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The genetic contributions to early onset heart failure (HF) are incompletely understood. Genetic testing in advanced HF patients undergoing heart transplantation (HTx) may yield clinical benefits, but data is limited. We performed deep-coverage whole genome sequencing (WGS) in 102 Swedish HTx recipients. Gene lists were compiled through a systematic literature review. Variants were prioritized for pathogenicity and classified manually. We also compared polygenic HF risk scores to a population-based cohort. We found a pathogenic (LP/P) variant in 34 individuals (34%). Testing yield was highest in hypertrophic (63% LP/P carriers), dilated (40%) and arrhythmogenic right ventricular (33%) cardiomyopathy and lower in ischemic cardiomyopathy (10%). A family history was more common in LP/P variant carriers than in non-carriers but was present in less than half of carriers (44% vs 13%, P < 0.001), whereas age was similar. Polygenic risk scores were similar in HTx recipients and the population cohort. In conclusion, we observed a high prevalence of pathogenic cardiomyopathy gene variants in individuals with early-onset advanced HF, which could not accurately be ruled out by family history and age. In contrast, we did not observe higher polygenic risk scores in early onset advanced HF cases than in the general population. [ABSTRACT FROM AUTHOR]

Plasma metabolomics holds potential for precision medicine, but limited information is available to compare the performance of such methods across multiple cohorts. We compared plasma metabolite profiles after an overnight fast in 11,309 participants of five population-based Swedish cohorts (50–80 years, 52% women). Metabolite profiles were uniformly generated at a core laboratory (Metabolon Inc.) with untargeted liquid chromatography mass spectrometry and a comprehensive reference library. Analysis of a second sample obtained one year later was conducted in a subset. Of 1629 detected metabolites, 1074 (66%) were detected in all cohorts while only 10% were unique to one cohort, most of which were xenobiotics or uncharacterized. The major classes were lipids (28%), xenobiotics (22%), amino acids (14%), and uncharacterized (19%). The most abundant plasma metabolome components were the major dietary fatty acids and amino acids, glucose, lactate and creatinine. Most metabolites displayed a log-normal distribution. Temporal variability was generally similar to clinical chemistry analytes but more pronounced for xenobiotics. Extensive metabolite-metabolite correlations were observed but mainly restricted to within each class. Metabolites were broadly associated with clinical factors, particularly body mass index, sex and renal function. Collectively, our findings inform the conduct and interpretation of metabolite association and precision medicine studies. [ABSTRACT FROM AUTHOR]

Whereas autonomic dysfunction and the metabolic syndrome are clinically associated, the relationships with the plasma metabolome is unknown. We explored the association between orthostatic blood pressure responses and 818 plasma metabolites in middle-aged subjects from the general population. We included 3803 out of 6251 subjects (mean age, 57 years; 52% women) from the Malmö sub-cohort of The Swedish CardioPulmonary bioImage Study with information on smoking habits, diabetes, antihypertensive drug treatment, anthropometrics, hemodynamic measurements and 818 plasma metabolites (mass-spectrometry). The associations between each metabolite and orthostatic systolic blood pressure responses were determined using multivariable linear regression analysis and p values were corrected using the Bonferroni method. Six amino acids, five vitamins, co-factors and carbohydrates, nine lipids and two xenobiotics were associated with orthostatic blood pressure after adjusting for age, gender and systolic blood pressure. After additional adjustments for BMI, diabetes, smoking and antihypertensive treatment, the association remained significant for six lipids, four amino acids and one xenobiotic. Twenty-two out of 818 plasma metabolites were associated with orthostatic blood pressure responses. Eleven metabolites, including lipids in the dihydrosphingomyelin and sphingosine pathways, were independently associated with orthostatic systolic blood pressure responses after additional adjustment for markers of cardio-metabolic disease. [ABSTRACT FROM AUTHOR]

Resting heart rate is associated with cardiovascular diseases and mortality in observational and Mendelian randomization studies. The aims of this study are to extend the number of resting heart rate associated genetic variants and to obtain further insights in resting heart rate biology and its clinical consequences. A genome-wide meta-analysis of 100 studies in up to 835,465 individuals reveals 493 independent genetic variants in 352 loci, including 68 genetic variants outside previously identified resting heart rate associated loci. We prioritize 670 genes and in silico annotations point to their enrichment in cardiomyocytes and provide insights in their ECG signature. Two-sample Mendelian randomization analyses indicate that higher genetically predicted resting heart rate increases risk of dilated cardiomyopathy, but decreases risk of developing atrial fibrillation, ischemic stroke, and cardio-embolic stroke. We do not find evidence for a linear or non-linear genetic association between resting heart rate and all-cause mortality in contrast to our previous Mendelian randomization study. Systematic alteration of key differences between the current and previous Mendelian randomization study indicates that the most likely cause of the discrepancy between these studies arises from false positive findings in previous one-sample MR analyses caused by weak-instrument bias at lower P-value thresholds. The results extend our understanding of resting heart rate biology and give additional insights in its role in cardiovascular disease development. The genetics and clinical consequences of resting heart rate (RHR) remain incompletely understood. Here, the authors discover new genetic variants associated with RHR and find that higher genetically predicted RHR decreases risk of atrial fibrillation and ischemic stroke. [ABSTRACT FROM AUTHOR]

Human gut microbiota produce a variety of molecules, some of which enter the bloodstream and impact health. Conversely, dietary or pharmacological compounds may affect the microbiota before entering the circulation. Characterization of these interactions is an important step towards understanding the effects of the gut microbiota on health. In this cross-sectional study, we used deep metagenomic sequencing and ultra-high-performance liquid chromatography linked to mass spectrometry for a detailed characterization of the gut microbiota and plasma metabolome, respectively, of 8583 participants invited at age 50 to 64 from the population-based Swedish CArdioPulmonary bioImage Study. Here, we find that the gut microbiota explain up to 58% of the variance of individual plasma metabolites and we present 997 associations between alpha diversity and plasma metabolites and 546,819 associations between specific gut metagenomic species and plasma metabolites in an online atlas (https://gutsyatlas.serve.scilifelab.se/). We exemplify the potential of this resource by presenting novel associations between dietary factors and oral medication with the gut microbiome, and microbial species strongly associated with the uremic toxin p-cresol sulfate. This resource can be used as the basis for targeted studies of perturbation of specific metabolites and for identification of candidate plasma biomarkers of gut microbiota composition. Here, Dekkers et al. characterize associations of 1528 gut metagenomic species with the plasma metabolome in 8583 participants of the SCAPIS Study, and find that gut microbiota explain up to 58% of the variance of individual plasma metabolites. [ABSTRACT FROM AUTHOR]

Hemodynamic force analysis has been proposed as a novel tool for early detection of subclinical systolic dysfunction in heart failure with preserved ejection fraction (HFpEF). Here we investigated the ability of hemodynamic forces to discriminate between healthy subjects and heart failure patients with varying degrees of systolic dysfunction. We studied 34 controls, 16 HFpEF patients, and 25 heart failure patients with mid-range (HFmrEF) or reduced ejection fraction (HFrEF) using cardiac magnetic resonance with acquisition of cine images and 4D flow at 1.5 T. The Navier–Stokes equation was used to compute global left ventricular hemodynamic forces over the entire cardiac cycle. Forces were analyzed for systole, diastole, and the entire heartbeat, with and without normalization to left ventricular volume. Volume-normalized hemodynamic forces demonstrated significant positive correlation with EF (r2 = 0.47, p < 0.0001) and were found significantly lower in heart failure with reduced ejection fraction compared to controls (p < 0.0001 for systole and diastole). No difference was seen between controls and HFpEF (p > 0.34). Non-normalized forces displayed no differences between controls and HFpEF (p > 0.24 for all analyses) and did not correlate with EF (p = 0.36). Left ventricular hemodynamic force analysis, whether indexed to LV volumes or not, is not ready for clinical trials on HFpEF assessment. [ABSTRACT FROM AUTHOR]

The electrocardiographic PR interval reflects atrioventricular conduction, and is associated with conduction abnormalities, pacemaker implantation, atrial fibrillation (AF), and cardiovascular mortality. Here we report a multi-ancestry (N = 293,051) genome-wide association meta-analysis for the PR interval, discovering 202 loci of which 141 have not previously been reported. Variants at identified loci increase the percentage of heritability explained, from 33.5% to 62.6%. We observe enrichment for cardiac muscle developmental/contractile and cytoskeletal genes, highlighting key regulation processes for atrioventricular conduction. Additionally, 8 loci not previously reported harbor genes underlying inherited arrhythmic syndromes and/or cardiomyopathies suggesting a role for these genes in cardiovascular pathology in the general population. We show that polygenic predisposition to PR interval duration is an endophenotype for cardiovascular disease, including distal conduction disease, AF, and atrioventricular pre-excitation. These findings advance our understanding of the polygenic basis of cardiac conduction, and the genetic relationship between PR interval duration and cardiovascular disease. On the electrocardiogram, the PR interval reflects conduction from the atria to ventricles and also serves as risk indicator of cardiovascular morbidity and mortality. Here, the authors perform genome-wide meta-analyses for PR interval in multiple ancestries and identify 141 previously unreported genetic loci. [ABSTRACT FROM AUTHOR]

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. A small proportion of HF cases are attributable to monogenic cardiomyopathies and existing genome-wide association studies (GWAS) have yielded only limited insights, leaving the observed heritability of HF largely unexplained. We report results from a GWAS meta-analysis of HF comprising 47,309 cases and 930,014 controls. Twelve independent variants at 11 genomic loci are associated with HF, all of which demonstrate one or more associations with coronary artery disease (CAD), atrial fibrillation, or reduced left ventricular function, suggesting shared genetic aetiology. Functional analysis of non-CAD-associated loci implicate genes involved in cardiac development (MYOZ1, SYNPO2L), protein homoeostasis (BAG3), and cellular senescence (CDKN1A). Mendelian randomisation analysis supports causal roles for several HF risk factors, and demonstrates CAD-independent effects for atrial fibrillation, body mass index, and hypertension. These findings extend our knowledge of the pathways underlying HF and may inform new therapeutic strategies. Heart failure is a complex syndrome that is associated with many different underlying risk factors. Here, to increase power, the authors jointly analyse cases of heart failure of different aetiologies in a genome-wide association study and identify 11 loci of which ten had not been previously reported. [ABSTRACT FROM AUTHOR]

Heart failure (HF) is a major public health problem characterized by inability of the heart to maintain sufficient output of blood. The systematic characterization of circulating proteins across different stages of HF may provide pathophysiological insights and identify therapeutic targets. Here we report application of aptamer-based proteomics to identify proteins associated with prospective HF incidence in a population-based cohort, implicating modulation of immunological, complement, coagulation, natriuretic and matrix remodeling pathways up to two decades prior to overt disease onset. We observe further divergence of these proteins from the general population in advanced HF, and regression after heart transplantation. By leveraging coronary sinus samples and transcriptomic tools, we describe likely cardiac and specific cellular origins for several of the proteins, including Nt-proBNP, thrombospondin-2, interleukin-18 receptor, gelsolin, and activated C5. Our findings provide a broad perspective on both cardiac and systemic factors associated with HF development. Heart failure is a major health issue worldwide. Here, Egerstedt et al. perform proteomic profiling of human plasma at different stages of heart failure, providing a comprehensive analysis of changes in the plasma proteome during disease progression. [ABSTRACT FROM AUTHOR]

The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD. [ABSTRACT FROM AUTHOR]

Low hemoglobin concentration is associated with increased mortality, but there is disagreement with regard to the clinical definition of anemia. We aimed to evaluate the prevalence, clinical correlates and association with total and cause-specific long-term mortality across the hemoglobin distribution and for previously proposed definitions of anemia. Blood hemoglobin concentration and mean corpuscular volume was measured in participants of the Malmö diet and cancer study-a prospective cohort study, and related to baseline characteristics and outcomes during follow-up. Primary endpoints were all-cause mortality, cardiovascular mortality and cancer-related mortality. A U-shaped association of hemoglobin with total mortality was observed in spline regression analyses, with nadir at hemoglobin 150 g/L among men and 130 g/L among women. Mortality increased steeply with more strict definitions of anemia, hazard ratio: 1.36, 1.94 and 2.16 for hemoglobin <140/130 (men/women), 132/122 and 130/120 g/L, respectively. Similar trends were seen for both cancer- and cardiovascular mortality. The incidence of coronary disease and cancer did not differ across groups. Erythrocyte volume was an independent predictor of mortality, with the highest mortality observed for macrocytic anemia, which was less prevalent than microcytic and normocytic anemia. Dietary intake of iron and vitamin B12 were significantly lower and use of antithrombotic medications was significantly higher in subjects with anemia. The World Health Organisation definition of anemia was associated with increased mortality (hazard ratio 2.16) but excess mortality was also observed at higher hemoglobin levels. Of morphological subtypes, anemia with macrocytosis was rare but associated with the highest mortality. [ABSTRACT FROM AUTHOR]

Although stroke remains a leading cause of disability and mortality worldwide, recently there have been significant advances related to our understanding of the genetic basis of stroke. Ongoing research efforts put us on the cusp for major breakthroughs in the field. In this review, we present the substantial evidence for the contribution of genetic variation to the development of stroke, and the difficulties posed in the study of stroke given the numerous genetically driven risk factors and stroke subtypes. We emphasize recent findings implementing candidate gene and genome-wide association approaches. We then discuss how emerging knowledge is informing and reshaping our understanding of stroke biology and how, in the near term, genetics may be used clinically to identify individuals who are at risk of disease or who may derive benefit from specific treatment modalities. Lastly, we address ongoing and future approaches that will continue to improve our understanding of stroke genetics. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases are among the leading causes of morbidity and mortality in the developed world despite advances in cardiac care over the last few decades. Although most of these advances in cardiovascular medicine have been made through trials of therapies on a population scale, the success of such therapies in a patient often is dependent on particular aspects of each individual. In this review, we present the evidence for the impact that the use of personalized medicine and genetics can have in the cardiac care of a patient, first through risk stratification based on inherent genetic risk inferred from the results of genome-wide association studies, to the use of pharmacogenomics to guide clinical management. Finally, we discuss the coming flood of human genome sequencing and the potential impact it will have on the care of patients from the standpoint of cardiovascular disease. [ABSTRACT FROM AUTHOR]

Thrombophilia has been subject to extensive genetic research. This review focuses on the genetic variants that have confirmed associations with venous thrombosis (VT). For incident VT, the early discovery of variants with large-magnitude associations, such as mutations in antithrombin, protein C, and protein S genes, has been followed by genetic variants that are associated with more moderate risk, such as the factor V Leiden, and prothrombin G20210A. More recently, large candidate-gene and genome-wide association studies have discovered multiple genetic variants with generally weak association with VT. For recurrent VT, the evidence for genetic risk factors remains very limited. Although thrombophilia testing is broadly available to clinicians, the impact on the clinical management of patients remains modest and depends on the strength of the association with VT. More promising for clinical practice may be global assessments of risk that combine risk information from multiple genetic variants, or with those from acquired risk factors. These models have yet to be defined and tested in large and diverse populations to demonstrate that this new genetic risk information has clinical applicability and improves health outcomes. [ABSTRACT FROM AUTHOR]

Low-grade inflammation has been repeatedly associated with cardiovascular diseases but the relationship with incidence of atrial fibrillation (AF) remains unclear. We explored the association between elevated plasma levels of inflammation-sensitive proteins (ISPs) and incidence of AF in a population-based cohort. Plasma levels of five ISPs (fibrinogen, haptoglobin, ceruloplasmin, α-antitrypsin and orosomucoid) and two complement factors (C3 and C4) were measured in 6,031 men (mean age 46.8 years) without history of myocardial infarction, heart failure, stroke or cancer. Incidence of hospitalizations due to AF during a mean follow-up of 25 years was studied both in relation to individual inflammatory proteins and the number of elevated ISPs. During follow-up, 667 patients were hospitalized with a diagnosis of AF. After adjustment for potential confounding factors, the hazard ratios (HR) for AF were 1.00 (reference), 1.08 (95% CI: 0.88-1.31), 1.07 (CI: 0.84-1.36), and 1.40 (CI: 1.12-1.74), respectively, in men with none, one, two and three or more ISPs in the 4th quartile ( P for trend = 0.007). Ceruloplasmin was the only individual ISP significantly associated with incidence of AF after adjustment for confounding factors (HR 1.17 per standard deviation, 95% CI: 1.08-1.26). In conclusion, a score of five ISPs was associated with long-term incidence of hospitalizations due to AF in middle-aged men. Of the individual ISPs, a significant association was observed for ceruloplasmin, a protein previously associated with copper metabolism and oxidative stress. [ABSTRACT FROM AUTHOR]

The validity of atrial fibrillation (AF) diagnoses in national registers for use as endpoints in prospective studies has not been evaluated. We studied the validity of AF diagnoses in Swedish national hospital discharge and cause of death registers and the occurrence of and risk factors for AF in a middle-aged Swedish population using these registers. Our study included the 30,447 individuals (age 44–73) who attended baseline visits in 1991–1996 of the Malmö Diet and Cancer study. Individuals with a first AF diagnosis were identified by record linkage with national registers. A subset of cases was randomly selected for validation by examination of electrocardiograms and patient records. Electrocardiograms were available in 98% of the validation sample (95% definitive AF, 3% no AF). The 2% with ECGs unavailable had probable AF. Baseline AF prevalence was 1.3%, higher in men and increased with age. During 11.2 years of follow-up 1430 first AF diagnoses occurred. Risk factors were age, hypertension, BMI, diabetes, history of heart failure, history of myocardial infarction and, in men but not women, current smoking. The strongest risk factors were history of heart failure (hazard ratio men 4.5, women 8.7) and myocardial infarction (hazard ratio men 2.0, women 1.8). The largest population attributable risks were observed for hypertension (men 38%, women 34%) and obesity (men 11%, women 10%). In conclusion, case misclassification of AF in national registers is small, indicating feasibility of use in prospective studies. Hypertension and obesity account for large portions of population risk in middle-aged individuals with low prevalence of manifest cardiac disease. [ABSTRACT FROM AUTHOR]

Plasma concentrations of many cardiovascular and inflammatory proteins are altered after ST-elevation myocardial infarction (STEMI) and may provide prognostic information. We conducted a large-scale proteomic analysis in patients with STEMI, correlating protein levels to infarct size and left ventricular ejection fraction (LVEF) determined with cardiac magnetic resonance imaging. We analysed 131 cardiovascular and inflammatory proteins using a multiplex proximity extension assay and blood samples obtained at baseline, 6, 24, and 96 h from the randomised clinical trial CHILL-MI. Cardiac magnetic resonance imaging data at 4 ± 2 days and 6 months were available as per trial protocol. Using a linear regression model with bootstrap resampling and false discovery rate adjustment we identified five proteins (ST2, interleukin-6, pentraxin-3, interleukin-10, renin, and myoglobin) with elevated values corresponding to larger infarct size or worse LVEF and four proteins (TNF-related apoptosis-inducing ligand, TNF-related activation induced cytokine, interleukin-16, and cystatin B) with values inversely related to LVEF and infarct size, concluding that among 131 circulating inflammatory and cardiovascular proteins in the acute and sub-acute phase of STEMI, nine showed a relationship with infarct size and LVEF post-STEMI, with IL-6 and ST2 exhibiting the strongest association. [ABSTRACT FROM AUTHOR]