihood ratio chi square statistics indicate that the addition of TAC contributed significantly to predicting incident CHD event above that provided by traditional risk factors alone (chi square= 12.44, p=0.0004) as well as risk factors + CAC scores (chi square= 5.33, p=0.02) . On the other hand, addition of TAC only contributed in the prediction of hard CHD events to traditional risk factors (chi-square=4.33, p=0.04) in women, without contributing to the model containing both risk factors and CAC scores (chi square=1.55, p=0.21).
Our study indicates that TAC is a significant predictor of future coronary events only in women, independent of CAC. On studies obtained for either cardiac or lung applications, determination of TAC may provide modest supplementary prognostic information in women with no extra cost or radiation.
atherosclerosis; cardiac CT; coronary calcium; multi-detector CT; prognosis; thoracic atherosclerosis
In this study, the authors determined the prevalence and extent of cardiovascular disease (CVD) risk factors and subclinical CVD in four US Hispanic subgroups, as well as associations between the CVD risk factors and subclinical CVD in these groups. Participants were 1,437 Hispanic men and women enrolled in the Multi-Ethnic Study of Atherosclerosis in 2000–2002. Fifty-six percent were Mexican-American, 12% were Dominican-American, 14% were Puerto Rican-American, and 18% were Other Hispanic-American. All participants underwent clinical examinations for coronary artery calcium, thoracic aortic calcium, carotid intimal-medial thickness, ankle-brachial index, left ventricular mass, and left ventricular size. Mexican Americans had the highest levels of coronary artery calcium, thoracic aortic calcium, and carotid intimal-medial thickness, while Puerto Rican Americans had the highest prevalence of an ankle-brachial index less than 1.0 and levels of left ventricular mass. The magnitudes of the associations between coronary artery calcium and age, sex, and body mass index were similar across all Hispanic subgroups. However, there were differences in the magnitude and significance of the associations between coronary artery calcium and hypertension, hypercholesterolemia, and cigarette smoking among the different Hispanic subgroups. This finding was also present for the other subclinical CVD measures. These results suggest a differential relationship between risk factors and either prevalence or extent of subclinical disease by Hispanic subgroup.
atherosclerosis; cardiovascular diseases; ethnic groups; Hispanic Americans; risk factors
We tested whether the association between bone mineral density (BMD) and coronary artery calcification (CAC) varies according to dyslipidemia in community-living individuals. Between 2002 and 2005, 305 women and 631 men (mean age of 64 years) and naïve to lipid-modifying medications and estrogen use were assessed for spine BMD, CAC, and total (TC), HDL- and LDL-cholesterol and triglycerides.
Random sample of participants from the Multi-Ethnic Study of Atherosclerosis (MESA) without clinical cardiovascular disease.
Spine BMD at the L3 vertebrate by computer tomography (CT).
CAC prevalence by CT.
Total cholesterol to HDL ratio (TC:HDL) ≥ 5.0.
The association of BMD with CAC differed in women with TC:HDL < 5.0 vs. higher (p-interaction =0.01). In age and race adjusted models, among women with TC:HDL < 5.0, each SD (43.4 mg/cc) greater BMD was associated with a 25% lower prevalence of CAC (Prevalence Ratio [PR] 0.75, 95% confidence interval [CI] 0.63–0.89), whereas among women with higher TC:HDL, higher BMD was not significantly associated with CAC (PR 1.22, 95% CI 0.82–1.82). Results were similar using other definitions of hyperlipidemia. In contrast, no consistent association was observed between BMD and CAC in men irrespective of the TC:HDL ratio (p interaction 0.54).
The inverse association of BMD with CAC is stronger in women without dyslipidemia. These data argue against the hypothesis that dyslipidemia is the key factor responsible for the inverse association of BMD with atherosclerosis.
We hypothesized increasing obstructive sleep apnea (OSA) severity would be associated with nondipping blood pressure (BP) in increased cardiovascular disease (CVD) risk.
Baseline data from 298 cardiology patients recruited for a multicenter randomized controlled trial were examined. Dipping was defined as a sleep-related BP or heart rate (HR) reduction of at least 10%. Logistic regression models were fit, adjusting for age, sex, race, BMI, CVD risk factors, CVD, and study site.
There was a statistically significant 4% increase in the odds of nondipping SBP per 1-unit increase in both Apnea Hypopnea Index (AHI) and Oxygen Desaturation Index (ODI). There was no significant relationship between AHI and nondipping mean arterial pressure (MAP); however, a 3% increase in the odds of nondipping MAP per 1-unit increase in ODI was observed (odds ratio, OR =1.03; 95% confidence interval, CI 1.00–1.05). At severe OSA levels, a 10 and 4% increase in odds of nondipping DBP per 1-unit increase in AHI and ODI were observed, respectively. A 6% [OR =1.06; 95% CI (1.01–1.10)] increase in nondipping HR odds was observed with each increase in ODI until the upper quartile of ODI.
In patients at cardiovascular risk and moderate-to-severe OSA, increasing AHI and/or ODI were associated with increased odds of nondipping SBP and nondipping MAP. More severe levels of AHI and ODI also were associated with nondipping DBP. These results support progressive BP burden associated with increased OSA severity even in patients managed by cardiology specialty care.
cardiovascular disease; hypertension; hypoxia; sleep apnea
This study sought to evaluate the relationship between microalbuminuria (MA) and the development and progression of atherosclerosis, as assessed by incident and progression of coronary artery calcification (CAC).
MA is associated with an increased risk of cardiovascular disease, but the mechanism by which MA imparts this increased risk is not known.
The MESA (Multi-Ethnic Study of Atherosclerosis) study is a prospective cohort study of 6,814 self-identified White, African-American, Hispanic, or Chinese participants free of clinical cardiovascular disease at entry. Of the 6,775 individuals with available urine albumin data, we excluded 97 subjects with macroalbuminuria and 1,023 with missing follow-up CAC data. The final study population consists of 5,666 subjects.
At baseline, individuals with MA were more likely to have CAC >0 compared with those without MA (62% vs. 48%, p < 0.0001). During a mean follow-up of 2.4 ± 0.8 years, those with MA and no CAC at baseline were more likely to develop CAC (relative risk [RR]: 2.05, 95% confidence interval [CI]: 1.41 to 3.02, p < 0.0001) as compared with those without MA in demographic-adjusted analyses. After multivariant adjustment, the relationship was attenuated but remained statistically significant (RR: 1.76, 95% CI: 1.19 to 2.61, p = 0.005). Among those with CAC at baseline, those with versus those without MA had a 15 (95% CI: 8 to 22, p < 0.0001) volume units higher median increase in CAC in demographic-adjusted analyses. After multivariant adjustment, MA remained associated with incident CAC (RR: 1.76, 95% CI: 1.19 to 2.61, p = 0.005) and with progression of CAC (median increase in CAC volume score of 9 [95% CI: 2 to 16, p = 0.009]), relative to those without MA.
This large multiethnic, population-based study of asymptomatic individuals demonstrates an increased risk of incident CAC as well as greater CAC progression among those with MA. Further study is needed to determine the degree to which MA precedes and predicts progression of atherosclerosis and how this information can be used to reduce cardiovascular events.
coronary artery calcium; microalbuminuria; risk prediction; coronary heart disease; Multi-Ethnic Study of Atherosclerosis
To compare the association of the Framingham Risk Score (FRS) and Reynolds Risk Score (RRS) with subclinical atherosclerosis, assessed by incidence and progression of coronary artery calcium (CAC).
The comparative effectiveness of competing risk algorithms for indentifying subclinical atherosclerosis is unknown.
The Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective cohort study of 6,814 participants free of baseline CVD. All participants underwent risk factor assessment, as well as baseline and follow-up CAC testing. We assessed the performance of the FRS and RRS to predict CAC incidence and progression using relative risk and robust linear regression.
The study population included 5,140 individuals (61±10 years, 47% males, mean follow-up: 3.1±1.3 years). Among 53% of subjects (n=2,729) with no baseline CAC, 18% (n=510) developed incident CAC. Both the FRS and RRS were significantly predictive of incident CAC [RR 1.40 (95% CI 1.29 – 1.52), and RR 1.41 (95% CI 1.30 – 1.54) per 5% increase in risk, respectively] and CAC progression [mean CAC score change 6.92 (95% CI 5.31 – 8.54) and 6.82 (95% CI 5.51 – 8.14) per 5% increase]. Discordance in risk category classification (< or > 10% 10-year CHD risk) occurred in 13.7%, with only the RRS consistently adding predictive value for incidence and progression of CAC. These subclinical atherosclerosis findings are supported by a CHD events analysis over 5.6±0.7 year follow-up.
Both the RRS and FRS predict onset and progression of subclinical atherosclerosis. However, the RRS may provide additional predictive information when discordance between the scoring systems exists.
coronary artery calcium progression; subclinical atherosclerosis; risk prediction; Reynolds Risk Score; Framingham Risk Score
Unhealthy lifestyle habits are a major contributor to coronary artery disease. The purpose of the present study was to investigate the associations of smoking, weight maintenance, physical activity, and diet with coronary calcium, cardiovascular events, and mortality. US participants who were 44–84 years of age (n = 6,229) were followed in the Multi-Ethnic Study of Atherosclerosis from 2000 to 2010. A lifestyle score ranging from 0 to 4 was created using diet, exercise, body mass index, and smoking status. Coronary calcium was measured at baseline and a mean of 3.1 (standard deviation, 1.3) years later to assess calcium progression. Participants who experienced coronary events or died were followed for a median of 7.6 (standard deviation, 1.5) years. Participants with lifestyle scores of 1, 2, 3, and 4 were found to have mean adjusted annual calcium progressions that were 3.5 (95% confidence interval (CI): 0.0, 7.0), 4.2 (95% CI: 0.6, 7.9), 6.8 (95% CI: 2.0, 11.5), and 11.1 (95% CI: 2.2, 20.1) points per year slower, respectively, relative to the reference group (P = 0.003). Unadjusted hazard ratios for death by lifestyle score were as follows: for a score of 1, the hazard ratio was 0.79 (95% CI: 0.61, 1.03); for a score of 2, the hazard ratio was 0.61 (95% CI: 0.46, 0.81); for a score of 3, the hazard ratio was 0.49 (95% CI: 0.32, 0.75); and for a score of 4, the hazard ratio was 0.19 (95% CI: 0.05, 0.75) (P < 0.001 by log-rank test). In conclusion, a combination of regular exercise, healthy diet, smoking avoidance, and weight maintenance was associated with lower coronary calcium incidence, slower calcium progression, and lower all-cause mortality over 7.6 years.
coronary artery disease; CT and MRI; diet; epidemiology; exercise; primary prevention; risk factors; weight reduction
While non-alcoholic fatty liver disease (NAFLD) is associated with the metabolic syndrome, it is not known if NAFLD plays an independent role in the atherogenic dyslipidemia phenotype.
Methods and Results
The Multi-Ethnic Study of Atherosclerosis (MESA) is a population-based prospective cohort study of adults free of clinical cardiovascular disease at enrollment. We tested for a relationship between NAFLD, defined as a liver/spleen (L/S) attenuation ratio of <1 on a non-contrast cardiac CT scan, and multiple measures of fasting serum lipoprotein size, cholesterol and particle concentrations.
NAFLD was present in 569 (17%) of 3,362 participants. After adjustment for multiple metabolic risk factors, adiposity and measures of insulin resistance (HOMA-IR), NAFLD was independently associated with higher fasting serum triglycerides and lower serum HDL-C. Despite a lack of association with LDL-C, NAFLD was associated with higher LDL particle concentration and lower LDL particle size. Modeling the L/S ratio as a continuous variable, a severity dependent association was observed between atherogenic lipoprotein abnormalities and NAFLD.
In a large, multi-ethnic, gender balanced cohort, CT-diagnosed NAFLD was associated with the atherogenic dyslipidemia phenotype in a dose dependent fashion. These relationships persisted after adjustment for several metabolic risk factors and HOMA-IR, suggesting a possible independent pathophysiologic role between NAFLD and dyslipidemia.
Nonalcoholic Fatty Liver Disease; Lipoproteins; MESA; NMR; cardiac CT scan
Coronary heart disease (CHD) incidence has declined significantly in the US, as have levels of major coronary risk factors, including LDL-cholesterol, hypertension and smoking, but whether trends in subclinical atherosclerosis mirror these trends is not known.
Methods and Findings
To describe recent secular trends in subclinical atherosclerosis as measured by serial evaluations of coronary artery calcification (CAC) prevalence in a population over 10 years, we measured CAC using computed tomography (CT) and CHD risk factors in five serial cross-sectional samples of men and women from four race/ethnic groups, aged 55–84 and without clinical cardiovascular disease, who were members of Multi-Ethnic Study of Atherosclerosis (MESA) cohort from 2000 to 2012. Sample sizes ranged from 1062 to 4837. After adjusting for age, gender, and CT scanner, the prevalence of CAC increased across exams among African Americans, whose prevalence of CAC was 52.4% in 2000–02, 50.4% in 2003–04, 60.0% is 2005–06, 57.4% in 2007–08, and 61.3% in 2010–12 (p for trend <0.001). The trend was strongest among African Americans aged 55–64 [prevalence ratio for 2010–12 vs. 2000–02, 1.59 (95% confidence interval 1.06, 2.39); p = 0.005 for trend across exams]. There were no consistent trends in any other ethnic group. Risk factors generally improved in the cohort, and adjustment for risk factors did not change trends in CAC prevalence.
There was a significant secular trend towards increased prevalence of CAC over 10 years among African Americans and no change in three other ethnic groups. Trends did not reflect concurrent general improvement in risk factors. The trend towards a higher prevalence of CAC in African Americans suggests that CHD risk in this population is not improving relative to other groups.
Obesity demonstrates a direct relation with cardiovascular risk and all-cause mortality, while cardiorespiratory fitness demonstrates an inverse relation. In clinical practice, several cardiometabolic (“CM”) risk factors are commonly measured to gauge cardiovascular risk yet the interaction between fitness and obesity with regard CM risk has not been fully explored. We studied 2,634 Brazilian adults referred for an employer-sponsored heath exam. Obesity was defined as BMI >30 kg/m2 or waist circumference > 102cm (men) or >88cm (women) when BMI 25–30kg/m2. Fitness was quantified by stage achieved on an Ellestad treadmill stress test, with those completing stage 4 considered fit. Hepatic steatosis was determined by ultrasound. We compared CM risk factors after stratifying patients into 4 groups: fit/normal weight, fit/obese, unfit/normal weight & unfit/obese. Approximately 22% of patients were obese; 12% were unfit. Fitness and obesity were moderately correlated (ρ=0.38–50). 6.5% of the sample was unfit/normal weight, and 16% fit/obese. In overweight and obese patients, fitness was negatively associated with CM risk (p<0.01 for all values). In fit patients, increasing BMI was positively associated with CM risk (p<0.01 for all values). In instances of discordance between fitness and obesity, obesity was the stronger determinant of CM risk. Fitness and obesity are independently associated with CM risk. The effects of fitness and obesity are additive but obesity is more strongly associated with CM risk when fitness and obesity are discordant. These findings underscore the need for weight loss in obese individuals and suggest an unmeasured benefit of fitness.
fitness; obesity; metabolic syndrome; liver fat; inflammation