Cardiac function assessed by myocardial deformation in adult polycystic kidney disease patients.

BACKGROUND: Patients with autosomal dominant polycystic kidney disease (ADPKD) have an increased risk of cardiovascular morbidity and mortality. Impaired left ventricular (LV) global longitudinal strain (GLS) can be a sign of subclinical cardiac dysfunction even in patients with otherwise preserved ejection fraction (EF). Transmitral early filling velocity to early diastolic strain rate (E/SRe) is a novel measure of LV filling pressure, which is often affected early in cardiac disease. METHODS: A total of 110 ADPKD patients not on dialysis were included in this prospective study. All patients underwent an extensive echocardiographic examination including two-dimensional speckle tracking. GLS and strain rates were measured. The distribution of GLS and E/SRe was determined and patient characteristics were compared by median levels of GLS (- 17.8%) and E/SRe (91.4 cm). Twenty healthy participants were included as control group. RESULTS: There was a significantly worse GLS in the ADPKD patients (mean: - 17.8 ± 2.5%) compared to the healthy controls (mean: - 21.9 ± 1.9%), p < 0.001. The same was true for E/SRe (mean: 10.0 ± 0.3 cm) compared to the control group (mean: 6.5 ± 0.3 cm), p < 0.001. In simple logistic regression, male gender (OR: 4.74 [2.10-10.71], p < 0.001), fasting glucose (odds ratio (OR) 1.05 [1.01-1.10], p = 0.024), htTKV (OR: 1.07 [1.01-1.13], p = 0.013), HDL cholesterol (OR: 0.97 [0.94, 0.996], p = 0.025), triglycerides (OR: 1.01 [1.00-1.02], p = 0.039), hemoglobin (OR: 1.50 [1.11-2.04], p = 0.009), and ß-blocker use (OR: 1.07 [1.01, 1.13], p = 0.013) were all associated with higher GLS. After multivariate logistic regression with backward model selection, only male gender (OR: 5.78 [2.27-14.71], p < 0.001) and ß-blocker use (OR: 14.00 [1.60, 122.51], p = 0.017) remained significant. In simple logistic regression models, BMI (OR: 1.11 [1.02-1.20], p = 0.015), systolic blood pressure (OR: 1.03 [1.00-1.06], p = 0.027) and ß-blocker use (OR: 17.12 [2.15-136.20], p = 0.007) were associated with higher E/SRe - a novel measure of left ventricular filling pressure. After backward elimination, only ß-blocker use (OR: 17.22 [2.16, 137.14], p = 0.007) remained significant. CONCLUSION: Higher GLS and E/SRe are common in ADPKD patients, even in patients with preserved eGFR and normal left ventricular EF. GLS and E/SRe may aid in cardiovascular risk stratification in patients with ADPKD as they represent early markers of cardiac dysfunction.

Selective association of electrocardiographic abnormalities with insulin sensitivity and beta-cell function in type 2 diabetes mellitus: a cross-sectional analysis.

BACKGROUND: We investigated the association of electrocardiographic (ECG) abnormalities with markers of insulin resistance and pancreatic beta-cell dysfunction in a cross-sectional study of type 2 diabetes patients. METHODS: Electrocardiographic criteria were evaluated in the Penn Diabetes Heart Study participants (n = 1671; 64% male; 61% Caucasian), including a sub-sample (n = 710) that underwent oral glucose tolerance testing. The Matsuda Insulin Sensitivity Index and homeostasis model assessment of insulin resistance (HOMA-IR) estimated insulin sensitivity; Insulinogenic Index and homeostasis model assessment of beta-cell function assessed beta-cell function. Multivariable regression modelling was used to analyse associations of ECG changes with these indices. RESULTS: In unadjusted analyses, subjects in the highest quartile of Matsuda index had the lowest prevalence of Q-waves (6.3% versus 15.3%, p = 0.005). In adjusted models, an inverse association was seen between Q-waves and log Matsuda index [one standard deviation increase; OR = 0.59 (95% CI 0.43-0.87 p = 0.001)]. In the full Penn Diabetes Heart Study, there was a direct association between Q-waves and HOMA-IR [one standard deviation increase; OR = 1.43 (95% CI 1.13-1.81, p = 0.003)]. In adjusted models, left ventricular hypertrophy also was inversely associated with Matsuda index and directly with HOMA-IR. Higher Insulinogenic Index scores were associated with a lower prevalence of nonspecific ST changes [OR = 0.78 (95% CI 0.62-0.98, p = 0.032)]. CONCLUSIONS: In type 2 diabetic patients, both oral glucose tolerance testing-derived and HOMA-derived measures of insulin resistance were associated with pathologic Q-waves and left ventricular hypertrophy on ECGs. Copyright © 2016 John Wiley & Sons, Ltd.

Differential association of plasma angiopoietin-like proteins 3 and 4 with lipid and metabolic traits.

OBJECTIVE: Angiopoietin-like protein 3 (ANGPTL3) and 4 (ANGPTL4) are secreted proteins that inhibit lipoprotein lipase in vitro. Genetic variants at the ANGPTL3 and ANGPTL4 gene loci are significantly associated with plasma lipid traits. The aim of this study was to evaluate the association of plasma ANGPTL3 and ANGPTL4 concentrations with lipid and metabolic traits in a large community-based sample. APPROACH AND RESULTS: Plasma ANGPTL3 and ANGPTL4 levels were measured in 1770 subjects using a validated ELISA assay. A Pearson unadjusted correlation analysis and a linear regression analysis adjusting for age, sex, and race were performed. ANGPTL3 levels were significantly positively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels (both P<2×10(-5)) but not triglycerides. In contrast, ANGPTL4 levels were significantly negatively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol (both P<2×10(-5)) and positively associated with triglycerides (P=0.003). In addition, ANGPTL4, but not ANGPTL3, levels were significantly positively associated with fasting blood glucose and metabolic syndrome. CONCLUSIONS: Despite having similar biochemical effects in vitro, plasma ANGPTL3 and ANGPTL4 concentrations have nearly opposite relationships with plasma lipids. ANGPTL4 is strongly negatively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol and positively with multiple features of the metabolic syndrome including triglycerides, whereas ANGPTL3 is positively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol and not with metabolic syndrome traits including triglycerides. Although ANGPTL3 and ANGPTL4 both inhibit lipoprotein lipase in vitro and influence lipoprotein metabolism in vivo, the physiology of these related proteins and their effects on lipoproteins is clearly divergent and complex.

Genome-wide association study of coronary heart disease and its risk factors in 8,090 African Americans: the NHLBI CARe Project.

Coronary heart disease (CHD) is the leading cause of mortality in African Americans. To identify common genetic polymorphisms associated with CHD and its risk factors (LDL- and HDL-cholesterol (LDL-C and HDL-C), hypertension, smoking, and type-2 diabetes) in individuals of African ancestry, we performed a genome-wide association study (GWAS) in 8,090 African Americans from five population-based cohorts. We replicated 17 loci previously associated with CHD or its risk factors in Caucasians. For five of these regions (CHD: CDKN2A/CDKN2B; HDL-C: FADS1-3, PLTP, LPL, and ABCA1), we could leverage the distinct linkage disequilibrium (LD) patterns in African Americans to identify DNA polymorphisms more strongly associated with the phenotypes than the previously reported index SNPs found in Caucasian populations. We also developed a new approach for association testing in admixed populations that uses allelic and local ancestry variation. Using this method, we discovered several loci that would have been missed using the basic allelic and global ancestry information only. Our conclusions suggest that no major loci uniquely explain the high prevalence of CHD in African Americans. Our project has developed resources and methods that address both admixture- and SNP-association to maximize power for genetic discovery in even larger African-American consortia.

Normal Values and Reference Ranges for the Ratio of Transmitral Early Filling Velocity to Early Diastolic Strain Rate: The Copenhagen City Heart Study.

BACKGROUND: The ratio of transmitral early filling velocity to early diastolic strain rate (E/e'sr) has recently emerged as a measure of left ventricular filling pressure. Reference values are needed for this new parameter for it to be used clinically. METHODS: Healthy participants from a prospective general population study, the Fifth Copenhagen City Heart Study, were assessed to establish reference values for E/e'sr derived from two-dimensional speckle-tracking echocardiography. The prevalence of abnormal E/e'sr was assessed in participants with cardiovascular risk factors or specific diseases. RESULTS: The population comprised 1,623 healthy participants (median age, 45; interquartile range, 32-56; 61% female). The upper reference limit for E/e'sr in the population was 79.6 cm. Following multivariable adjustment, male participants exhibited significantly higher E/e'sr than female participants (upper reference limit for male participants, 83.7 cm; for female participants, 76.5 cm). For both sexes, E/e'sr increased in a curvilinear fashion with age such that the largest increases in E/e'sr were observed in participants >45 years. In the entire CCHS5 population with E/e'sr available (n = 3,902), increasing age, body mass index, systolic blood pressure, male sex, estimated glomerular filtration rate, and diabetes were associated with E/e'sr (all P < .05). Total cholesterol was associated with a less steep increase in E/e'sr. Abnormal E/e'sr was seldomly observed in participants with normal diastolic function but became more frequent in participants with increasing grades of diastolic dysfunction (normal, mild, moderate, severe [abnormal E/e'sr for each grade: 4.4% vs 20.0% vs 16.2% vs 55.6%, respectively]). CONCLUSION: The E/e'sr differs between sexes and is age dependent such that E/e'sr increases with advancing age. Therefore, we established sex- and age-stratified reference values for E/e'sr.

Gender differences in the association of C-reactive protein with coronary artery calcium in type-2 diabetes.

OBJECTIVES: Plasma C-reactive protein (CRP) is associated with cardiovascular disease (CVD), but effects may vary by gender and degree of CVD risk. Whether CRP has value as a CVD risk marker in type-2 diabetes (T2DM) is unclear. We examined whether CRP has gender differences in association with coronary artery calcium (CAC) in diabetic and nondiabetic samples without clinical CVD. METHODS: We performed cross-sectional analyses of gender influence on CRP association with CAC in the Penn Diabetes Heart Study (N = 1299 with T2DM), the Study of Inherited Risk of Coronary Atherosclerosis (N = 860 nondiabetic subjects) and a combined sample. RESULTS: Female gender was associated with higher plasma CRP in diabetic and nondiabetic samples after adjustment for covariates. There was a strong interaction by gender in the association of CRP with CAC (interaction P < 0·001). In diabetic women, CRP was associated with higher CAC even after further adjustment for age, race, medications, metabolic syndrome, Framingham risk score and body mass index [Tobit ratio 1·60, 95% CI (1·03-2·47)]. Although this relationship was attenuated in nondiabetic women, the combined sample maintained this association in fully adjusted models [1·44, 95% CI (1·13-1·83)]. There was no association of CRP with CAC in either diabetic or nondiabetic men. CONCLUSIONS: CRP may be a useful marker of cardiovascular risk in women, particularly in diabetic women who otherwise have no known CVD. Prospective studies are needed to better assess the gender differences in CRP utility and the use of CRP in T2DM.

The clinical application of the ratio of transmitral early filling velocity to early diastolic strain rate: a systematic review and meta-analysis.

BACKGROUND: The ratio of transmitral early filling velocity to early diastolic strain rate (E/e'sr) has recently emerged as a novel and accurate non-invasive measure of left ventricular (LV) filling pressure. This systematic review and meta-analysis aimed to give an overview of the possible clinical implications of E/e'sr. METHODS: We conducted a systematic review and meta-analysis of all studies involving E/e'sr. Of 598 identified studies, 16 met our inclusion criteria. Studies involving E/e'sr either investigated its prognostic value (n = 9) or its correlation with invasively measured LV filling pressure (n = 7). RESULTS: The pooled meta-analysis showed a significant correlation between E/e'sr and pulmonary capillary wedge pressure (PCWP) measured invasively across the studies assessing this relationship (Cohen's d = 3.90 95% CI [2.38-6.39], p < 0.001) and between E/e'sr and left ventricle end-diastolic pressure (LVEDP) measured invasively across the studies assessing this relationship (Cohen's d = 5.30 95% CI [2.83-9.96], p < 0.001). The pooled analysis of the prognostic studies showed that E/e'sr was a significant predictor of adverse outcomes after multivariable adjustment across the different study populations in a random effects model (overall estimated HR: 1.58 95% CI [1.28-1.96], p < 0.001, per 1 m increase). CONCLUSION: E/e'sr correlates well with invasive measures of LV filling pressure. In addition, E/e'sr provides significant prognostic information across various patient populations. Further studies are needed to test if E/e'sr has an advantage to E/e'.

Resistin gene variation is associated with systemic inflammation but not plasma adipokine levels, metabolic syndrome or coronary atherosclerosis in nondiabetic Caucasians.

OBJECTIVE: Resistin causes insulin resistance and diabetes in mice whereas in humans it is linked to inflammation and atherosclerosis. Few human genetic studies of resistin in inflammation and atherosclerosis have been performed. We hypothesized that the -420C>G putative gain-of-function resistin variant would be associated with inflammatory markers and atherosclerosis but not with metabolic syndrome or adipokines in humans. DESIGN AND METHODS: We examined the association of three resistin polymorphisms, -852A>G, -420C>G and +157C>T, and related haplotypes with plasma resistin, cytokines, C-reactive protein (CRP), adipokines, plasma lipoproteins, metabolic syndrome and coronary artery calcification (CAC) in nondiabetic Caucasians (n = 851). RESULTS: Resistin levels were higher, dose-dependently, with the -420G allele (CC 5.9 +/- 2.7 ng/ml, GC 6.5 +/- 4.0 ng/ml and GG 7.2 +/- 4.8 ng/ml, trend P = 0.04) after age and gender adjustment [fold higher for GC + GG vs. CC; 1.07 (1.00-1.15), P < 0.05)]. The -852A>G single nucleotide polymorphism (SNP) was associated with higher soluble tumour necrosis factor-receptor 2 (sol-TNFR2) levels in fully adjusted models [1.06 (95% CI 1.01-1.11), P = 0.01)]. The estimated resistin haplotype (GGT) was associated with sol-TNFR2 (P = 0.04) and the AGT haplotype was related to CRP (P = 0.04) in the fully adjusted models. Resistin SNPs and haplotypes were not associated with body mass index (BMI), fasting glucose, insulin resistance, metabolic syndrome, adipokines or CAC scores. CONCLUSIONS: Despite modest associations with plasma resistin and inflammatory biomarkers, resistin 5' variants were not associated with metabolic parameters or coronary calcification. This suggests that resistin is an inflammatory cytokine in humans but has little influence on adiposity, metabolic syndrome or atherosclerosis.

Cardiac MRI T2* in Liver Transplant Candidates: Application and Performance of a Novel Imaging Technique to Identify Patients at Risk for Poor Posttransplant Cardiac Outcomes.

BACKGROUND: In end-stage liver disease, alterations in iron metabolism can lead to iron overload and development of iron overload cardiomyopathy. In liver transplant candidates, evaluation for cardiac iron overload and dysfunction can help to identify candidates at increased risk for peritransplant morbidity and mortality, though recommendations for pretransplant evaluation of cardiac iron overload are not standardized. Cardiac Magnetic Resonance Imaging T2* (CMRI-T2*) is a validated method to quantify cardiac iron deposition, with normal T2* value of 20 ms or greater. In this study, we sought to identify the incidence and predictors of iron overload by CMRI-T2* and to evaluate the impact of cardiac and iron overload on morbidity and mortality after liver transplantation. METHODS: In this retrospective single-center cohort study, all liver transplant candidates who underwent a pretransplant CMRI-T2* between January 1, 2008, and June 30, 2016, were included to analyze the association between clinical characteristics and low T2* using logistic regression. RESULTS: One hundred seventy-nine liver transplant candidates who received CMRI-T2* were included. Median age was 57 years, 73.2% were male, and 47.6% were white. 49.7% had hepatitis C and 2.8% had hemochromatosis. Median Model for End-Stage Liver Disease score was 25. 65.2% were Child-Pugh C. In multivariable logistic regression, T2* less than 20 ms (n = 35) was associated with Model for End-Stage Liver Disease score of 25 or greater (odds ratio [OR], 3.65; P = 0.007), Child-Pugh C (OR, 3.42; P = 0.03), and echocardiographic systolic ejection fraction less than 65% (OR, 2.24; P = 0.01). Posttransplant heart failure occurred exclusively in recipients with T2* less than 15 ms. Survival was worse in T2* 10 to 14.9 versus T2* of 20 ms or greater (hazard ratio, 3.85; P = 0.003), but not for 15 to 19.9 versus T2* of 20 ms or greater. CONCLUSIONS: Severity of liver disease and systolic dysfunction is associated with T2* less than 20 ms, though there was no difference in posttransplant outcomes between T2* 15 to 19.9 and T2* 20 ms or greater, suggesting that individuals with T2* of 15 ms or greater may be suitable transplant candidates. CMRI-T2* is an additional diagnostic tool in evaluating transplant candidates at high risk for posttransplant cardiac complications.

Ascending and descending thoracic aorta calcification in type 2 diabetes mellitus.

BACKGROUND: Calcification of the thoracic aorta is a risk factor for cardiovascular disease and peripheral arterial disease but has not been well studied in diabetics. In addition, many studies consider aortic calcium as a single anatomic entity, whereas calcification of the ascending and descending portions of the thoracic aorta may represent separate phenotypes. We sought to characterize the prevalence of ascending and descending aortic calcium among diabetics and to assess their associations with cardiovascular risk factors, coronary artery calcium, and peripheral arterial disease. METHODS: Within the Penn Diabetes Heart Study, a cross-sectional study of subjects with type 2 diabetes mellitus but without coronary or renal disease, we quantified Agatston scores of the ascending and descending thoracic aorta in 1739 subjects (63% male, 61% Caucasian). Multivariate logistic and Tobit regressions were used to assess associations with cardiovascular risk factors, coronary calcium, and peripheral arterial disease. RESULTS: Of all subjects, 54% had thoracic aortic calcium; of these, 37% had calcium solely in the ascending thoracic aorta and 20% solely in the descending thoracic aorta. In multivariate regression, age, Caucasian race, systolic blood pressure, low-density lipoprotein cholesterol, smoking, and diabetes duration were independently associated with calcium of both the ascending and descending thoracic aorta (P < .001 for all). Ascending and descending aortic calcium were each independently associated with coronary calcium in multivariate regression, but only calcification of the descending thoracic aortic was associated with low ankle-brachial index. CONCLUSION: Ascending and descending thoracic aortic calcium have similar associations with traditional cardiovascular risk factors in diabetics and are independently associated with coronary artery calcium. Only calcium in the descending aorta is associated with peripheral arterial disease. Delineation of both phenotypes may provide information about the individualized vascular disease and risk profile of patients with type 2 diabetes mellitus.

Leptin and incident cardiovascular disease: the Multi-ethnic Study of Atherosclerosis (MESA).

OBJECTIVE: Higher serum leptin levels have been associated with a modestly higher incidence of cardiovascular disease in studies involving mostly Caucasian men. We aimed to assess the hypothesis that higher baseline levels of serum leptin are associated with higher risk of future cardiovascular disease in a diverse cohort. METHODS: The Multi-Ethnic Study of Atherosclerosis (MESA) is a modern, community-based, ethnically-diverse, and sex-balanced prospective cohort study of US adults free from cardiovascular disease. Serum leptin was measured in an ancillary study in 2002-2005. This analysis included 1905 MESA participants with baseline leptin and incident cardiovascular event data. Leptin levels were modeled as a log-transformed continuous variable and multivariable-adjusted Cox regression was performed for the primary outcome of hard cardiovascular disease, including coronary heart disease and stroke. RESULTS: The median follow-up was 7.6 years (25th-75th 7.1-8.3) with 7051 and 6738 person-years of follow-up in women and men. A hard cardiovascular disease event occurred in 47 women and 63 men. The age- and ethnicity-adjusted hazard ratio estimates for a 1 standard deviation increase in ln(leptin) were 1.16 in women (95% CI 0.78-1.73, p = 0.46) and 0.91 (95% CI 0.69-1.20, p = 0.51) in men. Pooling sexes, and adjusting for sex in addition to age and ethnicity, estimates were 0.98 (95% CI 0.78-1.23, p = 0.89). With additional adjustment for cardiovascular risk factors, the results remained nonsignificant: 0.87 (95% CI 0.68-1.11, p = 0.26). CONCLUSION: In conclusion, in a modern, US prospective cohort study of multi-ethnic women and men of multi-ethnic backgrounds, leptin levels are not associated with incident cardiovascular events.

Differential associations of oral glucose tolerance test-derived measures of insulin sensitivity and pancreatic ß-cell function with coronary artery calcification and microalbuminuria in type 2 diabetes.

OBJECTIVE We evaluated relationships of oral glucose tolerance testing (OGTT)-derived measures of insulin sensitivity and pancreatic ß-cell function with indices of diabetes complications in a cross-sectional study of patients with type 2 diabetes who are free of overt cardiovascular or renal disease. RESEARCH DESIGN AND METHODS A subset of participants from the Penn Diabetes Heart Study (n = 672; mean age 59 ± 8 years; 67% male; 60% Caucasian) underwent a standard 2-h, 75-g OGTT. Insulin sensitivity was estimated using the Matsuda Insulin Sensitivity Index (ISI), and ß-cell function was estimated using the Insulinogenic Index. Multivariable modeling was used to analyze associations between quartiles of each index with coronary artery calcification (CAC) and microalbuminuria. RESULTS The Insulinogenic Index and Matsuda ISI had distinct associations with cardiometabolic risk factors. The top quartile of the Matsuda ISI had a negative association with CAC that remained significant after adjusting for traditional cardiovascular risk factors (Tobit ratio -0.78 [95% CI -1.51 to -0.05]; P = 0.035), but the Insulinogenic Index was not associated with CAC. Conversely, the highest quartile of the Insulinogenic Index, but not the Matsuda ISI, was associated with lower odds of microalbuminuria (OR 0.52 [95% CI 0.30-0.91]; P = 0.022); however, this association was attenuated in models that included duration of diabetes. CONCLUSIONS Lower ß-cell function is associated with microalbuminuria, a microvascular complication, while impaired insulin sensitivity is associated with higher CAC, a predictor of macrovascular complications. Despite these pathophysiological insights, the Matsuda ISI and Insulinogenic Index are unlikely to be translated into clinical use in type 2 diabetes beyond established clinical variables, such as obesity or duration of diabetes.

Non-compressible arterial disease and the risk of coronary calcification in type-2 diabetes.

OBJECTIVE: Ankle-brachial index (ABI) screening is recommended for the detection of asymptomatic peripheral arterial disease (PAD) in at-risk populations, including diabetics. A low ABI identifies obstructive lower extremity vascular disease and predicts CVD events and increased mortality. A high ABI represents non-compressible arterial disease (NCAD), and is also associated with increased mortality and vascular events. Our objective is to investigate whether low and high ABI have distinct patterns of association with cardiovascular disease (CVD) risk factors and subclinical atherosclerosis in individuals with type-II diabetes mellitus. METHODS: The Penn Diabetes Heart Study (PDHS) is a prospective observational cohort of diabetic individuals without clinically evident CVD. Multivariate logistic and Tobit linear regression were used to compare CVD risk factors and coronary artery (CAC) among 1863 subjects with PAD (ABI ≤ 0.9), NCAD (ABI ≥ 1.4 or non-compressible) or normal ABI (0.91-1.39). RESULTS: Compared to those with normal ABI, PAD was associated with smoking, obesity, and lower HDL-c; while diabetes duration and reduced renal function were associated with NCAD. Both PAD and NCAD were independently associated with increased CAC compared to those with normal ABI, and these relationships were not attenuated in multiply adjusted models. CONCLUSION: NCAD bears a distinct relationship to traditional CVD risk factors among diabetics, though like PAD is independently associated with increased CAC. These findings support the recognition of NCAD as a high-risk phenotype and provide additional relevance to ABI screening in diabetics.

Cardiovascular risk factors and mitral annular calcification in type 2 diabetes.

OBJECTIVE: Mitral annular calcification (MAC) is a degenerative process of the mitral annulus associated with cardiac disease and stroke. Although thought to be more prevalent in type 2 diabetes (T2DM), MAC remains poorly characterized in this population, due to confounding by renal and cardiac disease. Our goal was to study the risk factors for MAC in a sample of T2DM subjects without renal and cardiac disease. METHODS: The Penn Diabetes Heart Study (PDHS) is a cross-sectional study of diabetic individuals without clinical cardiovascular or renal disease. We quantified and analyzed MAC Agatston scores in baseline cardiac CTs from 1753 individuals. Logistic and tobit regression were used to assess MAC's relationship with risk factors and coronary artery calcium (CAC). RESULTS: MAC was present in 12.0% of subjects, with a median Agatston score of 72.3 [Interquartile range (22.2-256.9)]. Older age, female gender, Caucasian race, and longer diabetes duration were independently associated with both the presence and extent MAC even after controlling for CAC; however, hypertension, hyperlipidemia, tobacco use, CRP levels, and other comorbidities were not associated. CAC was strongly associated with MAC [OR of 4.0 (95% CI 2.4-6.6)] in multivariable models. CONCLUSIONS: Age, female gender, Caucasian race, and diabetes duration were associated with the presence and extent of MAC in T2DM subjects, independent of CAC, which was also strongly associated with MAC. These data suggest that additional mechanisms for MAC formation in diabetics may exist which are distinct from those related to generalized atherosclerosis and deserve further investigation.

C-reactive protein modifies the association of plasma leptin with coronary calcium in asymptomatic overweight individuals.

Evidence suggests putative interactions of leptin and C-reactive protein (CRP) in the pathogenesis of adiposity-related atherosclerotic cardiovascular disease (CVD). Therefore, we investigated whether CRP levels modify the relationship of leptin levels with coronary artery calcium (CAC). We examined 1,460 asymptomatic individuals from two community-based cross-sectional studies coordinated at a single, university-based research center. We focused on subjects who were overweight or obese (BMI ≥25) given greater biologic plausibility in this setting. In multivariable CAC models, we analyzed the interaction of log-transformed plasma leptin levels with higher CRP levels as defined by three cut-points: two clinically based (2 mg/l, 3 mg/l) and one dataset specific (sex-specific upper quartile). The association of plasma leptin with CAC was modified by higher CRP regardless of cut-point (interaction term P values all <0.01 in fully adjusted models). Leptin levels were associated with CAC in those with high, but not low CRP levels (e.g., tobit ratio for a 1 unit increase in ln(leptin) (95% CI): 2.18 (1.29-3.66) if CRP level ≥3 mg/l; N = 461 vs. 0.94 (0.67-1.31) if CRP levels <3 mg/l; N = 999) in fully adjusted models. No interaction with CRP was present in control analyses with adiponectin, BMI and waist circumference. In conclusion, in asymptomatic overweight and obese adults, increased leptin levels were independently associated with increased CAC in the presence of high, but not low CRP levels, supporting a leptin-CRP interface in atherosclerosis risk.

Lipoprotein(a) is strongly associated with coronary artery calcification in type-2 diabetic women.

BACKGROUND: Lp(a), implicated in both atherogenesis and thrombosis pathways, varies significantly by demographic and metabolic factors, providing challenges for its use in Coronary Heart Disease (CHD) risk. The purpose of this study was to investigate whether type-2 diabetic subjects, relative to non-diabetics, might benefit more from Lp(a) measurement in the prediction of CHD risk, as measured by coronary artery calcium (CAC). METHODS: We performed cross sectional analyses in two community-based studies: the Penn Diabetes Heart Study [N = 1299 with type-2 diabetes] and the Study of Inherited Risk of Coronary Atherosclerosis [N = 860 without diabetes]. RESULTS: Blacks had 2-3 fold higher Lp(a) levels than whites in diabetic and non-diabetic samples. There was significant difference by gender (interaction p<0.001), but not race, in the association of Lp(a) with CAC in type-2 diabetic subjects. In age and race adjusted analysis of diabetic women, Lp(a) was associated with CAC [Tobit regression ratio 2.76 (95% CI 1.73-4.40), p<0.001]. Adjustment for exercise, medications, Framingham risk score, metabolic syndrome, BMI, CRP and hemoglobin A1c attenuated this effect, but the association of Lp(a) with CAC remained significant [2.25, (1.34-3.79), p = 0.002]. This relationship was further maintained in women stratified by race, or by the use of HRT or lipid lowering drugs. In contrast, Lp(a) was not associated with CAC in diabetic men, nor in non-diabetic men and women. CONCLUSIONS: Lp(a) is a strong independent predictor of CAC in type-2 diabetic women, regardless of race, but not in men. Lp(a) does not relate to CAC in men or women without type-2 diabetes.

Comparison of high-density lipoprotein cholesterol to apolipoprotein A-I and A-II to predict coronary calcium and the effect of insulin resistance.

High-density lipoprotein (HDL) cholesterol and its apolipoproteins each capture unique lipid and cardiometabolic information important to risk quantification. It was hypothesized that metabolic factors, including insulin resistance and type 2 diabetes, would confound the association of HDL cholesterol with coronary artery calcification (CAC) and that apolipoprotein A-I (apoA-I) and/or apolipoprotein A-II (apoA-II) would add to HDL cholesterol in predicting CAC. Two community-based cross-sectional studies of white subjects were analyzed: the Penn Diabetes Heart Study (PDHS; n = 611 subjects with type 2 diabetes, 71.4% men) and the Study of Inherited Risk of Coronary Atherosclerosis (SIRCA; n = 803 subjects without diabetes, 52.8% men) using multivariable analysis of apoA-I, apoA-II, and HDL cholesterol stratified by diabetes status. HDL cholesterol was inversely associated with CAC after adjusting for age and gender in whites with type 2 diabetes (tobit ratio for a 1-SD increase in HDL cholesterol 0.58, 95% confidence interval [CI] 0.44 to 0.77, p <0.001) as well as those without diabetes (tobit ratio 0.72, 95% CI 0.59 to 0.88, p = 0.001). In contrast, apoA-I was a weaker predictor in subjects with (tobit ratio 0.64, 95% CI 0.45 to 0.90, p = 0.010) and without (tobit ratio 0.79, 95% CI 0.66 to 0.94, p = 0.010) diabetes, while apoA-II had no association with CAC. Control for metabolic variables, including triglycerides, waist circumference, and homeostasis model assessment of insulin resistance, attenuated these relations, particularly in subjects without diabetes. In likelihood ratio test analyses, HDL cholesterol added to apoA-I, apoA-II, and atherogenic apolipoprotein B lipoproteins but improved CAC prediction over metabolic factors only in subjects with diabetes. In conclusion, HDL cholesterol outperformed apoA-I and apoA-II in CAC prediction, but its association with CAC was attenuated by measures of insulin resistance.

Pathway-Wide Association Study Implicates Multiple Sterol Transport and Metabolism Genes in HDL Cholesterol Regulation.

Pathway-based association methods have been proposed to be an effective approach in identifying disease genes, when single-marker association tests do not have sufficient power. The analysis of quantitative traits may be benefited from these approaches, by sampling from two extreme tails of the distribution. Here we tested a pathway association approach on a small genome-wide association study (GWAS) on 653 subjects with extremely high high-density lipoprotein cholesterol (HDL-C) levels and 784 subjects with low HDL-C levels. We identified 102 genes in the sterol transport and metabolism pathways that collectively associate with HDL-C levels, and replicated these association signals in an independent GWAS. Interestingly, the pathways include 18 genes implicated in previous GWAS on lipid traits, suggesting that genuine HDL-C genes are highly enriched in these pathways. Additionally, multiple biologically relevant loci in the pathways were not detected by previous GWAS, including genes implicated in previous candidate gene association studies (such as LEPR, APOA2, HDLBP, SOAT2), genes that cause Mendelian forms of lipid disorders (such as DHCR24), and genes expressing dyslipidemia phenotypes in knockout mice (such as SOAT1, PON1). Our study suggests that sampling from two extreme tails of a quantitative trait and examining genetic pathways may yield biological insights from smaller samples than are generally required using single-marker analysis in large-scale GWAS. Our results also implicate that functionally related genes work together to regulate complex quantitative traits, and that future large-scale studies may benefit from pathway-association approaches to identify novel pathways regulating HDL-C levels.

Type 2 diabetes does not attenuate racial differences in coronary calcification.

AIMS: Coronary artery calcification (CAC) is a strong predictor of atherosclerotic cardiovascular disease (CVD). Whites appear to have a higher prevalence of CAC than African-Americans (AAs), but it is unknown if type 2 diabetes, a major cardiovascular risk factor, attenuates this difference. We investigated the relationship of race and CAC in a sample of patients with type 2 diabetes without clinical CVD. METHODS: multivariable analyses of self-reported ethnicity and CAC scores, stratified by gender, in 861 subjects [32% AA, 66.9% male] with type 2 diabetes. RESULTS: AA race was associated with lower CAC scores in age-adjusted models in males [Tobit ratio for AAs vs. Whites 0.14 (95% CI 0.08-0.24, p<0.001)] and females [Tobit ratio 0.26 (95% CI 0.09-0.77, p=0.015)]. This persisted in men after adjustment for traditional, metabolic and inflammatory risk factors, but adjustment for plasma triglycerides [0.48 (95% CI 0.15-1.49, p=0.201)] and HOMA-IR [0.28 (95% CI 0.08-1.03, p=0.055)] partially attenuated the association in women. CONCLUSIONS: relative to African-Americans, White race is a strong predictor of CAC, even in the presence of type 2 diabetes. The relationship in women appears less robust possibly due to gender differences in metabolic risk factors.