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1.  The HEART Pathway Randomized Trial 
The HEART Pathway is a decision aid designed to identify emergency department patients with acute chest pain for early discharge. No randomized trials have compared the HEART Pathway with usual care.
Methods and Results
Adult emergency department patients with symptoms related to acute coronary syndrome without ST-elevation on ECG (n=282) were randomized to the HEART Pathway or usual care. In the HEART Pathway arm, emergency department providers used the HEART score, a validated decision aid, and troponin measures at 0 and 3 hours to identify patients for early discharge. Usual care was based on American College of Cardiology/American Heart Association guidelines. The primary outcome, objective cardiac testing (stress testing or angiography), and secondary outcomes, index length of stay, early discharge, and major adverse cardiac events (death, myocardial infarction, or coronary revascularization), were assessed at 30 days by phone interview and record review. Participants had a mean age of 53 years, 16% had previous myocardial infarction, and 6% (95% confidence interval, 3.6%–9.5%) had major adverse cardiac events within 30 days of randomization. Compared with usual care, use of the HEART Pathway decreased objective cardiac testing at 30 days by 12.1% (68.8% versus 56.7%; P=0.048) and length of stay by 12 hours (9.9 versus 21.9 hours; P=0.013) and increased early discharges by 21.3% (39.7% versus 18.4%; P<0.001). No patients identified for early discharge had major adverse cardiac events within 30 days.
The HEART Pathway reduces objective cardiac testing during 30 days, shortens length of stay, and increases early discharges. These important efficiency gains occurred without any patients identified for early discharge suffering MACE at 30 days.
PMCID: PMC4413911  PMID: 25737484
acute coronary syndrome; chest pain; clinical trial; decision support techniques
2.  Association of polymorphisms in genes involved in lipoprotein metabolism with plasma concentrations of remnant lipoproteins and HDL subpopulations before and after hormone therapy in postmenopausal women 
Clinical endocrinology  2009;72(2):169-175.
A high degree of inter-individual variability in plasma lipid level response to hormone therapy (HT) has been reported. Variations in the oestrogen receptor α gene (ESR1) and in genes involved in lipid metabolism may explain some of the variability in response to HT.
Postmenopausal Caucasian women (N=208) participating in a placebo-controlled randomized trial of 3.2 years of hormone therapy (HT).
Plasma triglycerides (TG), remnant lipoprotein cholesterol (RLP-C), and high-density lipoprotein cholesterol (HDL-C) levels and HDL subpopulations were assessed at baseline and at follow-up. Single nucleotide polymorphisms (SNPs) in ESR1 and in the ATP binding cassette A1 (ABCA1), cholesteryl ester transfer protein (CETP), hepatic lipase (LIPC), lipoprotein lipase (LPL), and scavenger receptor class B type I (SRB1) genes were assessed for their association with baseline plasma levels and HT-related changes in levels of RLP-C and HDL subpopulations.
Carriers of the ESR1 PvuII or IVS1-1505 variants had lower plasma TG concentrations and higher plasma HDL-C and α-1 and preα-1 HDL particle levels at baseline and showed greater increases in HDL-C, apo A-I and α-1 particle levels after HT than wild-type carriers. Carriers of the N291S and D9N variants in the LPL gene had significantly higher remnant lipoproteins and lower α-2 HDL particle levels at baseline. The CETP TaqIB SNP was a significant determinant of baseline plasma HDL-C and HDL subpopulation profile.
SNPs in ESR1, CETP and LPL had significant effects on baseline plasma levels of TG-rich and HDL subpopulations. With the exception of ESR1 SNPs, variation in genes involved in lipid metabolism has a very modest effect on lipoprotein response to HT.
PMCID: PMC2866027  PMID: 19489872
high-density lipoprotein; remnant lipoproteins; single nucleotide polymorphism hormone therapy
3.  Changes in remnant and high-density lipoproteins associated with hormone therapy and progression of coronary artery disease in postmenopausal women 
Atherosclerosis  2008;205(1):325-330.
This study examined the effect of hormone therapy (HT) on the plasma concentration of remnant lipoprotein cholesterol (RLP-C) and high density lipoprotein (HDL) subpopulations and the contribution of HT-related changes in these lipoproteins to the progression of coronary heart disease (CHD) in postmenopausal women.
Study participants were 256 women who completed the Estrogen Replacement and Atherosclerosis (ERA) trial, a placebo-controlled, randomized trial that examined the effects of 3.2 years of conjugated equine estrogen (CEE, 0.625 mg/day) or CEE (0.625 mg/day) plus medroxyprogesterone acetate (MPA, 2.5 mg/day) on post-menopausal women with established coronary atherosclerosis. Quantitative coronary angiography and plasma RLP-C and HDL subpopulations were assessed at baseline and at follow-up.
Relative to placebo, both CEE and CEE+MPA caused a significant reduction in plasma RLP-C concentrations and a significant increase in α1 and α2 HDL subpopulations. However, in the HT-treated subjects, faster progression of coronary atherosclerosis was observed in women who experienced the greatest reductions in RLP-C and in preβ1 HDL subpopulations.
Our data suggest that individual variability in RLP-C and HDL subpopulation response to HT is a predictor of CHD progression. Lipoprotein response to HT may be an indirect marker of susceptibility to other harmful effect of HT in postmenopausal women with established CHD or an indication of formation of dysfunctional lipoproteins.
PMCID: PMC2700198  PMID: 19155011
Lipoproteins; hormone therapy; coronary heart disease; angiography
4.  Contributors to Mortality in High-Risk Diabetic Patients in the Diabetes Heart Study 
Diabetes Care  2014;37(10):2798-2803.
Not all individuals with type 2 diabetes and high coronary artery calcified plaque (CAC) experience the same risk for adverse outcomes. This study examined a subset of high-risk individuals based on CAC >1,000 mg (using a total mass score) and evaluated whether differences in a range of modifiable cardiovascular disease (CVD) risk factors provided further insights into risk for mortality.
We assessed contributors to all-cause mortality among 371 European American individuals with type 2 diabetes and CAC >1,000 from the Diabetes Heart Study (DHS) after 8.2 ± 3.0 years (mean ± SD) of follow-up. Differences in known CVD risk factors, including modifiable CVD risk factors, were compared between living (n = 218) and deceased (n = 153) participants. Cox proportional hazards regression models were used to quantify risk for all-cause mortality.
Deceased participants had a longer duration of type 2 diabetes (P = 0.02) and reduced use of cholesterol-lowering medications (P = 0.004). Adjusted analyses revealed that vascular calcified plaque scores were associated with increased risk for mortality (hazard ratio 1.31–1.63; 3.89 × 10−5 < P < 0.03). Higher HbA1c, lipids, and C-reactive protein and reduced kidney function also were associated with a 1.1- to 1.5-fold increased risk for mortality (3.45 × 10−6 < P < 0.03) after adjusting for confounding factors.
Even in this high-risk group, vascular calcification and known CVD risk factors provide useful information for ongoing assessment. The use of cholesterol-lowering medication seemed to be protective for mortality.
PMCID: PMC4392938  PMID: 24989706
5.  Genome-wide Association Study for Coronary Artery Calcification with Follow-up in Myocardial Infarction 
Circulation  2011;124(25):2855-2864.
Coronary artery calcification (CAC) detected by computed tomography is a non-invasive measure of coronary atherosclerosis, that underlies most cases of myocardial infarction (MI). We aimed to identify common genetic variants associated with CAC and further investigate their associations with MI.
Methods and Results
Computed tomography was used to assess quantity of CAC. A meta-analysis of genome-wide association studies for CAC was carried out in 9,961 men and women from five independent community-based cohorts, with replication in three additional independent cohorts (n=6,032). We examined the top single nucleotide polymorphisms (SNPs) associated with CAC quantity for association with MI in multiple large genome-wide association studies of MI. Genome-wide significant associations with CAC for SNPs on chromosome 9p21 near CDKN2A and CDKN2B (top SNP: rs1333049, P=7.58×10−19) and 6p24 (top SNP: rs9349379, within the PHACTR1 gene, P=2.65×10−11) replicated for CAC and for MI. Additionally, there is evidence for concordance of SNP associations with both CAC and with MI at a number of other loci, including 3q22 (MRAS gene), 13q34 (COL4A1/COL4A2 genes), and 1p13 (SORT1 gene).
SNPs in the 9p21 and PHACTR1 gene loci were strongly associated with CAC and MI, and there are suggestive associations with both CAC and MI of SNPs in additional loci. Multiple genetic loci are associated with development of both underlying coronary atherosclerosis and clinical events.
PMCID: PMC3397173  PMID: 22144573
cardiac computed tomography; coronary artery calcification; coronary atherosclerosis; genome-wide association studies; myocardial infarction
6.  Mediation of Cardiovascular Risk Factor Effects Through Subclinical Vascular Disease: The Multi-Ethnic Study of Atherosclerosis 
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.
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
PMCID: PMC4329880  PMID: 24876350
7.  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.
PMCID: PMC4184976  PMID: 24842921
common carotid artery; arterial stiffness; carotid intima-media thickness; women; pregnancy
8.  Association of the Lipoprotein Receptor SCARB1 Common Missense Variant rs4238001 with Incident Coronary Heart Disease 
PLoS ONE  2015;10(5):e0125497.
Previous studies in mice and humans have implicated the lipoprotein receptor SCARB1 in association with atherosclerosis and lipid levels. In the current study, we sought to examine association of SCARB1 missense single nucleotide polymorphism (SNP) rs4238001 with incident coronary heart disease (CHD).
Methods and Results
Genotypes for rs4238001 were imputed for 2,319 White, 1,570 African American, and 1,292 Hispanic-American MESA participants using the 1,000 Genomes reference set. Cox proportional hazards models were used to determine association of rs4238001 with incident CHD, with adjustments for age, sex, study site, principal components of ancestry, body mass index, diabetes status, serum creatinine, lipid levels, hypertension status, education and smoking exposure. Meta-analysis across race/ethnic groups within MESA showed statistically significant association of the T allele with higher risk of CHD under a consistent and formally adjudicated definition of CHD events in this contemporary cohort study (hazard ratio [HR]=1.49, 95% CI [1.04, 2.14], P = 0.028). Analyses combining MESA with additional population-based cohorts expanded our samples in Whites (total n = 11,957 with 871 CHD events) and African Americans (total n = 5,962 with 355 CHD events) and confirmed an increased risk of CHD overall (HR of 1.19 with 95% CI [1.04, 1.37], P = 0.013), in African Americans (HR of 1.49 with 95% CI [1.07, 2.06], P = 0.019), in males (HR of 1.29 with 95% CI [1.08, 1.54], P = 4.91x10-3) and in White males (HR of 1.24 with 95% CI [1.03, 1.51], P = 0.026).
SCARB1 missense rs4238001 is statistically significantly associated with incident CHD across a large population of multiple race/ethnic groups.
PMCID: PMC4439156  PMID: 25993026
9.  Heart Rate–Corrected QT Interval Is an Independent Predictor of All-Cause and Cardiovascular Mortality in Individuals With Type 2 Diabetes: The Diabetes Heart Study 
Diabetes Care  2014;37(5):1454-1461.
Heart rate–corrected QT (QTc) interval is associated with mortality in the general population, but this association is less clear in individuals with type 2 diabetes. We assessed the association of QTc interval with all-cause and cardiovascular disease (CVD) mortality in the Diabetes Heart Study.
We studied 1,020 participants with type 2 diabetes (83% European Americans; 55% women; mean age 61.4 years) who were free of atrial fibrillation, major ventricular conduction defects, and antiarrhythmic therapy at baseline. QT duration was automatically calculated from a standard 12-lead electrocardiogram (ECG). Following American Heart Association/American College of Cardiology Foundation recommendations, a linear scale was used to correct the QT for heart rate. Using Cox regression, risk was estimated per 1-SD increase in QTc interval as well as prolonged QTc interval (>450 ms) vs. normal QTc interval for mortality.
At baseline, the mean (SD) QTc duration was 414.9 ms (18.1), and 3.0% of participants had prolonged QTc. After a median follow-up time of 8.5 years (maximum follow-up time 13.9 years), 204 participants were deceased. In adjusted multivariate models, a 1-SD increase in QTc interval was associated with an 18% higher risk for all-cause mortality (hazard ratio 1.18 [95% CI 1.03–1.36]) and 29% increased risk for CVD mortality (1.29 [1.05–1.59]). Similar results were obtained when QTc interval was used as a categorical variable (prolonged vs. normal) (all-cause mortality 1.73 [0.95–3.15]; CVD mortality 2.86 [1.35–6.08]).
Heart rate QTc interval is an independent predictor of all-cause and CVD mortality in this population with type 2 diabetes, suggesting that additional prognostic information may be available from this simple ECG measure.
PMCID: PMC4182905  PMID: 24574343
10.  Quantifying rare, deleterious variation in 12 human cytochrome P450 drug-metabolism genes in a large-scale exome dataset 
Human Molecular Genetics  2013;23(8):1957-1963.
The study of genetic influences on drug response and efficacy (‘pharmacogenetics’) has existed for over 50 years. Yet, we still lack a complete picture of how genetic variation, both common and rare, affects each individual's responses to medications. Exome sequencing is a promising alternative method for pharmacogenetic discovery as it provides information on both common and rare variation in large numbers of individuals. Using exome data from 2203 AA and 4300 Caucasian individuals through the NHLBI Exome Sequencing Project, we conducted a survey of coding variation within 12 Cytochrome P450 (CYP) genes that are collectively responsible for catalyzing nearly 75% of all known Phase I drug oxidation reactions. In addition to identifying many polymorphisms with known pharmacogenetic effects, we discovered over 730 novel nonsynonymous alleles across the 12 CYP genes of interest. These alleles include many with diverse functional effects such as premature stop codons, aberrant splicesites and mutations at conserved active site residues. Our analysis considering both novel, predicted functional alleles as well as known, actionable CYP alleles reveals that rare, deleterious variation contributes markedly to the overall burden of pharmacogenetic alleles within the populations considered, and that the contribution of rare variation to this burden is over three times greater in AA individuals as compared with Caucasians. While most of these impactful alleles are individually rare, 7.6–11.7% of individuals interrogated in the study carry at least one newly described potentially deleterious alleles in a major drug-metabolizing CYP.
PMCID: PMC3959810  PMID: 24282029
11.  Methylomics of gene expression in human monocytes 
Human Molecular Genetics  2013;22(24):5065-5074.
DNA methylation is one of several epigenetic mechanisms that contribute to the regulation of gene expression; however, the extent to which methylation of CpG dinucleotides correlates with gene expression at the genome-wide level is still largely unknown. Using purified primary monocytes from subjects in a large community-based cohort (n = 1264), we characterized methylation (>485 000 CpG sites) and mRNA expression (>48K transcripts) and carried out genome-wide association analyses of 8370 expression phenotypes. We identified 11 203 potential cis-acting CpG loci whose degree of methylation was associated with gene expression (eMS) at a false discovery rate threshold of 0.001. Most of the associations were consistent in effect size and direction of effect across sex and three ethnicities. Contrary to expectation, these eMS were not predominately enriched in promoter regions, or CpG islands, but rather in the 3′ UTR, gene bodies, CpG shores or ‘offshore’ sites, and both positive and negative correlations between methylation and expression were observed across all locations. eMS were enriched for regions predicted to be regulatory by ENCODE (Encyclopedia of DNA Elements) data in multiple cell types, particularly enhancers. One of the strongest association signals detected (P < 2.2 × 10−308) was a methylation probe (cg17005068) in the promoter/enhancer region of the glutathione S-transferase theta 1 gene (GSTT1, encoding the detoxification enzyme) with GSTT1 mRNA expression. Our study provides a detailed description of the epigenetic architecture in human monocytes and its relationship to gene expression. These data may help prioritize interrogation of biologically relevant methylation loci and provide new insights into the epigenetic basis of human health and diseases.
PMCID: PMC3836482  PMID: 23900078
12.  Prediction of mortality using a multi-bed vascular calcification score in the Diabetes Heart Study 
Vascular calcified plaque, a measure of subclinical cardiovascular disease (CVD), is unlikely to be limited to a single vascular bed in patients with multiple risk factors. Consideration of vascular calcified plaque as a global phenomenon may allow for a more accurate assessment of the CVD burden. The aim of this study was to examine the utility of a combined vascular calcified plaque score in the prediction of mortality.
Vascular calcified plaque scores from the coronary, carotid, and abdominal aortic vascular beds and a derived multi-bed score were examined for associations with all-cause and CVD-mortality in 699 European-American type 2 diabetes (T2D) affected individuals from the Diabetes Heart Study. The ability of calcified plaque to improve prediction beyond Framingham risk factors was assessed.
Over 8.4 ± 2.3 years (mean ± standard deviation) of follow-up, 156 (22.3%) participants were deceased, 74 (10.6%) from CVD causes. All calcified plaque scores were significantly associated with all-cause (HR: 1.4-1.8; p < 1x10−5) and CVD-mortality (HR: 1.5-1.9; p < 1×10−4) following adjustment for Framingham risk factors. Associations were strongest for coronary calcified plaque. Improvement in prediction of outcome beyond Framingham risk factors was greatest using coronary calcified plaque for all-cause mortality (AUC: 0.720 to 0.757, p = 0.004) and the multi-bed score for CVD mortality (AUC: 0.731 to 0.767, p = 0.008).
Although coronary calcified plaque and the multi-bed score were the strongest predictors of all-cause mortality and CVD-mortality respectively in this T2D-affected sample, carotid and abdominal aortic calcified plaque scores also significantly improved prediction of outcome beyond traditional risk factors and should not be discounted as risk stratification tools.
Electronic supplementary material
The online version of this article (doi:10.1186/s12933-014-0160-5) contains supplementary material, which is available to authorized users.
PMCID: PMC4266952  PMID: 25496604
Vascular calcified plaque; Mortality; Computed tomography; Type 2 diabetes
13.  Pharmacogenetic meta-analysis of genome-wide association studies of LDL cholesterol response to statins 
Postmus, Iris | Trompet, Stella | Deshmukh, Harshal A. | Barnes, Michael R. | Li, Xiaohui | Warren, Helen R. | Chasman, Daniel I. | Zhou, Kaixin | Arsenault, Benoit J. | Donnelly, Louise A. | Wiggins, Kerri L. | Avery, Christy L. | Griffin, Paula | Feng, QiPing | Taylor, Kent D. | Li, Guo | Evans, Daniel S. | Smith, Albert V. | de Keyser, Catherine E. | Johnson, Andrew D. | de Craen, Anton J. M. | Stott, David J. | Buckley, Brendan M. | Ford, Ian | Westendorp, Rudi G. J. | Eline Slagboom, P. | Sattar, Naveed | Munroe, Patricia B. | Sever, Peter | Poulter, Neil | Stanton, Alice | Shields, Denis C. | O’Brien, Eoin | Shaw-Hawkins, Sue | Ida Chen, Y.-D. | Nickerson, Deborah A. | Smith, Joshua D. | Pierre Dubé, Marie | Matthijs Boekholdt, S. | Kees Hovingh, G. | Kastelein, John J. P. | McKeigue, Paul M. | Betteridge, John | Neil, Andrew | Durrington, Paul N. | Doney, Alex | Carr, Fiona | Morris, Andrew | McCarthy, Mark I. | Groop, Leif | Ahlqvist, Emma | Bis, Joshua C. | Rice, Kenneth | Smith, Nicholas L. | Lumley, Thomas | Whitsel, Eric A. | Stürmer, Til | Boerwinkle, Eric | Ngwa, Julius S. | O’Donnell, Christopher J. | Vasan, Ramachandran S. | Wei, Wei-Qi | Wilke, Russell A. | Liu, Ching-Ti | Sun, Fangui | Guo, Xiuqing | Heckbert, Susan R | Post, Wendy | Sotoodehnia, Nona | Arnold, Alice M. | Stafford, Jeanette M. | Ding, Jingzhong | Herrington, David M. | Kritchevsky, Stephen B. | Eiriksdottir, Gudny | Launer, Leonore J. | Harris, Tamara B. | Chu, Audrey Y. | Giulianini, Franco | MacFadyen, Jean G. | Barratt, Bryan J. | Nyberg, Fredrik | Stricker, Bruno H. | Uitterlinden, André G. | Hofman, Albert | Rivadeneira, Fernando | Emilsson, Valur | Franco, Oscar H. | Ridker, Paul M. | Gudnason, Vilmundur | Liu, Yongmei | Denny, Joshua C. | Ballantyne, Christie M. | Rotter, Jerome I. | Adrienne Cupples, L. | Psaty, Bruce M. | Palmer, Colin N. A. | Tardif, Jean-Claude | Colhoun, Helen M. | Hitman, Graham | Krauss, Ronald M. | Wouter Jukema, J | Caulfield, Mark J.
Nature Communications  2014;5:5068.
Statins effectively lower LDL cholesterol levels in large studies and the observed interindividual response variability may be partially explained by genetic variation. Here we perform a pharmacogenetic meta-analysis of genome-wide association studies (GWAS) in studies addressing the LDL cholesterol response to statins, including up to 18,596 statin-treated subjects. We validate the most promising signals in a further 22,318 statin recipients and identify two loci, SORT1/CELSR2/PSRC1 and SLCO1B1, not previously identified in GWAS. Moreover, we confirm the previously described associations with APOE and LPA. Our findings advance the understanding of the pharmacogenetic architecture of statin response.
Statins are effectively used to prevent and manage cardiovascular disease, but patient response to these drugs is highly variable. Here, the authors identify two new genes associated with the response of LDL cholesterol to statins and advance our understanding of the genetic basis of drug response.
PMCID: PMC4220464  PMID: 25350695
14.  Comparison of Novel Risk Markers for Improvement in Cardiovascular Risk Assessment in Intermediate Risk Individuals. The Multi-Ethnic Study of Atherosclerosis 
Risk markers including coronary artery calcium (CAC), carotid intima-media thickness (CIMT), ankle-brachial Index (ABI), brachial flow-mediated dilation (FMD), high sensitivity C -reactive protein (hs-CRP) and family history (FH) of coronary heart disease (CHD) have been reported to improve on the Framingham risk score (FRS) for prediction of CHD. However, there are no direct comparisons of these markers for risk prediction in a single cohort.
We compared improvement in prediction of incident CHD/cardiovascular disease (CVD) of these 6 risk markers within intermediate risk participants (5 % < FRS < 20%) in the Multi-Ethnic Study of Atherosclerosis (MESA).
Design, Setting and Participants
Of 6814 MESA participants from 6 US field centers, 1330 were intermediate risk, without diabetes mellitus, and had complete data on all 6 markers. Recruitment spanned July 2000 to September 2002; follow-up extended through May 2011. Probability- weighted Cox proportional hazard models were used to estimate hazard ratios (HR). Area under the receiver operator characteristic curve (AUC) and net reclassification improvement (NRI) were used to compare incremental contributions of each marker when added to the FRS + race/ethnicity.
Main Outcome Measures
Incident CHD defined as MI, angina followed by revascularization, resuscitated cardiac arrest or CHD death. Incident CVD additionally included stroke or CVD death.
After median follow-up of 7.6 years (IQR 7.3 – 7.8 years), 94 CHD and 123 CVD events occurred. CAC, ABI, hs-CRP and FH were independently associated with incident CHD in multivariable analyses [HR (95%CI: 2.60(1.94-3.50), 0.79(0.66-0.95), 1.28(1.00-1.64) and 2.18(1.38-3.42) respectively]. CIMT and FMD were not associated with incident CHD in multivariable analyses [HR (95%CI) 1.17(0.95- 1.45) and 0.95(0.78 −1.14) respectively]. Although the addition of the markers individually to the FRS +race/ethnicity improved the AUC, CAC afforded the highest increment (0.623 vs. 0.784) while FMD afforded the least [0.623 vs. 0.639]. For incident CHD, the NRI with CAC was 0.659, FMD 0.024, ABI 0.036, CIMT 0.102, FH 0.160 and hs-CRP 0.079. Similar results were obtained for incident CVD.
CAC, ABI, hs-CRP and FH are independent predictors of incident CHD/CVD in intermediate risk individuals. CAC provides superior discrimination and risk reclassification compared with other risk markers.
PMCID: PMC4141475  PMID: 22910756
15.  Relation of Short-Term Heart Rate Variability to Incident Heart Failure (From the Multi-Ethnic Study of Atherosclerosis) 
The American journal of cardiology  2013;112(4):533-540.
Whether autonomic dysfunction predates the development of symptomatic heart failure (HF), or is simply a consequence of severe HF, is unknown. We hypothesized that reduced heart rate variability (HRV, a marker of abnormal autonomic function) at baseline is associated with incident HF in individuals free of clinically recognized cardiovascular disease. In the Multi- Ethnic Study of Atherosclerosis (MESA), a community-based study of subclinical cardiovascular disease in adults age 45–84 years, we measured HRV using a standard 30-second 12-lead electrocardiogram to measure the standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive differences in R-R intervals (RMSSD). During a median follow-up of 7.6 years, 95 participants developed HF (incidence rate, 2.7/1000 person-years). After adjusting for age, sex, and ethnicity, hazard ratios for incident HF by RMSSD tertile were 2.4 (95% confidence interval [CI] 1.4–4.2) for the lowest tertile and 1.7 (95% CI 1.0–3.2) for the middle tertile (highest tertile = referent group; P for trend<0.001). The inverse association between RMSSD and incident HF persisted after adjustment for additional covariates, including diabetes, systolic blood pressure, heart rate, subclinical atherosclerosis, left ventricular endsystolic volume, interim myocardial infarction, and high sensitivity C-reactive protein (P for trend=0.009). A similarly significant inverse association was also observed for SDNN. In conclusion, baseline autonomic dysfunction is risk factor for the development of HF in a multiethnic cohort. These population-based findings implicate autonomic dysfunction in the pathogenesis of HF, and decreased short-term HRV may be a novel form of Stage B (asymptomatic) HF.
PMCID: PMC3735865  PMID: 23683953
autonomic nervous system; heart rate variability; heart failure; epidemiology
16.  Effect of Endurance Exercise Training on Endothelial function and Arterial Stiffness in Older Patients with Heart Failure and Preserved Ejection Fraction: A Randomized, Controlled, Single-Blind Trial 
To evaluate the effects of endurance exercise training (ET) on endothelial dependent flow-mediated arterial dilation (FMD) and carotid artery stiffness and their potential contributions to the training-related increase in peak exercise oxygen consumption (VO2) in older patients with heart failure with preserved ejection fraction (HFPEF).
Elderly HFFEF patients have severely reduced peak VO2 which improves with ET, however the mechanisms of this improvement are unclear. FMD and arterial distensibility are critical components of the exercise response and are reduced with aging. However, it's unknown whether these improve with ET in elderly HFPEF or contribute to the training-related improvement in peak VO2.
63 HFPEF patients (70±7 years) were randomized to 16 weeks of ET (walking, arm and leg ergometry, n=32) or attention control (CT; n=31). Peak VO2, brachial artery FMD in response to cuff ischemia, carotid artery distensibility by high-resolution ultrasound, LV function, and QOL were measured at baseline and follow-up.
ET increased peak VO2 (ET: 15.8±3.3 vs. CT: 13.8±3.1 ml/kg/min, p=0.0001) and QOL. However, brachial artery FMD (ET: 3.8±3.0% vs. CT: 4.3±3.5%, p=0.88), and carotid arterial distensibility (ET: 0.97±0.56 vs. CT: 1.07±0.34 × 10-3mm × mmHg-1 p=0.65) were unchanged. Resting LV systolic and diastolic function were unchanged by ET.
In elderly HFPEF patients, 16 weeks of ET improved peak VO2 without altering endothelial function or arterial stiffness. This suggests that other mechanisms, such as enhanced skeletal muscle perfusion and / or oxygen utilization, may be responsible for the ET-mediated increase in peak VO2 in older HFPEF patients.
PMCID: PMC3740089  PMID: 23665370
Heart Failure; Preserved ejection fraction; exercise; aging
17.  Atrial Fibrillation and the Risk of Myocardial Infarction 
JAMA internal medicine  2014;174(1):107-114.
Myocardial infarction (MI) is an established risk factor for atrial fibrillation (AF). However, the extent to which AF is a risk factor for MI has not been investigated.
To examine the risk of incident MI associated with AF.
A prospective cohort of 23 928 participants residing in the continental United States and without coronary heart disease at baseline were enrolled from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort between 2003 and 2007, with follow-up through December 2009.
Expert-adjudicated total MI events (fatal and nonfatal).
Over 6.9 years of follow-up (median 4.5 years), 648 incident MI events occurred. In a sociodemographic-adjusted model, AF was associated with about 2-fold increased risk of MI (hazard ratio [HR], 1.96 [95% CI, 1.52–2.52]). This association remained significant (HR, 1.70 [95% CI, 1.26–2.30]) after further adjustment for total cholesterol, high-density lipoprotein cholesterol, smoking status, systolic blood pressure, blood pressure–lowering drugs, body mass index, diabetes, warfarin use, aspirin use, statin use, history of stroke and vascular disease, estimated glomerular filtration rate, albumin to creatinine ratio, and C-reactive protein level. In subgroup analysis, the risk of MI associated with AF was significantly higher in women (HR, 2.16 [95% CI, 1.41–3.31]) than in men (HR, 1.39 [95% CI, 0.91–2.10]) and in blacks (HR, 2.53 [95% CI, 1.67–3.86]) than in whites (HR, 1.26 [95% CI, 0.83–1.93]); for interactions, P = .03 and P = .02, respectively. On the other hand, there were no significant differences in the risk of MI associated with AF in older (≥75 years) vs younger (<75 years) participants (HR, 2.00 [95% CI, 1.16–3.35] and HR, 1.60 [95% CI, 1.11–2.30], respectively); for interaction, P = .44.
AF is independently associated with an increased risk of incident MI, especially in women and blacks. These findings add to the growing concerns of the seriousness of AF as a public health burden: in addition to being a well-known risk factor for stroke, AF is also associated with increased risk of MI.
PMCID: PMC4115282  PMID: 24190540
18.  Relationship Between Brachial Flow - Mediated Dilation and Carotid Intima- Media Thickness in an Elderly Cohort: The Cardiovascular Health Study 
Atherosclerosis  2007;197(2):840-845.
The aim of this study was to determine the relationship between brachial flow-mediated dilation (FMD) and carotid intima-media thickness (IMT) in a large multi-ethnic elderly cohort.
Brachial flow-mediated dilation (FMD) is a physiologic measure and Carotid IMT is an anatomic structural measure of subclinical atherosclerosis. Both brachial FMD and carotid IMT have been associated with cardiovascular risk factors and cardiovascular events. The relationship between brachial FMD and carotid IMT is less clear especially in older adults.
Brachial FMD, carotid IMT and traditional cardiovascular risk factors were measured in 2338 adults, age 72–98 years who were participants in the Cardiovascular Health Study. The relationship between FMD and IMT was assessed both unadjusted and also after adjusting for age, gender, race/ethnicity. BMI, HDL, LDL, systolic and diastolic blood pressure, serum creatinine, current smoking, diabetes mellitus, hormone therapy and prior CVD.
Both brachial FMD and carotid IMT correlated significantly with age, HDL levels, waist/hip ratio, serum cholesterol and number of CV risk factors. Brachial FMD was not associated with CCA IMT in this elderly cohort (Pearson partial correlation coefficient= −0.0252, p=0.222). In the adjusted linear regression model with CCA IMT as the dependent variable, brachial FMD was also not associated with CCA IMT (beta coefficient= −0.006, p=0.470)
Brachial FMD and CCA IMT are not related in population-based older adults. Brachial FMD and CCA IMT may be distinct and independent stages in the complex atherosclerotic process.
PMCID: PMC4115586  PMID: 17804000
Brachial flow-mediated dilation; carotid intima-media thickness; endothelial function; atherosclerosis; elderly
Atherosclerosis  2007;197(2):768-776.
The association of brachial flow-mediated dilation (FMD) and cardiovascular disease (CVD) status is unclear especially in older adults whose FMD is greatly diminished. We assessed the association of FMD and the presence or absence of subclinical and clinical CVD in a population based cohort of older adults.
FMD was measured in 2971 adults aged 72–98 years (mean age 78.6 years) who participated in the Cardiovascular Health Study. Multiple linear regression analysis was used to examine the association between FMD and CVD status (clinical, subclinical and free of CVD). Out of 2791 with complete data, 82.7% were Caucasians and 59% females. 743 were classified as having clinical CVD, 607 as subclinical CVD and 1441 as neither clinical CVD nor subclinical CVD (CVD free). FMD was higher in the CVD free group compared with either the clinical (3.13 ± 0.05% vs 2.93 ± 0.07%, p=0.025) or the subclinical CVD group (3.13± 0.05% vs 2.95± 0.08%, p=0.05) after adjusting for covariates. There was no significant difference between the FMD of subjects with clinical and subclinical CVD (2.93 ± 0.07% vs 2.95 ± 0.08%, p=0.84). Similar but inverted associations were observed between height adjusted brachial artery diameter (BAD) and CVD status. However, FMD and BAD had poor diagnostic accuracies for identifying older adults with subclinical CVD.
Among older adults, those with either clinical or subclinical CVD have lower FMD than CVD free subjects. BAD showed similar but inverted associations with CVD status in this cohort. FMD and BAD had poor diagnostic accuracies for identifying older adults with subclinical CVD.
PMCID: PMC4115610  PMID: 17714717
Brachial flow-mediated dilation; brachial artery diameter; cardiovascular disease; elderly
20.  Knowledge-fused differential dependency network models for detecting significant rewiring in biological networks 
BMC Systems Biology  2014;8:87.
Modeling biological networks serves as both a major goal and an effective tool of systems biology in studying mechanisms that orchestrate the activities of gene products in cells. Biological networks are context-specific and dynamic in nature. To systematically characterize the selectively activated regulatory components and mechanisms, modeling tools must be able to effectively distinguish significant rewiring from random background fluctuations. While differential networks cannot be constructed by existing knowledge alone, novel incorporation of prior knowledge into data-driven approaches can improve the robustness and biological relevance of network inference. However, the major unresolved roadblocks include: big solution space but a small sample size; highly complex networks; imperfect prior knowledge; missing significance assessment; and heuristic structural parameter learning.
To address these challenges, we formulated the inference of differential dependency networks that incorporate both conditional data and prior knowledge as a convex optimization problem, and developed an efficient learning algorithm to jointly infer the conserved biological network and the significant rewiring across different conditions. We used a novel sampling scheme to estimate the expected error rate due to “random” knowledge. Based on that scheme, we developed a strategy that fully exploits the benefit of this data-knowledge integrated approach. We demonstrated and validated the principle and performance of our method using synthetic datasets. We then applied our method to yeast cell line and breast cancer microarray data and obtained biologically plausible results. The open-source R software package and the experimental data are freely available at
Experiments on both synthetic and real data demonstrate the effectiveness of the knowledge-fused differential dependency network in revealing the statistically significant rewiring in biological networks. The method efficiently leverages data-driven evidence and existing biological knowledge while remaining robust to the false positive edges in the prior knowledge. The identified network rewiring events are supported by previous studies in the literature and also provide new mechanistic insight into the biological systems. We expect the knowledge-fused differential dependency network analysis, together with the open-source R package, to be an important and useful bioinformatics tool in biological network analyses.
PMCID: PMC4131167  PMID: 25055984
Biological networks; Probabilistic graphical models; Differential dependency network; Network rewiring; Network analysis; Systems biology; Knowledge incorporation; Convex optimization
21.  DNA Methylation in an Enhancer Region of the FADS Cluster Is Associated with FADS Activity in Human Liver 
PLoS ONE  2014;9(5):e97510.
Levels of omega-6 (n-6) and omega-3 (n-3), long chain polyunsaturated fatty acids (LcPUFAs) such as arachidonic acid (AA; 20∶4, n-6), eicosapentaenoic acid (EPA; 20∶5, n-3) and docosahexaenoic acid (DHA; 22∶6, n-3) impact a wide range of biological activities, including immune signaling, inflammation, and brain development and function. Two desaturase steps (Δ6, encoded by FADS2 and Δ5, encoded by FADS1) are rate limiting in the conversion of dietary essential 18 carbon PUFAs (18C-PUFAs) such as LA (18∶2, n-6) to AA and α-linolenic acid (ALA, 18∶3, n-3) to EPA and DHA. GWAS and candidate gene studies have consistently identified genetic variants within FADS1 and FADS2 as determinants of desaturase efficiencies and levels of LcPUFAs in circulating, cellular and breast milk lipids. Importantly, these same variants are documented determinants of important cardiovascular disease risk factors (total, LDL, and HDL cholesterol, triglycerides, CRP and proinflammatory eicosanoids). FADS1 and FADS2 lie head-to-head (5′ to 5′) in a cluster configuration on chromosome 11 (11q12.2). There is considerable linkage disequilibrium (LD) in this region, where multiple SNPs display association with LcPUFA levels. For instance, rs174537, located ∼15 kb downstream of FADS1, is associated with both FADS1 desaturase activity and with circulating AA levels (p-value for AA levels = 5.95×10−46) in humans. To determine if DNA methylation variation impacts FADS activities, we performed genome-wide allele-specific methylation (ASM) with rs174537 in 144 human liver samples. This approach identified highly significant ASM with CpG sites between FADS1 and FADS2 in a putative enhancer signature region, leading to the hypothesis that the phenotypic associations of rs174537 are likely due to methylation differences. In support of this hypothesis, methylation levels of the most significant probe were strongly associated with FADS1 and, to a lesser degree, FADS2 activities.
PMCID: PMC4026313  PMID: 24842322
22.  Relationship between genetic variants in myocardial sodium and potassium channel genes and QT interval duration in diabetics: the Diabetes Heart Study 
Genetic variants in myocardial sodium and potassium channel genes are associated with prolonged QT interval and increased risk of sudden death. It is unclear whether these genetic variants remain relevant in subjects with underlying conditions such as diabetes that are associated with prolonged QT interval.
We tested single nucleotide polymorphisms (SNPs) in five candidate genes for association with QT interval in a family-based study of subjects with type 2 diabetes mellitus (T2DM). Thirty-six previously reported SNPs were genotyped in KCNQ1, HERG, SCN5A, KCNE1, and KCNE2 in 901 European Americans from 366 families. The heart rate-corrected (QTc) durations were determined using the Marquette 12SL program. Associations between the QTc interval and the genotypes were evaluated using SOLAR adjusting for age, gender, T2DM status, and body mass index.
Within KCNQ1 there was weak evidence for association between the minor allele of IVS12+14T>C and increased QTc (p=0.02). The minor allele of rs2236609 in KCNE1 trended toward significance with longer QTc (p=0.06), while the minor allele of rs1805123 in HERG trended toward significance with shorter QTc (p=0.07). However, no statistically significant associations were observed between the remaining SNPs and QTc variation.
We found weak evidence of association between three previously-reported SNPs and QTc interval duration. While it appears as though genetic variants in previously identified candidate genes may be associated with QT duration in subjects with diabetes, the clinical implications of these associations in diabetic subjects at high risk for sudden death remains to be determined.
PMCID: PMC3650725  PMID: 19149796
QT interval; diabetes; association study; genetics; ion channels
23.  Usefulness of Biventricular Volume as a Predictor of Mortality in Patients with Diabetes Mellitus (From the Diabetes Heart Study) 
The American journal of cardiology  2013;111(8):1152-1158.
Individuals with type 2 diabetes mellitus (DM) are at increased risk of cardiovascular disease (CVD) and mortality. Beyond traditional CVD risk factors, novel measures reflecting additional aspects of disease pathophysiology, such as biventricular volume (BiVV), may be useful for risk stratification. This study examined the relationship between BiVV and risk for mortality in European Americans with type 2 DM from the Diabetes Heart Study. BiVV was calculated from 771 non-contrast computed tomography scans performed to image coronary artery calcified plaque (CAC). Relationships between BiVV and traditional CVD risk factors were examined. Cox proportional hazards regression was performed to determine risk for mortality (all-cause and CVD-mortality) associated with increasing BiVV. Area under the curve analysis was used to assess BiVV utility in risk prediction models. During 8.4 ± 2.4 years (mean ± SD) of follow-up, 23% of the sample were deceased. In unadjusted analyses, BiVV was significantly associated with increasing body mass index, height, CAC, history of hypertension and prior myocardial infarction (p<0.0001–0.012). BiVV was significantly associated with all-cause (HR: 2.45; CI: 1.06–5.67; p=0.036) and CVD-mortality (HR: 4.36; CI: 1.36–14.03; p=0.014) in models adjusted for other known CVD risk factors. Area under the curve increased from 0.76 to 0.78 (p=0.04) and 0.74 to 0.77 (p=0.02) for all-cause and CVD-mortality on inclusion of BiVV. In conclusion, in the absence of echocardiography or other noninvasive imaging modalities to assess ventricular volumes, or when such methods are contra-indicated, BiVV from computed tomography may be considered as a tool for stratification of high-risk individuals, such as those with type 2 DM.
PMCID: PMC3618594  PMID: 23351459
cardiovascular disease; heart size; diabetes; risk-prediction
24.  Coronary Calcium Score Predicts Cardiovascular Mortality in Diabetes 
Diabetes Care  2013;36(4):972-977.
In type 2 diabetes mellitus (T2DM), it remains unclear whether coronary artery calcium (CAC) provides additional information about cardiovascular disease (CVD) mortality beyond the Framingham Risk Score (FRS) factors.
A total of 1,123 T2DM participants, ages 34–86 years, in the Diabetes Heart Study followed up for an average of 7.4 years were separated using baseline computed tomography scans of CAC (0–9, 10–99, 100–299, 300–999, and ≥1,000). Logistic regression was performed to examine the association between CAC and CVD mortality adjusting for FRS. Areas under the curve (AUC) with and without CAC were compared. Net reclassification improvement (NRI) compared FRS (model 1) versus FRS+CAC (model 2) using 7.4-year CVD mortality risk categories 0% to <7%, 7% to <20%, and ≥20%.
Overall, 8% of participants died of cardiovascular causes during follow-up. In multivariate analysis, the odds ratios (95% CI) for CVD mortality using CAC 0–9 as the reference group were, CAC 10–99: 2.93 (0.74–19.55); CAC 100–299: 3.17 (0.70–22.22); CAC 300–999: 4.41(1.15–29.00); and CAC ≥1,000: 11.23 (3.24–71.00). AUC (95% CI) without CAC was 0.70 (0.67–0.73), AUC with CAC was 0.75 (0.72–0.78), and NRI was 0.13 (0.07–0.19).
In T2DM, CAC predicts CVD mortality and meaningfully reclassifies participants, suggesting clinical utility as a risk stratification tool in a population already at increased CVD risk.
PMCID: PMC3609509  PMID: 23230101
25.  Associations among Lung Function, Arterial Elasticity and Circulating Endothelial and Inflammation Markers: the Multi-Ethnic Study of Atherosclerosis 
Hypertension  2013;61(2):542-548.
A parallel physiologic pathway for elastic changes is hypothesized for declines in arterial elasticity and lung function. Endothelial dysfunction and inflammation could potentially decrease elasticity of both vasculature and lung tissue. We examined biomarkers, large (LAE) and small (SAE) arterial elasticity, and forced vital capacity (FVC) in a period cross-sectional design in the Multi-Ethnic Study of Atherosclerosis, which recruited 1,823 women and 1,803 men, age range 45–84 years, black, white, Hispanic, and Chinese, free of clinically recognized CVD. Radial artery tonometric pulse waveform registration was performed and LAE and SAE were derived from diastole. Spirometric data and markers of endothelial dysfunction and inflammation (soluble intracellular adhesion molecule-1, fibrinogen, hs-C-reactive protein, and interleukin-6) were obtained. Mean LAE was 13.7 ± 5.5 ml/mmHgx10 and SAE was 4.6 ± 2.6 ml/mmHgx100. Mean FVC was 3,192 ± 956.0 mL and FEV1 was 2,386 ± 734.5 mL. FVC was about 40 ± 5 mL higher per SD of SAE, stronger in men than women. The association was slightly weaker with LAE, with no sex interaction. After regression adjustment for demographic, anthropometric, and cardiovascular risk factors, the biomarkers tended to be related to reduced SAE and FVC, particularly in men. These biomarker associations suggest important CVD risk alterations that occur concurrently with lower arterial elasticity and lung function. The observed positive association of SAE with FVC and with FEV1 in middle-aged to older free-living people is consistent with the hypothesis of parallel physiologic pathways for elastic changes in the vasculature and in lung parenchymal tissue.
PMCID: PMC3586233  PMID: 23283358
arterial stiffness; endothelial markers; inflammatory markers; large and small artery elasticity; lung function; MESA Study

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