Training the Next Generation of Data Monitoring Committee Members: An Initiative of the Heart Failure Collaboratory

Clinical trials are vital for assessing therapeutic interventions. The associated data monitoring committees (DMCs) safeguard patient interests and enhance trial integrity, thus promoting timely, reliable evaluations of those interventions. We face an urgent need to recruit and train new DMC members. The Heart Failure Collaboratory (HFC), a multidisciplinary public-private consortium of academics, trialists, patients, industry representatives, and government agencies, is working to improve the clinical trial ecosystem. The HFC aims to improve clinical trial efficiency and quality by standardizing concepts, and to help meet the demand for experienced individuals on DMCs by creating a standardized approach to training new members. This paper discusses the HFC's training workshop, and an apprenticeship model for new DMC members. It describes opportunities and challenges DMCs face, along with common myths and best practices learned through previous experiences, with an emphasis on data confidentiality and need for quality independent statistical reporting groups.

Left Ventricular Ejection Fraction and the Future of Heart Failure Phenotyping

Heart failure (HF) is a complex syndrome traditionally classified by left ventricular ejection fraction (LVEF) cutpoints. Although LVEF is prognostic for risk of events and predictive of response to some HF therapies, LVEF is a continuous variable and cutpoints are arbitrary, often based on historical clinical trial enrichment decisions rather than physiology. Holistic evaluation of the treatment effects for therapies throughout the LVEF range suggests the standard categorization paradigm for HF merits modification. The multidisciplinary Heart Failure Collaboratory reviewed data from large-scale HF clinical trials and found that many HF therapies have demonstrated therapeutic benefit across a large range of LVEF, but specific treatment effects vary across that range. Therefore, HF should practically be classified by association with an LVEF that is reduced or not reduced, while acknowledging uncertainty around the precise LVEF cutpoint, and future research should evaluate new therapies across the continuum of LVEF.

Dysregulated Autophagy and Sarcomere Dysfunction in Patients With Heart Failure With Co-Occurrence of P63A and P380S BAG3 Variants

BACKGROUND

Mutations to the co-chaperone protein BAG3 (B-cell lymphoma-2-associated athanogene-3) are a leading cause of dilated cardiomyopathy (DCM). These mutations often impact the C-terminal BAG domain (residues 420-499), which regulates heat shock protein 70-dependent protein turnover via autophagy. While mutations in other regions are less common, previous studies in patients with DCM found that co-occurrence of 2 BAG3 variants (P63A, P380S) led to worse prognosis. However, the underlying mechanism for dysfunction is not fully understood.

METHODS AND RESULTS

In this study, we used proteomics, Western blots, and myofilament functional assays on left ventricular tissue from patients with nonfailing, DCM, and DCM with BAG363/380 to determine how these mutations impact protein quality control and cardiomyocyte contractile function. We found dysregulated autophagy and increased protein ubiquitination in patients with BAG363/380 compared with nonfailing and DCM, suggesting impaired protein turnover. Expression and myofilament localization of BAG3-binding proteins were also uniquely altered in the BAG3,63/380 including abolished localization of the small heat shock protein CRYAB (alpha-crystallin B chain) to the sarcomere. To determine whether these variants impacted sarcomere function, we used cardiomyocyte force-calcium assays and found reduced maximal calcium-activated force in DCM and BAG363/380. Interestingly, myofilament calcium sensitivity was increased in DCM but not with BAG363/380, which was not explained by differences in troponin I phosphorylation.

CONCLUSIONS

Together, our data support that the disease-enhancing mechanism for BAG3 variants outside of the BAG domain is through disrupted protein turnover leading to compromised sarcomere function. These findings suggest a shared mechanism of disease among pathogenic BAG3 variants, regardless of location.

Assessment of Autophagy Markers Suggests Increased Activity Following LVAD Therapy

Left ventricular reverse remodeling in heart failure is associated with improved clinical outcomes. However, the molecular features that drive this process are poorly defined. Left ventricular assist devices (LVADs) are the therapy associated with the greatest reverse remodeling and lead to partial myocardial recovery in most patients. In this study, we examined whether autophagy may be implicated in post-LVAD reverse remodeling. We found expression of key autophagy factors increased post-LVAD, while autophagic substrates decreased. Autolysosome numbers increased post-LVAD, further indicating increased autophagy. These findings support the conclusion that mechanical unloading activates autophagy, which may underly the reverse remodeling observed.

An extensive β1-adrenergic receptor gene signaling network regulates molecular remodeling in dilated cardiomyopathies

We investigated the extent, biologic characterization, phenotypic specificity, and possible regulation of a β1-adrenergic receptor-linked (β1-AR-linked) gene signaling network (β1-GSN) involved in left ventricular (LV) eccentric pathologic remodeling. A 430-member β1-GSN was identified by mRNA expression in transgenic mice overexpressing human β1-ARs or from literature curation, which exhibited opposite directional behavior in interventricular septum endomyocardial biopsies taken from patients with beta-blocker-treated, reverse remodeled dilated cardiomyopathies. With reverse remodeling, the major biologic categories and percentage of the dominant directional change were as follows: metabolic (19.3%, 81% upregulated); gene regulation (14.9%, 78% upregulated); extracellular matrix/fibrosis (9.1%, 92% downregulated); and cell homeostasis (13.3%, 60% upregulated). Regarding the comparison of β1-GSN categories with expression from 19,243 nonnetwork genes, phenotypic selection for major β1-GSN categories was exhibited for LV end systolic volume (contractility measure), ejection fraction (remodeling index), and pulmonary wedge pressure (wall tension surrogate), beginning at 3 months and persisting to study completion at 12 months. In addition, 121 lncRNAs were identified as possibly involved in cis-acting regulation of β1-GSN members. We conclude that an extensive 430-member gene network downstream from the β1-AR is involved in pathologic ventricular remodeling, with metabolic genes as the most prevalent category.

Novel Tissue Factor Inhibition for Thromboprophylaxis in COVID-19: Primary Results of the ASPEN-COVID-19 Trial

BACKGROUND

Thrombo-inflammation is central to COVID-19-associated coagulopathy. TF (tissue factor), a driver disordered coagulation and inflammation in viral infections, may be a therapeutic target in COVID-19. The safety and efficacy of the novel TF inhibitor rNAPc2 (recombinant nematode anticoagulation protein c2) in COVID-19 are unknown.

METHODS

ASPEN-COVID-19 was an international, randomized, open-label, active comparator clinical trial with blinded end point adjudication. Hospitalized patients with COVID-19 and elevated D-dimer levels were randomized 1:1:2 to lower or higher dose rNAPc2 on days 1, 3, and 5 followed by heparin on day 8 or to heparin per local standard of care. In comparisons of the pooled rNAPc2 versus heparin groups, the primary safety end point was major or nonmajor clinically relevant International Society of Thrombosis and Haemostasis bleeding through day 8. The primary efficacy end point was proportional change in D-dimer concentration from baseline to day 8, or discharge if before day 8. Patients were followed for 30 days.

RESULTS

Among 160 randomized patients, median age was 54 years, 43.1% were female, and 38.8% had severe baseline COVID-19. There were no significant differences between rNAPc2 and heparin in bleeding or other safety events. Overall, median change in D-dimer was -16.8% (interquartile range, -45.7 to 36.8; P=0.41) with rNAPc2 treatment and -11.2% (-36.0 to 34.4; P=0.91) with heparin (P_intergroup=0.47). In prespecified analyses, in severely ill patients, D-dimer levels tended to increase more within the heparin (median, 29.0% [-14.9 to 145.2]; P=0.02) than the rNAPc2 group (median, 25.9% [-49.1 to 136.4]; P=0.14; P_intergroup=0.96); in mildly ill patients, D-dimer levels were reduced within each group with a numerically greater reduction with rNAPc2 versus heparin (rNAPc2 median, -32.7% [-44.7 to 4.3]; P=0.007 and heparin median, -16.8% [-36.0 to 0.5]; P=0.008, P_intergroup=0.34).

CONCLUSIONS

rNAPc2 treatment in hospitalized patients with COVID-19 was well tolerated without excess bleeding or serious adverse events but did not significantly reduce D-dimer more than heparin at day 8.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04655586.

Vaccination-Associated Myocarditis and Myocardial Injury

SARS-CoV-2 vaccine-associated myocarditis/myocardial injury should be evaluated in the contexts of COVID-19 infection, other types of viral myocarditis, and other vaccine-associated cardiac disorders. COVID-19 vaccine-associated myocardial injury can be caused by an inflammatory immune cell infiltrate, but other etiologies such as microvascular thrombosis are also possible. The clinical diagnosis is typically based on symptoms and cardiac magnetic resonance imaging. Endomyocardial biopsy is confirmatory for myocarditis, but may not show an inflammatory infiltrate because of rapid resolution or a non-inflammatory etiology. Myocarditis associated with SARS-COVID-19 vaccines occurs primarily with mRNA platform vaccines, which are also the most effective. In persons aged >16 or >12 years the myocarditis estimated crude incidences after the first 2 doses of BNT162b2 and mRNA-1273 are approximately 1.9 and 3.5 per 100 000 individuals, respectively. These rates equate to excess incidences above control populations of approximately 1.2 (BNT162b2) and 1.9 (mRNA-1273) per 100 000 persons, which are lower than the myocarditis rate for smallpox but higher than that for influenza vaccines. In the studies that have included mRNA vaccine and SARS-COVID-19 myocarditis measured by the same methodology, the incidence rate was increased by 3.5-fold over control in COVID-19 compared with 1.5-fold for BNT162b2 and 6.2-fold for mRNA-1273. However, mortality and major morbidity are less and recovery is faster with mRNA vaccine-associated myocarditis compared to COVID-19 infection. The reasons for this include vaccine-associated myocarditis having a higher incidence in young adults and adolescents, typically no involvement of other organs in vaccine-associated myocarditis, and based on comparisons to non-COVID viral myocarditis an inherently more benign clinical course.

Impact of Neuroeffector Adrenergic Receptor Polymorphisms on Incident Ventricular Fibrillation During Acute Myocardial Ischemia

Background Cardiac adrenergic receptor gene polymorphisms have the potential to influence risk of developing ventricular fibrillation (VF) during ST-segment-elevation myocardial infarction, but no previous study has comprehensively investigated those most likely to alter norepinephrine release, signal transduction, or biased signaling. Methods and Results In a case-control study, we recruited 953 patients with ST-segment-elevation myocardial infarction without previous cardiac history, 477 with primary VF, and 476 controls without VF, and genotyped them for ADRB1 Arg389Gly and Ser49Gly, ADRB2 Gln27Glu and Gly16Arg, and ADRA2C Ins322-325Del. Within each minor allele-containing genotype, haplotype, or 2-genotype combination, patients with incident VF were compared with non-VF controls by odds ratios (OR) of variant frequencies referenced against major allele homozygotes. Of 156 investigated genetic constructs, 19 (12.2%) exhibited significantly (P<0.05) reduced association with incident VF, and none was associated with increased VF risk except for ADRB1 Gly389 homozygotes in the subset of patients not receiving β-blockers. ADRB1 Gly49 carriers (prevalence 23.0%) had an OR (95% CI) of 0.70 (0.49-0.98), and the ADRA2C 322-325 deletion (Del) carriers (prevalence 13.5%) had an OR of 0.61 (0.39-0.94). When present in genotype combinations (8 each), both ADRB1 Gly49 carriers (OR, 0.67 [0.56-0.80]) and ADRA2C Del carriers (OR, 0.57 [0.45- 0.71]) were associated with reduced VF risk. Conclusions In ST-segment-elevation myocardial infarction, the adrenergic receptor minor alleles ADRB1 Gly49, whose encoded receptor undergoes enhanced agonist-mediated internalization and β-arrestin interactions leading to cardioprotective biased signaling, and ADRA2C Del322-325, whose receptor causes disinhibition of norepinephrine release, are associated with a lower incidence of VF. Registration URL: https://clinicaltrials.gov; Unique identifier: NCT00859300.

Myocardial Injury and Altered Gene Expression Associated With SARS-CoV-2 Infection or mRNA Vaccination

SARS CoV-2 enters host cells via its Spike protein moiety binding to the essential cardiac enzyme angiotensin-converting enzyme (ACE) 2, followed by internalization. COVID-19 mRNA vaccines are RNA sequences that are translated into Spike protein, which follows the same ACE2-binding route as the intact virion. In model systems, isolated Spike protein can produce cell damage and altered gene expression, and myocardial injury or myocarditis can occur during COVID-19 or after mRNA vaccination. We investigated 7 COVID-19 and 6 post-mRNA vaccination patients with myocardial injury and found nearly identical alterations in gene expression that would predispose to inflammation, coagulopathy, and myocardial dysfunction.

Inhibition of Eicosanoid Degradation Mitigates Fibrosis of the Heart

BACKGROUND

Organ fibrosis due to excessive production of extracellular matrix by resident fibroblasts is estimated to contribute to >45% of deaths in the Western world, including those due to cardiovascular diseases such as heart failure. Here, we screened for small molecule inhibitors with a common ability to suppress activation of fibroblasts across organ systems.

METHODS

High-content imaging of cultured cardiac, pulmonary, and renal fibroblasts was used to identify nontoxic compounds that blocked induction of markers of activation in response to the profibrotic stimulus, transforming growth factor-β1. SW033291, which inhibits the eicosanoid-degrading enzyme, 15-hydroxyprostaglandin dehydrogenase, was chosen for follow-up studies with cultured adult rat ventricular fibroblasts and human cardiac fibroblasts (CF), and for evaluation in mouse models of cardiac fibrosis and diastolic dysfunction. Additional mechanistic studies were performed with CFs treated with exogenous eicosanoids.

RESULTS

Nine compounds, including SW033291, shared a common ability to suppress transforming growth factor-β1-mediated activation of cardiac, pulmonary, and renal fibroblasts. SW033291 dose-dependently inhibited transforming growth factor-β1-induced expression of activation markers (eg, α-smooth muscle actin and periostin) in adult rat ventricular fibroblasts and normal human CFs, and reduced contractile capacity of the cells. Remarkably, the 15-hydroxyprostaglandin dehydrogenase inhibitor also reversed constitutive activation of fibroblasts obtained from explanted hearts from patients with heart failure. SW033291 blocked cardiac fibrosis induced by angiotensin II infusion and ameliorated diastolic dysfunction in an alternative model of systemic hypertension driven by combined uninephrectomy and deoxycorticosterone acetate administration. Mechanistically, SW033291-mediated stimulation of extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase signaling was required for the compound to block CF activation. Of the 12 exogenous eicosanoids that were tested, only 12(S)-hydroxyeicosatetraenoic acid, which signals through the G protein-coupled receptor, GPR31, recapitulated the suppressive effects of SW033291 on CF activation.

CONCLUSIONS

Inhibition of degradation of eicosanoids, arachidonic acid-derived fatty acids that signal through G protein-coupled receptors, is a potential therapeutic strategy for suppression of pathological organ fibrosis. In the heart, we propose that 15-hydroxyprostaglandin dehydrogenase inhibition triggers CF-derived autocrine/paracrine signaling by eicosanoids, including 12(S)-hydroxyeicosatetraenoic acid, to stimulate extracellular signal-regulated kinase 1/2 and block conversion of fibroblasts into activated cells that secrete excessive amounts of extracellular matrix and contribute to heart failure pathogenesis.

Cardiomyocyte-Specific Long Noncoding RNA Regulates Alternative Splicing of the Triadin Gene in the Heart

BACKGROUND

Abnormalities in Ca2+ homeostasis are associated with cardiac arrhythmias and heart failure. Triadin plays an important role in Ca2+ homeostasis in cardiomyocytes. Alternative splicing of a single triadin gene produces multiple triadin isoforms. The cardiac-predominant isoform, mouse MT-1 or human Trisk32, is encoded by triadin exons 1 to 8. In humans, mutations in the triadin gene that lead to a reduction in Trisk32 levels in the heart can cause cardiac dysfunction and arrhythmias. Decreased levels of Trisk32 in the heart are also common in patients with heart failure. However, mechanisms that maintain triadin isoform composition in the heart remain elusive.

METHODS

We analyzed triadin expression in heart explants from patients with heart failure and cardiac arrhythmias and in hearts from mice carrying a knockout allele for Trdn-as, a cardiomyocyte-specific long noncoding RNA encoded by the antisense strand of the triadin gene, between exons 9 and 11. Catecholamine challenge with isoproterenol was performed on Trdn-as knockout mice to assess the role of Trdn-as in cardiac arrhythmogenesis, as assessed by ECG. Ca2+ transients in adult mouse cardiomyocytes were measured with the IonOptix platform or the GCaMP system. Biochemistry assays, single-molecule fluorescence in situ hybridization, subcellular localization imaging, RNA sequencing, and molecular rescue assays were used to investigate the mechanisms by which Trdn-as regulates cardiac function and triadin levels in the heart.

RESULTS

We report that Trdn-as maintains cardiac function, at least in part, by regulating alternative splicing of the triadin gene. Knockout of Trdn-as in mice downregulates cardiac triadin, impairs Ca2+ handling, and causes premature death. Trdn-as knockout mice are susceptible to cardiac arrhythmias in response to catecholamine challenge. Normalization of cardiac triadin levels in Trdn-as knockout cardiomyocytes is sufficient to restore Ca2+ handling. Last, Trdn-as colocalizes and interacts with serine/arginine splicing factors in cardiomyocyte nuclei and is essential for efficient recruitment of splicing factors to triadin precursor mRNA.

CONCLUSIONS

These findings reveal regulation of alternative splicing as a novel mechanism by which a long noncoding RNA controls cardiac function. This study indicates potential therapeutics for heart disease by targeting the long noncoding RNA or pathways regulating alternative splicing.

Integrated analysis of miRNA-mRNA interaction in pediatric dilated cardiomyopathy

BACKGROUND

MicroRNAs (miRNAs) are short single-stranded nucleotides that can regulate gene expression. Although we previously evaluated the expression of miRNAs in pediatric dilated cardiomyopathy (DCM) by miRNA array, pathway prediction based on changes in mRNA expression has not been previously analyzed in this population. The current study aimed to determine the regulation of miRNA expression by miRNA-sequencing (miRNA-seq) and, through miRNA-sequencing (mRNA-seq), analyze their putative target genes and altered pathways in pediatric DCM hearts.

METHODS

miRNA expression was determined by miRNA-seq [n = 10 non-failing (NF), n = 20 DCM]. Expression of a subset of miRNAs was evaluated in adult DCM patients (n = 11 NF, n = 13 DCM). miRNA-mRNA prediction analysis was performed using mRNA-seq data (n = 7 NF, n = 7 DCM) from matched samples.

RESULTS

Expression of 393 miRNAs was significantly different (p < 0.05) in pediatric DCM patients compared to NF controls. TargetScan-based miRNA-mRNA analysis revealed 808 significantly inversely expressed genes. Functional analysis suggests upregulated pathways related to the regulation of stem cell differentiation and cardiac muscle contraction, and downregulated pathways related to the regulation of protein phosphorylation, signal transduction, and cell communication.

CONCLUSIONS

Our results demonstrated a unique age-dependent regulation of miRNAs and their putative target genes, which may contribute to distinctive phenotypic characteristics of DCM in children.

IMPACT

This is the first study to compare miRNA expression in the heart of pediatric DCM patients to age-matched healthy controls by RNA sequencing. Expression of a subset of miRNAs is uniquely dysregulated in children. Using mRNA-seq and miRNA-seq from matched samples, target prediction was performed. This study underscores the importance of pediatric-focused studies.

The Effect of Cardiac Resynchronization without a Defibrillator on Morbidity and Mortality: An Individual-Patient-Data Meta-Analysis of COMPANION and CARE-HF

BACKGROUND

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality for patients with heart failure, reduced left ventricular ejection fraction, QRS duration >130 ms and in sinus rhythm.

OBJECTIVES

To identify patient-characteristics that predict the effect, specifically, of CRT-pacemakers (CRT-P) on all-cause mortality or the composite of hospitalisation for heart failure or all-cause mortality.

METHODS

An individual patient-data meta-analysis of the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) and Cardiac Resynchronization - Heart Failure (CARE-HF) trials. Only patients assigned to CRT-P or control (n = 1738) were included in order to avoid confounding from concomitant defibrillator therapy. The influence of baseline characteristics on treatment effects was investigated.

RESULTS

Median age was 67 (59-73) years, most patients were men (70%), 68% had a QRS duration of 150-199 ms and 80% had left bundle branch block (LBBB). Patients assigned to CRT-P had lower rates for all-cause mortality (HR 0.68 (95% CI 0.56 to 0.81; p < 0.0001) and the composite outcome (HR 0.67 (95% CI 0.58 to 0.78; p < 0.0001). No pre-specified characteristic, including sex, aetiology of ventricular dysfunction, QRS duration (within the studied range) or morphology or PR interval significantly influenced the effect of CRT-P on all-cause mortality or the composite outcome. However, CRT-P had a greater effect on the composite outcome for patients with lower body surface area (BSA) and those prescribed beta-blockers.

CONCLUSIONS

CRT-P reduces morbidity and mortality in appropriately selected patients with heart failure. Benefits may be greater in smaller patients and in those receiving beta-blockers. Neither QRS duration nor morphology independently predicted the benefit of CRT-P.

Rationale and design of a study to assess the safety and efficacy of rNAPc2 in COVID-19: the Phase 2b ASPEN-COVID-19 trial

Background

The interaction between thrombosis and inflammation appears central to COVID-19-associated coagulopathy and likely contributes to poor outcomes. Tissue factor is a driver of disordered coagulation and inflammatory signaling in viral infections and is important for viral replication; therefore, tissue factor may be an important therapeutic target in COVID-19.

Study Design

ASPEN-COVID-19 (NCT04655586) is a randomized, prospective open-label blinded endpoint (PROBE), active comparator Phase 2b trial to evaluate the safety and efficacy of recombinant Nematode Anticoagulant Protein c2 (rNAPc2), a potent tissue factor inhibitor, in patients hospitalized with COVID-19 with elevated D-dimer levels. This report describes the design of the Phase 2b dose ranging and proof of concept study. Participants are randomly assigned, in a 1:1:2 ratio, to lower or higher dose rNAPc2 by subcutaneous injection on days 1, 3, and 5 or to heparin according to local standard of care; randomization is stratified by baseline D-dimer level (at 2X upper limit of normal). The primary efficacy endpoint for Phase 2b is proportional change in D-dimer concentration from baseline to Day 8 or day of discharge, whichever is earlier. The primary safety endpoint is major or non-major clinically relevant bleeding through Day 8. Phase 2b enrollment began in December 2020 and is projected to complete ∼160 participants by Q4 2021.

Conclusions

ASPEN-COVID-19 will provide important data on a novel therapeutic approach that may improve outcomes in hospitalized COVID-19 patients beyond available anticoagulants by targeting tissue factor, with potential effects on not only thrombosis but also inflammation and viral propagation.

Activation of PDGFRA signaling contributes to filamin C-related arrhythmogenic cardiomyopathy

FLNC truncating mutations (FLNCtv) are prevalent causes of inherited dilated cardiomyopathy (DCM), with a high risk of developing arrhythmogenic cardiomyopathy. We investigated the molecular mechanisms of mutant FLNC in the pathogenesis of arrhythmogenic DCM (a-DCM) using patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). We demonstrated that iPSC-CMs from two patients with different FLNCtv mutations displayed arrhythmias and impaired contraction. FLNC ablation induced a similar phenotype, suggesting that FLNCtv are loss-of-function mutations. Coimmunoprecipitation and proteomic analysis identified β-catenin (CTNNB1) as a downstream target. FLNC deficiency induced nuclear translocation of CTNNB1 and subsequently activated the platelet-derived growth factor receptor alpha (PDGFRA) pathway, which were also observed in human hearts with a-DCM and FLNCtv. Treatment with the PDGFRA inhibitor, crenolanib, improved contractile function of patient iPSC-CMs. Collectively, our findings suggest that PDGFRA signaling is implicated in the pathogenesis, and inhibition of this pathway is a potential therapeutic strategy in FLNC-related cardiomyopathies.

lncExACT1 and DCHS2 Regulate Physiological and Pathological Cardiac Growth

BACKGROUND

The heart grows in response to pathological and physiological stimuli. The former often precedes cardiomyocyte loss and heart failure; the latter paradoxically protects the heart and enhances cardiomyogenesis. The mechanisms underlying these differences remain incompletely understood. While long noncoding RNAs (lncRNAs) are important in cardiac development and disease, less is known about their roles in physiological hypertrophy or cardiomyogenesis.

METHODS

RNA sequencing was applied to hearts from mice after eight weeks voluntary exercise-induced physiological hypertrophy and cardiomyogenesis or transverse aortic constriction (TAC) for two or eight weeks to induce pathological hypertrophy or heart failure. The top lncRNA candidate was overexpressed in hearts with adeno-associated virus (AAV) vectors and inhibited with antisense locked nucleic acid (LNA)-GapmeRs to examine its function. Downstream effectors were identified through promoter analyses and binding assays. The functional roles of a novel downstream effector, dachsous cadherin-related 2 (DCHS2), were examined through transgenic overexpression in zebrafish and cardiac-specific deletion in Cas9-knockin mice.

RESULTS

We identified exercise-regulated cardiac lncRNAs, termed lncExACTs. lncExACT1 was evolutionarily conserved and decreased in exercised hearts but increased in human and experimental heart failure. Cardiac lncExACT1 overexpression caused pathological hypertrophy and heart failure, while lncExACT1 inhibition induced physiological hypertrophy and cardiomyogenesis, protecting against cardiac fibrosis and dysfunction. lncExACT1 functioned by regulating microRNA-222, calcineurin signaling, and Hippo/Yap1 signaling through DCHS2. Cardiomyocyte DCHS2 overexpression in zebrafish induced pathological hypertrophy and impaired cardiac regeneration, promoting scarring after injury. In contrast, murine DCHS2 deletion induced physiological hypertrophy and promoted cardiomyogenesis.

CONCLUSIONS

These studies identify lncExACT1-DCHS2 as a novel pathway regulating cardiac hypertrophy and cardiomyogenesis. lncExACT1-DCHS2 acts as a master switch toggling the heart between physiological and pathological growth to determine functional outcomes, providing a potentially tractable therapeutic target for harnessing the beneficial effects of exercise.

An LMNA synonymous variant associated with severe dilated cardiomyopathy: Case report

Dilated cardiomyopathy (DCM) is one of the most common cardiac phenotypes caused by mutations of lamin A/C (LMNA) gene in humans. In our study, a cohort of 57 patients who underwent heart transplant for dilated cardiomyopathy was screened for variants in LMNA. We identified a synonymous variant c.936G>A in the last nucleotide of exon 5 of LMNA in a DCM family. Clinically, the LMNA variant carriers presented with severe familial DCM, conduction disease, and high creatine-kinase level. The LMNA c.936G>A variant is novel and has not been reported in current genetic variant databases. Sanger sequencing results showed the presence of LMNA c.936G>A variant in the genomic DNA but not in the cDNA derived from one family member's heart tissue. Real-time quantitative polymerase chain reaction showed significantly lower LMNA mRNA levels in the patient's heart compared to the controls, suggesting that the c.936G>A LMNA variant resulted in reduced mRNA and possibly lower protein expression of LMNA. These findings expand the understanding on the association between synonymous variant of LMNA and the molecular pathogenesis in DCM patients.

Serum response factor deletion 5 regulates phospholamban phosphorylation and calcium uptake

AIMS

Pediatric dilated cardiomyopathy (pDCM) is characterized by unique age-dependent molecular mechanisms that include myocellular responses to therapy. We previously showed that pDCM, but not adult DCM patients respond to phosphodiesterase 3 inhibitors (PDE3i) by increasing levels of the second messenger cAMP and consequent phosphorylation of phospholamban (PLN). However, the molecular mechanisms involved in the differential pediatric and adult response to PDE3i are not clear.

METHODS AND RESULTS

Quantification of serum response factor (SRF) isoforms from the left ventricle of explanted hearts showed that PDE3i treatment affects expression of SRF isoforms in pDCM hearts. An SRF isoform lacking exon 5 (SRFdel5) was highly expressed in the hearts of pediatric, but not adult DCM patients treated with PDE3i. To determine the functional consequence of expression of SRFdel5, we overexpressed full length SRF or SRFdel5 in cultured cardiomyocytes with and without adrenergic stimulation. Compared to a control adenovirus, expression of SRFdel5 increased phosphorylation of PLN, negatively affected expression of the phosphatase that promotes dephosphorylation of PLN (PP2Cε), and promoted faster calcium reuptake, whereas expression of full length SRF attenuated calcium reuptake through blunted phosphorylation of PLN.

CONCLUSIONS

Taken together, these data indicate that expression of SRFdel5 in pDCM hearts in response to PDE3i contributes to improved function through regulating PLN phosphorylation and thereby calcium reuptake.

Bucindolol Decreases Atrial Fibrillation Burden in Patients With Heart Failure and the ADRB1 Arg389Arg Genotype

[Figure: see text].

Diagnosis and Treatment of Right Heart Failure in Pulmonary Vascular Diseases: A National Heart, Lung, and Blood Institute Workshop

Right ventricular dysfunction is a hallmark of advanced pulmonary vascular, lung parenchymal, and left heart disease, yet the underlying mechanisms that govern (mal)adaptation remain incompletely characterized. Owing to the knowledge gaps in our understanding of the right ventricle (RV) in health and disease, the National Heart, Lung, and Blood Institute (NHLBI) commissioned a working group to identify current challenges in the field. These included a need to define and standardize normal RV structure and function in populations; access to RV tissue for research purposes and the development of complex experimental platforms that recapitulate the in vivo environment; and the advancement of imaging and invasive methodologies to study the RV within basic, translational, and clinical research programs. Specific recommendations were provided, including a call to incorporate precision medicine and innovations in prognosis, diagnosis, and novel RV therapeutics for patients with pulmonary vascular disease.

Abstract 079: Nebivolol Associated With Reduced Incident Cardiovascular Events In Hypertensive Patients Compared With Non-vasodilatory Beta Blockers

Introduction: Beta blockers are not guideline-recommended first-line agents for hypertension, based on evidence that older generation beta blockers such as atenolol are associated with inferior reduction of some cardiovascular events compared to other antihypertensive classes. Vasodilatory beta blockers such as nebivolol have been found to have beneficial effects on peripheral vasculature through nitric oxide, endothelin-1, and tissue plasminogen activator pathways. The objective of this study is to compare longitudinal cardiovascular outcomes of hypertensive patients taking the vasodilatory beta blocker nebivolol with hypertensive patients taking the non-vasodilatory beta blockers atenolol and metoprolol.

Hypothesis: Nebivolol will be associated with a reduction in odds of adverse cardiovascular outcomes compared with non-vasodilatory beta blockers.

Methods: The study is a retrospective cohort analysis of de-identified data from adults in the University of Colorado health system with hypertension and on the vasodilatory beta blocker nebivolol or the non-vasodilatory beta blockers atenolol or metoprolol, without preceding diagnosis of cardiovascular or cerebrovascular disease. The primary outcome is incident cardiovascular hospitalization or diagnosis of cardiovascular event including heart failure, stroke, myocardial infarction, angina pectoris, or coronary revascularization based on diagnosis or procedure codes. Nearest-available propensity matching logistic regression was used, with each patient taking nebivolol matched to two control patients taking a non-vasodilatory beta blocker. Propensity matching variables included baseline demographics, cardiovascular risk factors, Charlson comorbidity index, other cardiovascular medications, and duration of follow-up.

Results: There were 1395 patients taking nebivolol, and 20208 patients taking atenolol or metoprolol. Patients were predominantly female (54%, 11681 of 21603) and non-Hispanic white (75%, 16185 of 21603), with mean age of 60. The primary outcome occurred in 19% (259 of 1395) of those taking nebivolol, 29% (1891 of 6527) of those taking atenolol, and 40% (5500 of 13681) of those taking metoprolol. In propensity matched logistic regression, nebivolol is associated with reduced odds of incident cardiovascular events when compared to the non-vasodilatory beta blockers atenolol and metoprolol (OR 0.33, 95% CI 0.28 to 0.40). This association was also found with individual comparison with atenolol (OR 0.47, 95% CI 0.39 to 0.57) and metoprolol (OR 0.26, 95% CI 0.21 to 0.32).

Conclusions: The vasodilatory beta blocker nebivolol is associated with reduced odds of incident cardiovascular events compared to non-vasodilatory beta blockers. Additional study of other beta blockers is necessary to determine if this is a vasodilatory beta blocker class effect, or is specific to nebivolol.

The Addition of a Defibrillator to Resynchronization Therapy Decreases Mortality in Patients With Nonischemic Cardiomyopathy

OBJECTIVES

The aim of this study was to determine whether patients with heart failure with reduced ejection fraction (HFrEF) due to nonischemic etiology eligible for cardiac resynchronization therapy (CRT) benefit from an implantable cardioverter-defibrillator (ICD).

BACKGROUND

It is uncertain whether CRT with an ICD (CRT-D) compared to without an ICD (CRT-P) is associated with a survival benefit in patients with nonischemic etiologies of HFrEF.

METHODS

Analyses of the COMPANION (Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure) trial were performed, using Cox proportional hazards modeling stratified by HFrEF etiology of nonischemic cardiomyopathy (NICM) or ischemic cardiomyopathy (ICM). The primary outcome was all-cause mortality (ACM), and secondary outcomes were the combination of cardiovascular mortality or heart failure hospitalization and sudden cardiac death.

RESULTS

Among patients randomized to CRT (n = 1,212), 236 (19.5%) died, 131 and 105 in the CRT-P and CRT-D arms, respectively. The unadjusted and adjusted hazard ratios (HRs) for CRT-D versus CRT-P were both 0.84 (95% confidence interval [CI]: 0.65 to 1.09) for ACM, with a significant device-etiology interaction (p_interaction = 0.015 adjusted; p_interaction = 0.040 unadjusted). In patients with NICM (n = 555), CRT-D versus CRT-P was associated with reduced ACM (adjusted HR: 0.54; 95% CI: 0.34 to 0.86), while patients with ICM (n = 657) did not exhibit a between-device reduction in ACM (adjusted HR: 1.05; 95% CI: 0.77 to 1.44). The effects of CRT-D versus CRT-P on sudden cardiac death (advantage CRT-D) and cardiovascular mortality or heart failure hospitalization (no difference between CRT-P and CRT-D) were similar between the 2 HFrEF etiologies.

CONCLUSIONS

COMPANION patients with NICM exhibited a decrease in ACM associated with CRT-D but not CRT-P treatment, whereas patients with ICM did not.

COVID-19 and Cardiovascular Disease: From Bench to Bedside

A pandemic of historic impact, coronavirus disease 2019 (COVID-19) has potential consequences on the cardiovascular health of millions of people who survive infection worldwide. Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), the etiologic agent of COVID-19, can infect the heart, vascular tissues, and circulating cells through ACE2 (angiotensin-converting enzyme 2), the host cell receptor for the viral spike protein. Acute cardiac injury is a common extrapulmonary manifestation of COVID-19 with potential chronic consequences. This update provides a review of the clinical manifestations of cardiovascular involvement, potential direct SARS-CoV-2 and indirect immune response mechanisms impacting the cardiovascular system, and implications for the management of patients after recovery from acute COVID-19 infection.

Maturation of Pluripotent Stem Cell-Derived Cardiomyocytes Enables Modeling of Human Hypertrophic Cardiomyopathy

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a powerful platform for biomedical research. However, they are immature, which is a barrier to modeling adult-onset cardiovascular disease. Here, we sought to develop a simple method that could drive cultured hiPSC-CMs toward maturity across a number of phenotypes, with the aim of utilizing mature hiPSC-CMs to model human cardiovascular disease. hiPSC-CMs were cultured in fatty acid-based medium and plated on micropatterned surfaces. These cells display many characteristics of adult human cardiomyocytes, including elongated cell morphology, sarcomeric maturity, and increased myofibril contractile force. In addition, mature hiPSC-CMs develop pathological hypertrophy, with associated myofibril relaxation defects, in response to either a pro-hypertrophic agent or genetic mutations. The more mature hiPSC-CMs produced by these methods could serve as a useful in vitro platform for characterizing cardiovascular disease.

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Standard (glucose) cultured hiPSC-CMs demonstrate a blunted hypertrophic response

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A maturation method induces hiPSC-CM maturation and suppresses HIF1A expression

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Mature hiPSC-CMs demonstrate improved sarcomeric morphology and contractility

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Mature hiPSC-CMs respond to agonist- or mutation-induced hypertrophy

Dynamic Regulation of SARS-Cov-2 Binding and Cell Entry Mechanisms in Remodeled Human Ventricular Myocardium

Using serial analysis of myocardial gene expression employing endomyocardial biopsy starting material in a dilated cardiomyopathy cohort, we show that mRNA expression of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) cardiac myocyte receptor ACE2 is up-regulated with remodeling and with reverse remodeling down-regulates into the normal range. The proteases responsible for virus-cell membrane fusion were expressed but not regulated with remodeling. In addition, a new candidate for SARS-CoV-2 cell binding and entry was identified, the integrin encoded by ITGA5. Up-regulation in ACE2 in remodeled left ventricles may explain worse outcomes in patients with coronavirus disease 2019 who have underlying myocardial disorders, and counteracting ACE2 up-regulation is a possible therapeutic approach to minimizing cardiac damage.

Transcriptome signature of ventricular arrhythmia in dilated cardiomyopathy reveals increased fibrosis and activated TP53

AIMS

One-third of DCM patients experience ventricular tachycardia (VT), but a clear biological basis for this has not been established. The purpose of this study was to identify transcriptome signatures and enriched pathways in the hearts of dilated cardiomyopathy (DCM) patients with VT.

METHODS AND RESULTS

We used RNA-sequencing in explanted heart tissue from 49 samples: 19 DCM patients with VT, 16 DCM patients without VT, and 14 non-failing controls. We compared each DCM cohort to the controls and identified the genes that were differentially expressed in DCM patients with VT but not without VT. Differentially expressed genes were evaluated using pathway analysis, and pathways of interest were investigated by qRT-PCR validation, Western blot, and microscopy. There were 590 genes differentially expressed in DCM patients with VT that are not differentially expressed in patients without VT. These genes were enriched for genes in the TGFß1 and TP53 signaling pathways. Increased fibrosis and activated TP53 signaling was demonstrated in heart tissue of DCM patients with VT.

CONCLUSIONS

Our study supports that distinct biological mechanisms distinguish ventricular arrhythmia in DCM patients.

A PDE3A Promoter Polymorphism Regulates cAMP-Induced Transcriptional Activity in Failing Human Myocardium

BACKGROUND

The phosphodiesterase 3A (PDE3A) gene encodes a PDE that regulates cardiac myocyte cyclic adenosine monophosphate (cAMP) levels and myocardial contractile function. PDE3 inhibitors (PDE3i) are used for short-term treatment of refractory heart failure (HF), but do not produce uniform long-term benefit.

OBJECTIVES

The authors tested the hypothesis that drug target genetic variation could explain clinical response heterogeneity to PDE3i in HF.

METHODS

PDE3A promoter studies were performed in a cloned luciferase construct. In human left ventricular (LV) preparations, mRNA expression was measured by reverse transcription polymerase chain reaction, and PDE3 enzyme activity by cAMP-hydrolysis.

RESULTS

The authors identified a 29-nucleotide (nt) insertion (INS)/deletion (DEL) polymorphism in the human PDE3A gene promoter beginning 2,214 nt upstream from the PDE3A1 translation start site. Transcription factor ATF3 binds to the INS and represses cAMP-dependent promoter activity. In explanted failing LVs that were homozygous for PDE3A DEL and had been treated with PDE3i pre-cardiac transplantation, PDE3A1 mRNA abundance and microsomal PDE3 enzyme activity were increased by 1.7-fold to 1.8-fold (p < 0.05) compared with DEL homozygotes not receiving PDE3i. The basis for the selective up-regulation in PDE3A gene expression in DEL homozygotes treated with PDE3i was a cAMP response element enhancer 61 nt downstream from the INS, which was repressed by INS. The DEL homozygous genotype frequency was also enriched in patients with HF.

CONCLUSIONS

A 29-nt INS/DEL polymorphism in the PDE3A promoter regulates cAMP-induced PDE3A gene expression in patients treated with PDE3i. This molecular mechanism may explain response heterogeneity to this drug class, and may inform a pharmacogenetic strategy for a more effective use of PDE3i in HF.

Association of Variants in BAG3 With Cardiomyopathy Outcomes in African American Individuals

Importance

The prevalence of nonischemic dilated cardiomyopathy (DCM) is greater in individuals of African ancestry than in individuals of European ancestry. However, little is known about whether the difference in prevalence or outcomes is associated with functional genetic variants.

Objective

We hypothesized that Bcl2-associated anthanogene 3 (BAG3) genetic variants were associated with outcomes in individuals of African ancestry with DCM.

Design

This multicohort study of the BAG3 genotype in patients of African ancestry with dilated cardiomyopathy uses DNA obtained from African American individuals enrolled in 3 clinical studies: the Genetic Risk Assessment of African Americans With Heart Failure (GRAHF) study; the Intervention in Myocarditis and Acute Cardiomyopathy Trial-2 (IMAC-2) study; and the Genetic Risk Assessment of Cardiac Events (GRACE) study. Samples of DNA were also acquired from the left ventricular myocardium of patients of African ancestry who underwent heart transplant at the University of Colorado and University of Pittsburgh.

Main Outcomes and Measures

The primary end points were the prevalence of BAG3 mutations in African American individuals and event-free survival in participants harboring functional BAG3 mutations.

Results

Four BAG3 genetic variants were identified; these were expressed in 42 of 402 African American individuals (10.4%) with nonischemic heart failure and 9 of 107 African American individuals (8.4%) with ischemic heart failure but were not present in a reference population of European ancestry (P < .001). The variants included 2 nonsynonymous single-nucleotide variants; 1 three-nucleotide in-frame insertion; and 2 single-nucleotide variants that were linked in cis. The presence of BAG3 variants was associated with a nearly 2-fold (hazard ratio, 1.97 [95% CI, 1.19-3.24]; P = .01) increase in cardiac events in carriers compared with noncarriers. Transfection of transformed adult human ventricular myocytes with plasmids expressing the 4 variants demonstrated that each variant caused an increase in apoptosis and a decrease in autophagy when samples were subjected to the stress of hypoxia-reoxygenation.

Conclusions and Relevance

This study demonstrates that genetic variants in BAG3 found almost exclusively in individuals of African ancestry were not causative of disease but were associated with a negative outcome in patients with a dilated cardiomyopathy through modulation of the function of BAG3. The results emphasize the importance of biological differences in causing phenotypic variance across diverse patient populations, the need to include diverse populations in genetic cohorts, and the importance of determining the pathogenicity of genetic variants.

Sequential analysis of myocardial gene expression with phenotypic change: Use of cross-platform concordance to strengthen biologic relevance

Objectives

To investigate the biologic relevance of cross-platform concordant changes in gene expression in intact human failing/hypertrophied ventricular myocardium undergoing reverse remodeling.

Background

Information is lacking on genes and networks involved in remodeled human LVs, and in the associated investigative best practices.

Methods

We measured mRNA expression in ventricular septal endomyocardial biopsies from 47 idiopathic dilated cardiomyopathy patients, at baseline and after 3–12 months of β-blocker treatment to effect left ventricular (LV) reverse remodeling as measured by ejection fraction (LVEF). Cross-platform gene expression change concordance was investigated in reverse remodeling Responders (R) and Nonresponders (NR) using 3 platforms (RT-qPCR, microarray, and RNA-Seq) and two cohorts (All 47 subjects (A-S) and a 12 patient “Super-Responder” (S-R) subset of A-S).

Results

For 50 prespecified candidate genes, in A-S mRNA expression 2 platform concordance (C_cpT), but not single platform change, was directly related to reverse remodeling, indicating C_cpT has biologic significance. Candidate genes yielded a C_cpT (PCR/microarray) of 62% for Responder vs. Nonresponder (R/NR) change from baseline analysis in A-S, and ranged from 38% to 100% in S-R for PCR/microarray/RNA-Seq 2 platform comparisons. Global gene C_cpT measured by microarray/RNA-Seq was less than for candidate genes, in S-R R/NR 17.5% vs. 38% (P = 0.036). For S-R global gene expression changes, both cross-cohort concordance (C_ccT) and C_cpT yielded markedly greater values for an R/NR vs. an R-only analysis (by 22 fold for C_ccT and 7 fold for C_cpT). Pathway analysis of concordant global changes for R/NR in S-R revealed signals for downregulation of multiple phosphoinositide canonical pathways, plus expected evidence of a β₁-adrenergic receptor gene network including enhanced Ca²⁺ signaling.

Conclusions

Two-platform concordant change in candidate gene expression is associated with LV biologic effects, and global expression concordant changes are best identified in an R/NR design that can yield novel information.

Bucindolol for the Maintenance of Sinus Rhythm in a Genotype-Defined HF Population: The GENETIC-AF Trial

OBJECTIVES

The purpose of this study was to compare the effectiveness of bucindolol with that of metoprolol succinate for the maintenance of sinus rhythm in a genetically defined heart failure (HF) population with atrial fibrillation (AF).

BACKGROUND

Bucindolol is a beta-blocker whose unique pharmacologic properties provide greater benefit in HF patients with reduced ejection fraction (HFrEF) who have the beta₁-adrenergic receptor (ADRB1) Arg389Arg genotype.

METHODS

A total of 267 HFrEF patients with a left ventricular ejection fraction (LVEF) <0.50, symptomatic AF, and the ADRB1 Arg389Arg genotype were randomized 1:1 to receive bucindolol or metoprolol therapy and were up-titrated to target doses. The primary endpoint of AF or atrial flutter (AFL) or all-cause mortality (ACM) was evaluated by electrocardiogram (ECG) during a 24-week period.

RESULTS

The hazard ratio (HR) for the primary endpoint was 1.01 (95% confidence interval [CI]: 0.71 to 1.42), but trends for bucindolol benefit were observed in several subgroups. Precision therapeutic phenotyping revealed that a differential response to bucindolol was associated with the interval of time from the initial diagnoses of AF and HF to randomization and with the onset of AF relative to that of the initial HF diagnosis. In a cohort whose first AF and HF diagnoses were <12 years prior to randomization, in which AF onset did not precede HF by more than 2 years (n = 196), the HR was 0.54 (95% CI: 0.33 to 0.87; p = 0.011).

CONCLUSIONS

Pharmacogenetically guided bucindolol therapy did not reduce the recurrence of AF/AFL or ACM compared to that of metoprolol therapy in HFrEF patients, but populations were identified who merited further investigation in future phase 3 trials.

Transcriptome analysis of human heart failure reveals dysregulated cell adhesion in dilated cardiomyopathy and activated immune pathways in ischemic heart failure

Background

Current heart failure (HF) treatment is based on targeting symptoms and left ventricle dysfunction severity, relying on a common HF pathway paradigm to justify common treatments for HF patients. This common strategy may belie an incomplete understanding of heterogeneous underlying mechanisms and could be a barrier to more precise treatments. We hypothesized we could use RNA-sequencing (RNA-seq) in human heart tissue to delineate HF etiology-specific gene expression signatures.

Results

RNA-seq from 64 human left ventricular samples: 37 dilated (DCM), 13 ischemic (ICM), and 14 non-failing (NF). Using a multi-analytic approach including covariate adjustment for age and sex, differentially expressed genes (DEGs) were identified characterizing HF and disease-specific expression. Pathway analysis investigated enrichment for biologically relevant pathways and functions. DCM vs NF and ICM vs NF had shared HF-DEGs that were enriched for the fetal gene program and mitochondrial dysfunction. DCM-specific DEGs were enriched for cell-cell and cell-matrix adhesion pathways. ICM-specific DEGs were enriched for cytoskeletal and immune pathway activation. Using the ICM and DCM DEG signatures from our data we were able to correctly classify the phenotypes of 24/31 ICM and 32/36 DCM samples from publicly available replication datasets.

Conclusions

Our results demonstrate the commonality of mitochondrial dysfunction in end-stage HF but more importantly reveal key etiology-specific signatures. Dysfunctional cell-cell and cell-matrix adhesion signatures typified DCM whereas signals related to immune and fibrotic responses were seen in ICM. These findings suggest that transcriptome signatures may distinguish end-stage heart failure, shedding light on underlying biological differences between ICM and DCM.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5213-9) contains supplementary material, which is available to authorized users.

Dose Response of β-Blockers in Adrenergic Receptor Polymorphism Genotypes

Background In heart failure (HF) with reduced ejection fraction, 2 clinical trials, the BEST (β-Blocker Evaluation of Survival Trial) and HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training), have reported an effectiveness interaction between the ADRB1 (β-1 adrenergic receptor) Arg389Gly polymorphism and β-blockers (BBs). HF-ACTION additionally reported a dose-related interaction of unclear origin. If confirmed and pharmacogenetically resolved, these findings may have important implications for HF with reduced ejection fraction precision therapy. We used uniform methodology to investigate BB dose-ADRB1 Arg389Gly polymorphism interaction with major clinical end points in BEST/bucindolol and HF-ACTION/other BB databases. Methods This was a retrospective analysis of prospectively designed DNA substudies from BEST (N=1040) and HF-ACTION (N=957). Subjects were genotyped for ADRB1 Arg389Gly and ADRA2C (α2C adrenergic receptor) Ins322-325Del. BB dose was defined as either no/low dose or high dose, according to total daily dose of either bucindolol (BEST subjects) or other BB (HF-ACTION subjects) standardized to carvedilol equivalents. The main outcome of interest was all-cause mortality, and CV mortality/HF hospitalization was a secondary outcome. Results Subjects in each trial had less all-cause mortality with high- versus no/low-dose BB if they had ADRB1 Arg389Arg (BEST: hazard ratio [HR]=0.40, P=0.002; HF-ACTION: HR=0.45, P=0.005) but not Arg389Gly genotype (both P>0.2). Among gene-dose groups, there was a differential favorable treatment effect of 46% for high-dose bucindolol with ADRB1 Arg389Arg versus Gly carrier genotype (HR, 0.54; P=0.018), but not for no/low-dose bucindolol. In contrast, HF-ACTION Arg389Arg genotype subjects taking no/low-dose BB had greater all-cause mortality compared with 389Gly carriers (HR, 1.83; P=0.015), whereas all-cause mortality did not vary by genotype among subjects taking high-dose BB (HR, 0.84; P=0.55). Conclusions The enhanced HF with reduced ejection fraction efficacy of bucindolol in the ADRB1 Arg389Arg versus 389Gly carrier genotypes occurs at high dose. Other BBs taken at low dose have reduced efficacy for Arg389Arg genotype subjects compared with 389Gly carriers, suggesting a greater relative treatment effect at high dose. These data support guideline recommendations to use high, clinical trial target doses of all BBs to treat HF with reduced ejection fraction.

Structural and Functional Phenotyping of the Failing Heart: Is the Left Ventricular Ejection Fraction Obsolete?

Diagnosis, prognosis, treatment, and development of new therapies for diseases or syndromes depend on a reliable means of identifying phenotypes associated with distinct predictive probabilities for these various objectives. Left ventricular ejection fraction (LVEF) provides the current basis for combined functional and structural phenotyping in heart failure by classifying patients as those with heart failure with reduced ejection fraction (HFrEF) and those with heart failure with preserved ejection fraction (HFpEF). Recently the utility of LVEF as the major phenotypic determinant of heart failure has been challenged based on its load dependency and measurement variability. We review the history of the development and adoption of LVEF as a critical measurement of LV function and structure and demonstrate that, in chronic heart failure, load dependency is not an important practical issue, and we provide hemodynamic and molecular biomarker evidence that LVEF is superior or equal to more unwieldy methods of identifying phenotypes of ventricular remodeling. We conclude that, because it reliably measures both left ventricular function and structure, LVEF remains the best current method of assessing pathologic remodeling in heart failure in both individual clinical and multicenter group settings. Because of the present and future importance of left ventricular phenotyping in heart failure, LVEF should be measured by using the most accurate technology and methodologic refinements available, and improved characterization methods should continue to be sought.

A genotype-directed comparative effectiveness trial of Bucindolol and metoprolol succinate for prevention of symptomatic atrial fibrillation/atrial flutter in patients with heart failure: Rationale and design of the GENETIC-AF trial

BACKGROUND

Few therapies are available for the safe and effective treatment of atrial fibrillation (AF) in patients with heart failure. Bucindolol is a non-selective beta-blocker with mild vasodilator activity previously found to have accentuated antiarrhythmic effects and increased efficacy for preventing heart failure events in patients homozygous for the major allele of the ADRB1 Arg389Gly polymorphism (ADRB1 Arg389Arg genotype). The safety and efficacy of bucindolol for the prevention of AF or atrial flutter (AFL) in these patients has not been proven in randomized trials.

METHODS/DESIGN

The Genotype-Directed Comparative Effectiveness Trial of Bucindolol and Metoprolol Succinate for Prevention of Symptomatic Atrial Fibrillation/Atrial Flutter in Patients with Heart Failure (GENETIC-AF) trial is a multicenter, randomized, double-blinded "seamless" phase 2B/3 trial of bucindolol hydrochloride versus metoprolol succinate, for the prevention of symptomatic AF/AFL in patients with reduced ejection fraction heart failure (HFrEF). Patients with pre-existing HFrEF and recent history of symptomatic AF are eligible for enrollment and genotype screening, and if they are ADRB1 Arg389Arg, eligible for randomization. A total of approximately 200 patients will comprise the phase 2B component and if pre-trial assumptions are met, 620 patients will be randomized at approximately 135 sites to form the Phase 3 population. The primary endpoint is the time to recurrence of symptomatic AF/AFL or mortality over a 24-week follow-up period, and the trial will continue until 330 primary endpoints have occurred.

CONCLUSIONS

GENETIC-AF is the first randomized trial of pharmacogenetic guided rhythm control, and will test the safety and efficacy of bucindolol compared with metoprolol succinate for the prevention of recurrent symptomatic AF/AFL in patients with HFrEF and an ADRB1 Arg389Arg genotype. (ClinicalTrials.govNCT01970501).

Filamin C Truncation Mutations Are Associated With Arrhythmogenic Dilated Cardiomyopathy and Changes in the Cell-Cell Adhesion Structures

OBJECTIVES

The purpose of this study was to assess the phenotype of Filamin C (FLNC) truncating variants in dilated cardiomyopathy (DCM) and understand the mechanism leading to an arrhythmogenic phenotype.

BACKGROUND

Mutations in FLNC are known to lead to skeletal myopathies, which may have an associated cardiac component. Recently, the clinical spectrum of FLNC mutations has been recognized to include a cardiac-restricted presentation in the absence of skeletal muscle involvement.

METHODS

A population of 319 U.S. and European DCM cardiomyopathy families was evaluated using whole-exome and targeted next-generation sequencing. FLNC truncation probands were identified and evaluated by clinical examination, histology, transmission electron microscopy, and immunohistochemistry.

RESULTS

A total of 13 individuals in 7 families (2.2%) were found to harbor 6 different FLNC truncation variants (2 stopgain, 1 frameshift, and 3 splicing). Of the 13 FLNC truncation carriers, 11 (85%) had either ventricular arrhythmias or sudden cardiac death, and 5 (38%) presented with evidence of right ventricular dilation. Pathology analysis of 2 explanted hearts from affected FLNC truncation carriers showed interstitial fibrosis in the right ventricle and epicardial fibrofatty infiltration in the left ventricle. Ultrastructural findings included occasional disarray of Z-discs within the sarcomere. Immunohistochemistry showed normal plakoglobin signal at cell-cell junctions, but decreased signals for desmoplakin and synapse-associated protein 97 in the myocardium and buccal mucosa.

CONCLUSIONS

We found FLNC truncating variants, present in 2.2% of DCM families, to be associated with a cardiac-restricted arrhythmogenic DCM phenotype characterized by a high risk of life-threatening ventricular arrhythmias and a pathological cellular phenotype partially overlapping with arrhythmogenic right ventricular cardiomyopathy.

Entrepreneurialism in the Translational Biologic Sciences: Why, How, and However

Because they are perceived as distinct from the biological sciences, entrepreneurial pursuits may be daunting to the average researcher. In this report, we explain why academic scientists and in particular translational researchers should be naturally as well as rationally attracted to entrepreneurial endeavors. We go into some detail of how entrepreneurial achievements are actually accomplished and offer a few caveats for consideration when embarking down entrepreneurial pathways. We conclude that, although not for everyone, for translational investigators in the biologic sciences, entrepreneurial pursuits are desirable, accomplishable, and professionally rewarding.

Histamine H2 Receptor Polymorphisms, Myocardial Transcripts, and Heart Failure (from the Multi-Ethnic Study of Atherosclerosis and Beta-Blocker Effect on Remodeling and Gene Expression Trial)

Myocardial H₂ receptor activation contributes to heart failure (HF) in preclinical models, and H₂ receptor antagonists are associated with decreased HF incidence. This study evaluated whether H₂ histamine receptor (HRH2) single nucleotide polymorphisms (SNPs) are associated with HF incidence and whether myocardial transcript abundance is associated with HF recovery. The association of SNPs in HRH2 with incident HF was characterized using Cox proportional hazards regression among participants in the Multi-Ethnic Study of Atherosclerosis. Differences in myocardial HRH2 transcripts were characterized in participants with dilated cardiomyopathy comparing 6 "super-responders" with 6 nonresponders to β blockade in the Beta-Blocker Effect on Remodeling and Gene Expression Trial. In MESA, no candidate SNP was associated with HF in black, Hispanic, or white participants. The rs2241562 minor allele was present only in Chinese participants and the adjusted HF hazard among those with 1 or more copies of this allele was 3.7, 95% confidence interval 1.0 to 13.4. In BORG, super-responders to β blockade had higher levels of myocardial HRH2 transcript at baseline compared with nonresponders (fragments per kilobase per transcript per million mapped reads: Variant 2, 5.5 ± 1.1 compared with 3.2 ± 0.8 in nonresponders, p = 0.002; Variant 1 + 2, 32.1 ± 7.4 compared with 23.3 ± 4.2 in nonresponders, p = 0.04). In conclusion, the presence of a minor allele at rs2241562 was associated with increased HF incidence in Chinese participants. Differences in myocardial HRH2 transcript abundance were seen in participants with dilated cardiomyopathy who responded to β blockade. These observations support the hypothesis that HRH2 is involved in the pathogenesis of HF.