Effects of low-dose oral enoximone administration on mortality, morbidity, and exercise capacity in patients with advanced heart failure: the randomized, double-blind, placebo-controlled, parallel group ESSENTIAL trials

Perioperative administration of enoximone and renal function after cardiac surgery: a propensity-matched analysis

BACKGROUND

Perioperative administration of enoximone has been shown to improve hemodynamics, organ function, and inflammatory response. Aim of the present study is to evaluate the impact of enoximone on postoperative renal function after on-pump cardiac surgery.

METHODS

A total of 3727 patients undergoing cardiac surgery at one Institution between May 2004 and November 2010 were reviewed. A propensity score was built and a 1:1 perfect matching was performed, providing two fairly comparable cohorts of 712 patients each, receiving or not enoximone after surgery. Renal function was evaluated by lower glomerular filtration rate (GFR) value reached postoperatively.

RESULTS

Overall 30-day mortality rate was 4.3% (62/1424). Cumulative incidence of postoperative renal failure (RF) was 157/1424(11%), of which 99/1424(7%) needed renal replacement therapy. Mean lower postoperative GFR in patients who received or not enoximone was 63 ± 30.1 and 53.5 ± 26.1 ml/min/1.73 m(2) (p<0.0001), respectively. At multivariable analysis age (OR2.75, p=0.0004), diabetes (OR1.82, p=0.006), preoperative GFR (OR3.81, p<0.0001), preoperative cardiogenic shock (OR1.65, p=0.004), previous cardiac surgery (OR2.12, p=0.0002), type of intervention (OR1.96, p=0.005), and enoximone (OR0.38, p=0.001) were found to be independently associated with postoperative RF. Logistic regression analysis showed that the administration of enoximone (OR0.41, p=0.0001), and of no inotropes (OR0.27, p<0.0001) were protective vs. the occurrence of postoperative RF.

CONCLUSION

Patients perioperatively receiving enoximone showed a statistically significant better renal function after cardiac surgery.

A review of current therapies used in the treatment of congestive heart failure

Congestive heart failure is the leading cause of hospitalizations for patients older than 65 years. There are almost 700,000 new cases of heart failure annually and re-hospitalization rates are as high as 50% within the first few months of initial discharge. These statistics translate to healthcare costs that nearly reached US$40 billion in 2010. Understanding the therapeutic agents that can not only help decrease mortality and morbidity but also decrease the rate of re-hospitalizations is vital in the management of congestive heart failure. Here, the authors highlight the various classes of drugs used in the treatment of heart failure. They then provide a focused review examining the multiple clinical trials that have emphasized the evaluation of mortality, morbidity and hospitalization rates in heart failure patients who are receiving the different types of therapeutic agents.

Inotropes for the management of acute heart failure patients with renal dysfunction. Still an option?

INTRODUCTION

Renal dysfunction is highly prevalent in patients with acute heart failure (AHF). These patients are more vulnerable in worsening of kidney function and have also higher mortality rates.

AREAS COVERED

Recent developments in the understanding of bidirectional interaction between heart and kidney are reviewed in the context of the potential impact of inotropes on renal function. Key clinical trials reporting the use of inotropes in AHF patients with renal dysfunction are discussed in this review.

EXPERT OPINION

Inotropes may be indicated on a short-term basis and under close monitoring in AHF with renal dysfunction mostly in cases of low output heart failure that can provoke renal hypoperfusion. Dopamine administration with low dose of i.v. furosemide has been recently compared with high dose of i.v. furosemide alone, demonstrating lower rates of worsening renal function and electrolyte disturbances. Moreover, small clinical trials have shown that the novel inodilator levosimendan seems to be superior to dobutamine or placebo in improving renal function in patients with acutely decompensated heart failure. The impact of novel inotropes on kidney function is still unclear. Randomized clinical trials are required in order to identify the role of inotropes in the management and/or prevention of acute cardiorenal syndrome.

Rationale and study design of the increase of vagal tone in heart failure study: INOVATE-HF

BACKGROUND

Imbalance between the parasympathetic and sympathetic nervous systems is a recognized contributor to progression of chronic heart failure. Current therapy with beta adrenergic antagonists is designed to moderate the up-regulation of norepinephrine and sympathetic effects; however, to date, there are no therapies that specifically address the withdrawal of parasympathetic influences on cardiac function and structure.

METHODS/RESULTS

In order to evaluate the impact of vagus nerve stimulation, an international multi-center randomized clinical trial (INOVATE-HF) has been designed to assess safety and efficacy of vagus nerve stimulation in symptomatic patients with heart failure on optimal medical therapy using the CardioFit System (BioControl Medical, Yehud, Israel). Up to 650 patients from 80 sites will be recruited and randomized in a 3:2 ratio to receive active treatment or standard optimal medical therapy. Inclusion criteria include left ventricular systolic dysfunction, the presence of New York Heart Association Class III symptoms, sinus rhythm, and QRS width less than 120 milliseconds. The study is powered to detect differences in the primary efficacy end point of all-cause mortality and heart failure hospitalization and 2 safety end points.

CONCLUSION

Vagal nerve stimulation with CardioFit as a treatment for symptomatic heart failure is under active investigation as a novel approach to restore balance between the sympathetic and parasympathetic nervous systems. If shown to be safe and effective in decreasing heart failure events and mortality, this novel approach will impact the treatment paradigm for heart failure.

Biomarkers as surrogate end points in heart failure trials

Despite the continued growth of heart failure as a major public health problem, the development of new therapies for heart failure has slowed and recent studies have been neutral, suggesting the need for a reappraisal of the clinical research enterprise. Surrogate end points, defined as measurements that are used as substitutes for the more clinically meaningful end points, can play a valuable role in clinical trials by accelerating the timeline for determining appropriate dosages, efficacy, and safety. Biomarkers, such as the natriuretic peptides, have many of the characteristics of valid surrogates but have not been sufficiently validated for widespread use. Ongoing research into the role of biomarkers as surrogates may lead to better clinical trial design and more efficient development of new therapies for heart failure.

Imaging surrogate end points in heart failure trials

Despite the epidemiologic importance, large investments, and careful design, recent results of heart failure (HF) trials have been unable to demonstrate significant treatment improvements. This shortcoming has led to a reassessment of research methodology, particularly related to sample size and costs, for which end-point selection is a main issue. In comparing interventions in clinical trials, surrogate end points may be used to reduce the costs. To this end, ongoing research into the roles of imaging biomarkers as reliable surrogate end points may lead to better clinical trial design and more efficient development of new therapies for HF.

Treatment of chronic heart failure with β-adrenergic receptor antagonists: a convergence of receptor pharmacology and clinical cardiology

Despite the absence of a systematic development plan, β-blockers have reached the top tier of medical therapies for chronic heart failure. The successful outcome was due to the many dedicated investigators who produced, over a 30-year period, increasing evidence that β-blocking agents should or actually did improve the natural history of dilated cardiomyopathies and heart failure. It took 20 years for supportive evidence to become undeniable, at which time in 1993 the formidable drug development resources of large pharmaceutical companies were deployed into Phase 3 trials. Success then came relatively quickly, and within 8 years multiple agents were on the market in the United States and Europe. Importantly, there is ample room to improve antiadrenergic therapy, through novel approaches exploiting the nuances of receptor biology and/or intracellular signaling, as well as through pharmacogenetic targeting.

Old and new intravenous inotropic agents in the treatment of advanced heart failure

Inotropic agents are administered to improve cardiac output and peripheral perfusion in patients with systolic dysfunction and low cardiac output. However, there is evidence of increased mortality and adverse effects associated with current inotropic agents. These adverse outcomes may be ascribed to patient selection, increased myocardial energy expenditure and oxygen consumption, or to specific mechanisms of action. Both sympathomimetic amines and type III phosphodiesterase inhibitors act through an increase in intracellular cyclic adenosine monophoshate and free calcium concentrations, mechanisms that increase oxygen consumption and favor arrhythmias. Concomitant peripheral vasodilation with some agents (phosphodiesterase inhibitors and levosimendan) may also lower coronary perfusion pressure and favor myocardial damage. New agents with different mechanisms of action might have a better benefit to risk ratio and allow an improvement in tissue and end-organ perfusion with less untoward effects. We have summarized the characteristics of the main inotropic agents for heart failure treatment, the data from randomized controlled trials, and future perspectives for this class of drugs.

Chronic heart failure: current evidence, challenges to therapy, and future directions

Heart failure (HF) is a complex syndrome characterized by the inability of the heart to maintain a normal cardiac output without elevated intracardiac filling pressures, resulting in signs of pulmonary and peripheral edema and symptoms of dyspnea and fatigue. Central to the management of HF is a multifaceted pharmacological intervention to abate the harmful counter-regulatory effects of neurohormonal activation and avid salt and water retention. Whereas up to 40 years ago HF was managed with diuretics and leaf of digitalis, the cornerstones of therapy for HF patients with systolic dysfunction now include ACE inhibitors or angiotensin II type 1 receptor antagonists (angiotensin receptor blockers), β-adrenoceptor antagonists (β-blockers), and aldosterone antagonists, which have significantly improved survival. However, with the increasing number of beneficial therapies, there are challenges to implementing all of them. Specific cardiomyopathies also merit specific considerations with respect to treatment, and - unfortunately - there is no therapy for HF with preserved left ventricular ejection fraction that has been shown to improve survival. Although mortality has improved in HF, the biggest challenge to treatment lies in addressing the morbidity of this disease, which is now the most common reason for hospital admission in our aged population. As such, there are many therapies that may serve to improve the quality of life of HF patients. Future HF treatment regimens may include direct cellular therapy via hormone and cytokine signaling or cardiac regeneration through growth factors or cell therapy.

Medical therapy for chronic heart failure

Understanding of contemporary pharmacological therapy for chronic heart failure continues to evolve. In this Review, we discuss how findings from clinical trials have caused the roles of old therapies to be expanded and past treatment algorithms to be challenged. Several trials investigating preserved ejection fraction as a measure of heart failure had disappointing results, although important studies are in progress. Many novel therapeutic approaches for heart failure have emerged and are discussed in this review. The pharmacological treatments for heart failure continue to change, with many exciting possibilities for the future.

Inotropic therapy for end-stage heart failure patients

OPINION STATEMENT

Positive inotropic agents play an important role in the management of acute decompensated heart failure (HF) patients with reduced cardiac output and poor end-organ perfusion. However, despite their acute hemodynamic benefits, the role of inotropes in the management of chronic advanced HF remains limited. Although digoxin has demonstrated the ability to improve symptoms in HF patients, numerous small, mostly nonrandomized studies have shown that patients with advanced HF improve symptomatically when administered continuous or intermittent intravenous β-agonists or phosphodiesterase inhibitors. However, this improvement occurs at the expense of an increased risk of cardiac arrhythmias, sudden cardiac death, and mortality. Similarly, several oral inotropes have been developed and studied in larger randomized clinical trials. The PROMISE study found that oral milrinone is associated with increased mortality, whereas the ESSENTIAL study showed that oral enoximone does not result in any significant improvement in symptoms, exercise capacity, or survival. The calcium-sensitizing inotrope levosimendan has shown some promise in the management of acute HF patients, but the PERSIST trial showed no improvement in survival or hospitalization rates with chronic oral therapy. This agent is still under investigation and is not available in the United States. Istaroxime, an inotrope with lusitropic properties, is also being investigated for its potential use in advanced HF patients. The current American College of Cardiology/American Heart Association, European Society of Cardiology, and Heart Failure Society of America guidelines indicate that, other than digoxin, inotropic agents should be reserved for patients presenting with acute decompensated HF and low-output states and reduced end-organ perfusion, who typically are admitted to an intensive care unit. These agents also are of benefit in advanced HF patients as a bridge to transplantation to optimize end-organ function and may be used in the outpatient setting, usually in patients with an implantable cardioverter-defibrillator. Finally, inotropes should be used to palliate symptoms in end-stage HF patients who have severe symptoms and are not candidates for heart transplantation or mechanical circulatory support.

Use of inotropic agents in patients with advanced heart failure: lessons from recent trials and hopes for new agents

Abnormalities of cardiac function, with high intraventricular filling pressure and low cardiac output, play a central role in patients with heart failure. Agents with inotropic properties are potentially useful to correct these abnormalities. However, with the exception of digoxin, no inotropic agent has been associated with favourable effects on outcomes. This is likely related to the mechanism of action of current agents, which is based on an increase in intracellular cyclic adenosine monophosphate and calcium concentrations. Novel agents acting through different mechanisms, such as sarcoplasmic reticulum calcium uptake, cardiac myosin and myocardial metabolism, have the potential to improve myocardial efficiency and lower myocardial oxygen consumption. These characteristics might allow a haemodynamic improvement in the absence of untoward effects on the clinical course and prognosis of the patients.

Modulation of beta-adrenergic receptor signaling in heart failure and longevity: targeting adenylyl cyclase type 5

Despite remarkable advances in therapy, heart failure remains a leading cause of morbidity and mortality. Although enhanced beta-adrenergic receptor stimulation is part of normal physiologic adaptation to either the increase in physiologic demand or decrease in cardiac function, chronic beta-adrenergic stimulation has been associated with increased mortality and morbidity in both animal models and humans. For example, overexpression of cardiac Gsalpha or beta-adrenergic receptors in transgenic mice results in enhanced cardiac function in young animals, but with prolonged overstimulation of this pathway, cardiomyopathy develops in these mice as they age. Similarly, chronic sympathomimetic amine therapy increases morbidity and mortality in patients with heart failure. Conversely, the use of beta-blockade has proven to be of benefit and is currently part of the standard of care for heart failure. It is conceivable that interrupting distal mechanisms in the beta-adrenergic receptor-G protein-adenylyl cyclase pathway may also provide targets for future therapeutic modalities for heart failure. Interestingly, there are two major isoforms of adenylyl cyclase (AC) in the heart (type 5 and type 6), which may exert opposite effects on the heart, i.e., cardiac overexpression of AC6 appears to be protective, whereas disruption of type 5 AC prolongs longevity and protects against cardiac stress. The goal of this review is to summarize the paradigm shift in the treatment of heart failure over the past 50 years from administering sympathomimetic amine agonists to administering beta-adrenergic receptor antagonists, and to explore the basis for a novel therapy of inhibiting type 5 AC.

Current use of pimobendan in canine patients with heart disease

Pimobendan is a drug with both inotropic and vasodilatory properties and is widely used for the treatment of heart failure in dogs. The best evidence regarding its efficacy is derived from several clinical studies of dogs with the two most common conditions that result in heart failure: dilated cardiomyopathy (DCM) and degenerative mitral valve disease (DMVD). The main studies addressing the effectiveness of pimobendan in dogs with DCM and DVMD are discussed in this article.

Agents with inotropic properties for the management of acute heart failure syndromes. Traditional agents and beyond

Treatment with inotropic agents is one of the most controversial topics in heart failure. Initial enthusiasm, based on strong pathophysiological rationale and apparent empirical efficacy, has been progressively limited by results of controlled trials and registries showing poorer outcomes of the patients on inotropic therapy. The use of these agents remains, however, potentially indicated in a significant proportion of patients with low cardiac output, peripheral hypoperfusion and end-organ dysfunction caused by heart failure. Limitations of inotropic therapy seem to be mainly related to their mechanisms of action entailing arrhythmogenesis, peripheral vasodilation, myocardial ischemia and damage, and possibly due to their use in patients without a clear indication, rather than to the general principle of inotropic therapy itself. This review will discuss the characteristics of the patients with a potential indication for inotropic therapy, the main data from registries and controlled trials, the mechanism of the untoward effects of these agents on outcomes and, lastly, perspectives with new agents with novel mechanisms of action.