Clinical use of inotropic therapy for heart failure: looking backward or forward? Part I: inotropic infusions during hospitalization

Inotropic Agents: Are We Still in the Middle of Nowhere?

Inotropes are prescribed to enhance myocardial contractility while vasopressors serve to improve vascular tone. Although these medications remain a life-saving therapy in cardiovascular clinical scenarios with hemodynamic impairment, the paucity of evidence on these drugs makes the choice of the most appropriate vasoactive agent challenging. As such, deep knowledge of their pharmacological and hemodynamic effects becomes crucial to optimizing hemodynamic profile while reducing the potential adverse effects. Given this perspective, it is imperative for cardiologists to possess a comprehensive understanding of the underlying mechanisms governing these agents and to discern optimal strategies for their application across diverse clinical contexts. Thus, we briefly review these agents' pharmacological and hemodynamic properties and their reasonable clinical applications in cardiovascular settings. Critical interpretation of available data and the opportunities for future investigations are also highlighted.

Continuous Intravenous Inotropic Support for Advanced Heart Failure: Palliative Considerations

The global prevalence of heart failure (HF) is increasing. Advancements in guideline-directed medical and device therapy have resulted in improved survival. Thus, there are more patients living - and living longer - with advanced HF. Only a small proportion of these patients are deemed appropriate for advanced surgical intervention (mechanical circulatory support or heart transplantation), and even if offered, some may decline such interventions if not aligned with their overall goals and values. Therefore, a growing number of patients with advanced HF receive chronic intravenous inotropic support (CIIS) for palliation of symptoms. Despite increased use, clinical evidence supporting use of palliative inotropes remains limited. However, available data suggest improvements in functional class, health-related quality of life (HRQoL) indicators, symptom burden, hemodynamic parameters, and possibly rehospitalization. While initial concerns regarding increased mortality have been assuaged in the modern era of guideline-directed medical therapy, palliative inotropes are certainly not without burden. Risks of infection and medication-related adverse effects, need for routine laboratory monitoring, frequent dressing changes, and presence of a reliable caregiver must be carefully considered prior to initiation. This review addresses pharmacology, guideline recommendations, benefits and burdens, considerations related to hospice and end-of-life care, and future directions of CIIS in advanced HF care.

Calcium and Heart Failure: How Did We Get Here and Where Are We Going?

The occurrence and prevalence of heart failure remain high in the United States as well as globally. One person dies every 30 s from heart disease. Recognizing the importance of heart failure, clinicians and scientists have sought better therapeutic strategies and even cures for end-stage heart failure. This exploration has resulted in many failed clinical trials testing novel classes of pharmaceutical drugs and even gene therapy. As a result, along the way, there have been paradigm shifts toward and away from differing therapeutic approaches. The continued prevalence of death from heart failure, however, clearly demonstrates that the heart is not simply a pump and instead forces us to consider the complexity of simplicity in the pathophysiology of heart failure and reinforces the need to discover new therapeutic approaches.

Angiotensin receptor-neprilysin inhibition in patients with acute decompensated heart failure: an expert consensus position paper

The short-term mortality and rehospitalization rates after admission for acute heart failure (AHF) remain high, despite the high level of adherence to contemporary practice guidelines. Observational data from non-randomized studies in AHF strongly support the in-hospital administration of oral evidence-based modifying chronic heart failure (HF) medications (i.e., b-blockers, ACE inhibitors, mineralocorticoid receptor antagonists) to reduce morbidity and mortality. Interestingly, a well-designed prospective randomized multicenter study (PIONEER-HF) showed an improved clinical outcome and stress/injury biomarker profile after in-hospital administration of sacubitril/valsartan (sac/val) as compared to enalapril, in hemodynamically stable patients with AHF. However, sac/val implementation during hospitalization remains suboptimal due to the lack of an integrated individualized plan or well-defined appropriateness criteria for transition to oral therapies, an absence of specific guidelines regarding dose selection and the up-titration process, and uncertainty regarding patient eligibility.

In the present expert consensus position paper, clinical practical recommendations are proposed, together with an action plan algorithm, to encourage and facilitate sac/val administration during hospitalization after an AHF episode with the aim of improving efficiencies of care and resource utilization.

Inodilators in septic shock: should these be used?

Septic shock involves a complex interaction between abnormal vasodilation, relative and/or absolute hypovolemia, myocardial dysfunction, and altered blood flow distribution to the tissues. Fluid administration, vasopressor support and inotropes, represent fundamental pieces of quantitative resuscitation protocols directed to assist the restoration of impaired tissue perfusion during septic shock. Indeed, current recommendations on sepsis management include the use of inotropes in the case of myocardial dysfunction, as suggested by a low cardiac output, increased filling pressures, or persisting signals of tissue hypoperfusion despite an adequate correction of intravascular volume and mean arterial pressure by fluid administration and vasopressor support. Evidence supporting the use of inotropes in sepsis and septic shock is mainly based on physiological studies. Most of them suggest a beneficial effect of inotropes on macro hemodynamics especially when sepsis coexists with myocardial dysfunction; others, however, have demonstrated variable results on regional splanchnic circulation, while others suggest favorable effects on microvascular distribution independently of its impact on cardiac output. Conversely, impact of inodilators on clinical outcomes in this context has been more controversial. Use of dobutamine has not been consistently related with more favorable clinical results, while systematic administration of levosimendan in sepsis do not prevent the development of multiorgan dysfunction, even in patients with evidence of myocardial dysfunction. Nevertheless, a recent metanalysis of clinical studies suggests that cardiovascular support regimens based on inodilators in sepsis and septic shock could provide some beneficial effect on mortality, while other one corroborated such effect on mortality specially in patients with proved lower cardiac output. Thus, using or not inotropes during sepsis and septic shock remains as controversy matter that deserves more research efforts.

Why has positive inotropy failed in chronic heart failure? Lessons from prior inotrope trials

Current pharmacological therapies for heart failure with reduced ejection fraction are largely either repurposed anti‐hypertensives that blunt overactivation of the neurohormonal system or diuretics that decrease congestion. However, they do not address the symptoms of heart failure that result from reductions in cardiac output and reserve. Over the last few decades, numerous attempts have been made to develop and test positive cardiac inotropes that improve cardiac haemodynamics. However, definitive clinical trials have failed to show a survival benefit. As a result, no positive inotrope is currently approved for long‐term use in heart failure. The focus of this state‐of‐the‐art review is to revisit prior clinical trials and to understand the causes for their findings. Using the learnings from those experiences, we propose a framework for future trials of such agents that maximizes their potential for success. This includes enriching the trials with patients who are most likely to derive benefit, using biomarkers and imaging in trial design and execution, evaluating efficacy based on a wider range of intermediate phenotypes, and collecting detailed data on functional status and quality of life. With a rapidly growing population of patients with advanced heart failure, the epidemiologic insignificance of heart transplantation as a therapeutic intervention, and both the cost and morbidity associated with ventricular assist devices, there is an enormous potential for positive inotropic therapies to impact the outcomes that matter most to patients.

Palliative care in heart failure

Palliative care (PC) is now recommended by all major cardiovascular societies for advanced heart failure (HF). PC is a philosophy of care that uses a holistic approach to address physical, psychosocial, and spiritual needs in patients with a terminal disease process. In HF, PC has been shown to improve symptoms and quality of life, facilitate advanced care planning, decrease hospital readmissions, and decrease hospital-associated healthcare costs. Although PC is still underutilized in HF, uptake is increasing. Specific strategies for successfully implementing PC in HF include early PC involvement, multidisciplinary collaboration, exploring patient values for end-of-life care, medical therapy (including both the addition of symptom-directed medications, as well as the removal of life-prolonging medications), and considerations regarding device therapy and mechanical support. Barriers to PC in HF include difficulties predicting the disease trajectory, patient and physician misconceptions, and lack of PC-trained physicians. Moving forward, PC will continue to be a key part of advanced HF care as our knowledge of this area grows.

Effects of intravenous home dobutamine in palliative end-stage heart failure on quality of life, heart failure hospitalization, and cost expenditure

Aims

In patients with palliative end‐stage heart failure, interventions that could provide symptomatic relief and prevent hospital admissions are important. Ambulatory continuous intravenous inotropes have been advocated by guidelines for such a purpose. We sought to determine the effect of intravenous dobutamine on symptomatic status, hospital stay, mortality, and cost expenditure.

Methods and results

All consecutive end‐stage heart failure patients not amenable for advanced therapies and discharged with continuous intravenous home dobutamine from a single tertiary centre between April 2011 and January 2017 were retrospectively analysed. Dobutamine (fixed dose) was infused through a single‐lumen central venous catheter with a small pump that was refilled by a nurse on a daily basis. Symptomatic status was longitudinally assessed as the change in New York Heart Association class and patient global assessment scale. Antecedent and incident heart failure hospitalizations were determined in a paired fashion, and cost impact was assessed. A total of 21 patients (age 77 ± 9 years) were followed up for 869 ± 647 days. At first follow‐up (6 ± 1 weeks) after the initiation of dobutamine, patients had a significant improvement in New York Heart Association class (−1.29 ± 0.64; P < 0.001), global assessment scale (<0.001), and N‐terminal pro‐brain natriuretic peptide (6247 vs. 2543 pg/mL; P = 0.033). Incident heart failure hospitalizations assessed at 3, 6, and 12 months were significantly reduced (P < 0.001 for all) in comparison with antecedent heart failure hospitalizations over the same time period. Cost expenditure was significantly lower at 3 (P < 0.001), 6 (P = 0.005), and 12 months (P = 0.001) after initiation of dobutamine. Mortality rate at 1 year was 48% with 9/12 (75%) patients dying at home, most often from progressive pump failure.

Conclusions

Continuous intravenous home dobutamine in patients with palliative end‐stage heart failure is feasible and associated with improved symptomatic status, heart failure hospitalizations, and health‐care‐related costs. Nevertheless, results should be interpreted in the context of the small and retrospective design. Larger studies are necessary to evaluate the effect of dobutamine in palliative end‐stage heart failure.

Continuous Cardiac Inotropes in Patients With End-Stage Heart Failure: An Evolving Experience

Heart failure (HF) experts recommend initiation of continuous inotrope therapy, such as milrinone or dobutamine, for clinically decompensating patients with stage D HF. Although originally intended to serve solely as a bridge to more definitive surgical therapies, more and more patients are receiving inotrope therapy for purely palliative purposes. In these cases, questions arise regarding care at the end of life. What criteria determine ongoing clinical benefit? Should the inotrope be continued until death? Should inotrope dosing be increased within recommended guidelines to improve symptoms? What is the role of inotropes in hospice care? Here, we describe such a case as a springboard to contemplate the evolving role of inotrope therapies and how hospice and palliative providers may interface with this rapidly developing face of advanced HF care.

Symptom management challenges in heart failure: pharmacotherapy considerations

Heart failure is a chronic, progressive illness that is increasing in prevalence in the USA. Patients with advanced heart failure experience a high symptom burden that is comparable to patients with advanced cancer. Palliative care, however, is underutilized in patients with heart failure, and symptoms may go untreated as the disease progresses. A combination of pharmacologic and non-pharmacologic interventions should be used to address symptoms and maintain quality of life. While there have been significant advances in evidence-based heart failure treatments in recent years, selection of appropriate palliative medications as symptoms progress is challenging due to limited clinical studies in this patient population. Medications that are commonly used for symptom management in other life-limiting illnesses may have little to no evidence in heart failure, or have undesirable cardiac effects that preclude use. Clinicians must extrapolate available clinical evidence and prescribing considerations relevant to heart failure to palliate symptoms as well as possible. The objectives of this paper are to review the most common and distressing symptoms in heart failure, analyze evidence, or lack thereof, for pharmacologic management of symptoms, and provide prescribing considerations based on side effect profiles and comorbid conditions.

Advanced heart failure: an appraisal of the potential of levosimendan in this end-stage scenario and some related ethical considerations

INTRODUCTION

The later stages of heart failure are characterized by a steady decline in quality of life. Clinical priorities should be to maintain functional capacity and quality of life. In the absence of sufficient organs for transplantation, options include left ventricular assist devices and inotropic support. Areas covered: We examined data published in the last two decades on the use of inotropes and inodilators in advanced heart failure. Expert commentary: In the literature, use of conventional inotropes, including adrenergic agonists and phosphodiesterase inhibitors, appears to be suboptimal for achieving the clinical priorities of late-stage heart failure. Evidence suggests instead that the calcium-sensitizing inodilator levosimendan, administered intermittently, delivers improvements in functional capacity and quality of life and does so with no adverse impact on life expectancy. At a terminal or near-terminal stage of heart failure, the therapeutic philosophy should shift towards meeting patients' existential priorities rather than traditional heart failure-centric targets.

Emerging Novel Therapies for Heart Failure

Heart function fails when the organ is unable to pump blood at a rate proportional to the body’s need for oxygen or when this function leads to elevated cardiac chamber filling pressures (cardiogenic pulmonary edema). Despite our sophisticated knowledge of heart failure, even so-called ejection fraction-preserved heart failure has high rates of mortality and morbidity. So, novel therapies are sorely needed. This review discusses current standard therapies for heart failure and launches an exploration into emerging novel treatments on the heels of recently-approved sacubitril and ivbradine. For example, Vasoactive Intestinal Peptide (VIP) is protective of the heart, so in the absence of VIP, VIP knockout mice have dysregulation in key heart failure genes: 1) Force Generation and Propagation; 2) Energy Production and Regulation; 3) Ca⁺² Cycling; 4) Transcriptional Regulators. VIP administration leads to coronary dilation in human subjects. In heart failure patients, VIP levels are elevated as a plausible endogenous protective effect. With the development of elastin polymers to stabilize VIP and prevent its degradation, VIP may therefore have a chance to satisfy the unmet need as a potential treatment for acute heart failure.

Glucagon Increases Beating Rate but Not Contractility in Rat Right Atrium. Comparison with Isoproterenol

This study evaluated the chronotropic and inotropic responses to glucagon in spontaneously beating isolated right atria of rat heart. For comparison, we also investigated the effects resulting from stimulating β-adrenoceptors with isoproterenol in this tissue. Isoproterenol increased both atrial frequency and contractility but glucagon only enhanced atrial rate. The transcript levels of glucagon receptors were about three times higher in sinoatrial node than in the atrial myocardium. Chronotropic responses to glucagon and isoproterenol were blunted by the funny current (If) inhibitor ZD 7288. Inhibitors of protein kinase A, H-89 and KT-5720 reduced the chronotropic response to glucagon but not to isoproterenol. Inhibition of ryanodine receptors and calcium/calmodulin dependent protein kinase II (important regulators of sarcoplasmic reticulum Ca2⁺ release), with ruthenium red and KN-62 respectively, failed to alter chronotropic responses of either glucagon or isoproterenol. Non selective inhibition of phosphodiesterase (PDE) with 3-isobutylmethylxantine or selective inhibition of PDE3 or PDE4 with cilostamide or rolipram respectively did not affect chronotropic effects of glucagon or isoproterenol. Our results indicate that glucagon increases beating rate but not contractility in rat right atria which could be a consequence of lower levels of glucagon receptors in atrial myocardium than in sinoatrial node. Chronotropic responses to glucagon or isoproterenol are mediated by If current but not by sarcoplasmic reticulum Ca2⁺ release, neither are regulated by PDE activity.

Clinical Characteristics and Outcomes of Intravenous Inotropic Therapy in Advanced Heart Failure

BACKGROUND

Inotrope use in heart failure treatment was associated with improved symptoms, but worse survival in clinical trials. However, these studies predated use of modern heart failure therapies. This study evaluates contemporary outcomes on long-term inotropes.

METHODS AND RESULTS

We collected baseline and postinotrope data on 197 patients discharged on inotropes between January 2007 and March 2013. Baseline characteristics, hemodynamic and clinical changes on inotropes, and survival were evaluated. Patients initiated on inotropes had refractory heart failure, with median baseline New York Heart Association class IV, cardiac index of 1.7 L/min per m(2), pulmonary capillary wedge pressure of 25.6 mm Hg, and left ventricular ejection fraction of 18.7%. Inotropes were used in patients listed for transplant or scheduled for left ventricular assist device (LVAD; 60 patients), in patients being evaluated for LVAD/transplant (20 patients), for stabilization pending cardiac resynchronization therapy/percutaneous coronary intervention (4 patients), in patients who were offered LVAD but chose inotropes (15 patients), and for palliation (98 patients). Milrinone was used in 84.8% and dobutamine in 15.2%. At the end of the study, 68 patients had died, 24 were weaned off inotropes, 23 were transplanted, 32 received LVADs, and 50 remained on inotropes. Patients who received inotropes for palliation or those who preferred inotropes over LVAD had median survival of 9.0 months (interquartile range, 3.1-37.1 months), actuarial 1-year survival of 47.6%, and 2-year survival of 38.4%. Of 60 patients who were placed on inotropes as a bridge to transplant/LVAD, 55 were successfully maintained on inotropes until transplant/LVAD.

CONCLUSIONS

Survival on inotropes for patients who are not candidates for transplant/LVAD is modestly better than previously reported, but remains poor. Inotropes are effective as a bridge to transplant/LVAD.

An in silico case study of idiopathic dilated cardiomyopathy via a multi-scale model of the cardiovascular system

Mathematical modelling has been used to comprehend the pathology and the assessment of different treatment techniques such as heart failure and left ventricular assist device therapy in the cardiovascular field. In this study, an in-silico model of the heart is developed to understand the effects of idiopathic dilated cardiomyopathy (IDC) as a pathological scenario, with mechanisms described at the cellular, protein and organ levels. This model includes the right and left atria and ventricles, as well as the systemic and pulmonary arteries and veins. First, a multi-scale model of the whole heart is simulated for healthy conditions. Subsequently, the model is modified at its microscopic and macroscopic spatial scale to obtain the characteristics of IDC. The extracellular calcium concentration, the binding affinity of calcium binding proteins and the maximum and minimum elastances have been identified as key parameters across all relevant scales. The modified parameters cause a change in (a) intracellular calcium concentration characterising cellular properties, such as calcium channel currents or the action potential, (b) the proteins being involved in the sliding filament mechanism and the proportion of the attached crossbridges at the protein level, as well as (c) the pressure and volume values at the organ level. This model allows to obtain insight and understanding of the effects of the treatment techniques, from a physiological and biological point of view.

Inotropes do not increase mortality in advanced heart failure

Inotrope use is one of the most controversial topics in the management of heart failure. While the heart failure community utilizes them and recognizes the state of inotrope dependency, retrospective analyses and registry data have overwhelmingly suggested high mortality, which is logically to be expected given the advanced disease states of those requiring their use. Currently, there is a relative paucity of randomized control trials due to the ethical dilemma of creating control groups by withholding inotropes from patients who require them. Nonetheless, results of such trials have been mixed. Many were also performed with agents no longer in use, on patients without an indication for inotropes, or at a time before automatic cardio-defibrillators were recommended for primary prevention. Thus, their results may not be generalizable to current clinical practice. In this review, we discuss current indications for inotrope use, specifically dobutamine and milrinone, depicting their mechanisms of action, delineating their patterns of use in clinical practice, defining the state of inotrope dependency, and ultimately examining the literature to ascertain whether evidence is sufficient to support the current view that these agents increase mortality in patients with heart failure. Our conclusion is that the evidence is insufficient to link inotropes and increased mortality in low output heart failure.

Elevation of Plasma Milrinone Concentrations in Stage D Heart Failure Associated With Renal Dysfunction

Purpose:

To determine steady state milrinone concentrations in patients with stage D heart failure (HF) with and without renal dysfunction

Methods:

We retrospectively identified patients with stage D HF at a single medical center on continuous milrinone infusion at the time of plasma collection for entry into a research registry database. Milrinone was prescribed and titrated to improve hemodynamic and clinical status by a cardiologist. Plasma samples were obtained at steady state milrinone concentrations. Patients were stratified by creatinine clearance (CrCl) into 4 groups: group 1 (CrCl >60 mL/min), group 2 (CrCl 60-30 mL/min), group 3 (CrCl <30 mL/min), and group 4 (intermittent hemodialysis). Retrospective chart review was performed to quantify the postmilrinone hemodynamic changes by cardiac catheterization and electrophysiologic changes by implantable cardiac defibrillator (ICD) interrogation.

Results:

A total of 29 patients were identified: group 1 (n = 14), group 2 (n = 10), group 3 (n = 3), and group 4 (n = 2). The mean infusion rate (0.391 ± 0.08 µg/kg/min) did not differ between groups ( P = 0.14). The mean milrinone concentration was 451± 243 ng/mL in group 1, 591 ± 293 ng/mL in group 2, 1575 ± 962 ng/mL in group 3, and 6252 ± 4409 ng/mL in group 4 ( P<0.05 compared to groups 1). There was no difference in postmilrinone hemodynamic improvements between the groups ( P=0.41). The ICD interrogation revealed limited comparisons, but 6 of the 8 postmilrinone ventricular tachycardia episodes requiring defibrillation occurred in group 4 patients.

Conclusion:

Patients with stage D HF having severe renal dysfunction have elevated milrinone concentrations. Future studies of milrinone concentrations are warranted to investigate the potential risk of life-threatening arrhythmias and potential dosing regimens in renal dysfunction.

Cardiorenal syndrome in acute decompensated heart failure

Cardiorenal syndrome (CRS) commonly occurs during treatment of acute decompensated heart failure (ADHF) and is associated with poor clinical outcome. The pathophysiology of CRS entails a complex interaction between hemodynamic alterations, including reduced renal perfusion, increased venous pressure and activation of multiple neurohormonal systems. Attempts to effectively treat congestion while preserving renal function in ADHF are often met with limited clinical success and often require therapeutic decisions that reflect a compromise between potential benefits and harm. At present, there is no evidence-based intervention specifically targeted at renal function. Recent Phase III randomized trials, using novel agents in patients with ADHF, have largely failed to demonstrate any benefits of therapy on renal and clinical outcomes. Early diagnosis of CRS using novel markers of tubular injury may allow for timely interventions and attenuate progression. Future studies are needed to further elucidate the pathophysiology of this complex syndrome and identify new potential targets for effective evidence-based treatments.

Novel therapies in acute and chronic heart failure

Despite past advances in the pharmacological management of heart failure, the prognosis of these patients remains poor, and for many, treatment options remain unsatisfactory. Additionally, the treatments and clinical outcomes of patients with acute decompensated heart failure have not changed substantially over the past few decades. Consequently, there is a critical need for new drugs that can improve clinical outcomes. In the setting of acute heart failure, new inotrops such as cardiac myosin activators and new vasodilators such as relaxin have been developed. For chronic heart failure with reduced ejection fraction, there are several new approaches that target multiple pathophysiological mechanism including novel blockers of the renin-angiotensin-aldosterone system (direct renin inhibitors, dual-acting inhibitors of the angiotensin II receptor and neprilysin, aldosterone synthase inhibitors), ryanodine receptor stabilizers, and SERCA activators. Heart failure with preserved ejection fraction represents a substantial therapeutic problem as no therapy has been demonstrated to improve symptoms or outcomes in this condition. Newer treatment strategies target specific structural and functional abnormalities that lead to increased myocardial stiffness. Dicarbonyl-breaking compounds reverse advanced glycation-induced cross-linking of collagen and improve the compliance of aged and/or diabetic myocardium. Modulation of titin-dependent passive tension can be achieved via phosphorylation of a unique sequence on the extensible region of the protein. This review describes the pathophysiological basis, mechanism of action, and available clinical efficacy data of drugs that are currently under development. Finally, new therapies for the treatment of heart failure complications, such as pulmonary hypertension and anemia, are discussed.

Myocardial G protein receptor-coupled kinase expression correlates with functional parameters and clinical severity in advanced heart failure

BACKGROUND

In heart failure (HF), sympathetic hyperactivation induces deleterious effects in myocardial β-adrenergic signaling, with receptor down-regulation and desensitization mediated by G protein receptor-coupled kinases (GRKs). We hypothesised that changes in GRK isoforms may be associated with clinical status in advanced HF, using the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) scale.

METHODS

We included 31 patients with advanced HF undergoing transplantation. According to INTERMACS profiles, mRNA and protein levels of GRK isoforms in left ventricular (LV) myocardium were analyzed and compared with nonfailing LV samples.

RESULTS

In failing LV myocardium, GRK2 and GRK5 (but not GRK3) protein was up-regulated compared with control samples. Among HF patients, an increase in GRK2 and GRK5 mRNA and protein abundance was observed in β-agonist-treated patients (vs β-blockers: P < .05) and in higher-risk INTERMACS status (profiles 2 and 3 vs 4 and 5: P < .05). A significant negative correlation of GRK2 expression with LV stroke volume supported these findings.

CONCLUSIONS

Increased GRK2 correlates with clinical severity using the INTERMACS scale and LV stroke volume, supporting it as a potential target in advanced HF. These changes are paralleled by GRK5 expression in the failing myocardium, suggesting a relevant role in human HF.

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.

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.

Usefulness of cardiac index and peak exercise oxygen consumption for determining priority for cardiac transplantation

Decisions regarding cardiac transplantation listing are difficult in patients with heart failure who have relatively discordant peak exercise oxygen consumption (Vo(2)) and cardiac index (CI) values. One hundred five patients with heart failure who underwent cardiopulmonary exercise testing and right-sided cardiac catheterization for transplantation evaluation were studied. Patients were divided into 4 groups on the basis of peak Vo(2) and CI: group 1, Vo(2) > or = 12 ml/min/kg, CI > or = 1.8 L/min/m(2) (n = 30); group 2, Vo(2) > or = 12 ml/min/kg, CI <1.8, L/min/m(2) (n = 27); group 3, Vo(2) <12 ml/min/kg, CI > or = 1.8 L/min/m(2) (n = 25); and group 4, Vo(2) <12 ml/min/kg, CI <1.8 L/min/m(2) (n = 23). Groups were compared for event-free (death or ventricular assist device) survival. The overall CI was 1.9 + or - 0.4 L/min/m(2) and peak Vo(2) was 12.4 + or - 2.8 ml/min/kg; values in the 4 groups were as follows: group 1, peak Vo(2) 14.7 + or - 2.1 ml/min/kg, CI 2.2 + or - 0.3 L/min/m(2); group 2, peak VO(2) 14.2 + or - 1.3 ml/min/kg, CI 1.5 + or - 0.2 L/min/m(2); group 3, peak Vo(2) 10.2 + or - 1.3 ml/min/kg, CI 2.1 + or - 0.3 L/min/m(2); and group 4, peak Vo(2) 9.7 + or - 2.0 ml/min/kg, CI 1.6 + or - 0.2 L/min/m(2). After a median follow-up period of 3.7 years, 28 patients (26.0%) had events. Event-free survival was 96%, 95%, 96%, and 79% for 6 months (p = 0.04); 88%, 81%, 90%, and 73% for 12 months (p = 0.09); 88%, 73%, 85%, and 65% for 18 months (p = 0.11); and 83%, 73%, 79%, and 53% for 24 months (p = 0.06) for groups 1 to 4, respectively. Median survival was 5.1, 3.0, 3.9, and 2.6 years, respectively, in groups 1 to 4 (p = 0.052). In conclusion, almost half the patients had relatively discordant peak Vo(2) and CI measurements. Patients with lower peak Vo(2) values but relatively preserved CI values had survival comparable to post-transplantation survival, whereas those with low CI but preserved Vo(2) had a lower survival rate. These results suggest that the former group may be safely monitored on medical therapy, whereas the latter may benefit from early listing.

Why, when, and how to assess pulmonary congestion in heart failure: pathophysiological, clinical, and methodological implications

Acute heart failure syndrome (AHFS) is a major public health problem. It is defined as gradual or rapid change in heart failure (HF) signs and symptoms, which often results in an unplanned hospitalization and a need for urgent therapy. Many evidence-based pharmacologic, device, and surgical treatment for HF are available or under development. Despite these new treatments and improvement in survival, hospitalizations in HF have steadily increased over the last 30 years, and the post-discharge prognosis of patients hospitalized with AHFS remains poor (Gheorghiade et al. Circulation 112:3958-3968, 2005; Fonarow et al. Rev Cardiovasc Med 4:S21-30, 2003). Most hospitalizations for AHFS are related to "congestion" rather than to low cardiac output. The definition, identification, quantification, and monitoring of congestion are therefore essential in AHFS. The purpose of this article is: (1) to characterize the different types of hemodynamic, clinical, and pulmonary congestion in AHFS; (2) to focus on the different possible ways to assess pulmonary congestion (probably the most important, and up to now the most diagnostically elusive of the three types of congestions); (3) to propose new possible ways to implement objective and user-friendly measures of pulmonary congestion in clinical and scientific decision-making in AHFS in the near future.

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.

Management of end-stage heart failure: a perspective on the Arab Gulf states

The ever expanding epidemic of end-stage heart failure represents one of the greatest challenges of modern cardiovascular medicine. With medical treatments hampered by significant limitations, physicians caring for patients with advanced heart disease have turned to cardiac transplantation and durable mechanical circulatory assist devices as definitive therapies. These advanced therapeutic modalities are not widely available outside the United States and Europe, but nevertheless offer enormous potential for patients in the Arab Gulf suffering from end-stage heart failure. This review will discuss the management of end-stage heart failure in the Gulf States, with an emphasis on therapies best utilized within a framework of regional cooperation and coordination.

Are scores useful in advanced heart failure?

Advanced heart failure (HF) is becoming an increasingly challenging problem as more patients with this disease are living longer, yet experiencing its inexorable progression. Adding to this complex matter, there are different views on how to define advanced HF, whereby an acute decompensation episode does not necessarily indicate advanced disease. Several scores have been described aiming at a better prognostic performance across the HF spectrum. These include the Heart Failure Survival Score, the Seattle Heart Failure Model, the Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure predictive schemes, the Acute Decompensated Heart Failure National Registry regression tree discrimination, among others. Most scoring systems have been built based on outpatient populations or recently hospitalized HF subjects. The setting of advanced HF has not gained much attention as far as prognostication is concerned, and yet there lies potentially challenging decision-making situations where issues, such as heart transplantation, use of costly devices and end-of-life questions, are raised.

Effects of istaroxime on diastolic stiffness in acute heart failure syndromes: results from the Hemodynamic, Echocardiographic, and Neurohormonal Effects of Istaroxime, a Novel Intravenous Inotropic and Lusitropic Agent: a Randomized Controlled Trial in Patients Hospitalized with Heart Failure (HORIZON-HF) trial

BACKGROUND

Istaroxime is a novel intravenous agent with inotropic and lusitropic properties related to inhibition of the Na+/K+ adenosine triphosphatase and stimulation of sarcoplasmic reticulum calcium adenosine triphosphatase activity. We analyzed data from HORIZON-HF, a randomized, controlled trial evaluating the short-term effects of istaroxime in patients hospitalized with heart failure and left ventricular ejection fraction < or = 35% to test the hypothesis that istaroxime improves diastolic stiffness in acute heart failure syndrome.

METHODS

One hundred twenty patients were randomized 3:1 (istaroxime/placebo) to a continuous 6-hour infusion of 1 of 3 doses of istaroxime or placebo. All patients underwent pulmonary artery catheterization and comprehensive 2-dimensional/Doppler and tissue Doppler echocardiography at baseline and at the end of the 6-hour infusion. We quantified diastolic stiffness using pressure-volume analysis and tissue Doppler imaging of the lateral mitral annulus (E').

RESULTS

Baseline characteristics were similar among all groups, with mean age 55 +/- 11 years, 88% men, left ventricular ejection fraction 27% +/- 7%, systolic blood pressure (SBP) 116 +/- 13 mm Hg, and pulmonary capillary wedge pressure (PCWP) 25 +/- 5 mm Hg. Istaroxime administration resulted in an increase in E' velocities, whereas there was a decrease in E' in the placebo group (P = .048 between groups). On pressure-volume analysis, istaroxime decreased end-diastolic elastance (P = .0001). On multivariate analysis, increasing doses of istaroxime increased E' velocity (P = .043) and E-wave deceleration time (P = .001), and decreased E/E' ratio (P = .047), after controlling for age, sex, baseline ejection fraction, change in PCWP, and change in SBP.

CONCLUSIONS

Istaroxime decreases PCWP, increases SBP, and decreases diastolic stiffness in patients with acute heart failure syndrome.

Prognosis on chronic dobutamine or milrinone infusions for stage D heart failure

BACKGROUND

There are no published clinical trials comparing dobutamine with milrinone in outpatients with stage D heart failure on continuous inotropes.

METHODS AND RESULTS

In a retrospective analysis of 112 inotrope-dependent patients with stage D heart failure who were not transplant candidates at enrollment, we investigated the relationship between choice of dobutamine or milrinone and mortality. Half the patients were on dobutamine (mean dose, 5.4+/-2.5 microg/kg per minute) and half on milrinone (mean dose, 0.4+/-0.2 microg/kg per minute). Those on dobutamine tended to be older (63 years old versus 54 years old), male (86% versus 79%), and fewer had implantable cardioverter-defibrillators (57% versus 74%). During a median follow-up time of 130 days (range, 2 to 2345 days), there were 85 deaths (76% of cohort) and 55 rehospitalizations. Use of dobutamine compared with milrinone was associated with higher all-cause mortality in an unadjusted analysis (hazard ratio [HR], 1.63; 95% CI, 1.06 to 2.52; P<0.03). However, this association was not significant after adjustment for baseline characteristics in the full cohort (N=112; HR, 0.99; 95% CI 0.5 to 1.97; P=0.98) or propensity-matched cohort (N=70; HR, 0.94; 95% CI 0.48 to 1.85; P=0.86).

CONCLUSIONS

In this single-center retrospective study, there were no mortality differences between chronic intravenous dobutamine or milrinone in patients with stage D heart failure being discharged from the hospital. The high mortality in this group selected for inotrope dependence warrants careful consideration of all options and priorities for further care.

Sodium nitroprusside for advanced low-output heart failure

OBJECTIVES

This study was designed to examine the safety and efficacy of sodium nitroprusside (SNP) for patients with acute decompensated heart failure (ADHF) and low-output states.

BACKGROUND

Inotropic therapy has been predominantly used in the management of patients with ADHF presenting with low cardiac output.

METHODS

We reviewed all consecutive patients with ADHF admitted between 2000 and 2005 with a cardiac index < or =2 l/min/m(2) for intensive medical therapy including vasoactive drugs. Administration of SNP was chosen by the attending clinician, nonrandomized, and titrated to a target mean arterial pressure of 65 to 70 mm Hg.

RESULTS

Compared with control patients (n = 97), cases treated with SNP (n = 78) had significantly higher mean central venous pressure (15 vs. 13 mm Hg; p = 0.001), pulmonary capillary wedge pressure (29 vs. 24 mm Hg; p = 0.001), but similar demographics, medications, and renal function at baseline. Use of SNP was not associated with higher rates of inotropic support or worsening renal function during hospitalization. Patients treated with SNP achieved greater improvement in hemodynamic measurements during hospitalization, had higher rates of oral vasodilator prescription at discharge, and had lower rates of all-cause mortality (29% vs. 44%; odds ratio: 0.48; p = 0.005; 95% confidence interval: 0.29 to 0.80) without increase in rehospitalization rates (58% vs. 56%; p = NS).

CONCLUSIONS

In patients with advanced, low-output heart failure, vasodilator therapy used in conjunction with optimal current medical therapy during hospitalization might be associated with favorable long-term clinical outcomes irrespective of inotropic support or renal dysfunction and remains an excellent therapeutic choice in hospitalized ADHF patients.

Management of acute decompensated heart failure

Acute decompensated heart failure is the most common cause for hospitalization among patients over 65 years of age. It may result from new onset of ventricular dysfunction or, more typically, exacerbation of chronic heart failure symptoms. In-hospital mortality remains high for both systolic and diastolic forms of the disease. Therapy is largely empirical as few randomized, controlled trials have focused on this population and consensus practice guidelines are just beginning to be formulated. Treatment should be focused upon correction of volume overload, identifying potential precipitating causes, and optimizing vasodilator and beta-adrenergic blocker therapy. The majority of patients (>90%) will improve without the use of positive inotropic agents, which should be reserved for patients with refractory hypotension, cardiogenic shock, end-organ dysfunction, or failure to respond to conventional oral and/or intravenous diuretics and vasodilators. The role of aldosterone antagonists, biventricular pacing, and novel pharmacological agents including vasopressin antagonists, endothelin blockers, and calcium-sensitizing agents is also reviewed.

Stress-Induced Wall Motion Abnormalities with Low-Dose Dobutamine Infusion Indicate the Presence of Severe Disease and Vulnerable Myocardium

BACKGROUND

Patients with left ventricular (LV) systolic dysfunction due to coronary artery disease (CAD) may develop stress-induced wall motion abnormalities (SWMA) with low-dose (10 microg/kg/min) dobutamine infusion. The clinical significance of low-dose SWMA is unknown.

OBJECTIVE

We investigated the clinical, hemodynamic and angiographic correlates of low-dose SWMA in patients with chronic ischemic LV systolic dysfunction.

METHODS

Seventy patients with chronic ischemic LV systolic dysfunction who had dobutamine stress echocardiography were studied. Clinical, hemodynamic, and angiographic parameters at rest and low-dose were compared between 38 patients (mean ejection fraction (EF) of 30 +/- 8%) with low-dose SWMA and 32 patients (EF 30 +/- 11%) without low-dose SWMA.

RESULTS

Multivariate analysis showed that the number of coronary territories with severe disease (stenosis > or =70%)(P = 0.001, RR = 6.3) was an independent predictor of low-dose SWMA. An increasing number of collateral vessels protected patients from low-dose SWMA (P = 0.011, RR = 0.25). A higher resting heart rate was a negative predictor of low-dose SWMA (P = 0.015, RR = 0.92) but no other hemodynamic variables were predictors. In the patients with low-dose SMA, regions with low-dose SWMA were more likely to be supplied by vessels with severe disease than regions without low-dose SWMA (92% vs 58%, P < 0.001).

CONCLUSION

In patients with ischemic LV systolic dysfunction, the extent of severe disease and a lower numbers of collaterals predict the occurrence of low-dose SWMA. Low-dose SWMA is a highly specific marker for severe disease.

The confounding issue of comorbid renal insufficiency

The United States is currently beleaguered by twin epidemics, heart failure (HF) and renal insufficiency (RI). HF and RI frequently coexist in the same patient, and this conjunction, often called the "cardiorenal syndrome," has important therapeutic and prognostic implications. Approximately 60% to 80% of patients hospitalized for HF have at least stage III renal dysfunction as defined by the National Kidney Foundation (NKF), and this comorbid RI is associated with significantly increased morbidity and mortality risk. Numerous studies have demonstrated that in patients with HF, indices of renal function are the most powerful independent mortality risk predictors. Comorbid RI can result from both intrinsic renal disease and inadequate renal perfusion. Atherosclerosis, renal vascular disease, diabetes mellitus, and hypertension are significant precursors of both HF and RI. Moreover, diminished renal perfusion is frequently a consequence of the hemodynamic changes associated with HF and its treatment. Both HF and RI stimulate neurohormonal activation, increasing both preload and afterload and reducing cardiac output. Inotropic agents augment this neurohormonal activation. In addition, diuretics can produce hypovolemia and intravenous vasodilators can cause hypotension, further diminishing renal perfusion. Management of these patients requires successfully negotiating the delicate balance between adequate volume reduction and worsening renal function. Despite this, few evidence-based data are available to guide management decisions, indicating a compelling need for additional studies in this patient population.

Beta-blocker use in decompensated heart failure

Despite the current advances in treatment, acute decompensated heart failure accounts for more than 1 million hospital admissions annually. Many of the patients hospitalized are already receiving long-term treatment with beta-blockers. For patients who receive full dose beta-blocker therapy and suffer acute decompensated heart failure, clinicians face two key questions: what to do, if anything, with the dosage of beta-blocker and what is the best way to integrate inotropic and beta-blocker therapies for patients who require inotropes. This article discusses these issues and reviews the available literature. Because these topics have received little systematic evaluation, we also present our clinical approaches to these problems.

Perioperative management of chronic heart failure

Heart failure (HF) is one of the few cardiac conditions that is increasing. Despite a better understanding of how hormones and other signaling systems underlie the pathophysiology, and despite improved outcomes from pharmacologic therapy, many HF patients receive no effective treatment. Patients with HF commonly require medical diagnosis and management in operating rooms and critical care units; thus anesthesiologists are obliged to remain up-to-date both with advances in outpatient (chronic) medical management and with inpatient treatments for acute exacerbations of HF. Accordingly, we reviewed angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-adrenergic receptor blockers, and aldosterone antagonists because these drugs prolong life and are included in current clinical practice guidelines for treating patients with chronic HF. We also reviewed the implications of chronic HF for patients undergoing surgery and anesthesia and discuss how best to provide intensive treatment for acute exacerbations of symptoms, such as might be caused by excessive intravascular volume, inappropriate drug "holidays," or worsening of the underlying cardiac disease.

An Overview of Inotropic Agents

The use of inotropic agents has been surrounded by many controversies. Recent guidelines for the treatment of patients with chronic and acute heart failure have elucidated some of the issues, but many remain. As a result, a substantial variability in the use of agents between institutions and caregivers remains, which mainly results from the lack of uniform data in the literature. Prospective randomized trials with a long-term follow-up and sufficient power are clearly needed, and a number of trials are currently in progress.

A review of the natriuretic hormone system's diagnostic and therapeutic potential in critically ill children

OBJECTIVE

To review the natriuretic hormone system and discuss its diagnostic, prognostic, and therapeutic potential in critically ill children.

DATA SOURCE

A thorough literature search of MEDLINE was performed using search terms including heart defects, congenital; cardiopulmonary bypass, atrial natriuretic factor; natriuretic peptide, brain; carperitide; nesiritide. Preclinical and clinical investigations and review articles were identified that describe the current understanding of the natriuretic hormone system and its role in the regulation of vascular tone and fluid balance in healthy adults and children and in those with underlying cardiac, pulmonary, and renal disease.

RESULTS

A predictable activation of the natriuretic hormone system occurs in children with congenital heart disease and congestive heart failure. Further study is needed to confirm preliminary reports that measurement of natriuretic hormone levels in critically ill children provides diagnostic and prognostic information, as has been demonstrated in adult cardiac populations. Natriuretic hormone infusions provide favorable hemodynamic changes and symptomatic relief when used in adults with decompensated congestive heart failure, and uncontrolled case series suggest that similar benefits may exist in children. The biological activity of the natriuretic hormone system may be decreased following pediatric cardiopulmonary bypass, and additional studies are needed to determine whether natriuretic hormone infusions provide clinical benefit in the postoperative period. Preliminary reports suggest that natriuretic hormone infusions cause physiologic improvements in adults with acute lung injury and asthma but not in those with acute renal failure.

CONCLUSIONS

Although important perturbations of the natriuretic hormone system occur in critically ill infants and children, further investigation is needed before the measurement of natriuretic peptides and the use of natriuretic hormone infusions are incorporated into routine practice.