Histamine H2 Receptor Antagonists, Left Ventricular Morphology, and Heart Failure Risk: The MESA Study

BACKGROUND

Myocardial H2 receptor activation may promote cardiac fibrosis and apoptosis in pre-clinical models and histamine H2 receptor antagonist (H2RA) use may improve symptoms in participants with heart failure (HF); however, relationships between H2RA use, incident HF, and longitudinal change in left ventricular (LV) morphology are not known.

OBJECTIVES

This study sought to determine whether H2RA use is associated with incident HF and change in LV morphology over time.

METHODS

We included 6,378 men and women from MESA (Multi-Ethnic Study of Atherosclerosis), a multicenter prospective observational cohort of participants without cardiovascular disease at baseline. Cox proportional hazards were used to estimate the association between H2RA use and incident HF in adjusted models. In participants with cardiac magnetic resonance imaging, associations between H2RA use, baseline LV morphology (n = 4,691), and longitudinal change in the LV (n = 2,806) were estimated using linear regression.

RESULTS

H2RAs were used by 313 participants but not by the other 6,065 individuals. During a median follow-up of 11.2 years, 236 participants developed HF. In adjusted models, baseline H2RA use relative to nonuse was associated with 62% lower risk for incident HF (p = 0.02). H2RA use was associated with preserved stroke volume, LV end-diastolic volume, and mass/volume ratio as measured by cardiac magnetic resonance imaging over approximately 10 years (all p < 0.05). There were no associations between H2RA use and LV mass or ejection fraction.

CONCLUSIONS

H2RA use was associated with reduced risk for incident HF. Left heart morphology over time suggests less age-related change in H2RA users. These associations suggest histamine signaling may be important in the pathogenesis of HF. (Multi-Ethnic Study of Atherosclerosis [MESA]; NCT00005487).

Myocardial microRNAs associated with reverse remodeling in human heart failure

BACKGROUND

In dilated cardiomyopathies (DCMs) changes in expression of protein-coding genes are associated with reverse remodeling, and these changes can be regulated by microRNAs (miRs). We tested the general hypothesis that dynamic changes in myocardial miR expression are predictive of β-blocker-associated reverse remodeling.

METHODS

Forty-three idiopathic DCM patients (mean left ventricular ejection fraction 0.24 ± 0.09) were treated with β-blockers. Serial ventriculography and endomyocardial biopsies were performed at baseline, and after 3 and 12 months of treatment. Changes in RT-PCR (candidate miRs) or array-measured miRs were compared based on the presence (R) or absence (NR) of a reverse-remodeling response, and a miR-mRNA-function pathway analysis (PA) was performed.

RESULTS

At 3 months, 2 candidate miRs were selectively changed in Rs, decreases in miR-208a-3p and miR-591. PA revealed changes in miR-mRNA interactions predictive of decreased apoptosis and myocardial cell death. At 12 months, 5 miRs exhibited selective changes in Rs (decreases in miR-208a-3p, -208b-3p, 21-5p, and 199a-5p; increase in miR-1-3p). PA predicted decreases in apoptosis, cardiac myocyte cell death, hypertrophy, and heart failure, with increases in contractile and overall cardiac functions.

CONCLUSIONS

In DCMs, myocardial miRs predict the time-dependent reverse-remodeling response to β-blocker treatment, and likely regulate the expression of remodeling-associated miRs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01798992.

FUNDING

NIH 2R01 HL48013, 1R01 HL71118 (Bristow, PI); sponsored research agreements from Glaxo-SmithKline and AstraZeneca (Bristow, PI); NIH P20 HL101435 (Lowes, Port multi-PD/PI); sponsored research agreement from Miragen Therapeutics (Port, PI).

Lessons Learned and Insights Gained in the Design, Analysis, and Outcomes of the COMPANION Trial

COMPANION (Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure), the first cardiac resynchronization therapy (CRT)-heart failure mortality and morbidity controlled clinical trial planned, conducted, and reported, was a randomized, 3-arm study that compared CRT delivered by a biventricular pacemaker (CRT-P) or a CRT defibrillator device (CRT-D) with optimal pharmacological therapy alone. The patient population had advanced chronic heart failure with QRS interval prolongation ≥120 ms and reduced left ventricular ejection fraction (heart failure with reduced ejection fraction). COMPANION had a composite hospitalization and mortality endpoint as the primary outcome measure but was also powered for mortality as the first secondary endpoint. The conduct of COMPANION was challenged by important issues that arose during the trial, the most important of which was U.S. Food and Drug Administration approval of CRT devices. Along with other challenges, this issue was appropriately dealt with by the Steering Committee and the Data and Safety Monitoring Committee and did not negatively affect trial results or conclusions. The authors report here updated analyses from the study, which are consistent with previously published results indicating that CRT-P or CRT-D has favorable effects on heart failure morbidity and mortality in a patient population "precision" selected by the surrogate marker of increased QRS interval duration. New analyses indicate that increasing the number of classes of neurohormonal inhibitor concurrent therapy has a positive effect on CRT mortality reduction. Hypothesis-generating new findings are that in patients receiving beta-blocker therapy, the mortality reduction advantage of CRT-D versus CRT-P may be minimized or eliminated and that there may be adverse effects of CRT-D defibrillator shocks on pump failure-related outcomes.

Detection and Management of Geographic Disparities in the TOPCAT Trial: Lessons Learned and Derivative Recommendations

TOPCAT (Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist Trial) was a multinational clinical trial of 3,445 heart failure with preserved ejection fraction patients that enrolled in 233 sites in 6 countries in North America, Eastern Europe, and South America. Patients with a heart failure hospitalization in the last 12 months or an elevated B-type natriuretic peptide were randomized to the mineralocorticoid receptor antagonist spironolactone versus placebo. Sites in Russia and the Republic of Georgia provided the majority of early enrollment, primarily based on the hospitalization criterion because B-type natriuretic peptide levels were initially unavailable there. With the emergence of country-specific aggregate event rate data indicating lower rates in Eastern Europe and differences in patient characteristics there, the Data Safety and Monitoring Board recommended relatively increasing enrollment in North America plus other corrective measures. Although final enrollment reflected the increased contribution from North America, a plurality of the final cohort came from Russia and Georgia (49% vs. 43% in North America). B-type natriuretic peptide measurements from Russia and Georgia, available later in the trial, suggested no or a mild level of heart failure consistent with low event rates. The primary results showed no significant spironolactone treatment effect overall (primary endpoint hazard ratio [HR]: 0.89; 95% confidence interval [CI]: 0.77 to 1.04), with a significant hazard ratio in North and South America (HR: 0.82; 95% CI: 0.69 to 0.98; p = 0.026) but not in Russia and Georgia (HR: 1.10; 95% CI: 0.79 to 1.51; interaction p = 0.12). This report describes the Data Safety and Monitoring Board’s detection and management recommendations for regional differences in patient characteristics in TOPCAT and suggests methods of surveillance and corrective actions that may be useful for future trials. (Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist Trial [TOPCAT]; NCT00094302)

Sex-related differences in age-associated downregulation of human ventricular myocardial β1-adrenergic receptors

BACKGROUND

With increasing age, human ventricular myocardium exhibits selective downregulation of β1-adrenergic receptors (β1-ARs). We tested the hypothesis that sex differences exist in age-related changes in β1-ARs.

METHODS

Left (LV) and right (RV) ventricular tissue was obtained from 61 unplaceable potential organ donor hearts ages 1 to 71 years with no known cardiac history and from LVs removed from 56 transplant recipients with idiopathic dilated cardiomyopathy. β1-AR and β2-AR densities, the frequency of β1-AR389 gene variants, and β-AR function were determined.

RESULTS

Sex had a marked effect on the age-related decrease in β1-ARs. Female LVs had more pronounced downregulation (by 42% [p < 0.001] vs 22% [p = 0.21] in 31 male LVs) comparing the youngest (average age, 15.3 ± 5.5 years) to the oldest (average age, 50.8 ± 9.1 years) sub-groups. On regression analyses, female LVs exhibited a closer relationship between β1-AR density and age (r = -0.78, p <0.001 vs r = -0.46, p = 0.009 in males), with a second-degree polynomial yielding the best fit. There was no statistically significant relationship of β1-ARs to age in female or male idiopathic dilated cardiomyopathy LVs.

CONCLUSIONS

Sex affects age-related β-AR downregulation in normal human ventricles, with females exhibiting more profound decreases with increasing age. The curvilinear relationship between age and receptor density that plateaus around age 40 in women suggests an effect of sex hormones on β1-AR expression in the human heart.

The adrenergic system in pulmonary arterial hypertension: bench to bedside (2013 Grover Conference series)

In heart failure with reduced left ventricular ejection fraction (HFrEF), adrenergic activation is a key compensatory mechanism that is a major contributor to progressive ventricular remodeling and worsening of heart failure. Targeting the increased adrenergic activation with β-adrenergic receptor blocking agents has led to the development of arguably the single most effective drug therapy for HFrEF. The pressure-overloaded and ultimately remodeled/failing right ventricle (RV) in pulmonary arterial hypertension (PAH) is also adrenergically activated, which raises the issue of whether an antiadrenergic strategy could be effectively employed in this setting. Anecdotal experience suggests that it will be challenging to administer an antiadrenergic treatment such as a β-blocking agent to patients with established moderate-severe PAH. However, the same types of data and commentary were prevalent early in the development of β-blockade for HFrEF treatment. In addition, in HFrEF approaches have been developed for delivering β-blocker therapy to patients who have extremely advanced heart failure, and these general principles could be applied to RV failure in PAH. This review examines the role played by adrenergic activation in the RV faced with PAH, contrasts PAH-RV remodeling with left ventricle remodeling in settings of sustained increases in afterload, and suggests a possible approach for safely delivering an antiadrenergic treatment to patients with RV dysfunction due to moderate-severe PAH.

Cardiovascular drug development: is it dead or just hibernating?

Despite the global burden of cardiovascular disease, investment in cardiovascular drug development has stagnated over the past 2 decades, with relative underinvestment compared with other therapeutic areas. The reasons for this trend are multifactorial, but of primary concern is the high cost of conducting cardiovascular outcome trials in the current regulatory environment that demands a direct assessment of risks and benefits, using clinically-evident cardiovascular endpoints. To work toward consensus on improving the environment for cardiovascular drug development, stakeholders from academia, industry, regulatory bodies, and government agencies convened for a think tank meeting in July 2014 in Washington, DC. This paper summarizes the proceedings of the meeting and aims to delineate the current adverse trends in cardiovascular drug development, understand the key issues that underlie these trends within the context of a recognized need for a rigorous regulatory review process, and provide potential solutions to the problems identified.

Visual analysis of biological data-knowledge networks

BACKGROUND

The interpretation of the results from genome-scale experiments is a challenging and important problem in contemporary biomedical research. Biological networks that integrate experimental results with existing knowledge from biomedical databases and published literature can provide a rich resource and powerful basis for hypothesizing about mechanistic explanations for observed gene-phenotype relationships. However, the size and density of such networks often impede their efficient exploration and understanding.

RESULTS

We introduce a visual analytics approach that integrates interactive filtering of dense networks based on degree-of-interest functions with attribute-based layouts of the resulting subnetworks. The comparison of multiple subnetworks representing different analysis facets is facilitated through an interactive super-network that integrates brushing-and-linking techniques for highlighting components across networks. An implementation is freely available as a Cytoscape app.

CONCLUSIONS

We demonstrate the utility of our approach through two case studies using a dataset that combines clinical data with high-throughput data for studying the effect of β-blocker treatment on heart failure patients. Furthermore, we discuss our team-based iterative design and development process as well as the limitations and generalizability of our approach.

Therapeutic Molecular Phenotype of β-Blocker-Associated Reverse-Remodeling in Nonischemic Dilated Cardiomyopathy

BACKGROUND

When β-blockers produce reverse-remodeling in idiopathic dilated cardiomyopathy, they partially reverse changes in fetal-adult/contractile protein, natriuretic peptide, SR-Ca(2+)-ATPase gene program constituents. The objective of the current study was to further test the hypothesis that reverse-remodeling is associated with favorable changes in myocardial gene expression by measuring additional contractile, signaling, and metabolic genes that exhibit a fetal/adult expression predominance, are thyroid hormone-responsive, and are regulated by β1-adrenergic receptor signaling. A secondary objective was to identify which of these putative regulatory networks is most closely associated with observed changes.

METHODS AND RESULTS

Forty-seven patients with idiopathic dilated cardiomyopathy (left ventricular ejection fraction, 0.24±0.09) were randomized to the adrenergic-receptor blockers metoprolol (β1-selective), metoprolol+doxazosin (β1/α1), or carvedilol (β1/β2/α1). Serial radionuclide ventriculography and endomyocardial biopsies were performed at baseline, 3, and 12 months. Expression of 50 mRNA gene products was measured by quantitative polymerase chain reaction. Thirty-one patients achieved left ventricular ejection fraction reverse-remodeling response defined as improvement by ≥0.08 at 12 months or by ≥0.05 at 3 months (Δ left ventricular ejection fraction, 0.21±0.10). Changes in gene expression in responders versus nonresponders were decreases in NPPA and NPPB and increases in MYH6, ATP2A2, PLN, RYR2, ADRA1A, ADRB1, MYL3, PDFKM, PDHX, and CPT1B. All except PDHX involved increase in adult or decrease in fetal cardiac genes, but 100% were concordant with changes predicted by inhibition of β1-adrenergic signaling.

CONCLUSIONS

In addition to known gene expression changes, additional calcium-handling, sarcomeric, adrenergic signaling, and metabolic genes were associated with reverse-remodeling. The pattern suggests a fetal-adult paradigm but may be because of reversal of gene expression controlled by a β1-adrenergic receptor gene network.

CLINICAL TRIAL REGISTRATION

URL: www.clinicaltrials.gov. Unique Identifier: NCT01798992.

Genetic variants are not associated with outcome in patients with coronary artery disease and left ventricular dysfunction: results of the Genetic Substudy of the Surgical Treatment for Ischemic Heart Failure (STICH) trials

OBJECTIVES AND BACKGROUND

We evaluated the ability of 23 genetic variants to provide prognostic information in patients enrolled in the Genetic Substudy of the Surgical Treatment for Ischemic Heart Failure (STICH) trials.

METHODS

Patients assigned to STICH Hypothesis 1 were randomized to medical therapy with or without coronary artery bypass grafting (CABG). Those assigned to STICH Hypothesis 2 were randomized to CABG or CABG with left ventricular reconstruction.

RESULTS

In patients assigned to STICH Hypothesis 2 (n = 714), no genetic variant met the prespecified Bonferroni-adjusted threshold for statistical significance (p < 0.002); however, several variants met nominal prognostic significance: variants in the β2-adrenergic receptor gene (β2-AR Gln27Glu) and in the A1-adenosine receptor gene (A1-717 T/G) were associated with an increased risk of a subject dying or being hospitalized for a cardiac problem (p = 0.027 and 0.031, respectively). These relationships remained nominally significant even after multivariable adjustment for prognostic clinical variables. However, none of the 23 genetic variants influenced all-cause mortality or the combination of death or cardiovascular hospitalization in the STICH Hypothesis 1 population (n = 532) by either univariate or multivariable analysis.

CONCLUSION

We were unable to identify the predictive genotypes in optimally treated patients in these two ischemic heart failure populations.

Peax: interactive visual analysis and exploration of complex clinical phenotype and gene expression association

Increasing availability of high-dimensional clinical data, which improves the ability to define more specific phenotypes, as well as molecular data, which can elucidate disease mechanisms, is a driving force and at the same time a major challenge for translational and personalized medicine. Successful research in this field requires an approach that ties together specific disease and health expertise with understanding of molecular data through statistical methods. We present PEAX (Phenotype-Expression Association eXplorer), built upon open-source software, which integrates visual phenotype model definition with statistical testing of expression data presented concurrently in a web-browser. The integration of data and analysis tasks in a single tool allows clinical domain experts to obtain new insights directly through exploration of relationships between multivariate phenotype models and gene expression data, showing the effects of model definition and modification while also exploiting potential meaningful associations between phenotype and miRNA-mRNA regulatory relationships. We combine the web visualization capabilities of Shiny and D3 with the power and speed of R for backend statistical analysis, in order to abstract the scripting required for repetitive analysis of sub-phenotype association. We describe the motivation for PEAX, demonstrate its utility through a use case involving heart failure research, and discuss computational challenges and observations. We show that our visual web-based representations are well-suited for rapid exploration of phenotype and gene expression association, facilitating insight and discovery by domain experts.

Prevention of atrial fibrillation by bucindolol is dependent on the beta₁389 Arg/Gly adrenergic receptor polymorphism

OBJECTIVES

This study assessed the impact of bucindolol, a beta-blocker/sympatholytic agent, on the development of atrial fibrillation (AF) in advanced chronic heart failure with reduced left ventricular ejection fraction (HFREF) patients enrolled in the BEST (Beta-Blocker Evaluation of Survival Trial).

BACKGROUND

β-blockers have modest efficacy for AF prevention in HFREF patients. Bucindolol's effects on HF and ventricular arrhythmic endpoints are genetically modulated by β₁- and α(2c)-adrenergic receptor (AR) polymorphisms that can be used to subdivide HFREF populations into those with bucindolol effectiveness levels that are enhanced, unchanged, or lost.

METHODS

BEST enrolled 2,708 New York Heart Association (NYHA) class III to IV HFREF patients. A substudy in which 1,040 patients' DNA was genotyped for the β₁-AR position 389 Arg/Gly and the α(2c)322-325 wild type (Wt)/deletion (Del) polymorphisms, and new-onset AF was assessed from adverse event case report forms or electrocardiograms at baseline and at 3 and 12 months.

RESULTS

In the entire cohort, bucindolol reduced the rate of new-onset AF compared to placebo by 41% (hazard ratio [HR]: 0.59 [95% confidence interval (CI): 0.44 to 0.79], p = 0.0004). In the 493 β₁389 arginine homozygotes (Arg/Arg) in the DNA substudy, bucindolol reduced new-onset AF by 74% (HR: 0.26 [95% CI: 0.12 to 0.57]), with no effect in β₁389 Gly carriers (HR: 1.01 [95% CI: 0.56 to 1.84], interaction test = 0.008). When β₁389 Gly carriers were subdivided by α(2c) Wt homozygotes (n = 413, HR: 0.94 [95% CI: 0.48 to 1.82], p = 0.84) or Del variant carriers (n = 134, HR: 1.33 [95% CI: 0.32 to 5.64], p = 0.70), there was a positive interaction test (p = 0.016) when analyzed with β₁389 Arg homozygotes.

CONCLUSIONS

Bucindolol prevented new-onset AF; β₁ and α(2c) polymorphisms predicted therapeutic response; and the 47% of patients who were β₁389 Arg homozygotes had an enhanced effect size of 74%. (Beta-Blocker Evaluation in Survival Trial [BEST]; NCT00000560)

Race, common genetic variation, and therapeutic response disparities in heart failure

Because of its comparatively recent evolution, Homo sapiens exhibit relatively little within-species genomic diversity. However, because of genome size, a proportionately small amount of variation creates ample opportunities for both rare mutations that may cause disease as well as more common genetic variations that may be important in disease modification or pharmacogenetics. Primarily because of the East African origin of modern humans, individuals of African ancestry (AA) exhibit greater degrees of genetic diversity than more recently established populations, such as those of European ancestry (EA) or Asian ancestry. Those population effects extend to differences in frequency of common gene variants that may be important in heart failure natural history or therapy. For cell-signaling mechanisms important in heart failure, we review and present new data for genetic variation between AA and EA populations. Data indicate that: 1) neurohormonal signaling mechanisms frequently (16 of the 19 investigated polymorphisms) exhibit racial differences in the allele frequencies of variants comprising key constituents; 2) some of these differences in allele frequency may differentially affect the natural history of heart failure in AA compared with EA individuals; and 3) in many cases, these differences likely play a role in observed racial differences in drug or device response.

New-onset atrial fibrillation predicts heart failure progression

BACKGROUND

Atrial fibrillation and heart failure with reduced left ventricular ejection fraction have interrelated pathophysiologies. New-onset atrial fibrillation in heart failure patients has been associated with increased mortality, but has not been definitively related to clinical heart failure progression.

METHODS

To test the hypothesis that new-onset atrial fibrillation is related to clinical heart failure progression, in 2392 patients without atrial fibrillation at randomization in the Beta-blocker Evaluation of Survival Trial we measured clinical endpoints in patients who did (Group 1, n = 190) or did not (Group 2, n = 2202) develop new-onset atrial fibrillation. Results were also compared with the 303 patients who entered the trial in atrial fibrillation (Baseline/chronic group), and in Group 1/2 patients we conducted a multivariate analysis of covariates potentially related to time to first heart failure hospitalization.

RESULTS

Compared with Group 2, Group 1 patients post atrial fibrillation onset had a ∼2-fold increase in mortality (P < .0001) and a ∼4.5-fold increase in all-cause or heart failure hospitalization days/patient (hospitalization burden, both P < .0001). In Group 1, both types of hospitalization burden were 2.9-fold greater than in the Baseline/chronic group (P < .001), and hospitalization burden increased ∼6-fold (P < .0001) compared with the pre-event period. On multivariate analysis, new-onset atrial fibrillation was a highly significant (P < .00001) predictor of heart failure hospitalization.

CONCLUSIONS

In addition to being a discrete electrophysiologic event, in heart failure patients, new-onset atrial fibrillation is a predictor of and trigger for clinical heart failure progression.

Prognostic significance of biomarkers in predicting outcome in patients with coronary artery disease and left ventricular dysfunction: results of the biomarker substudy of the Surgical Treatment for Ischemic Heart Failure trials

BACKGROUND

Patients with heart failure and coronary artery disease often undergo coronary artery bypass grafting, but assessment of the risk of an adverse outcome in these patients is difficult. To evaluate the ability of biomarkers to contribute independent prognostic information in these patients, we measured levels in patients enrolled in the biomarker substudies of the Surgical Treatment for Ischemic Heart Failure (STICH) trials. Patients in STICH Hypothesis 1 were randomized to medical therapy or coronary artery bypass grafting, whereas those in STICH Hypothesis 2 were randomized to coronary artery bypass grafting or coronary artery bypass grafting with left ventricular reconstruction.

METHODS AND RESULTS

In substudy patients assigned to STICH Hypothesis 1 (n=606), plasma levels of soluble tumor necrosis factor-α receptor-1 (sTNFR-1) and brain natriuretic peptide (BNP) were highly predictive of the primary outcome variable of mortality by univariate analysis (BNP: χ(2)=40.6; P<0.0001 and sTNFR-1: χ(2)=38.9; P<0.0001). When considered in the context of multivariable analysis, both BNP and sTNFR-1 contributed independent prognostic information beyond the information provided by a large array of clinical factors independent of treatment assignment. Consistent results were seen when assessing the predictive value of BNP and sTNFR-1 in patients assigned to STICH Hypothesis 2 (n=626). Both plasma levels of BNP (χ(2)=30.3) and sTNFR-1 (χ(2)=45.5) were highly predictive in univariate analysis (P<0.0001) and in multivariable analysis for the primary end point of death or cardiac hospitalization. In multivariable analysis, the prognostic information contributed by BNP (χ(2)=6.0; P=0.049) and sTNFR-1 (χ(2)=8.8; P=0.003) remained statistically significant even after accounting for other clinical information. Although the biomarkers added little discriminatory improvement to the clinical factors (increase in c-index ≤0.1), net reclassification improvement for the primary end points was 0.29 for BNP and 0.21 for sTNFR-1 in the Hypothesis 1 cohort, and 0.15 for BNP and 0.30 for sTNFR-1 in the Hypothesis 2 cohort, reflecting important predictive improvement.

CONCLUSIONS

Elevated levels of sTNFR-1 and BNP are strongly associated with outcomes, independent of therapy, in 2 large and independent studies, thus providing important cross-validation for the prognostic importance of these 2 biomarkers.

Adrenergic receptor polymorphisms and prevention of ventricular arrhythmias with bucindolol in patients with chronic heart failure

BACKGROUND

β-blockers prevent cardiac arrhythmias in patients with chronic heart failure and reduced left ventricular ejection fraction, including ventricular tachycardia/ventricular fibrillation (VT/VF). We hypothesized that prevention of ventricular arrhythmias by the β-blocker/sympatholytic agent bucindolol is influenced by genetic variation in adrenergic receptors.

METHODS AND RESULTS

From a substudy of the β-Blocker Evaluation of Survival Trial (n=1040), we identified those with the high functioning 389Arg versus the lower function 389Gly β(1) adrenergic receptor variant, and the loss of function α(2c)322-325 adrenergic receptor deletion versus the 322 to 325 wild-type (Wt)/deletion variant. VT/VF was recorded on case report forms as an adverse event. There were 493 Arg 389 β(1) receptor homozygotes (β(1)389 Arg/Arg) versus 547 Gly389 carriers and 207 α(2c)322-325 deletion carriers versus 833 homozygous Wts (α(2c)322-325 Wt/Wt). In all genotypes bucindolol was associated with a lower incidence of VT/VF (subhazard ratio, 0.42 [0.27-0.64]; P=0.00006). Bucindolol reduced VT/VF in β(1)389 Arg homozygotes (subhazard ratio, 0.26 [0.14-0.50]; P=0.00005) but not in β(1)389 Gly carriers (subhazard ratio, 0.60 [0.34-1.07]; P=0.09). For genotype combinations, the α(2c)322-325 polymorphism altered the VT/VF bucindolol response in β1389 Gly carriers, with α(2c) deletion genotypes associated with complete efficacy loss. A test of interaction was statistically significant (P=0.028) for the treatment group and a β(1)389/α(2c)322-325 three genotype construct, effectively identifying patients who exhibited enhanced response, no substantial response modification and loss of response.

CONCLUSIONS

Bucindolol prevents VT/VF in subjects with heart failure and reduced left ventricular ejection fractions, and this effect is modulated by β(1)389 Arg/Gly and α(2c)322-325 Wt/deletion adrenergic receptor polymorphisms.

Von Willebrand factor and the right ventricle (the MESA-Right Ventricle Study)

Elevation in plasma activity of von Willebrand factor (vWF) reflects endothelial dysfunction and predicts death in pulmonary arterial hypertension. Higher vWF activity is also associated with a lower right ventricular (RV) ejection fraction in pulmonary arterial hypertension. Little is known about the relation between vWF and RV structure and function in adults without cardiovascular disease. The present investigation included 1,976 participants with magnetic resonance imaging assessment of RV structure and function and measurement of vWF activity from the Multi-Ethnic Study of Atherosclerosis. Multivariable linear regression was used to estimate the associations between vWF activity and measures of RV structure and function after adjusting for demographics, anthropometrics, smoking, diabetes mellitus, hypertension, and the corresponding left ventricular parameter. The average vWF activity was 140.7 ± 57.2%. Elevated vWF activity was independently associated with lower RV mass, RV end-diastolic volume, and RV stroke volume in models with and without adjustment for the corresponding left ventricular parameter (all p values <0.05). There was no association observed between vWF activity and the RV ejection fraction. In conclusion, higher vWF activity is associated with lower RV mass, RV end-diastolic volume, and RV stroke volume. These associations are independent of common cardiovascular risk factors and left ventricular morphologic changes.

The renin-angiotensin system and right ventricular structure and function: The MESA-Right Ventricle Study

The pulmonary vasculature is an important site of renin-angiotensin metabolism. While angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (collectively AIABs) have a role in left ventricular (LV) disease, the impact of AIABs on right ventricular (RV) function is unknown. AIAB use was determined by medication inventory during the Multi-Ethnic Study of Atherosclerosis baseline examination. RV measures were obtained via cardiac magnetic resonance imaging. The relationship between AIAB use and RV measures was assessed using multivariable linear regression, stratified by race/ethnicity, and adjusted for multiple covariates. AIAB use was associated with lower RV mass (-0.7 g, 95% confidence interval [CI] -1.3 to -0.1, P=0.03) in African Americans (N=1012) after adjustment for multiple covariates including LV mass. Among Caucasians (N=1591), AIAB use was associated with larger RV end-diastolic volume (3.7 mL, 95% CI 0.7-6.8, P=0.02) after adjustment for LV volume. No significant associations were seen between AIAB use and other RV measures or in Hispanic or Chinese American participants. AIAB use was associated with RV morphology in a race-specific and LV-independent manner, suggesting the renin-angiotensin system may play a unique role in RV structure and function. The use of AIABs in those with RV dysfunction warrants further study.

Effect of bucindolol on heart failure outcomes and heart rate response in patients with reduced ejection fraction heart failure and atrial fibrillation

AIMS

There is little evidence of beta-blocker treatment benefit in patients with heart failure and reduced left ventricular ejection fraction (HFREF) and atrial fibrillation (AF). We investigated the effects of bucindolol in HFREF patients with AF enrolled in the Beta-blocker Evaluation of Survival Trial (BEST).

METHODS AND RESULTS

A post-hoc analysis of patients in BEST with and without AF was performed to estimate the effect of bucindolol on mortality and hospitalization. Patients were also evaluated for treatment effects on heart rate and the influence of beta1-adrenergic receptor position 389 (β(1)389) arginine (Arg) vs. glycine (Gly) genotypes. In the 303/2708 patients in AF, patients receiving bucindolol were more likely to achieve a resting heart rate ≤ 80 b.p.m. at 3 months (P < 0.005) in the absence of treatment-limiting bradycardia. In AF patients and sinus rhythm (SR) patients who achieved a resting heart rate ≤ 80 b.p.m., there were beneficial treatment effects on cardiovascular mortality/cardiovascular hospitalization [hazard ratio (HR) 0.61, P = 0.025, and 0.79, P = 0.002]. Without achieving a resting heart rate ≤ 80 b.p.m., there were no treatment effects on events in either group. β(1)389-Arg/Arg AF patients had nominally significant reductions in all-cause mortality/HF hospitalization and cardiovascular mortality/hospitalization with bucindolol (HR 0.23, P = 0.037 and 0.28, P = 0.039), whereas Gly carriers did not. There was no evidence of diminished heart rate response in β(1)389-Arg homozygotes.

CONCLUSION

In HFREF patients with AF, bucindolol was associated with reductions in composite HF endpoints in those who achieved a resting heart rate ≤ 80 b.p.m. and nominally in those with the β(1)389-Arg homozygous genotype.

A personalized BEST: characterization of latent clinical classes of nonischemic heart failure that predict outcomes and response to bucindolol

Background

Heart failure patients with reduced ejection fraction (HFREF) are heterogenous, and our ability to identify patients likely to respond to therapy is limited. We present a method of identifying disease subtypes using high-dimensional clinical phenotyping and latent class analysis that may be useful in personalizing prognosis and treatment in HFREF.

Methods

A total of 1121 patients with nonischemic HFREF from the β-blocker Evaluation of Survival Trial were categorized according to 27 clinical features. Latent class analysis was used to generate two latent class models, LCM A and B, to identify HFREF subtypes. LCM A consisted of features associated with HF pathogenesis, whereas LCM B consisted of markers of HF progression and severity. The Seattle Heart Failure Model (SHFM) Score was also calculated for all patients. Mortality, improvement in left ventricular ejection fraction (LVEF) defined as an increase in LVEF ≥5% and a final LVEF of 35% after 12 months, and effect of bucindolol on both outcomes were compared across HFREF subtypes. Performance of models that included a combination of LCM subtypes and SHFM scores towards predicting mortality and LVEF response was estimated and subsequently validated using leave-one-out cross-validation and data from the Multicenter Oral Carvedilol Heart Failure Assessment Trial.

Results

A total of 6 subtypes were identified using LCM A and 5 subtypes using LCM B. Several subtypes resembled familiar clinical phenotypes. Prognosis, improvement in LVEF, and the effect of bucindolol treatment differed significantly between subtypes. Prediction improved with addition of both latent class models to SHFM for both 1-year mortality and LVEF response outcomes.

Conclusions

The combination of high-dimensional phenotyping and latent class analysis identifies subtypes of HFREF with implications for prognosis and response to specific therapies that may provide insight into mechanisms of disease. These subtypes may facilitate development of personalized treatment plans.

Right ventricular structure is associated with the risk of heart failure and cardiovascular death: the Multi-Ethnic Study of Atherosclerosis (MESA)--right ventricle study

BACKGROUND

Changes in right ventricular (RV) morphology are associated with morbidity and mortality in heart and lung disease. We examined the association of abnormal RV structure and function with the risk of heart failure or cardiovascular death in a population-based multiethnic sample free of clinical cardiovascular disease at baseline.

METHODS AND RESULTS

The Multi-Ethnic Study of Atherosclerosis (MESA) performed cardiac magnetic resonance imaging on 5098 participants between 2000 and 2002 with follow-up for incident heart failure and cardiovascular death ("death") until January 2008. RV volumes and mass were available for 4204 participants. The study sample (n=4144) was 61.4±10.1 years old and 47.6% male. The presence of RV hypertrophy (increased RV mass) was associated with more than twice the risk of heart failure or death after adjustment for demographics, body mass index, education, C-reactive protein level, hypertension, and smoking status (hazard ratio, 2.52; 95% confidence interval, 1.55-4.10; P<0.001) and a doubling (or more) of risk with left ventricular mass at the mean value or lower (P for interaction=0.05).

CONCLUSIONS

RV hypertrophy was associated with the risk of heart failure or death in a multiethnic population free of clinical cardiovascular disease at baseline.

Pharmacogenetics in heart failure trials

There is ongoing research into potential pharmacogenetic targets in heart failure. Several challenges exist despite the potential benefits, and questions remain on the level of evidence needed to support product approval or labeling. High annual mortality, high morbidity, and heterogeneity of response to treatment underscore the need for predictability of response in this patient population. Although prime time testing and application of pharmacogenetics is not currently being used in heart failure, we believe this treatment approach is not too distant. The data are supportive, and further research is warranted to strengthen the approach.

Treatment of chronic heart failure with β-adrenergic receptor antagonists: a convergence of receptor pharmacology and clinical cardiology

Despite the absence of a systematic development plan, β-blockers have reached the top tier of medical therapies for chronic heart failure. The successful outcome was due to the many dedicated investigators who produced, over a 30-year period, increasing evidence that β-blocking agents should or actually did improve the natural history of dilated cardiomyopathies and heart failure. It took 20 years for supportive evidence to become undeniable, at which time in 1993 the formidable drug development resources of large pharmaceutical companies were deployed into Phase 3 trials. Success then came relatively quickly, and within 8 years multiple agents were on the market in the United States and Europe. Importantly, there is ample room to improve antiadrenergic therapy, through novel approaches exploiting the nuances of receptor biology and/or intracellular signaling, as well as through pharmacogenetic targeting.

Prospective-retrospective biomarker analysis for regulatory consideration: white paper from the industry pharmacogenomics working group

One approach to delivering cost-effective healthcare requires the identification of patients as individuals or subpopulations that are more likely to respond to an appropriate dose and/or schedule of a therapeutic agent, or as subpopulations that are less likely to develop an adverse event (i.e., personalized or stratified medicine). Biomarkers that identify therapeutically relevant variations in human biology are often only uncovered in the later stage of drug development. In this article, the Industry Pharmacogenomics Working Group provides, for regulatory consideration, its perspective on the rationale for the conduct of what is commonly referred to as the prospective-retrospective analysis (PRA) of biomarkers. Reflecting on published proposals and materials presented by the US FDA, a decision tree for generating robust scientific data from samples collected from an already conducted trial to allow PRA is presented. The primary utility of the PRA is to define a process that provides robust scientific evidence for decision-making in situations where it is not necessary, nor practical or ethical to conduct a new prospective clinical study.

Temporal analysis of mRNA and miRNA expression in transgenic mice overexpressing Arg- and Gly389 polymorphic variants of the β1-adrenergic receptor

Several studies in humans or transgenic animals have reported that the 389 Arg or Gly polymorphic variation of the β1-adrenergic receptor (AR) is associated with differential responses to beta-blocker therapy and/or myocardial disease progression. Analysis of changes in gene expression is an important means of defining molecular differences associated with structural or functional phenotypic variations. To determine if structural and functional myocardial phenotypic differences between β1389 Arg vs. Gly transgenic overexpressors are associated with qualitative and/or quantitative differences in gene expression, a comprehensive analysis of mRNAs and miRNAs expressed in the hearts of 3 and 6-8 mo old β1-Arg389 and β1-Gly389 overexpressor transgenic mice was performed. Changes in mRNA and miRNA expression were analyzed by arrays and partially confirmed by RT-qPCR. Bioinformatic analysis demonstrated that several genes, including those involved in PKA and CaMK signaling pathways, are regulated in a temporal- or phenotype-specific manner. Furthermore, expression signature analyses indicated that miRNAs have the potential to target expression of a number of genes involved in multiple cardiomyopathy-related pathways, and changes in miRNA expression can precede the onset of disease. Differences in gene expression between β1-Arg389 and β1-Gly389 transgenic mice are largely quantitative rather than qualitative and are associated with the development of cardiomyopathy in a time-dependent manner. Chronic β1-AR overdrive results in increased expression of components of the CaMK pathway, with correspondingly decreased levels of components of the PKA pathway. Based on the temporal and genotype-specific pattern of miRNA expression, miRNAs are likely to be important predictors of disease states, especially when miRNA expression is paired with mRNA expression, and that miRNA/mRNA expression signatures have the potential to be useful in determining the underlying risk associated with cardiac disease progression.

Sex hormones are associated with right ventricular structure and function: The MESA-right ventricle study

RATIONALE

Sex hormones have effects on the left ventricle, but hormonal influences on the right ventricle (RV) are unknown.

OBJECTIVES

We hypothesized that sex hormones would be associated with RV morphology in a large cohort free of cardiovascular disease.

METHODS

Sex hormones were measured by immunoassay and RV ejection fraction (RVEF), stroke volume (RVSV), mass, end-diastolic volume, and end-systolic volume (RVESV) were measured by cardiac magnetic resonance imaging in 1,957 men and 1,738 postmenopausal women. The relationship between each hormone and RV parameter was assessed by multivariate linear regression.

MEASUREMENTS AND MAIN RESULTS

Higher estradiol levels were associated with higher RVEF (β per 1 ln[nmol/L], 0.88; 95% confidence interval [CI], 0.32 to 1.43; P = 0.002) and lower RVESV (β per 1 ln[nmol/L], -0.87; 95% CI, -1.67 to -0.08; P = 0.03) in women using hormone therapy. In men, higher bioavailable testosterone levels were associated with higher RVSV (β per 1 ln[nmol/L], 1.97; 95% CI, 0.20 to 3.73; P = 0.03) and greater RV mass and volumes (P ≤ 0.01). Higher dehydroepiandrosterone levels were associated with higher RVSV (β per 1 ln[nmol/L], 1.37; 95% CI, 0.15 to 2.59; P = 0.03) and greater RV mass (β per 1 ln[nmol/L], 0.25; 95% CI, 0.00 to 0.49; P = 0.05) and volumes (P ≤ 0.001) in women.

CONCLUSIONS

Higher estradiol levels were associated with better RV systolic function in women using hormone therapy. Higher levels of androgens were associated with greater RV mass and volumes in both sexes.

Regional left ventricular systolic function and the right ventricle: the multi-ethnic study of atherosclerosis right ventricle study

BACKGROUND

Dysfunction of the interventricular septum has been implicated in right ventricular (RV) failure. However, little is known about the relationship between ventricular septal and RV function in patients without clinical cardiovascular disease. We hypothesized that better septal function would be associated with higher RV ejection fraction and lower RV mass and volume by cardiac MRI.

METHODS

In the Multi-Ethnic Study of Atherosclerosis (MESA), cardiac MRI was performed on community-based participants without clinical cardiovascular disease. Images were analyzed by the harmonic phase method to measure peak circumferential systolic midventricular strain for each wall (anterior, lateral, inferior, and septal). Multivariable linear regression and generalized additive models were used to assess the relationship between septal strain and RV morphology.

RESULTS

There were 917 participants (45.7% women) with a mean age of 65.7 years. Better septal function was associated with higher RV ejection fraction in a nonlinear fashion after adjustment for all covariates (P = .03). There appeared to be a threshold effect for the contribution of septal strain to RV systolic function, with an almost linear decrement in RV ejection fraction with septal strain from -18% to -10%. Septal function was not related to RV mass or volume.

CONCLUSIONS

Interventricular septal function was linked to RV systolic function independent of other left ventricular regions, even in individuals without clinical cardiovascular disease. This finding confirms animal and human research suggesting the importance of septal function to the right ventricle and implies that changes in septal function could herald RV dysfunction.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00005487; URL: www.clinicaltrials.gov.

Effects of low-dose oral enoximone administration on mortality, morbidity, and exercise capacity in patients with advanced heart failure: the randomized, double-blind, placebo-controlled, parallel group ESSENTIAL trials

Aims

Use of inotropic agents in patients with heart failure (HF) has been limited by adverse effects on outcomes. However, administration of positive inotropes at lower doses and concomitant treatment with beta-blockers might increase benefit–risk ratio. We investigated the effects of low doses of the positive inotrope enoximone on symptoms, exercise capacity, and major clinical outcomes in patients with advanced HF who were also treated with beta-blockers and other guideline-recommended background therapy.

Methods and results

The Studies of Oral Enoximone Therapy in Advanced HF (ESSENTIAL) programme consisted of two identical, randomized, double-blind, placebo-controlled trials that differed only by geographic location (North and South America: ESSENTIAL-I; Europe: ESSENTIAL-II). Patients with New York Heart Association class III–IV HF symptoms, left ventricular ejection fraction ≤30%, and one hospitalization or two ambulatory visits for worsening HF in the previous year were eligible for participation in the trials. The trials had three co-primary endpoints: (i) the composite of time to all-cause mortality or cardiovascular hospitalization, analysed in the two ESSENTIAL trials combined; (ii) the 6 month change from baseline in the 6 min walk test distance (6MWTD); and (iii) the Patient Global Assessment (PGA) at 6 months, both analysed in each trial separately. ESSENTIAL-I and -II randomized 1854 subjects at 211 sites in 16 countries. In the combined trials, all-cause mortality and the composite, first co-primary endpoint did not differ between the two treatment groups [hazard ratio (HR) 0.97; 95% confidence interval (CI) 0.80–1.17; and HR 0.98; 95% CI 0.86–1.12, respectively, for enoximone vs. placebo]. The two other co-primary endpoints were analysed separately in the two ESSENTIAL trials, as prospectively designed in the protocol. The 6MWTD increased with enoximone, compared with placebo, in ESSENTIAL-I (P = 0.025, not reaching, however, the pre-specified criterion for statistical significance of P < 0.020), but not in ESSENTIAL-II. No difference in PGA was observed in either trial.

Conclusion

Although low-dose enoximone appears to be safe in patients with advanced HF, major clinical outcomes are not improved.

Left ventricular dysfunction in murine models of heart failure and in failing human heart is associated with a selective decrease in the expression of caveolin-3

BACKGROUND

Caveolins are scaffolding proteins that are integral components of caveolae, flask-shaped invaginations in the membranes of all mammalian cells. Caveolin-1 and -2 are expressed ubiquitously, whereas caveolin-3 is found only in muscle. The role of caveolin-3 in heart muscle disease is controversial.

METHODS AND RESULTS

The present study was undertaken to assess the effects of left ventricular dysfunction on the expression of caveolin proteins using 2 well characterized models of murine heart failure and failing human heart. Transgenic mice with constitutive overexpression of A(1)-adenosine receptor (A(1)-TG) demonstrated cardiac dilatation and decreased left ventricular function at 10 weeks of age. This was accompanied by a marked decrease in caveolin-3 mRNA and protein levels compared with non-TG control mice. The change in caveolin-3 expression was selective, because levels of caveolin-1 and -2 did not change. Confocal imaging of myocytes isolated from A(1)-TG mice demonstrated a loss of the plate-like appearance of T tubules. Caveolin-3 levels were also reduced in hearts from mice overexpressing tumor necrosis factor α. There was a direct relationship between caveolin-3 expression and fractional shortening in all mice that were studied (r = 0.65; P < .001). Although we could not demonstrate a significant decrease in caveolin-3 levels in failing human heart, we did find a direct correlation (r = 0.7; P < .05) between levels of caveolin-3 protein and Ca(2+)-adenosine triphosphatase, a marker of the heart failure phenotype.

CONCLUSIONS

These results suggest a relationship between left ventricular dysfunction and caveolin-3 levels and suggest that caveolin-3 may provide a novel target for heart failure therapy.

Increased phosphorylation-dependent nuclear export of class II histone deacetylases in failing human heart

In the failing human heart (FHH) the induction of a fetal contractile protein gene program is directly and selectively associated with the dilated cardiomyopathy (DCM) phenotype and involves multiple signaling pathways. In response to cardiac stress signals, class II HDACs are subject to phosphorylation dependent nuclear export, which allows for activation of fetal cardiac genes via the transcription factor MEF2. The current study tests the hypothesis that MEF2 activation produced by class II HDAC de-repression is present in the FHH. In this study, human left ventricular tissue from nonfailing and failing adult hearts was analyzed for the presence of MEF2, HDACs 4 and 5. CaMK and HDAC kinase activities were measured in tissue homogenates. In nuclear fractions from failing ventricles, HDAC4 and HDAC5 protein was decreased versus nonfailing controls. MEF2 was not reduced in failing nuclear fractions. CaMK and HDAC kinase activities were increased in failing versus nonfailing hearts. PKCmu (PKD1) activity was increased in nuclear fractions from failing human LVs. These data provide support for decreased nuclear compartment class II HDACs in the FHH, associated with increased activities of kinases known to phosphorylate class II HDACs.