High-Density Lipoprotein Particle Subfractions in Heart Failure With Preserved or Reduced Ejection Fraction.

BACKGROUND: Circulating high-density lipoprotein particle (HDL-P) subfractions impact atherogenesis, inflammation, and endothelial function, all of which are implicated in the pathobiology of heart failure (HF). OBJECTIVES: The authors sought to identify key differences in plasma HDL-P subfractions between patients with HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF) to determine their prognostic utility. METHODS: Patients with HFrEF (n = 782), HFpEF (n = 1,004), and no HF (n = 4,742) were identified in the CATHGEN (Catheterization Genetics) biorepository of sequential patients undergoing cardiac catheterization. Nuclear magnetic resonance-based lipoprotein profiling was performed on frozen fasting plasma obtained at catheterization. The authors used multivariable analysis of covariance to compare high-density lipoprotein particle (HDL-P) subfractions across groups, and Cox proportional hazards modeling to determine associations between HDL-P subfractions and time to death or major adverse cardiac events. RESULTS: Mean HDL-P size was greater in HFrEF than HFpEF, both of which were greater than in no HF (all 2-way p < 0.0001). By contrast, concentrations of small HDL-P and total HDL-P were lesser in HFrEF than HFpEF, which were both lesser than no HF (all 2-way p ≤ 0.0002). In both HFrEF and HFpEF, total HDL-P and small HDL-P were inversely associated with time to adverse events. These findings persisted after adjustment for 14 clinical covariates (including high-density lipoprotein cholesterol content, coronary artery disease, and the inflammatory biomarker GlycA), and in sensitivity analyses featuring alternate left ventricular ejection fraction definitions, or stricter inclusion criteria with diastolic dysfunction or left ventricular end-diastolic pressure thresholds. CONCLUSIONS: In the largest analysis of HDL-P subfractions in HF to date, derangements in HDL-P subfractions were identified that were more severe in HFrEF than HFpEF and were independently associated with adverse outcomes. These data may help refine risk assessment and provide new insights into the complex interaction of HDL and HF pathophysiology.

Improvement in insulin resistance after gastric bypass surgery is correlated with a decline in plasma 2-hydroxybutyric acid.

BACKGROUND: Gastric bypass surgery for weight reduction often corrects dysglycemia in diabetic patients, but a full understanding of the underlying biochemical pathways continues to be investigated. OBJECTIVES: To explore the effects of weight loss by surgical and dietary interventions on plasma metabolites using both targeted and discovery-oriented metabolomics platforms. SETTING: An academic medical center in the United States. METHODS: Improvement in homeostatic model assessment for insulin resistance (HOMA-IR), as an index of insulin resistance, was compared at 6 months in 11 patients that underwent Roux-en-Y gastric bypass against 11 patients that were matched for weight loss in the Weight Loss Maintenance (WLM) program. Metabolites in plasma were evaluated by nontargeted gas chromatography/mass spectrometry for the potential detection of >1100 biochemical markers. RESULTS: Among multiple metabolites detected, 2-hydroxybutyric acid (2-HBA) declined most significantly after 6 months in comparing patients that underwent Roux-en-Y gastric bypass with those in WLM (P < .001), corresponding with declines in HOMA-IR (P = .025). Baseline levels of 2-HBA for all patients were correlated with preintervention levels of HOMA-IR (R2 = .565, P < .001). Moreover, the changes in 2-HBA after 6 months were correlated with changes in HOMA-IR (R2 = .399, P = .0016). CONCLUSIONS: Correlation between insulin resistance and 2-HBA suggests the utility of the latter as an excellent biomarker for tracking glycemic improvement, and offers further insight into the pathways that control diabetes. This is the first report of a decline in 2-HBA in response to bariatric surgery.

Metabolites predict cardiovascular disease events in persons living with HIV: a pilot case-control study.

Introduction: Persons living with HIV (PLWH) are at higher risk for cardiovascular disease (CVD) events than uninfected persons. Current risk-stratification methods to define PLWH at highest risk for CVD events are lacking. Methods: Using tandem flow injection mass spectrometry, we quantified plasma levels of 60 metabolites in 24 matched pairs of PLWH [1:1 with and without known coronary artery disease (CAD)]. Metabolite levels were reduced to interpretable factors using principal components analysis. Results: Factors derived from short-chain dicarboxylacylcarnitines (SCDA) (p = 0.08) and glutamine/valine (p = 0.003) were elevated in CAD cases compared to controls. Conclusion: SCDAs and glutamine/valine may be valuable markers of cardiovascular risk among persons living with HIV in the future, pending validation in larger cohorts.

Brain-derived neurotrophic factor rs6265 (Val66Met) polymorphism is associated with disease severity and incidence of cardiovascular events in a patient cohort.

BACKGROUND: The rs6265 (Val66Met) single-nucleotide polymorphism in the BDNF gene has been related to a number of endophenotypes that have in turn been shown to confer risk for atherosclerotic cardiovascular disease (CVD). To date, however, very few studies have examined the association of the Val66Met single-nucleotide polymorphism with CVD clinical outcomes. METHODS: In a cohort of 5,510 Caucasian patients enrolled in the CATHeterization GENetics (CATHGEN) study at Duke University Hospital between 2001 and 2011, we determined the severity of coronary artery disease (CAD) and CVD event incidence through up to 11.8years of follow-up. We examined the association of Val66Met genotype with time-to-death or myocardial infarction, adjusting for age, sex, CAD risk variables, and CAD severity measures. RESULTS: The Val/Val genotype was associated with a higher risk than Met carriers for clinical CVD events (P=.034, hazard ratio 1.12, 95% CI 1.01-1.24). In addition, compared with Met carriers, individuals with the Val/Val genotype had a greater odds of having more diseased vessels (odds ratio 1.17, 95% CI 1.06-1.30, P=.002), and lower left ventricular ejection fraction (ß=-0.72, 95% CI, -1.42 to -0.02, P=.044). CONCLUSIONS: The Val/Val genotype was associated with greater severity of CAD and incidence of CVD-related clinical events in a patient sample. If these findings are confirmed in further research, intervention studies in clinical groups with the Val/Val genotype could be undertaken to prevent disease and improve prognosis.

Atherogenic Lipoprotein Determinants of Cardiovascular Disease and Residual Risk Among Individuals With Low Low-Density Lipoprotein Cholesterol.

BACKGROUND: Levels of LDL (low-density lipoprotein) cholesterol in the population are declining, and increasing attention is being focused on residual lipid-related pathways of atherosclerotic cardiovascular disease risk beyond LDL cholesterol. Among individuals with low (<130 mg/dL) LDL cholesterol, we undertook detailed profiling of circulating atherogenic lipoproteins in relation to incident cardiovascular disease in 2 populations. METHODS AND RESULTS: We performed proton nuclear magnetic resonance spectroscopy to quantify concentrations of LDL and VLDL (very low-density lipoprotein) particle subclasses in 11 984 JUPITER trial participants (NCT00239681). Adjusted Cox models examined cardiovascular disease risk associated with lipoprotein measures according to treatment allocation. Risk (adjusted hazard ratio [95%CI] per SD increment) among placebo-allocated participants was associated with total LDL particles (1.19 [1.02, 1.38]) and total VLDL particles (1.21 [1.04, 1.41]), as well as apolipoprotein B, non-high-density lipoprotein cholesterol, and triglycerides, but not LDL-c. Rosuvastatin reduced LDL measures but had variable effects on triglyceride and VLDL measures. On-statin levels of the smallest VLDL particle subclass were associated with a 68% per-SD (adjusted hazard ratio 1.68 [1.28, 2.22]) increase in residual risk-this risk was related to VLDL cholesterol and not triglyceride or larger VLDL particles. There was evidence that residual risk prediction during statin therapy could be significantly improved through the inclusion of key VLDL measures (Harrell C-index 0.780 versus 0.712; P<0.0001). In an independent, prospective cohort of 4721 individuals referred for cardiac catheterization (CATHGEN), similar patterns of lipoprotein-related risk were observed. CONCLUSIONS: Atherogenic lipoprotein particle concentrations were associated with cardiovascular disease risk when LDL cholesterol was low. VLDL lipoproteins, particularly the smallest remnant subclass, may represent unused targets for risk prediction and potential therapeutic intervention for reducing residual risk. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00239681.

Plasma acylcarnitines are associated with pulmonary hypertension.

Quantifying metabolic derangements in pulmonary hypertension (PH) by plasma metabolomics could identify biomarkers useful for diagnosis and treatment. The objective of this paper is to test the hypotheses that circulating metabolites are differentially expressed in PH patients compared with controls and among different hemodynamic subtypes of PH associated with left heart disease. We studied patients enrolled in the CATHGEN biorepository with PH (right heart catheterization mPAP ≥ 25 mmHg; n = 280). Of these, 133 met criteria for postcapillary PH, 82 for combined precapillary and postcapillary PH (CpcPH), and 65 for precapillary PH. Targeted profiling of 63 metabolites (acylcarnitines, amino acids, and ketones) was performed using tandem flow injection mass spectrometry. Multivariable linear regression was used to determine differences in metabolite factors derived from a principal components analysis between PH cases, PH subtypes, and non-PH controls. In adjusted models, the metabolite factor loaded with long-chain acylcarnitines was higher in all PH cases versus non-PH controls (P = 0.00008), but did not discriminate between CpcPH and postcapillary PH (P = 0.56). In analyses of subtypes, CpcPH patients had lower levels of factors loaded with urea cycle amino acids and short chain acylcarnitines as compared to controls (P = 0.002 and P = 0.01, respectively) and as compared to postcapillary PH (P = 0.04 and P = 0.02, respectively). Compared to controls, PH was strongly associated with greater concentrations of long-chain acylcarnitines. Postcapillary PH and CpcPH were weakly associated with distinct metabolomic profiles. These findings suggest the presence of unique metabolic abnormalities in subtypes of PH and may reflect underlying pathophysiology.

Apolipoprotein L1 Genetic Variants Are Associated with Chronic Kidney Disease but Not with Cardiovascular Disease in a Population Referred for Cardiac Catheterization.

BACKGROUND: While the association between APOL1 genetic variants and chronic kidney disease (CKD) has been established, their association with cardiovascular disease (CVD) is unclear. This study sought to understand CKD and cardiovascular risk conferred by APOL1 variants in a secondary cardiovascular prevention population. METHODS: Two risk variants in APOL1 were genotyped in African-Americans (n = 1,641) enrolled in the CATHGEN biorepository, comprised of patients referred for cardiac catheterization at Duke University Hospital, Durham, NC, USA (2001-2010). Individuals were categorized as noncarriers (n = 722), heterozygote (n = 771), or homozygote carriers (n = 231) of APOL1 risk alleles. Multivariable logistic regression and Cox proportional hazards models adjusted for CVD risk factors were used to assess the association between APOL1 risk variants and prevalent and incident CKD, prevalent coronary artery disease (CAD), incident CVD events, and mortality. RESULTS: The previously identified association between APOL1 variants and prevalent CKD was confirmed (OR: 1.85, 95% CI: 1.33-2.57, p = 0.0002). No statistically significant associations were detected between APOL1 variants and incident CKD or prevalent CAD, incident CVD events or mortality. Age, type 2 diabetes, and ejection fraction at baseline were significant clinical factors that predicted the risk of incident CKD in a subgroup analysis of APOL1 homozygous individuals. CONCLUSION: APOL1 genetic variants are not associated with CAD or incident CVD events in a cohort of individuals with a high burden of cardiometabolic risk factors. In individuals with homozygous APOL1 status, factors that predicted subsequent CKD included age, presence of type 2 diabetes, and ejection fraction at baseline.

A Novel Protein Glycan-Derived Inflammation Biomarker Independently Predicts Cardiovascular Disease and Modifies the Association of HDL Subclasses with Mortality.

BACKGROUND: Evidence suggests that systemic inflammation may adversely impact HDL function. In this study we sought to evaluate the independent and incremental predictive performance of GlycA-a novel serum inflammatory biomarker that is an aggregate measure of enzymatically glycosylated acute phase proteins-and HDL subclasses on adverse events in a retrospective observational study of a secondary prevention population and to understand a priori defined potential interactions between GlycA and HDL subclasses. METHODS: GlycA and HDL subclasses were measured using proton nuclear magnetic resonance spectroscopy in 7617 individuals in the CATHGEN (CATHeterization GENetics) cardiac catheterization biorepository. RESULTS: GlycA was associated with presence [odds ratio (OR) 1.07 (1.02-1.13), P = 0.01] and extent [OR 1.08 (1.03, 1.12) P < 0.0005] of coronary artery disease and with all-cause mortality [hazard ratio (HR) 1.34 (1.29-1.39), P < 0.0001], cardiovascular mortality [1.37 (1.30-1.45), P < 0.0001] and noncardiovascular mortality [1.46 (1.39-1.54) P < 0.0001] in models adjusted for 10 cardiovascular risk factors. GlycA and smaller HDL subclasses had independent but opposite effects on mortality risk prediction, with smaller HDL subclasses being protective [HR 0.69 (0.66-0.72), P < 0.0001]. There was an interaction between GlycA and smaller HDL subclasses-increasing GlycA concentrations attenuated the inverse association of smaller HDL subclasses with mortality. Adding GlycA and smaller HDL subclasses into the GRACE (Global Registry of Acute Coronary Events) and Framingham Heart Study Risk Scores improved mortality risk prediction, discrimination and reclassification. CONCLUSIONS: These findings highlight the interaction of systemic inflammation and HDL with clinical outcomes and may increase precision for clinical risk assessment in secondary prevention populations.

Metabolomic Profiling Identifies Novel Circulating Biomarkers of Mitochondrial Dysfunction Differentially Elevated in Heart Failure With Preserved Versus Reduced Ejection Fraction: Evidence for Shared Metabolic Impairments in Clinical Heart Failure.

BACKGROUND: Metabolic impairment is an important contributor to heart failure (HF) pathogenesis and progression. Dysregulated metabolic pathways remain poorly characterized in patients with HF and preserved ejection fraction (HFpEF). We sought to determine metabolic abnormalities in HFpEF and identify pathways differentially altered in HFpEF versus HF with reduced ejection fraction (HFrEF). METHODS AND RESULTS: We identified HFpEF cases, HFrEF controls, and no-HF controls from the CATHGEN study of sequential patients undergoing cardiac catheterization. HFpEF cases (N=282) were defined by left ventricular ejection fraction (LVEF) ≥45%, diastolic dysfunction grade ≥1, and history of HF; HFrEF controls (N=279) were defined similarly, except for having LVEF <45%. No-HF controls (N=191) had LVEF ≥45%, normal diastolic function, and no HF diagnosis. Targeted mass spectrometry and enzymatic assays were used to quantify 63 metabolites in fasting plasma. Principal components analysis reduced the 63 metabolites to uncorrelated factors, which were compared across groups using ANCOVA. In basic and fully adjusted models, long-chain acylcarnitine factor levels differed significantly across groups (P<0.0001) and were greater in HFrEF than HFpEF (P=0.0004), both of which were greater than no-HF controls. We confirmed these findings in sensitivity analyses using stricter inclusion criteria, alternative LVEF thresholds, and adjustment for insulin resistance. CONCLUSIONS: We identified novel circulating metabolites reflecting impaired or dysregulated fatty acid oxidation that are independently associated with HF and differentially elevated in HFpEF and HFrEF. These results elucidate a specific metabolic pathway in HF and suggest a shared metabolic mechanism in HF along the LVEF spectrum.

High-density lipoprotein subclass measurements improve mortality risk prediction, discrimination and reclassification in a cardiac catheterization cohort.

BACKGROUND AND AIMS: Recent failures of HDL cholesterol (HDL-C)-raising therapies to prevent cardiovascular disease (CVD) events have tempered the interest in the role of HDL-C in clinical risk assessment. Emerging data suggest that the atheroprotective properties of HDL depend on specific HDL particle characteristics not reflected by HDL-C. The purpose of this study was to determine the association of HDL particle concentration (HDL-P) and HDL subclasses with mortality in a high-risk cardiovascular population and to examine the clinical utility of these parameters in mortality risk discrimination and reclassification models. METHODS: Using nuclear magnetic resonance spectroscopy, we measured HDL-P and HDL subclasses in 3972 individuals enrolled in the CATHGEN coronary catheterization biorepository; tested for association with all-cause mortality in robust clinical models; and examined the utility of HDL subclasses in incremental mortality risk discrimination and reclassification. RESULTS: Over an average follow-up of eight years, 29.6% of the individuals died. In a multivariable model adjusted for ten CVD risk factors, HDL-P [HR, 0.71 (0.67-0.76), p = 1.3e-24] had a stronger inverse association with mortality than did HDL-C [HR 0.93 (0.87-0.99), p = 0.02]. Larger HDL size conferred greater risk and the sum of medium- and small-size HDL particles (MS-HDL-P) conferred less risk. Furthermore, the strong inverse relation of HDL-P levels with mortality was accounted for entirely by MS-HDL-P; HDL-C was not associated with mortality after adjustment for MS-HDL-P. Addition of MS-HDL-P to the GRACE Risk Score significantly improved risk discrimination and risk reclassification. CONCLUSION: HDL-P and smaller HDL subclasses were independent markers of residual mortality risk and incremental to HDL-C in a high-risk CVD population. These measures should be considered in risk stratification and future development of HDL-targeted therapies in high-risk populations.

Metabolomic Quantitative Trait Loci (mQTL) Mapping Implicates the Ubiquitin Proteasome System in Cardiovascular Disease Pathogenesis.

Levels of certain circulating short-chain dicarboxylacylcarnitine (SCDA), long-chain dicarboxylacylcarnitine (LCDA) and medium chain acylcarnitine (MCA) metabolites are heritable and predict cardiovascular disease (CVD) events. Little is known about the biological pathways that influence levels of most of these metabolites. Here, we analyzed genetics, epigenetics, and transcriptomics with metabolomics in samples from a large CVD cohort to identify novel genetic markers for CVD and to better understand the role of metabolites in CVD pathogenesis. Using genomewide association in the CATHGEN cohort (N = 1490), we observed associations of several metabolites with genetic loci. Our strongest findings were for SCDA metabolite levels with variants in genes that regulate components of endoplasmic reticulum (ER) stress (USP3, HERC1, STIM1, SEL1L, FBXO25, SUGT1) These findings were validated in a second cohort of CATHGEN subjects (N = 2022, combined p = 8.4x10-6-2.3x10-10). Importantly, variants in these genes independently predicted CVD events. Association of genomewide methylation profiles with SCDA metabolites identified two ER stress genes as differentially methylated (BRSK2 and HOOK2). Expression quantitative trait loci (eQTL) pathway analyses driven by gene variants and SCDA metabolites corroborated perturbations in ER stress and highlighted the ubiquitin proteasome system (UPS) arm. Moreover, culture of human kidney cells in the presence of levels of fatty acids found in individuals with cardiometabolic disease, induced accumulation of SCDA metabolites in parallel with increases in the ER stress marker BiP. Thus, our integrative strategy implicates the UPS arm of the ER stress pathway in CVD pathogenesis, and identifies novel genetic loci associated with CVD event risk.

ADAM12: a genetic modifier of preclinical peripheral arterial disease.

In prior studies from multiple groups, outcomes following experimental peripheral arterial disease (PAD) differed considerably across inbred mouse strains. Similarly, in humans with PAD, disease outcomes differ, even when there are similarities in risk factors, disease anatomy, arteriosclerotic burden, and hemodynamic measures. Previously, we identified a locus on mouse chromosome 7, limb salvage-associated quantitative trait locus 1 (LSq-1), which was sufficient to modify outcomes following experimental PAD. We compared expression of genes within LSq-1 in Balb/c mice, which normally show poor outcomes following experimental PAD, with that in C57Bl/6 mice, which normally show favorable outcomes, and found that a disintegrin and metalloproteinase gene 12 (ADAM12) had the most differential expression. Augmentation of ADAM12 expression in vivo improved outcomes following experimental PAD in Balb/c mice, whereas knockdown of ADAM12 made outcomes worse in C57Bl/6 mice. In vitro, ADAM12 expression modulates endothelial cell proliferation, survival, and angiogenesis in ischemia, and this appeared to be dependent on tyrosine kinase with Ig-like and EGF-like domain 2 (Tie2) activation. ADAM12 is sufficient to modify PAD severity in mice, and this likely occurs through regulation of Tie2.

Genetic variants associated with vein graft stenosis after coronary artery bypass grafting.

BACKGROUND: Vein graft stenosis after coronary artery bypass grafting (CABG) is common. Identifying genes associated with vein graft stenosis after CABG could reveal novel mechanisms of disease and discriminate patients at risk for graft failure. We hypothesized that genome-wide association would identify these genes. METHODS: We performed a genome-wide association study on a subset of patients presenting for cardiac catheterization for concern of ischemic heart disease, who also underwent CABG and subsequent coronary angiography after CABG for clinical indications (n = 521). Cases were defined as individuals with ≥50% stenosis in any vein graft on any cardiac catheterization, and controls were defined as those who did not have vein graft stenosis on any subsequent cardiac catheterization. Multivariable logistic regression was used to assess the association between single nucleotide polymorphisms (SNPs) and vein graft stenosis. RESULTS: Sixty-nine percent of patients had vein graft failure after CABG. Seven SNPs were significantly associated with vein graft stenosis, including intronic SNPs in the genes PALLD (Rs6854137, P = 3.77 × 10(-6)), ARID1B (Rs184074, P = 5.97 × 10(-6)), and TMEM123 (Rs11225247, P = 8.25 × 10(-6)); and intergenic SNPs near the genes ABCA13 (Rs10232860, P = 4.54 × 10(-6)), RMI2 (Rs9921338, P = 6.15 × 10(-6)), PRM2 (Rs7198849, P = 7.27 × 10(-6)), and TNFSF4 (Rs17346536, P = 9.33 × 10(-6)). CONCLUSIONS: We have identified novel genetic variants that may predispose to risk of vein graft failure after CABG, many within biologically plausible pathways. These polymorphisms merit further investigation, as they could assist in stratifying patients with multi-vessel coronary artery disease, which could lead to alterations in management and revascularization strategy.

Effects of left ventricular assist device support on biomarkers of cardiovascular stress, fibrosis, fluid homeostasis, inflammation, and renal injury.

OBJECTIVES: The purpose of this study was to examine changes in a broad panel of biomarkers following left ventricular assist device (LVAD) support in advanced heart failure (HF). BACKGROUND: LVAD therapy mechanically unloads the failing heart and may result in reversal of certain aspects of the end-stage HF phenotype. Changes in markers of myocardial stress, fibrosis, inflammation, fluid homeostasis, and renal injury in this setting are unknown. METHODS: Amino-terminal pro-B-type natriuretic peptide (NT-proBNP), galectin-3, ST2, copeptin, growth differentiation factor (GDF)-15, C-reactive protein (CRP), and neutrophil gelatinase associated lipocalin (NGAL) levels were measured in frozen plasma collected from 37 individuals prior to continuous flow LVAD implantation and a median of 136 (interquartile range: 94 to 180) days after implantation. RESULTS: The median age of patients was 68 years old. LVAD therapy was associated with significant decreases in NT-proBNP (3,093 to 2,090 pg/ml; p = 0.02), ST2 (67.5 to 45.2 ng/ml, p <0.01), galectin-3 (24.7 to 22.0 ng/ml; p = 0.04), GDF-15 (3,232 to 2,613 ng/l;p <0.001), hs-CRP (22.4 to 11.9 mg/l; p = 0.01), and copeptin (103 to 94 pmol/l; p = 0.003) but not NGAL (132 to 135 ng/ml; p = 0.06). Despite improvement over time, absolute values of each biomarker remained extremely abnormal. Greater reductions in biomarkers were noted in individuals with >25% decrease in NT-proBNP concentrations but reached statistical significance only in the case of galectin-3 (p = 0.01). CONCLUSIONS: The biomarker profile in patients after LVAD placement improves but nonetheless remains significantly abnormal. Our results suggest the need for targeted therapeutic interventions to mitigate such abnormalities and potentially increase rates of myocardial recovery.

Validation of the association between a branched chain amino acid metabolite profile and extremes of coronary artery disease in patients referred for cardiac catheterization.

OBJECTIVE: To validate independent associations between branched-chain amino acids (BCAA) and other metabolites with coronary artery disease (CAD). METHODS: We conducted mass-spectrometry-based profiling of 63 metabolites in fasting plasma from 1983 sequential patients undergoing cardiac catheterization. Significant CAD was defined as CADindex ≥ 32 (at least one vessel with ≥ 95% stenosis; N = 995) and no CAD as CADindex ≤ 23 and no previous cardiac events (N = 610). Individuals (N = 378) with CAD severity between these extremes were excluded. Principal components analysis (PCA) reduced large numbers of correlated metabolites into uncorrelated factors. Association between metabolite factors and significant CAD vs. no CAD was tested using logistic regression; and between metabolite factors and severity of CAD was tested using linear regression. RESULTS: Of twelve PCA-derived metabolite factors, two were associated with CAD in multivariable models: factor 10, composed of BCAA (adjusted odds ratio, OR, 1.20; 95% CI 1.05-1.35, p = 0.005) and factor 7, composed of short-chain acylcarnitines, which include byproducts of BCAA metabolism (adjusted OR 1.30; 95% CI 1.14-1.48, p = 0.001). After adjustment for glycated albumin (marker of insulin resistance [IR]) both factors 7 (p = 0.0001) and 10 (p = 0.004) remained associated with CAD. Severity of CAD as a continuous variable (including patients with non-obstructive disease) was associated with metabolite factors 2, 3, 6, 7, 8 and 9; only factors 7 and 10 were associated in multivariable models. CONCLUSIONS: We validated the independent association of metabolites involved in BCAA metabolism with CAD extremes. These metabolites may be reporting on novel mechanisms of CAD pathogenesis that are independent of IR and diabetes.

Risk factors for 1-year mortality after thoracic endovascular aortic repair.

OBJECTIVE: Thoracic endovascular aortic repair, although physiologically well tolerated, may fail to confer significant survival benefit in some high-risk patients. In an effort to identify patients most likely to benefit from intervention, the present study sought to determine the risk factors for 1-year mortality after thoracic endovascular aortic repair. METHODS: A retrospective review was performed on prospectively collected data from all patients undergoing thoracic endovascular aortic repair from 2002 to 2010 at a single institution. Univariate analysis and multivariate Cox proportional hazards regression analysis were used to identify risk factors associated with mortality within 1 year after thoracic endovascular aortic repair. RESULTS: During the study period, 282 patients underwent at least 1 thoracic endovascular aortic repair; index procedures included descending aortic repair (n = 189), hybrid arch repair (n = 55), and hybrid thoracoabdominal repair (n = 38). The 30-day/in-hospital mortality was 7.4% (n = 21) and the overall 1-year mortality was 19% (n = 54). Cardiopulmonary pathologies were the most common cause of nonperioperative 1-year mortality (22%, n = 12). Multivariate modeling demonstrated 3 variables independently associated with 1-year mortality: age older than 75 years (hazard ratio, 2.26; P = .005), aortic diameter greater than 6.5 cm (hazard ratio, 2.20; P = .007), and American Society of Anesthesiologists class 4 (hazard ratio, 1.85; P = .049). A baseline creatinine greater than 1.5 mg/dL (hazard ratio, 1.79; P = .05) and congestive heart failure (hazard ratio, 1.87; P = .08) were also retained in the final model. These 5 variables explained a large proportion of the risk of 1-year mortality (C statistic = 0.74). CONCLUSIONS: Age older than 75 years, aortic diameter greater than 6.5 cm, and American Society of Anesthesiologists class 4 are independently associated with 1-year mortality after thoracic endovascular aortic repair. These clinical characteristics may help risk-stratify patients undergoing thoracic endovascular aortic repair and identify those unlikely to derive a long-term survival benefit from the procedure.

A functional polymorphism in the 5HTR2C gene associated with stress responses also predicts incident cardiovascular events.

Previously we have shown that a functional nonsynonymous single nucleotide polymorphism (rs6318) of the 5HTR2C gene located on the X-chromosome is associated with hypothalamic-pituitary-adrenal axis response to a stress recall task, and with endophenotypes associated with cardiovascular disease (CVD). These findings suggest that individuals carrying the rs6318 Ser23 C allele will be at higher risk for CVD compared to Cys23 G allele carriers. The present study examined allelic variation in rs6318 as a predictor of coronary artery disease (CAD) severity and a composite endpoint of all-cause mortality or myocardial infarction (MI) among Caucasian participants consecutively recruited through the cardiac catheterization laboratory at Duke University Hospital (Durham, NC) as part of the CATHGEN biorepository. Study population consisted of 6,126 Caucasian participants (4,036 [65.9%] males and 2,090 [34.1%] females). A total of 1,769 events occurred (1,544 deaths and 225 MIs; median follow-up time = 5.3 years, interquartile range = 3.3-8.2). Unadjusted Cox time-to-event regression models showed, compared to Cys23 G carriers, males hemizygous for Ser23 C and females homozygous for Ser23C were at increased risk for the composite endpoint of all-cause death or MI: Hazard Ratio (HR) = 1.47, 95% confidence interval (CI) = 1.17, 1.84, p = .0008. Adjusting for age, rs6318 genotype was not related to body mass index, diabetes, hypertension, dyslipidemia, smoking history, number of diseased coronary arteries, or left ventricular ejection fraction in either males or females. After adjustment for these covariates the estimate for the two Ser23 C groups was modestly attenuated, but remained statistically significant: HR = 1.38, 95% CI = 1.10, 1.73, p = .005. These findings suggest that this functional polymorphism of the 5HTR2C gene is associated with increased risk for CVD mortality and morbidity, but this association is apparently not explained by the association of rs6318 with traditional risk factors or conventional markers of atherosclerotic disease.

Matrix metalloproteinase-9 genetic polymorphisms and the risk for advanced pelvic organ prolapse.

OBJECTIVE: Matrix metalloproteinase-9 (MMP9) is a protease associated with degradation of collagen and elastin. Because increased MMP9 activity in vaginal tissue has been associated with pelvic organ prolapse (POP), we sought to comprehensively estimate MMP9 genetic variants and the risk for advanced prolapse. METHODS: This is a candidate gene association study of women with stage III-IV prolapse (case group, n=239) and women with stage 0-1 prolapse (control group, n=197). We attempted to oversample "extreme" phenotypes, including younger women with severe prolapse and older women without prolapse, in an attempt to concentrate the genetic effect. We used a linkage disequilibrium tagged approach to identify single nucleotide polymorphisms in MMP9 to evaluate in our study. To minimize potential confounding by race, our analysis focused on non-Hispanic white women. We performed multivariable logistic regression to estimate the association between MMP9 single nucleotide polymorphisms and case-control status, adjusting for age and vaginal parity. RESULTS: Women with advanced prolapse were slightly younger (64.8 ± 10.3 compared with 69.0 ± 10.2 years, P<.001) and more likely to have had one or more vaginal deliveries (96.6% compared with 82.2%, P<.001) when compared with control participants. Eight single nucleotide polymorphisms were assessed, which represented 93% coverage of the MMP9 gene. Of these, two were associated with advanced prolapse: 1) rs3918253 (adjusted odds ratio [OR] 0.64, 95% confidence interval [CI] 0.41-1.0, P=.05); and 2) rs3918256 (adjusted OR 0.64, 95% CI 0.41-1.01, P=.05). CONCLUSION: MMP9 is a biologically plausible candidate gene for POP given our results.

Comprehensive analysis of LAMC1 genetic variants in advanced pelvic organ prolapse.

OBJECTIVE: We sought to comprehensively evaluate the association of laminin gamma-1 (LAMC1) and advance pelvic organ prolapse. STUDY DESIGN: We conducted a candidate gene association of patients (n = 239) with stages III-IV prolapse and controls (n = 197) with stages 0-I prolapse. We used a linkage disequilibrium (LD)-tagged approach to identify single-nucleotide polymorphisms (SNPs) in LAMC1 and focused on non-Hispanic white women to minimize population stratification. Additive and dominant multivariable logistic regression models were used to test for association between individual SNPs and advanced prolapse. RESULTS: Fourteen SNPs representing 99% coverage of LAMC1 were genotyped. There was no association between SNP rs10911193 and advanced prolapse (P = .34). However, there was a trend toward significance for SNPs rs1413390 (P = .11), rs20563 (P = .11), and rs20558 (P = .12). CONCLUSION: Although we found that the previously reported LAMC1 SNP rs10911193 was not associated with nonfamilial prolapse, our results support further investigation of this candidate gene in the pathophysiology of prolapse.

Metabolic profiles predict adverse events after coronary artery bypass grafting.

OBJECTIVE: Clinical models incompletely predict the outcomes after coronary artery bypass grafting. Novel molecular technologies can identify biomarkers to improve risk stratification. We examined whether metabolic profiles can predict adverse events in patients undergoing coronary artery bypass grafting. METHODS: The study population comprised 478 subjects from the CATHGEN biorepository of patients referred for cardiac catheterization who underwent coronary artery bypass grafting after enrollment. Targeted mass spectrometry-based profiling of 69 metabolites was performed in frozen, fasting plasma samples collected before surgery. Principal components analysis and Cox proportional hazards regression modeling were used to assess the relation between the metabolite factor levels and a composite outcome of postcoronary artery bypass grafting myocardial infarction, the need for percutaneous coronary intervention, repeat coronary artery bypass grafting, and death. RESULTS: During a mean follow-up period of 4.3 ± 2.4 years, 126 subjects (26.4%) experienced an adverse event. Three principal components analysis-derived factors were significantly associated with an adverse outcome on univariate analysis: short-chain dicarboxylacylcarnitines (factor 2, P = .001); ketone-related metabolites (factor 5, P = .02); and short-chain acylcarnitines (factor 6, P = .004). These 3 factors remained independently predictive of an adverse outcome after multivariate adjustment: factor 2 (adjusted hazard ratio, 1.23; 95% confidence interval, 1.10-1.38; P < .001), factor 5 (odds ratio, 1.17; 95% confidence interval, 1.01-1.37; P = .04), and factor 6 (odds ratio, 1.14; 95% confidence interval, 1.02-1.27; P = .03). CONCLUSIONS: Metabolic profiles are independently associated with adverse outcomes after coronary artery bypass grafting. These profiles might represent novel biomarkers of risk that can augment existing tools for risk stratification of coronary artery bypass grafting patients and might elucidate novel biochemical pathways that mediate risk.