Objectives: Determine relationships between calcification and cognitive function. Background: Dementia affects over 5.4 million Americans; prevalence will quadruple in the next 50 years. Coronary artery calcification (CAC), a measure of subclinical atherosclerosis, may affect cognitive function through microvascular brain effects. Abdominal aortoiliac calcification (AAC) generally precedes CAC and may provide earlier risk determination. Effects of calcification on cognition have not been studied in African Americans (AA). Methods: The 2008-2011 GENOA CAC cohort consists of AA sibships (n=657, mean age 69 [range 40-98], 74% women, 82% hypertensive) enriched with hypertension from Jackson, MS with computed tomography (CT) Agatston calcification measures. Cognition was assessed in 4 domains: global cognitive function (Mini-Mental State Examination); processing speed (Digit Symbol Substitution and Trail Making A); memory (RAVLT and WAIS-III Incidental Learning); and executive function (Trail Making B). Relationships of cognition (standardized) and calcification (log base 2 scale accounting for skewness) were examined using linear regressions with GEE to account for sibship clustering, adjusting parsimoniously for age, sex, and education. Results: Doublings of CAC were significantly associated with poorer processing speed (ß=-0.049 [-0.072, -0.025] p=0.000) and executive function (ß=-0.037 [-0.070, -0.003] p=0.031) in younger subjects and with poorer global function (ß=-0.0648 [-0.096, -0.020] p=0.000), memory (ß=-0.034 [-0.060, -0.007] p=0.013), and processing speed (ß=-0.051 [-0.076, -0.025] p=0.000) in older subjects. Doublings of AAC were significantly associated with poorer processing speed (ß=-0.0381 [-0.056, -0.020] p=0.000) and executive function (ß=-0.045 [-0.070, -0.020] p=0.000) in younger subjects and poorer processing speed (ß=-0.050 [-0.075, -0.025] p=0.000) in older subjects. Conclusions: Calcification is associated with processing speed in young and old AA with prevalent cardiovascular risk factors and may be differentially associated with other cognitive domains by age. Processing speed in particular may be a domain affected early in the calcification process, warranting further study. This supports existing literature addressing the relationship between calcification and cognitive function in ethnically diverse cohorts. Further studies can focus on the temporal and causal relationships between calcification and cognition across age in AA samples enriched for hypertension to identify predictive factors associated with future cognitive decline.
Abstract P020: Associations of Markers of Inflammation with Nocturnal BP Dipping Status Using Two Common Dipping Definitions: the Genetic Epidemiology Network of Arteriopathy
Background: Compared to those with natural nocturnal blood pressure (BP) decreases, those lacking nocturnal BP decreases (“non-dippers”) are at greater risk of cardiovascular disease (CVD). Substantial evidence also supports a role of chronic systemic inflammation in the pathogenesis of CVD. The purpose of this study was to examine associations of markers of inflammation with two common definitions of BP dipping status using 24-hour ambulatory blood pressure (AMBP) readings. Methods: AMBP monitoring and assays of C-reactive protein (CRP), interleukin-6 (IL-6), e-selectin, tissue inhibitor of metalloproteinase-2 (TIMP-2), and a selection of thirteen other inflammatory-pathway biomarkers were performed in 722 participants (mean age 64 [range 42-83] years, 36% men, 39% black, 83% hypertensive) in the Genetic Epidemiology Network of Arteriopathy (GENOA) Study (2001-2004). Non-dippers were classified using two common definitions: (1) nocturnal systolic and diastolic BP both decreased by <10% compared to daytime values [“dual non-dippers”, n=161 (22%)], and (2) nocturnal SBP decreased by <10% [“systolic non-dippers”, n=380 (53%)]. Logistic regressions, fit with generalized estimating equations to account for sibship clustering, yielded odds ratios (OR) of dipping status for log-transformed inflammatory biomarkers, adjusted for age, race, and sex. Results: IL-6 (range 0-37 pg/ml) was associated with dual non-dipping status (OR=1.55 [95%CI: 1.03, 2.32] p=0.035), translating into a 55% increase in the likelihood of being a dual non-dipper for every approximate doubling of IL-6. IL-6 (OR=1.63 [1.13, 2.35] p=0.009) and CRP (OR=1.35 [1.08,1.68] p=0.008) overall, as well as e-selectin (OR=0.49 [0.28, 0.87] p=0.014) and TIMP-2 (OR=0.54 [0.30,0.98] p=0.041) in hypertensive subjects were associated with systolic non-dipping status. Conclusions: These results suggest that non-dipping classification should be approached with prudence, as the two different criteria may influence conclusions about predictive marker associations. In addition, markers involved in direct versus inhibitory inflammation pathways may operate differentially across patient subgroups. Our findings support the link between inflammation and non-dipping circadian BP patterns and provide novel information on markers and definitions which may be useful for early detection and subsequent prevention of CVD.
Abstract P253: Proton Pump Inhibitor Use is Positively Associated with Incidence of Cardiovascular Disease
Introduction: Proton pump inhibitors (PPIs) are used by an estimated 29 million Americans. PPIs increase the levels of asymmetrical dimethylarginine, a known risk factor for cardiovascular disease (CVD). Data from a select population of patients with CVD suggest that PPI use is associated with an increased risk of stroke, heart failure, and coronary heart disease. The impact of PPI use on incident CVD is largely unknown in the general population. Hypothesis: We hypothesized that PPI users have a higher risk of incident total CVD, coronary heart disease, stroke, and heart failure compared to nonusers. To demonstrate specificity of association, we additionally hypothesized that there is not an association between use of H 2 -blockers - another commonly used class of medications with similar indications as PPIs - and CVD. Methods: We used the Rochester Epidemiology Project’s medical records-linkage system to identify all residents of Olmsted County, MN on our baseline date of January 1, 2004 (N=140217). We excluded persons who did not grant permission for their records to be used for research, were <18 years old, had a history of CVD, had missing data for any variable included in our model, or had evidence of PPI use within the previous year.We followed our final cohort (N=58175) for up to 12 years. The administrative censoring date for CVD was 1/20/2014, for coronary heart disease was 8/3/2016, for stroke was 9/9/2016, and for heart failure was 1/20/2014. Time-varying PPI ever-use was ascertained using 1) natural language processing to capture unstructured text from the electronic health record, and 2) outpatient prescriptions. An incident CVD event was defined as the first occurrence of 1) validated heart failure, 2) validated coronary heart disease, or 3) stroke, defined using diagnostic codes only. As a secondary analysis, we calculated the association between time-varying H 2 -blocker ever-use and CVD among persons not using H 2 -blockers at baseline. Results: After adjustment for age, sex, race, education, hypertension, hyperlipidemia, diabetes, and body-mass-index, PPI use was associated with an approximately 50% higher risk of CVD (hazard ratio [95% CI]: 1.51 [1.37-1.67]; 2187 CVD events), stroke (hazard ratio [95% CI]: 1.49 [1.35-1.65]; 1928 stroke events), and heart failure (hazard ratio [95% CI]: 1.56 [1.23-1.97]; 353 heart failure events) compared to nonusers. Users of PPIs had a 35% greater risk of coronary heart disease than nonusers (95% CI: 1.13-1.61; 626 coronary heart disease events). Use of H 2 -blockers was also associated with a higher risk of CVD (adjusted hazard ratio [95% CI]: 1.23 [1.08-1.41]; 2331 CVD events). Conclusions: PPI use is associated with a higher risk of CVD, coronary heart disease, stroke and heart failure. Use of a drug with no known cardiac toxicity - H 2 -blockers - was also associated with a greater risk of CVD, warranting further study.
Abstract 16160: Common Autosomal Variants are Associated With Bicuspid Aortic Valve in Turner Syndrome
Introduction: The prevalence of bicuspid aortic valves (BAV) is enriched thirty-fold in women with Turner Syndrome (TS) in comparison with the general population. Hypothesis: Common autosomal variants influence the development of BAV in TS women, who may be uniquely sensitized to these variants by the loss of one X chromosome. We sought to identify autosomal BAV susceptibility genes in a cohort of TS women (average age 30 years, 38% BAV, 18% coarctation). Methods: A total of 106 TS women of European ancestry with BAV and 173 TS women with tricuspid aortic valves were genotyped on Illumina Omni-Express arrays. Valve phenotypes were determined by independent review of echocardiograms from the enrolling sites. Tests of association were performed using logistic regression without adjustment for covariates and were summarized in a meta-analysis. Results: Xp dosage was inversely and quantitatively associated with BAV status (P=0.02). Large, recurrent copy number variants in 1p36.13, 3q29, 8p23.1 and 9p24.3 were significantly enriched in BAV cases. After exclusion of 26 outlier samples in multidimensional scaling analysis, there was no significant genomic inflation (lambda= 1.02). The strongest genome-wide association signals were observed in 1p36.23, 3q23, 12q21.2, 18q21 and 22q13.31, and did not overlap with previously reported loci for BAV. A total of 13 SNPs in 18q21 were positively associated with BAV (OR=2.5-4.3) with a minimum P value of 1x10-7. Replication of these regions in independent groups of cases is ongoing. Conclusion: Our results demonstrate that autosomal variants with large magnitudes of effect contribute to BAV in TS women, confirming our hypothesis, and provide evidence for gene-gene interactions in BAV formation.
Abstract P045: Differential Associations of Inflammation and Cognitive Function in African and European Americans
Dementia affects approximately 5 million people in the United States and cost $183 billion in 2011, with African Americans (AA) experiencing a disproportionate burden of dementia compared to European Americans (EA). Inflammation is considered by many to be a potential mediator in the development of cognitive dysfunction. High sensitivity C-reactive protein (CRP) and tumor necrosis factor-α (TNF-α), increasingly measured by the soluble TNF receptors 1 & 2 (sTNFRI1, sTNFR2), are among the most frequently cited inflammatory markers associated with dementia and are also elevated in vascular disease. Few studies have compared associations of inflammatory markers with cognitive function in EA and AA. We examined the association of CRP, sTNFR1 and sTNFR2 with cognitive function using detailed neuropsychological assessments in the Genetic Epidemiology Network of Arteriopathy (GENOA)-Genetics of Microangiopathic Brain Injury (GMBI) participants, a cohort considered at high risk of vascular disease due to family history (> 2 individuals in sibships with hypertension at age <60 years) and high prevalence rates of hypertension (74%), diabetes (27%), and obesity (51%). Cognitive function was measured across 5 cognitive domains: global cognitive function, processing speed, language, memory, and executive function. In AA, higher sTNFR2 was associated with poorer performance across all five domains. Higher sTNFR1 and CRP were associated with slower processing speed. In EA, higher sTNFR1 was associated with slower processing speed. CRP and sTNFR2 were not associated with cognitive function in EA. Inflammatory markers in this cohort were associated differentially across cognitive domains in AA and EA, and may reflect racial differences in vascular responses to inflammation.
Genetics of Hypertension, Target-Organ Complications, and Response to Therapy
We recently reported altered cardiovascular structure and function in heart failure (HF) patients based on the Arg16/Gly and Gln27/Glu beta‐2 adrenergic receptor (ADRB2) polymorphisms. The purpose of this study was to extend the echocardiographic analysis based on haplotype combination of ADRB2 at nucleotides −654, 46 79, 252, 491, 523, in a larger database of HF patients (n=126, age 56±1yr, LV ejection fraction, LVEF 29±1%, BMI 28±0.4kg/m 2 , mean±SEM) and healthy controls (n=100, age 50±2yr, LVEF 63±0.7%, BMI 25±0.3kg/m 2 ). The most common haplotypes in both HF and control were 2, 8, and 12 (2=AACGCC, 8=GGCACA, and 12=GGGGCC, for nucleotides −654, 46, 79, 252, 491, and 523). Cardiac function did not differ according to haplotype pairs in the control subjects. In HF, the widest discrepancies were between haplotype pair 2/2 (which includes the Arg16+Gln27 homozygotes) and haplotype pair 12/12 (which includes the Gly16+Glu27 homozygotes), respectively: 2/2 displayed lower cardiac index (2.3±0.1 v 2.7±0.1 l/min/m 2 ), greater left atrial diameter (53±2 v 47±2 mm), shorter LV decel time (185±11 v 224±14 msec), and greater right ventricular pressure (44±2 v 33±2 mmHg) p<0.05 for all). These data suggest that in HF, haplotype variation of the ADRB2 is associated with differences in cardiac function, and SNP positions 16 and 27 remain major loci of interest. Support: K23RR‐17520, HL‐71478.
Gene‐by‐Gene Interactions Between Phenylethanolamine N‐Methyltransferase and the Beta‐2 Adrenergic Receptor and the Ventricular Response to Exercise
Epinephrine is a sympathomimetic which is derived from phenylalanine and tyrosine. The final step of epinephrine synthesis, the conversion from norepinephrine, relies on phenylethanolamine N‐methyltransferase (PNMT). The beta‐2 adrenergic receptor (ADRB2) binds to epinephrine and has several common functional polymorphisms including a Glycine (Gly) for Arginine (Arg) substitution at amino acid 16. We assessed the effect of the gene‐to‐gene interaction of these proteins on the ventricular response to exercise in healthy humans (n=69, age=29±6yrs, ht=174±10cm, wt=71±13kg). We found that within the 2*1 haplotype of the 5′FR, which has previously demonstrated greater epinephrine synthesis compared to 2*7 haplotype, the Arg16 genotype demonstrates lower stroke volume (SV) than the Gly16 genotype despite similar epinephrine levels and synthesis rates (Arg16= 75±5, Gly16=89±6ml/beat). Similarly, within the 2*7 haplotype of the 5′FR, which has demonstrated attenuated epinephrine synthesis compared to 2*1, the Arg16 genotype demonstrates a smaller SV than the Gly16 genotype (Arg16= 59±3, Gly16=78±6ml/beat). Additionally, the Arg16 and Gly16 subjects within the 2*1 haplotype of PNMT have greater stroke volume than their ADRB2 counterparts of the 2*7 haplotype of PNMT. These data demonstrate an interaction between the genes that encode PNMT and ADRB2 on the ventricular response to exercise.
Arg16/Gly β
2
‐adrenergic receptor polymorphism and forearm blood flow following dietary sodium restriction
The Gly allele of the Arg16/Gly β 2 ‐adrenergic receptor polymorphism has been associated with hypertension in a linkage analysis in Rochester, MN. Gly homozygotes have greater forearm β 2 ‐receptor mediated vasodilation than Arg after a normal Na + diet (150 mmol/day), and the difference is mediated by endothelial NO. To test the hypothesis that dietary Na + restriction affects β 2 ‐mediated dilation in these groups, we measured forearm blood flow (FBF, plethysmography) during brachial arterial infusion of isoproterenol (ISO) after 5 days of low dietary Na + (10 mmol/day), in healthy subjects homozygous for Arg (n=15, 8 women, 29 ± 8 yrs, mean ± SD) vs. Gly (n=17, 7 women, 31 ± 7 yrs). Baseline FBF did not differ between groups. ISO caused a significant increase in FBF that was not different based on genotype (P = 0.51, main effect of genotype; P = 0.72, genotype‐by‐ISO‐interaction). For example, the highest response to ISO was 10.3 ± 5.5 in Arg and 12.0 ± 4.4 ml/100 ml forearm vol/min in Gly (P t‐test = 0.33). NO inhibition with L‐NMMA decreased baseline FBF, and significantly blunted the response to ISO, but there was no evidence to suggest the responses were influenced by genotype (P = 0.89, genotype‐by‐ISO‐by‐L‐NMMA interaction). We conclude that greater NO‐mediated β 2 ‐receptor vasodilation in Gly homozygotes is no longer apparent following dietary Na + restriction, suggesting that greater dilator function in Gly homozygotes during normal Na + intake may be a protective vascular mechanism in a population where the Gly allele is associated with hypertension. Support: HL‐63328, GCRC RR‐00585, NCRR K23‐17520.