Effect of chronic beta-adrenergic receptor blockade in congestive cardiomyopathy

From "contraindicated" to "first line" - Current mechanistic insights beyond canonical β-receptor signaling

β-blockers are a solid pillar in the treatment of cardiovascular diseases. However, they are highly discussed regarding effectiveness for certain indications and side-effects. Even though there are up to 20 licensed compounds, only four are used for heart failure (HF) therapy. On the receptor level several key characteristics seem to influence the clinical outcome: subtype selectivity, antagonistic vs (inverse/biased) agonistic properties and -in particular- ancillary capacities. On a molecular level, divergent and novel signaling patterns are being identified and extra-cardiac effects on e.g. inflammation, metabolism and oxidative stress are highlighted. This review discusses different well-known and newly discovered characteristics that need to be considered for HF therapy and in the context of co-morbidities.

Impact of heart rate changes during hospitalization on outcome in heart failure with preserved ejection fraction

AIMS

The benefits of lowering heart rate (HR) in heart failure (HF) with preserved ejection fraction (HFpEF) patients are still a matter of debate. This study aimed to investigate the relationship between changes in HR during hospitalization and cardiovascular (CV) events and all-cause death in hospitalized HFpEF patients.

METHODS AND RESULTS

Hospitalized HF patients between January 2017 and December 2021 were consecutively enrolled in a national, multicentred, and prospective registry database, the China Cardiovascular Association Database-HF Center Registry. HF patients with a left ventricular ejection fraction of ≥50% were defined as HFpEF patients. The study analysed admission/discharge HR, change in HR during hospitalization (∆HR), and ∆HR ratio (∆HR/admission HR). The patients were categorized into three groups: no HR dropping group (ΔHR ratio > 0.0%), moderate HR dropping group (-15% < ΔHR ratio ≤ 0.0%), and excessive HR dropping group (ΔHR ratio ≤ -15%). All patients were followed up for 12 months. The primary endpoint was CV events (CV death or HF rehospitalization). The secondary endpoint was all-cause death. A total of 19 510 HFpEF patients (9750 males, mean age 71.9 ± 12.2 years) were included, with 4575 in the no HR dropping group, 8434 in the moderate HR dropping group, and 6501 in the excessive HR dropping group. Excessive HR dropping during hospitalization was significantly associated with an increased risk of CV events (17.1%) compared with the no HR dropping group (14.5%, P < 0.001) or the moderate HR dropping group (14.0%, P < 0.001), although all-cause mortality was similar among the three groups. After adjusting for multiple confounding factors, excessive HR dropping remained an independent predictor of increased CV event risk [hazard ratio 1.197, 95% confidence interval (CI) 1.078-1.328]. Subgroup analysis revealed that the prognostic impact of excessive HR dropping on increased CV event risk remained in the subgroups of older age, New York Heart Association class IV, ischaemic HF, higher left ventricular ejection fraction, absence of chronic kidney disease, and use of beta-blockers or ivabradine. Independent determinants associated with excessive HR dropping during admission included use of beta-blockers [odds ratio (OR) 1.683, 95% CI 1.558-1.819], lower discharge diastolic blood pressure (OR 0.988, 95% CI 0.985-0.991), no pacemaker (OR 0.501, 95% CI 0.416-0.603), coexisting atrial fibrillation or atrial flutter (OR 1.327, 95% CI 1.218-1.445), and use of digoxin (OR 1.340, 95% CI 1.213-1.480).

CONCLUSIONS

In hospitalized HFpEF patients, excessive HR dropping during hospitalization is associated with an increased risk of CV death or HF rehospitalization. These findings highlight the importance of HR monitoring and avoiding excessively slowing down HR in hospitalized HFpEF patients to reduce the risk of CV events.

Beta-blocker management in patients admitted for acute heart failure and reduced ejection fraction: a review and expert consensus opinion

The role of the beta-adrenergic signaling pathway in heart failure (HF) is pivotal. Early blockade of this pathway with beta-blocker (BB) therapy is recommended as the first-line medication for patients with HF and reduced ejection fraction (HFrEF). Conversely, in patients with severe acute HF (AHF), including those with resolved cardiogenic shock (CS), BB initiation can be hazardous. There are very few data on the management of BB in these situations. The present expert consensus aims to review all published data on the use of BB in patients with severe decompensated AHF, with or without hemodynamic compromise, and proposes an expert-recommended practical algorithm for the prescription and monitoring of BB therapy in critical settings.

The Promises of Proteomics and Metabolomics for Unravelling the Mechanism and Side Effect Landscape of Beta-Adrenoceptor Antagonists in Cardiovascular Therapeutics

Cardiovascular medicine witnessed notable advances for the past decade. Multiomics research offers a new lens for precision/personalized medicine for existing and emerging drugs used in the cardiovascular clinic. Beta-blockers are vital in treating hypertension and chronic heart failure. However, clinical use of beta-blockers is also associated with side effects and person-to-person variations in their pharmacokinetics and pharmacodynamics. A comprehensive understanding of the mechanisms that underpin the side effect landscape of beta-blockers is imperative to optimize their therapeutic value. In addition, current research emphasizes the circadian clock's vital roles in regulating pharmacological parameters. Administration of the beta-blockers at specific dosing times could potentially improve their effectiveness and reduce their toxic effects. The rapid development of mass spectrometry technologies with chemical proteomics and thermal proteome profiling methods has also substantially advanced our understanding of underlying side effects mechanisms by unbiased deconvolution of drug targets and off-targets. Metabolomics is steadily demonstrating its utility for conducting mechanistic and toxicological analyses of pharmacological compounds. This article discusses the promises of cutting-edge proteomics and metabolomics approaches to investigate the molecular targets, mechanism of action, adverse effects, and dosing time dependency of beta-blockers.

Short-term outcomes by chronic betablocker treatment in patients presenting to emergency departments with acute heart failure: BB-EAHFE

AIMS

To evaluate the association between chronic treatment with betablockers (BB) and the severity of decompensation and short-term outcomes of patients with acute heart failure (AHF).

METHODS AND RESULTS

We consecutively included all patients presenting with AHF to 45 Spanish emergency departments (ED) during six different time-periods between 2007 and 2018. Patients were stratified according to whether they were on chronic treatment with BB at the time of ED consultation. Those receiving BB were compared (adjusted odds ratio-OR-with 95% confidence interval-CI-) with those not receiving BB group in terms of in-hospital and 7-day all-cause mortality, need for hospitalization, and prolonged length of stay (≥7 days). Among the 17 923 recruited patients (median age: 80 years; 56% women), 7795 (43%) were on chronic treatment with BB. Based on the MEESSI-AHF risk score, those on BB were at lower risk. In-hospital mortality was observed in 1310 patients (7.4%), 7-day mortality in 765 (4.3%), need for hospitalization in 13 428 (75.0%), and prolonged length of stay (43.3%). After adjustment for confounding, those on chronic BB were at lower risk for in-hospital all-cause mortality (OR = 0.85, 95% CI = 0.79-0.92, P < 0.001); 7-day all-cause mortality (OR = 0.77, 95% CI = 0.70-0.85, P < 0.001); need for hospitalization (OR = 0.89, 95% CI = 0.85-0.94, P < 0.001); prolonged length of stay (OR = 0.90, 95% CI = 0.86-0.94, P < 0.001). A propensity matching approach yielded consistent findings.

CONCLUSION

In patients presenting to ED with AHF, those on BB had better short-term outcomes than those not receiving BB.

Subcellular β-Adrenergic Receptor Signaling in Cardiac Physiology and Disease

ABSTRACT

Adrenergic receptors are critical regulators of cardiac function with profound effects on cardiac output during sympathetic stimulation. Chronic stimulation of the adrenergic system of the heart under conditions of cardiac stress leads to cardiac dysfunction, hypertrophy, and ultimately failure. Emerging data have revealed that G protein-coupled receptors in intracellular compartments are functionally active and regulate distinct cellular processes from those at the cell surface. β2 adrenergic receptors internalize onto endosomes in various cell types where they have recently been shown to continue to stimulate cAMP production to selectively regulate gene expression. Other studies have identified β1 adrenergic receptors at the nuclear envelope and the Golgi apparatus. Here, we discuss data on signaling by β1 and β2 adrenergic receptors in the heart and the possible influence of their subcellular locations on their divergent physiological functions in cardiac myocytes and in cardiac pathology. Understanding the relative roles of these receptors at these locations could have a significant impact on pharmacological targeting of these receptors for the treatment of heart failure and cardiac diseases.

Ecklonia stolonifera Okamura Extract Suppresses Myocardial Infarction-Induced Left Ventricular Systolic Dysfunction by Inhibiting p300-HAT Activity

Ecklonia stolonifera Okamura extract (ESE) has been reported to have various bioactive effects, but its effects on cardiovascular disease have not yet been investigated. First, primary neonatal rat cultured cardiomyocytes were treated with ESE and stimulated with phenylephrine (PE) for 48 h. ESE (1000 µg/mL) significantly suppressed PE-induced cardiomyocyte hypertrophy, hypertrophy-related gene transcription, and the acetylation of histone H3K9. An in vitro p300-HAT assay indicated that ESE directly inhibited p300-HAT activity. Next, one week after myocardial infarction (MI) surgery, rats (left ventricular fractional shortening (LVFS) < 40%) were randomly assigned to three groups: vehicle (saline, n = 9), ESE (0.3 g/kg, n = 10), or ESE (1 g/kg, n = 10). Daily oral administration was carried out for 8 weeks. After treatment, LVFS was significantly higher in the ESE (1 g/kg) group than in the vehicle group. The ESE treatments also significantly suppressed MI-induced increases in myocardial cell diameter, perivascular fibrosis, hypertrophy- and fibrosis-related gene transcription, and the acetylation of histone H3K9. These results suggest that ESE suppressed both hypertrophic responses in cardiomyocytes and the development of heart failure in rats by inhibiting p300-HAT activity. Thus, this dietary extract is a potential novel therapeutic strategy for heart failure in humans.

Medical Management of Patients With Heart Failure and Reduced Ejection Fraction

The options for treating heart failure with reduced ejection fraction (HFrEF) have expanded considerably over the past decade. While neurohormonal modulation using angiotensin converting enzyme inhibitors and angiotensin receptor blockers, beta blockers and mineralocorticoid receptor antagonists remain the cornerstone of therapy, additional novel approaches including angiotensin receptor neprilysin inhibitors, sodium glucose cotransporter 2 inhibitors, ivrabradine, vericiguat and omecamtiv mecarbil have been shown to improve outcomes in patients with HFrEF. This reviews summarizes currently available approaches as well as promising additional strategies that may be used in the future.

Treatment options for patients with heart failure (HF) with reduced ejection fraction (HFrEF) have expanded considerably over the past few decades. Whereas neurohormonal modulation remains central to the management of patients with HFrEF, other pathways have been targeted with drugs that have novel mechanisms of action. The angiotensin receptor-neprilysin inhibitors (ARNIs) which enhance levels of compensatory molecules such as the natriuretic peptides while simultaneously providing angiotensin receptor blockade have emerged as the preferred strategy for inhibiting the renin angiotensin system. Sodium glucose cotransporter 2 (SGLT2) inhibitors which were developed as hypoglycemic agents have been shown to improve outcomes in patients with HF regardless of their diabetic status. These agents along with beta blockers and mineralocorticoid receptor antagonists are the core medical therapies for patients with HFrEF. Additional approaches using ivabradine to slow heart rate in patients with sinus rhythm, the hydralazine/isosorbide dinitrate combination to unload the heart, digoxin to provide inotropic support and vericiguat to augment cyclic guanosine monophosphate production have been shown in well-designed trials to have beneficial effects in the HFrEF population and are used as adjuncts to the core therapies in selected patients. This review provides an overview of the medical management of patients with HFrEF with focus on the major developments that have taken place in the field. It offers prospective of how these drugs should be employed in clinical practice and also a glimpse into some strategies that may prove to be useful in the future.

Sympatho-adrenergic mechanisms in heart failure: new insights into pathophysiology

The sympathetic nervous system is activated in the setting of heart failure (HF) to compensate for hemodynamic instability. However, acute sympathetic surge or sustained high neuronal firing rates activates β-adrenergic receptor (βAR) signaling contributing to myocardial remodeling, dysfunction and electrical instability. Thus, sympatho-βAR activation is regarded as a hallmark of HF and forms pathophysiological basis for β-blocking therapy. Building upon earlier research findings, studies conducted in the recent decades have significantly advanced our understanding on the sympatho-adrenergic mechanism in HF, which forms the focus of this article. This review notes recent research progress regarding the roles of cardiac β2AR or α1AR in the failing heart, significance of β1AR-autoantibodies, and βAR signaling through G-protein independent signaling pathways. Sympatho-βAR regulation of immune cells or fibroblasts is specifically discussed. On the neuronal aspects, knowledge is assembled on the remodeling of sympathetic nerves of the failing heart, regulation by presynaptic α2AR of NE release, and findings on device-based neuromodulation of the sympathetic nervous system. The review ends with highlighting areas where significant knowledge gaps exist but hold promise for new breakthroughs.

Contemporary Pillars of Heart Failure with Reduced Ejection Fraction Medical Therapy

Heart failure with reduced ejection fraction (HFrEF) is a clinical condition associated with cardiac contractility impairment. HFrEF is a significant public health issue with a high morbidity and mortality burden. Pathological left ventricular (LV) remodeling and progressive dilatation are hallmarks of HFrEF pathogenesis, ultimately leading to adverse clinical outcomes. Therefore, cardiac remodeling attenuation has become a treatment goal and a standard of care over the last three decades. Guideline-directed medical therapy mainly targeting the sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS) has led to improved survival and a reduction in HF hospitalization in this population. More recently, novel pharmacological therapies targeting other pathways implicated in the pathophysiology of HFrEF have emerged at an exciting rate, with landmark clinical trials demonstrating additive clinical benefits in patients with HFrEF. Among these novel therapies, angiotensin receptor-neprilysin inhibitors (ARNI), sodium-glucose cotransporter-2 inhibitors (SGLT2i), vericiguat (a novel oral guanylate cyclase stimulator), and omecamtiv mecarbil (a selective cardiac myosin activator) have shown improved clinical benefit when added to the traditional standard-of-care medical therapy in HFrEF. These new comprehensive data have led to a remarkable change in the medical therapy paradigm in the setting of HFrEF. This article will review the pivotal studies involving these novel agents and present a suggestive paradigm of pharmacological therapy representing the 2021 European Society of Cardiology (ESC) guidelines for the treatment of chronic HFrEF.

Efficacy of Add-on Therapy with Carvedilol and the Direct Renin Inhibitor Aliskiren for Improving Cardiac Sympathetic Nerve Activity, Cardiac Function, Symptoms, Exercise Capacity and Brain Natriuretic Peptide in Patients with Dilated Cardiomyopathy

Purpose/Method: Aliskiren is a direct renin inhibitor that has been reported to be effective for CHF, but the usefulness of combined therapy with carvedilol and aliskiren has not been reported. Forty-four patients with dilated cardiomyopathy (DCM) were randomized into a group receiving add-on therapy with carvedilol plus aliskiren and another group receiving carvedilol alone for 6 months. Nuclear imagings with ¹²³I-Metaiodobenzylguanidine (MIBG) and ^99mTc-Sestamibi were performed. Exercise capacity using a specific activity scale (SAS) and the New York Heart Association (NYHA) class were evaluated. Cardiac sympathetic nerve activity was evaluated by ¹²³I-MIBG imaging, with the delayed heart-to-mediastinum activity ratio (H/M), delayed total defect score (TDS), and washout rate (WR). Results: Combined add-on therapy with carvedilol and aliskiren improved several parameters much more than carvedilol alone (p<0.05) with respect to TDS, ejection fraction (EF), NYHA, SAS on 6 months and the changes in TDS, EF, end-diastolic volume and brain natriuretic peptide (BNP). Conclusion: Add-on therapy with carvedilol and aliskiren is more effective than carvedilol alone for improving cardiac sympathetic nerve activity, cardiac function, symptoms, exercise capacity, and brain natriuretic peptide in patients with DCM.

Mitochondria-Rich Extracellular Vesicles From Autologous Stem Cell-Derived Cardiomyocytes Restore Energetics of Ischemic Myocardium

BACKGROUND

Mitochondrial dysfunction results in an imbalance between energy supply and demand in a failing heart. An innovative therapy that targets the intracellular bioenergetics directly through mitochondria transfer may be necessary.

OBJECTIVES

The purpose of this study was to establish a preclinical proof-of-concept that extracellular vesicle (EV)-mediated transfer of autologous mitochondria and their related energy source enhance cardiac function through restoration of myocardial bioenergetics.

METHODS

Human-induced pluripotent stem cell-derived cardiomyocytes (iCMs) were employed. iCM-conditioned medium was ultracentrifuged to collect mitochondria-rich EVs (M-EVs). Therapeutic effects of M-EVs were investigated using in vivo murine myocardial infarction (MI) model.

RESULTS

Electron microscopy revealed healthy-shaped mitochondria inside M-EVs. Confocal microscopy showed that M-EV-derived mitochondria were transferred into the recipient iCMs and fused with their endogenous mitochondrial networks. Treatment with 1.0 × 10⁸/ml M-EVs significantly restored the intracellular adenosine triphosphate production and improved contractile profiles of hypoxia-injured iCMs as early as 3 h after treatment. In contrast, isolated mitochondria that contained 300× more mitochondrial proteins than 1.0 × 10⁸/ml M-EVs showed no effect after 24 h. M-EVs contained mitochondrial biogenesis-related messenger ribonucleic acids, including proliferator-activated receptor γ coactivator-1α, which on transfer activated mitochondrial biogenesis in the recipient iCMs at 24 h after treatment. Finally, intramyocardial injection of 1.0 × 10⁸ M-EVs demonstrated significantly improved post-MI cardiac function through restoration of bioenergetics and mitochondrial biogenesis.

CONCLUSIONS

M-EVs facilitated immediate transfer of their mitochondrial and nonmitochondrial cargos, contributing to improved intracellular energetics in vitro. Intramyocardial injection of M-EVs enhanced post-MI cardiac function in vivo. This therapy can be developed as a novel, precision therapeutic for mitochondria-related diseases including heart failure.

A Modern History RAAS Inhibition and Beta Blockade for Heart Failure to Underscore the Non-equivalency of ACEIs and ARBs

Beta blockers and renin-angiotensin-aldosterone-inhibitors (RAAS-i) including angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) have been a mainstay of guideline-based medical therapy for heart failure with reduced ejection fraction (HFrEF) for decades. However, initial evidence supporting each of the aforenoted class of drug for heart failure indications was largely found independently of the other two classes with the exception of the addition of BBs to ACEIs. In the initial ACEI trials for HFrEF, few participants were on BBs as BBs were seen as contraindicated in HFrEF at the time. The seminal BB in HFrEF trials had high prevalence of ACEIs use as ACEIs for HF were standard of care by then, but ARBs as a class were still in their infancy. We closely examine the evidence for combinations of BB and ACEIs versus ARBs in HFrEF. In doing so, we demonstrate the lack of evidence for consideration of ARBs to be interchangeable with ACEIs when used in combination with BB and provide evidence that calls in to question the validity of assuming benefits from each drug class are independently cumulative, widening the gap between ACEIs and ARBs when used with BBs. Modern guidelines should emphasize this lack of evidence for the combination use of ARB and BB in HFrEF, except for candesartan. Even as practice moves towards the widespread uptake of angiotensin receptor-neprilysin inhibitors (which contain the ARB valsartan) in heart failure, the distinction has important implications for the ongoing role of combination therapy with BB, which thus far has been assumed, but not proven.

Carvedilol Alters Circulating MiR-1 and MiR-214 in Heart Failure

Introduction

MicroRNAs (miRNAs) are recognized as major contributors in various cardiovascular diseases, such as heart failure (HF). These small noncoding RNAs that posttranscriptionally control target genes are involved in regulating different pathophysiological processes including cardiac proliferation, ifferentiation, hypertrophy, and fibrosis. Although carvedilol, a β-adrenergic blocker, and a drug of choice in HF produce cytoprotective actions against cardiomyocyte hypertrophy, the mechanisms are poorly understood. Here we proposed that the expression of hypertrophic-specific miRNAs (miR-1, miR-133, miR-208, and miR-214) might be linked to beneficial effects of carvedilol.

Methods

The levels of four hypertrophic-specific miRNAs were measured in the sera of 35 patients with systolic HF receiving carvedilol (treated) and 20 HF patients not receiving any β-blockers (untreated) as well as 17 nonHF individuals (healthy) using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Systolic HF was defined as left ventricular ejection fraction <50% by transthoracic echocardiography.

Results

We demonstrated that miR-1 and miR-214 were significantly upregulated in the treated group compared to the untreated group (P=0.014 and 5.3-fold, 0.033 and 4.2-fold, respectively). However, miR-133 and miR-208 did not show significant difference in expression between these two study groups. MiR-1 was significantly downregulated in the untreated group compared with healthy individuals (P=0.019 and 0.14-fold).

Conclusion

In conclusion, it might be postulated that one of the mechanisms by which carvedilol may exert its cardioprotective effects can be through increasing miR-1 and miR-214 expressions which may also serve as a potential therapeutic target in patients with systolic HF in future.

Manipulation of beta-adrenergic receptor in pressure-overloaded murine hearts mimics adverse and reverse cardiac remodeling

Transverse aortic constriction (TAC) has been widely used to create pressure overload induced heart failure in mice. However, this conventional model has some limitations such as low reproducibility and long creation period of cardiac failure. In order to establish a highly reproducible cardiac failure model that mimics adverse cardiac remodeling (ACR) we combined pressure overload and beta-adrenergic receptor stimuli using isoproterenol (ISO) and explored the optimal TAC model by changing the durations of TAC and the doses of ISO. Thus we constructed a suitable model for ACR with an effective combination of 3-week TAC and subsequent one-week ISO (3 mg/kg/day) infusion. Using RNA-Seq analyses, we identified that the up-regulated genes were mainly related to fibrosis including Fbn1, C1qtnf6 and Loxl2; and that the down-regulated genes were associated with mitochondrial function including Uqcrc1, Ndufs3, and Idh2 in failing hearts of our ACR model. Next, we followed the changes in cardiac function after ceasing ISO infusion. Left ventricular function gradually recovered after cessation of ISO, suggesting cardiac reverse remodeling (CRR). Gene expression signatures of hearts, which exhibited CRR, were almost identical to that of TAC hearts without ISO. In conclusion, our new model exhibits a transition to ACR and subsequent CRR with high reproducibility. This murine model might add new insights into the experiments of heart failure technically as well as scientifically.

Heart failure as a substrate and trigger for ventricular tachycardia

Heart failure (HF) is a major cause of morbidity and mortality with more than 5.1 million individuals affected in the USA. Ventricular tachyarrhythmias (VAs) including ventricular tachycardia and ventricular fibrillation are common in patients with heart failure. The pathophysiology of these mechanisms as well as the contribution of heart failure to the genesis of these arrhythmias is complex and multifaceted. Myocardial hypertrophy and stretch with increased preload and afterload lead to shortening of the action potential at early repolarization and lengthening of the action potential at final repolarization which can result in re-entrant ventricular tachycardia. Myocardial fibrosis and scar can create the substrate for re-entrant ventricular tachycardia. Altered calcium handling in the failing heart can lead to the development of proarrhythmic early and delayed after depolarizations. Various medications used in the treatment of HF such as loop diuretics and angiotensin converting enzyme inhibitors have not demonstrated a reduction in sudden cardiac death (SCD); however, beta-blockers (BB) are effective in reducing mortality and SCD. Amongst patients who have HF with reduced ejection fraction, the angiotensin receptor-neprilysin inhibitor (sacubitril/valsartan) has been shown to reduce cardiovascular mortality, specifically by reducing SCD, as well as death due to worsening HF. Implantable cardioverter-defibrillator (ICD) implantation in HF patients reduces the risk of SCD; however, subsequent mortality is increased in those who receive ICD shocks. Prophylactic ICD implantation reduces death from arrhythmia but does not reduce overall mortality during the acute post-myocardial infarction (MI) period (less than 40 days), for those with reduced ejection fraction and impaired autonomic dysfunction. Furthermore, although death from arrhythmias is reduced, this is offset by an increase in the mortality from non-arrhythmic causes. This article provides a review of the aforementioned mechanisms of arrhythmogenesis in heart failure; the role and impact of HF therapy such as cardiac resynchronization therapy (CRT), including the role, if any, of CRT-P and CRT-D in preventing VAs; the utility of both non-invasive parameters as well as multiple implant-based parameters for telemonitoring in HF; and the effect of left ventricular assist device implantation on VAs.

Leveraging Signaling Pathways to Treat Heart Failure With Reduced Ejection Fraction

Advances in the treatment of heart failure with reduced ejection fraction due to systolic dysfunction are engaging an ever-expanding compendium of molecular signaling targets. Well established approaches modifying hemodynamics and cell biology by neurohumoral receptor blockade are evolving, exploring the role and impact of modulating intracellular signaling pathways with more direct myocardial effects. Even well-tread avenues are being reconsidered with new insights into the signaling engaged and thus opportunity to treat underlying myocardial disease. This review explores therapies that have proven successful, those that have not, those that are moving into the clinic but whose utility remains to be confirmed, and those that remain in the experimental realm. The emphasis is on signaling pathways that are tractable for therapeutic manipulation. Of the approaches yet to be tested in humans, we chose those with a well-established experimental history, where clinical translation may be around the corner. The breadth of opportunities bodes well for the next generation of heart failure therapeutics.

Clinical efficacy of carvedilol treatment for dilated cardiomyopathy: A meta-analysis of randomized controlled trials

BACKGROUND

Clinical trials examining the therapeutic benefit of carvedilol on patients with dilated cardiomyopathy have reported inconsistent results. The aim of this study was to evaluate the clinical efficacy of carvedilol on patients with dilated cardiomyopathy.

METHODS

PubMed, Embase, Cochrane Library, web of science, China National Knowledge Infrastructure (CNKI), Wanfang, and Chinese Scientific and Technological Journal (VIP) databases were searched for randomized controlled trials (RCTs) before March 2018. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to evaluate the effects of carvedilol on patients with dilated cardiomyopathy.

RESULTS

Twenty one studies including 1146 participants were included. There were significant improvements on heart rate (HR) (WMD = -14.18, 95% CI: -17.72 to -10.63, P < .001), LVEF (WMD = 7.28, 95% CI: 6.53-8.03, P < .001), SBP (WMD = -10.74, 95% CI: -12.78 to -8.70, P < .001), DBP (WMD = -4.61, 95% CI: -7.32 to -1.90, P = .001), LVEDD (WMD = -2.76, 95% CI: -4.89 to -0.62, P = .011), LVESD (WMD = -3.63, 95% CI: -6.55 to -0.71, P = .015), LVEDV (WMD = -9.30, 95% CI: -11.89 to -6.71, P < .001), LVESV (WMD = -12.28, 95% CI: -14.86 to -9.70, P < .001) under carvedilol treatment compared with control.

CONCLUSION

This meta-analysis demonstrates that carvedilol significantly improves cardiac function on patients with dilated cardiomyopathy. Further large scale, high-quality and multicenter RCTs are still required to confirm the impacts of carvedilol on patients with dilated cardiomyopathy.

Cardio-Immunology of Myocarditis: Focus on Immune Mechanisms and Treatment Options

Myocarditis and inflammatory cardiomyopathy are syndromes, not aetiological disease entities. From animal models of cardiac inflammation we have detailed insight of the strain specific immune reactions based on the genetic background of the animal and the infectiosity of the virus. Innate and adaptive immunity also react in man. An aetiological diagnosis of a viral vs. a non-viral cause is possible by endomyocardial biopsy with histology, immunohistology and PCR for microbial agents. This review deals with the different etiologies of myocarditis and inflammatory cardiomyopathy on the basis of the genetic background and the predisposition for inflammation. It analyses the epidemiologic shift in cardiotropic viral agents in the last 30 years. Based on the understanding of the interaction between infection and the players of the innate and adaptive immune system it summarizes pathogenetic phases and clinical faces of myocarditis. It gives an up-to-date information on specific treatment options beyond symptomatic heart failure and antiarrhythmic therapy. Although inflammation can resolve spontaneously, specific treatment directed to the causative etiology is often required. For fulminant, acute, and chronic autoreactive myocarditis without viral persistence immunosuppressive treatment can be life-saving, for viral inflammatory cardiomyopathy ivIg treatment can resolve inflammation and often eradicate the virus.

Pharmacological heart rate lowering in patients with a preserved ejection fraction-review of a failing concept

Epidemiological studies have demonstrated that high resting heart rates are associated with increased mortality. Clinical studies in patients with heart failure and reduced ejection fraction have shown that heart rate lowering with beta-blockers and ivabradine improves survival. It is therefore often assumed that heart rate lowering is beneficial in other patients as well. Here, we critically appraise the effects of pharmacological heart rate lowering in patients with both normal and reduced ejection fraction with an emphasis on the effects of pharmacological heart rate lowering in hypertension and heart failure. Emerging evidence from recent clinical trials and meta-analyses suggest that pharmacological heart rate lowering is not beneficial in patients with a normal or preserved ejection fraction. This has just begun to be reflected in some but not all guideline recommendations. The detrimental effects of pharmacological heart rate lowering are due to an increase in central blood pressures, higher left ventricular systolic and diastolic pressures, and increased ventricular wall stress. Therefore, we propose that heart rate lowering per se reproduces the hemodynamic effects of diastolic dysfunction and imposes an increased arterial load on the left ventricle, which combine to increase the risk of heart failure and atrial fibrillation. Pharmacologic heart rate lowering is clearly beneficial in patients with a dilated cardiomyopathy but not in patients with normal chamber dimensions and normal systolic function. These conflicting effects can be explained based on a model that considers the hemodynamic and ventricular structural effects of heart rate changes.

Longitudinal evaluation of ventricular ejection fraction and NT-proBNP across heart failure subgroups

OBJECTIVES

Left ventricular ejection fraction (EF) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are important surrogate markers of cardiac function and wall stress. Randomized trials of heart failure (HF) have shown improvements in survival in patients with reduced EF (<40%, HFrEF) but not with preserved EF (≥50%, HFpEF) or mid-range EF (40-49%, HFmrEF). Limited information is available on the trajectory of EF in contemporary heart failure management programs (HFMPs).

DESIGN

201 HF patients consecutively enrolled 2010-2011 in the outpatient-based HFMP of Skåne University Hospital in Lund were included in the study. Probable etiology, EF, NT-proBNP and medications were assessed at baseline and 1 year after enrollment.

RESULTS

HFrEF was the most common heart failure subgroup (78.1% of patients) in this HFMP, followed by HFmrEF (14.9%) and HFpEF (7.0%). The most common etiology was ischemic heart disease (IHD, 40.8%). Complete recovery of EF (>50%) was rare (14.1% of patients with HFrEF and 26.7% with HFmrEF), some degree of improvement was observed in 57.7% and 46.7% of patients. LVEF improved on average 9.1% in patients with HFrEF (p < .001) and NT-proBNP decreased from 4,202 to 2,030 pg/ml (p < .001). A similar trend was noticed for the HFmrEF group but was not statistically significant. The improvement in LVEF was consistent across subgroups with HF attributable to IHD (6.2%), idiopathic dilated cardiomyopathy (7.1%) and tachycardia-induced HF (17.5%).

CONCLUSIONS

This study provides estimates of the improvement in LVEF and NT-proBNP that can be expected with contemporary management across subgroups of HF and different etiologies in a contemporary HFMP.

Influence of Renal Sympathetic Denervation in Patients with Early-Stage Heart Failure Versus Late-Stage Heart Failure

Renal sympathetic denervation (RDN) is currently being investigated in multiple studies of heart failure (HF). Our aim was to assess the safety and effectiveness of RDN in patients with HF, and determine which patients could achieve more beneficial effects of RDN. A total of 17 consecutive patients with HF were enrolled in the study. Clinical symptoms, office blood pressure, and laboratory results were obtained and echocardiography was performed before and 12 months after RDN. Changes from baseline to 12 months were analyzed for all patients and for two subgroups based on HF duration (group 1: HF duration ≤ 3 years, n = 9; group 2: HF duration > 3 years, n = 8). The RDN procedure was successful in all patients and no procedure-related complications were documented. In comparison to baseline, there was a significant increase in left ventricular ejection fraction (LVEF) in all patients and group 1 (P < 0.05 for both), which did not happen in group 2. LAD, LVDs, and RVD also showed a significant reduction in group 1 (P < 0.05 for both). At 12 months, the reductions in TNF-α and CRP were significant for all patients and for patients in group 1 separately. No obvious changes in echocardiographic parameters, 6-minute walking distance, TNF-α, or CRP were recorded in group 2. No changes in BNP in either group were observed at the 12th month of follow-up. RDN could improve cardiac function and led to a significant drop in inflammatory markers in patients with HF. We also found that patients in early-stage HF could benefit more from RDN.

Heart Failure and Sudden Cardiac Death

The Centers for Diseases Control and Prevention estimates that 5.7 million adults in the United States suffer from heart failure and 1 in 9 deaths in 2009 cited heart failure as a contributing cause. Almost 50% of patients who are diagnosed with heart failure die within 5 years of diagnosis. Cardiovascular disease is a public health burden. The prognosis of patients with heart failure has improved significantly. However, the risk for death remains high. Managing sudden death risk and intervening appropriately with primary or secondary prevention strategies are of paramount importance.

Heart Failure: A Class Review of Pharmacotherapy

A recent guideline update for the treatment of heart failure has created the need for a new look at the medication classes and trials related to the disease. The authors focus on pharmacological options available for treating the problem.

Analysis of Clinical Efficacy and Adverse Effects of β-Blocking Agents Used Clinically for Chronic Heart Failure

Clinical efficacy and adverse effects of the β-blocking agents, carvedilol, bisoprolol, and metoprolol were analyzed theoretically, and then compared quantitatively, for the purpose of determining their proper use for chronic heart failure. Initially, we evaluated occupancy binding to the β₁ and β₂ receptors (Фss^β₁ and Фss^β₂) by these drugs. Thereafter, we examined the relationship between Фss^β₁ values and left ventricular ejection fraction (LVEF) increase rate to determine efficacy. The result showed that the efficacy with carvedilol could be attained with a lower Фss^β₁ value than the others. Therefore, we constructed a model under the assumption that β-blocking agents exert both indirect action of LVEF increase through the β₁ receptor and direct action on ryanodine receptor 2. Using the model, it was suggested that these drugs have no differences in regard to the efficacy, while it was clarified theoretically that only carvedilol produces an effect that directly involves ryanodine receptor 2 at clinical doses. We also investigated decreases in heart rate and forced expiratory volume in 1 s as adverse effects of β-blocking agents using a ternary complex model. It was indicated that carvedilol is less likely to induce a heart rate decrease. Meanwhile, it was also suggested that the risk of an asthmatic attack was higher for carvedilol at clinical doses. Our results are considered useful for selection of a proper β-blocking agent and its administration at a reasonable dose for successful heart failure therapy.

Effects of Long-Acting Loop Diuretics in Heart Failure With Reduced Ejection Fraction Patients With Cardiac Resynchronization Therapy

There have been no reports evaluating the impact of long-acting loop diuretics (LLD) on the outcome of heart failure (HF) and arrhythmia treatment in HF with reduced ejection fraction (HFrEF) patients implanted with a cardiac resynchronization therapy (CRT) device.This was a prospective, single-blind, randomized crossover study. We allocated 21 consecutive CRT implanted patients into 2 groups. The furosemide group received furosemide as a first treatment and azosemide as a second treatment. The azosemide group received this treatment in the reverse order. The first treatment was given to each group for 6 months and the second treatment continued for an additional 6 months. We combined the data of each medication regimen in each group and analyzed it at baseline, 6 months, and 1 year. The primary endpoints were the variation of fluid index and thoracic impedance measured by CRT at 6 months.The baseline characteristics were similar for both groups. The difference in the primary endpoints was not statistically significant between the 2 medication arms (fluid index: -29.6 ± 64.4 versus 16.2 ± 48.2; P = 0.22, thoracic impedance: -0.49 ± 17.8 versus 2.45 ± 12.5; P = 0.56). Likewise, the clinical outcome of HF and the CRT derived parameters in both arms were comparable.HFrEF patients taking LLD after CRT implantation might be comparable to those taking short-acting loop diuretics in the treatment of HF and HF-associated arrhythmias.

Comparative Efficacy of Nebivolol and Metoprolol to Prevent Tachycardia-Induced Cardiomyopathy in a Porcine Model

Chronic tachycardia is a well-known cause of nonischemic cardiomyopathy. We hypothesized that nebivolol, a β-blocker with nitric oxide activity, would be superior to a pure β-blocker in preventing tachycardia-induced cardiomyopathy in a porcine model. Fifteen healthy Yucatan pigs were randomly assigned to receive nebivolol, metoprolol, or placebo once a day. All pigs underwent dual-chamber pacemaker implantation. The medication was started the day after the pacemaker implantation. On day 7 after implantation, each pacemaker was set at atrioventricular pace (rate, 170 beats/min), and the pigs were observed for another 7 weeks. Transthoracic echocardiograms, serum catecholamine levels, and blood chemistry data were obtained at baseline and at the end of the study. At the end of week 8, the pigs were euthanized, and complete histopathologic studies were performed. All the pigs developed left ventricular cardiomyopathy but remained hemodynamically stable and survived to the end of the study. The mean left ventricular ejection fraction decreased from baseline by 34%, 20%, and 20% in the nebivolol, metoprolol, and placebo groups, respectively. These changes did not differ significantly among the 3 groups (P =0.51). Histopathologic analysis revealed mild left ventricular perivascular fibrosis with cardiomyocyte hypertrophy in 14 of the 15 pigs. Both nebivolol and metoprolol failed to prevent cardiomyopathy in our animal model of persistent tachycardia and a high catecholamine state.

ACT-ONE - ACTION at last on cancer cachexia by adapting a novel action beta-blocker

Novel action beta-blockers combine many different pharmacological effects. The espindolol exhibits effects through β and central 5-HT1α receptors to demonstrate pro-anabolic, anti-catabolic, and appetite-stimulating actions. In the ACT-ONE trial, espindolol reversed weight loss and improved handgrip strength in patients with cachexia due to non-small cell lung cancer or colorectal cancer. With this trial, another frontier of cachexia management is in sight. Nonetheless, more efficacy and safety data is needed before new therapeutic indications for novel action beta-blockers can be endorsed.

Autonomic Modulation in Heart Failure: Ready for Prime Time?

It has been known for many decades that multiple abnormalities of the autonomic nervous system (ANS) are present in heart failure (HF). Moreover, many of the effective therapies currently used to treat HF have either direct or indirect effects on the ANS. While therapies that block over-activity of the sympathetic nervous system are now standard of care, much less well studied are therapies aimed at augmenting the parasympathetic nervous system. This review will cover recent and ongoing investigations targeting modulation of the ANS, especially highlighting new and ongoing studies directed toward augmenting parasympathetic mechanisms.

Transcriptomic Analysis Identifies the Effect of Beta-Blocking Agents on a Molecular Pathway of Contraction in the Heart and Predicts Response to Therapy

Over the last decades, beta-blockers have been a key component of heart failure therapy. However, currently there is no method to identify patients who will benefit from beta-blocking therapy versus those who will be unresponsive or worsen. Furthermore, there is an unmet need to better understand molecular mechanisms through which heart failure therapies, such as beta-blockers, improve cardiac function, in order to design novel targeted therapies. Solving these issues is an important step towards personalized medicine. Here, we present a comprehensive transcriptomic analysis of molecular pathways that are affected by beta-blocking agents and a transcriptomic biomarker to predict therapy response.

β-adrenergic receptor signalling and its functional consequences in the diseased heart

BACKGROUND

To maintain the balance between the demand of the body and supply (cardiac output), cardiac performance is tightly regulated via the parasympathetic and sympathetic nervous systems. In heart failure, cardiac output (supply) is decreased due to pathologic remodelling of the heart. To meet the demands of the body, the sympathetic system is activated and catecholamines stimulate β-adrenergic receptors (β-ARs) to increase contractile performance and cardiac output. Although this is beneficial in the acute phase, chronic β-ARs stimulation initiates a cascade of alterations at the cellular level, resulting in a diminished contractile performance of the heart.

MATERIALS AND METHODS

This narrative review includes results from previously published systematic reviews and clinical and basic research publications obtained via PubMed up to May 2015.

RESULTS

We discuss the alterations that occur during sustained β-AR stimulation in diseased myocardium and emphasize the consequences of β-AR overstimulation for cardiac function. In addition, current treatment options as well as future therapeutic strategies to treat patients with heart failure to normalize consequences of β-AR overstimulation are discussed.

CONCLUSIONS

The heart is able to protect itself from chronic stimulation of the β-ARs via desensitization and reduced membrane availability of the β-ARs. However, ultimately this leads to an impaired downstream signalling and decreased protein kinase A (PKA)-mediated protein phosphorylation. β-blockers are widely used to prevent β-AR overstimulation and restore β-ARs in the failing hearts. However, novel and more specific therapeutic treatments are needed to improve treatment of HF in the future.

Clinical Characteristics and Treatment of Cardiomyopathies in Children

Cardiomyopathies are diseases of the heart muscle, a term introduced in 1957 to identify a group of myocardial diseases not attributable to coronary artery disease. The definition has since been modified to refer to structural and or functional abnormalities of the myocardium where other known causes of myocardial dysfunction, such as systemic hypertension, valvular disease and ischemic heart disease, have been excluded. In this review, we discuss the pathophysiology, clinical assessment and therapeutic strategies for hypertrophic, dilated and hypertrophic cardiomyopathies, with a particular focus on aspects unique to children.

The safety and tolerability of beta blockers in heart failure with reduced ejection fraction: is the current underutilization of this evidence-based therapy justified?

INTRODUCTION

Beta blockers are one of the cornerstones for treatment of Heart Failure with Reduced Ejection fraction (HFRef), yet their use is often limited by adverse effects, either perceived or real. We performed a review of available data using PubMed.gov utilizing beta blocker, heart failure, reduced ejection fraction and safety as key words.

AREAS COVERED

Several well designed, large scale randomized clinical trials including CIBS-II (bisoprolol), MERIT-HF (metoprolol succinate), and Copernicus (carvedilol) among others, have been conducted in patients with HFRef and demonstrated an improvement in cardiac mortality and morbidity. Despite the preponderance of data supporting the use of beta blockers for patients HFRef, these medications remain underutilized and/or are often prescribed at lower than recommended dosages. Some of the reluctance to embrace beta blockade may be attributed to concern on the part of both the patient and prescriber about the non-cardiac adverse effects of this class of drugs. We have reviewed several recent reviews and meta-analyses of trials of beta blocker in heart failure which have conclusively demonstrated their tolerability in the populations studied.

EXPERT OPINION

In the final section of this paper we provide our opinions regarding initiating and optimizing beta blocker therapy for patients with HFRef.

Myocardial MiR-30 downregulation triggered by doxorubicin drives alterations in β-adrenergic signaling and enhances apoptosis

The use of anthracyclines such as doxorubicin (DOX) has improved outcome in cancer patients, yet associated risks of cardiomyopathy have limited their clinical application. DOX-associated cardiotoxicity is frequently irreversible and typically progresses to heart failure (HF) but our understanding of molecular mechanisms underlying this and essential for development of cardioprotective strategies remains largely obscure. As microRNAs (miRNAs) have been shown to play potent regulatory roles in both cardiovascular disease and cancer, we investigated miRNA changes in DOX-induced HF and the alteration of cellular processes downstream. Myocardial miRNA profiling was performed after DOX-induced injury, either via acute application to isolated cardiomyocytes or via chronic exposure in vivo, and compared with miRNA profiles from remodeled hearts following myocardial infarction. The miR-30 family was downregulated in all three models. We describe here that miR-30 act regulating the β-adrenergic pathway, where preferential β1- and β2-adrenoceptor (β1AR and β2AR) direct inhibition is combined with Giα-2 targeting for fine-tuning. Importantly, we show that miR-30 also target the pro-apoptotic gene BNIP3L/NIX. In aggregate, we demonstrate that high miR-30 levels are protective against DOX toxicity and correlate this in turn with lower reactive oxygen species generation. In addition, we identify GATA-6 as a mediator of DOX-associated reductions in miR-30 expression. In conclusion, we describe that DOX causes acute and sustained miR-30 downregulation in cardiomyocytes via GATA-6. miR-30 overexpression protects cardiac cells from DOX-induced apoptosis, and its maintenance represents a potential cardioprotective and anti-tumorigenic strategy for anthracyclines.

G protein-coupled receptors in cardiac biology: old and new receptors

G protein-coupled receptors (GPCRs) are seven-transmembrane-spanning proteins that mediate cellular and physiological responses. They are critical for cardiovascular function and are targeted for the treatment of hypertension and heart failure. Nevertheless, current therapies only target a small fraction of the cardiac GPCR repertoire, indicating that there are many opportunities to investigate unappreciated aspects of heart biology. Here, we offer an update on the contemporary view of GPCRs and the complexities of their signalling, and review the roles of the 'classical' GPCRs in cardiovascular physiology and disease. We then provide insights into other GPCRs that have been less extensively studied in the heart, including orphan, odorant and taste receptors. We contend that these novel cardiac GPCRs contribute to heart function in health and disease and thereby offer exciting opportunities to therapeutically modulate heart function.

Independent predictor factors of supine tachycardia in patients with type 2 diabetes mellitus

INTRODUCTION

Supine tachycardia, frequently encountered in diabetic patients, is usually considered as an isolated diabetic complication in cardiac autonomic neuropathy. The objective of this study was to determine independent predictor factors of supine tachycardia among the clinical characteristics of type 2 diabetes mellitus.

METHODS

This prospective study included type 2 diabetic patients. Supine tachycardia was considered as 10 minutes resting heart rate equal or higher than 80 beats/minutes. According to presence or not of supine tachycardia, two groups were identified: tachycardia diabetic patients and none tachycardia diabetic patients. Cardiovascular autonomic tests: deep breathing, hand-grip, and mental stress tests and blood tests were performed in all patients. Statistical analysis was done using the Student's t-test, and univariate and multivariate logistic regression analysis.

RESULTS

We included 91 patients. The vagal response measured by the deep breathing test was 24.5 ± 5.7% in tachycardia diabetic patients vs 35.6 ± 6.8% in none tachycardia diabetic patients (P=0.007). The odds of supine tachycardia increased with serum creatinine (OR=1.350, 95% CI: 1.065-1.712, P=0.013) and serum uric acid levels (OR=1.034, 95% CI: 1.005-1.064, P=0.02) respectively, in diabetic patients. The prevalence of moderate renal failure was 45.5% in tachycardia diabetic patients vs. 21.6% in none tachycardia diabetic patients (P=0.034).

CONCLUSION

A high frequency of supine tachycardia in type 2 diabetic patients was significantly related with an impairment of the parasympathetic nervous system but other independent predictor factors were associated to the occurrence of this supine tachycardia, such as higher levels of serum creatinine and uric acid and moderate renal failure.

Clinical utility of fixed-dose combinations in hypertension: evidence for the potential of nebivolol/valsartan

Despite significant advances in pharmacologic approaches to treat hypertension during the last decades, hypertension- and hypertension-related organ damage are still a high health and economic burden because a large proportion of patients with hypertension do not achieve optimal blood pressure control. There is now general agreement that combination therapy with two or more antihypertensive drugs is required for targeted blood pressure accomplishment and reduction of global cardiovascular risk. The goals of combination therapies are to reduce long-term cardiovascular events by targeting different mechanism underlying hypertension and target organ disease, to block the counterregulatory pathways activated by monotherapies, to improve tolerability and decrease the adverse effects of up-titrated single agents, and to increase persistence and adherence with antihypertensive therapy. Multiple clinical trials provide evidence that fixed-dose combinations in a single pill offer several advantages when compared with loose-dose combinations. This review discusses the advances in hypertension control and associated cardiovascular disease as they relate to the prospect of combination therapy targeting a third-generation beta (β) 1-adrenergic receptor (nebivolol) and an angiotensin II receptor blocker (valsartan) in fixed-dose single-pill formulations.

Chronic activation of the low affinity site of β1-adrenoceptors stimulates haemodynamics but exacerbates pressure-overload cardiac remodelling

BACKGROUND AND PURPOSE

The β1-adrenoceptor has at least two binding sites, high and low affinity sites (β1H and β1L, respectively), which mediate cardiostimulation. While β1H-adrenoceptor can be blocked by all clinically used β-blockers, β1L-adrenoceptor is relatively resistant to blockade. Thus, chronic β1L-adrenoceptor activation may mediate persistent cardiostimulation, despite the concurrent blockade of β1H-adrenoceptors. Hence, it is important to determine the potential significance of β1L-adrenoceptors in vivo, particularly in pathological situations.

EXPERIMENTAL APPROACH

C57Bl/6 male mice were used. Chronic (4 or 8 weeks) β1L-adrenoceptor activation was achieved by treatment, via osmotic mini pumps, with (-)-CGP12177 (10 mg·kg(-1)·day(-1)). Cardiac function was assessed by echocardiography and micromanometry.

KEY RESULTS

(-)-CGP12177 treatment of healthy mice increased heart rate and left ventricular (LV) contractility. (-)-CGP12177 treatment of mice subjected to transverse aorta constriction (TAC), during weeks 4-8 or 4-12 after TAC, led to a positive inotropic effect and exacerbated fibrogenic signalling while cardiac hypertrophy tended to be more severe. (-)-CGP12177 treatment of mice with TAC also exacerbated the myocardial expression of hypertrophic, fibrogenic and inflammatory genes compared to untreated TAC mice. Washout of (-)-CGP12177 revealed a more pronounced cardiac dysfunction after 12 weeks of TAC.

CONCLUSIONS AND IMPLICATIONS

β1L-adrenoceptor activation provides functional support to the heart, in both normal and pathological (pressure overload) situations. Sustained β1L-adrenoceptor activation in the diseased heart exacerbates LV remodelling and therefore may promote disease progression from compensatory hypertrophy to heart failure.