Hemodynamic and clinical limitations of long-term inotropic therapy with amrinone in patients with severe chronic heart failure

Consequences of Discontinuing Long-Term Drug Treatment in Patients With Heart Failure and Reduced Ejection Fraction

There is uncertainty regarding the clinical effects of discontinuation of drugs for heart failure after long-term use. The withdrawal of long-term treatment can follow 1 of 4 distinct patterns: 1) loss of on-treatment effect with no observed changes following discontinuation (eg, prazosin); 2) attenuation or loss of on-treatment effect with rebound clinical worsening following discontinuation (eg, nitroprusside); 3) persistence of deleterious on-treatment effect followed by clinical worsening after discontinuation (eg, milrinone and flosequinan); and 4) persistence of favorable on-treatment effect followed by clinical worsening after discontinuation (eg, digoxin and sodium-glucose cotransporter 2 inhibitors). Persuasive evidence for persistence of efficacy has been demonstrated for the use of digoxin, diuretic agents, sodium-glucose cotransporter 2 inhibitors, and (to a limited extent) for angiotensin-converting enzyme inhibitors. Available evidence for worsening of clinical status following the withdrawal of neurohormonal antagonists largely consists of observational studies. However, their findings are difficult to interpret because of considerable confounding related to the fact that drugs were withdrawn for clinical reasons, which represented a more important contributor to the poor outcome of these patients than the withdrawal of an effective drug. Nevertheless, the totality of available evidence points to a meaningful clinical deterioration within a few weeks following the withdrawal for most drugs that have been evaluated for the treatment of heart failure. These findings suggests that that our current emphasis on the implementation of foundational drugs needs to include an equally important emphasis to avoid even short-term gaps in treatment.

The First Dedicated Comprehensive Heart Failure Program in the United States: The Division of Circulatory Physiology at Columbia Presbyterian (1992-2004)

The first dedicated multidisciplinary heart failure program in the United States was founded as the Division of Circulatory Physiology at the Columbia University College of Physicians & Surgeons in 1992. The Division was administratively and financially independent of the Division of Cardiology and grew to 24 faculty members at its peak. Its administrative innovations included (1) a comprehensive full-integrated service line, with 2 differentiated clinical teams, one devoted to drug therapy and the other to heart transplantation and ventricular assist devices; (2) a nurse specialist/physician assistant-led clinical service; and (3) a financial structure independent of (and not supported by) other cardiovascular medical or surgical services. The division had 3 overarching missions: (1) to promote a unique career development path for each faculty member to be linked to recognition in a specific area of heart failure expertise; (2) to change the trajectory and enhance the richness of intellectual discourse in the discipline of heart failure, so as to foster an understanding of fundamental mechanisms and to develop new therapeutics; and (3) to provide optimal medical care to patients and to promote the ability of other physicians to provide optimal care. The major research achievements of the division included (1) the development of beta-blockers for heart failure, from initial hemodynamic assessments to proof-of-concept studies to large-scale international trials; (2) the development and definitive assessment of flosequinan, amlodipine, and endothelin antagonists; (3) initial clinical trials and concerns with nesiritide; (4) large-scale trials evaluating dosing of angiotensin converting-enzyme inhibitors and the efficacy and safety of neprilysin inhibition; (5) identification of key mechanisms in heart failure, including neurohormonal activation, microcirculatory endothelial dysfunction, deficiencies in peripheral vasodilator pathways, noncardiac factors in driving dyspnea, and the first identification of subphenotypes of heart failure and a preserved ejection fraction; (6) the development of a volumetric approach to the assessment of myocardial shortening; (7) conceptualization and early studies of cardiac contractility modulation as a treatment for heart failure; (8) novel approaches to the identification of cardiac allograft rejection and new therapeutics to prevent allograft vasculopathy; and (9) demonstration of the effect of left ventricular assist devices to induce reverse remodeling, and the first randomized trial showing a survival benefit with ventricular assist devices. Above all, the division served as an exceptional incubator for a generation of leaders in the field of heart failure.

Serum response factor deletion 5 regulates phospholamban phosphorylation and calcium uptake

AIMS

Pediatric dilated cardiomyopathy (pDCM) is characterized by unique age-dependent molecular mechanisms that include myocellular responses to therapy. We previously showed that pDCM, but not adult DCM patients respond to phosphodiesterase 3 inhibitors (PDE3i) by increasing levels of the second messenger cAMP and consequent phosphorylation of phospholamban (PLN). However, the molecular mechanisms involved in the differential pediatric and adult response to PDE3i are not clear.

METHODS AND RESULTS

Quantification of serum response factor (SRF) isoforms from the left ventricle of explanted hearts showed that PDE3i treatment affects expression of SRF isoforms in pDCM hearts. An SRF isoform lacking exon 5 (SRFdel5) was highly expressed in the hearts of pediatric, but not adult DCM patients treated with PDE3i. To determine the functional consequence of expression of SRFdel5, we overexpressed full length SRF or SRFdel5 in cultured cardiomyocytes with and without adrenergic stimulation. Compared to a control adenovirus, expression of SRFdel5 increased phosphorylation of PLN, negatively affected expression of the phosphatase that promotes dephosphorylation of PLN (PP2Cε), and promoted faster calcium reuptake, whereas expression of full length SRF attenuated calcium reuptake through blunted phosphorylation of PLN.

CONCLUSIONS

Taken together, these data indicate that expression of SRFdel5 in pDCM hearts in response to PDE3i contributes to improved function through regulating PLN phosphorylation and thereby calcium reuptake.

Molecular, Cellular, and Clinical Evidence That Sodium-Glucose Cotransporter 2 Inhibitors Act as Neurohormonal Antagonists When Used for the Treatment of Chronic Heart Failure

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of cardiovascular death and hospitalization for heart failure in patients with chronic heart failure. Initially, these drugs were believed to have a profile similar to diuretics or hemodynamically active drugs, but they do not rapidly reduce natriuretic peptides or cardiac filling pressures, and they exert little early benefit on symptoms, exercise tolerance, quality of life, or signs of congestion. Clinically, the profile of SGLT2 inhibitors resembles that of neurohormonal antagonists, whose benefits emerge gradually during sustained therapy. In experimental models, SGLT2 inhibitors produce a characteristic pattern of cellular effects, which includes amelioration of oxidative stress, mitigation of mitochondrial dysfunction, attenuation of proinflammatory pathways, and a reduction in myocardial fibrosis. These cellular effects are similar to those produced by angiotensin converting enzyme inhibitors, β-blockers, mineralocorticoid receptor antagonists, and neprilysin inhibitors. At a molecular level, SGLT2 inhibitors induce transcriptional reprogramming of cardiomyocytes that closely mimics that seen during nutrient deprivation. This shift in signaling activates the housekeeping pathway of autophagy, which clears the cytosol of dangerous cytosolic constituents that are responsible for cellular stress, thereby ameliorating the development of cardiomyopathy. Interestingly, similar changes in cellular signaling and autophagic flux have been seen with inhibitors of the renin-angiotensin system, β-blockers, mineralocorticoid receptor antagonists, and neprilysin inhibitors. The striking parallelism of these molecular, cellular, and clinical profiles supports the premise that SGLT2 inhibitors should be regarded as neurohormonal antagonists when prescribed for the treatment of heart failure with a reduced ejection fraction.

Pathogenesis and pathophysiology of heart failure with reduced ejection fraction: translation to human studies

Heart failure represents the end result of different pathophysiologic processes, which culminate in functional impairment. Regardless of its aetiology, the presentation of heart failure usually involves symptoms of pump failure and congestion, which forms the basis for clinical diagnosis. Pathophysiologic descriptions of heart failure with reduced ejection fraction (HFrEF) are being established. Most commonly, HFrEF is centred on a reactive model where a significant initial insult leads to reduced cardiac output, further triggering a cascade of maladaptive processes. Predisposing factors include myocardial injury of any cause, chronically abnormal loading due to hypertension, valvular disease, or tachyarrhythmias. The pathophysiologic processes behind remodelling in heart failure are complex and reflect systemic neurohormonal activation, peripheral vascular effects and localised changes affecting the cardiac substrate. These abnormalities have been the subject of intense research. Much of the translational successes in HFrEF have come from targeting neurohormonal responses to reduced cardiac output, with blockade of the renin-angiotensin-aldosterone system (RAAS) and beta-adrenergic blockade being particularly fruitful. However, mortality and morbidity associated with heart failure remains high. Although systemic neurohormonal blockade slows disease progression, localised ventricular remodelling still adversely affects contractile function. Novel therapy targeted at improving cardiac contractile mechanics in HFrEF hold the promise of alleviating heart failure at its source, yet so far none has found success. Nevertheless, there are increasing calls for a proximal, 'cardiocentric' approach to therapy. In this review, we examine HFrEF therapy aimed at improving cardiac function with a focus on recent trials and emerging targets.

A PDE3A Promoter Polymorphism Regulates cAMP-Induced Transcriptional Activity in Failing Human Myocardium

BACKGROUND

The phosphodiesterase 3A (PDE3A) gene encodes a PDE that regulates cardiac myocyte cyclic adenosine monophosphate (cAMP) levels and myocardial contractile function. PDE3 inhibitors (PDE3i) are used for short-term treatment of refractory heart failure (HF), but do not produce uniform long-term benefit.

OBJECTIVES

The authors tested the hypothesis that drug target genetic variation could explain clinical response heterogeneity to PDE3i in HF.

METHODS

PDE3A promoter studies were performed in a cloned luciferase construct. In human left ventricular (LV) preparations, mRNA expression was measured by reverse transcription polymerase chain reaction, and PDE3 enzyme activity by cAMP-hydrolysis.

RESULTS

The authors identified a 29-nucleotide (nt) insertion (INS)/deletion (DEL) polymorphism in the human PDE3A gene promoter beginning 2,214 nt upstream from the PDE3A1 translation start site. Transcription factor ATF3 binds to the INS and represses cAMP-dependent promoter activity. In explanted failing LVs that were homozygous for PDE3A DEL and had been treated with PDE3i pre-cardiac transplantation, PDE3A1 mRNA abundance and microsomal PDE3 enzyme activity were increased by 1.7-fold to 1.8-fold (p < 0.05) compared with DEL homozygotes not receiving PDE3i. The basis for the selective up-regulation in PDE3A gene expression in DEL homozygotes treated with PDE3i was a cAMP response element enhancer 61 nt downstream from the INS, which was repressed by INS. The DEL homozygous genotype frequency was also enriched in patients with HF.

CONCLUSIONS

A 29-nt INS/DEL polymorphism in the PDE3A promoter regulates cAMP-induced PDE3A gene expression in patients treated with PDE3i. This molecular mechanism may explain response heterogeneity to this drug class, and may inform a pharmacogenetic strategy for a more effective use of PDE3i in HF.

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.

Acute isoproterenol leads to age-dependent arrhythmogenesis in guinea pigs

Sudden cardiac death from ventricular arrhythmias is more common in adult patients with with heart failure compared with pediatric patients with heart failure. We identified age-specific differences in arrhythmogenesis using a guinea pig model of acute β-adrenergic stimulation. Young and adult guinea pigs were exposed to the β-adrenergic agonist isoproterenol (ISO; 0.7 mg/kg) for 30 min in the absence or presence of flecainide (20 mg/kg), an antiarrhythmic that blocks Na⁺ and ryanodine channels. Implanted cardiac monitors (Reveal LINQ, Medtronic) were used to monitor heart rhythm. Alterations in phosphorylation and oxidation of ryanodine receptor 2 (RyR2) were measured in left ventricular tissue. There were age-specific differences in arrhythmogenesis and sudden death associated with acute β-adrenergic stimulation in guinea pigs. Young and adult guinea pigs developed arrhythmias in response to ISO; however, adult animals developed significantly more premature ventricular contractions and experienced higher arrhythmia-related mortality than young guinea pigs treated with ISO. Although there were no significant differences in the phosphorylation of left ventricular RyR2 between young and adult guinea pigs, adult guinea pigs exposed to acute ISO had significantly more oxidation of RyR2. Flecainide treatment significantly improved survival and decreased the number of premature ventricular contractions in young and adult animals in association with lower RyR2 oxidation. Adult guinea pigs had a greater propensity to develop arrhythmias and suffer sudden death than young guinea pigs when acutely exposed to ISO. This was associated with higher oxidation of RyR2. The incidence of sudden death can be rescued with flecainide treatment, which decreases RyR2 oxidation. NEW & NOTEWORTHY Clinically, adult patients with heart failure are more likely to develop arrhythmias and sudden death than pediatric patients with heart failure. In the present study, older guinea pigs also showed a greater propensity to arrhythmias and sudden death than young guinea pigs when acutely exposed to isoproterenol. Although there are well-described age-related cardiac structural changes that predispose patients to arrhythmogenesis, the present data suggest contributions from dynamic changes in cellular signaling also play an important role in arrhythmogenesis.

Milrinone Dosing Issues in Critically Ill Children With Kidney Injury: A Review

Milrinone is an inotropic drug used in a variety of clinical settings in adults and children. The efficacy of milrinone in pediatric low-cardiac output syndrome after cardiac surgery is reported. Its primary route of removal from the body is through the kidney as unchanged drug in the urine. Milrinone is not known to be efficiently removed by extracorporeal dialytic therapies and thus has the potential to cause serious adverse effects and potentially worsens renal function in patients experiencing acute kidney injury (AKI). AKI is an important public health issue that is associated with increased morbidity, mortality, and cost. It is a known risk factor for the development of chronic kidney disease. There are no specific therapies to mitigate AKI once it has developed, and interventions are focused on supportive care and dose adjustment of medications. Estimating glomerular filtration rate based on height and serum creatinine is the most commonly used clinical method for assessing kidney function and modification of medication doses. The purpose of this review is to discuss our current understanding of milrinone pharmacokinetics and pharmacodynamics in children with AKI and to describe the potential use of urinary biomarkers to guide therapeutic decision making for milrinone dosing.

Syndromes of Acute Left Ventricular Failure

The syndrome of acute left ventricular failure, manifesting as pulmonary edema and/or cardiogenic shock, occurs in many different clinical settings, has many different causes, and variable treatment strategies. Most commonly it is seen as a complication of acute myocardial infarction where loss of myocardial tissue results in ineffective systolic performance of the left ventricle. Urgent percutaneous transluminal coronary angioplasty may have a significant impact on outcome in this setting. Other complicating events following myocardial infarction may also precipitate left ventricular failure including papillary muscle dysfunction and ventricular septal defect. The syndrome of acute left ventricular failure is also commonly seen in patients with chronic congestive cardiac failure whereby myocardial infarction, arrhythmia and even minor increases in salt intake can precipitate acute decompensation. Other conditions such as fulminant myocarditis, bacterial endocarditis and disease processes characterized by diastolic dysfunction can all cause acute left ventricular failure. Moreover, cardiac function may be depressed in septic shock by the presence of cardiodepressant factors. In summary, acute left ventricular failure is a syndrome with a diverse etiology. Specific diagnosis of the particular cause is crucial to appropriate management.

SERCA2a gene therapy in heart failure: an anti-arrhythmic positive inotrope

Therapeutic options that directly enhance cardiomyocyte contractility in chronic heart failure (HF) therapy are currently limited and do not improve prognosis. In fact, most positive inotropic agents, such as β-adrenoreceptor agonists and PDE inhibitors, which have been assessed in HF patients, cause increased mortality as a result of arrhythmia and sudden cardiac death. Cardiac sarcoplasmic reticulum Ca(2)(+) -ATPase2a (SERCA2a) is a key protein involved in sequestration of Ca(2)(+) into the sarcoplasmic reticulum (SR) during diastole. There is a reduction of SERCA2a protein level and function in HF, which has been successfully targeted via viral transfection of the SERCA2a gene into cardiac tissue in vivo. This has enhanced cardiac contractility and reduced mortality in several preclinical models of HF. Theoretical concerns have been raised regarding the possibility of arrhythmogenic adverse effects of SERCA2a gene therapy due to enhanced SR Ca(2)(+) load and induction of SR Ca(2)(+) leak as a result. Contrary to these concerns, SERCA2a gene therapy in a wide variety of preclinical models, including acute ischaemia/reperfusion, chronic pressure overload and chronic myocardial infarction, has resulted in a reduction in ventricular arrhythmias. The potential mechanisms for this unexpected beneficial effect, as well as mechanisms of enhancement of cardiac contractile function, are reviewed in this article.

Synthesis, biological evaluation, and pharmacokinetic study of novel liguzinediol prodrugs

Liguzinediol (LZDO) ester prodrugs 3-5 were synthesized and evaluated in vitro and in vivo for their potential use in prolonging the half-life of the parent drug LZDO (1a) in vivo. Prodrugs 3-5 were found to display a potent positive inotropic effect on the myocardium, without the risk of arrhythmia. Prodrugs 3-5 rapidly underwent enzymatic hydrolysis to release the parent compound LZDO in 1-3 h in rat liver microsomes and rat plasma. The half-life of the parent compound was prolonged after intragastric administration of prodrug 3, which was found to be a superior prodrug candidate for increasing myocardial contractility.

Narrative review: the management of acute decompensated heart failure

Acute decompensated heart failure (ADHF) is the most common reason for hospitalization in Western nations. The prognosis of patients admitted to hospital with ADHF is poor, with up to 64% being readmitted within the first 90 days after discharge and with a 1-year mortality approximating 20%. Epidemiological studies suggest that the majority of patients hospitalized with ADHF receive treatment that is inadequate and which is not based on scientific evidence. Furthermore, emerging data suggest that the "conventional" therapeutic interventions for ADHF including morphine, high-dose diuretics, and inotropic agents may be harmful. The goal of this review is to provide evidence-based recommendations for the diagnosis and management of ADHF.

Dobutamine-norepinephrine, but not vasopressin, restores the ventriculoarterial matching in experimental cardiogenic shock

We assessed the hemodynamic effects of guideline therapy in experimental cardiogenic shock and compared this treatment with a combination containing an alternative vasopressor (arginine vasopressin, AVP). Our hypothesis was that combined dobutamine-norepinephrine still is the superior inopressor therapy assessed by ventriculoarterial matching in both systole and diastole. Cardiogenic shock (CS) was induced by coronary microembolization in 16 pigs. Dobutamine (Dobu, 2ug/kg/min) alone and combined with either norepinephrine (NE, 100 ng/kg/min) or the pure vasopressor AVP (0.001 u/kg/min) were infused. In CS, Dobu increased cardiac output (CO) and central venous oxygen saturation (SVO₂) from 74 ± 3 mL/kg and 37 ± 2% to 103 ± 8 mL/kg and 49 ± 3%. Adding NE resulted in a further improvement of CO (125 ± 9 mL/kg) and SVO₂ (59 ± 4%) because of an increased heart rate and contractility with minimal change in systemic vascular resistance. Also, energy transfer from the ventricle to the arterial system was restored partly by Dobu and was normalized by supplementing NE. In contrast, supplemental AVP further worsened the shock state by decreasing CO (70 ± 6 mL/kg) and SVO₂ (45 ± 5%) compared with Dobu alone. Combined Dobu-NE has an efficient hemodynamic profile in CS. A pure afterload increasing substance used in acute ischemic CS aggravates the shock state by causing a ventriculoarterial mismatch despite its use in combination with an inotropic compound.

The usefulness of chronic heart failure treatments in chronic cardiac graft failure

Following cardiac transplantation, registry data has demonstrated a gradual improvement in survival over the last several decades, which is testament to continual improvement in aftercare strategy. However, a significant number of patients will eventually develop a new syndrome of chronic heart failure, owing to the multitude of physiological processes that occur after transplantation. This condition, referred to as chronic graft failure (CGF) should be regarded as a unique illness rather than one that is simply analogous with chronic heart failure. In particular, the unique pathophysiological (and pharmacological) environment in the setting of CGF presents a challenging situation to the transplant physician. There is uncertainty over which treatments to offer given a paucity of clinical trial data to support the use of standard heart failure treatments in CGF. In this review, we discuss which chronic heart failure treatments could be considered in the setting of CGF based on their mechanisms of action, benefits within the native heart failure setting, and the relevant issues within the posttransplant environment.

The sympathetic nervous system in heart failure physiology, pathophysiology, and clinical implications

Heart failure is a syndrome characterized initially by left ventricular dysfunction that triggers countermeasures aimed to restore cardiac output. These responses are compensatory at first but eventually become part of the disease process itself leading to further worsening cardiac function. Among these responses is the activation of the sympathetic nervous system (SNS) that provides inotropic support to the failing heart increasing stroke volume, and peripheral vasoconstriction to maintain mean arterial perfusion pressure, but eventually accelerates disease progression affecting survival. Activation of SNS has been attributed to withdrawal of normal restraining influences and enhancement of excitatory inputs including changes in: 1) peripheral baroreceptor and chemoreceptor reflexes; 2) chemical mediators that control sympathetic outflow; and 3) central integratory sites. The interface between the sympathetic fibers and the cardiovascular system is formed by the adrenergic receptors (ARs). Dysregulation of cardiac beta(1)-AR signaling and transduction are key features of heart failure progression. In contrast, cardiac beta(2)-ARs and alpha(1)-ARs may function in a compensatory fashion to maintain cardiac inotropy. Adrenergic receptor polymorphisms may have an impact on the adaptive mechanisms, susceptibilities, and pharmacological responses of SNS. The beta-AR blockers and the inhibitors of the renin-angiotensin-aldosterone axis form the mainstay of current medical management of chronic heart failure. Conversely, central sympatholytics have proved harmful, whereas sympathomimetic inotropes are still used in selected patients with hemodynamic instability. This review summarizes the changes in SNS in heart failure and examines how modulation of SNS activity may affect morbidity and mortality from this syndrome.

Tolerance development as a pharmacological and clinical problem

Two main forms of acquired pharmacological tolerance may be distinguished, dispositional (pharmacokinetic) and pharmacodynamic. Pharmacodynamic tolerance is common, and can in many cases be attributed to adaptive receptor changes. Such changes of beta-adrenoceptors have been extensively studied and widely used as models for explaining the mechanisms of tolerance development. The mechanisms behind tolerance to adrenoceptor agonists are discussed, and also tolerance development to these and some other agents when used in the treatment of asthma, uterine hyperactivity and congestive heart failure.

Inotropic drugs and neurohormonal antagonists in the treatment of HF in the elderly

Heart failure (HF) is the most common reason for hospital admission among individuals over age 65 years and results in more than 1 million admissions each year. The overall annual death rate for HF is approximately 20%. HF results from decreased contractile function of the heart, and neurohormonal dysregulation plays a major part in the morbidity and mortality of the heart. The purpose of this article is to review recent studies on inotropic drugs and neurohormonal antagonists used in the treatment of patients who have HF, especially the elderly.

Classical inotropes and new cardiac enhancers

Acute heat failure syndromes are a heterogenous group of conditions. Chronic heart failure exacerbations represent the vast majority of cases. Pathophysiologic mechanisms, such as hypotension with peripheral tissue hypoperfusion, renal function impairment and myocardial ischemia and injury, adversely affect patients' clinical outcome. Classical inotropes, such as beta-agonists (dobutamine, dopamine) and phosphodiesterase inhibitors (milrinone), seem to improve clinical symptoms and hemodynamics of acutely decompensated chronic heat failure patients, but they have been associated with increased long-term mortality. Thus, on the basis of the available evidence, these agents can be used only as a temporary treatment of acute heart failure exacerbations with stringent criteria (ESC AHF guidelines), resistant to intravenous vasodilators and/or diuretics when systolic blood pressure (SBP) is >100 mmHg or as a first-line treatment in patients with worsening of chronic cardiac failure and low SBP (<100 mmHg). The calcium sensitizer levosimendan is a new cardiac enhancer that seems to be more effective than classical inotropes in improving cardiac mechanical efficiency and reducing congestion, without causing cardiomyocyte death or increasing myocardial oxygen uptake. Recent randomized trials showed that levosimendan is not superior to placebo or dobutamine in improving 1- and 6-month mortality, although it caused a greater reduction of neurohormonal response. More data are needed regarding patient selection and the optimum regimen and dosing of levosimendan before this treatment modality become the first line therapy of acutely decompensated chronic heart failure patients.

Inotropic drugs and neurohormonal antagonists in the treatment of HF in the elderly

HF (HF) is the most common reason for hospital admission among individuals over age 65 years and results in more than 1 million admissions each year. The overall annual death rate for HF is approximately 20%. HF results from decreased contractile function of the heart, and neurohormonal dysregulation plays a major part in the morbidity and mortality of the heart. The purpose of this article is to review recent studies on inotropic drugs and neurohormonal antagonists used in the treatment of patients who have HF, especially the elderly.

The Effects of Continuous Positive Airway Pressure on Myocardial Energetics in Patients With Heart Failure and Obstructive Sleep Apnea

OBJECTIVES

We sought to examine the short-term and longer term (6-week) effects of continuous positive airway pressure (CPAP) on myocardial energetics.

BACKGROUND

Obstructive sleep apnea (OSA) and heart failure (HF) are both states of increased afterload and metabolic demand. Treatment with CPAP may initially reduce stroke volume but subsequently improves left ventricular function. However, it is not clear whether CPAP therapy favorably affects myocardial energetics and hence improves cardiac efficiency.

METHODS

Twelve patients with HF were divided into two groups: 7 patients with OSA were treated with CPAP (group I), and 5 patients without OSA served as a control group (group II). Oxidative metabolism was measured using the mono-exponential fit of the myocardial [(11)C] acetate positron emission tomography time-activity curve (k-mono). Myocardial efficiency was derived using the work metabolic index (WMI = [heart rate x stroke volume index x systolic blood pressure]/k-mono) measured at baseline, during short-term CPAP, and after 6 +/- 3 weeks of CPAP.

RESULTS

In group I, short-term CPAP tended to reduce SVI (p = 0.063) and reduced oxidative metabolism (p = 0.031). Work metabolic index did not change. However, longer term CPAP improved left ventricular ejection fraction (38.4 +/- 3.3% to 43.4 +/- 4.8%, p = 0.031), tended to reduce oxidative metabolism (0.047 +/- 0.012 to 0.040 +/- 0.008 min(-1), p = 0.078), and improved WMI (7.13 +/- 2.82 x 10(6) to 8.17 +/- 3.06 x 10(6) mm Hg.ml/m(2), p = 0.031). In group II (control), these parameters did not change.

CONCLUSIONS

In this cohort of patients with HF and OSA, short-term CPAP decreased oxidative metabolism and tended to decrease SVI, but did not alter cardiac efficiency. Longer term CPAP improved cardiac efficiency, indicating an energy-sparing effect. These effects may contribute to the benefits of CPAP therapy.

Reassessment of dobutamine, dopamine, and milrinone in the management of acute heart failure syndromes

The appropriate role of intravenous inodilator therapy (inotropic agents with vasodilator properties) in the management of acute heart failure syndromes (AHFS) has long been a subject of controversy, mainly because of the lack of prospective, placebo-controlled trials and a lack of alternative therapies. The use of intravenous inodilator infusions, however, remains common, but highly variable. As new options emerge for the treatment of AHFS, the available information should be reviewed to determine which approaches are supported by evidence, which are used empirically without evidence, and which should be considered inappropriate. For these purposes, we reviewed data available from randomized controlled trials on short-term, intermittent, and long-term use of intravenous inodilator agents (dobutamine, dopamine, and milrinone) in AHFS. Randomized controlled trials failed to show benefits with current medications and suggested that acute, intermittent, or continuous use of inodilator infusions may increase morbidity and mortality in patients with AHFS. Their use should be restricted to patients who are hypotensive as a result of low cardiac output despite a high left ventricular filling pressure.

Phosphodiesterase III inhibitors for heart failure

BACKGROUND

In the treatment of chronic heart failure, vasodilating agents, ACE inhibitors and beta-blockers have shown an increase of life expectancy. Another strategy is to increase the inotropic state of the myocardium : phosphodiesterase inhibitors (PDIs) act by increasing intra-cellular cyclic AMP, thereby increasing the concentration of intracellular calcium, and lead to a positive inotropic effect.

OBJECTIVES

This overview on summarised data aims to review the data from all randomised controlled trials of PDIs III versus placebo in symptomatic patients with chronic heart failure. The primary endpoint is total mortality. Secondary endpoints are considered such as cause-specific mortality, worsening of heart failure (requiring intervention), myocardial infarction, arrhythmias and vertigos. We also examine whether the therapeutic effect is consistent in the subgroups based on the use of concomitant vasodilators, the severity of heart failure, and the type of PDI derivative and/or molecule. This overview updates our previous meta-analysis published in 1994.

SEARCH STRATEGY

Randomised trials of PDIs versus placebo in heart failure were searched using MEDLINE (1966 to 2004 January), EMBASE (1980 to 2003 December), Cochrane CENTRAL trials (The Cochrane Library Issue 1, 2004) and McMaster CVD trials registries, and through an exhaustive handsearching of international abstracting publications (abstracts published in the last 22 years in the "European Heart Journal", the "Journal of the American College of Cardiology" and "Circulation").

SELECTION CRITERIA

All randomised controlled trials of PDIs versus placebo with a follow-up duration of more than three months.

DATA COLLECTION AND ANALYSIS

21 trials (8408 patients) were eligible for inclusion in the review. 4 specific PDI derivatives and 8 molecules of PDIs have been considered.

MAIN RESULTS

As compared with placebo, treatment with PDIs was found to be associated with a significant 17% increased mortality rate (The relative risk was 1.17 (95% confidence interval 1.06 to 1.30; p<0.001). In addition, PDIs significantly increase cardiac death, sudden death, arrhythmias and vertigos. Considering mortality from all causes, the deleterious effect of PDIs appears homogeneous whatever the concomitant use (or non-use) of vasodilating agents, the severity of heart failure, the derivative or the molecule of PDI used.

AUTHORS' CONCLUSIONS

Our results confirm that PDIs are responsible for an increase in mortality rate compared with placebo in patients suffering from chronic heart failure. Currently available results do not support the hypothesis that the increased mortality rate is due to additional vasodilator treatment. Consequently, the chronic use of PDIs should be avoided in heart failure patients.

Effect of levosimendan on balance between ATP production and consumption in isolated perfused guinea-pig heart before ischemia or after reperfusion

Levosimendan is a novel drug developed for treatment of decompensated heart failure. Levosimendan is a calcium sensitizer that increases contractile force of the myocardium by enhancing the sensitivity of myofilaments to calcium without increasing intracellular calcium concentration. The present study was carried out to investigate whether levosimendan induces any changes in the phosphorylation potential (ie, the balance between ATP production and consumption) in the normal heart and in the post-ischemic heart while exerting its positive inotropic effect. We show that 0.1 microM levosimendan increased the left ventricle developed pressure in the pre-ischemic and in the post ischemic hearts by 16 and 18% respectively, and the +dP/dt by 16 and 19%, respectively. At that concentration levosimendan did not cause any effect on the phosphorylation potential (1 x 10(5) M(-1) and 0.2 x 10(5) M(-1) in the pre-ischemic and post-ischemic heart, respectively) as assessed by P-NMR, although an increased beating rate (13%) and oxygen consumption (10%) was observed when adding the drug post-ischemically. Our findings are consistent with the results of a recent clinical trial (RUSSLAN), which showed that levosimendan does not induce ischemia and reduces the risk of worsening heart failure and death, in patients with left ventricular failure complicating acute myocardial infarction.

Optimising outcomes in end-stage heart failure: differences in therapeutic responses between diverse ethnic groups

Clinical and pathophysiological differences between Japanese and Caucasian patients are observed in many aspects of heart disease. Indeed, data derived from studies in one population cannot be automatically extrapolated to the other. The therapeutic goal of heart failure has recently been aimed at improving mortality in Western societies. The long-term use of an inotropic agent in the energy-starved failing heart has been expected to increase myocardial energy use and accelerate the disease process. However, this may not be the case in the Japanese population in whom mortality is relatively low. Therefore, vesnarinone therapy could be justified, since it allows optimal care in terms of an improved quality of life. Nevertheless, re-analysis of the findings of the Vesnarinone Trial (VEST) emphasised again the reasons for the precautions relating to vesnarinone use: (i) vesnarinone was associated with increased death, usually occurring within 7 months of initiation of the drug; (ii) the mortality rate was higher in patients receiving concomitant digoxin, which necessitated close monitoring of renal function; (iii) the mortality rate also increased in patients with severe bradycardia, indicating the importance of regular ECG monitoring; and (iv) improvements in cardiac function and symptoms by the drug may result in sudden death, particularly in patients with severe heart failure. Such patients should be closely monitored by a physician.

The Evolving Role of Nesiritide in Advanced or Decompensated Heart Failure

Nesiritide is a recombinant form of human brain natriuretic peptide (BNP) that is structurally and biochemically identical to endogenously produced BNP. In humans, BNP is important in hemodynamic and neurohormonal equilibrium, helping to maintain adequate vascular volume and pressure in response to volume overload. The pharmacodynamic effects of nesiritide mimic the biologic effects of BNP. The molecular biology and actions of nesiritide and BNP are reviewed, with the therapeutic rationale for nesiritide in patients with acute or advanced decompensated heart failure highlighted. In addition, recommendations for its administration are provided, and unresolved therapeutic considerations are discussed.

Role of nonglycosidic inotropic agents: indications, ethics, and limitations

Nonglycosidic inotropic agents have been used for the short-term management of low output states and hypotension complicating acute myocardial infarction for several years. Without adequate reperfusion of the ischemic myocardium, inotropic agents are seldom effective in producing sustained hemodynamic responses. Furthermore, the potential exists for enhancement of ischemia and extension of myocardial necrosis. Thus, inotropic and vasopressors therapy should be regarded as temporary supportive treatment in patients with acute coronary syndrome and should be discontinued as soon as feasible. Parenteral sympathomimetic agents, usually dobutamine, and phosphodiesterase inhibitors, usually milrinone, are used for the management of exacerbations of chronic systolic heart failure. Although hemodynamics, and occasionally clinical status, improve, such therapy is associated with increased mortality and can potentially hasten a patient's demise. Nonparenteral sympathomimetics, such as ibopamine, phosphodiesterase-III inhibitors, such as milrinone and enoximone, calcium-sensitizing agents, such as pimobendan, and other novel inotropic agents, such as vesnarinone, all increase mortality of patients with chronic heart failure. Furthermore, newer noninotropic agents, such as B-natriuretic peptide, have been introduced for treatment of decompensated heart failure. New nonpharmacologic devices, such as biventricular pacing, are available for the treatment of advanced heart failure. Thus, indications for the use of presently available nonglycosidic inotropic agents are limited and should be considered only for short-term therapy or when no other treatment is available.

Pharmacotherapeutic approaches for decompensated heart failure: a role for the calcium sensitiser, levosimendan?

Although no universal definition exists, decompensated heart failure may be regarded as either a worsening of chronic heart failure or new-onset heart failure precipitated by an acute incident. Haemodynamic management of patients hospitalised with decompensated heart failure may include the administration of diuretics, vasodilators and positive inotropic agents. Until recently, these latter agents constituted the only drug class to produce a direct increase in stroke volume via enhanced myocardial contractility. However, despite their short-term benefits, the clinical utility of inotropic agents is compromised by their potentially deleterious effects on calcium handling and oxygen consumption, resulting in an increased risk of serious ventricular arrhythmias and death. In contrast, calcium sensitisers enhance cardiac performance without affecting calcium movement and, therefore, are potentially associated with a reduced risk of rhythmic disturbances. These agents constitute a heterogeneous group of compounds with different affinities for calcium sensitisation. Levosimendan is a potent calcium sensitiser with vasodilating properties that has been shown to provide symptomatic and haemodynamic improvement with no increase in oxygen consumption. Calcium sensitisation is therefore emerging as a promising treatment approach in this challenging therapeutic area.

Inotropic therapy for heart failure: an evidence-based approach

BACKGROUND

Agents that increase cardiac contractility (positive inotropes) have beneficial hemodynamic effects in patients with acute and chronic heart failure but have frequently led to increased mortality when given on a long-term basis. Despite this fact, inotropes remain commonly used in the management of heart failure.

METHODS

We reviewed the available data on short- and long-term inotrope use in heart failure, emphasizing high-quality evidence on the basis of randomized trials that were powered to address clinical end points.

RESULTS

Available data suggest that long-term inotropic therapy has a negative impact on survival in patients with heart failure, regardless of the agent used. The data that inotropic therapy improves quality of life are mixed. High-quality randomized evidence is lacking for the use of inotropes for other heart failure indications, such as for acute decompensations or as a "bridge to transplant."

CONCLUSIONS

On the basis of the available evidence, the routine use of inotropes as heart failure therapy is not indicated in either the acute or chronic setting. Potentially appropriate uses of inotropes include as temporary treatment of diuretic-refractory acute heart failure decompensations or as a bridge to definitive treatment such as revascularization or cardiac transplantation. Inotropes also may be appropriate as a palliative measure in patients with truly end-stage heart failure. A model of heart failure pathophysiologic features that combines an understanding of both hemodynamic and neurohormonal factors will be required to best develop and evaluate novel treatments for advanced heart failure.

Comparison of the occurrence of ventricular arrhythmias in patients with acutely decompensated congestive heart failure receiving dobutamine versus nesiritide therapy

Ventricular arrhythmias are common in patients with congestive heart failure (CHF) and may be exacerbated by positive inotropic therapy. Because human B-type natriuretic peptide (nesiritide), an arterial and venodilator, inhibits sympathetic activity, it may decrease the incidence of arrhythmias. Our investigation compares the arrhythmogenicity of dobutamine with nesiritide. A total of 305 patients with decompensated CHF requiring intravenous vasoactive therapy were randomized to receive standard therapy (n = 102) or nesiritide (0.015 microg/kg/min [n = 103] or 0.030 microg/kg/min [n = 100]) to gain additional data on the relative safety and efficacy of nesiritide compared with standard parenteral care. Dobutamine was chosen as the standard care agent in 58 subjects. During study drug infusion, all patients had continuous clinical hemodynamic and electrocardiographic monitoring. The dobutamine and nesiritide groups were similar with respect to baseline use of antiarrhythmic agents, including beta blockers. Serious arrhythmias and the incidence of cardiac arrest were more common in patients who received dobutamine than in those taking nesiritide: sustained ventricular tachycardia, 4 (7%) versus 2 (1%), respectively (p = 0.014); nonsustained ventricular tachycardia, 10 (17%) versus 23 (11%), respectively (p = 0.029); cardiac arrest, 3 (5%) versus 0, respectively (p = 0.011). We conclude that among patients with decompensated CHF for whom dobutamine is selected as standard therapy, the incidence of serious ventricular arrhythmias and cardiac arrest is significantly greater than the incidence of these events in patients randomized to nesiritide.

Low-dose enoximone improves exercise capacity in chronic heart failure. Enoximone Study Group

OBJECTIVES

This study was designed to evaluate the effects of low-dose enoximone on exercise capacity.

BACKGROUND

At higher doses the phosphodiesterase inhibitor, enoximone, has been shown to increase exercise capacity and decrease symptoms in heart failure patients but also to increase mortality. The effects of lower doses of enoximone on exercise capacity and adverse events have not been evaluated.

METHODS

This is a prospective, double-blind, placebo-controlled, multicenter trial (nine U.S. centers) conducted in 105 patients with New York Heart Association class II to III, ischemic or nonischemic chronic heart failure (CHF). Patients were randomized to placebo or enoximone at 25 or 50 mg orally three times a day. Treadmill maximal exercise testing was done at baseline and after 4, 8 and 12 weeks of treatment, using a modified Naughton protocol. Patients were also evaluated for changes in quality of life and for increased arrhythmias by Holter monitoring.

RESULTS

By the protocol-specified method of statistical analysis (the last observation carried-forward method), enoximone at 50 mg three times a day improved exercise capacity by 117 s at 12 weeks (p = 0.003). Enoximone at 25 mg three times a day also improved exercise capacity at 12 weeks by 115 s (p = 0.013). No increases in ventricular arrhythmias were noted. There were four deaths in the placebo group and 2 and 0 deaths in the enoximone 25 mg three times a day and enoximone 50 mg three times a day groups, respectively. Effects on degree of dyspnea and patient and physician assessments of clinical status favored the enoximone groups.

CONCLUSIONS

Twelve weeks of treatment with low-dose enoximone improves exercise capacity in patients with CHF, without increasing adverse events.

Prophylactic amrinone for weaning from cardiopulmonary bypass

This prospective, randomised, double-blind, controlled clinical study was performed at a single tertiary referral centre to test the hypothesis that the prophylactic administration of amrinone before separation of a patient from cardiopulmonary bypass decreases the incidence of failure to wean, and to identify those patients who could be predicted to benefit from such pre-emptive management. Two hundred and thirty-four patients, scheduled to undergo elective cardiac surgery, were randomly allocated to receive either a bolus dose of 1.5 mg x kg(-1) amrinone over 15 min, followed by an infusion of 10 microg x kg(-1) x min(-1), or a bolus of placebo of equal volume followed by an infusion of placebo. Treatment with amrinone or placebo was initiated upon release of the aortic cross-clamp, before weaning from cardiopulmonary bypass. Anaesthetic technique, monitoring and myocardial preservation methods were standardised for both groups. Significantly fewer patients failed to wean in the group that received prophylactic amrinone than in the control group (7 vs. 21%, p = 0.002). Amrinone improved weaning success regardless of left ventricular ejection fraction, although this benefit was statistically significant only in the group with left ventricular ejection fractions > 55%. Of the 32 patients who failed to wean from cardiopulmonary bypass, 14 had normal pre-operative left ventricular ejection fractions.

Electropharmacological effects of UK-1745, a novel cardiotonic drug, in guinea-pig ventricular myocytes

Effects of (2RS, 3SR)-2-aminomethyl-2,3,7,8-tetrahydro-2,3,5,8, 8-pentamethyl-6H-furo-[2,3-e] indol-7-one hydrochloride (UK-1745), a novel cardiotonic drug with beta-adrenoceptor blocking property and antiarrhythmic activity, on the action potentials of isolated papillary muscles and the membrane currents of single ventricular myocytes of guinea pigs were examined and compared with those of milrinone using conventional microelectrode and patch-clamp techniques. In papillary muscles, UK-1745 (3-100 microM) produced a mild positive inotropic response and depressed the maximum upstroke velocity of the action potential (V(max)) at 100 microM. Milrinone, a phosphodiesterase III inhibitor, markedly shortened the action potential duration with a significant increase in developed tension. In enzymatically-dissociated ventricular myocytes, UK-1745 failed to increase the L-type Ca(2+) current (I(Ca)) at 10 and 30 microM and rather decreased I(Ca) at 100 microM. The high concentration of UK-1745 slightly inhibited the delayed rectifier K(+) current (I(K)). Although UK-1745 antagonized the isoproterenol-induced increase in I(Ca), it potentiated the histamine-induced increase in I(Ca). On the other hand, milrinone per se significantly increased I(Ca) and markedly enhanced the isoproterenol-induced increase in I(Ca). It can be concluded that UK-1745 is a unique cardiotonic drug possessing beta-adrenoceptor blocking and weak phosphodiesterase-inhibitory actions in addition to direct inhibitory actions on the Na(+), Ca(2+) and K(+) channels with its high concentrations.

Tolerability of extended duration intravenous milrinone in patients hospitalized for advanced heart failure and the usefulness of uptitration of oral angiotensin-converting enzyme inhibitors

Milrinone is a phosphodiesterase inhibitor that has been shown to improve hemodynamic parameters in patients with class III to IV heart failure when administered intravenously for < or =48 hours. This study examines the tolerability of long-term intravenous milrinone therapy and assesses its utility in allowing upward titration of oral vasodilator agents. A retrospective review of hospital records identified 63 patients who underwent hemodynamic monitoring and received intravenous milrinone for >24 hours in a critical care setting. Hemodynamics and medications were recorded before and after 24 hours of milrinone therapy. Additional medications, as well as any adverse events, were recorded throughout milrinone therapy. The mean dose of milrinone was 0.43 +/- 0.10 microg/kg/min, with a mean duration of 12 +/- 15 days (range 1 to 70). Therapy was continued for >48 hours in 89% of patients. After 24 hours of milrinone therapy, patients exhibited significant improvements in pulmonary artery pressures, pulmonary capillary wedge pressures, and cardiac index. When compared with baseline, significantly more patients received angiotensin-converting enzyme (ACE) inhibitors after 24 hours of milrinone and at the end of milrinone therapy (67% vs 86%, p <0.01). Likewise, significantly more patients also received oral hydralazine and/or nitrates at the end of milrinone therapy (38% vs 65%, p <0.01) when compared with baseline. The mean doses of most oral medications at the 3 time periods were similar. The ACE inhibitor dose was significantly higher at the end of milrinone therapy when compared with baseline, and hydralazine dose was significantly higher at the end of therapy when compared with 24 hours. Few adverse effects were noted, with only 10% of patients experiencing symptomatic ventricular tachycardia and 2 patients with significant hypotension requiring discontinuation of the drug. The adverse events were similar in the group of patients who received milrinone for > or =7 days compared with the entire cohort. Milrinone was well tolerated over the long term in a controlled inpatient setting, and allowed uptitration of oral vasodilator therapy.

Symptomatic systolic ventricular failure

Over the past 20 to 30 years there have been significant advances in the management of heart failure related to improved understanding of pathophysiology, better methods of assessment, and improved drug treatments. The aims of treatment have broadened, with increased emphasis on earlier intervention. Clinical research activity in this area has been considerable, increasingly allowing an evidence-based approach to management. Most earlier trials of treatment were relatively short-term, small-group studies with various clinical end points, including severity of symptoms, exercise performance, and left ventricular function assessment; however, increasingly a higher standard of evidence has been required, including a provision of reliable, large-scale mortality trial data. This has been further encouraged, if not mandated, by the relatively recent appreciation that some agents may demonstrate dissociation of treatment effects, possibly dose related, with improved short-term outcomes but adverse effects on survival with prolonged treatment. The general principles of management of congestive heart failure encompass patient evaluation and confirmation of the diagnosis, consideration, and correction of underlying remediable causes and precipitating factors, pharmacological treatment, patient education and counseling, and planned follow-up, as summarized in recently published guidelines. This review focuses primarily on the available randomized controlled clinical trial evidence related to the pharmacological treatment of the clinical congestive heart failure syndrome. Other aspects of management, such as patient education, counseling, and planned follow-up, should be regarded as complementary to pharmacological treatment and important to ensure compliance and optimal long-term outcomes.