Effect of metoprolol on myocardial function and energetics in patients with nonischemic dilated cardiomyopathy: a randomized, double-blind, placebo-controlled study

Comparative Efficacy of Different Drugs for the Treatment of Dilated Cardiomyopathy: A Systematic Review and Network Meta-analysis

BACKGROUND AND OBJECTIVE

At present, the therapies of dilated cardiomyopathy concentrated on the symptoms of heart failure and related complications. The study is to evaluate the clinical efficacy of a combination of various conventional and adjuvant drugs in treating dilated cardiomyopathy via network meta-analysis.

METHODS

The study was reported according to the PRISMA 2020 statement. From inception through 27 June 2022, the PubMed, Embase, Cochrane library, and Web of Science databases were searched for randomized controlled trials on medicines for treating dilated cardiomyopathy. The quality of the included studies was evaluated according to the Cochrane risk of bias assessment. R4.1.3 and Revman5.3 software were used for analysis.

RESULTS

There were 52 randomized controlled trials in this study, with a total of 25 medications and a sample size of 3048 cases. The network meta-analysis found that carvedilol, verapamil, and trimetazidine were the top three medicines for improving left ventricular ejection fraction (LVEF). Ivabradine, bucindolol, and verapamil were the top 3 drugs for improving left ventricular end-diastolic dimension (LVEDD). Ivabradine, L-thyroxine, and atorvastatin were the top 3 drugs for improving left ventricular end-systolic dimension (LVESD). Trimetazidine, pentoxifylline, and bucindolol were the top 3 drugs for improving the New York Heart Association classification (NYHA) cardiac function score. Ivabradine, carvedilol, and bucindolol were the top 3 drugs for reducing heart rate (HR).

CONCLUSION

A combination of different medications and conventional therapy may increase the clinical effectiveness of treating dilated cardiomyopathy. Beta-blockers, especially carvedilol, can improve ventricular remodeling, cardiac function, and clinical efficacy in patients with dilated cardiomyopathy (DCM). Hence, they can be used if patients tolerate them. If LVEF and HR do not meet the standard, ivabradine can also be used in combination with other treatments. However, since the quality and number of studies in our research were limited, large sample size, multi-center, and high-quality randomized controlled trials are required to corroborate our findings.

The Arrhythmogenicity of Sotalol and its Role in Heart Failure: A Literature Review

ABSTRACT

According to the American Heart Association, approximately 6 million adults have been afflicted with heart failure in the United States in 2020 and are more likely to have sudden cardiac death accounting for approximately 50% of the cause of mortality. Sotalol is a nonselective β-adrenergic receptor antagonist with class III antiarrhythmic properties that has been mostly used for atrial fibrillation treatment and suppressing recurrent ventricular tachyarrhythmias. The use of sotalol in patients with left ventricular dysfunction is not recommended by the American College of Cardiology or American Heart Association because studies are inconclusive with conflicting results regarding safety. This article aims to review the mechanism of action of sotalol, the β-blocking effects on heart failure, and provide an overview of clinical trials on sotalol use and its effects in patients with heart failure. Small- and large-scale clinical trials have been controversial and inconclusive about the use of sotalol in heart failure. Sotalol has been shown to reduce defibrillation energy requirements and reduce shocks from implantable cardioverter-defibrillators. Torsades de Pointes is the most life-threatening arrhythmia that has been documented with sotalol use and occurs more commonly in women and heart failure patients. Thus far, mortality benefits have not been demonstrated with sotalol use and larger multicenter studies are required going forward.

Novelties in the pharmacological approaches for chronic heart failure: new drugs and cardiovascular targets

Despite recent advances in chronic heart failure (HF) management, the prognosis of HF patients is poor. This highlights the need for researching new drugs targeting, beyond neurohumoral and hemodynamic modulation approach, such as cardiomyocyte metabolism, myocardial interstitium, intracellular regulation and NO-sGC pathway. In this review we report main novelties on new possible pharmacological targets for HF therapy, mainly on new drugs acting on cardiac metabolism, GCs-cGMP pathway, mitochondrial function and intracellular calcium dysregulation.

Heart Failure with Improved Ejection Fraction: Insight into the Variable Nature of Left Ventricular Systolic Function

The progress of contemporary cardiovascular therapy has led to improved survival in patients with myocardial disease. However, the development of heart failure (HF) represents a common clinical challenge, regardless of the underlying myocardial pathology, due to the severely impaired quality of life and increased mortality comparable with malignant neoplasms. Left ventricular ejection fraction (LVEF) is the main index of systolic function and a key predictor of mortality among HF patients, hence its improvement represents the main indicator of response to instituted therapy. The introduction of complex pharmacotherapy for HF, increased availability of cardiac-implantable electronic devices and advances in the management of secondary causes of HF, including arrhythmia-induced cardiomyopathy, have led to significant increase in the proportion of patients with prominent improvement or even normalization of LVEF, paving the way for the identification of a new subgroup of HF with an improved ejection fraction (HFimpEF). Accumulating data has indicated that these patients share far better long-term prognoses than patients with stable or worsening LVEF. Due to diverse HF aetiology, the prevalence of HFimpEF ranges from roughly 10 to 40%, while the search for reliable predictors and genetic associations corresponding with this clinical presentation is under way. As contemporary guidelines focus mainly on the management of HF patients with clearly defined LVEF, the present review aimed to characterize the definition, epidemiology, predictors, clinical significance and principles of therapy of patients with HFimpEF.

Targeting Myocardial Substrate Metabolism in the Failing Heart: Ready for Prime Time?

PURPOSE OF REVIEW

We review the clinical benefits of altering myocardial substrate metabolism in heart failure.

RECENT FINDINGS

Modulation of cardiac substrates (fatty acid, glucose, or ketone metabolism) offers a wide range of therapeutic possibilities which may be applicable to heart failure. Augmenting ketone oxidation seems to offer great promise as a new therapeutic modality in heart failure. The heart has long been recognized as metabolic omnivore, meaning it can utilize a variety of energy substrates to maintain adequate ATP production. The adult heart uses fatty acid as a major fuel source, but it can also derive energy from other substrates including glucose and ketone, and to some extent pyruvate, lactate, and amino acids. However, cardiomyocytes of the failing heart endure remarkable metabolic remodeling including a shift in substrate utilization and reduced ATP production, which account for cardiac remodeling and dysfunction. Research to understand the implication of myocardial metabolic perturbation in heart failure has grown in recent years, and this has raised interest in targeting myocardial substrate metabolism for heart failure therapy. Due to the interdependency between different pathways, the main therapeutic metabolic approaches include inhibiting fatty acid uptake/fatty acid oxidation, reducing circulating fatty acid levels, increasing glucose oxidation, and augmenting ketone oxidation.

Obstructive sleep apnea is associated with depressed myocardial mechanoenergetics

PURPOSE

To evaluate the association between the myocardial mechanoenergetic efficiency index (MEEi) and the Apnea-Hypopnea Index (AHI) in the initial phase of obstructive sleep apnea (OSA) diagnosis.

METHODS

In this cohort study, we included a total of 382 eligible participants without cardiovascular disease in a tertiary outpatient clinic between January 2013 and January 2015. We recorded demographic, clinical, polysomnographic and echocardiographic variables of the patients. In addition, myocardial mechanoenergetic efficiency (MEE) and MEEi were calculated by an echocardiography-derived validated measurement.

RESULTS

The mean (±SD) age of the participants was 48.47 ± 12.13, and male/female ratio was 287/95. Comparing with non-OSA, MEEi was significantly lower in OSA patients at all stages (0.35 ± 0.08 vs. 0.42 ± 0.05; p < .001). MEEi was negatively correlated with hypertension (r = -0.518, p < .001), body mass index (r = -0.382, p < .001), AHI (r = -0.656, p < .001), total apne (r = -0.525, p < .001), hypopnea (r = -0.415, p < .001), systolic pulmonary pressure (r = -0.318, p < .001), relative wall thickness (RWT; r = -0.415, p < .001), and positive correlated with left ventricular ejection fraction (r = 0.586, p < .001). According to multiple linear regression analysis AHI (β = -0.625, p < .001), total apnea (β = -0.402, p = .001), hypopnea (β = -0.395, p = .001), LV ejection fraction (β = 0.478, p < .001) and RWT (β = -0.279, p < .001) have an independent relationship with MEEi.

CONCLUSIONS

MEEi was lower in OSA patients. A reduced MEEi may reflect a disturbance in energy use of the myocardium. Consequently, our results may provide insight into the mechanisms leading to structural cardiac diseases in OSA patients.

Design and rationale for a comparison study of Olmesartan and Valsartan On myocardial metabolism In patients with Dilated cardiomyopathy (OVOID) trial: study protocol for a randomized controlled trial

BACKGROUND

Dilated cardiomyopathy (DCMP) is characterized by ventricular chamber enlargement and systolic dysfunction which may cause heart failure. Patients with DCMP have overactivation of the renin-angiotensin-aldosterone systems, which can also adversely affect myocardial metabolism in heart failure. The impairment of myocardial metabolism can contribute to the progression of left ventricular remodeling and contractile dysfunction in heart failure. Although angiotensin II receptor blockers (ARBs) have been used to treat patients with DCMP, there has been no direct comparison of the efficacy of these agents. The objective of this study is to compare the effects of olmesartan and valsartan on myocardial metabolism in patients with DCMP.

METHODS/DESIGN

The OVOID study (a comparison study of Olmesartan and Valsartan On myocardial metabolism In patients with Dilated cardiomyopathy) is designed as a non-blinded, open-label, parallel-group, prospective, randomized, controlled, multicenter clinical trial. A total of 40 DCMP patients aged between 20 and 85 years will be randomly allocated into the olmesartan or the valsartan group. ¹⁸F-fluoro-2-deoxyglucose (FDG) cardiac positron emission tomography (PET) will be performed at baseline and six months after receiving the study agent. The primary endpoint is myocardial glucose consumption per square meter, measured using ¹⁸F-FDG PET 6 months after receiving the study agent.

DISCUSSION

The purpose of this trial is to compare the efficacy between olmesartan and valsartan in improving myocardial metabolism in DCMP patients. This will be the first randomized comparative study investigating the differential effects of ARBs on heart failure.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04174456 . Registered on 18 November 2019.

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.

Targeting Adrenergic Receptors in Metabolic Therapies for Heart Failure

The heart has a reduced capacity to generate sufficient energy when failing, resulting in an energy-starved condition with diminished functions. Studies have identified numerous changes in metabolic pathways in the failing heart that result in reduced oxidation of both glucose and fatty acid substrates, defects in mitochondrial functions and oxidative phosphorylation, and inefficient substrate utilization for the ATP that is produced. Recent early-phase clinical studies indicate that inhibitors of fatty acid oxidation and antioxidants that target the mitochondria may improve heart function during failure by increasing compensatory glucose oxidation. Adrenergic receptors (α₁ and β) are a key sympathetic nervous system regulator that controls cardiac function. β-AR blockers are an established treatment for heart failure and α_1A-AR agonists have potential therapeutic benefit. Besides regulating inotropy and chronotropy, α₁- and β-adrenergic receptors also regulate metabolic functions in the heart that underlie many cardiac benefits. This review will highlight recent studies that describe how adrenergic receptor-mediated metabolic pathways may be able to restore cardiac energetics to non-failing levels that may offer promising therapeutic strategies.

The Role of Nonglycolytic Glucose Metabolism in Myocardial Recovery Upon Mechanical Unloading and Circulatory Support in Chronic Heart Failure

BACKGROUND

Significant improvements in myocardial structure and function have been reported in some patients with advanced heart failure (termed responders [R]) following left ventricular assist device (LVAD)-induced mechanical unloading. This therapeutic strategy may alter myocardial energy metabolism in a manner that reverses the deleterious metabolic adaptations of the failing heart. Specifically, our previous work demonstrated a post-LVAD dissociation of glycolysis and oxidative-phosphorylation characterized by induction of glycolysis without subsequent increase in pyruvate oxidation through the tricarboxylic acid cycle. The underlying mechanisms responsible for this dissociation are not well understood. We hypothesized that the accumulated glycolytic intermediates are channeled into cardioprotective and repair pathways, such as the pentose-phosphate pathway and 1-carbon metabolism, which may mediate myocardial recovery in R.

METHODS

We prospectively obtained paired left ventricular apical myocardial tissue from nonfailing donor hearts as well as R and nonresponders at LVAD implantation (pre-LVAD) and transplantation (post-LVAD). We conducted protein expression and metabolite profiling and evaluated mitochondrial structure using electron microscopy.

RESULTS

Western blot analysis shows significant increase in rate-limiting enzymes of pentose-phosphate pathway and 1-carbon metabolism in post-LVAD R (post-R) as compared with post-LVAD nonresponders (post-NR). The metabolite levels of these enzyme substrates, such as sedoheptulose-6-phosphate (pentose phosphate pathway) and serine and glycine (1-carbon metabolism) were also decreased in Post-R. Furthermore, post-R had significantly higher reduced nicotinamide adenine dinucleotide phosphate levels, reduced reactive oxygen species levels, improved mitochondrial density, and enhanced glycosylation of the extracellular matrix protein, α-dystroglycan, all consistent with enhanced pentose-phosphate pathway and 1-carbon metabolism that correlated with the observed myocardial recovery.

CONCLUSIONS

The recovering heart appears to direct glycolytic metabolites into pentose-phosphate pathway and 1-carbon metabolism, which could contribute to cardioprotection by generating reduced nicotinamide adenine dinucleotide phosphate to enhance biosynthesis and by reducing oxidative stress. These findings provide further insights into mechanisms responsible for the beneficial effect of glycolysis induction during the recovery of failing human hearts after mechanical unloading.

Myocardial Efficiency: A Fundamental Physiological Concept on the Verge of Clinical Impact

Myocardial external efficiency is the relation of mechanical energy generated by the left (or right) ventricle to the consumed chemical energy from aerobic metabolism. Efficiency can be calculated invasively, and, more importantly, noninvasively by using positron emission tomography, providing a single parameter by which to judge the adequacy of myocardial metabolism to generated mechanical output. This parameter has been found to be impaired in heart failure of myocardial or valvular etiology, and it changes in a characteristic manner with medical or interventional cardiac therapy. The authors discuss the concept, strengths, and limitations, known applications, and future perspectives of the use of myocardial efficiency.

Cardiac Resynchronisation Therapy and Cellular Bioenergetics: Effects Beyond Chamber Mechanics

Cardiac resynchronisation therapy is a cornerstone in the treatment of advanced dyssynchronous heart failure. However, despite its widespread clinical application, precise mechanisms through which it exerts its beneficial effects remain elusive. Several studies have pointed to a metabolic component suggesting that, both in concert with alterations in chamber mechanics and independently of them, resynchronisation reverses detrimental changes to cellular metabolism, increasing energy efficiency and metabolic reserve. These actions could partially account for the existence of responders that improve functionally but not echocardiographically. This article will attempt to summarise key components of cardiomyocyte metabolism in health and heart failure, with a focus on the dyssynchronous variant. Both chamber mechanics-related and -unrelated pathways of resynchronisation effects on bioenergetics – stemming from the ultramicroscopic level – and a possible common underlying mechanism relating mechanosensing to metabolism through the cytoskeleton will be presented. Improved insights regarding the cellular and molecular effects of resynchronisation on bioenergetics will promote our understanding of non-response, optimal device programming and lead to better patient care.

Vagus nerve stimulation for the treatment of heart failure

Heart failure (HF) is one of the most prevalent cardiovascular diseases and is associated with high morbidity and mortality. Mechanistically, HF is characterized by an overactive sympathetic nervous system and parasympathetic withdrawal, and this autonomic imbalance contributes to the progression of the disease. As such, modulation of autonomic nervous system by device-based therapy is an attractive treatment target. In this review, we discuss the role of autonomic nervous system dysfunction in the pathogenesis of HF and present the available evidence regarding vagus nerve stimulation for HF, with special emphasis on optimization of stimulation parameters. Finally, we discuss future avenues of research for neuromodulation in patients with HF.

Congestive Heart Failure in Children

Congestive heart failure is a final common clinical pathway for several diseases in childhood, such as familial cardiomyopathy, viral myocarditis, inborn errors of metabolism, and autoimmune disorders. Early identification and treatment can reduce symptom severity and may affect outcomes. In this review, the clinical characteristics of pediatric heart failure are described, and the initial diagnostic evaluation is outlined. Evidence-based heart failure treatment strategies at various clinical stages are discussed in detail, including the management of acute decompensated heart failure.

Test-retest repeatability of myocardial oxidative metabolism and efficiency using standalone dynamic 11C-acetate PET and multimodality approaches in healthy controls

BACKGROUND

Myocardial efficiency measured by 11C-acetate positron emission tomography (PET) has successfully been used in clinical research to quantify mechanoenergetic coupling. The objective of this study was to establish the repeatability of myocardial external efficiency (MEE) and work metabolic index (WMI) by non-invasive concepts.

METHODS AND RESULTS

Ten healthy volunteers (63 ± 4 years) were examined twice, one week apart, using 11C-acetate PET, cardiovascular magnetic resonance (CMR), and echocardiography. Myocardial oxygen consumption from PET was combined with stroke work data from CMR, echocardiography, or PET to obtain MEE and WMI for each modality. Repeatability was estimated as the coefficient of variation (CV) between test and retest. MEECMR, MEEEcho, and MEEPET values were 21.9 ± 2.7%, 16.4 ± 3.7%, and 23.8 ± 4.9%, respectively, P < .001. WMICMR, WMIEcho, and WMIPET values were 4.42 ± 0.90, 4.07 ± 0.63, and 4.58 ± 1.13 mmHg × mL/m2 × 106, respectively, P = .45. Repeatability for MEECMR was superior compared with MEEEcho but did not differ significantly compared with MEEPET (6.3% vs 12.9% and 9.4%, P = .04 and .25). CV values for WMICMR, WMIEcho, and WMIPET were 10.0%, 14.8%, and 12.0%, respectively, (P = .53).

CONCLUSIONS

Non-invasive measurements of MEE using 11C-acetate PET are highly repeatable. A PET-only approach did not differ significantly from CMR/PET and might facilitate further clinical research due to lower costs and broader applicability.

Myocardial metabolism in heart failure: Purinergic signalling and other metabolic concepts

Despite significant therapeutic advances in heart failure (HF) therapy, the morbidity and mortality associated with this disease remains unacceptably high. The concept of metabolic dysfunction as an important underlying mechanism in HF is well established. Cardiac function is inextricably linked to metabolism, with dysregulation of cardiac metabolism pathways implicated in a range of cardiac complications, including HF. Modulation of cardiac metabolism has therefore become an attractive clinical target. Cardiac metabolism is based on the integration of adenosine triphosphate (ATP) production and utilization pathways. ATP itself impacts the heart not only by providing energy, but also represents a central element in the purinergic signaling pathway, which has received considerable attention in recent years. Furthermore, novel drugs that have received interest in HF include angiotensin receptor blocker-neprilysin inhibitor (ARNi) and sodium glucose cotransporter 2 (SGLT-2) inhibitors, whose favorable cardiovascular profile has been at least partly attributed to their effects on metabolism. This review, describes the major metabolic pathways and concepts of the healthy heart (including fatty acid oxidation, glycolysis, Krebs cycle, Randle cycle, and purinergic signaling) and their dysregulation in the progression to HF (including ketone and amino acid metabolism). The cardiac implications of HF comorbidities, including metabolic syndrome, diabetes mellitus and cachexia are also discussed. Finally, the impact of current HF and diabetes therapies on cardiac metabolism pathways and the relevance of this knowledge for current clinical practice is discussed. Targeting cardiac metabolism may have utility for the future treatment of patients with HF, complementing current approaches.

Impact of Heart Rate Reduction with Maximal Tolerable Dose of Bisoprolol on Left Ventricular Reverse Remodeling

BACKGROUND

We aimed to evaluate effect of heart rate (HR) reduction on left ventricular reverse remodeling (LVRR) in Korean patients with heart failure with reduced ejection fraction (HFrEF).

METHODS

Ambulatory patients with HFrEF, who had paired echocardiograms, N-terminal prohormone brain natriuretic peptide (NT-proBNP), and global assessment score (GAS) at baseline and 6-month (n = 157), were followed up on preset treatment schedule with bisoprolol.

RESULTS

The LVRR occurred in 49 patients (32%) at 6-month. In multivariable analysis, independent predictors associated with LVRR were use of anti-aldosterone agent (odds ratio [OR], 4.18; 95% confidence interval [CI], 1.80-9.71), young age (OR, 0.96; 95% CI, 0.92-0.99), high baseline HR (OR, 3.76; 95% CI, 1.40-10.10), and favorable baseline GAS (OR, 1.73; 95% CI, 1.06-2.81). Beneficial effect of bisoprolol, in terms of LVRR, NT-proBNP, and GAS, was remarkable in the high HR group (baseline HR ≥ 75 beats per minute [bpm]), which showed a large HR reduction.

CONCLUSION

High baseline HR (≥ 75 bpm) showed an association with LVRR and improvement of NT-proBNP and GAS in patients with HFrEF. This seems to be due to a large HR reduction after treatments with bisoprolol. Trial registry at www.ClinicalTrials.gov, NCT00749034.

Developing Drugs for Heart Failure With Reduced Ejection Fraction: What Have We Learned From Clinical Trials?

There remains a large unmet need for new therapies in the treatment of heart failure with reduced ejection fraction (HFrEF). In the early drug development phase, the therapeutic potential of a drug is not yet fully understood and trial endpoints other than mortality are needed to guide drug development decisions. While a true surrogate marker for mortality in heart failure (HF) remains elusive, the successes and failures of previous trials can reveal markers that support clinical Go/NoGo decisions.

Impact of metoprolol treatment on mental status of chronic heart failure patients with neuropsychiatric disorders

Background

Metoprolol treatment is well established for chronic heart failure (CHF) patients, but the central nervous system side effects are often a potential drawback.

Objective

To investigate the impact of metoprolol treatment on change in mental status of CHF patients with clinical psychological disorders (such as depression, anxiety, and burnout syndrome).

Methods

From February 2013 to April 2016, CHF patients with clinical mental disorders received metoprolol (23.75 or 47.5 mg, qd PO, dose escalated with 23.75 mg each time until target heart rate [HR] <70 bpm was achieved) at the Second Affiliated Hospital of Kunming Medical University. Mental status was assessed by means of the Hospital Anxiety and Depression Scale (HADS) and the Copenhagen Burnout Inventory (CBI) scale. The primary outcome assessed was change in mental status of patients post-metoprolol treatment and the association with reduction in HR achieved by metoprolol.

Results

A total of 154 patients (median age: 66.39 years; males: n=101) were divided into eight groups on the basis of their mental status. HR decreased significantly from baseline values in all the groups to <70 bpm in the 12th month, P≤0.0001. The HADS depression and CBI scores significantly increased from baseline throughout the study frame (P≤0.0001 for all groups), but a significant decrease in the HADS anxiety score was observed in patients with anxiety (P≤0.0001 for all groups). Regression analysis revealed no significant correlation in any of the groups between the HR reduction and the change in the HADS/CBI scores, except for a change in the CBI scores of CHF patients with depression (P=0.01), which was HR dependent.

Conclusion

Metoprolol treatment worsens the depressive and high burnout symptoms, but affords anxiolytic benefits independent of HR reduction in CHF patients with clinical mental disorders. Hence, physicians need to be vigilant while prescribing metoprolol in CHF patients who present with mental disorders.

A Review of the External Validity of Clinical Trials with Beta-Blockers in Heart Failure

BACKGROUND

Beta-blockers (BBs) are the mainstay prognostic medication for all stages of chronic heart failure (CHF). There are many classes of BBs, each of which has varying levels of evidence to support its efficacy in CHF. However, most CHF patients have one or more comorbid conditions such as diabetes, renal impairment, and/or atrial fibrillation. Patient enrollment to randomized controlled trials (RCTs) often excludes those with certain comorbidities, particularly if the symptoms are severe. Consequently, the extent to which evidence drawn from RCTs is generalizable to CHF patients has not been well described. Clinical guidelines also underrepresent this point by providing generic advice for all patients. The aim of this review is to examine the evidence to support the use of BBs in CHF patients with common comorbid conditions.

METHODS

We searched MEDLINE, PubMed, and the reference lists of reviews for RCTs, post hoc analyses, systematic reviews, and meta-analyses that report on use of BBs in CHF along with patient demographics and comorbidities.

RESULTS

In total, 38 studies from 28 RCTs were identified, which provided data on six BBs against placebo or head to head with another BB agent in ischemic and nonischemic cardiomyopathies. Several studies explored BBs in older patients. Female patients and non-Caucasian race were underrepresented in trials. End points were cardiovascular hospitalization and mortality. Comorbid diabetes, renal impairment, or atrial fibrillation was detailed; however, no reference to disease spectrum or management goals as a focus could be seen in any of the studies. In this sense, enrollment may have limited more severe grades of these comorbidities.

CONCLUSIONS

RCTs provide authoritative information for a spectrum of CHF presentations that support guidelines. RCTs may provide inadequate information for more heterogeneous CHF patient cohorts. Greater Phase IV research may be needed to fill this gap and inform guidelines for a more global patient population.

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.

Noninvasive Detection of Early Metabolic Left Ventricular Remodeling in Systemic Hypertension

OBJECTIVES

Hypertension (HTN) is a common cause of left ventricular hypertrophy (LVH). Sustained pressure overload induces a permanent myocardial switch from fatty-acid to glucose metabolism. In this study, we tested the hypothesis that metabolic remodeling, characterized by increased myocardial glucose uptake, precedes structural and functional remodeling in HTN-induced LVH.

METHODS

We recruited 31 patients: 11 with HTN only, 9 with HTN and LVH and 11 normotensive controls without LVH. Transthoracic echocardiography was performed to assess the function, mass, wall thickness and diastolic function of the left ventricle. Positron emission tomography imaging was performed, and the rate of myocardial 2-deoxy-2-[18F]fluoro-D-glucose uptake, Ki, was determined using a 3-compartment kinetic model.

RESULTS

The mean Ki values were significantly higher in HTN patients than in those with HTN and LVH (p < 0.001) and in controls (p = 0.003). The unexpected decrease in Ki with LVH may be secondary to a decreased Ki with diastolic dysfunction (DD), 0.039 ± 0.032 versus 0.072 ± 0.013 (p = 0.004). There was also a significant stepwise decrease in Ki with increasing DD grade (p = 0.04).

CONCLUSION

Glucose metabolic remodeling is detectable in hypertensive patients before the development of LVH. Furthermore, lower glucose uptake rates are observed in patients with DD. The mechanism for this last finding requires further investigation.

Cardiac energy metabolic alterations in pressure overload-induced left and right heart failure (2013 Grover Conference Series)

Pressure overload of the heart, such as seen with pulmonary hypertension and/or systemic hypertension, can result in cardiac hypertrophy and the eventual development of heart failure. The development of hypertrophy and heart failure is accompanied by numerous molecular changes in the heart, including alterations in cardiac energy metabolism. Under normal conditions, the high energy (adenosine triphosphate [ATP]) demands of the heart are primarily provided by the mitochondrial oxidation of fatty acids, carbohydrates (glucose and lactate), and ketones. In contrast, the hypertrophied failing heart is energy deficient because of its inability to produce adequate amounts of ATP. This can be attributed to a reduction in mitochondrial oxidative metabolism, with the heart becoming more reliant on glycolysis as a source of ATP production. If glycolysis is uncoupled from glucose oxidation, a decrease in cardiac efficiency can occur, which can contribute to the severity of heart failure due to pressure-overload hypertrophy. These metabolic changes are accompanied by alterations in the enzymes that are involved in the regulation of fatty acid and carbohydrate metabolism. It is now becoming clear that optimizing both energy production and the source of energy production are potential targets for pharmacological intervention aimed at improving cardiac function in the hypertrophied failing heart. In this review, we will focus on what alterations in energy metabolism occur in pressure overload induced left and right heart failure. We will also discuss potential targets and pharmacological approaches that can be used to treat heart failure occurring secondary to pulmonary hypertension and/or systemic hypertension.

A "PET" area of interest: myocardial metabolism in human systolic heart failure

Myocardial substrate metabolism provides the energy needed for cardiac contraction and relaxation. The normal adult heart uses predominantly fatty acids (FAs) as its primary fuel source. However, the heart can switch and use glucose (and to a lesser extent, ketones, lactate, as well as endogenous triglycerides and glycogen), depending on the metabolic milieu and superimposed conditions. FAs are not a wholly better fuel than glucose, but they do provide more energy per mole than glucose. Conversely, glucose is the more oxygen-efficient fuel. Studies in animal models of heart failure (HF) fairly consistently demonstrate a shift away from myocardial fatty acid metabolism and toward glucose metabolism. Studies in humans are less consistent. Some show the same metabolic switch away from FA metabolism but not all. This may be due to differences in the etiology of HF, sex-related differences, or other mitigating factors. For example, obesity, insulin resistance, and diabetes are all related to an increased risk of HF and may complicate or contribute to its development. However, these conditions are associated with increased FA metabolism. This review will discuss aspects of human heart metabolism in systolic dysfunction as measured by the noninvasive, quantitative method-positron emission tomography. Continued research in this area is vital if we are to ameliorate HF by manipulating heart metabolism with the aim of increasing energy production and/or efficiency.

β1-Adrenergic receptor blockade extends the life span of Drosophila and long-lived mice

Chronic treatment with β-adrenergic receptor (βAR) agonists increases mortality and morbidity while βAR antagonists (β-blockers) decrease all-cause mortality for those at risk of cardiac disease. Levels of sympathetic nervous system βAR agonists and βAR activity increase with age, and this increase may hasten the development of age-related mortality. Here, we show that β-blockers extend the life span of healthy metazoans. The β-blockers metoprolol and nebivolol, administered in food daily beginning at 12 months of age, significantly increase the mean and median life span of isocalorically fed, male C3B6F1 mice, by 10 and 6.4%, respectively (P < 0.05). Neither drug affected the weight or food intake of the mice, indicating that induced CR is not responsible for these effects, and that energy absorption and utilization are not altered by the drugs. Both β-blockers were investigated to control for their idiosyncratic, off-target effects. Metoprolol and nebivolol extended Drosophila life span, without affecting food intake or locomotion. Thus, βAR antagonists are capable of directly extending the life span of two widely divergent metazoans, suggesting that these effects are phylogenetically highly conserved. Thus, long-term use of β-blockers, which are generally well-tolerated, may enhance the longevity of healthy humans.

Pathogenesis of chronic cardiorenal syndrome: is there a role for oxidative stress?

Cardiorenal syndrome is a frequently encountered clinical condition when the dysfunction of either the heart or kidneys amplifies the failure progression of the other organ. Complex biochemical, hormonal and hemodynamic mechanisms underlie the development of cardiorenal syndrome. Both in vitro and experimental studies have identified several dysregulated pathways in heart failure and in chronic kidney disease that lead to increased oxidative stress. A decrease in mitochondrial oxidative metabolism has been reported in cardiomyocytes during heart failure. This is balanced by a compensatory increase in glucose uptake and glycolysis with consequent decrease in myocardial ATP content. In the kidneys, both NADPH oxidase and mitochondrial metabolism are important sources of TGF-β1-induced cellular ROS. NOX-dependent oxidative activation of transcription factors such as NF-kB and c-jun leads to increased expression of renal target genes (phospholipaseA2, MCP-1 and CSF-1, COX-2), thus contributing to renal interstitial fibrosis and inflammation. In the present article, we postulate that, besides contributing to both cardiac and renal dysfunction, increased oxidative stress may also play a crucial role in cardiorenal syndrome development and progression. In particular, an imbalance between the renin-angiotensin-aldosterone system, the sympathetic nervous system, and inflammation may favour cardiorenal syndrome through an excessive oxidative stress production. This article also discusses novel therapeutic strategies for their potential use in the treatment of patients affected by cardiorenal syndrome.

β-Blockers in heart failure: benefits of β-blockers according to varying male proportions of study patients

BACKGROUND

In patients with heart failure (HF), b-blockers reduce mortality. It's not known whether the beneficial effects of the b-blockers were associated with the differing male proportions of study patients. It also remains to be clarified regarding the true beneficial effects of the 3 b-blockers recommended by the guideline on mortality in the real world.

HYPOTHESIS

The benefits of b-blockers in HF patients were sex-related different.

METHODS

Randomized, placebo controlled clinical trials were included if they evaluated the beneficial effects of the three b-blockers on mortality and on hospital admissions on an intention-to-treat basis, and lasted at least 3 months.

RESULTS

Twenty-eighty trials with 14,829 patients were included. The b-blockers significantly reduced all cause mortality by 29.6%, cardiac death by 29.8%, sudden death by 49.4%, respectively. The magnitude of benefits of b-blockers in HF patients was increased with the increased male proportion. A similar magnitude of reduction in all cause mortality was observed among the three b blockers. A trend toward to reduced cardiac death was observed among the three b blockers, but only in bisoprolol was this statistically different (RR, 0.72; 95%CI, [0.59-0.87]). Metoprolol was significantly superior to carvedilol (P = 0.008) or bisoprolol (P = 0.034) in reduced sudden death.

CONCLUSIONS

In patients with HF, the 3 commonly used b-blockers significantly reduced mortality. Greater benefits of b-blockers were observed in the higher male proportion studies. The metoprolol was significantly superior to carvedilol or bisoprolol in reduced sudden death. Additional trials are required to determine whether the benefits of b-blockers will be observed in female HF patients.

Parallel effects of β-adrenoceptor blockade on cardiac function and fatty acid oxidation in the diabetic heart: Confronting the maze

Diabetic cardiomyopathy is a disease process in which diabetes produces a direct and continuous myocardial insult even in the absence of ischemic, hypertensive or valvular disease. The β-blocking agents bisoprolol, carvedilol and metoprolol have been shown in large-scale randomized controlled trials to reduce heart failure mortality. In this review, we summarize the results of our studies investigating the effects of β-blocking agents on cardiac function and metabolism in diabetic heart failure, and the complex inter-related mechanisms involved. Metoprolol inhibits fatty acid oxidation at the mitochondrial level but does not prevent lipotoxicity; its beneficial effects are more likely to be due to pro-survival effects of chronic treatment. These studies have expanded our understanding of the range of effects produced by β-adrenergic blockade and show how interconnected the signaling pathways of function and metabolism are in the heart. Although our initial hypothesis that inhibition of fatty acid oxidation would be a key mechanism of action was disproved, unexpected results led us to some intriguing regulatory mechanisms of cardiac metabolism. The first was upstream stimulatory factor-2-mediated repression of transcriptional master regulator PGC-1α, most likely occurring as a consequence of the improved function; it is unclear whether this effect is unique to β-blockers, although repression of carnitine palmitoyltransferase (CPT)-1 has not been reported with other drugs which improve function. The second was the identification of a range of covalent modifications which can regulate CPT-1 directly, mediated by a signalome at the level of the mitochondria. We also identified an important interaction between β-adrenergic signaling and caveolins, which may be a key mechanism of action of β-adrenergic blockade. Our experience with this labyrinthine signaling web illustrates that initial hypotheses and anticipated directions do not have to be right in order to open up meaningful directions or reveal new information.

Metabolic remodelling in human heart failure

In addition to the typical abnormalities in myocardial structure and function, it is well established that the cardiac metabolism is abnormal in patients with heart failure (HF). Insulin resistance is a common co-morbidity in HF patients and also modulates cardiac metabolism in HF. The notion that an altered myocardial metabolism may contribute to the disease pathogenesis and optimizing it may serve therapeutic purposes underscores the importance of identifying the metabolic characteristics of HF patients. In this paper, the literature on the metabolic changes in human HF is reviewed, and the effects of metabolic modulators on patients with HF are discussed.

Modulating fatty acid oxidation in heart failure

In the advanced stages of heart failure, many key enzymes involved in myocardial energy substrate metabolism display various degrees of down-regulation. The net effect of the altered metabolic phenotype consists of reduced cardiac fatty oxidation, increased glycolysis and glucose oxidation, and rigidity of the metabolic response to changes in workload. Is this metabolic shift an adaptive mechanism that protects the heart or a maladaptive process that accelerates structural and functional derangement? The question remains open; however, the metabolic remodelling of the failing heart has induced a number of investigators to test the hypothesis that pharmacological modulation of myocardial substrate utilization might prove therapeutically advantageous. The present review addresses the effects of indirect and direct modulators of fatty acid (FA) oxidation, which are the best pharmacological agents available to date for 'metabolic therapy' of failing hearts. Evidence for the efficacy of therapeutic strategies based on modulators of FA metabolism is mixed, pointing to the possibility that the molecular/biochemical alterations induced by these pharmacological agents are more complex than originally thought. Much remains to be understood; however, the beneficial effects of molecules such as perhexiline and trimetazidine in small clinical trials indicate that this promising therapeutic strategy is worthy of further pursuit.

Targeting fatty acid and carbohydrate oxidation--a novel therapeutic intervention in the ischemic and failing heart

Cardiac ischemia and its consequences including heart failure, which itself has emerged as the leading cause of morbidity and mortality in developed countries are accompanied by complex alterations in myocardial energy substrate metabolism. In contrast to the normal heart, where fatty acid and glucose metabolism are tightly regulated, the dynamic relationship between fatty acid β-oxidation and glucose oxidation is perturbed in ischemic and ischemic-reperfused hearts, as well as in the failing heart. These metabolic alterations negatively impact both cardiac efficiency and function. Specifically there is an increased reliance on glycolysis during ischemia and fatty acid β-oxidation during reperfusion following ischemia as sources of adenosine triphosphate (ATP) production. Depending on the severity of heart failure, the contribution of overall myocardial oxidative metabolism (fatty acid β-oxidation and glucose oxidation) to adenosine triphosphate production can be depressed, while that of glycolysis can be increased. Nonetheless, the balance between fatty acid β-oxidation and glucose oxidation is amenable to pharmacological intervention at multiple levels of each metabolic pathway. This review will focus on the pathways of cardiac fatty acid and glucose metabolism, and the metabolic phenotypes of ischemic and ischemic/reperfused hearts, as well as the metabolic phenotype of the failing heart. Furthermore, as energy substrate metabolism has emerged as a novel therapeutic intervention in these cardiac pathologies, this review will describe the mechanistic bases and rationale for the use of pharmacological agents that modify energy substrate metabolism to improve cardiac function in the ischemic and failing heart. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.

Race, sex, and age differences in heart failure-related hospitalizations in a southern state: implications for prevention

BACKGROUND

Because heart failure (HF) is the final common pathway for most heart diseases, we examined its 10-year prevalence trend by race, sex, and age in Tennessee.

METHODS AND RESULTS

HF hospitalization data from the Tennessee Hospital Discharge Data System were analyzed by race, sex, and age. Rates were directly age-adjusted using the Year 2000 standard population. Adult (age 20+ years) inpatient hospitalization for primary diagnosis of HF (HFPD) increased from 4.2% in 1997 to 4.5% in 2006. Age-adjusted hospitalization for HF (per 10 000 population) rose by 11.3% (from 29.3 in 1997 to 32.6 in 2006). Parallel changes in secondary HF admissions were also noted. Age-adjusted rates were higher among blacks than whites and higher among men than women. The ratios of black to white by sex admitted with HFPD in 2006 were highest (9:1) among the youngest age categories (20 to 34 and 35 to 44 years). Furthermore, for each age category of black men below 65 years, there were higher HF admission rates than for white men in the immediate older age category. In 2006, the adjusted rate ratios for HFPD in black to white men ages 20 to 34 and 35 to 44 years were odds ratio, 4.75; 95% confidence interval, 3.29 to 6.86 and odds ratio, 5.10; 95% confidence interval, 4.15 to 6.25, respectively. Hypertension was the independent predictor of HF admissions in black men ages 20 to 34 years.

CONCLUSIONS

The higher occurrence of HF among young adults in general, particularly among young black men, highlights the need for prevention by identifying modifiable biological and social determinants to reduce cardiovascular health disparities in this vulnerable group.

Is target dose of beta-blocker more important than achieved heart rate or heart rate change in patients with systolic chronic heart failure?

Beta-blockers (BBs) are mandatory therapy for patients with systolic chronic heart failure (CHF). However, it is uncertain whether target dose of these agents is more important than the achievement of target heart rate (HR) in maximizing the benefits of these agents. To test this, we obtained ECG absolute HR from patients with systolic CHF, together with consecutive left ventricular ejection fraction (EF) measures at least 3 months apart. Patients were divided into those who achieved target dose for beta-blocker and/or target absolute HR of < or = 60 beats per minute (bpm) and target change in HR (>10 bpm reduction) with increasing dose. Baseline ejection fraction (EF) was similar across all groups. Patients with absolute or change in HR at target achieved a greater change in EF than those not at target (P= 0.027 and P= 0.012, respectively). In contrast, those who achieved target dose did not achieve a significantly greater improvement in EF than those not at target dose (P= 0.81). Similarly for absolute EF, patients at target HR or target change in HR achieved a greater EF increase than those achieving target dose. Based on these data, target HR or change in HR appears to be more critical to improvement in EF than target dose in CHF patients. Therefore, achieving an absolute HR or change in HR with BBs may be more important than target dose in maximizing benefits of BBs in this setting.

Energetics and metabolism in the failing heart: important but poorly understood

PURPOSE OF REVIEW

Profound abnormalities in myocardial energy metabolism occur in heart failure and correlate with clinical symptoms and survival. Available comprehensive human metabolic data come from small studies, enrolling patients across heart failure causes, at different disease stages, and using different methodologies, and is often contradictory. Remaining fundamental gaps in knowledge include whether observed shifts in cardiac substrate utilization are adaptive or maladaptive, causal or an epiphenomenon of heart failure.

RECENT FINDINGS

Recent studies have characterized the temporal changes in myocardial substrate metabolism involved in progression of heart failure, the role of insulin resistance, and the mechanisms of mitochondrial dysfunction in heart failure. The concept of metabolic inflexibility has been proposed to explain the lack of energetic and mechanical reserve in the failing heart.

SUMMARY

Despite current therapies, which provide substantial benefits to patients, heart failure remains a progressive disease, and new approaches to treatment are necessary. Developing metabolic interventions would be facilitated by systems-level integration of current knowledge on myocardial metabolic control. Although preliminary evidence suggests that metabolic modulators inducing a shift towards carbohydrate utilization seem generally beneficial in the failing heart, such interventions should be matched to the stage of metabolic deregulation in the progression of heart failure.

Myocardial fatty acid metabolism in health and disease

There is a constant high demand for energy to sustain the continuous contractile activity of the heart, which is met primarily by the beta-oxidation of long-chain fatty acids. The control of fatty acid beta-oxidation is complex and is aimed at ensuring that the supply and oxidation of the fatty acids is sufficient to meet the energy demands of the heart. The metabolism of fatty acids via beta-oxidation is not regulated in isolation; rather, it occurs in response to alterations in contractile work, the presence of competing substrates (i.e., glucose, lactate, ketones, amino acids), changes in hormonal milieu, and limitations in oxygen supply. Alterations in fatty acid metabolism can contribute to cardiac pathology. For instance, the excessive uptake and beta-oxidation of fatty acids in obesity and diabetes can compromise cardiac function. Furthermore, alterations in fatty acid beta-oxidation both during and after ischemia and in the failing heart can also contribute to cardiac pathology. This paper reviews the regulation of myocardial fatty acid beta-oxidation and how alterations in fatty acid beta-oxidation can contribute to heart disease. The implications of inhibiting fatty acid beta-oxidation as a potential novel therapeutic approach for the treatment of various forms of heart disease are also discussed.