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.
high-density lipoprotein; remnant lipoproteins; single nucleotide polymorphism hormone therapy
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.
Lipoproteins; hormone therapy; coronary heart disease; angiography
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.
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.
cardiovascular disease; heart size; diabetes; risk-prediction
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.
RESEARCH DESIGN AND METHODS
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.
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.
arterial stiffness; endothelial markers; inflammatory markers; large and small artery elasticity; lung function; MESA Study
Older heart failure patients with preserved ejection fraction (HFpEF) have severely reduced exercise capacity and quality of life. Both brachial artery flow-mediated dilation (FMD) and peak exercise oxygen uptake (peak VO2) decline with normal aging. However, uncertainty remains regarding whether FMD is reduced beyond the degree associated with normal aging and if this contributes to reduced peak VO2 in elderly HFpEF patients.
Sixty-six older (70 ± 7 years) HFpEF patients and 47 healthy participants (16 young, 25 ± 3 years, and 31 older, 70 ± 6 years) were studied. Brachial artery diameter was measured before and after cuff occlusion using high-resolution ultrasound. Peak VO2 was measured using expired gas analysis during upright cycle exercise.
Peak VO2 was severely reduced in older HFpEF patients compared with age-matched healthy participants (15.2 ± 0.5 vs 19.6 ± 0.6 mL/kg/min, p < .0001), and in both groups, peak VO2 was reduced compared with young healthy controls (28.5 ± 0.8 mL/kg/min; both p < .0001). Compared with healthy young participants, brachial artery FMD (healthy young, 6.13% ± 0.53%) was significantly reduced in healthy older participants (4.0 ± 0.38; p < .0002) and in HFpEF patients (3.64% ± 0.28%; p < .0001). However, FMD was not different in HFpEF patients compared with healthy older participants (p = .86). Although brachial artery FMD was modestly related to peak VO2 in univariate analyses (r = .19; p = .048), it was not related in multivariate analyses that accounted for age, gender, and body size.
These results suggest that endothelial dysfunction may not be a significant independent contributor to the severely reduced exercise capacity in elderly HFpEF patients.
Exercise capacity; Aging; Flow-mediated dilation; Heart failure with preserved ejection fraction; Endothelial function
Prior studies indicate that a subset of patients diagnosed with ST-segment elevation myocardial infarction (STEMI) will have an initial non-diagnostic ECG during evaluation. However, the timing of diagnostic ECG changes in this group is unknown. Our primary aim was to describe the timing of ECG diagnosis of STEMI in patients whose initial ECG was non-diagnostic. Secondarily, we sought to compare the delivery of ACC/AHA guidelines-based care and in-hospital outcomes in this group compared to patients diagnosed with STEMI on initial ECG.
We analyzed data from 41,560 patients diagnosed with STEMI included in the NCDR® ACTION Registry®-GWTG™ from 01/2007 to 12/2010. We divided this study population into two groups: those diagnosed on initial ECG (N= 36,994) and those with an initial non-diagnostic ECG that were diagnosed on a follow-up ECG (N= 4,566).
In general, baseline characteristics and clinical presentations were similar between the two groups. For patients with an initial non-diagnostic ECG, 72.4% (N= 3,305)had an ECG diagnostic for STEMI within 90 minutes of their initial ECG. There did not appear to be significant differences in the administration of guidelines-recommended treatments for STEMI, in-hospital major bleeding (p 0.926), or death (p 0.475) between these groups.
In a national sample of patients diagnosed with STEMI, 11.0% had an initial non-diagnostic ECG. Of those patients, 72.4% had a follow-up diagnostic ECG within 90 minutes of their initial ECG. There did not appear to be clinically meaningful differences in guidelines-based treatment or major in-hospital outcomes between patients diagnosed with STEMI on an initial versus follow-up ECG.
QT is a risk factor for sudden cardiac death (SCD). A genome wide association study identified NOS1AP variants associated with QT, which have been replicated in predominantly Caucasian (CAU) populations. We used MESA to examine association of QT with NOS1AP variants in an ethnically diverse cohort.
Twenty-eight tagging SNPs spanning NOS1AP were genotyped in 2847 MESA participants (approximately equal numbers of CAU, African-Americans (AFA), Hispanics (HIS) and Chinese (CHN)), age 45–84 years, without cardiovascular disease. QT was measured using 12-lead ECG. Associations between QT and NOS1AP variants were evaluated using linear regression, adjusted for heart rate, age, gender, and field center stratified by ancestry, using an additive inheritance model. Ancestry informative markers (AIMs) and principal components using AIMs were used as additional covariates.
More NOS1AP SNPs were associated with QT in CAU than the other races. In CAU, each copy of rs1932933 risk allele was associated with an increase in QT (4.9msec, p= 7.20×10-7). Significant associations in CAU and HIS were located at the 5′ end, while associations in CHN were located at the 3′ end.
NOS1AP variants were associated with QT in CAU, with weaker evidence for selected variants in HIS and CHN. Location of significant SNPs varied across ancestry. We identified possible novel associations at the 3′ end of NOS1AP, where we observed significant association with QT in CHN only. Genotyping within these regions may determine functional variants affecting QT and SCD risk. Further investigations are needed across ethnically diverse population cohorts.
Genetics; Electrocardiography; Arrhythmia; Electrophysiology
Heart failure with a preserved ejection fraction (HFpEF) is the dominant form of heart failure in the older population. The primary chronic symptom in HFpEF is severe exercise intolerance, however, its pathophysiology and therapy are not well understood. We tested the hypothesis that older patients with HFpEF have increased arterial stiffness beyond that which occurs with normal aging and that this contributes to their severe exercise intolerance.
Sixty-nine patients ≥ 60 years with HFpEF and 62 healthy volunteers (24 young healthy subjects ≤ 30 years (YHC) and 38 older healthy subjects ≥ 60 years old (OHC) were examined. Carotid arterial stiffness was assessed using high-resolution ultrasound and peak exercise oxygen consumption (VO2) was measured using expired gas analysis.
Peak VO2 was severely reduced in the HFpEF patients compared to OHC (14.1±2.9 vs. 19.7±3.7 ml/kg/min; p<0.001) and in both was reduced compared to YHC subjects, (32.0±7.2 ml/kg/min; both p<0.001). In HFpEF compared to OHC, carotid arterial distensibility was reduced (0.97±0.45 vs. 1.33±0.55 × 10−3 mmHg−1, p=0.008) and Young’s elastic modulus (YEM) was increased (1320±884 vs. 925±530 kPa, p<0.02). Carotid arterial distensibility was directly (0.28; p=0.02) and YEM was inversely (−0.32; p=0.01) related with peak VO2.
Carotid arterial distensibility is decreased in HFpEF beyond the changes due to normal aging and is related to peak VO2. This supports the hypothesis that increased arterial stiffness contributes to exercise intolerance in HFpEF and is a potential therapeutic target.
Aging; heart failure with preserved ejection fraction; arterial stiffness; exercise capacity
Limited data exist on the prevalence, associations and prognosis of individuals with asymptomatic left ventricular systolic dysfunction (ALVSD), especially in populations without prior clinical cardiovascular disease (CVD).
Methods and Results
Kaplan-Meier and Cox proportional hazard analyses were used to assess the association between ALVSD, defined as left ventricular ejection fraction less than 50%, and adjudicated incident congestive heart failure (CHF), all-cause mortality, and CVD events.
Out of 5004 participants, 112 participants had CHF, 321 had a CVD event, and 278 died after 9 years of follow-up. The overall prevalence of ALVSD was 1.7%, with a higher prevalence in African Americans (2.6%). ALVSD had worse cardiovascular risk profile and was also associated with increased risk in unadjusted and adjusted models for incident CHF [HR (95%): 12.0(7.04 – 20.3), p<0.0001 and 8.69(4.89 – 15.45), p<0.001 respectively], CVD [HR (95%):3.32(1.98 -5.58), p<0.001 and 2.21(1.30 – 3.73), p=0.003 respectively] and all-cause mortality [HR(95%):3.47(2.03 – 5.94), p<0.0001 and 2.00(1.13-3.54), p=0.017 respectively]. A 10% decrement in LVEF at baseline was associated with increase in risk in unadjusted and adjusted models for clinical CHF [HR (95%CI): 2.17(1.82 -2.63), p<0.0001 and 2.13(1.73 - 2.51), p<0.001 respectively] and all-cause mortality [HR (95%CI): 1.22(1.05 – 1.41), p=0.009 and 1.17(1.00 – 1.36), p=0.047 respectively]. Among the subset of participants with ALVSD, LVMI was particularly informative about risk for incident CHF (c- index = 0.74).
ALVSD is uncommon in individuals without prior clinical CVD, but is associated with high risk for CHF, CVD, and all-cause mortality. LVMI had good discrimination for incident CHF in MESA participants with ALVSD.
heart failure; death; cardiovascular diseases; magnetic resonance imaging; population
This study evaluated the association of long- and short-term air pollutant exposures with flow-mediated dilation (FMD) and baseline arterial diameter (BAD) of the brachial artery using ultrasound in a large multicity cohort.
Exposures to ambient air pollution, especially long-term exposure to particulate matter <2.5 μm in aerodynamic diameter (PM2.5), are linked with cardiovascular mortality. Short-term exposure to PM2.5 has been associated with decreased FMD and vasoconstriction, suggesting that adverse effects of PM2.5 may involve endothelial dysfunction. However, long-term effects of PM2.5 on endothelial dysfunction have not been investigated.
FMD and BAD were measured by brachial artery ultrasound at the initial examination of the Multi-Ethnic Study of Atherosclerosis. Long-term PM2.5 concentrations were estimated for the year 2000 at each participant’s residence (n = 3,040) using a spatio-temporal model informed by cohort-specific monitoring. Short-term PM2.5 concentrations were based on daily central-site monitoring in each of the 6 cities.
An interquartile increase in long-term PM2.5 concentration (3 μg/m3) was associated with a 0.3% decrease in FMD (95% confidence interval [CI] of difference: −0.6 to −0.03; p = 0.03), adjusting for demographic characteristics, traditional risk factors, sonographers, and 1/BAD. Women, nonsmokers, younger participants, and those with hypertension seemed to show a greater association of PM2.5 with FMD. FMD was not significantly associated with short-term variation in PM2.5 (−0.1% per 12 μg/m3 daily increase [95% CI: −0.2 to 0.04] on the day before examination).
Long-term PM2.5 exposure was significantly associated with decreased endothelial function according to brachial ultrasound results. These findings may elucidate an important pathway linking air pollution and cardiovascular mortality.
air pollution; atherosclerosis; cardiovascular mortality; endothelial function; flow-mediated dilation; traffic
Cardiovascular disease is the number one killer of women. Identifying women at risk of cardiovascular disease has tremendous public health importance. Early menopause is associated with increased cardiovascular disease events in some predominantly white populations, but not consistently. Our objective was to determine if a self-reported early menopause (menopause at an age <46) identifies women as at risk for future coronary heart disease or stroke.
The study population came from the Multi-Ethnic Study of Atherosclerosis, a longitudinal, ethnically diverse cohort study of US men and women aged 45 to 84 years enrolled in 2000–2002 and followed up until 2008. The association between a personal history of early menopause (either natural menopause or surgical removal of ovaries at an age <46) and future coronary heart disease and stroke was assessed in 2509 women (ages 45–84, 987 White, 331 Chinese, 641 Black, 550 Hispanic) from the Multi-Ethnic Study Atherosclerosis, who were free of cardiovascular disease at baseline.
693/2509 (28%) of women reported either surgical or natural early menopause. In survival curves, women with early menopause had worse coronary heart disease and stroke-free survival (log rank p=<0.008 and 0.0158). In models adjusted for age, race/ethnicity, Multi-Ethnic Study Atherosclerosis site and traditional cardiovascular disease risk factors, this risk for coronary heart disease and stroke remained (HR 2.08, 95% CI 1.17, 3.70 and 2.19, 95% CI 1.11, 4.32, respectively).
Early menopause is positively associated with coronary heart disease and stroke in a multiethnic cohort, independent of traditional cardiovascular disease risk factors.
Early Menopause; Coronary Heart Disease; Stroke
AHA Scientific Statements; genetics
Anaemia is associated with an increased risk for morbidity and mortality in ST-elevation myocardial infarction (STEMI) patients. While several physiological mechanisms have been proposed to explain this association, decreased receipt of guidelines-based care may also contribute. We examined the relationship between admission haemoglobin (Hgb) level, receipt of ACC/AHA guidelines-based treatments, and in-hospital outcomes among STEMI patients. We also evaluated whether administration of these treatments modified the association between anaemia and in-hospital mortality in this group.
Methods and results:
We analysed data from 92,686 patients diagnosed with STEMI included in the NCDR ACTION Registry-GWTG database from January 2007 to March 2011. Patients were stratified by initial Hgb value: 83.1% (n=77,035) were classified as non-anaemic (Hgb >13.0 g/dl for men, >12.0 g/dl for women), 11.6% (n=10,710) as mildly anaemic (11.1−13.0 g/dl for men, 11.1−12.0 g/dl for women), 4.4% (n=4059) as moderately anaemic (9.1−11.0 g/dl), and 1.0% (n=882) as severely anaemic (<9.0 g/dl). Anaemia was associated with a significantly increased prevalence of other baseline comorbidities and decreased odds of receiving several class I recommended pharmacological treatments (heparin, beta-blockers, and angiotensin-converting enzyme inhibitors, p<0.01). The overall use of reperfusion therapy (fibrinolytic therapy and/or percutaneous coronary intervention) was also lower in anaemic vs. non-anaemic patients (p<0.01). Anaemia was associated higher in-hospital mortality risk, which remained significant after adjustment for use of guidelines-recommended therapies and interventions (p<0.01).
In a national sample of STEMI patients, anaemia on presentation was associated with decreased receipt of ACC/AHA guidelines-based care and higher in-hospital mortality. However, the higher mortality rates could not be fully explained by differences in in-hospital treatment.
Anaemia; guidelines; outcomes; ST-segment myocardial infarction (STEMI); treatment
To assess the cardiovascular risk of impaired fasting glucose (IFG).
The association between IFG, incident type 2 diabetes mellitus (T2DM) and cardiovascular (CV) events remains unclear.
The Multi-Ethnic Study of Atherosclerosis (MESA) included participants aged 45–84 free of clinical CV disease at baseline (2000–2002). T2DM was defined as fasting glucose >125mg/dl or anti-diabetes medication at baseline and follow-up exams, IFG as no T2DM and fasting glucose 100–125.mg/dl. Cox proportional hazard analysis was used to assess the association between IFG and incident DM and also with incident CV events.
Of 6753 participants included in these analyses 840 (12.7%) had T2DM, 940 (13.8%) had IFG at the baseline exam. During 7.5 years of follow-up there were 418 adjudicated CV events. T2DM was associated with an increased CV incidence in the univariate [hazard ratio (HR); 2.83(2.25–3.56), p<0.0001] and multivariable models (adjusted for demographics and traditional risk factors) [HR; 1.87(1.47 – 2.37), p<0.0001] compared with subjects without T2DM (IFG + NFG). IFG was associated with increased incidence of T2DM [HR; 13.2 (95%CI 10.8–16.2), p<0.001] that remained after adjusting for demographics, highest educational level, physical activity and BMI [HR; 10.5(8.4–13.1), p<0.001] compared to NFG. IFG was associated with incident CV events in the univariate [HR; 1.64(1.26 – 2.14), p=<0.001] but not in the full multivariable model [HR; 1.16(95% CI 0.88–1.52), p=0.3] compared with NFG.
Having IFG was not independently associated with an increased short-term risk for incident CV events. These data reiterate the importance of intervention in persons with IFG to reduce their incidence of T2DM.
Impaired fasting glucose; diabetes mellitus; cardiovascular events; population
We assessed the association between sleep apnea, snoring, incident cardiovascular (CV) events and all-cause mortality in the Multi Ethnic Study of Atherosclerosis (MESA) cohort.
Out of 5338 respondents to a sleep questionnaire administered during the second MESA exam period, 208 had physician-diagnosed sleep apnea (PDSA), 1452 were habitual snorers (HS) and 3678 were neither a habitual snorer nor had PDSA (normal participants). Cox proportional hazard analysis was used to assess the associations adjusting for age, gender, race/ethnicity, smoking, diabetes mellitus, total cholesterol, HDL, triglycerides, BMI, current alcohol use, benzodiazepine use, BP medications and statin use.
Over a 7.5 year average follow-up period, 310 adjudicated CV events including MI, stroke, angina, resuscitated cardiac arrest, stroke death and CVD death and 189 deaths occurred. Compared to HS, PDSA was associated with higher incident CV rates in both univariate and multivariable models [hazard ratio (95%); 1.89(1.22–2.93), p=0.004 and 1.91(1.20 –3.04), p=0.007 respectively]. PDSA was also associated with a higher death rates compared with HS [hazard ratio (95%); 2.13(1.25 – 3.63), p=0.006 and 2.70(1.52– 4.79), p=0.007 respectively]. Compared with normal participants, PDSA had higher incident CV event rates in both univariate and multivariable models [hazard ratio (95%); 2.23[1.39–3.60], p=0.001 and 2.16[1.30–3.58], p=0.003 respectively]. Similarly, PDSA had a higher death rate compared with normal participants in both the univariate and multivariable models [hazard ratio (95%CI); 2.44(1.36 – 4.37), p=0.003 and 2.71(1.45 – 5.08), p=0.002 respectively]. Habitual snorers had similar incident CV event rates and death rates in both univariate and multivariable models compared with normal participants.
PDSA but not habitual snoring was associated with high incident CV events and all-cause mortality in a multi-ethnic population based study of adults free of clinical CV disease at baseline.
Obstructive sleep apnea; habitual snorers; cardiovascular events; mortality; population
Little is known regarding the association of scavenger receptor class B type I (SCARB1) single nucleotide polymorphisms (SNPs) and subclinical atherosclerosis (SCA), particularly in subjects of different racial/ethnic backgrounds. We examined this relationship in the Multi-Ethnic Study of Atherosclerosis (MESA).
Methods and Results
Forty-three SCARB1 tagging SNPs were genotyped. Baseline examinations included fasting lipids and SCA phenotypes (coronary artery calcium [CAC], and common and internal carotid artery thickness [CCIMT and ICIMT]). Examining SNP associations with different SCA phenotypes across multiple racial/ethnic groups with adjustment for multiple covariates, we found the C allele of SNP rs10846744 was associated with higher CCIMT in African American (P=0.03), Chinese (P=0.02), European American (P=0.05), and Hispanic participants (P=0.03), and was strongly associated in pooled analyses (P=0.0002). The results also showed that the association of this SNP with CCIMT was independent of lipids and other well-established cardiovascular risk factors. Stratifying by sex, there appeared to be a strong association of rs10846744 with CCIMT in females, but no genotype-sex interactions were observed.
Variation in SCARB1 at rs10846744 was significantly associated with CCIMT across racial/ethnic groups in MESA.
genetics; atherosclerosis; cholesterol; lipids; prospective cohort study; genetic association
In diabetes, it remains unclear whether the coronary artery calcium (CAC) score provides additional information about total mortality risk beyond traditional risk factors.
RESEARCH DESIGN AND METHODS
A total of 1,051 participants, aged 34–86 years, in the Diabetes Heart Study (DHS) were followed for 7.4 years. Subjects were separated into five groups using baseline computed tomography scans and CAC scores (0–9, 10–99, 100–299, 300–999, and ≥1,000). Logistic regression was performed adjusting for age, sex, race, smoking, and LDL cholesterol to examine the association between CAC and all-cause mortality. Areas under the curve with and without CAC were compared. Natural splines using continuous measures of CAC were fitted to estimate the relationship between observed CAC and mortality risk.
A total of 17% (178 of 1,051) of participants died during the follow-up. In multivariate analysis, the odds ratios (95% CIs) for all-cause mortality, using CAC 0–9 as the reference group, were CAC 10–99: 1.40 (0.57–3.74); CAC 100–299: 2.87 (1.17–7.77); CAC 300–999: 3.04 (1.32–7.90); and CAC ≥1,000: 6.71 (3.09–16.87). The area under the curve without CAC was 0.68 (95% CI 0.66–0.70), and the area under the curve with CAC was 0.72 (0.70–0.74) (P = 0.0001). Using splines, the estimated risk (95% CI) of mortality for a CAC of 0 was 6.7% (4.6–9.7), and the risk increased nearly linearly, plateauing at CAC ≥1,000 (20.0% [15.7–25.2]).
In diabetes, CAC was shown to be an independent predictor of mortality. Participants with CAC (0–9) were at lower risk (0.9% annual mortality). The risk of mortality increased with increasing levels of CAC, plateauing at approximately CAC ≥1,000 (2.7% annual mortality). More research is warranted to determine the potential utility of CAC scans in diabetes.
Muscadine grape seeds have high concentrations of polyphenolic compounds with antioxidant and other properties that would be expected to have favorable effects on endothelial function.
To evaluate the effect of muscadine grape seed supplementation on endothelial function and cardiovascular risk factors in subjects with increased cardiovascular risk.
In a randomized, double-blind, placebo-controlled crossover trial, 50 adults with coronary disease or ≥1 cardiac risk factor received muscadine grape seed supplementation (1300 mg daily) and placebo for 4 weeks each, with a 4-week washout. Resting brachial diameter and brachial flow-mediated dilation (FMD) and biomarkers of inflammation, lipid peroxidation, and antioxidant capacity were determined at the beginning and end of each period and compared in mixed linear models.
There was no evidence of improved FMD (% change) with muscadine grape seed (muscadine grape seed: pre 5.2% ± 0.3%, post 4.6% ± 0.3%, p = 0.06; placebo: pre 5.3% ± 0.4%, post 5.2% ± 0.4%, p = 0.82; p for muscadine grape seed vs. placebo = 0.25). However, there was a significant increase in baseline diameter (mm) with muscadine grape seed supplementation (muscadine grape seed: pre 4.05 ± 0.09, post 4.23 ± 0.10, p = 0.002; placebo: pre 4.12 ± 0.11, post 4.12 ± 0.10, p = 0.93; p for muscadine grape seed vs. placebo = 0.026). All other biomarkers were not significantly altered by muscadine grape seed supplementation.
Four weeks of muscadine grape seed supplementation in subjects with increased cardiovascular risk did not produce a statistically significant increase in brachial flow-mediated vasodilation or a significant change in other biomarkers of inflammation, lipid peroxidation, or antioxidant capacity. However, the muscadine grape seed supplement did result in a significant increase in resting brachial diameter. The clinical significance of the effect on resting diameter is not yet established. More research is warranted to fully characterize the vascular effects of this and other grape-derived nutritional supplements and to determine whether these vascular effects translate into important clinical benefits.
endothelial function; cardiovascular disease; dietary supplements; antioxidants
Background. The NCEP metabolic syndrome (MetS) is a combination of dichotomized interrelated risk factors from predominantly Caucasian populations. We propose a continuous MetS score based on principal component analysis (PCA) of the same risk factors in a multiethnic cohort and compare prediction of incident CVD events with NCEP MetS definition. Additionally, we replicated these analyses in the Health, Aging, and Body composition (Health ABC) study cohort. Methods and Results. We performed PCA of the MetS elements (waist circumference, HDL, TG, fasting blood glucose, SBP, and DBP) in 2610 Caucasian Americans, 801 Chinese Americans, 1875 African Americans, and 1494 Hispanic Americans in the multiethnic study of atherosclerosis (MESA) cohort. We selected the first principal component as a continuous MetS score (MetS-PC). Cox proportional hazards models were used to examine the association between MetS-PC and 5.5 years of CVD events (n = 377) adjusting for age, gender, race, smoking and LDL-C, overall and by ethnicity. To facilitate comparison of MetS-PC with the binary NCEP definition, a MetS-PC cut point was chosen to yield the same 37% prevalence of MetS as the NCEP definition (37%) in the MESA cohort. Hazard ratio (HR) for CVD events were estimated using the NCEP and Mets-PC-derived binary definitions. In Cox proportional models, the HR (95% CI) for CVD events for 1-SD (standard deviation) of MetS-PC was 1.71 (1.54–1.90) (P < 0.0001) overall after adjusting for potential confounders, and for each ethnicity, HRs were: Caucasian, 1.64 (1.39–1.94), Chinese, 1.39 (1.06–1.83), African, 1.67 (1.37–2.02), and Hispanic, 2.10 (1.66-2.65). Finally, when binary definitions were compared, HR for CVD events was 2.34 (1.91–2.87) for MetS-PC versus 1.79 (1.46–2.20) for NCEP MetS. In the Health ABC cohort, in a fully adjusted model, MetS-PC per 1-SD (Health ABC) remained associated with CVD events (HR = 1.21, 95%CI 1.12–1.32) overall, and for each ethnicity, Caucasian (HR = 1.24, 95%CI 1.12–1.39) and African Americans (HR = 1.16, 95%CI 1.01–1.32). Finally, when using a binary definition of MetS-PC (cut point 0.505) designed to match the NCEP definition in terms of prevalence in the Health ABC cohort (35%), the fully adjusted HR for CVD events was 1.39, 95%CI 1.17–1.64 compared with 1.46, 95%CI 1.23–1.72 using the NCEP definition. Conclusion. MetS-PC is a continuous measure of metabolic syndrome and was a better predictor of CVD events overall and in individual ethnicities. Additionally, a binary MetS-PC definition was better than the NCEP MetS definition in predicting incident CVD events in the MESA cohort, but this superiority was not evident in the Health ABC cohort.
Type 2 diabetes mellitus is associated with dyslipidemia and with an increased risk of coronary heart disease (CHD). Our objective was to compare the effects of hormone replacement therapy (HRT) on plasma lipoproteins and coronary disease progression in postmenopausal women with and without diabetes. Study subjects were participants in the Estrogen Replacement and Atherosclerosis trial, a placebo-controlled, randomized trial of HRT (conjugated equine estrogen 0.625 mg/day with or without medroxyprogesterone acetate 2.5 mg/day) in postmenopausal women with established CHD (men age 65±7 y). Plasma remnant lipoprotein levels and HDL subpopulation levels were measured at baseline and year 1. Quantitative coronary angiography was assessed at baseline and at follow-up. At baseline, remnant lipoprotein levels were significantly higher and HDL-C levels significantly lower in diabetic women than in women without diabetes. HRT lowered remnant lipoproteins and increased HDL-C and large HDL particle levels in both groups. However, during HRT, levels of these parameters were still significantly worse in diabetic women than in non-diabetic women. A significant interaction between HRT and diabetes status, with greater increases in plasma atheroprotective HDL α1 particles in non-diabetic women than in diabetic women during HRT, was observed. CHD progressed significantly more in women with diabetes than in women without diabetes. Our findings indicate that diabetes attenuates the HRT-related increase in atheroprotective HDL α1 particles. Faster progression of coronary atherosclerosis in women with diabetes could be mediated in part by a worse lipoprotein profile in these women than in women without diabetes, both before and during HRT.
Hormone replacement therapy; diabetes mellitus; lipoproteins; cholesterol; triglycerides; coronary heart disease
Introduction. Reduced kidney function, approximated by elevated cystatin C, is associated with diastolic dysfunction, heart failure, and cardiovascular mortality; however, the precise mechanism(s) that account for these relationships remains unclear. Understanding the relationship between cystatin C and subclinical left ventricular (LV) remodeling, across ethnically diverse populations, may help explain the mechanisms underlying the association of kidney dysfunction with heart failure and cardiovascular mortality. Methods. Measures of cystatin C and LV parameters were obtained from the multi-ethnic study of atherosclerosis (MESA) cohort at baseline (N = 4, 970 with complete data on cystatin C and LV parameters). LV parameters; LV end-diastolic (LVEDV) and end-systolic volumes (LVESV), LV mass (LVM), concentricity (LV mass/LV end-diastolic volume), and LV ejection fraction (LVEF) were measured using magnetic resonance imaging. Nested linear models were used to examine the relationship between higher quartiles of cystatin C and LV parameters, with and without adjustment for demographics, height, and weight, and traditional cardiovascular risk factors. Similar analyses were performed stratified by ethnicity and gender. Results. A fully adjusted model demonstrated a linear relationship between higher quartiles of cystatin C and lower LVEDV, (Mean ± SE, 128 ± 0.7, 128 ± 0.7, 126 ± 0.7, 124 ± 0.8 mL; P = 0.0001). Associations were also observed between higher quartiles of cystatin C and lower LVESV (P = 0.04) and concentricity (P = 0.0001). In contrast, no association was detected between cystatin C and LVM or LVEF. In analyses stratified by race and gender, the patterns of association between cystatin C quartiles and LV parameters were qualitatively similar to the overall association. Conclusion. Cystatin C levels were inversely associated with LVEDV and LVESV with a disproportionate decrease in LVEDV compared to LVM in a multi-ethnic population. This morphometric pattern of concentric left ventricular remodeling, may in part explain the process by which kidney dysfunction leads to diastolic dysfunction, heart failure and cardiovascular mortality.
Background. There is an association between chronic kidney disease (CKD) and metabolic syndrome (MetS). We examined the joint association of CKD and MetS with incident cardiovascular (CVD) events in the Multiethnic Study of Atherosclerosis (MESA) cohort. Methods. We analyzed 2,283 Caucasians, 363 Chinese, 1,449 African-Americans, and 1,068 Hispanics in the MESA cohort. CKD was defined by cystatin C estimated glomerular filtration rate ≤ 60 mL/min/1.73 m2 and MetS was defined by NCEP criteria. Cox proportional regression adjusting for age, ethnicity, gender, study site, education, income, smoking, alcohol use, physical activity, and total and LDL cholesterol was performed to assess the joint association of CKD and MetS with incident CVD events. Participants were divided into four groups by presence of CKD and/or MetS and compared to the group without CKD and MetS (CKD−/MetS−). Tests for additive and multiplicative interactions between CKD and MetS and prediction of incident CVD were performed. Results. During follow-up period of 5.5 years, 283 participants developed CVD. Multivariate Cox regression analysis demonstrated that CKD and MetS were independent predictors of CVD (hazard ratio, 2.02 for CKD, and 2.55 for MetS). When participants were compared to the CKD−/MetS− group, adjusted HR for the CKD+/MetS+ group was 5.56 (95% CI 3.72–8.12). There was no multiplicative interaction between CKD and MetS (P = 0.2); however, there was presence of additive interaction. The relative excess risk for additive interaction (RERI) was 2.73, P = 0.2, and the attributable portion (AP) was 0.49 (0.24–0.74). Conclusion. Our findings illustrate that the combination of CKD and MetS is a strong predictor of incident clinical cardiovascular events due to presence of additive interaction between CKD and MetS.
Interactions among genetic loci are believed to play an important role in disease risk. While many methods have been proposed for detecting such interactions, their relative performance remains largely unclear, mainly because different data sources, detection performance criteria, and experimental protocols were used in the papers introducing these methods and in subsequent studies. Moreover, there have been very few studies strictly focused on comparison of existing methods. Given the importance of detecting gene-gene and gene-environment interactions, a rigorous, comprehensive comparison of performance and limitations of available interaction detection methods is warranted.
We report a comparison of eight representative methods, of which seven were specifically designed to detect interactions among single nucleotide polymorphisms (SNPs), with the last a popular main-effect testing method used as a baseline for performance evaluation. The selected methods, multifactor dimensionality reduction (MDR), full interaction model (FIM), information gain (IG), Bayesian epistasis association mapping (BEAM), SNP harvester (SH), maximum entropy conditional probability modeling (MECPM), logistic regression with an interaction term (LRIT), and logistic regression (LR) were compared on a large number of simulated data sets, each, consistent with complex disease models, embedding multiple sets of interacting SNPs, under different interaction models. The assessment criteria included several relevant detection power measures, family-wise type I error rate, and computational complexity. There are several important results from this study. First, while some SNPs in interactions with strong effects are successfully detected, most of the methods miss many interacting SNPs at an acceptable rate of false positives. In this study, the best-performing method was MECPM. Second, the statistical significance assessment criteria, used by some of the methods to control the type I error rate, are quite conservative, thereby limiting their power and making it difficult to fairly compare them. Third, as expected, power varies for different models and as a function of penetrance, minor allele frequency, linkage disequilibrium and marginal effects. Fourth, the analytical relationships between power and these factors are derived, aiding in the interpretation of the study results. Fifth, for these methods the magnitude of the main effect influences the power of the tests. Sixth, most methods can detect some ground-truth SNPs but have modest power to detect the whole set of interacting SNPs.
This comparison study provides new insights into the strengths and limitations of current methods for detecting interacting loci. This study, along with freely available simulation tools we provide, should help support development of improved methods. The simulation tools are available at: http://code.google.com/p/simulation-tool-bmc-ms9169818735220977/downloads/list.