Review of current and investigational pharmacologic agents for acute heart failure syndromes

Universal and Sensitive Drug Assessment Biosensing Platform Using Optimal Mechanical Beating Detection of Single Cardiomyocyte

The preclinical assessment of efficacy and safety is essential for cardiovascular drug development in order to guarantee effective prevention and treatment of cardiovascular disease and avoid human health endangerment and a huge waste of resources. Rhythmic mechanical beating as one of the crucial cardiomyocyte properties has been exploited to establish a drug assessment biosensing platform. However, the conventional label-free biosensing platforms are difficult to perform high-throughput and high-resolution mechanical beating detection for a single cardiomyocyte, while label-based strategies are limited by pharmacologically adverse effects and phototoxicity. Herein, we propose a biosensing platform involving the multichannel electrode array device and the universal mechanical beating detection system. The platform can determine the optimal characteristic working frequency of different devices and dynamically interrogate the viability of multisite single cardiomyocytes to establish the optimized cell-based model for sensitive drug assessment. The subtle changes of mechanical beating signals induced by cardiovascular drugs can be detected by the platform, thereby demonstrating its high performance in pharmacological assessment. The universal and sensitive drug assessment biosensing platform is believed to be widely applied in cardiology investigating and preclinical drug screening.

Overexpression of Na+-HCO3- cotransporter contributes to the exacerbation of cardiac remodeling in mice with myocardial infarction by increasing intracellular calcium overload

The role of the cardiac isoform of the electrogenic sodium-bicarbonate ion cotransporter (NBCe1) in cardiac remodeling is not fully understood. The aim of this study was to assess the effects of NBCe1 overexpression on cardiac remodeling induced by myocardial infarction (MI) in mice. We generated NBCe1 transgenic (Tg) mice and NBCe1 overexpressing adult mouse ventricular myocytes (AMVMs) to investigate the role of NBCe1 on post-MI remodeling and calcium kinetics. Tg mice showed a markedly higher mortality rate and larger infarct size after MI. At 6 weeks after MI, the maximum rising rates of left ventricular pressure (dp/dt), contractility index, and the exponential time constant of relaxation (τ) were markedly lower, and there was higher cardiomyocyte apoptosis, in Tg mice compared with WT mice. In cultured AMVMs, overexpression of NBCe1 decreased sarcomere shortening and calcium amplitude. In WT AMVMs, the rates of the rise and decay phase of calcium transients, indicated by the rising time (T_peak, time to peak) and decay time constant (τ_d), and the number of apoptotic cells, were increased following hypoxia, while overexpression of NBCe1 further increased T_peak and cellular apoptosis, but not τ_d. Intracellular resting calcium and sodium concentrations were significantly increased following both hypoxia and NBCe1 overexpression. Co-treatment with S0859, an NBCe1 antagonist, blocked the hypoxia-induced increase in T_peak, τ_d, intracellular resting calcium and sodium concentrations, and apoptosis in cardiomyocytes. These findings indicate that NBCe1 overexpression promotes cardiac remodeling by increasing intracellular calcium overload. Therefore, NBCe1 should be a potential target for treatment of cardiac remodeling.

New arylsparteine derivatives as positive inotropic drugs

Positive inotropic agents are fundamental in the treatment of heart failure; however, their arrhythmogenic liability and the increased myocardial oxygen demand strongly limit their therapeutic utility. Pursuing our study on cardiovascular activities of lupin alkaloid derivatives, several 2-(4-substituted-phenyl)-2-dehydrosparteines and 2-(4-substituted-phenyl)sparteines were prepared and tested for inotropic and chronotropic activities on isolated guinea pig atria. Four compounds (6b, 6e, 7b, and 7f) exhibited significant inotropism that, at the higher concentrations, was followed by negative inotropism or toxicity. Compound 7e (2-(4-tolyl)sparteine) exhibited a steep dose-depending inotropic activity up to the highest concentration tested (300 µM) with an E_max of 116.5 ± 3.4% of basal force, proving less potent but much more active in comparison to the highest concentrations tested of digoxin and milrinone having E_max of 87.5 ± 3.1% and 52.2 ± 1.1%, respectively. Finally, docking studies suggested that the relevant sparteine derivatives could target the sigma-1 receptor, whose involvement in cardiac activity is well documented.

Rac1-PAK2 pathway is essential for zebrafish heart regeneration

P-21 activated kinases, or PAKs, are serine-threonine kinases that play important roles in diverse heart functions include heart development, cardiovascular development and function in a range of models; however, the mechanisms by which PAKs mediate heart regeneration are unknown. Here, we demonstrate that PAK2 and PAK4 expression is induced in cardiomyocytes and vessels, respectively, following zebrafish heart injury. Inhibition of PAK2 and PAK4 using a specific small molecule inhibitor impedes cardiomyocyte proliferation/dedifferentiation and cardiovascular regeneration, respectively. Cdc42 is specifically expressed in the ventricle and may function upstream of PAK2 but not PAK4 under normal conditions and that cardiomyocyte proliferentation during heart regeneration relies on Rac1-mediated activation of Pak2. Our results indicate that PAKs play a key role in heart regeneration.

Association of age and baseline systolic blood pressure with outcomes in patients hospitalized for acute heart failure syndromes

BACKGROUND

Baseline systolic blood pressure (SBP) is one of the most important prognostic indicators for patients with acute heart failure syndromes (AHFS). However, the association among age, baseline SBP, and outcomes of AHFS is unclear. This study was performed to evaluate the relation between baseline SBP and outcomes to increasing age in patients hospitalized for AHFS.

METHODS

Of the 4842 patients entered into the Acute Decompensated Heart Failure Syndromes (ATTEND) registry, 4828 patients with in-hospital and postdischarge follow-up data were included. The patients were divided into quartiles of age (<65, 65 to 75, 76 to 82, and ≥83 years), and each age group was divided into quartiles of baseline SBP. Then the 1-year all-cause mortality was compared among the baseline SBP quartiles in the each age quartile.

RESULTS

After adjustment for multiple comorbidities, patients aged <65 years, 65 to 75 years, and 76 to 82 years showed no significant increase in the relative risk of all-cause mortality as the baseline SBP declined until the lowest SBP quartile (SBP<112 mmHg, <120 mmHg, and <120 mmHg, respectively). In contrast, among patients aged ≥83 years, the lower three SBP quartiles (SBP<122 mmHg, 122 to <142 mmHg, and 142 to <165 mmHg) were associated with a significantly higher risk of all-cause mortality than the highest SBP quartile.

CONCLUSIONS

In patients hospitalized for AHFS, the relation between baseline SBP and all-cause mortality is markedly associated with increasing age, which means that baseline SBP is more important for very elderly patients with AHFS.

Tolvaptan in a pediatric patient with diuretic-resistant heart and kidney failure

Despite conventional diuretic therapy, volume overload persists in many patients with decompensated heart failure. Adverse effects of diuretics are common, including worsening kidney function and electrolyte disturbance. Furthermore, decreased kidney function also affects the response to diuretics and is associated with an increased risk of mortality. A 10-year-old boy with congestive heart failure (CHF) complicated by advanced chronic kidney disease (CKD) presented with oliguria and generalized edema. He was being treated with furosemide and spironolactone, and these doses were increased to 3 mg/kg/day after admission. Although edema decreased temporarily, the symptoms worsened and furosemide resistance developed 2 months later. Tolvaptan (0.1 mg/kg/day) was started, resulting in a gradual increase in the plasma sodium level and adequate decongestion of the volume overload state. Cardiac function also improved. The use of tolvaptan should be considered in pediatric cases of conventional diuretic-resistant CHF, even when complicated by advanced CKD.

Acute decompensated heart failure: evolving literature and implications for future practice

Acute decompensated heart failure (ADHF) is associated with substantial morbidity and mortality, and represents a considerable financial burden to society. Historically, few prospective, randomized, double-blinded trials have investigated the optimal management of ADHF, and most guideline recommendations are based primarily on expert opinion. However, in the last decade, a considerable amount of research has added to the understanding of the management of ADHF in both patients with fluid overload and low cardiac output. In addition, as mechanical circulatory support devices and heart transplantation continue to evolve, significant advances have also been made with regard to the proper selection of patients for advanced surgical options. Finally, several novel pharmacologic agents have shown promise in early trials and may represent the next steps in ADHF management. Although advances have been made over the past decade, many questions remain.

Current management and future directions for the treatment of patients hospitalized for heart failure with low blood pressure

Although patients hospitalized with heart failure have relatively low in-hospital mortality, the post-discharge rehospitalization and mortality rates remain high despite advances in treatment. Most patients admitted for heart failure have normal or high blood pressure, but 15-25 % have low systolic blood pressure with or without signs and/or symptoms of hypoperfusion. All pharmacological agents known to improve the prognosis of patients with heart failure also reduce blood pressure, and this limits their use in patients with heart failure and low blood pressure (HF-LBP). However, patients with HF-LBP have much higher in-hospital and post-discharge mortality. In these patients, a conceptually important therapeutic target is to improve cardiac output in order to alleviate signs of hypoperfusion. Accordingly, the majority of these patients will require an inotrope as cardiac dysfunction is the cause of their low cardiac output. However, the short-term use of currently available inotropes has been associated with further decreases in blood pressure and increases in heart rate, myocardial oxygen consumption and arrhythmias. Agents that improve cardiac contractility without this undesirable effects should be developed. To the best of our knowledge, the epidemiology, pathophysiology and therapy of patients with HF-LBP have not been addressed thoroughly. In June 2010, a workshop that included scientists and clinicians was held in Rome, Italy. The objectives of this meeting were to (1) develop a working definition for HF-LBP, (2) describe its clinical characteristics and pathophysiology, (3) review current therapies and their limitations, (4) discuss novel agents in development and (5) create a framework for the design and conduct of future clinical trials.

Relationship between systolic blood pressure and preserved or reduced ejection fraction at admission in patients hospitalized for acute heart failure syndromes

BACKGROUND

Among patients with acute heart failure syndromes (AHFS), it has been reported that those with a reduced left ventricular ejection fraction (LVEF) tend to be hypotensive or normotensive, whereas those with a preserved LVEF tend to be hypertensive. However, it is unclear whether the systolic blood pressure (SBP) is actually associated with the LVEF in AHFS patients. Therefore, we evaluated the relationship between the SBP at admission and LVEF in patients hospitalized for AHFS.

METHODS

Data from the Acute Decompensated Heart Failure Syndromes (ATTEND) registry were analyzed to investigate the relationship between the admission SBP and a preserved or reduced LEF in AHFS patients. Of the 4,842 patients enrolled in this registry, 4,831 patients (99.8%) were evaluated. They were divided into SBP quartiles (SBP <120, 120 to <140, 140 to <160, and ≥160 mmHg), and LVEF was compared among the quartiles.

RESULTS

Patients with an admission SBP <120 mmHg were more likely to have a reduced LVEF than a preserved LVEF. In contrast, patients with an admission SBP ≥120 mmHg were equally likely to have a preserved or reduced LVEF, indicating that there was no relation between a higher admission SBP and the LVEF.

CONCLUSIONS

Our data indicated that an elevated SBP at admission may not be useful to distinguish between a preserved or reduced LVEF in the urgent phase of AHFS. However, taking geographical differences of AHFS into consideration, further investigations are needed to clarify the relationship between admission SBP and LVEF in patients hospitalized for AHFS.

Micro-arrayed human embryonic stem cells-derived cardiomyocytes for in vitro functional assay

Introduction

The heart is one of the least regenerative organs in the body and any major insult can result in a significant loss of heart cells. The development of an in vitro-based cardiac tissue could be of paramount importance for many aspects of the cardiology research. In this context, we developed an in vitro assay based on human cardiomyocytes (hCMs) and ad hoc micro-technologies, suitable for several applications: from pharmacological analysis to physio-phatological studies on transplantable hCMs. We focused on the development of an assay able to analyze not only hCMs viability, but also their functionality.

Methods

hCMs were cultured onto a poly-acrylamide hydrogel with tunable tissue-like mechanical properties and organized through micropatterning in a 20×20 array. Arrayed hCMs were characterized by immunofluorescence, GAP-FRAP analyses and live and dead assay. Their functionality was evaluated monitoring the excitation-contraction coupling.

Results

Micropatterned hCMs maintained the expression of the major cardiac markers (cTnT, cTnI, Cx43, Nkx2.5, α-actinin) and functional properties. The spontaneous contraction frequency was (0.83±0.2) Hz, while exogenous electrical stimulation lead to an increase up to 2 Hz. As proof of concept that our device can be used for screening the effects of pathological conditions, hCMs were exposed to increasing levels of H₂O₂. Remarkably, hCMs viability was not compromised with exposure to 0.1 mM H₂O₂, but hCMs contractility was dramatically suppressed. As proof of concept, we also developed a microfluidic platform to selectively treat areas of the cell array, in the perspective of performing multi-parametric assay.

Conclusions

Such system could be a useful tool for testing the effects of multiple conditions on an in vitro cell model representative of human heart physiology, thus potentially helping the processes of therapy and drug development.

PDE5 Inhibitors as Potential Tools in the Treatment of Cystic Fibrosis

Despite great advances in the understanding of the genetics and pathophysiology of cystic fibrosis (CF), there is still no cure for the disease. Using phosphodiesterase type 5 (PDE5) inhibitors, we and others have provided evidence of rescued F508del-CFTR trafficking and corrected deficient chloride transport activity. Studies using PDE5 inhibitors in mice homozygous for the clinically relevant F508del mutation have been conducted with the aim of restoring F508del-CFTR protein function. We demonstrated, by measuring transepithelial nasal potential difference in F508del mice following intraperitoneal injection of sildenafil, vardenafil, or taladafil at clinical doses are able to restore the decreased CFTR-dependent chloride transport across the nasal mucosa. Moreover, vardenafil, but not sildenafil, stimulates chloride transport through the normal CFTR protein. We developed a specific nebulizer setup for mice, with which we demonstrated, through a single inhalation of PDE5 inhibitors, local activation of CFTR protein in CF. Significant potential advantages of inhalation drug therapy over oral or intravenous routes include rapid onset of pharmacological action, reduced systemic secondary effects, and reduced effective drug doses compared to the drug delivered orally; this underlines the relevance and impact of our work for translational science. More recently, we analyzed the bronchoalveolar lavage of CF and wild-type mice for cell infiltrates and expression of pro-inflammatory cytokines and chemokines; we found that the CFTR activating effect of vardenafil, selected as a representative long-lasting PDE5 inhibitor, breaks the vicious circle of lung inflammation which plays a major role in morbi-mortality in CF. Our data highlight the potential use of PDE5 inhibitors in CF. Therapeutic approaches using clinically approved PDE5 inhibitors to address F508del-CFTR defects could speed up the development of new therapies for CF.

Cardiac AAV9-S100A1 gene therapy rescues post-ischemic heart failure in a preclinical large animal model

As a prerequisite for clinical application, we determined the long-term therapeutic effectiveness and safety of adeno-associated virus (AAV)-S100A1 gene therapy in a preclinical large animal model of heart failure. S100A1, a positive inotropic regulator of myocardial contractility, becomes depleted in failing cardiomyocytes in humans and animals, and myocardial-targeted S100A1 gene transfer rescues cardiac contractile function by restoring sarcoplasmic reticulum calcium (Ca(2+)) handling in acutely and chronically failing hearts in small animal models. We induced heart failure in domestic pigs by balloon occlusion of the left circumflex coronary artery, resulting in myocardial infarction. After 2 weeks, when the pigs displayed significant left ventricular contractile dysfunction, we administered, by retrograde coronary venous delivery, AAV serotype 9 (AAV9)-S100A1 to the left ventricular, non-infarcted myocardium. AAV9-luciferase and saline treatment served as control. At 14 weeks, both control groups showed significantly decreased myocardial S100A1 protein expression along with progressive deterioration of cardiac performance and left ventricular remodeling. AAV9-S100A1 treatment prevented and reversed these functional and structural changes by restoring cardiac S100A1 protein levels. S100A1 treatment normalized cardiomyocyte Ca(2+) cycling, sarcoplasmic reticulum calcium handling, and energy homeostasis. Transgene expression was restricted to cardiac tissue, and extracardiac organ function was uncompromised. This translational study shows the preclinical feasibility of long-term therapeutic effectiveness of and a favorable safety profile for cardiac AAV9-S100A1 gene therapy in a preclinical model of heart failure. Our results present a strong rationale for a clinical trial of S100A1 gene therapy for human heart failure that could potentially complement current strategies to treat end-stage heart failure.

Chronic istaroxime improves cardiac function and heart rate variability in cardiomyopathic hamsters

PURPOSE

Istaroxime is a new luso-inotropic compound. It exerts inotropic action by reducing Na+/K+-ATPase activity, and simultaneously it stimulates sarcoplasmic reticulum Ca(2+)-ATPase function, thus also inducing lusitropic action. The aim of present study is to assess the effect of chronic istaroxime treatment on cardiac function and heart rate variability in Bio TO.2 Syrian hamster model of progressive heart failure.

METHODS

Bio TO.2 hamsters were daily treated, from 12 to 28 weeks of age, with 30 mg/kg/day oral istaroxime. Age-matched Bio TO.2 and Bio F1B hamsters were treated with vehicle and used as diseased and healthy controls. At the end of treatment, hearts function and autonomic cardiac control were evaluated.

RESULTS

Hearts from vehicle-treated Bio TO.2 when compared with hearts from Bio F1B showed higher heart/body weight ratio, and lower left ventricular systolic pressure (LVSP), positive and negative derivative of LV pressure (dP/dT), coronary flow rate (CFR). Hearts from istaroxime-treated when compared with those of vehicle-treated hamsters, showed the reduction of heart/body weight ratio, and the increase of LVSP, of both positive and negative dP/dT, and of CFR. Autonomic cardiac control, evaluated by HRV analysis, indicated in vehicle-treated Bio TO.2 hamsters, when compared to healthy, a shift towards increased sympathetic and decreased parasympathetic activities. Istaroxime-treatment preserved parasympathetic activity.

CONCLUSIONS

Chronic istaroxime improves cardiac function and heart rate variability in Bio TO.2 Syrian hamster model of progressive heart failure.

Positive inotropes in heart failure: a review article

Increasing myocardial contractility has long been considered a big help for patients with systolic heart failure, conferring an augmented haemodynamic profile in terms of higher cardiac output, lower cardiac filling pressure and better organ perfusion. Though concerns have been raised over the safety issues regarding the clinical trials of different inotropes in hearts with systolic dysfunction, they still stand as a main therapeutic strategy in many centres dealing with such patients. They must be used as short in duration, low in dose and stopped as early as possible. Evidence-based guidelines have provided clinicians with valuable data for better applying inotropes in heart failure patients. In this paper, the authors address clinical trials with different agents used for increasing cardiac contractility in heart failure patients. Furthermore, the authors focus on recent guidelines on making the most out of inotropes in heart failure patients.

Hyponatremia and congestive heart failure: a marker of increased mortality and a target for therapy

Heart failure is one of the most common chronic medical conditions in the developed world. It is characterized by neurohormonal activation of multiple systems that can lead to clinical deterioration and significant morbidity and mortality. In this regard, hyponatremia is due to inappropriate and continued vasopressin activity despite hypoosmolality and volume overload. Hyponatremia is also due to diuretic use in an attempt to manage volume overload. When hyponatremia occurs, it is a marker of heart failure severity and identifies patients with increased mortality. The recent introduction of specific vasopressin-receptor antagonists offers a targeted pharmacological approach to these pathophysiological derangements. Thus far, clinical trials with vasopressin-receptor antagonists have demonstrated an increase in free-water excretion, improvement in serum sodium, modest improvements in dyspnea but no improvement in mortality. Continued clinical trials with these agents are needed to determine their specific role in the treatment of both chronic and decompensated heart failure.

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.

Inotropes in cardiac patients: update 2011

PURPOSE OF REVIEW

ICU patients frequently develop low output syndromes due to cardiac dysfunction, myocardial injury, and inflammatory activation. Conventional inotropic agents seem to be useful in restoring hemodynamic parameters and improving peripheral organ perfusion, but can increase short-term and long-term mortality in these patients. Novel inotropes may be promising in the management of ICU patients, having no serious adverse effects. This review summarizes all the current knowledge about the use of conventional and new inotropic agents in various clinical entities of critically ill patients.

RECENT FINDINGS

In recent European Society of Cardiology guidelines, inotropic agents are administered in patients with low output syndrome due to impaired cardiac contractility, and signs and symptoms of congestion. The most recommended inotropes in this condition are levosimendan and dobutamine (both class of recommendation: IIa, level of evidence: B). Recent data indicate that levosimendan may be useful in postmyocardial infarction cardiac dysfunction and septic shock through increasing coronary flow and attenuating inflammatory activation, respectively. Furthermore, calcium sensitizing by levosimendan can be effectively used for weaning of mechanical ventilation in postcardiac surgery patients and has also cardioprotective effect as expressed by the absence of troponin release in this patient population. Finally, new agents, such as istaroxime and cardiac myosin activators may be safe and improve central hemodynamics in experimental models of heart failure and heart failure patients in phase II clinical trials; however, large-scale randomized clinical trials are required.

SUMMARY

In an acute cardiac care setting, short-term use of inotropic agents is crucial for the restoration of arterial blood pressure and peripheral tissue perfusion, as well as weaning of cardiosurgery. New promising agents should be tested in randomized clinical trials.

Baroreflex sensitivity might predict responders to milrinone in patients with heart failure

The phosphodiesterase III inhibitor milrinone (MIL) is considered to be effective for "wet and cold" heart failure. In some cases, however, the inotropic effects of milrinone are insufficient. A previous study suggested that baroreflex sensitivity (BRS) predicts the cases in which MIL increases left ventricular dp/dt. The aim of this study was to determine whether BRS measured using the spontaneous sequence method predicts the MIL responders. Twenty-four patients with "wet and cold" heart failure whose systolic blood pressure > 100 mmHg were enrolled. At 2 hours MIL improved dys-pnea, general fatigue, urine volume, and tricuspid regurgitant pressure gradient in 13 patients (responders; R group), whereas it failed to improve in 11 patients (nonresponders; NR group). BRS in the R group was significantly higher than that in the NR group prior to the MIL infusion. At 2 hours after the MIL infusion, BRS was further increased in the R group, but did not increase in the NR group. The sensitivity and specificity of BRS at a cut-off level of 5 ms/mmHg for the prediction of R group were 0.94 and 0.93, respectively. BRS might be useful for identifying potential responders to milrinone in patients with blood pressure-preserved "wet and cold" heart failure.

Diuretic therapy in heart failure: current controversies and new approaches for fluid removal

Hospitalization for heart failure is a major health problem with high in-hospital and postdischarge mortality and morbidity. Non-potassium-sparing diuretics (NPSDs) still remain the cornerstone of therapy for fluid management in heart failure despite the lack of large randomized trials evaluating their safety and optimal dosing regimens in both the acute and chronic setting. Recent retrospective data suggest increased mortality and re-hospitalization rates in a wide spectrum of heart failure patients receiving NPSDs, particularly at high doses. Electrolyte abnormalities, hypotension, activation of neurohormones, and worsening renal function may all be responsible for the observed poor outcomes. Although NPSD will continue to be important agents to promptly resolve signs and symptoms of heart failure, alternative therapies such as vasopressine antagonists and adenosine blocking agents or techniques like veno-venous ultrafiltration have been developed in an effort to reduce NPSD exposure and minimize their side effects. Until other new agents become available, it is probably prudent to combine NPSD with aldosterone blocking agents that are known to improve outcomes.

Acute pulmonary oedema: clinical characteristics, prognostic factors, and in-hospital management

AIMS

Acute pulmonary oedema (APE) is the second, after acutely decompensated chronic heart failure (ADHF), most frequent form of acute heart failure (AHF). This subanalysis examines the clinical profile, prognostic factors, and management of APE patients (n = 1820, 36.7%) included in the Acute Heart Failure Global Survey of Standard Treatment (ALARM-HF).

METHODS AND RESULTS

ALARM-HF included a total of 4953 patients hospitalized for AHF in Europe, Latin America, and Australia. The final diagnosis was made at discharge, and patients were classified according to European Society of Cardiology guidelines. Patients with APE had higher in-hospital mortality (7.4 vs. 6.0%, P = 0.057) compared with ADHF patients (n = 1911, 38.5%), and APE patients exhibited higher systolic blood pressures (P < 0.001) at admission and higher left ventricular ejection fraction (LVEF, P < 0.01) than those with ADHF. These patients also had a higher prevalence of diabetes (P < 0.01), arterial hypertension (P < 0.001), peripheral vascular disease (P < 0.001), and chronic renal disease (P < 0.05). They were also more likely to receive intravenous (i.v.) diuretics (P < 0.001), i.v. nitrates (P < 0.01), dopamine (P < 0.05), and non-invasive ventilation (P < 0.001). Low systolic blood pressure (P < 0.001), low LVEF (<0.05), serum creatinine ≥1.4 mg/dL (P < 0.001), history of cardiomyopathy (P < 0.05), and previous cardiovascular event (P < 0.001) were independently associated with increased in-hospital mortality in the APE population.

CONCLUSION

APE differs in clinical profile, in-hospital management, and mortality compared with ADHF. Admission characteristics (systolic blood pressure and LVEF), renal function, and history may identify high-risk APE patients.

Update on inotropic therapy in the management of acute heart failure

The use of classic inotropic agents activating the beta-receptor-cyclic adenosine monophosphate (cAMP) pathway (ie, dobutamine or milrinone) should be restricted to a "rescue" therapy in patients with acute heart failure and signs of peripheral hypoperfusion (hypotension, renal dysfunction) that is refractory to volume replacement, diuretics, and vasodilators. This approach is largely supported by observations from clinical trials suggesting that both short-term treatment of acute heart failure without an essential requirement of inotropic support as well as long-term inotropic therapy in patients with severe chronic heart failure with classical inotropic agents can increase arrhythmia and mortality. Vice versa, beta-receptor blockade, whenever tolerated, improves survival in patients with severe stable heart failure, further supporting the concept that beta-receptor stimulation has adverse long-term effects. Positive inotropic therapy stimulating the beta-receptor-cAMP pathway should, therefore, be used with caution, given the potential harmful effects. Levosimendan, a novel calcium sensitizer, has recently attracted substantial clinical interest and may be superior to classical inotropes with respect to improving cardiac mechanical efficiency and avoiding adverse effects such as increasing myocardial oxygen uptake or cardiomyocyte death. Earlier clinical studies have suggested a beneficial effect on survival compared with dobutamine or placebo in patients with acute heart failure (LIDO , RUSSLAN , and CASINO trials). However, more recent data from two large clinical trials (SURVIVE and REVIVE trials) did not confirm these beneficial effects on mortality. Therefore, additional data are required with respect to the optimum dosing of levosimendan and patient selection to reach a definitive conclusion about the role of levosimendan in the management of patients with acute heart failure.

Weaning difficult-to-wean chronic obstructive pulmonary disease patients: a pilot study comparing initial hemodynamic effects of levosimendan and dobutamine

PURPOSE

To compare the short-term hemodynamic effects of levosimendan and dobutamine in chronic obstructive pulmonary disease (COPD) patients experiencing weaning difficulties in relation with increased left ventricular filling pressure.

MATERIALS AND METHODS

This prospective, sequential, pilot study included 10 COPD patients experiencing weaning difficulties in relation with increased left ventricular filling pressure ascertained by an increase >10 mm Hg of pulmonary artery occlusion pressure (PAOP) at the shift from mechanical to spontaneous breathing (SB). Patients received 1 h infusion of 7 μg/kg per minute of dobutamine, followed by 24-hour infusion of 0.2 μg/kg per minute levosimendan. Hemodynamic variables were measured under MV and 15 to 30 minutes after SB at baseline, at the end of dobutamine infusion, at a washout period, and after levosimendan infusion.

RESULTS

At baseline, the shift from mechanical ventilation to spontaneous ventilation was associated with a significant increase in PAOP from a median of 15 (interquartile range [IQR], 6) to 29 (9) mm Hg. Both drugs reduced significantly the level of PAOP increase at SB, but levosimendan had a greater effect than dobutamine [median PAOP increase (IQR): 5 (2) vs 9 (4) mm Hg, respectively; P < .01].

CONCLUSIONS

Both drugs reduced the magnitude of PAOP increase at SB in difficult-to-wean COPD patients. PAOP increase was reduced to a greater extent by levosimendan.

Cardiovascular Effects in Rats following Exposure to a Receptor Tyrosine Kinase Inhibitor

The receptor tyrosine kinase receptor (RTK) signaling pathway, mesenchymal-epithelial transition factor (c-Met)/hepatocyte growth factor receptor (HGFR), has been implicated in oncogenesis and is a target of interest in cancer therapy. PF-04254644 is a potent and selective inhibitor of c-Met/HGFR. Wide ligand binding profiling of PF-04254644 revealed a potentially significant interaction with phosphodiesterase (PDE) 3, and follow-up PDE enzyme activity assays confirmed PF-04254644 as a potent inhibitor of PDE3 as well as other PDEs (1, 2, 5, 10, and 11). Clinical observations, laboratory, and echocardiography parameters were recorded in Sprague-Dawley (SD) rats that received PF-04254644 oral dosing for up to seven consecutive days. Toxicological evaluations revealed myocardial degeneration as an adverse event at all tested doses. Echocardiographic evaluations revealed an increase in heart rate (HR) and contractility after the first dose with PF-04254644 and myocardial fibrosis correlated with decreased cardiac function after repeat dosing. A study in telemetry-instrumented rats substantiated that PF-04254644 induced a sustained increased HR and decreased contractility after six days of treatment. Data suggest that the decreased cardiac function and cardiotoxicity are likely due to inhibition of multiple PDEs by PF-04254644.

Compartmentalized cyclic adenosine 3',5'-monophosphate at the plasma membrane clusters PDE3A and cystic fibrosis transmembrane conductance regulator into microdomains

Formation of multiple-protein macromolecular complexes at specialized subcellular microdomains increases the specificity and efficiency of signaling in cells. In this study, we demonstrate that phosphodiesterase type 3A (PDE3A) physically and functionally interacts with cystic fibrosis transmembrane conductance regulator (CFTR) channel. PDE3A inhibition generates compartmentalized cyclic adenosine 3',5'-monophosphate (cAMP), which further clusters PDE3A and CFTR into microdomains at the plasma membrane and potentiates CFTR channel function. Actin skeleton disruption reduces PDE3A-CFTR interaction and segregates PDE3A from its interacting partners, thus compromising the integrity of the CFTR-PDE3A-containing macromolecular complex. Consequently, compartmentalized cAMP signaling is lost. PDE3A inhibition no longer activates CFTR channel function in a compartmentalized manner. The physiological relevance of PDE3A-CFTR interaction was investigated using pig trachea submucosal gland secretion model. Our data show that PDE3A inhibition augments CFTR-dependent submucosal gland secretion and actin skeleton disruption decreases secretion.

Hyponatremia in heart failure: the role of arginine vasopressin and diuretics

PURPOSE

To provide an overview of the role of arginine vasopressin (AVP) in the development of hyponatremia in patients with heart failure (HF), the role of diuretics, and the potential for vasopressin-receptor antagonists in the treatment of HF.

METHODS

A MEDLINE literature search was performed to identify articles relating to HF, diuretics, hyponatremia, AVP, and vasopressin-receptor antagonists.

DISCUSSION

HF affects more than 5 million patients in the United States and is associated with substantial cost, morbidity, and mortality. One of the complications associated with HF, as well as with its treatment, is the development of hyponatremia. Hyponatremia in patients with HF is associated with poor outcomes and can limit the use of diuretic therapy. AVP is the primary stimulus to the development of hyponatremia in these patients and therapies that target AVP action would seem a logical choice in the therapeutic regimen for HF. Drugs that antagonize the vasopressin V(2) receptor, which is primarily responsible for water resorption in the kidney, are now available and have been studied in patients with HF. These drugs have been associated with improvements in serum sodium concentration, urine output, and body weight, but have shown no long-term mortality benefit in patients with HF. In a subset of patients with baseline hyponatremia, these agents improved quality of life scores.

CONCLUSION

Vasopressin-receptor antagonists may prove useful in the treatment of HF; however, the exact role of these agents in the treatment of HF still requires further study.

Specific mediator inhibition by the NO donors SNP and NCX 2057 in the peripheral lung: implications for allergen-induced bronchoconstriction

Background

The aim of this study was to examine potential therapeutic effect of the two NO donors NCX 2057 (3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid) 4-(nitrooxy)butyl ester) and SNP (sodium nitroprusside) on the early allergic airway response in the peripheral lung.

Methods

The experiments were performed in guinea pig lung parenchyma (GPLP) derived from ovalbumin (OVA) sensitized guinea pigs. The effects of NCX 2057 and SNP were evaluated by contractile responses and mediator release during OVA challenge. The generation of nitrite and nitrate was assessed by chemiluminescence. Statistical analysis was evaluated by ANOVA.

Results

Cumulatively increasing concentrations of OVA (1–10,000 ng/ml) induced concentration-dependent contractions of the GPLP that were reduced by NCX 2057 (100 μM, p < 0.001) and SNP (100 μM, p < 0.05). Antigen-induced eicosanoid release was decreased by NCX 2057 (100 μM, p < 0.001) but not by SNP (100 μM), whereas the release of histamine was reduced by SNP (100 μM, p < 0.001) but not by NCX 2057 (100 μM). In addition, NCX 2057 (0.1–100 μM), but not SNP (0.1–100 μM), relaxed leukotriene D₄ (10 nM) precontracted GPLP (p < 0.01). The guanylyl cyclase inhibitor ODQ had no effect on the NCX 2057 mediated relaxation. SNP released significantly less nitrite than NCX 2057.

Conclusion

Although both SNP and NCX 2057 reduced the release of pro-inflammatory mediators, their profiles were distinctly different. Furthermore, NCX 2057 also induced smooth muscle dilation in the GPLP. The findings point to specific anti-inflammatory effects of different NO donors in the peripheral lung tissue.

Pivotal effects of phosphodiesterase inhibitors on myocyte contractility and viability in normal and ischemic hearts

Phosphodiesterases (PDEs) are enzymes that degrade cellular cAMP and cGMP and are thus essential for regulating the cyclic nucleotides. At least 11 families of PDEs have been identified, each with a distinctive structure, activity, expression, and tissue distribution. The PDE type-3, -4, and -5 (PDE3, PDE4, PDE5) are localized to specific regions of the cardiomyocyte, such as the sarcoplasmic reticulum and Z-disc, where they are likely to influence cAMP/cGMP signaling to the end effectors of contractility. Several PDE inhibitors exhibit remarkable hemodynamic and inotropic properties that may be valuable to clinical practice. In particular, PDE3 inhibitors have potent cardiotonic effects that can be used for short-term inotropic support, especially in situations where adrenergic stimulation is insufficient. Most relevant to this review, PDE inhibitors have also been found to have cytoprotective effects in the heart. For example, PDE3 inhibitors have been shown to be cardioprotective when given before ischemic attack, whereas PDE5 inhibitors, which include three widely used erectile dysfunction drugs (sildenafil, vardenafil and tadalafil), can induce remarkable cardioprotection when administered either prior to ischemia or upon reperfusion. This article provides an overview of the current laboratory and clinical evidence, as well as the cellular mechanisms by which the inhibitors of PDE3, PDE4 and PDE5 exert their beneficial effects on normal and ischemic hearts. It seems that PDE inhibitors hold great promise as clinically applicable agents that can improve cardiac performance and cell survival under critical situations, such as ischemic heart attack, cardiopulmonary bypass surgery, and heart failure.

Overview of emerging pharmacologic agents for acute heart failure syndromes

BACKGROUND

Several therapies commonly used for the treatment of acute heart failure syndromes (AHFS) present some well-known limitations and have been associated with an early increase in the risk of death. There is, therefore, an unmet need for new pharmacologic agents for the early management of AHFS that may improve both short- and long-term outcomes.

AIM

To review the recent evidence on emerging pharmacologic therapies in AHFS.

METHODS

A systematic search of peer-reviewed publications was performed on MEDLINE, EMBASE and Clinical Trials.gov from January 1990 to August 2007. The results of unpublished or ongoing trials were obtained from presentations at national and international meetings and pharmaceutical industry releases. Bibliographies from these references were also reviewed, as were additional articles identified by content experts.

RESULTS

Cumulative data from large studies and randomised trials suggest that therapies with innovative mechanisms of action may safely and effectively reduce pulmonary congestion or improve cardiac performance in AHFS patients.

CONCLUSION

Some investigational agents for the management of AHFS are able to improve haemodynamics and/or clinical status. In spite of these promising findings, no new agent has demonstrated a clear benefit in terms of long-term clinical outcomes compared to placebo or conventional therapies.

New pharmacologic therapies for acute heart failure

Given the limitations of high-dose diuretics and vasodilators and the increasing literature showing that inotropes, regardless of the dose used, have a detrimental effect on mortality, a variety of new agents are under investigation for the treatment of pulmonary and systemic congestion and restoration of cardiac output in the setting of acute heart failure syndromes. The new therapeutic approach is based on two goals: short-term improvement in symptoms together with long-term improvement of cardiac function. This review describes new agents that are in preclinical and in clinical phases with realistic prospects: anti-endothelin, natriuretic peptides, istaroxime, levosimendan, myosin activators, and vasopressin antagonists. Those new therapeutic strategies aim to act at the cellular level to improve vessel and heart functions, with minimal side effects, together with improved sodium and water balance.