To determine whether long-term exposure to moderate elevations in plasma plant sterol levels increases risk for atherosclerosis.
Methods and Results
In Old Order Amish participants aged 18 to 85 years, with (n=110) and without (n=181) 1 copy of the ABCG8 G574R variant, we compared mean plasma levels of plant sterols and cholesterol precursors and carotid intima-media wall thickness. Carriers of a single 574R allele had increased plant sterol levels (eg, 35%–37% higher plasma levels of sitosterol, campesterol, and stigmasterol) and increased plant sterol/cholesterol ratios (P<0.001 for all). 574R carriers had significantly decreased levels of lathosterol and lanosterol, precursors in a pathway for endogenous cholesterol synthesis, suggesting that plant sterols may alter regulation of genes involved in cholesterol synthesis. The G574R variant was not associated with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol levels. Compared with noncarriers, 574R carriers had decreased carotid intima-media wall thickness (0.62 versus 0.66 mm; age- and sex-adjusted P=0.03). Adjustment for body weight, blood pressure, and standard lipid measures (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides) did not alter this association.
Although the G574R variant is associated with moderately elevated plant sterol levels, carriers of the 574R allele had modestly lower levels of carotid wall thickness compared with noncarriers.
ABC transporter; atherosclerosis; lipids; plant sterols; sitosterol
We assessed associations of herpes simplex virus types 1 and 2 (HSV-1 and -2), cytomegalovirus (CMV), and human herpesvirus 8 (HHV-8) infection with subclinical coronary atherosclerosis in 291 HIV-infected men in the Multicenter AIDS Cohort Study. Coronary artery calcium (CAC) was measured by non-contrast coronary CT imaging. Markers for herpesviruses infection were measured in frozen specimens collected 10-12 years prior to case identification. Multivariable logistic regression models and ordinal logistic regression models were performed. HSV-2 seropositivity was associated with coronary atherosclerosis (adjusted odds ratio [AOR] =4.12, 95% confidence interval [CI] =1.58-10.85) after adjustment for age, race/ethnicity, cardiovascular risk factors, and HIV infection related factors. Infection with a greater number of herpesviruses was associated with elevated CAC levels (AOR=1.58, 95% CI=1.06-2.36). Our findings suggest HSV-2 may be a risk factor for subclinical coronary atherosclerosis in HIV-infected men. Infection with multiple herpesviruses may contribute to the increased burden of atherosclerosis.
herpesvirus; HSV-2; atherosclerosis; HIV-1/AIDS; risk factors
Coronary heart disease (CHD) is the major cause of death in the United States. Coronary artery calcification (CAC) scores are independent predictors of CHD. African Americans (AA) have higher rates of CHD but are less well-studied in genomic studies. We assembled the largest AA data resource currently available with measured CAC to identify associated genetic variants.
We analyzed log transformed CAC quantity (ln(CAC + 1)), for association with ~2.5 million single nucleotide polymorphisms (SNPs) and performed an inverse-variance weighted meta-analysis on results for 5,823 AA from 8 studies. Heritability was calculated using family studies. The most significant SNPs among AAs were evaluated in European Ancestry (EA) CAC data; conversely, the significance of published SNPs for CAC/CHD in EA was queried within our AA meta-analysis.
Heritability of CAC was lower in AA (~30%) than previously reported for EA (~50%). No SNP reached genome wide significance (p < 5E-08). Of 67 SNPs with p < 1E-05 in AA there was no evidence of association in EA CAC data. Four SNPs in regions previously implicated in CAC/CHD (at 9p21 and PHACTR1) in EA reached nominal significance for CAC in AA, with concordant direction. Among AA, rs16905644 (p = 4.08E-05) had the strongest association in the 9p21 region.
While we observed substantial heritability for CAC in AA, we failed to identify loci for CAC at genome-wide significant levels despite having adequate power to detect alleles with moderate to large effects. Although suggestive signals in AA were apparent at 9p21 and additional CAC and CAD EA loci, overall the data suggest that even larger samples and an ethnic specific focus will be required for GWAS discoveries for CAC in AA populations.
Atherosclerosis; Coronary artery calcium; Genetics; Meta-analysis; African-American
The methodology for use of cardiac CT angiography (CTA) in low risk populations is not well defined. In order to present a reference for future studies, we present CTA methodology that is being used in an epidemiology study- the Multicenter AIDS Cohort Study (MACS).
The Multicenter AIDS Cohort Study (MACS) is an on-going multicenter prospective, observational cohort study. The MACS Cardiovascular Disease substudy plans to enroll 800 men (n= 575 HIV seropositive and n= 225 HIV seronegative) age 40-75 years for coronary atherosclerosis imaging using cardiac CTA. The protocol includes heart rate (HR) optimization with beta blockers; use of proper field of view; scan length limitation; prospective ECG-gating using the lowest beam voltage possible. All scans are evaluated for presence, extent, and composition of coronary atherosclerosis, left atrial volumes, left ventricular volume and mass and non-coronary cardiac pathology.
The first 498 participants had an average radiation dose of 2.5±1.6 milliSieverts (mSv) for the cardiac CTA study. Overall quality of scans was fair to excellent in 98.6% of studies. There were three significant adverse events- two allergic reactions to contrast and one subcutaneous contrast extravasation.
Cardiac CTA was safe and afforded a low effective radiation exposure to these asymptomatic research participants and provides valuable cardiovascular endpoints for scientific analysis. The cardiac CTA methodology described here may serve as a reference for use in future epidemiology studies aiming to assess coronary atherosclerosis and cardiac anatomy in low risk populations while minimizing radiation exposure.
CT angiography; radiation dose; epidemiological study
To evaluate the association of HIV infection and cumulative exposure to highly active antiretroviral therapy (HAART) with the presence and extent of coronary artery calcification (CAC).
A cross-sectional study of 947 male participants (332 HIV-seronegative, 84 HAART-naive and 531 HAART-experienced HIV-infected) from the Multicenter AIDS Cohort Study.
The main outcome was CAC score calculated as the geometric mean of the Agatston scores of two computed tomography replicates. Presence of CAC was defined as calcification score above 10, and extent of CAC by the score for those with CAC present. Multivariable regression was used to evaluate the association between HIV infection and HAART and presence and extent of calcification.
Increasing age was most strongly associated with both prevalence and extent of CAC for all study groups. After adjustment for age, race, family history, smoking, high-density lipoprotein-C, low-density lipoprotein-C and hypertension, HIV infection (odds ratio, 1.35; 95% confidence interval, 0.70, 2.61) and long-term HAART use (odds ratio, 1.33; 95% confidence interval, 0.87, 2.05) increased the odds for presence of CAC. In contrast, after adjustment for these covariates, the extent of CAC was lower among HAART users. Among those not taking lipid-lowering therapy, HAART usage of at least 8 years was associated with significantly reduced CAC scores (relative CAC score, 0.43; 95% confidence interval, 0.24, 0.79).
HAART use may have different effects on the presence and extent of coronary calcification. Although prevalence of calcification was marginally increased among long-term HAART users, the extent of calcification was significantly reduced among HAART users compared with HIV-seronegative controls.
Altered thyroid status exerts a major effect on the heart. Individuals with hypo- or hyperthyroidism showed various changes in electrocardiograms. However, little is known about how variations in thyroid hormone levels within the normal range affect electrical activities of the heart in the general population.
Methods and Results
We conducted a cross-sectional analysis of 5,990 men and women from the Third National Health and Nutrition Examination Survey. Serum total T4 was measured by immunoassay and TSH was measured by chemiluminescent assay. We categorized T4 and TSH into 7 groups with cut-offs at the 5th, 20th, 40th, 60th, 80th, and 95th percentiles of the weighted population distribution. Electrocardiographic parameters were measured from the standard 12-lead electrocardiogram. We found a positive linear association between serum total T4 level and heart rate in men, and a U-shape association between T4 and PR interval in men and women. TSH level was positively associated with QRS interval in men, while a U-shape association between TSH and QRS was observed in women. No clear graded association between thyroid hormones and corrected QT or JT was found, except that men in the highest category of T4 levels appeared to have longer corrected QT and JT, and men in the lowest category of T4 appeared to have shorter corrected QT and JT.
Variation in thyroid hormone levels in the general population, even within the normal range, was associated with various ECG changes.
Deficient 25-hydroxyvitamin D [25(OH)D] levels are associated with cardiovascular disease (CVD) events and mortality. Both 25(OH)D deficiency and stroke are more prevalent among blacks. We examined whether low 25(OH)D contributes to the excess risk of fatal stroke in blacks compared to whites.
Research Methods and Procedures
The Third National Health and Nutrition Examination Survey, a probability sample of US civilians, measured 25(OH)D levels and CVD risk factors between 1988–1994. Vital status through December 2006 was obtained via linkage with the National Death Index. Among white and black adults without CVD reported at baseline (n=7981), Cox regression models were fit to estimate hazard ratios (HR) for fatal stroke by 25(OH)D status and race.
During a median of 14.1 years, there were 116 and 60 fatal strokes among whites and blacks respectively. The risk of fatal stroke was greater in blacks compared to whites in models adjusted for socio-economic status and CVD risk factors, [HR 1.60 (95% CI 1.01–2.53)]. Mean baseline 25(OH)D levels were significantly lower in blacks compared to whites (19.4 vs 30.8 ng/mL, respectively). In multivariable-adjusted models, deficient 25(OH)D levels <15 ng/mL were associated with fatal stroke among whites [HR 2.13 (1.01–4.50)] but not blacks [HR 0.93 (0.49–1.80)].
Vitamin D deficiency was associated with increased risk of stroke death in whites but not blacks. Although blacks had a higher rate of fatal stroke compared to whites, the low 25(OH)D levels in blacks were unrelated to stroke incidence and therefore 25(OH)D levels did not explain this excess risk.
vitamin D; stroke; racial differences
The cholesteryl ester transport protein (CETP) plays a key role in high-density lipoprotein (HDL) metabolism. Genetic variants that alter CETP activity and concentration may cause significant alterations in HDL-cholesterol (HDL-C) concentration; however, controversies remain about whether these genetic variants are associated with atherosclerosis. We genotyped the CETP R451Q, A373P, -629C/A, Taq1B, and -2505C/A polymorphisms in a cohort of Caucasian, Chinese, African-American, and Hispanic individuals within the Multi-Ethnic Study of Atherosclerosis. Genotypes were examined in relationship to HDL-C, CETP activity, CETP concentration, and three measures of subclinical cardiovascular disease (CVD): coronary artery calcium (CAC) measured by fast CT scanning, and carotid intimal-medial thickness (IMT) and carotid artery plaque, measured by ultrasonography. Carriers of the 451Q and 373P alleles have significantly higher CETP concentration (22.4% and 19.5%, respectively; p<0.001) and activity (13.1% and 9.4%, respectively; p<0.01) and lower HDL-C (5.6% and 6.0%, respectively; p<0.05). The minor alleles of the R451Q and A373P polymorphisms are associated with the presence of CAC, even after adjusting for CVD risk factors and HDL-C (p=0.006 and p=0.01, respectively). The R451Q polymorphism is also associated with presence of carotid artery plaque (p=0.036). Neither polymorphism is associated with common or internal carotid IMT. We confirmed that the -629A, Taq1B B2, and -2505A alleles are significantly associated with lower CETP concentration (20.8%, 25.0%, and 23.7%, respectively; p<0.001) and activity (14.8%, 19.8%, and 18.4%, respectively; p<0.001) and higher HDL-C concentration (9.7%, 11.5%, and 10.4%, respectively; p<0.01). However, we did not find any associations between these non-coding polymorphisms and subclinical CVD.
CETP; CVD; HDL; MESA
Elevated low-density lipoprotein cholesterol (LDL-C) levels are a major cardiovascular disease risk factor. Genetic factors are an important determinant of LDL-C levels.
To identify single nucleotide polymorphisms associated with LDL-C and subclinical coronary atherosclerosis, we performed a genome-wide association study of LDL-C in 841 asymptomatic Amish individuals aged 20 to 80 years, with replication in a second sample of 663 Amish individuals. We also performed scanning for coronary artery calcification (CAC) in 1018 of these individuals.
From the initial genome-wide association study, a cluster of single nucleotide polymorphisms in the region of the apolipoprotein B-100 gene (APOB) was strongly associated with LDL-C levels (P < 10−68). Additional genotyping revealed the presence of R3500Q, the mutation responsible for familial defective apolipoprotein B-100, which was also strongly associated with LDL-C in the replication sample (P < 10−36). The R3500Q carrier frequency, previously reported to be 0.1% to 0.4% in white European individuals, was 12% in the combined sample of 1504 Amish participants, consistent with a founder effect. The mutation was also strongly associated with CAC in both samples (P < 10−6 in both) and accounted for 26% and 7% of the variation in LDL-C levels and CAC, respectively. Compared with noncarriers, R3500Q carriers on average had LDL-C levels 58 mg/dL higher, a 4.41-fold higher odds (95% confidence interval, 2.69–7.21) of having detectable CAC, and a 9.28-fold higher odds (2.93–29.35) of having extensive CAC (CAC score ≥400).
The R3500Q mutation in APOB is a major determinant of LDL-C levels and CAC in the Amish.
Carotid-femoral pulse wave velocity (CFPWV) is a heritable measure of aortic stiffness that is strongly associated with increased risk for major cardiovascular disease events.
Methods and Results
We conducted a meta-analysis of genome-wide association data in 9 community-based European ancestry cohorts consisting of 20,634 participants. Results were replicated in 2 additional European ancestry cohorts involving 5,306 participants. Based on a preliminary analysis of 6 cohorts, we identified a locus on chromosome 14 in the 3′-BCL11B gene desert that is associated with CFPWV (rs7152623, minor allele frequency = 0.42, beta=−0.075±0.012 SD/allele, P = 2.8 x 10−10; replication beta=−0.086±0.020 SD/allele, P = 1.4 x 10−6). Combined results for rs7152623 from 11 cohorts gave beta=−0.076±0.010 SD/allele, P=3.1x10−15. The association persisted when adjusted for mean arterial pressure (beta=−0.060±0.009 SD/allele, P = 1.0 x 10−11). Results were consistent in younger (<55 years, 6 cohorts, N=13,914, beta=−0.081±0.014 SD/allele, P = 2.3 x 10−9) and older (9 cohorts, N=12,026, beta=−0.061±0.014 SD/allele, P=9.4x10−6) participants. In separate meta-analyses, the locus was associated with increased risk for coronary artery disease (hazard ratio [HR]=1.05, confidence interval [CI]=1.02 to 1.08, P=0.0013) and heart failure (HR=1.10, CI=1.03 to 1.16, P=0.004).
Common genetic variation in a locus in the BCL11B gene desert that is thought to harbor one or more gene enhancers is associated with higher CFPWV and increased risk for cardiovascular disease. Elucidation of the role this novel locus plays in aortic stiffness may facilitate development of therapeutic interventions that limit aortic stiffening and related cardiovascular disease events.
aorta; arterial stiffness; pulse wave velocity; genetics; cardiovascular disease
Despite the recognized risk of accelerated atherosclerosis in patients with rheumatoid arthritis (RA), little is known about cardiovascular risk management in contemporary cohorts of these patients. We tested the hypotheses that major modifiable cardiovascular risk factors were more frequent and rates of treatment, detection, and control were lower in patients with RA than in non-RA controls.
The prevalence of hypertension, diabetes, elevated low-density lipoprotein (LDL) cholesterol, elevated body mass index, smoking, moderate-high 10-year cardiovascular risk and the rates of underdiagnosis, therapeutic treatment, and recommended management were compared in 197 RA patients and 274 frequency-matched control subjects, and their associations with clinical characteristics were examined.
Eighty percent of RA patients and 81% of control subjects had at least 1 modifiable traditional cardiovascular risk factor. Hypertension was more prevalent in the RA group (57%) than in controls [42%, P =0.001]. There were no statistically significant differences in the frequency of diabetes, elevated body mass index, smoking, intermediate-high 10-year coronary heart disease risk, or elevated LDL in patients with RA versus controls. Rates of newly identified diabetes, hypertension, and hyperlipidemia were similar in RA patients versus controls. Rates of therapeutic interventions were low in both groups but their use was associated with well-controlled blood pressure (OR = 4.55, 95% CI: 1.70, 12.19) and lipid levels (OR = 9.90, 95% CI: 3.30, 29.67).
Hypertension is more common in RA than in controls. Other traditional cardiovascular risk factors are highly prevalent, underdiagnosed, and poorly controlled in patients with RA, as well as controls.
rheumatoid arthritis; cardiovascular risk; epidemiology
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.
cardiac computed tomography; coronary artery calcification; coronary atherosclerosis; genome-wide association studies; myocardial infarction
Circulating adiponectin has been associated with both clinical and subclinical cardiovascular disease (CVD). Variants of the adiponectin gene (ADIPOQ) are associated with clinical CVD, but little is known about associations with subclinical CVD. We studied the association of 11 ADIPOQ SNPs with common and internal carotid intima media thickness (cIMT), presence of coronary artery calcification (CAC), and CAC scores (in those with CAC) in 2847 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Participants were Caucasian (n=712), African-American (n=712), Chinese (n=718), and Hispanic (n=705). All models were adjusted for age, sex, and field site, and stratified by race/ethnic group. African-Americans with genotypes AG/GG of rs2241767 had 36% greater (95% CI (16%, 59%), p=0.0001) CAC prevalence; they also had a larger common cIMT (p=0.0043). Also in African-Americans, genotypes AG/AA of rs1063537 were associated with a 35% (95% CI (14%, 59%), p=0.0005) greater CAC prevalence. Hispanics with the AA genotype of rs11711353 had a 37% (95% CI (14%, 66%), p=0.0011), greater CAC prevalence compared to those with the GG genotype. Additional adjustment for ancestry in African-American and Hispanic participants did not change the results. No single SNP was associated with subclinical CVD phenotypes in Chinese or Caucasian participants. There appears to be an association between ADIPOQ SNPs and subclinical CVD in African-American and Hispanics. Replication as well as assessment of other ADIPOQ SNPs appears warranted.
Objectives. Cardiovascular disease remains the major cause of death in SLE. We assessed the degree to which cardiovascular risk factors (CVRFs) and disease activity were associated with 2-year changes in measures of subclinical atherosclerosis.
Methods. One hundred and eighty-seven SLE patients participating in a placebo-controlled trial of atorvastatin underwent multi-detector CT [for coronary artery calcium (CAC)] and carotid duplex [for carotid intima–media thickness (IMT) and carotid plaque] twice, 2 years apart. During the 2 years, patients were assessed every 3 months for CVRF. Both groups were combined for analysis, as atorvastatin did not differ from placebo in preventing progression of coronary calcium. We examined the correlation between these clinical measures and progression of CAC, IMT and plaque during the follow-up period.
Results. In an analysis adjusting for age, gender and ethnicity, CAC progression was positively associated with total serum cholesterol measured over the 2-year period (P = 0.04) and smoking (P = 0.003). Carotid IMT progression was associated with systolic BP (P = 0.003), high-sensitivity CRP (hsCRP) (P = 0.013) and white blood cell (WBC) count (P = 0.029). Carotid plaque progression, defined as patients without carotid plaque at baseline with subsequent development of plaque at follow-up, was associated with systolic BP (P = 0.003), WBC count (P = 0.02), physician's global assessment (P = 0.05), blood lymphocyte count (P = 0.048), urine protein (P = 0.017) and duration of SLE (P = 0.019).
Conclusion. Our data did not provide evidence of an association between measures of SLE disease activity (SLEDAI, anti-dsDNA, anti-phospholipid and treatment) and progression of subclinical atherosclerosis. Age and hypertension were associated with the progression of carotid IMT and plaque. Age, smoking and cholesterol were associated with progression of CAC.
Systemic lupus erythematosus; Helical computed tomography; Coronary artery calcium; Carotid intima–media thickness; Carotid plaque; Inflammation; Atherosclerosis; Carotid duplex; Coronary artery disease; Statins
To explore predictors of change in measures of carotid atherosclerosis among rheumatoid arthritis (RA) patients without known cardiovascular disease (CVD) at baseline
RA patients underwent carotid ultrasonography at two timepoints, separated by an average of 3.2 ± 0.3 years. The associations of baseline and average patient characteristics with the average yearly change in mean maximal intima-medial thickness (IMT) of the common (CCA) and internal carotid arteries (ICA), and with incident or progressive plaque in the ICA/carotid bulb, were explored.
Among the 158 RA patients, maxCCA-IMT increased in 82% (median=16 μm/year; p<0.001) and maxICA-IMT increased in 70% (median=25 μm/year; p<0.001). Incident plaque was observed in 14% without baseline plaque [incidence rate=4.2/100 person-years (95% CI 1.61–6.82)]. Plaque progression was observed in 5% with baseline plaque. Among RA predictors, the adjusted average yearly change in maxCCA-IMT was significantly greater in patients with earlier RA vs. longer disease. Those prescribed TNF inhibitors at baseline had a 37% lower adjusted rate of maxCCA-IMT progression vs. non-users (14 vs. 22 μm/year; p=0.026). For maxICA-IMT, cumulative prednisone exposure was associated with progression [1.2 μm/year per gram (95% CI 0.1–2.4)] after adjustment, and was lower in patients prescribed statins concomitant with prednisone. Higher swollen joint count and higher average CRP were both associated with incident or progressive plaque, primarily in patients with elevated baseline CVD risk based on the Framingham score.
These prospective data provide evidence for inflammation as a contributor to subclinical atherosclerosis progression in RA, potentially modified favorably by TNF inhibitors and detrimentally by glucocorticoids.
Atherosclerosis; Inflammation; prediction; carotid ultrasound
Extremely abnormal prolongation of the electrocardiographic QT interval is associated with malignant ventricular arrhythmias and sudden cardiac death. However, the implications of variations in QT-interval length within normal limits for mortality in the general population are still unclear.
We performed a meta-analysis to investigate the relation of QT interval with mortality endpoints. Inverse-variance weighted random-effects models were used to summarize the relative risks across studies. Twenty-three observational studies were included.
The pooled relative risk estimates comparing the highest with the lowest categories of QT-interval length were 1.35 (95% confidence interval = 1.24–1.46) for total mortality, 1.51 (1.29–1.78) for cardiovascular mortality, 1.71 (1.36–2.15) for coronary heart disease mortality, and 1.44 (1.01–2.04) for sudden cardiac death. A 50 msec increase in QT interval was associated with a relative risk of 1.20 (1.15–1.26) for total mortality, 1.29 (1.15–1.46) for cardiovascular mortality, 1.49 (1.25–1.76) for coronary heart disease mortality, and 1.24 (0.97–1.60) for sudden cardiac death.
We found consistent associations between prolonged QT interval and increased risk of total, cardiovascular, coronary, and sudden cardiac death. QT-interval length is a determinant of mortality in the general population.
Pulmonary arterial hypertension (PAH) is a progressive disease which causes exercise limitation, heart failure, and death. We aimed to determine the safety and efficacy of aspirin and simvastatin in PAH.
Methods and Results
We performed a randomized, double-blind, placebo-controlled 2 × 2 factorial clinical trial of aspirin and simvastatin in patients with PAH receiving background therapy at four centers. A total of 92 patients with PAH were to be randomized to aspirin 81 mg or matching placebo and simvastatin 40 mg or matching placebo. The primary outcome was six-minute walk distance (6MWD) at six months. Sixty-five subjects were randomized when the trial was terminated by the DSMB after an interim analysis showed futility in reaching the primary end point for simvastatin. After adjustment for baseline 6MWD, there was no significant difference in the 6MWD at six months between aspirin (n = 32) and placebo (n = 33) [placebo-corrected difference = −0.5 m (95%CI, −28.4 – 27.4 m), p = 0.97] or between simvastatin (n = 32) and placebo (n = 33) [placebo-corrected difference = −27.6 m (95%CI, −59.6 – 4.3 m), p = 0.09]. There tended to be more major bleeding episodes with aspirin compared to placebo (4 events vs. 1 event, respectively, p = 0.17).
Neither aspirin nor simvastatin had a significant effect on the 6MWD, although patients randomized to simvastatin tended to have a lower 6MWD at six months. These results do not support the routine treatment of patients with PAH with these medications.
pulmonary hypertension; clinical trial; anti-platelet agents; endothelial dysfunction
The association between physiologic levels of sex hormones and QT-interval duration in humans was evaluated using data from 727 men enrolled in the Third National Health and Nutrition Examination Survey and 2,942 men and 1,885 postmenopausal women enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA). Testosterone, estradiol, and sex hormone-binding globulin levels were measured in serum and free testosterone was calculated from those values. QT interval was measured using a standard 12-lead electrocardiogram. In men from the Third National Health and Nutrition Survey, the multivariate adjusted differences in average QT-interval duration comparing the highest quartiles with the lowest quartiles of total testosterone and free testosterone were −8.5 ms (95% confidence interval (CI): −15.5, −1.4) and −8.0 ms (95% CI: −13.2, −2.8), respectively. The corresponding differences were −1.8 ms (95% CI: −3.8, −0.2), and −4.7 ms (95% CI: −6.7, −2.6), respectively, in men from MESA and −0.6 ms (95% CI: −3.0, 1.8) and 0.8 ms (95% CI: −1.6, 3.3), respectively, in postmenopausal women from MESA. Estradiol levels were not associated with QT-interval duration in men, but there was a marginally significant positive association in postmenopausal women. The findings suggest that testosterone levels may explain differences in QT-interval duration between men and women and could be a contributor to population variability in QT-interval duration among men.
electrocardiography; estradiol; gonadal sex hormones; testosterone
Sex differences in cardiovascular disease mortality are more pronounced among non-Hispanic whites than other racial/ethnic groups, but it is unknown whether this variation is present in the earlier subclinical stages of disease. The authors examined racial/ethnic variation in sex differences in coronary artery calcification (CAC) and carotid intimal media thickness at baseline in 2000–2002 among participants (n = 6,726) in the Multi-Ethnic Study of Atherosclerosis using binomial and linear regression. Models adjusted for risk factors in several stages: age, traditional cardiovascular disease risk factors, behavioral risk factors, psychosocial factors, and adult socioeconomic position. Women had a lower prevalence of any CAC and smaller amounts of CAC when present than men in all racial/ethnic groups. Sex differences in the prevalence of CAC were more pronounced in non-Hispanic whites than in African Americans and Chinese Americans after adjustment for traditional cardiovascular disease risk factors, and further adjustment for behavioral factors, psychosocial factors, and socioeconomic position did not modify these results (for race/sex, Pinteraction = 0.047). Similar patterns were observed for amount of CAC among adults with CAC. Racial/ethnic variation in sex differences for carotid intimal media thickness was less pronounced. In conclusion, coronary artery calcification is differentially patterned by sex across racial/ethnic groups.
calcification, physiologic; continental population groups; coronary vessels; sex; social class
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
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
Extreme prolongation or reduction of the QT interval predisposes patients to malignant ventricular arrhythmias and sudden cardiac death, but the association of variations in the QT interval within a reference range with mortality end points in the general population is unclear.
We included 7828 men and women from the Third National Health and Nutrition Examination Survey. Baseline QT interval was measured via standard 12-lead electrocardiographic readings. Mortality end points were assessed through December 31, 2006 (2291 deaths).
After an average follow-up of 13.7 years, the association between QT interval and mortality end points was U-shaped. The multivariate-adjusted hazard ratios comparing participants at or above the 95th percentile of age-, sex-, race-, and R-R interval–corrected QT interval (≥439 milliseconds) with participants in the middle quintile (401 to <410 milliseconds) were 2.03 (95% confidence interval, 1.46-2.81) for total mortality, 2.55 (1.59-4.09) for mortality due to cardiovascular disease (CVD), 1.63 (0.96-2.75) for mortality due to coronary heart disease, and 1.65 (1.16-2.35) for non-CVD mortality. The corresponding hazard ratios comparing participants with a corrected QT interval below the fifth percentile (<377 milliseconds) with those in the middle quintile were 1.39 (95% confidence interval, 1.02-1.88) for total mortality, 1.35 (0.77-2.36) for CVD mortality, 1.02 (0.44-2.38) for coronary heart disease mortality, and 1.42 (0.97-2.08) for non-CVD mortality. Increased mortality also was observed with less extreme deviations of QT-interval duration. Similar, albeit weaker, associations also were observed with Bazett-corrected QT intervals.
Shortened and prolonged QT-interval durations, even within a reference range, are associated with increased mortality risk in the general population.
Blood pressure (BP) response to the cold pressor test (CPT) has been found to predict the development of hypertension and cardiovascular disease in prospective studies. However, the determinants of BP response to the CPT, including the role of genetic factors, are largely unknown. Additionally, to our knowledge, no study has examined the genetics of BP recovery from the CPT, including whether shared genetic factors influence both reactivity and recovery. As part of the Heredity and Phenotype Intervention (HAPI) Heart Study, we administered a 2½-minute hand CPT to 835 participants from 18 extended Amish families. We estimated the heritability of BP reactivity and recovery (measured by the incremental area under the curve) and the genetic correlations between baseline, reactivity, and recovery BP phenotypes. After adjustment for relevant covariates, including baseline BP, the heritability estimates for both systolic BP (SBP) and diastolic BP (DBP) reactivity and recovery differed significantly from zero (P<0.01), with 12–25% of the total variation in BP response attributable to additive genetic effects. The genetic correlations between baseline DBP and response phenotypes were not significantly different from 0, while the genetic correlation between DBP reactivity and recovery (0.74) was significantly different from 0 and one (P<0.005). The genetic correlation between SBP reactivity and recovery was similar (0.81, P<0.05). We conclude that, independent of baseline BP, BP response to the CPT is heritable, and that both shared and unshared genetic factors influence BP reactivity and recovery, thus stressing the importance of identifying genetic variants that influence both traits.
cardiovascular reactivity; cold pressor test; blood pressure; genetics; heritability
Increased left ventricular (LV) mass and changes in LV geometry may precede hypertension onset. The authors examined the associations of LV mass and geometry, assessed by cardiac magnetic resonance imaging, with hypertension incidence in 2,567 normotensive participants enrolled in 2000–2002 in the Multi-Ethnic Study of Atherosclerosis, an ethnically diverse, population-based, US study. Over a median follow-up of 4.8 years, 745 (29%) participants developed hypertension. In a fully adjusted model including baseline blood pressure, the relative risks of incident hypertension from the lowest to highest LV mass quartile were 1.00 (referent), 1.13 (95% confidence interval (CI): 0.89, 1.43), 1.28 (95% CI: 1.00, 1.63), and 1.78 (95% CI: 1.38, 2.30) (P < 0.001 for linear trend). Higher levels of LV concentric geometry, defined by higher LV mass to end-diastolic volume quartiles, were associated with higher risk of incident hypertension in a fully adjusted model (P = 0.044 for linear trend). In a final model containing both quartiles of LV mass and LV mass/volume along with all covariates including baseline blood pressure, higher LV mass quartiles were associated with incident hypertension (P < 0.001 for linear trend), whereas higher LV mass/volume quartiles were not (P = 0.643 for linear trend). In this multiethnic cohort, alterations in LV mass preceded hypertension onset among normotensive individuals.
hypertension; hypertrophy, left ventricular; magnetic resonance imaging; risk factors
genome-wide association study; genetic epidemiology; genetics; subclinical atherosclerosis; carotid intima media thickness; cardiovascular disease; cohort study; meta-analysis; risk