Endothelin in human congestive heart failure

New insights into the mechanism of action of endothelin-1 on cerebral microcirculation

EVALUATION OF: Faraco G, Moraga A, Moore J, Anrather J, Pickel VM, Iadecola C. Circulating endothelin-1 alters critical mechanisms regulating cerebral microcirculation. Hypertension 62(4), 759–766 (2013). This article reviews a study by Faraco and colleagues that attempts to elucidate the mechanism of modulation of the cerebral blood flow by endothelin (ET) 1. ET1 is one of the most powerful vasoconstrictors and plays an important role in cerebrovascular disease and traumatic brain injury. However, the details of the mechanism of action of ET1 are still unknown. The study used a mouse model with a skull window through which the cortical cerebral blood flow was measured with a laser Doppler probe while various agents were applied. The role of reactive oxygen species and integrity of the blood–brain barrier were also assessed. In addition, the location of the ET receptor was determined by incubation of cortex samples with specific antibodies. ET1 increased mean arterial pressure and attenuated the cerebral blood flow increase stimulated by neuronal activity or the endothelium-dependent acethylcholine but not by A23187. ET1 suppresses the endothelial production of nitric oxide by modulating the endothelial nitric oxide synthase phosphorylation through Rho-associated protein kinase. This effect was mediated by an ETA receptor coupled to phospholipase C via GTP-binding protein and was not related to oxidative stress. The ETA receptor was found in the smooth muscle cells of the pial arterioles and cerebral endothelial cells. The resultant vascular dysfunction may increase the risk of brain ischemia by attenuating the cerebrovascular reserve. Improved understanding of the mechanism of action of ET1 on cerebral microcirculation is likely to stimulate the development of new and promising pharmacological targets.

The heart as an endocrine organ

The concept of the heart as an endocrine organ arises from the observation that the atrial cardiomyocytes in the mammalian heart display a phenotype that is partly that of endocrine cells. Investigations carried out between 1971 and 1983 characterised, by virtue of its natriuretic properties, a polypeptide referred to atrial natriuretic factor (ANF). Another polypeptide isolated from brain in 1988, brain natriuretic peptide (BNP), was subsequently characterised as a second hormone produced by the mammalian heart atria. These peptides were associated with the maintenance of extracellular fluid volume and blood pressure. Later work demonstrated a plethora of other properties for ANF and BNP, now designated cardiac natriuretic peptides (cNPs). In addition to the cNPs, other polypeptide hormones are expressed in the heart that likely act upon the myocardium in a paracrine or autocrine fashion. These include the C-type natriuretic peptide, adrenomedullin, proadrenomedullin N-terminal peptide and endothelin-1. Expression and secretion of ANF and BNP are increased in various cardiovascular pathologies and their levels in blood are used in the diagnosis and prognosis of cardiovascular disease. In addition, therapeutic uses for these peptides or related substances have been found. In all, the discovery of the endocrine heart provided a shift from the classical functional paradigm of the heart that regarded this organ solely as a blood pump to one that regards this organ as self-regulating its workload humorally and that also influences the function of several other organs that control cardiovascular function.

Circulating endothelin-1 alters critical mechanisms regulating cerebral microcirculation

Endothelin-1 (ET1) is a potent vasoconstrictor peptide implicated in the cerebrovascular alterations occurring in stroke, subarachnoid hemorrhage, and brain trauma. Brain or circulating levels of ET1 are elevated in these conditions and in risk factors for cerebrovascular diseases. Most studies on the cerebrovascular effects of ET1 have focused on vascular smooth muscle constriction, and little is known about the effect of the peptide on cerebrovascular regulation. We tested the hypothesis that ET1 increases cerebrovascular risk by disrupting critical mechanisms regulating cerebral blood flow. Male C57Bl6/J mice equipped with a cranial window were infused intravenously with vehicle or ET1, and somatosensory cortex blood flow was assessed by laser Doppler flowmetry. ET1 infusion increased mean arterial pressure and attenuated the blood flow increase produced by neural activity (whisker stimulation) or neocortical application of the endothelium-dependent vasodilator acetylcholine but not A23187. The cerebrovascular effects of ET1 were abrogated by the ET(A) receptor antagonist BQ123 and were not related to vascular oxidative stress. Rather, the dysfunction was dependent on Rho-associated protein kinase activity. Furthermore, in vitro studies demonstrated that ET1 suppresses endothelial nitric oxide (NO) production, assessed by its metabolite nitrite, an effect associated with Rho-associated protein kinase-dependent changes in the phosphorylation state of endothelial NO synthase. Collectively, these novel observations demonstrate that increased ET1 plasma levels alter key regulatory mechanisms of the cerebral circulation by modulating endothelial NO synthase phosphorylation and NO production through Rho-associated protein kinase. The ET1-induced cerebrovascular dysfunction may increase cerebrovascular risk by lowering cerebrovascular reserves and increasing the vulnerability of the brain to cerebral ischemia.

Differential expression of the pro-natriuretic peptide convertases corin and furin in experimental heart failure and atrial fibrosis

In heart failure (HF), the cardiac hormone natriuretic peptides (NPs) atrial (ANP), B-type (BNP), and C-type (CNP) play a key role to protect cardiac remodeling. The proprotein convertases corin and furin process their respective pro-NPs into active NPs. Here we define in a canine model of HF furin and corin gene and protein expression in normal and failing left atrium (LA) or ventricle (LV) testing the hypothesis that the NP proproteins convertases production is altered in experimental HF. Experimental canine HF was produced by rapid right ventricular pacing for 10 days. NPs, furin, and corin mRNA expression were determined by quantitative RT-PCR. Protein concentration or expression was determined by immunostaining, radioimmunoassay, or Western blot. Furin and corin proteins were present in normal canine LA and LV myocardium and vasculature and in smooth muscle cells. In normal canines, expression of NPs was dominant in the atrium compared with the ventricle. In experimental early stage HF characterized with marked atrial fibrosis, ANP, BNP, and CNP mRNA, and protein concentrations were higher in HF LA but not HF LV compared with normals. In LA, corin mRNA and protein expressions in HF were lower, whereas furin mRNA and protein expressions were higher than normals. NPs and furin expressions were augmented in the atrium in experimental early stage HF and, conversely, corin mRNA and protein expressions were decreased with atrial remodeling. Selective changes of these NP convertases may have significance in the regulation of pro-NP processing and atrial remodeling in early stage HF.

Role of inflammation and endothelial dysfunction in the pathogenesis of cardiac syndrome X

Chest pain with normal coronary arteriograms represents a major diagnostic and therapeutic challenge to contemporary cardiology. Cardiac syndrome X (CSX), defined as typical angina-like chest pain, a positive response to exercise stress testing and normal coronary arteriograms, encompasses patients with a variety of pathogenic mechanisms. Cardiac ischemia has been documented in approximately 25% of CSX patients and is associated with endothelial dysfunction and microvascular vasodilator abnormalities. Increased endothelin-1, a powerful vasoconstrictor, has been suggested to play a pathogenic role. There is a high prevalence of postmenopausal women with CSX and thus estrogen deficiency has also been proposed to represent a possible pathogenic mechanism. Inflammatory mechanisms and endothelial dysfunction at the coronary microvascular level appear to be important in the pathogenesis of CSX. Treatment with agents that have protective effects on the vasculature and also anti-inflammatory properties, such as statins and angiotensin-converting enzyme inhibitors have been effective in improving both symptoms and electrocardiographic signs of myocardial ischemia in patients with CSX. This review discusses the roles for endothelial dysfunction and inflammation in the pathogenesis of CSX, as well as the potential therapeutic implications of these mechanisms.

Neurohormonal activity and vascular properties late after aortic coarctation repair

BACKGROUND

Coarctation of aorta (CoA) patients present cardiovascular complications late after repair the causes of which are not fully understood. Our study investigates the neurohormonal and immune activation and the elastic properties of the aorta and peripheral vessels in adult patients with coarctation of aorta (CoA), late after repair.

METHODS

Nineteen adult patients with repaired CoA and 29 matched healthy controls underwent aortic distensibility, stiffness index, a study of the elastic properties of peripheral vessels proximal to the coarctation site and measurement of plasma cytokine and neurohormone levels.

RESULTS

Distensibility index was reduced (p=0.02) and stiffness index was increased (p=0.005) in CoA patients compared to control. Augmentation index (p=0.0007) and augmented pressure (p=0.001) were higher in CoA patients and Forearm Blood Flow (FBF) index was reduced (p=0.009). Plasma levels of sICAM-1 (p=0.01), sVCAM-1 (p=0.05), E-selectin (p=0.01), sFas-ligand (p=0.02) and IL-10 (p=0.01) were also elevated in CoA patients vs control. TNF-a, IL-6, Endothelin-1 and NT-pro-BNP levels were not.

CONCLUSIONS

Adults with repaired CoA seem to develop a late inflammatory reaction, which reflects a functional problem in all vessels, regardless of the initial lesion. This may explain the late complications of the disease despite early repair and improved surgical procedures.

Ambient temperature and biomarkers of heart failure: a repeated measures analysis

BACKGROUND

Extreme temperatures have been associated with hospitalization and death among individuals with heart failure, but few studies have explored the underlying mechanisms.

OBJECTIVES

We hypothesized that outdoor temperature in the Boston, Massachusetts, area (1- to 4-day moving averages) would be associated with higher levels of biomarkers of inflammation and myocyte injury in a repeated-measures study of individuals with stable heart failure.

METHODS

We analyzed data from a completed clinical trial that randomized 100 patients to 12 weeks of tai chi classes or to time-matched education control. B-type natriuretic peptide (BNP), C-reactive protein (CRP), and tumor necrosis factor (TNF) were measured at baseline, 6 weeks, and 12 weeks. Endothelin-1 was measured at baseline and 12 weeks. We used fixed effects models to evaluate associations with measures of temperature that were adjusted for time-varying covariates.

RESULTS

Higher apparent temperature was associated with higher levels of BNP beginning with 2-day moving averages and reached statistical significance for 3- and 4-day moving averages. CRP results followed a similar pattern but were delayed by 1 day. A 5°C change in 3- and 4-day moving averages of apparent temperature was associated with 11.3% [95% confidence interval (CI): 1.1, 22.5; p = 0.03) and 11.4% (95% CI: 1.2, 22.5; p = 0.03) higher BNP. A 5°C change in the 4-day moving average of apparent temperature was associated with 21.6% (95% CI: 2.5, 44.2; p = 0.03) higher CRP. No clear associations with TNF or endothelin-1 were observed.

CONCLUSIONS

Among patients undergoing treatment for heart failure, we observed positive associations between temperature and both BNP and CRP-predictors of heart failure prognosis and severity.

PKC-ε mediates multiple endothelin-1 actions on systolic Ca2+ and contractility in ventricular myocytes

Endothelin-1 (ET-1) induces positive inotropy (enhanced contractility) in cardiac muscle, but establishing underlying cellular mechanisms has been controversial in part because of a growing number of signaling pathways and end effectors targeted by ET-1. Here we present evidence that ET-1 induces positive inotropism in ventricular tissue by increasing both systolic Ca2+ and myofilament Ca2+ sensitivity. To examine the roles of PKC-δ and PKC-ε in these acute responses to ET-1, kinase inactive dominant negative PKC (dn-PKC) constructs were expressed in adult rat ventricular myocytes. Yellow fluorescent protein (YFP) was fused to dn-PKC constructs to visualize expression and localization of dn-PKC in living myocytes. Due to an alanine to glutamate mutation in the pseudosubstrate site, dn-PKCs constitutively translocated to anchoring sites and were unaffected by agonist or phorbol ester treatment. Dn-PKC-δ-YFP mainly distributed at Z-lines and at intercalated disks in adult myocytes, whereas dn-PKC-ε-YFP stained the surface sarcolemma, T-tubules/Z-lines and perinuclear region. Myocytes expressing dn-PKC-δ-YFP showed normal systolic Ca2+ and contractile responses to ET-1. In contrast, the entire ensemble of ET-1 responses was blocked in myocytes expressing dn-PKC-ε-YFP including increased Ca2+ transients, enhanced myofilament Ca2+ sensitivity, and positive inotropy. This report provides direct evidence that PKC-ε is activated early and robustly following ET-1 stimulation and thus mediates multiple intracellular changes underlying the acute actions of ET-1 on myocardium.

Biomarkers of endothelial dysfunction: can they help us deciphering systemic inflammation and sepsis?

The endothelial integrity, as mechanical barrier against microorganisms and as natural "anticoagulant", is crucial for physiologic organ function. Systemic activation of the endothelium upon inflammation, sepsis, and septic shock is always ending in blood-tissue barrier disruption. With increasing dysfunction, uncontrolled clotting activation, capillary microthrombi formation, tissue edema, local hypoxia, and ischemia are initiated. This in turn enhances a vicious circle leading to multiple organ failure and death. Therefore, biomarkers reflecting this special compartment may help in the early detection of systemic inflammation and its complications. This review provides an overview of the most important endothelial biomarkers and their possible use in sepsis.

Pulmonary hypertension related to left-sided cardiac pathology

Pulmonary hypertension (PH) is the end result of a variety of diverse pathologic processes. The chronic elevation in pulmonary artery pressure often leads to right ventricular pressure overload and subsequent right ventricular failure. In patients with left-sided cardiac disease, PH is quite common and associated with increased morbidity and mortality. This article will review the literature as it pertains to the epidemiology, pathogenesis, and diagnosis of PH related to aortic valve disease, mitral valve disease, left ventricular systolic and diastolic dysfunction, and pulmonary veno-occlusive disease. Moreover, therapeutic strategies, which focus on treating the underlying cardiac pathology will be discussed.

Pharmacological treatment of chronic systolic heart failure: are we scraping the bottom of the barrel?

Heart failure is a major health problem and its prevalence is growing, primarily as a consequence of the aging of the population. Recently, we have witnessed significant progress in reducing the mortality associated with chronic heart failure due to the introduction of renin-angiotensin-aldosterone system inhibitors, beta-blocking agents and the use of electrical devices. However, the prognosis of heart failure is still so disappointing that it remains the leading cause of death in developed countries. This grim record impels the search for new therapeutic strategies. The objective of this paper is to briefly review the results of some recent trials that have been put in place to test the effects of drugs that are deemed to be potentially capable of improving the prognosis of chronic systolic heart failure patients. Despite compelling theoretical premises, the results to date appear to be weak or even disappointing.

ZFP260 is an inducer of cardiac hypertrophy and a nuclear mediator of endothelin-1 signaling

Pressure and volume overload induce hypertrophic growth of postnatal cardiomyocytes and genetic reprogramming characterized by reactivation of a subset of fetal genes. Despite intense efforts, the nuclear effectors of cardiomyocyte hypertrophy remain incompletely defined. Endothelin-1 (ET-1) plays an important role in cardiomyocyte growth and is involved in mediating the neurohormonal effects of mechanical stress. Here, we show that the phenylephrine-induced complex-1 (PEX1), also known as zinc finger transcription factor ZFP260, is essential for cardiomyocyte response to ET-1 as evidenced in cardiomyocytes with PEX1 knockdown. We found that ET-1 enhances PEX1 transcriptional activity via a PKC-dependent pathway which phosphorylates the protein and further potentiates its synergy with GATA4. Consistent with a role for PEX1 in cardiomyocyte hypertrophy, overexpression of PEX1 is sufficient to induce cardiomyocyte hypertrophy in vitro and in vivo. Importantly, transgenic mice with inducible PEX1 expression in the adult heart develop cardiac hypertrophy with preserved heart function. Together, the results identify a novel nuclear effector of ET-1 signaling and suggest that PEX1 may be a regulator of the early stages of cardiac hypertrophy.

Mechanisms involved in the effects of endothelin-1 in pig prostatic small arteries

Since endothelin-1 (ET-1) is involved in prostatic disorders, the current study investigated the mechanisms underlying the ET-1-induced effects in pig prostatic small arteries. The experiments were performed in rings mounted in microvascular myographs containing physiological saline solution at 37oC for isometric force recordings. On basal tension, ET-1 (0.1-30 nM) evoked concentration-dependent contractions, which were enhanced by endothelium removal. ET-1 contractions were inhibited by blockade of endothelin ETA and ETB receptors, extracellular Ca2+ removal and blockade of voltage-dependent (L-type)- and non-voltage-dependent-Ca2+ channels. On endothelium intact rings precontracted with noradrenaline, the ETB endothelin receptor agonist BQ3020 promoted a concentration-dependent relaxation which was reduced by blockade of ETB receptors, nitric oxide synthase, guanylyl cyclase and prostanoids synthesis. Endothelium removal abolished its relaxant response and unmasked a BQ3020-induced contraction. Tetraethylammonium and 4-aminopyridine, blockers of non-selective K+ channels and voltage-dependent K+ (Kv) channels, respectively, inhibited the relaxations to BQ3020. Iberiotoxin, apamin and glibenclamide, blockers of large and small Ca2+-activated- and ATP-dependent- K+ channels, respectively, failed to modify these responses. These data suggest that ET-1 promotes contraction of pig prostatic small arteries by activating vascular smooth muscle contractile endothelin ETA and ETB receptors coupled to extracellular Ca2+ entry, via voltage-dependent (L-type)- and non-voltage-dependent Ca2+ channels, also being due to intracellular Ca2+ mobilization. In addition, a population of endothelial ETB receptors mediates vasorelaxation via NO-cGMP pathway, vasodilator cyclooxygenase product(s) and Kv channels.

Increased expression of the endothelin system in arterial lesions from patients with giant-cell arteritis: association between elevated plasma endothelin levels and the development of ischaemic events

OBJECTIVE

Approximately 15-20% of patients with giant-cell arteritis (GCA) develop ischaemic complications often preceded by transient ischaemia. The expression of the endothelin (ET) system in GCA lesions was investigated to assess its relationship with the development of ischaemic complications.

METHODS

Plasma ET-1 was quantified by immunoassay in 61 patients with biopsy-confirmed GCA and 16 healthy donors. ET-1, endothelin-converting enzyme (ECE-1) and endothelin receptor (ET(A)R and ET(B)R) messenger RNA were measured by real-time quantitative reverse transcriptase-PCR in temporal arteries from 35 of these patients and 19 control arteries. Proteins were measured by immunoassay and Western blot.

RESULTS

ET-1 concentration was increased at the protein level in temporal artery samples from GCA patients compared with controls (0.98 (SEM 0.32) vs 0.28 (SEM 0.098) fmol/mg, p = 0.028). ECE-1, ET(A)R and ET(B)R/actin ratios (Western blot) were also significantly higher in GCA patients. Intriguingly, mRNA expression of ET-1, ECE-1 and both receptors was significantly reduced in GCA lesions compared with control arteries. When investigating mechanisms underlying these results, platelet-derived growth factor and IL-1beta, present in GCA lesions, were found to downregulate ET-1 mRNA in cultured human temporal artery-derived smooth muscle cells. Glucocorticoid treatment for 8 days did not result in significantly decreased endothelin tissue concentration (0.87 (SEM 0.2) vs 0.52 (SEM 0.08); p = 0.6). Plasma endothelin concentrations were higher in patients with ischaemic complications (1.049 (SEM 0.48) vs 1.205 (SEM 0.63) pg/ml, p = 0.032).

CONCLUSIONS

The endothelin system is increased at the protein level in GCA lesions creating a microenvironment prone to the development of ischaemic complications. Recovery induced by glucocorticoids is delayed, indicating persistent exposure to endothelin during initial treatment.

Large animal models of heart failure: a critical link in the translation of basic science to clinical practice

Congestive heart failure (HF) is a clinical syndrome, with hallmarks of fatigue and dyspnea, that continues to be highly prevalent and morbid. Because of the growing burden of HF as the population ages, the need to develop new pharmacological treatments and therapeutic interventions is of paramount importance. Common pathophysiologic features of HF include changes in left ventricle structure, function, and neurohormonal activation. The recapitulation of the HF phenotype in large animal models can allow for the translation of basic science discoveries into clinical therapies. Models of myocardial infarction/ischemia, ischemic cardiomyopathy, ventricular pressure and volume overload, and pacing-induced dilated cardiomyopathy have been created in dogs, pigs, and sheep for the investigation of HF and potential therapies. Large animal models recapitulating the clinical HF phenotype and translating basic science to clinical applications have successfully traveled the journey from bench to bedside. Undoubtedly, large animal models of HF will continue to play a crucial role in the elucidation of biological pathways involved in HF and the development and refinement of HF therapies.

Bosentan for pulmonary hypertension and other pulmonary diseases: emerging evidence

Endothelin-1 is a potent vasoconstrictor and mitogen that is primarily synthesized and released from vascular endothelial cells. Bosentan is a dual endothelin-receptor antagonist that initially received approval for treatment of WHO group I pulmonary arterial hypertension (PAH) for patients in functional classes III and IV. Analysis of a study conducted in functional class II patients (Endothelin Antagonist Trial in Mildly Symptomatic PAH Patients [EARLY] trial) suggest its efficacy for these less symptomatic patients. In addition, bosentan has demonstrated efficacy in patients with congenital heart disease and Eisenmengers syndrome with right to left shunting and in HIV-related PAH. Studies of bosentan in inoperable or residual chronic thromboembolic pulmonary hypertension suggest possible efficacy. Bosentan appears promising in patients with idiopathic pulmonary fibrosis who do not have pulmonary hypertension. Combinations of bosentan with other PAH therapies such as iloprost and sildenafil may have incremental benefit over monotherapy.

Myocardial protective effect of tezosentan, an endothelin receptor antagonist, for ischemia-reperfusion injury in experimental heart failure models

The myocardial protective effects of endothelin antagonist in ischemic cardiomyopathy (ICMP), doxorubicin-induced cardiomyopathy (DOX) and pressure-overload hypertrophy by transverse aortic constriction (TAC) models have been predicted to be different. The objective of this experiment, therefore, is to evaluate the myocardial protective effect of tezosentan, an endothelin receptor antagonist, in various experimental heart failure models. Sprague-Dawley rats (6-8 weeks old, 200-300 g) were randomized to three experimental groups (n=30 each): ICMP; DOX; and TAC group. Each of these groups was randomly assigned further to the following subgroups (n=10 each): sham-operated ischemia-reperfusion subgroup (SHAM); tezosentan treated ischemia-reperfusion subgroup (Tezo); and tezosentan non-treated ischemia-reperfusion subgroup (N-Tezo). Total circulatory arrest was induced for 1 hr, followed by 2 hr of reperfusion. The left ventricular developed pressure, peak positive and negative first derivatives, and coronary blood flow were significantly different (P<0.05) among the SHAM, Tezo, and N-Tezo subgroups of the ICMP group at 30 min of reperfusion, but there were no statistically significant differences among the subgroups of the DOX and TAC groups. In conclusion, tezosentan, an endothelin receptor antagonist, showed myocardial protection effects only on the ischemic cardiomyopathy rat model, but not in the non-ischemic heart failure rat models.

Cardioprotective signaling by endothelin

The endothelin axis promotes vasoconstriction, suggesting that antagonists of endothelin signaling might be useful in treatment of heart failure. However, promising results from animal trials have not been recapitulated in heart failure patients. Here we review the role of major signaling pathways in the heart that are involved in cell survival initiated by ET-1. These pathways include mitogen-activated protein kinase, phosphatidyl inositol-1,4,5-triphosphate kinase (PI3K-AKT), nuclear factor-kappaB (NF-kappaB), and calcineurin signaling. A better understanding of endothelin-mediated signaling in cardiac cell survival may allow a reevaluation of endothelin receptor antagonists (ETRAs) in the treatment of heart failure.

B-type natriuretic peptide and C-terminal-pro-endothelin-1 for the prediction of severely impaired peak oxygen consumption

OBJECTIVE

To assess the utility of B-type natriuretic peptide (BNP) and C-terminal-pro-endothelin-1 (CT-proET-1) to predict a severely impaired peak oxygen consumption (peak VO(2), < 14 mL kg(-1) min(-1)) in patients referred for cardiopulmonary exercise testing.

DESIGN

Cross-sectional study.

SETTING

Tertiary care center.

METHODS

Peak VO(2), BNP and CT-proET-1 were assessed in 141 consecutive patients referred for cardiopulmonary exercise testing.

RESULTS

B-type natriuretic peptide [median (interquartile range) 48 (38-319) vs. 33 (15-86) pg mL(-1); P = 0.002] and CT-proET-1 [87 (76-95) vs. 60 (52-74) pmol L(-1); P < 0.001] were higher in patients with a peak VO(2) < 14 mL kg(-1) min(-1) (n = 30) than in those with a peak VO(2) > or = 14 mL kg(-1) min(-1) (n = 111). CT-pro-ET-1 had a higher area under the receiver-operator-characteristics curve (AUC) to predict a peak VO(2) < 14 mL kg(-1) min(-1) than BNP (0.79 vs. 0.68; P = 0.04). The optimal BNP cut-off of 37.2 pg mL(-1) had a sensitivity of 80% and a specificity of 56%. The optimal CT-proET-1 cut-off of 74.4 pmol L(-1) had a sensitivity of 80% and specificity of 76%. A five-item score composed of body mass index, diabetes, forced expiratory volume within the first second, alveolo-arterial oxygen pressure difference, and BNP had an AUC of 0.88 to predict a peak VO(2) < 14 mL kg(-1) min(-1). Adding CT-proET-1 to the score resulted in an AUC of 0.92.

CONCLUSIONS

C-terminal-pro-endothelin-1 is superior to BNP for the prediction of a peak VO(2) < 14 mL kg(-1) min(-1) in patients referred for CPET. A score incorporating body mass index, diabetes status, spirometry, blood gases, BNP and CT-proET-1 improves the prediction of a peak VO(2) < 14 mL kg(-1) min(-1) based on single biomarkers.

Endothelin downregulates SERCA2 gene and protein expression in adult rat ventricular myocytes: regulation by pertussis toxin-sensitive Gi protein and cAMP

Downregulation of the sarcoplasmic reticulum calcium ATPase (SERCA2) is associated with diastolic dysfunction in the failing heart. Elevated plasma endothelin-1 (ET) levels are correlated with congestive heart failure suggesting that ET may play a pathophysiological role. We have investigated the ability of ET to regulate SERCA2 gene expression in isolated adult rat ventricular myocytes. We find that ET enhances net protein synthesis by approximately 40% but significantly downregulates SERCA2 mRNA expression, time dependently, by approximately 30-50%, and the expression of SERCA2 protein by approximately 50%. In myoyctes, ET binds to ET(A) receptor that couples to G(q) and G(i) proteins. Inhibition of G(q)-PLC-induced phosphoinositide (PI) hydrolysis with U73122 (1 muM) or inhibition of G(i) protein with pertussis toxin (PTX) abolishes the ability of ET to downregulate SERCA2 mRNA gene expression. Further investigation suggests that ET coupling to PTX-sensitive G(i) with consequent lowering of cAMP is required for downregulation of SERCA2 mRNA levels. Increasing intracellular cAMP quantity using cAMP-specific PDE inhibitor Ro20-1724 or cAMP analog dibutyryl-cAMP reverses ET-induced downregulation of SERCA2 mRNA levels. The data indicate that, in adult myocytes, ET downregulates SERCA2 mRNA and protein levels, and the effect requires cross-talk between G(q) and PTX-sensitive G(i) pathways.

Pharmacogenetic effect of an endothelin-1 haplotype on response to bucindolol therapy in chronic heart failure

BACKGROUND

Beta-blocker therapy has become a mainstay therapy for the over 5 million patients with chronic heart failure in the United States. Variation in clinical response to beta-blockers is a well-known phenomenon and may be because of genetic differences between patients. We hypothesized that variation in genes of the endothelin system mediate the clinical response to beta-blockers in heart failure.

METHODS

Single nucleotide polymorphisms (SNPs) in six endothelin system genes were genotyped in 309 heart failure patients in a randomized trial of bucindolol versus placebo therapy. We adjusted for multiple comparisons and tested for association between genotype and time to two prospective endpoints.

RESULTS

Nine SNPs were sufficiently common to undergo statistical analysis. The SNPs had no significant effect on prospective outcomes in the placebo group, or on the primary endpoint of time to death in either arm. Two SNPs (IVS-4 G/A and Lys198Asn) in the endothelin-1 gene, however, predicted time to the combined endpoint of heart failure hospitalization or all-cause death in bucindolol-treated patients. The alleles at these SNPs were in tight linkage disequilibrium appearing on either of two complementary haplotypes. A 'dose-response' trend was observed, with participants carrying the rarer haplotype having the highest hazard ratios as compared to the relative 'protective' effect of the common haplotype.

CONCLUSION

A common endothelin-1 gene haplotype may be a pharmacogenetic predictor of a favorable clinical response to beta-blocker therapy in heart failure patients. The existence of a less common 'high-risk' haplotype could identify a subpopulation of heart failure patients destined to respond poorly to beta-blocker therapies.

Pulmonary hypertension secondary to left ventricular systolic dysfunction: contemporary diagnosis and management

Pulmonary hypertension secondary to left ventricular systolic dysfunction is often a poor prognostic marker in chronic heart failure. In this article, we review evidence supporting modern strategies addressing pulmonary hypertension in patients with left ventricular systolic dysfunction, including right-sided heart catheterization with vasoreactivity testing and subsequent parenteral, oral, and inhaled therapy. We delineate a diagnostic approach to secondary pulmonary hypertension and outline evidence-based therapeutic strategies for management in acute and chronic heart failure.

Antagonism of endothelin-1 inhibits hypoxia-induced apoptosis in cardiomyocytes

Apoptosis is well documented to be a common feature of many pathological processes of the heart. Exogenous endothelin-1 (ET-1) has been shown to be proapoptotic or antiapoptotic, depending on ET-1 concentration, cell type, and the ratio of ETA/ETB receptor subtypes. The role of endogenous ET-1 in cardiomyocyte apoptosis, however, is not clarified. This study observed the effects of the ETA-receptor antagonists BQ610 and BQ123 and the ETB-receptor antagonist BQ788 on hypoxia-induced apoptosis in primary cultured neonatal rat cardiomyocytes. Hypoxic apoptosis was induced by incubating cardiomyocytes in serum-free medium under 3% O2 and 5% CO2 for 24 h and evaluated by TUNEL analysis and flow cytometry. TUNEL analysis showed that the apoptotic cardiomyocytes constituted 24.2% +/- 2.2% of the total cells under hypoxic conditions. Treatment with BQ610 (5 micromol/L) significantly reduced the apoptosis rate to 13.2% +/- 3.7% (data from 4 independent experiments, p < 0.01 vs. hypoxia). Flow cytometry showed that the percentage of apoptotic cells positively stained with annexin V and propidium iodide was 42.76% +/- 4.44% (n = 12) in cultures subjected to hypoxia. BQ123 at 0.04, 0.2, and 1.0 micromol/L dose-dependently reduced the apoptosis rate to 34.00% +/- 10.35% (n = 6, p < 0.05), 30.38% +/- 8.28% (n = 6, p < 0.01), and 22.89% +/- 4.19% (n = 6, p < 0.01), respectively. In contrast, BQ788 did not affect hypoxic apoptosis. These findings suggested that endogenous ET-1 contributed to hypoxia-induced apoptosis in cultured cardiomyocytes, which was mediated by ETA receptors, but not by ETB receptors.

Cardiac toxicity of high-dose cyclophosphamide and melphalan in patients with multiple myeloma treated with tandem autologous hematopoietic stem cell transplantation

Tandem autologous hematopoetic stem cell transplantation (HSCT) is an effective treatment in patients with multiple myeloma (MM). Patients receive high-dose cyclophosphamide (CY) followed by two myeloablative dosages of melphalan (MEL). Cardiotoxicity treatment related data are scanty. In 30 patients with MM chemotherapy was followed by high-dose CY (cycle CY), and two autologous tandem HSCT treatments with MEL (cycles MEL I and MEL II). During each 15-day treatment troponin I (TnI), brain natriuretic peptide (BNP) and endothelin-1 (ET-1) were controlled at six time points. All patients underwent conventional and tissue Doppler echocardiography prior to CY therapy (Eho 0), before cycle MEL I (Eho 1), before cycle MEL II (Eho 2), and 3 months after the completion of therapy (Eho 3). None of the patients developed clinical signs of heart failure. The peak TnI concentrations were noted at days 8, 11, and 15 during all three chemotherapy cycles. During all three cycles there was a significant increase in baseline BNP concentrations and BNP levels measured at day 1 after treatment with CY and MEL (CY: P = 0.0001, MEL I: P = 0.001, MEL II: P = 0.001). The highest BNP concentration occurred during CY treatment (0.517 +/- 0.391 microg/L). During cycles MEL I and MEL II we noted the peak BNP concentrations at day 4 following chemotherapy (MEL I 0.376 +/- 0.418 microg/L; MEL II 0.363 +/- 0.379 microg/L). During all three cycles the highest ET-1 levels occurred at day 1 after chemotherapy (CY 1.146 +/- 1.313 ng/L; MEL I 1.054 +/- 2.242 ng/L; MEL II 0.618 +/- 0.539 ng/L). A significant increase in ET-1 concentrations relative to the basal values occurred only in cycle MEL II (P = 0.003). The duration of wave a in the Doppler pulmonary vein flow increased significantly (Eho 0/Eho 1: P = 0.008, Eho 0/Eho 3: P = 0.026). There was a significant decrease in the A/a ratio in flow velocities during chemotherapy (Eho 0/Eho 1: P = 0.002, Eho 0/Eho 3: P < 0.0001). Early diastolic tissue Doppler velocities (Em) decreased significantly during individual cycles of chemotherapy (P = 0.006). A significant post-treatment increase in the incidence of mitral regurgitation was observed (Eho 0/Eho 3: P = 0.003). Treatment of MM patients with tandem autologous HSCT is cardiotoxic. Our patients did not develop clinically overt heart failure or myocardial necrosis. Increased plasma levels of BNP and ET-1 were compatible with transient neurohormonal activation of heart failure. Doppler echocardiography studies revealed worsening of left ventricular diastolic function and occurrence of functional mitral regurgitation.

Long-term prognostic value of mid-regional pro-adrenomedullin and C-terminal pro-endothelin-1 in patients with acute myocardial infarction

BACKGROUND

Mid-regional pro-adrenomedullin (MR-proADM) and endothelin-1 have been shown to predict mortality of patients with acute myocardial infarction. However, the prognostic value of both biomarkers in predicting long-term clinical events after acute myocardial infarction remains unclear.

METHODS

In a prospective study, 30 patients suffering from acute ST elevation myocardial infarction or non-ST elevation myocardial infarction were enrolled. Measurements of MR-proADM and CT-pro-endothelin-1 (CT-proET-1) were performed at initial presentation, 2 or 3 days and 4 months after acute myocardial infarction. Long-term clinical events (e.g., recurrent myocardial infarction, percutaneous transluminal coronary angioplasty, aorto-coronary venous bypass or cardiogenic shock) were documented over a period from the 4th until the 10th month.

RESULTS

Both MR-proADM and CT-proET-1 were able to differentiate patients with subsequent long-term clinical events (n=11) from those without (n=19). At the time of acute myocardial infarction, median MR-proADM level of the event group was 0.69 nmol/L as compared to 0.59 nmol/L of the no-event group (p=0.036). A difference was still observed after 3 days (event group median 0.66 nmol/L; no-event group median 0.57 nmol/L; p=0.022). Accordingly, median CT-proET-1 level was 72.9 pmol/L in the event group as compared to a median of 54.4 pmol/L in patients in the no-event group (p=0.009) 3 days after acute myocardial infarction. Within the acute phase, patients with MR-proADM levels > or =0.67 nmol/L were 3 times more likely (relative risk 2.8; 95% confidence interval 1.2-6.9; p=0.042) to suffer from a future clinical event. The area under the curve (AUC) was 0.71 (95% confidence interval 0.51-0.86; p=0.046). After 3 days, patients with CT-proET-1 levels > or =57 pmol/L were 6 times more likely (relative risk 5.9; 95% confidence interval 0.9-40.4; p=0.036) to suffer from a future clinical event. The AUC was 0.76 (95% confidence interval 0.55-0.90; p=0.015).

CONCLUSIONS

Elevated levels of MR-proADM and CT-proET-1 during the acute phase of myocardial infarction may predict an adverse long-term clinical outcome.

Applying heart failure guidelines to adult congenital heart disease patients

There is a growing population of adult patients with congenital heart defects in the developed world. Most have been repaired, but few have been cured. Many have myocardial dysfunction. Most have exercise intolerance. Some have heart failure. As a group, they show neurohormonal activation similar to that seen in an adult heart failure population with acquired heart disease. Currently, the patients at greatest risk of heart failure are those without a systemic left ventricle, such as Mustard and Senning repairs of transposition of the great arteries (TGA), congenitally corrected TGA, and patients who have had a Fontan procedure. Exercise intolerance may predict hospitalization and death in such patients. For those patients with systemic left ventricles, it would seem reasonable to use the heart failure guidelines developed for patients with acquired heart disease. For those patients without a systemic left ventricle (e.g., a systemic right ventricle or single ventricle), there is currently no foundation for evidence-based therapy.

Cytokines and myocardial dysfunction: state of the art

BACKGROUND

Myocardial dysfunction has been associated with inflammation and cytokine modulation.

OBJECTIVES

The study objective was to understand the role of cytokines in the pathophysiology and management of myocardial dysfunction.

METHODS

Heart failure has been revisited with revision of the pertinent published articles in the Medline, Scopus, Cochrane Database of Systematic Reviews, and EBSCO Host research.

RESULTS

For the proinflammatory cytokines, illumination of this important point requires further diagnostic and therapeutic investigations. Data on chronic heart failure are not so reassuring; therefore, patients with advanced heart failure should not be treated with anticytokines at this time.

CONCLUSION

Further studies are warranted to pave the way for introducing cytokine and immunomodulation therapy at the optimal and appropriate time.

Prognostic markers in heart failure--congestion, neurohormones, and the cardiorenal syndrome

There are several markers of poor prognosis in heart failure (HF). The most established markers of poor prognosis in HF include neurohormonal (NH) imbalance, low ejection fraction (EF), ventricular arrhythmias, intraventricular conduction delays, low functional capacity, low SBP, and renal failure. The relative importance of these factors is unknown, as they have never been studied together. We present a 74-year-old female with nonischemic cardiomyopathy and an EF<20% who over 24 years since diagnosis, never developed clinical or hemodynamic congestion, was never hospitalized for HF, and never required a loop diuretic. She had all of the clinical indicators of poor prognosis in HF except for severe NH imbalance and renal failure, illustrating their importance in HF prognosis. While NH activation in HF is initially an adaptive mechanism, an imbalance of NH effectors causes congestion leading to a vicious cycle of congestion, renal dysfunction, and worsening of HF. The combination of NH activation and renal failure in HF is a vasomotor nephropathy known as the cardiorenal syndrome (CRS) and portends a poor prognosis. Pharmacological disruption of NH pathways early in HF may prevent CRS and, therefore, improve outcomes.

IP3 receptor-dependent Ca2+ release modulates excitation-contraction coupling in rabbit ventricular myocytes

Inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R)-dependent Ca(2+) signaling exerts positive inotropic, but also arrhythmogenic, effects on excitation-contraction coupling (ECC) in the atrial myocardium. The role of IP(3)R-dependent sarcoplasmic reticulum (SR) Ca(2+) release in ECC in the ventricular myocardium remains controversial. Here we investigated the role of this signaling pathway during ECC in isolated rabbit ventricular myocytes. Immunoblotting of proteins from ventricular myocytes showed expression of both type 2 and type 3 IP(3)R at levels approximately 3.5-fold less than in atrial myocytes. In permeabilized myocytes, direct application of IP(3) (10 microM) produced a transient 21% increase in the frequency of Ca(2+) sparks (P < 0.05). This increase was accompanied by a 13% decrease in spark amplitude (P < 0.05) and a 7% decrease in SR Ca(2+) load (P < 0.05) and was inhibited by IP(3)R antagonists 2-aminoethoxydiphenylborate (2-APB; 20 microM) and heparin (0.5 mg/ml). In intact myocytes endothelin-1 (100 nM) was used to stimulate IP(3) production and caused a 38% (P < 0.05) increase in the amplitude of action potential-induced (0.5 Hz, field stimulation) Ca(2+) transients. This effect was abolished by the IP(3)R antagonist 2-APB (2 microM) or by using adenoviral expression of an IP(3) affinity trap that buffers cellular IP(3). Together, these data suggest that in rabbit ventricular myocytes IP(3)R-dependent Ca(2+) release has positive inotropic effects on ECC by facilitating Ca(2+) release through ryanodine receptor clusters.

Role of endothelin-1 receptor antagonists in vasoconstriction mediated by endothelin and other vasoconstrictors in human internal mammary artery

BACKGROUND

The action of antagonists for endothelin type A (ET(A)) and type B (ET(B)) on the vasoconstriction mediated by various vasoconstrictors in the human bypass grafts have not been well-defined. We studied the role of antagonists for both ET(A) and ET(B) receptors in vasoconstriction mediated by endothelin-1 and other vasoconstrictors in the human internal mammary artery (IMA).

METHODS

Isolated IMA rings (n = 192, taken from 49 patients) were studied in organ bath for the interaction between endothelin-1, angiotensin II, U46619, and potassium chloride and the antagonist for ET(A) (BQ-123) or ET(B) (BQ-788).

RESULTS

Significant relaxations were observed by BQ-123 (agonist: endothelin-1, 84.9 +/- 7.9%; angiotensin II, 45.5 +/- 5.1%; and U46619, 30.7 +/- 5.7%) or BQ-788 (agonist: endothelin-1, 66.5 +/- 11.3%; angiotensin II, 38.9 +/- 4.2%; and U46619, 30.8 +/- 4.0%), but not to potassium chloride-induced precontraction. Incubation of IMA with BQ-123 or BQ-123 + BQ-788 significantly shifted the concentration-contraction curve to endothelin-1 rightward (p < 0.05 vs control) with effective concentration causing 50% of maximal response (EC50) (-7.59 +/- 0.04 or -7.81 +/- 0.05 vs -8.47 +/- 0.05 log M in the control, p < 0.001), whereas BQ-788 alone did not affect the contraction curve (p = 1.0 vs control). In contrast, none of the endothelin-1 inhibitors and the combination demonstrated significant depression effects on angiotensin II, U46619, or potassium chloride-induced contraction.

CONCLUSIONS

The present study demonstrates the role of ET(A) and ET(B) antagonists in the endothelin-1-mediated contraction in the human IMA and indicates the dominant role of ET(A) receptors. Although these effects are specific to endothelin-1, cross-action between endothelin-1 and angiotensin II exists. These findings provide useful knowledge for the future development of the clinical antispastic protocol in coronary bypass surgery.

C-terminal pro-endothelin-1 offers additional prognostic information in patients after acute myocardial infarction: Leicester Acute Myocardial Infarction Peptide (LAMP) Study

BACKGROUND

Endothelin-1 is elevated in heart failure (HF) and after acute myocardial infarction (AMI) and gives prognostic information on mortality. Another part of its precursor, C-terminal pro-endothelin-1 (CT-proET-1), is more stable in circulation and ex vivo. We investigated the cardiovascular prognostic value post-AMI of CT-proET-1 and compared it to N-terminal pro-B-type natriuretic peptide (NTproBNP), a marker of death and HF.

METHODS

We measured plasma CT-proET-1 and NTproBNP in 983 consecutive post-AMI patients (721 men, mean age 65.0 +/- [SD] 12.2 years), 3 to 5 days after chest pain onset.

RESULTS

There were 101 deaths and 49 readmissions with HF during follow-up (median 343, range 0-764 days). C-terminal pro-endothelin-1 was raised in patients with death or HF compared to survivors (median [range] [pmol/L], 119.0 [14.0-671.0] vs 73.0 [4.6-431.0], P < .0001). Using a Cox proportional hazards logistic model, log CT-proET-1 (HR 6.82) and log NTproBNP (HR 2.62) were significant independent predictors of death or HF (along with age, sex, history of AMI, and therapy with beta-blockers). The areas under the receiver operating curve for CT-proET-1, NTproBNP, and the logistic model with both markers were 0.76, 0.76, and 0.81 respectively. Findings were similar for death and HF as individual end points.

CONCLUSION

The endothelin system is known to be activated post AMI. C-terminal pro-endothelin-1 is a powerful predictor of adverse outcome, along with NTproBNP. CT-proET-1 may represent a clinically useful marker of prognosis after AMI.

Safety and efficacy of nesiritide in pediatric heart failure

BACKGROUND

We hypothesized that recombinant B-type natriuretic peptide (BNP) (nesiritide) could improve urine output and neurohormonal markers of heart failure without worsening renal function in pediatric patients.

METHODS AND RESULTS

We analyzed our experience involving 140 nesiritide infusions in 63 consecutive children. Serum levels of BNP and electrolytes were measured before and after therapy. Dosing was begun at 0.01 mcg.kg.min without a bolus and titrated to a maximum of 0.03 mcg.kg.min, in 0.005-mcg.kg.min increments. Blood pressure, heart rate, and heart rhythm were monitored. In a substudy, 20 patients with decompensated cardiomyopathy-related heart failure received 72 hours of nesiritide with prospective assessment of aldosterone, norepinephrine, plasma renin, and endothelin-1 levels before and after therapy. The heart rate decreased significantly (P = .001). Urine output increased significantly on Days 1 and 3 (P < or = .001 and .004, respectively). The mean serum creatinine level decreased from 1.135 to 1.007 mg/dL (P < or = .001). In the substudy, aldosterone levels decreased from 37.5 +/- 57.1 to 20.5 +/- 41.9 ng/dL (P = .005). Plasma renin, norepinephrine, and endothelin-1 levels decreased nonsignificantly. Two infusions were discontinued because of hypotension.

CONCLUSIONS

Nesiritide safely treated decompensated heart failure in children. Increased urine output reflected improving renal function. Improved neurohormonal markers were seen after 72 hours of therapy, and complications were uncommon.

Sepsis-induced myocardial dysfunction

Despite the fact that septic patients exhibit altered cardiac function, it is not considered a major pathology during sepsis. Thus, the molecular mechanisms underlying sepsis-induced myocardial dysfunction have not been studied extensively. In a polymicrobial septic rat model, +dP/dt and -dP/dt on day 1 were not altered but found depressed later, i.e., at 3 and 7 days postsepsis. Diastolic dysfunction characterized by an elevation of the time constant of left ventricular relaxation, tau, was evident at 1, 3, and 7 days postsepsis. Recent data from our laboratory demonstrated that sepsis-induced cardiodynamic alterations correlated with upregulation of TNF receptor-associated death domain, Bax, Smac (both mitochondrial and cytosolic fractions), total nuclear factor kappaB expression, p38-mitogen-activated protein kinase and c-Jun N-terminal kinase phosphorylation, and cytochrome c levels in the rat heart at 3 and 7 days postsepsis. Data from various laboratories emphasized that molecular myocardial alteration, which occurs during early and late stages of sepsis, needs to be elucidated thoroughly. A poor understanding of myocardial signaling during early sepsis could be one of the main reasons for limited success of pharmacotherapeutic options for sepsis. We anticipate that an increased understanding of pathophysiological mechanisms leading to sepsis-induced myocardial dysfunction would generate new enthusiasm among various research groups in this area of research.

Effect of exercise training on autonomic derangement and neurohumoral activation in chronic heart failure

BACKGROUND

In chronic heart failure (CHF), persistent autonomic derangement and neurohumoral activation cause structural end-organ damage, decrease exercise capacity, and reduce quality of life. Beneficial effects of pharmacotherapy and of exercise training in CHF have been documented at various functional and structural levels. However, pharmacologic treatment can not yet reduce autonomic derangement and neurohumoral activation in CHF to a minimum. Various studies suggest that exercise training is effective in this respect.

METHODS AND RESULTS

After reviewing the available evidence we conclude that exercise training increases baroreflex sensitivity and heart rate variability, and reduces sympathetic outflow, plasma levels of catecholamines, angiotensin II, vasopressin, and brain natriuretic peptides at rest.

CONCLUSIONS

Exercise training has direct and reflex sympathoinhibitory beneficial effects in CHF. The mechanism by which exercise training normalizes autonomic derangement and neurohumoral activation is to elucidate for further development of CHF-related training programs aimed at maximizing efficacy while minimizing workload.

Baseline and Serial Neurohormones in Patients With Congestive Heart Failure Treated With and Without Bucindolol: Results of the Neurohumoral Substudy of the Beta-Blocker Evaluation of Survival Study (BEST)

BACKGROUND

Serial neurohormones may serve as markers of efficacy of congestive heart failure (CHF) therapy. We measured serial plasma big-endothelin (Big-ET), ET-1, N-terminal atrial natriuretic peptide, and brain natriuretic peptide (BNP) in 206 patients randomized to bucindolol or placebo in Beta-Blocker Evaluation of Survival Trial (BEST).

METHODS AND RESULTS

Neurohormones were measured at baseline and 3 and 12 months. At baseline, BNP and Big-ET levels were greater in New York Heart Association (NYHA) Class IV than in Class III patients (median 122 pg/mL versus 447 pg/mL, P = .001; and 20.0 pg/mL versus 9.9 pg/mL, P = .003), and in patients with left ventricular ejection fraction (LVEF) < or = 20% compared with LVEF > 20% (median 211 pg/mL versus 99.1 pg/mL; and 12.9 pg/mL versus 8.0 pg/mL, both P = .003). Big-ET and BNP were the strongest predictors of the composite end point of CHF hospitalization or death. LVEF at 12 months correlated inversely with 12-month BNP levels (r = -0.41, P = .0001). Bucindolol had no effect on neurohormones except that bucindolol treated patients had lower Big-ET levels at 3 months than patients receiving placebo (median 9.1 pg/mL versus 10.9 pg/mL, P = .05). A decline in ET-1 was associated with increased risk of the composite endpoint.

CONCLUSIONS

Lack of effect of bucindolol on natriuretic peptide levels appears consistent with its overall lack of efficacy in BEST.