Copenhagen City Heart Study Research Articles

SCARB1 Gene Variants Are Associated With the Phenotype of Combined High High-Density Lipoprotein Cholesterol and High Lipoprotein (a).

SR-B1 (scavenger receptor class B type 1), encoded by the gene SCARB1, is a lipoprotein receptor that binds both high-density lipoprotein (HDL) and low-density lipoprotein. We reported that SR-B1 is also a receptor for lipoprotein (a) (Lp(a)), mediating cellular uptake of Lp(a) in vitro and promoting clearance of Lp(a) in vivo. Although genetic variants in SCARB1 are associated with variations in HDL level, no SCARB1 variants affecting Lp(a) have been reported. In an index subject with high levels of HDL cholesterol and Lp(a), SCARB1 was sequenced and demonstrated a missense mutation resulting in an S129L substitution in exon 3. To follow up, 2 cohorts (GeneSTAR, the family-based Genetic Study of Atherosclerosis Risk [n=543], and CCHS, the population-based Copenhagen City Heart Study [n=5835]) were screened for combined HDL cholesterol and Lp(a) elevations. Subjects with the extreme phenotype (HDL >80 mg/dL and Lp(a) >100 nmol/L in GeneSTAR, n=8, and >100 mg/dL in CCHS, n=9) underwent sequencing of SCARB1 exons; 15 of 18 from the combined population demonstrated genetic variants, including rare or uncommon missense or splice site mutations in 9 and homozygous synonymous variants in 6. Functional studies with 4 of the SCARB1 variants (c.386C>T, c.631-14T>G, c.4G>A, and c.631-53mC>T & c.726+55mCG>CA) showed decreased receptor function in vitro. Human SCARB1 gene variants are associated with a new lipid phenotype, characterized by high levels of both HDL cholesterol and Lp(a). SCARB1 exonic variants often result in diminished function of translated SR-B1 via reduced binding/intracellular transport of Lp(a).

Long telomeres and cancer risk among 95 568 individuals from the general population.

Results regarding telomere length and cancer risk are conflicting. We tested the hypothesis that long telomeres are associated with increased risk of any cancer and specific cancer types in genetic and observational analyses. Individuals (N = 95 568) from the Copenhagen City Heart Study and the Copenhagen General Population Study had the telomere length-associated genotypes rs7726159 (TERT), rs1317082 (TERC), and rs2487999 (OBFC1) determined, and 65 176 had telomere length measured. A total of 10 895 individuals had had a cancer diagnosis. Endpoints were any cancer and 25 specific cancer types. We conducted Cox regression analyses and logistic regression analyses. The three genotypes were combined as an allele sum. Telomere length increased 67 base-pairs [95% confidence interval (CI) 61-74] per allele. In logistic regression models, the per-allele odds ratio (OR) for cancer was 1.05 (95% CI 1.03-1.07) for the allele sum, 1.05 (1.02-1.09) for rs7726159, 1.05 (1.02-1.08) for rs1317082 and 1.07 (1.02-1.12) for rs2487999. In contrast, the hazard ratio for any cancer was 1.01 (1.00-1.01) per 200-base-pair increase in telomere length in multivariable adjusted observational analysis. In genetic analyses according to specific cancer types, the per-allele odds ratio was 1.19 (1.12-1.27) for melanoma and 1.14 (1.06-1.22) for lung cancer. Genetic determinants of long telomeres are associated with increased cancer risk, particularly melanoma and lung cancer. This genetic predisposition to enhanced telomere maintenance may represent a survival advantage for pre-cancerous cells, allowing for multiple cell divisions leading to cancer development.

COPD epidemiology – the Copenhagen experience

The Copenhagen City Heart Study (CCHS) was set up in the 1970's, modelled on the Framingham Study and initiated by Drs Gorm Jensen and Peter Schnohr, both cardiologists. By chance, spirometry was included and assessed in the 14,223 subjects surveyed. Subjects have subsequently been followed up after 5, 15, 25 and 30 years, and the CCHS has formed the basis of the Copenhagen General Population Study (CGPS), led by Prof Børge Nordestgaard and including 110,000 subjects from Copenhagen suburbs, all with questionnaires, blood biobank, spirometry, ECG, and register linkage for follow-up.

Occupational physical activity, but not leisure-time physical activity increases the risk of atrial fibrillation: The Copenhagen City Heart Study.

Previous findings regarding physical activity and risk of incident atrial fibrillation (AF) are controversial, focusing on leisure-time physical activity (LTPA) and without distinguishing it from occupational physical activity (OPA). Our aim was to study the association between physical activity and risk of AF, with special attention to the possible divergent effects of OPA and LTPA. In a prospective, observational cohort study, 17,196 subjects were included from the Copenhagen Population Register. All participants had a physical examination, a 12-lead electrocardiogram (ECG), and answered a questionnaire regarding health and physical activity. Participants without previously diagnosed AF who answered adequately regarding OPA and LTPA were included. LTPA and OPA were each graded into four levels. Follow-up were carried out between 1981-1983, 1991-1994, and 2001-2003. Information regarding hospitalization and mortality was drawn from the National Patient Registry and the Registry of Causes of Death. Outcome was incident AF as determined by follow-up ECG or register diagnosis. In univariable Cox regression analysis all sub-groups of OPA had a significant higher risk of AF compared to moderate OPA. When adjusting for confounders, the risk remained significantly increased for high OPA (hazard ratio (HR) 1.21 (95% confidence interval (CI) 1.02-1.43), p = 0.028), and very high OPA (HR 1.39 (95% CI 1.03-1.88), p = 0.034). We found no significant association between LTPA and incident AF. High and very high OPA were associated with a significantly increased risk of incident AF. LTPA was not associated with risk of incident AF.

Cardiovascular risk prediction: Can Systematic Coronary Risk Evaluation (SCORE) be improved by adding simple risk markers? Results from the Copenhagen City Heart Study.

European society of cardiology (ESC) guidelines recommend that cardiovascular disease (CVD) risk stratification in asymptomatic individuals is based on the Systematic Coronary Risk Evaluation (SCORE) algorithm, which estimates individual 10-year risk of death from CVD. We assessed the potential improvement in CVD risk stratification of 19 easily available risk markers by adding them to the SCORE algorithm. We followed 8476 individuals without prior CVD or diabetes from the Copenhagen City Heart study. The 19 risk markers were: major and minor electrocardiographic (ECG) abnormalities, heart rate, family history (of ischaemic heart disease), body mass index (BMI), waist-hip ratio, walking duration and pace, leisure time physical activity, forced expiratory volume (FEV)1%pred, household income, education, vital exhaustion, high-density lipoprotein (HDL) cholesterol, triglycerides, apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB), high-sensitive C-reactive protein (hsCRP) and fibrinogen. With the exception of family history, BMI, triglycerides and minor ECG changes, all risk markers remained significantly associated with CVD mortality after adjustment for SCORE variables. However, the addition of the remaining 15 risk markers resulted in only small changes in discrimination calculated by area under the curve (AUC) and integrated discrimination improvement (IDI) and no improvement in net reclassification improvement (NRI). HsCRP improved AUC by 0.006 (p = 0.015) and IDI by 0.012 (p = 0.002); FEV1%pred improved AUC by 0.006 (p = 0.032) and IDI by 0.006 (p = 0.029). In the intermediate risk group FEV1%pred, education, vital exhaustion and ApoA1 all improved NRI but FEV1%pred was the only risk marker to significantly improve both IDI, AUC and NRI. The SCORE algorithm predicted CVD mortality in a Danish cohort well. Despite strong association with CVD mortality, the individual addition of 19 easily available risk makers to the SCORE model resulted in small risk stratification improvements.

Alcohol consumption and risk of atrial fibrillation: Observational and genetic estimates of association.

The aim of this study was to test the hypothesis that alcohol consumption, both observational (self-reported) and estimated by genetic instruments, is associated with a risk of atrial fibrillation and to determine whether people with high cardiovascular risk are more sensitive towards alcohol than people with low risk. We used data for a total of 88,782 men and women from the Copenhagen City Heart Study 1991-1994 and 2001-2003 and the Copenhagen General Population Study 2003-2010. Information on incident cases of atrial fibrillation was obtained from a validated nationwide register. As a measure of alcohol exposure, both self-reported consumption and genetic variations in alcohol metabolizing genes (ADH1B/ADH1C) were used as instrumental variables. The endpoint was admission to hospital for atrial fibrillation as recorded in a validated hospital register. A total of 3493 cases of atrial fibrillation occurred during follow-up. High alcohol consumption was associated with a risk of atrial fibrillation among men, but not among women. Among the men who drank 28-35 and 35+ drinks/week, the hazards ratios were 1.40 (95% confidence interval 1.09-1.80) and 1.62 (95% confidence interval 1.27-2.05) compared with men who drank < 1 drink/week. Using genotypes as instrumental variables did not reveal a higher risk. Associations in those with high cardiovascular risk were similar to those at lower risk. Observational alcohol consumption was associated with a higher risk of atrial fibrillation in men. In women, only a high alcohol intake (28+ drinks/week) was associated with a higher risk. Participants with a high cardiovascular risk were no more sensitive towards alcohol than those at low risk. Genetic analysis did not support a causal relationship of linear association between alcohol intake and atrial fibrillation.

PCSK9 R46L Loss-of-Function Mutation Reduces Lipoprotein(a), LDL Cholesterol, and Risk of Aortic Valve Stenosis.

Novel, low-density lipoprotein (LDL) cholesterol-lowering proprotein convertase subtilisin/kexin type-9 (PCSK9) inhibitors also lower lipoprotein(a) levels, but the effect on aortic valve stenosis and myocardial infarction is unknown. We tested the hypothesis that the PCSK9 R46L loss-of-function mutation is associated with lower levels of lipoprotein(a) and with reduced risk of aortic valve stenosis and myocardial infarction. We used two prospective cohort studies of the general population and one patient-based cohort. Cohort studies selected at random individuals of Danish descent. We studied 103 083 individuals from the Copenhagen General Population Study, the Copenhagen City Heart Study, and the Copenhagen Ischemic Heart Disease Study. Lipoprotein(a), LDL cholesterol, and PCSK9 R46L genotype and diagnoses of aortic valve stenosis and myocardial infarction from national registries; lipoprotein(a) was measured from 49,617 individuals. Median (interquartile range) lipoprotein(a) levels were 10 (5-30) mg/dl for PCSK9 R46L noncarriers, 9 (4-32) mg/dl for heterozygotes, and 8 (4-42) mg/dl for homozygotes (trend P = .02). The corresponding values for LDL cholesterol levels were 124 (101-147) mg/dl, 104 (85-132) mg/dl, and 97 (85-128) mg/dl, respectively (trend P = 2 × 10(-52)). PCSK9 R46L carriers vs noncarriers had an age- and sex-adjusted odds ratio of 0.64 (95% confidence interval, 0.44-0.95) for aortic valve stenosis, 0.77 (0.65-0.92) for myocardial infarction, and 0.76 (0.64-0.89) for aortic valve stenosis or myocardial infarction. PCSK9 R46L carriers have lower levels of lipoprotein(a) and LDL cholesterol as well as reduced risk of aortic valve stenosis and myocardial infarction. This indirectly suggests that PCSK9 inhibitors may have a role in patients with aortic valve stenosis.

Change in Body Mass Index Associated With Lowest Mortality in Denmark, 1976-2013.

Research has shown a U-shaped pattern in the association of body mass index (BMI) with mortality. Although average BMI has increased over time in most countries, the prevalence of cardiovascular risk factors may also be decreasing among obese individuals over time. Thus, the BMI associated with lowest all-cause mortality may have changed. To determine whether the BMI value that is associated with the lowest all-cause mortality has increased in the general population over a period of 3 decades. Three cohorts from the same general population enrolled at different times: the Copenhagen City Heart Study in 1976-1978 (n = 13,704) and 1991-1994 (n = 9482) and the Copenhagen General Population Study in 2003-2013 (n = 97,362). All participants were followed up from inclusion in the studies to November 2014, emigration, or death, whichever came first. For observational studies, BMI was modeled using splines and in categories defined by the World Health Organization. Body mass index was calculated as weight in kilograms divided by height in meters squared. Main outcome was all-cause mortality and secondary outcomes were cause-specific mortality. The number of deaths during follow-up was 10,624 in the 1976-1978 cohort (78% cumulative mortality; mortality rate [MR], 30/1000 person-years [95%CI, 20-46]), 5025 in the 1991-1994 cohort (53%; MR, 16/1000 person-years [95%CI, 9-30]), and 5580 in the 2003-2013 cohort (6%;MR, 4/1000 person-years [95%CI, 1-10]). Except for cancer mortality, the association of BMI with all-cause, cardiovascular, and other mortality was curvilinear (U-shaped). The BMI associated with the lowest all-cause mortality increased by 3.3 from the 1976-1978 cohort compared with the 2003-2013 cohort. [table: see text] The multivariable-adjusted hazard ratios for all-cause mortality for BMI of 30 or more vs BMI of 18.5 to 24.9 were 1.31 (95%CI, 1.23-1.39;MR, 46/1000 person-years [95%CI, 32-66] vs 28/1000 person-years [95%CI, 18-45]) in the 1976-1978 cohort, 1.13 (95%CI, 1.04-1.22; MR, 28/1000 person-years [95%CI, 17-47] vs 15/1000 person-years [95%CI, 7-31]) in the 1991-1994 cohort, and 0.99 (95%CI, 0.92-1.07;MR, 5/1000 person-years [95%CI, 2-12] vs 4/1000 person-years [95%CI, 1-11]) in the 2003-2013 cohort. CONCLUSIONS AND RELEVANCE Among 3 Danish cohorts, the BMI associated with the lowest all-cause mortality increased by 3.3 from cohorts enrolled from 1976-1978 through 2003-2013. Further investigation is needed to understand the reason for this change and its implications.

Self-reported occupational physical activity and cardiorespiratory fitness: Importance for cardiovascular disease and all-cause mortality.

This study aimed to investigate whether workers with the combination of high occupational physical activity (OPA) and low cardiorespiratory fitness have an increased risk of cardiovascular disease (CVD) and all-cause mortality. Using multivariable Cox proportional hazards regression, we analyzed 2190 males and 2534 females from the Copenhagen City Heart Study, aged 20-67 years and with no known CVD at study entry in 1991-1994, for the risk of CVD and all-cause mortality from independent, stratified and combinations of self-reported OPA (ie, low, moderate and high) and cardiorespiratory fitness (low, same and higher as peers) at baseline. During a median follow-up of 18.5 years, 257 and 852 individuals died from CVD and any cause, respectively. In the fully-adjusted model, an increased risk for CVD mortality was found for those with low compared to high self-reported cardiorespiratory fitness [hazard ratio (HR) 2.17, 95% confidence interval (95% CI) 1.40-3.38), for those with high compared to low OPA (HR 1.45, 95% CI 1.05-2.00), and for those with high compared to low OPA within the strata of low self-reported cardiorespiratory fitness (HR 2.83, 95% CI 1.24-6.46). Moreover, those with the combination of high OPA and low self-reported cardiorespiratory fitness had an increased risk for CVD mortality compared to those with the combination of low OPA and high self-reported cardiorespiratory fitness (HR 6.22, 95% CI 2.67-14.49). Rather similar, but lower risk estimates were found for all-cause mortality. These findings may have important implications for CVD prevention among workers with excessive cardiovascular strain at work.

Psychosocial risk factors for the metabolic syndrome: A prospective cohort study

Background/ObjectivesMetabolic deregulations and development of metabolic syndrome may be an important pathway underlying the relationship between stress and cardiovascular disease. We aim to estimate the effect of a comprehensive range of psychosocial factors on the risk of developing metabolic syndrome in men and women. MethodsThe study population consisted of 3621 men and women from the Copenhagen City Heart Study who were free of metabolic syndrome at baseline and reexamined after 10years. The data was analyzed by multivariable logistic regression models adjusted for age, education, income, menopausal status and life style factors. ResultsWe found major life events in adult life (OR 1.48, 95% CI 0.93 to 2.36) and major life events at work (OR 2.75, 95% CI 1.38 to 5.50), lacking a confidant (OR 1.94, 95% CI 1.07 to 3.53) and dissatisfaction with social network (OR 1.53, 95% CI 1.11 to 2.11) to be risk factors for developing the metabolic syndrome in women, while vital exhaustion (OR 2.09, 95% CI 0.95 to 4.59) and intake of sleep medications (OR 2.54, 95% CI 0.92 to 5.96) may play a more important role in men. ConclusionsExperiencing major life events in work and adult life and/or dysfunctional social networks is a risk factor for metabolic syndrome in women, and stress reactions such as vital exhaustion and intake of sleep medications may play a more important role in the development of metabolic syndrome men.

High body mass index and cancer risk-a Mendelian randomisation study.

High body mass index (BMI) has been associated with increased risk of some cancer. Whether these reflect causal associations is unknown. We examined this issue. Using a Mendelian randomisation approach, we studied 108,812 individuals from the general population. During a median of 4.7years of follow-up (range 0-37), 8002 developed non-skin cancer, 3347 non-melanoma skin cancer, 1396 lung cancer, 637 other smoking related cancers, 1203 colon cancer, 159 kidney cancer, 1402 breast cancer, 1062 prostate cancer, and 2804 other cancers. Participants were genotyped for five genetic variants associated with BMI. Two Danish general population studies, the Copenhagen General Population and the Copenhagen City Heart Study. In observational analyses, overall risk of non-melanoma skin cancer was 35% (95% confidence interval 28-42%) lower and risk of lung cancer 32% (19-43%) lower in individuals with a BMI≥30 versus 18.5-24.9kg/m(2). Corresponding risk of breast cancer was 20% (0-44%) higher in postmenopausal women. BMI was not associated with risk of colon, kidney, other smoking related cancers, prostate cancer, or other cancers. In genetic analyses, carrying 7-10 versus 0-4 BMI increasing alleles was associated with a 3% higher BMI (P<0.001), but not with risk of cancer. In instrumental variable analysis for a 10kg/m(2) higher genetically determined BMI the odds ratio for any non-skin cancer was 1.16 (0.64-2.09), with a corresponding observational estimate of 0.94 (0.88-1.01). Using 108,812 individuals from the general population, we found that observationally high BMI was associated with lower risk of lung and skin cancer overall and with higher risk of breast cancer in postmenopausal women, but not with other types of cancer. BMI increasing alleles were not associated with risk of cancer, and results do not support causal associations. Power to test associations for some cancer sites was low.

Long-term prognosis of asthma, chronic obstructive pulmonary disease, and asthma-chronic obstructive pulmonary disease overlap in the Copenhagen City Heart study: a prospective population-based analysis

Long-term prognosis of patients with characteristics of both chronic obstructive pulmonary disease (COPD) and asthma, named asthma-COPD overlap, is poorly described. We investigated the long-term prognosis of individuals with different types of chronic airway disease, with a special focus on individuals with asthma-COPD overlap. We assigned participants from the Copenhagen City Heart Study into six subgroups: healthy never-smokers, ever-smokers without asthma and COPD, those with asthma with low cumulated smoking exposure and no airflow limitation, those with COPD, those with asthma-COPD overlap with asthma onset before the age of 40 years, and those with asthma-COPD overlap with asthma onset after the age of 40 years. We defined asthma-COPD overlap as current self-reported asthma and a postbronchodilatatory forced expiratory volume in 1 s (FEV1) to forced vital capacity ratio of less than 0·7, without any restrictions regarding smoking. We investigated the course of FEV1 decline for 18 years and risk of admission to hospital due to exacerbations or pneumonias and respiratory and all-cause mortality for 22 years. We analysed FEV1 decline in the six groups using a linear mixed-effects model. We included 8382 participants from the Copenhagen City Heart Study in our study: 2199 never-smokers, 5435 ever-smokers, 158 with asthma, 320 with COPD, 68 with asthma-COPD overlap with early-onset asthma, and 202 with asthma-COPD overlap with late-onset asthma. The multivariable-adjusted decline in FEV1 in asthma-COPD overlap with early-onset asthma was 27·3 mL (standard error 5·0) per year, which did not differ significantly from the decline of 20·9 mL (1·2) per year in healthy never-smokers (p=0·19). FEV1 decline in individuals with asthma-COPD overlap with late-onset asthma was 49·6 mL (3·0) per year, higher than the decline in asthma-COPD overlap with early-onset asthma (p=0·0001), the decline of 39·5 mL (2·5) per year in COPD (p=0·003), and the decline in healthy never-smokers (p<0·0001). Hazard ratios for hospital admissions due to exacerbations of asthma or COPD were 39·48 (95% CI 25·93-60·11) in asthma-COPD overlap with early-onset asthma, 83·47 (61·67-112·98) in asthma-COPD overlap with late-onset asthma, 23·80 (17·43-33·50) in COPD, and 14·74 (10·06-21·59) in asthma compared with never-smokers without lung disease (all p<0·0001). Life expectancy was 9·3 years (5·4-13·1) shorter in participants with asthma-COPD overlap with early-onset asthma, 12·8 years (11·1-14·6) shorter in those with asthma-COPD overlap with late-onset asthma, 10·1 years (8·6-11·5) shorter in those with COPD (all p<0·0001), and 3·3 years (1·0-5·5) shorter in those with asthma (p=0·004) than in healthy never-smokers. Prognosis of individuals with asthma-COPD overlap is poor and seems to be affected by the age of recognition of asthma, being worst in those with late asthma onset (after 40 years of age). Such patients should be followed up closely to prevent fast lung function decline and exacerbations. Capital Region of Copenhagen, Danish Heart Foundation, Danish Lung Foundation, Velux Foundation, AstraZeneca.

Morbidity and Mortality in 7,684 Women According to Personal Hair Dye Use: The Copenhagen City Heart Study followed for 37 Years.

BackgroundPermanent hair dye contains aromatic amines which are carcinogenic, and can cause allergic skin reactions. In the long term personal use of hair dye might therefore influence both morbidity and mortality.ObjectivesWe tested the hypothesis that personal use of hair dye in women is associated with increased morbidity and mortality in the general population.MethodsWe included 7,684 women from the Copenhagen City Heart Study with information on the use of personal hair dye. We assessed the risk of cancer, skin diseases, other morbidities, and mortality during a median follow-up of 27 years (range 0–37).ResultsThe multivariable adjusted hazard ratio for malignant melanoma in women with versus without personal use of hair dye was 2.07 (95% confidence interval 1.25–3.42). There was no increased risk of other cancer types. For other skin diseases and other major causes of morbidity we found no differences between the two groups, except for a minor excess of digestive diseases and increased risk of Parkinson’s disease among women using hair dye. Finally, we found no difference in all-cause mortality comparing women using personal hair dye or not. After correction for multiple comparisons, none of the results remained significant. However, in sensitivity analysis the excess risk of malignant melanoma remained increased with a hazard ratio of 2.58 (95%CI 1.33–5.03) among users of personal hair dye.ConclusionsPersonal use of hair dye does not have major influences on morbidity and mortality. Our finding of a 2-fold risk of malignant melanoma in women using hair dye is hypothesis generating.

Does SOD3 R213G Homozygosity Influence Morbidity, Mortality, and Lung Function in the General Population?

The extracellular superoxide dismutase (SOD3, EC-SOD) enzyme is a major extracellular scavenger of the superoxide anion, a free radical with the potential to cause oxidative damage. Previously, R213G heterozygosity has been associated with a decreased risk of chronic obstructive pulmonary disease (COPD) and an increased risk of ischemic heart disease (IHD). We questioned whether SOD3 R213G homozygosity (213GG) influences morbidity, mortality, and lung function. We found 14 R213G homozygotes (213GG) among 95,871 individuals (1/7000) from the Copenhagen General Population Study and the Copenhagen City Heart Study. The hazard ratio for homozygotes versus noncarriers (NC) (213RR) was 2.8 (95% confidence interval: 1.2-6.8, p = 0.02) for IHD, 1.8 (0.7-4.8, p = 0.25) for any form of cancer, and 2.3 (0.9-6.2, p = 0.10) for all-cause mortality. R213G heterozygosity was not associated with morbidity or mortality. Among never-smokers, we found a 20% lower forced expiratory volume in 1 s (FEV1)% predicted (p = 0.003), a 16% lower FVC% predicted (p = 0.01), and a 7% lower FEV1/FVC ratio (p = 0.02) in R213G homozygotes compared to NC. Our results lead to the hypotheses that the SOD3 enzyme plays a role in cardiovascular disease and in impairing and maintaining lung function in never-smokers. However, our findings should be retested in larger studies and in nonsmoking COPD patient cohorts. Antioxid. Redox Signal. 24, 884-891.

Data on plasma levels of apolipoprotein E, correlations with lipids and lipoproteins stratified by APOE genotype, and risk of ischemic heart disease.

Data on correlations of plasma apoE with levels of lipids and lipoproteins stratified by APOE genotypes as well as data exploring the association between plasma levels of apoE and risk of ischemic heart disease (IHD) are wanted.The present data on 91,695 individuals from the general population provides correlations between plasma levels of apoE and lipids and lipoproteins for the three APOE genotypes ε33, ε44 and ε22, representing each of the three apoE isoforms. Further, data on extreme groups of plasma apoE (highest 5%) versus lower levels of apoE at enrollment explores risk of IHD and myocardial infarction (MI) and is given as hazard ratios. In addition, IHD and MI as a function of apoE/high-density lipoprotein (HDL) cholesterol ratio, as well as data on lipids, lipoproteins and apolipoproteins are given as hazard ratios. Data is stratified by gender and presented for the Copenhagen General Population Study and the Copenhagen City Heart Study combined.

Elevated Lipoprotein(a) Levels, LPA Risk Genotypes, and Increased Risk of Heart Failure in the General Population

ObjectivesThis study sough to test whether elevated lipoprotein(a) levels and corresponding LPA risk genotypes (low number of kringle IV type 2 repeats, rs3798220 and rs10455872, minor allele carriers) are associated with an increased risk of heart failure (HF). BackgroundElevated lipoprotein(a) levels represent a genetically determined risk factor for myocardial infarction (MI) and aortic valve stenosis (AVS). It is presently unknown whether elevated lipoprotein(a) levels also cause heart failure (HF). MethodsWe combined 2 general population studies, the Copenhagen City Heart Study (n = 10,855) and the Copenhagen General Population Study (n = 87,242), which totaled 98,097 Danish participants, of whom 4,122 were diagnosed with HF (1976 to 2013). We conducted observational and genetic instrumental variable analyses in a Mendelian randomization study design, assessing evidence of causality, and we performed mediation analyses. ResultsElevated lipoprotein(a) levels were associated with multivariable adjusted hazard ratios for HF of 1.10 (95% CI: 0.97 to 1.25) for the 34th to 66th percentiles (8 to 19 mg/dl), 1.24 (95% CI: 1.08 to 1.42) for the 67th to 90th percentiles (20 to 67 mg/dl), 1.57 (95% CI: 1.32 to 1.87) for the 91st to 99th percentiles (68 to 153 mg/dl), and 1.79 (95% CI: 1.18 to 2.73) for levels >99th percentile (>153 mg/dl) versus levels <34th percentile (<8 mg/dl) (trend, p < 0.001), corresponding to a population-attributable risk of 9%. By combining all LPA risk genotypes, instrumental variable analysis yielded a genetic relative risk for HF of 1.18 (95% CI: 1.04 to 1.34) per 10-fold higher lipoprotein(a) levels, which was comparable to the corresponding observational hazard ratio of 1.22 (95% CI: 1.11 to 1.35). Upon exclusion of participants diagnosed with MI or AVS, risk estimates were attenuated. Accordingly, 63% (95% CI: 45% to 99%) of HF risk was mediated via MI and AVS combined. ConclusionsElevated lipoprotein(a) levels and corresponding LPA risk genotypes were associated with an increased risk of HF consistent with a causal association. The association appeared to be partly mediated by MI and AVS.

Genetic Susceptibility to Oxidative Stress and Cardiovascular Disease

Cardiovascular disease continues to be the leading cause of death in patients with Type-2 Diabetes Mellitus (T2D). Aggressive use of HMG-CoA Reductase Inhibitors (statins) and blood pressure lowering agents are showing signs of success as rates of coronary heart disease are on the decline (Ali et al., 2013); however, a substantial amount of residual risk remains suggesting that additional prevention strategies are needed particularly in light of recent increases in the prevalence of T2D (Gregg et al., 2007). Treatments that block the damaging effects of oxidants have long been considered as potential strategies to reduce the risk of cardiovascular disease. Because redox signaling in the heart and other tissues can have both physiological and pathological effects (Burgoyne et al., 2012) any benefit from anti-oxidant therapies may be limited. Indeed, while Vitamin E showed benefit in a mouse atherosclerosis model (Pratico et al., 1998) and observational studies showed an inverse association of Vitamin E intake and cardiovascular disease (Jha et al., 1995), randomized double blind placebo controlled trials do not support a benefit from Vitamin E, and even suggested harm (Lonn et al., 2005). The discordant results of anti-oxidant clinical trials compared with observational and experimental studies raise many considerations including whether clinical trials testing anti-oxidant compounds should target enrollment of subjects that have increased oxidant stress (Robinson et al., 2006). In this issue of EBioMedicine, Kobylecki et al. contribute to our understanding of the role of the natural anti-oxidant system plays in cardiovascular disease through their analysis of the Copenhagen General Population Study and the Copenhagen City Heart Study (Kobylecki et al., 2015). The authors studied a single nucleotide polymorphism in the extracellular superoxide dismutase-3 gene (SOD3) that results in the exchange of an amino acid causing the SOD3 peptide to not be retained in the blood vessel wall. Diabetic individuals heterozygous for this SOD3 variant were found to have an increased risk of cardiovascular disease while strikingly there was no signal in subjects without diabetes. These findings, supported by independent studies (Mohammedi et al., 2015), suggest that some individuals have a genetically-driven impairment of anti-oxidant defenses that predispose them to cardiovascular disease in states of oxidant stress such as diabetes. What is currently unknown is whether restoring anti-oxidant defenses in people that carry the SOD3 polymorphism abrogates the additional risk of cardiovascular disease. Two points should be emphasized. First, despite the negative findings of previous randomized clinical trials this study and others like it should motivate the continued development and testing of novel anti-oxidant compounds to prevent cardiovascular disease, particularly in genetically susceptible individuals that have T2D. Second, genetic studies continue to identify meaningful insight into disease pathogenesis when results from animal and clinical studies conflict. We are on the verge of realizing the benefits of Precision Medicine in cancer therapy through the use of genetic information to guide treatment selection (Collins and Varmus, 2015). While the current use of genetics to guide the prevention of cardiovascular disease is in its infancy, clinical trials that focus on genetically at risk individuals may have the strongest ability to demonstrate a proof-of-principle for the potential benefits of novel treatments.

Genetically Low Antioxidant Protection and Risk of Cardiovascular Disease and Heart Failure in Diabetic Subjects

BackgroundHyperglycemia-induced oxidative stress is one mechanism believed to underlie diabetic vascular disease. We tested the hypothesis that diabetic subjects heterozygous for extracellular superoxide dismutase (SOD3) R213G, which entails lower antioxidant capacity in tissues, have increased risk of cardiovascular disease and heart failure. MethodsWe used the prospective Copenhagen General Population Study and Copenhagen City Heart Study and genotyped 95,871 individuals for the rs1799895 R213G variation in the SOD3 gene, of which 4498 had diabetes. We used national hospitalization and death registers to assess cardiovascular disease and heart failure. FindingsOut of 95,871 individuals, we identified 93,521 R213G non-carriers (213RR, 97.5%), 2336 heterozygotes (213RG, 2.4%) and 14 homozygotes (213GG, 0.01%). In diabetic subjects, the hazard ratio for cardiovascular disease in R213G heterozygotes compared to non-carriers was 2.32 (95% CI 1·44–3.75), with a corresponding hazard ratio in non-diabetic subjects of 0.97 (0·80–1.19) (p for interaction 0.002). For heart failure, the hazard ratios in R213G heterozygotes compared to non-carriers were 2.19 (1.28–3.76) in diabetic and 0.68 (0.49–0.92) in non-diabetic subjects (p for interaction<0.001). InterpretationRisk of cardiovascular disease and heart failure was higher in R213G heterozygotes versus non-carriers in diabetic subjects, but not in non-diabetic subjects.

Abstract 19109: Low PCSK9 and LDL Cholesterol and Risk of Dementia, Parkinson’s Disease, and Epilepsy - A Mendelian Randomization Study

Introduction: Low levels of low-density-lipoprotein cholesterol(LDL-C) due to statin use has been associated with reduced cognitive function. We aimed to assess whether low LDL-C due to genetic variation in the 3-hydroxy-3-methylglutaryl-CoA reductase(HMGCR; rs17238484) and proprotein convertase subtilisin kexin 9(PCSK9; rs11591147, rs148195424, rs562556, rs505151) genes, involved in LDL-C biosynthesis and metabolism, respectively, is associated with risk of Alzheimer’s dementia, vascular dementia, all dementia, Parkinson’s disease, and epilepsy in a general population off and on lipid lowering medication. Methods: We examined associations of plasma LDL-C with observational risk of disease; genetic variants with plasma LDL-C levels; and genetic variants and risk of disease as an indication of causality using a Mendelian randomization design in 92,068 participants off and 11,519 participants on lipid lowering medication from the Copenhagen General Population Study and the Copenhagen City Heart Study. Results: In observational analysis, risk of epilepsy was 98%(95% confidence interval: 32%-297%) higher in participants with an LDL-C &lt;1.5mmol/L versus ≥3.0mmol/L. Low LDL-C was not associated with risk of Alzheimer’s dementia, vascular dementia, all dementia, and Parkinson’s disease. In causal genetic analyses, PCSK9 and HMGCR variants associated with 7.8% and 2.9% lower LDL-C. Genotypes were not associated with risk of Alzheimer’s dementia, vascular dementia, all dementia, Parkinson’s disease, or epilepsy. Conclusions: Using 103,587 individuals from the general population, we found that observationally low LDL-C level was associated with increased risk of epilepsy. Low LDL-C due to PCSK9 and HMGCR variants was not associated with Alzheimer’s dementia, vascular dementia, all dementia, Parkinson’s disease or epilepsy, and results does not support a causal role of low LDL-C in these diseases.

Abstract 16954: SCARB1 Gene Variants are Associated With the New Lipid Phenotype of Combined High HDL-C and Lp(a)

Introduction: Although lipoprotein(a) (Lp(a)) is atherogenic, little is known about how it is transported from the plasma. Scavenger receptor class B type 1 (SR-B1), encoded by the gene SCARB1, binds high density lipoproteins (HDL). Recently we found that SR-B1 is also a receptor for Lp(a), mediates cellular uptake of Lp(a) in vitro, and promotes clearance of Lp(a) in vivo in mice. Genetic variants in SCARB1 have been associated with HDL level in humans, but no SCARB1 variants affecting Lp(a) have been reported. We hypothesized that loss of function mutations in SCARB1 would be associated with a phenotype of combined high HDL-C and Lp(a). Methods and Results: An index subject was identified in the NIH Lipid Clinic with high levels of both HDL-C and Lp(a). SCARB1 was sequenced and demonstrated a missense mutation at c.386 resulting in an S129L substitution in exon 3. To follow up on this finding, two cohorts of subjects (n=543 in the Genetic Study of Atherosclerosis Risk (GeneSTAR) and n=5907 in the Copenhagen City Heart Study) were screened for combined elevations of HDL-C and Lp(a). Subjects having HDL &gt;80 mg/dl and Lp(a) &gt;100 nmol/L in GeneSTAR, n=8, and &gt;100 mg/dl in CCHS, n=9, underwent sequencing of all SCARB1 exons and splice junctions; 15 from the combined population of 18 were found to have variants predicted or demonstrated to have reduced function of the translated protein. Functional studies showed that 4 of the SCARB1 variants (c.386C&gt;T; c.631-14T&gt;G, c.4G&gt;A and c.631-53mC&gt;T &amp; c.726+55mCG&gt;CA, all heterozygous) had decreased receptor function in vitro, and the latter two were novel and not previously reported. Six of the subjects were homozygous for a common synonymous SCARB1 polymorphism (c.1050C&gt;T) which has been reported to be associated with reduced protein expression. Conclusion: Human SCARB1 gene variants are associated with a new lipid phenotype, characterized by increases in both HDL-C and Lp(a). We demonstrate that SCARB1 exonic variants often result in diminished function of the translated SR-B1 lipid receptor with reduced binding/intracellular transport of Lp(a).