Soluble intercellular adhesion molecule-1 (sICAM-1) is associated with endothelial dysfunction and clinical cardiovascular disease. We investigated the relationship of subclinical atherosclerosis with sICAM-1 concentration.
sICAM-1 concentration was assayed at year 15 of the Coronary Artery Risk Development in Young Adults (CARDIA) Study (black and white men and women, average age 40 years). We assessed progression of coronary artery calcification through year 20 (CAC, n=2378), and both carotid artery stenosis (n=2432) and intima media thickness at year 20 (IMT, n = 2240).
Median sICAM-1 was 145.9 ng/ml. Among a subgroup with advanced atherosclerotic plaque (either CAC or stenosis), IMT was 0.010 (95% confidence interval (CI) 0.003–0.017 mm) higher per standard deviation of sICAM-1 (44 ng/ml) in a model adjusted for age, race, sex, clinic, smoking, exercise, body size, education, blood pressure, antihypertensive medication, plasma lipids, and cholesterol lowering medication. With the same adjustment, the odds ratios (OR) for the presence of year 20 carotid artery stenosis per SD of sICAM-1 was 1.12 (CI 1.01–1.25, p<0.04), while for occurrence of CAC progression the OR was 1.16 (CI 1.04–1.31, p<0.01). The associations with CAC and carotid stenosis were strongest in the top 20th of the sICAM-1 distribution.
sICAM-1 concentration may be an early biomarker that indicates changes in the artery wall that accompany atherosclerosis, as well as the presence of advanced plaque in the coronary and carotid arteries. This finding holds in people with low total burden of atherosclerosis, decades prior to the development of clinical CVD.
Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may be important contributors to the development and progression of atherosclerosis. Using a stratified random sample of 2,880 participants of the Multi-Ethnic Study of Atherosclerosis we investigated the relationship of 12 ICAM1 and 17 VCAM1 SNPs and coronary artery calcium (CAC) and ICAM1 SNPs and circulating levels of soluble ICAM-1 (sICAM-1). There were no ICAM1 or VCAM1 SNPs significantly associated with CAC in any of the four race/ethnic groups. In a subset of 1,451 subjects with sICAM-1 measurements, we observed a significant association with rs5491 in all four race/ethnic groups corroborating previous research that has shown that the T-allele of rs5491 interferes with the monoclonal antibody used to measure sICAM-1 in this study. After excluding all rs5491 T-allele carriers, several ICAM1 SNPs were significantly associated with sICAM-1 levels; rs5496 in African Americans, rs5498 and rs3093030 in European Americans, and rs1799969 in Hispanics. Our results identified ICAM1 polymorphisms that were significantly associated with sICAM-1 level but not CAC, a subclinical marker of atherosclerosis.
coronary artery calcium; intercellular adhesion molecule-1 (ICAM-1); vascular adhesion molecule-1 (VCAM-1); soluble intercellular adhesion molecule-1 (sICAM-1); gene; single nucleotide polymorphism (SNP); haplotypes
Polymorphisms within the ICAM1 structural gene have been shown to influence circulating levels of soluble intercellular adhesion molecule -1 (sICAM-1) but their relation to atherosclerosis has not been clearly established. We sought to determine whether ICAM1 SNPs are associated with circulating sICAM-1 concentration, coronary artery calcium (CAC), and common and internal carotid intima medial thickness (IMT).
Methods and Results
3,550 black and white Coronary Artery Risk Development in Young Adults (CARDIA) Study subjects who participated in the year 15 and/or 20 examinations and were part of the Young Adult Longitudinal Study of Antioxidants (YALTA) ancillary study were included in this analysis. In whites, rs5498 was significantly associated with sICAM-1 (p < 0.001) and each G-allele of rs5498 was associated with 5% higher sICAM-1 concentration. In blacks, each C-allele of rs5490 was associated with 6 % higher sICAM-1 level; this SNP was in strong linkage disequilibrium with rs5491, a functional variant. Subclinical measurements of atherosclerosis in either year 15 or year 20 were not significantly related to ICAM1 SNPs.
In CARDIA, ICAM1 DNA segment variants were associated with sICAM-1 protein level including the novel finding that levels differ by the functional variant rs5491. However, ICAM1 SNPs were not strongly related to either IMT or CAC. Our findings in CARDIA suggest that ICAM1 variants are not major early contributors to subclinical atherosclerosis.
cell adhesion molecules; atherosclerosis; coronary calcium; genetics; inflammation
Endothelial cell-selective adhesion molecule (ESAM) is a junctional-type cellular adhesion molecule (CAM) that is uniquely expressed in vascular endothelium and activated platelets and mediates neutrophil and monocyte diapedesis across the endothelium. Given its role in endothelial pathobiology, we hypothesized that soluble ESAM (sESAM) would be independently associated with atherosclerosis and vascular stiffness.
Methods and Results
We measured sESAM, soluble intercellular adhesion molecule (sICAM)-1 and soluble vascular cell adhesion molecule (sVCAM)-1 in 3222 subjects participating in the Dallas Heart Study, a probability-based population sample. Coronary artery calcium (CAC) was measured by electron beam computed tomography, and abdominal aortic wall thickness (AWT), aortic plaque burden (APB), and aortic compliance (AC) by magnetic resonance imaging (MRI). Increasing levels of sESAM were associated with all major cardiovascular risk factors as well as with inflammatory markers such as monocyte chemoattractant protein-1, but only weakly correlated with sICAM-1 and sVCAM-1. In multivariate analyses, sESAM was independently associated with prevalent CAC (OR 1.2 per SD increase, 95% CI 1.1–1.3; p=0.005), AWT (p=0.035), and AC (p=0.006), but not APB (p=0.15). In contrast, no independent associations were observed between sICAM-1 or sVCAM-1 and any of the atherosclerosis phenotypes.
In this first reported clinical study of sESAM in humans, sESAM levels were independently associated with CAC, AWT, and AC, while sICAM-1 and sVCAM-1 were not. These findings support a unique role of this cellular adhesion molecule in atherosclerosis and suggest the need for further exploration of sESAM as a predictive biomarker and potential mediator of atherosclerosis.
Inflammation; Adhesion molecules; Atherosclerosis; Aortic compliance; Coronary calcium; Biomarkers
Coronary artery calcium (CAC), measured by computed tomography (CT), has strong predictive value for incident cardiovascular disease (CVD) events. The standard CAC score is the Agatston, which is weighted upward for greater calcium density. However, some data suggest increased plaque calcium density may be protective for CVD.
To determine the independent associations of CAC volume and CAC density with incident CVD events.
Design, Setting, and Participants
Multicenter, prospective observational MESA study (Multi-Ethnic Study of Atherosclerosis), conducted at 6 US field centers of 3398 men and women from 4 race/ethnicity groups; non-Hispanic white, African American, Hispanic, and Chinese. Participants were aged 45-84 years, free of known CVD at baseline, had CAC greater than 0 on their baseline CT, and were followed up through October 2010.
Main Outcomes and Measures
Incident coronary heart disease (CHD) and all CVD events
During a median of 7.6 years of follow-up, there were 175 CHD events and an additional 90 other CVD events for a total of 265 CVD events. With both lnCAC volume and CAC density scores in the same multivariable model, the lnCAC volume score showed an independent association with incident CHD, with a hazard ratio (HR) of 1.81 (95% CI, 1.47-2.23) per standard deviation (SD = 1.6) increase, absolute risk increase 6.1 per 1000 person-years, and for CVD an HR of 1.68 (95% CI, 1.42-1.98) per SD increase, absolute risk increase 7.9 per 1000 person-years. Conversely, the CAC density score showed an independent inverse association, with an HR of 0.73 (95% CI, 0.58-0.91) per SD (SD = 0.7) increase for CHD, absolute risk decrease 5.5 per 1000 person-years, and an HR of 0.71 (95% CI, 0.60-0.85) per SD increase for CVD, absolute risk decrease 8.2 per 1000 person years. Area under the receiver operating characteristic curve analyses showed significantly improved risk prediction with the addition of the density score to a model containing the volume score for both CHD and CVD. In the intermediate CVD risk group, the area under the curve for CVD increased from 0.53 (95% CI, 0.48-0.59) to 0.59 (95% CI, 0.54-0.64), P = .02.
Conclusions and Relevance
CAC volume was positively and independently associated with CHD and CVD risk. At any level of CAC volume, CAC density was inversely and significantly associated with CHD and CVD risk. The role of CAC density should be considered when evaluating current CAC scoring systems.
Even among asymptomatic people at low risk (<10%) by Framingham Risk Score (FRS), high coronary artery calcium (CAC) scores signify higher predicted risk of coronary heart disease (CHD) events. We sought to determine non-invasive factors (without radiation exposure) significantly associated with CAC in low-risk, asymptomatic persons. In a cross-sectional analysis, we studied 3046 participants from MESA at low 10-year predicted risk (FRS <10%) for CHD events. Multivariable logistic regression was used to assess the association of novel markers with presence of any CAC (CAC >0) and advanced CAC (CAC ≥ 300). CAC >0 and CAC ≥ 300 were present in 30% and 3.5% of participants, respectively. Factor VIIIc, fibrinogen and sICAM were each associated with CAC presence (P ≤ 0.02); and C-reactive protein, D-dimer and carotid intima-media thickness (CIMT) with advanced CAC (P ≤ 0.03). The base model combining traditional risk factors had excellent discrimination for advanced CAC (C-statistic, 0.808). Addition of the 2 best-fit models combining biomarkers plus/minus CIMT improved the c-statistics to 0.822 and 0.820, respectively. All 3 models calibrated well, but were similar in estimating individual risk probabilities for advanced CAC (prevalence = 9.97%, 10.63% and 10.10% in the highest quartiles of predicted probabilities versus 0.26%, 0.26% and 0.26% in the lowest quartiles, respectively). In conclusion, in low risk individuals, traditional risk factors alone predicted advanced CAC with high discrimination and calibration. Biomarker combinations +/− CIMT were also significantly associated with advanced CAC, but improvement in prediction and estimation of clinical risk were modest compared to traditional risk factors alone.
coronary calcium; biomarkers; novel markers; low-risk; risk factors
Coronary heart disease (CHD) is the major cause of death in the United States. Coronary artery calcification (CAC) scores are independent predictors of CHD. African Americans (AA) have higher rates of CHD but are less well-studied in genomic studies. We assembled the largest AA data resource currently available with measured CAC to identify associated genetic variants.
We analyzed log transformed CAC quantity (ln(CAC + 1)), for association with ~2.5 million single nucleotide polymorphisms (SNPs) and performed an inverse-variance weighted meta-analysis on results for 5,823 AA from 8 studies. Heritability was calculated using family studies. The most significant SNPs among AAs were evaluated in European Ancestry (EA) CAC data; conversely, the significance of published SNPs for CAC/CHD in EA was queried within our AA meta-analysis.
Heritability of CAC was lower in AA (~30%) than previously reported for EA (~50%). No SNP reached genome wide significance (p < 5E-08). Of 67 SNPs with p < 1E-05 in AA there was no evidence of association in EA CAC data. Four SNPs in regions previously implicated in CAC/CHD (at 9p21 and PHACTR1) in EA reached nominal significance for CAC in AA, with concordant direction. Among AA, rs16905644 (p = 4.08E-05) had the strongest association in the 9p21 region.
While we observed substantial heritability for CAC in AA, we failed to identify loci for CAC at genome-wide significant levels despite having adequate power to detect alleles with moderate to large effects. Although suggestive signals in AA were apparent at 9p21 and additional CAC and CAD EA loci, overall the data suggest that even larger samples and an ethnic specific focus will be required for GWAS discoveries for CAC in AA populations.
Atherosclerosis; Coronary artery calcium; Genetics; Meta-analysis; African-American
Short stature is associated with increased risk of coronary heart disease (CHD); although the mechanisms for this relationship are unknown, shared genetic factors have been proposed. Subclinical atherosclerosis, measured by coronary artery calcification (CAC), is associated with CHD events and represents part of the biological continuum to overt CHD. Many molecular mechanisms of CAC development are shared with bone growth. Thus, we examined whether there was evidence of shared genes (pleiotropy) between adult stature and CAC.
877 asymptomatic white adults (46% men) from 625 families in a community-based sample had computed tomography measures of CAC. Pleiotropy between height and CAC was determined using maximum-likelihood estimation implemented in SOLAR.
Adult height was significantly and inversely associated with CAC score (P=0.01). After adjusting for age, sex, and CHD risk factors, the estimated genetic correlation between height and CAC score was -0.37 and was significantly different than 0 (P=0.001) and -1 (P<0.001). The environmental correlation between height and CAC score was 0.60 and was significantly different than 0 (P=0.024).
Further studies of shared genetic factors between height and CAC may provide important insight into the complex genetic architecture of CHD, in part through increased understanding of the molecular pathways underlying the process of both normal growth and disease development. Bivariate genetic linkage analysis may provide a powerful mechanism for identifying specific genomic regions associated with both height and CAC.
Genetics; Atherosclerosis; Calcium; Imaging; Stature
The purpose of the study was to examine and compare the incidence and progression of coronary artery calcium (CAC) among persons with metabolic syndrome (MetS) and diabetes mellitus (DM), compared to those with neither condition.
MetS and DM are associated with subclinical atherosclerosis as evidenced by coronary artery calcium (CAC).
The Multiethnic Study of Atherosclerosis included 6,814 African-American, Asian, Caucasian, and Hispanic adults aged 45–84 free of cardiovascular disease at baseline. 5,662 subjects (51% female, mean age 61.0 ± 10.3 years) received baseline and follow-up (mean 2.4 years) cardiac CT scans. We compared the incidence of CAC in 2,927 subjects without CAC at baseline and progression of CAC in 2,735 subjects with CAC at baseline in those with MetS without DM (25.2%), DM without MetS (3.5%), or both DM and MetS (9.0%), compared to neither MetS nor DM (58%). Progression of CAC was also examined in relation to coronary heart disease events over an additional 4.9 years.
Relative to those with neither MetS nor DM, adjusted relative risks (95% confidence intervals) for incident CAC were 1.7 (1.4–2.0), 1.9 (1.4–2.4), and 1.8 (1.4–2.2) (all p<0.01) and absolute differences in mean progression (volume score) were 7.8 (4.0–11.6; p<0.01), 11.6 (2.7–20.5; p<0.05), and 22.6 (17.2–27.9; p<0.01) for those with MetS without DM, DM without MetS, and both DM and MetS, respectively. Similar findings were seen in analysis using Agatston calcium score. In addition, progression predicted CHD events in those with MetS without DM (adjusted hazard ratio 4.1, 95% CI=2.0–8.5, p<0.01) and DM (4.9 [1.3–18.4], p<0.05) among those in highest tertile of CAC increase vs. no increase).
Individuals with MetS and DM have a greater incidence and absolute progression of CAC compared to individuals without these conditions, with progression also predicting CHD events in those with MetS and DM.
atherosclerosis; diabetes; risk factors; calcification
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.
Adult height has been hypothesized to be inversely associated with coronary heart disease but studies have produced conflicting results. We sought to examine the relationship between adult height and the prevalence of coronary artery calcium (CAC), a direct measure of subclinical atherosclerosis and surrogate marker of CHD.
Method and Results
We evaluated the relationship between adult height and CAC in 2,703 participants from the NHLBI Family Heart Study who underwent cardiac computed tomography. We used generalized estimating equations to calculate the prevalence odds ratios for the presence of CAC (CAC>0) across sex-specific quartiles of height. The mean age of the sample was 54.8 years and 60.2% were female. There was an inverse association between adult height and CAC. After adjusting for age, race, field center, waist circumference, smoking, alcohol, physical activity, systolic blood pressure, antihypertensive medications, diabetes, diabetic medications, LDL cholesterol, HDL cholesterol, lipid-lowering medications, and income, individuals in the tallest quartile had 30% lower odds of having prevalent CAC. The odds ratios (95% CI) for the presence of CAC across consecutive sex-specific quartiles of height were 1.0 (reference), 1.15 (0.86–1.53), 0.95(0.73–1.22), and 0.70 (0.53–0.93), p for trend <0.01. There was no evidence of effect modification for the relationship between adult height and CAC by age or socioeconomic status.
The results of our study suggest an inverse, independent association between adult height and CAC.
risk factor; imaging; epidemiology
Both American and European guidelines recommend coronary artery calcification (CAC) as a tool for screening asymptomatic individuals at intermediate risk for coronary heart disease (CHD). These recommendations are based on epidemiologic studies mostly in the United States. We review (1) the use of CAC in primary prevention of CHD in the United States, (2) epidemiologic studies of CAC in asymptomatic adults outside of the United States, and (3) international epidemiologic studies of CAC. This review will not consider clinical studies of CAC among patients or symptomatic individuals. US studies have shown that CAC is a strong independent predictor of CHD in both sexes among middle-aged and old age groups, various ethnic groups, and individuals with and without diabetes and that CAC plays an important role in reclassifying individuals from intermediate to high risk. Studies in Europe support these conclusions. The Electron-Beam Tomography, Risk Factor Assessment Among Japanese and US Men in the Post-World-War-II birth cohort (ERA JUMP) Study is the first international study to compare subclinical atherosclerosis, including CAC among Japanese, Japanese Americans, Koreans, and whites. It showed that as compared with whites, Japanese had lower levels of atherosclerosis, whereas Japanese Americans had similar or higher levels. CAC is being increasingly used as a screening tool for asymptomatic individuals in Europe and the United States. CAC is a powerful research tool, because it enables us to describe differences in atherosclerotic burden across populations. Such research could identify factors responsible for differences among populations, which may improve CHD prevention.
coronary artery calcification; primary prevention; coronary calcium score; EBCT; MDCT
Conflicting evidence exists regarding whether obesity is independently associated with coronary artery calcium (CAC), a measure of coronary atherosclerosis. We examined an independent association of obesity with prevalent CAC among samples of multi-ethnic groups whose background populations have varying levels of obesity and coronary heart disease (CHD).
Methods and results
We analysed a population-based sample of 1212 men, aged 40–49 years free of clinical cardiovascular disease recruited in 2002–06; 310 Japanese in Japan (JJ), 294 Koreans in South Korea (KN), 300 Japanese Americans (JA), and 308 Whites in the USA (UW). We defined prevalent CAC as an Agatston score of ≥10. Prevalent CAC was calculated by tertile of the body mass index (BMI) in each ethnic group and was plotted against the corresponding median of tertile BMI. Additionally, logistic regression was conducted to examine whether an association of the BMI was independent of conventional risk factors. The median BMI and crude prevalence of CAC for JJ, KN, JA, and UW were 23.4, 24.4, 27.4, and 27.1 (kg/m2); 12, 11, 32, and 26 (%), respectively. Despite the absolute difference in levels of BMI and CAC across groups, higher BMI was generally associated with higher prevalent CAC in each group. After adjusting for age, smoking, alcohol, hypertension, lipids, and diabetes mellitus, the BMI was positively and independently associated with prevalent CAC in JJ, KN, UW, but not in JA.
In this multi-ethnic study, obesity was independently associated with subclinical stage of coronary atherosclerosis among men aged 40–49 years regardless of the BMI level.
Coronary artery calcium; Obesity; Body mass index; Multi-ethnic; Men; Risk factors
Soluble intercellular adhesion molecule-1 (sICAM-1) is a transmembrane protein involved in the migration and adhesion of leukocytes to the vascular endothelium. While some studies indicate that elevated baseline sICAM-1 levels predict cardiovascular events, most of these studies were done in men; moreover, uncertainty exists regarding whether sICAM-1 levels predict vascular events consistent with acute thrombosis versus atherosclerotic disease progression.
Methods and Results
In this prospective evaluation of 23, 984 apparently healthy women, we measured sICAM-1 levels and followed participants for the development of cardiovascular (CVD) endpoints typically associated with atherosclerotic disease progression with resultant vessel narrowing (percutaneous transluminal angioplasty and coronary artery bypass grafting) and endpoints typically associated with vascular thrombosis and vessel occlusion (myocardial infarction, ischemic stroke and death from a coronary cause). During a mean follow-up of 10 years, there were 741 events. For vascular events indicative of coronary atherosclerotic disease progression with luminal narrowing, Cox-proportional hazards models revealed an increase in vascular event rates from the lowest to highest quintile of baseline sICAM-1 after adjustment for CVD risk factors [Hazard Ratios (HR) 1.0, 1.4, 1.1, 1.6, 1.6, p trend=0.008]. By contrast, for endpoints reflective of acute vessel thrombosis, we found no association with sICAM-1 levels [HR for myocardial infarction (MI): 1.0, 1.2, 0.9, 1.2, 1.0, p trend=0.7; HR for stroke (CVA): 1.0, 0.9, 1.0, 1.0, 1.1, p trend = 0.6; HR for cardiovascular death: 1.0, 0.9, 0.7, 0.7, 0.8, p trend =0.7] except among smokers (RR= 1.0, 1.4, 2.8, 3.8, 3.7, p=0.007).
Among women without a history of cardiovascular disease, sICAM-1 levels are predictive of CVD events that reflect coronary atherosclerotic disease progression and vessel narrowing, but not those events associated with acute thrombosis/vessel occlusion.
Cellular adhesion molecule; Cardiovascular disease; Women
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 identify loci for coronary artery calcification (CAC) in patients with chronic kidney disease (CKD).
CKD is associated with increased CAC and subsequent coronary heart disease (CHD) but the mechanisms remain poorly defined. Genetic studies of CAC in CKD may provide a useful strategy for identifying novel pathways in CHD.
We performed a candidate gene study (~2,100 genes; ~50,000 SNPs) of CAC within the Chronic Renal Insufficiency Cohort (CRIC) Study (n=1,509; 57% European, 43% African ancestry). SNPs with preliminary evidence of association with CAC in CRIC were examined for association with CAC in PennCAC (n=2,560) and Amish Family Calcification Study (AFCS; n=784) samples. SNPs with suggestive replication were further analyzed for association with myocardial infarction (MI) in the Pakistan Risk of Myocardial Infarction study (PROMIS) (n=14,885).
Of 268 SNPs reaching P <5×10−4 for CAC in CRIC, 28 SNPs in 23 loci had nominal support (P <0.05 and in same direction) for CAC in PennCAC or AFCS. Besides chr9p21 and COL4A1, known loci for CHD, these included SNPs having reported GWAS association with hypertension (e.g., ATP2B1). In PROMIS, four of the 23 suggestive CAC loci (chr9p21, COL4A1, ATP2B1 and ABCA4) had significant associations with MI consistent with their direction of effect on CAC.
We identified several loci associated with CAC in CKD that also relate to MI in a general population sample. CKD imparts a high risk of CHD and may provide a useful setting for discovery of novel CHD genes and pathways.
Coronary artery calcification (CAC); chronic kidney disease (CKD); Chronic Renal Insufficiency Cohort Study (CRIC); myocardial infarction (MI); risk factors; candidate genes; single nucleotide polymorphisms (SNPs)
The JUPITER trial demonstrated that some patients with LDL-C <130 mg/dL and hsCRP ≥2 mg/L benefit from rosuvastatin, although absolute event rates were low. We sought to determine whether coronary artery calcium (CAC) may further risk stratify a JUPITER-eligible population, and to compare hsCRP vs. CAC for risk prediction in otherwise JUPITER-eligible participants.
A total of 950 MESA participants met all JUPITER entry criteria. We compared CHD and CVD event rates and multivariable-adjusted hazard ratios after stratifying by both presence and burden of CAC (0, 1–100, >100). We also calculated 5-year number needed to treat (NNT5) by applying the benefit observed in JUPITER to the observed event rates within each CAC strata.
Median follow-up was 5.8 years. Approximately 47% of the MESA JUPITER population had CAC=0, and CHD event rates in this group were <1 per 1000 person-years. Over 2/3 of all CHD events occurred in the 25% of participants with CAC >100 (20.2 per 1000 person-years). For CHD, the predicted NNT5 for CAC 0, 1–100, and >100 was 549, 94, and 24 respectively. For CVD, the NNT5 was 124, 54, and 19. Amongst otherwise JUPITER-eligible patients, presence of CAC was associated with 4.3-fold increased CHD (95% CI 2.0 – 9.3) and 2.6-fold increased CVD (95% CI 1.5–4.5), while hsCRP was not associated with either CHD or CVD after multivariable adjustment.
Within MESA, approximately half of JUPITER-eligible participants had CAC=0 and experienced an extremely low 6-year event rate. Nearly all events occurred in patients with CAC. CAC appears to further risk stratify JUPITER-eligible patients and may be used to target a subgroup of patients expected to derive the most, and the least, absolute benefit from statin treatment. Focusing treatment on the subset of individuals with measurable atherosclerosis may represent a more appropriate allocation of resources.
hsCRP; CAC; and Clinical Events
This study assessed the cross-sectional association between coronary artery calcification (CAC) and myocardial perfusion in an asymptomatic population.
Clinical studies showed that the prevalence of stress-induced ischemia increased with CAC burden among patients with coronary heart disease (CHD). Whether an association between CAC and myocardial perfusion exists in subjects without a history of CHD remains largely unknown.
A total of 222 men and women, ages 45 to 84 years old and free of CHD diagnosis, in the Minnesota field center of the MESA (Multi-Ethnic Study of Atherosclerosis) were studied. Myocardial blood flow (MBF) was measured using magnetic resonance imaging during rest and adenosine-induced hyperemia. Perfusion reserve was calculated as the ratio of hyperemic to resting MBF. Agatston CAC score was determined from chest multidetector computed tomography.
Mean values of hyperemic MBF and perfusion reserve, but not resting MBF, were monotonically lower across increasing CAC levels. After adjusting for age and gender, odds ratios (95% confidence intervals) of reduced perfusion reserve (<2.5) for subjects with CAC scores of 0, 0.1 to 99.9, 100 to 399, and ≥400 were 1.00 (reference), 2.16 (0.96 to 4.84), 2.81 (1.04 to 7.58), and 4.99 (1.73 to 14.4), respectively. Further adjustment for other coronary risk factors did not substantially modify the association. However, the inverse association between perfusion reserve and CAC attenuated with advancing age (p for interaction < 0.05).
Coronary vasodilatory response was associated inversely with the presence and severity of CAC in asymptomatic adults. Myocardial perfusion could be impaired by or manifest the progression to subclinical coronary atherosclerosis in the absence of clinical CHD.
A cluster of metabolic abnormalities termed metabolic syndrome (MetS) is associated with vascular endothelial dysfunction and oxidative internal milieu. We examined whether the association of MetS with subclinical atherosclerosis is explained by biomarkers of endothelial damage and oxidative stress.
MESA is a population based study of 45-84 year old individuals of four US ethnicities without clinical cardiovascular disease. A random sample of 997 MESA participants had data on the following biomarkers: von Willebrand Factor, soluble intercellular adhesion molecule-1 (sICAM1), CD40 ligand, soluble thrombomodulin, E-selectin, and oxidized LDL (oxLDL). We examined whether the associations of MetS with B-mode ultrasound-defined common and internal carotid intimal medial thickness (IMT) and coronary artery calcium (CAC) measured using computerized tomography were explained by the biomarkers using multiple regression methods.
MetS was associated with higher levels of each of the biomarkers (p<0.001, CD40L suggestive association p=0.004), with greater IMT (p<0.001), and with greater extent of CAC in those in whom CAC was detectable (p=0.01). The association of MetS with measures of subclinical atherosclerosis remained unchanged after adjustment for the biomarkers. After adjusting for MetS, oxLDL was suggestively associated with greater prevalence of detectable CAC (p=0.005) and thicker internal carotid IMT (p=0.002), while sICAM-1was significantly associated with greater prevalence of detectable CAC (p=0.001).
The association of MetS with subclinical atherosclerosis was independent of its association with biomarkers of endothelial damage and oxidative stress, suggesting that metabolic abnormalities and oxidative endothelial damage may lead to atherosclerotic disease through distinct mechanisms.
Metabolic syndrome; biomarkers; coronary artery atherosclerosis; carotid arteries
Higher plasma concentrations of soluble adhesion molecules have been shown to be associated with increased risk of cardiovascular events. We investigated the associations of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) with the ankle-brachial index (ABI), a measure of peripheral arterial disease (PAD), in a bi-ethnic cohort of adults without known coronary heart disease or stroke.
Participants included 1102 blacks (63 y, 74% women) and 1013 non-Hispanic whites (58 y, 59% women) belonging to hypertensive sibships. Plasma concentrations of sICAM-1 and sVCAM-1 were measured using high-sensitivity immunoassays. ABI was measured using a standard protocol and PAD was defined as ABI <0.9. Generalized estimating equations (GEE) were used to assess whether sICAM-1 and sVCAM-1 were associated with ABI and with PAD, independent of conventional risk factors.
After adjustment for conventional risk factors, blacks with sICAM-1 and sVCAM-1 concentrations in the highest quartiles had lower ABI than those in the lowest quartiles (mean ABI: 1.02 vs. 0.98, P=0.007 and 1.02 vs. 0.99, P=0.003, respectively). In multivariable logistic regression analysis, sICAM-1 and sVCAM-1 concentrations in the highest quartiles were each associated with a higher odds ratio of having PAD, compared with the lowest quartiles: odds ratio (95% CI): 5.2 (1.8–15.2) and 2.2 (1.0–4.8), respectively. In contrast, in non-Hispanic whites, sICAM-1 and sVCAM-1 concentrations were not associated with ABI or with PAD.
Higher sICAM-1 and sVCAM-1 concentrations were independently associated with a lower ABI and with PAD in blacks, but not in non-Hispanic whites.
ethnicity; sICAM-1; sVCAM-1; ankle-brachial index; peripheral arterial disease; hypertension
BACKGROUND AND OBJECTIVES:
The initial step in atherosclerosis is the adhesion of leukocytes to activated endothelial cells mediated by intercellular adhesion molecule-1 (ICAM-1). This study aimed to investigate the association of K469E polymorphism of the ICAM-1 gene and soluble ICAM-1 (sICAM-1) serum level with coronary heart disease (CHD) in Egyptian subjects.
PATIENTS AND METHODS:
Using a case-control design, we studied 100 patients with CHD, including 73 patients with acute myocardial infarction (MI) and 27 with unstable angina (UA). The control group consisted of 50 healthy subjects with normal left ventricular function. All participants were genotyped for the ICAM-1 polymorphism by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Serum sICAM-1 was measured by enzyme-linked immunoassay (ELISA).
In CHD patients, the frequencies of K genotype (KK and EK) were significantly higher when compared to controls (P<.001) and were associated with an increased risk of disease development (OR=3.8, 95% CI: 1.7 to 8.5; P=.001). K genotype frequencies in patients with MI showed no significant difference when compared to patients with UA (P= .121). Serum sICAM-1 levels were comparable between CHD patients and controls (P= .37) and between MI and UA patients (P=.23). There were no significant differences in sICAM-1 levels among patients with different genotypes (P=.532). Men presented with higher sICAM-1 levels than women (P=.004).
ICAM-1 gene polymorphism in codon 469 is associated with a risk for CHD development in Egyptian subjects. Serum sICAM-1 is not influenced by this polymorphism and is not necessarily elevated in CHD.
Elevated coronary artery calcium (CAC) is a marker for increase risk of coronary heart disease (CHD). While the majority of CHD events occur among individuals with advanced CAC, CHD can also occur in individuals with little or no calcified plaque. In this study, we sought to evaluate the characteristics associated with incident CHD events in the setting of minimal (score ≤10) or absent CAC (score of zero).
Asymptomatic participants in the Multi-Ethnic Study of Atherosclerosis (MESA) (N=6,809), were followed for occurrence of all CHD events (including myocardial infarction(MI), angina, resuscitated cardiac arrest, or CHD death) and hard CHD events (MI or CHD death). Time to incident CHD was modeled using age-and gender-adjusted Cox regression.
The final study population consisted of 3,923 MESA asymptomatic participants (mean age: 58±9years,39% males) had with CAC scores of 0-10. Overall no detectable CAC was seen in 3415 individuals, whereas 508 had CAC scores of 1-10. During follow up (median 4.1 years) there were 16 incident hard events, and 28 all CHD events in individuals with absent or minimal CAC. In age, gender, race and CHD risk factors adjusted analysis, minimal CAC (1-10) was associated with an estimated 3-fold greater risk of a hard CHD event (HR: 3.23, 95% CI: 1.17-8.95), or of all CHD event (HR: 3.66, 95% CI 1.71-7.85) compared to those with CAC=0. Former smoking (HR=3.57; 1.08-11.77), current smoking (HR=4.93; 1.20-20.30), and diabetes (HR=3.09; 1.07-8.93) were significant risk factors for events in those with CAC=0.
Asymptomatic persons with absent or minimal CAC are at very low risk of future cardiovascular events. Individuals with minimal CAC (1-10) were significantly increased to three fold increased risk for incident CHD events relative to those with CAC scores of zero.
Computed Tomography; Prognosis; Coronary Artery Calcification; Atherosclerosis; Coronary Calcium Score; Cardiac Events
The coronary artery calcium (CAC) score predicts coronary heart disease (CHD) events, but methods for interpreting the score in combination with conventional CHD risk factors have not been established.
Methods and Results
We analyzed CAC scores and CHD risk factor measurements from 6757 Black, Chinese, Hispanic and white men and women aged 45–84 years in the Multi-Ethnic Study of Atherosclerosis (MESA). CAC was associated with age, sex, race-ethnicity, and all conventional CHD risk factors. Multivariable models using these factors predicted the presence of CAC (C-statistic = 0.789) and degree of elevation (16% of variation explained), and can be used to update a “pre-test” CHD risk estimate, such as the 10-year Framingham Risk Score, that is based on an individual’s conventional risk factors. In scenarios where a high CAC score is expected, a moderately elevated CAC score of 50 is reassuring (e.g., reducing risk from 10% to 6% in a healthy older white man); but when a low/zero CAC score is expected, even with identical pre-test CHD risk, the same CAC score of 50 may be alarmingly high (e.g., increasing risk from 10% to 20% in a middle-aged black woman with multiple risk factors). Both the magnitude and direction of the shift in risk varied markedly with pre-test CHD risk and with the pattern of risk factors.
Knowing what CAC score to expect for an individual patient, based on their conventional risk factors, may help clinicians decide when to order a CAC test and how to interpret the results.
coronary disease; calcium; imaging; epidemiology
To investigate the possibility that family history beyond early-onset coronary heart disease (CHD) might contribute to CHD susceptibility, we studied associations between additional family history and the coronary artery calcium score (CACS).
Associations between CACS and self-reports of CHD, stroke, and diabetes in first-degree relatives of 5,264 non-diabetic subjects were assessed using logistic and linear regression adjusting for risk factors; adjusted mean CACS estimates were determined by pooling results.
Family history of CHD alone and in combination with diabetes and/or stroke was significantly associated with a positive CACS compared to no family history with odds rations ranging from 1.7 (95% CI: 1.3, 2.3) to 1.9 (95% CI: 1.6, 2.3) and adjusted mean CACS estimates ranging from 137 (95% CI: 101, 173) to 184 (95% CI, 143, 226). Associations between family history of CHD and CACS were significant regardless of age at onset, sex, lineage, or number of relatives with CHD. The association between family history of diabetes only and CACS was also significant (OR, 1.3; 95% CI: 1.1, 1.7) with an adjusted mean CACS estimate of 122 (95% CI: 93, 151). Generally, family history of stroke had non-significant associations with CACS.
Numerous family history variables in addition to early-onset CHD are associated with subclinical atherosclerosis. Our results have implications for improving CHD risk assessment.
family history; coronary heart disease; stroke; diabetes; subclinical atherosclerosis
Both American and European guidelines recommend coronary artery calcification (CAC) as a tool for screening asymptomatic individuals at intermediate risk. These recommendations are based on epidemiological studies mostly in the United States (U.S.). We review (1) the use of CAC in primary prevention of coronary heart disease (CHD) in the U.S., (2) epidemiological studies of CAC in asymptomatic adults outside of the U.S., and (3) international epidemiological studies of CAC. This review does not consider clinical studies of CAC among patients or symptomatic individuals. Studies in the U.S. have documented that CAC is a strong independent predictor of CHD for both sexes, middle- to old-age groups, various ethnic groups, and diabetics and non-diabetics and that CAC plays an important role in reclassifying individuals at intermediate into high risk. Studies in Europe support these conclusions. The Electron-Beam Tomography, Risk factor Assessment among Japanese and U.S. men in the post-World-War-II birth cohort (ERA JUMP) Study is the first international research comparing subclinical atherosclerosis including CAC in Japanese, Japanese Americans, Koreas, and Caucasians. The study has demonstrated that Japanese had lower levels of atherosclerosis compared to Caucasians whereas Japanese Americans compared to Caucasians had similar or higher levels. CAC is being established as a screening tool for asymptomatic individuals in Europe and the U.S. CAC is a powerful research tool, enabling us to describe the difference in atherosclerotic burden across populations. Such research could elucidate factors responsible for the population difference, which may lead to prevention of CHD.