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Background Physical inactivity and low cardiorespiratory fitness (CRF) are associated with higher risk of heart failure. However, the independent contributions of objectively measured sedentary time, physical activity, and CRF toward left ventricular (LV) structure and function are not well established. Methods and Results We included 1368 participants from the DHS (Dallas Heart Study) (age, 49 years; 40% men) free of cardiovascular disease who had physical activity and sedentary time measured by accelerometer, CRF estimated from submaximal treadmill test, and cardiac magnetic resonance imaging performed using 3-T magnetic resonance imaging. A series of linear regression models were constructed to evaluate the associations of sedentary time, moderate physical activity, vigorous physical activity, and CRF with LV parameters after adjustment for established cardiovascular risk factors. We observed a modest correlation between CRF levels and objectively measured moderate (correlation coefficient, 0.17; P <0.001) and vigorous physical activity (correlation coefficient, 0.25; P <0.001) levels. In contrast, sedentary time was not associated with CRF. In adjusted analysis, both vigorous physical activity and higher CRF were significantly associated with greater stroke volume, LV mass, LV end-diastolic volume, and lower arterial elastance, independent of other confounders. Sedentary time and moderate physical activity levels were not associated with LV parameters. Conclusions Vigorous physical activity and CRF are significantly associated with cardiac structure and function parameters. Future studies are needed to determine if interventions aimed at improving CRF levels may favorably modify cardiac structure and function.

Importance: Compared with white individuals, black individuals have increased electrocardiographic voltage and an increased prevalence of concentric left ventricular (LV) hypertrophy. Whether environmental or genetic factors lead to these racial differences is unknown., Objective: To determine whether proportion of genetically determined African ancestry among self-reported black individuals is associated with increased electrocardiographic voltage and concentric LV hypertrophy (LVH)., Design, Setting, and Participants: The Dallas Heart Study is a probability-based cohort study of English- or Spanish-speaking Dallas County, Texas, residents, with deliberate oversampling of black individuals. Participants underwent extensive phenotyping, which included electrocardiography (ECG), cardiac magnetic resonance imaging (CMR), and dual-energy radiography absorptiometry (DEXA) at a single center. Participants aged 18 to 65 years who enrolled in the Dallas Heart Study between July 2000 and December 2002, self-identified as black (n = 1251) or white (n = 826), and had ECG, CMR, and DEXA data were included in this analysis. Data were analyzed from June 2017 to September 2018., Exposures: Proportion of African ancestry., Main Outcomes and Measures: Electrocardiographic voltage (12-lead and 9-lead) and markers of concentric LVH as assessed by CMR (LV concentricity0.67 [LV mass/end-diastolic volume0.67], LV wall thickness [LVWT], and prevalent LVH [defined by LV mass/height2.7])., Results: Of the 2077 participants included in the study, 1138 (54.8%) were women, and the mean (SD) age was 45.2 (9.9) years. Black race and African ancestry were individually associated with increased ECG voltage, LV concentricity0.67, LVWT, and prevalent LVH in multivariable analyses adjusting for age, sex, systolic blood pressure, antihypertensive medication use, and body composition. When African ancestry and black race were entered together into multivariable models, African ancestry but not black race remained associated with ECG voltage, LVWT, LV concentricity0.67, and prevalent LVH. Among black participants, African ancestry remained associated with these 4 phenotypes (12-lead voltage: β, 0.05; P = .04; LVWT: β, 0.05; P = .02; LV concentricty0.67: β, 0.05; P = .045; prevalent LVH: odds ratio, 1.2; 95% CI, 1.03-1.4; P = .02)., Conclusions and Relevance: Genetically determined African ancestry was associated with electrocardiographic voltage, measures of concentric LV remodeling, and prevalent LVH. These data support a genetic basis related to African ancestry for the increased prevalence of these cardiovascular traits in black individuals.

Aims: Prior cohorts demonstrating the importance of serum chloride levels in heart failure either excluded or had partial representation of patients with heart failure with preserved ejection fraction (HFpEF). We aimed to examine the relationship between serum chloride concentration and outcomes in HFpEF., Methods and Results: We included participants from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist Trial (TOPCAT) who met the following criteria: met inclusion by the natriuretic peptide stratum, had recorded serum chloride levels, and were from the Americas (n = 942). Multivariable Cox proportional hazards models tested the association of serum chloride with clinical outcomes, and mixed effects modelling tested the association of spironolactone or loop diuretic on serial serum chloride levels. The median serum chloride level was 102 [25th-75th percentile 100-105 mmol/L (range 84-114 mmol/L)]. After multivariable adjustment, every standard deviation decrease in serum chloride (4.05 mmol/L) was associated with ∼50% increased risk for cardiovascular death [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.11-2.06, P = 0.008] and ∼30% increased risk for all-cause death (HR 1.29, 95% CI 1.02-1.62, P = 0.04), but not with the primary composite endpoint or heart failure hospitalization (P > 0.3 for both). There were no significant interactions between spironolactone use and the serum chloride-risk relationship (P > 0.1) for each endpoint. Spironolactone was not (P = 0.33) but loop diuretic use was associated with lower serial serum chloride levels (P < 0.001)., Conclusion: Lower serum chloride was independently associated with increased risk of cardiovascular and all-cause death in HFpEF. Loop diuretic use, but not spironolactone, lead to a decrease in serum chloride levels over time., (© 2018 The Authors. European Journal of Heart Failure © 2018 European Society of Cardiology.)

Background: In the conventional paradigm of the progression of left ventricular hypertrophy, a thick-walled left ventricle (LV) ultimately transitions to a dilated cardiomyopathy. There are scant data in humans demonstrating whether this transition occurs commonly without an interval myocardial infarction., Methods and Results: Participants (n=1282) from the Dallas Heart Study underwent serial cardiac magnetic resonance ≈7 years apart. Those with interval cardiovascular events and a dilated LV (increased LV end-diastolic volume [EDV] indexed to body surface area) at baseline were excluded. Multivariable linear regression models tested the association of concentric hypertrophy (increased LV mass and LV mass/volume 0.67 ) with change in LVEDV. The study cohort had a median age of 44 years, 57% women, 43% black, and 11% (n=142) baseline concentric hypertrophy. The change in LVEDV in those with versus without concentric hypertrophy was 1 mL (-9 to 12) versus -2 mL (-11 to 7), respectively, P <0.01. In multivariable linear regression models, concentric hypertrophy was associated with larger follow-up LVEDV ( P ≤0.01). The progression to a dilated LV was uncommon (2%, n=25)., Conclusions: In the absence of interval myocardial infarction, concentric hypertrophy was associated with a small, but significantly greater, increase in LVEDV after 7-year follow-up. However, the degree of LV enlargement was minimal, and few participants developed a dilated LV. These data suggest that if concentric hypertrophy does progress to a dilated cardiomyopathy, such a transition would occur over a much longer timeframe (eg, decades) and perhaps less common than previously thought., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00344903., (© 2017 American Heart Association, Inc.)

Background: It is well known that the maternal cardiovascular system undergoes profound alterations throughout pregnancy. Interest in understanding these changes has led investigators to use evolving and increasingly sophisticated techniques to study these changes, most recently with 2-dimensional echocardiography. Despite its clinical utility, echocardiography has limitations, and cardiac magnetic resonance imaging (CMRI) has become increasingly used for evaluation of cardiac structure and function., Objective: We used CMRI to evaluate cardiac remodeling according to maternal habitus throughout pregnancy and postpartum., Study Design: This was a prospective, observational study of nulliparous women aged 18-30 years, without preexisting medical conditions, conducted from October 2012 through December 2014. Women were classified according to prepregnancy body mass index (BMI) as either normal (BMI 18.5-24.9 kg/m(2)) or overweight (BMI 25-35 kg/m(2)). All women underwent CMRI during 5 epochs throughout gestation: 12-16 weeks, 26-30 weeks, 32-36 weeks, at delivery, and 3 months' postpartum. Using left ventricular mass (LVM) as a marker of cardiac remodeling, the 2 cohorts were compared., Results: There were 14 normal-weight (BMI 22.2 ± 1.3) and 9 overweight (BMI 29.1 ± 2.0) women who participated in the study. Beginning at 26-30 weeks and continuing to delivery, LVM of both normal-weight and overweight women was significantly increased compared with the respective first-trimester studies for each cohort (P < .001). LVM of both cohorts returned to their index values by 3 months' postpartum. The geometric ratio of LVM to left ventricular end-diastolic volume was calculated, and both normal-weight and overweight women demonstrated concentric remodeling throughout gestation, however this resolved by 12 weeks' postpartum., Conclusion: There is substantial cardiac remodeling during pregnancy with significant increases in LVM that are proportional to maternal size. Left ventricular geometric remodeling was concentric in both normal-weight and overweight women. All changes in cardiac remodeling resolved by 3 months' postpartum., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objectives: The goal of this study was to determine if biomarkers of subclinical myocardial injury and hemodynamic stress identify asymptomatic individuals with left ventricular hypertrophy (LVH) at higher risk for heart failure (HF) and death., Background: The interaction between LVH, low but detectable cardiac troponin T (cTnT), and elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) on cardiovascular (CV) outcomes in the general population is unknown., Methods: Participants in the Dallas Heart Study without clinical HF, LV dysfunction, or chronic kidney disease underwent measurement of LV mass by magnetic resonance imaging (MRI), cTnT by highly sensitive assay, and NT-proBNP analysis (n = 2,413). Subjects were stratified according to LVH and by detectable cTnT (≥3 pg/ml) and increased NT-proBNP (>75th age- and sex-specific percentile) levels. For each analysis, participants were categorized into groups based on the presence (+) or absence (-) of LVH and biomarker levels above (+) or below (-) the predefined threshold., Results: Nine percent of participants were LVH+, 25% cTnT+, and 24% NT-proBNP+. Those LVH+ and cTnT+ and/or NT-proBNP+ (n = 144) were older and more likely to be male, with a greater risk factor burden and more severe LVH compared with those who were LVH+ biomarker- (p < 0.01 for each). The cumulative incidence of HF or CV death over 8 years among LVH+ cTnT+ was 21% versus 1% (LVH- cTnT-), 4% (LVH- cTnT+), and 6% (LVH+ cTnT-) (p < 0.0001). The interactions between LVH and cTnT (p(interaction) = 0.0005) and LVH and NT-proBNP (p(interaction) = 0.014) were highly significant. Individuals who were LVH+ and either cTnT+ or NT-proBNP+ remained at >4-fold higher risk for HF or CV death after multivariable adjustment for CV risk factors, renal function, and LV mass compared with those who were LVH- biomarker-., Conclusions: Minimal elevations in biomarkers of subclinical cardiac injury and hemodynamic stress modify the association of LVH with adverse outcomes, identifying a malignant subphenotype of LVH with high risk for progression to HF and CV death., (Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Whether concentric left ventricular (LV) hypertrophy (LVH) is a common precursor to depressed LV ejection fraction (EF) in humans is uncertain. From 1992 through 1994, 555 patients at our institution underwent echocardiography and had LVH (posterior or septal wall thickness ≥1.3 cm or concentric LVH noted) and normal LVEF. Of these, 220 (40%) had a follow-up assessment of LVEF by December 2008. The duration of follow-up was classified as short (≤7.5 years) or long (>7.5 years) term. The primary outcome was the development of a qualitatively depressed LVEF (mildly, moderately, or severely depressed). After a median follow-up of 7.5 years, 20% of the patients with concentric LVH developed a low LVEF. A low LVEF developed in 13% of subjects without interval myocardial infarction (MI) and 50% of subjects with interval MI during short-term follow-up (p <0.005). A low LVEF developed in 20% of subjects without interval MI and 44% of subjects with interval MI during long-term follow-up (p = 0.01). Of the subjects who developed a reduced LVEF, the relative wall thickness (median 0.5, 25th to 75th percentile 0.4 to 0.6) at follow-up was consistent with a concentric, rather than eccentric, phenotype. In conclusion, in patients with concentric LVH, the transition from a normal LVEF to a low LVEF was relatively infrequent (20%) after long-term follow-up in the absence of interval MI and usually did not result in a change in the LV geometry from a concentric to an eccentric phenotype., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Concentric left ventricular (LV) hypertrophy develops in response to a chronically increased LV afterload and is associated with increased cardiovascular events. Although the progression to systolic and diastolic heart failure is a known consequence of LV hypertrophy, few data are available on the frequency of deterioration to systolic dysfunction in patients with LV hypertrophy who originally had a normal LV ejection fraction. We evaluated the baseline and follow-up characteristics in 1,024 patients with concentric LV hypertrophy and a normal ejection fraction who had paired echocardiograms that were separated by ≥1 year. Systolic dysfunction occurred in 134 patients (13%) after a mean follow-up of 33 ± 24 months. The most common associated variable was interval myocardial infarction, which occurred in 43% of patients. Other risk factors for developing LV systolic dysfunction included QRS prolongation (>120 ms) and elevated follow-up arterial impedance defined as a value >4.0 mm Hg/ml/m(2). Patients with either a prolonged QRS interval or an elevated follow-up arterial impedance had twice the likelihood of developing LV systolic dysfunction, and, if both factors were present, there was a greater than fourfold increased risk of developing systolic dysfunction. Blood pressure measurements alone did not adequately reflect an elevated arterial impedance. In conclusion, 13% of patients with a normal ejection fraction and concentric LV hypertrophy progress to systolic dysfunction during approximately 3 years of follow-up. The risk factors for loss of function were interval myocardial infarction, prolonged QRS, and chronically elevated arterial impedance., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Osteoprotegerin, a member of the tumor necrosis factor receptor superfamily, has pleiotropic effects on bone metabolism, endocrine function, and the immune system. Myocardial expression and circulating levels of osteoprotegerin are increased in heart failure. The relationship between osteoprotegerin levels in the general population and indices of left ventricular structure and function is unknown. Plasma osteoprotegerin levels and cardiac MRI indices of left ventricular structure and function were available in 2715 subjects (median age: 44 years; 45% male) enrolled in the Dallas Heart Study. The associations between osteoprotegerin concentration and indices of left ventricular structure and function were assessed by linear regression analysis, adjusting for possible confounders. By gender-specific linear regression analysis, higher osteoprotegerin levels were significantly associated with higher left ventricular mass, left ventricular wall thickness, left ventricular concentricity index, and lower left ventricular ejection fraction (P<0.001 for all). After adjustment for age, race, fat-free mass, fat mass, hypertension, diabetes, coronary artery disease, estimated glomerular filtration rate, hypercholesterolemia, smoking status, hormone replacement therapy, coronary artery calcium score >10, and presence of aortic plaque, osteoprotegerin remained significantly associated with each of these left ventricular indices among male subjects (P<0.05 for each). Among female subjects, higher osteoprotegerin was independently associated with higher left ventricular end-systolic volume and lower ejection fraction (P<0.0001 for each) but not with indices of left ventricular hypertrophy. These findings are compatible with the theory that osteoprotegerin may play a pathophysiological role in the development of left ventricular hypertrophy and systolic dysfunction.

Our laboratory has been testing the hypothesis that genetic modulation of the beta-adrenergic signaling cascade can enhance cardiac function. We have previously shown that transgenic mice with cardiac overexpression of either the human beta2-adrenergic receptor (beta2AR) or an inhibitor of the beta-adrenergic receptor kinase (betaARK), an enzyme that phosphorylates and uncouples agonist-bound receptors, have increased myocardial inotropy. We now have created recombinant adenoviruses encoding either the beta2AR (Adeno-beta2AR) or a peptide betaARK inhibitor (consisting of the carboxyl terminus of betaARK1, Adeno-betaARKct) and tested their ability to potentiate beta-adrenergic signaling in cultured adult rabbit ventricular myocytes. As assessed by radioligand binding, Adeno-beta2AR infection led to approximately 20-fold overexpression of beta-adrenergic receptors. Protein immunoblots demonstrated the presence of the Adeno-betaARKct transgene. Both transgenes significantly increased isoproterenol-stimulated cAMP as compared to myocytes infected with an adenovirus encoding beta-galactosidase (Adeno-betaGal) but did not affect the sarcolemmal adenylyl cyclase response to Forskolin or NaF. beta-Adrenergic agonist-induced desensitization was significantly inhibited in Adeno-betaARKct-infected myocytes (16+/-2%) as compared to Adeno-betaGal-infected myocytes (37+/-1%, P < 0.001). We conclude that recombinant adenoviral gene transfer of the beta2AR or an inhibitor of betaARK-mediated desensitization can potentiate beta-adrenergic signaling.