Combined oral positive inotropic and beta-blocker therapy for treatment of refractory class IV heart failure

Phosphodiesterase in heart and vessels: from physiology to diseases

Phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyze cyclic nucleotides, including cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Both cyclic nucleotides are critical secondary messengers in the neurohormonal regulation in the cardiovascular system. PDEs precisely control spatiotemporal subcellular distribution of cyclic nucleotides in a cell- and tissue-specific manner, playing critical roles in physiological responses to hormone stimulation in the heart and vessels. Dysregulation of PDEs has been linked to the development of several cardiovascular diseases, such as hypertension, aneurysm, atherosclerosis, arrhythmia, and heart failure. Targeting these enzymes has been proven effective in treating cardiovascular diseases and is an attractive and promising strategy for the development of new drugs. In this review, we discuss the current understanding of the complex regulation of PDE isoforms in cardiovascular function, highlighting the divergent and even opposing roles of PDE isoforms in different pathogenesis.

Beta-blocker management in patients admitted for acute heart failure and reduced ejection fraction: a review and expert consensus opinion

The role of the beta-adrenergic signaling pathway in heart failure (HF) is pivotal. Early blockade of this pathway with beta-blocker (BB) therapy is recommended as the first-line medication for patients with HF and reduced ejection fraction (HFrEF). Conversely, in patients with severe acute HF (AHF), including those with resolved cardiogenic shock (CS), BB initiation can be hazardous. There are very few data on the management of BB in these situations. The present expert consensus aims to review all published data on the use of BB in patients with severe decompensated AHF, with or without hemodynamic compromise, and proposes an expert-recommended practical algorithm for the prescription and monitoring of BB therapy in critical settings.

Beta-blockers and Ambulatory Inotropic Therapy

BACKGROUND

Continuous infusion of ambulatory inotropic therapy (AIT) is increasingly used in patients with end-stage heart failure (HF). There is a paucity of data concerning the concomitant use of beta-blockers (BB) in these patients.

METHODS

We retrospectively reviewed all patients discharged from our institution on AIT. The cohort was stratified into 2 groups based on BB use. The 2 groups were compared for differences in hospitalizations due to HF, ventricular arrhythmias and ICD therapies (shock or antitachycardia pacing).

RESULTS

Between 2010 and 2017, 349 patients were discharged on AIT (95% on milrinone); 74% were males with a mean age of 61 ± 14 years. BB were used in 195 (56%) patients, whereas 154 (44%) did not receive these medications. Patients in the BB group had longer duration of AIT support compared to those in the non-BB group (141 [1-2114] vs 68 [1-690] days). After adjusting for differences in baseline characteristics and indication for AIT, patients in the BB group had significantly lower rates of hospitalizations due to HF (hazard ratio [HR] 0.61 (0.43-0.86); P = 0.005), ventricular arrhythmias (HR 0.34 [0.15-0.74]; P = 0.007) and ICD therapies (HR 0.24 [0.07-0.79]; P = 0.02).

CONCLUSION

In patients with end-stage HF on AIT, the use of BB with inotropes was associated with fewer hospitalizations due to HF and fewer ventricular arrhythmias.

A Review of Inotropes and Inopressors for Effective Utilization in Patients With Acute Decompensated Heart Failure

ABSTRACT

Inotropes and inopressors are often first-line treatment in patients with cardiogenic shock. We summarize the pharmacology, indications, and contraindications of dobutamine, milrinone, dopamine, norepinephrine, epinephrine, and levosimendan. We also review the data on the use of these medications for acute decompensated heart failure and cardiogenic shock in this article.

Myocardial Phosphodiesterases and Their Role in cGMP Regulation

Cyclic nucleotide phosphodiesterases comprise an 11-member superfamily yielding near 100 isoform variants that hydrolyze cAMP or cGMP to their respective 5'-monophosphate form. Each plays a role in compartmentalized cyclic nucleotide signaling, with varying selectivity for each substrate, and conveying cell and intracellular-specific localized control. This review focuses on the 5 phosphodiesterases (PDEs) expressed in the cardiac myocyte capable of hydrolyzing cGMP and that have been shown to play a role in cardiac physiological and pathological processes. PDE1, PDE2, and PDE3 catabolize cAMP as well, whereas PDE5 and PDE9 are cGMP selective. PDE3 and PDE5 are already in clinical use, the former for heart failure, and PDE1, PDE9, and PDE5 are all being actively studied for this indication in patients. Research in just the past few years has revealed many novel cardiac influences of each isoform, expanding the therapeutic potential from their selective pharmacological blockade or in some instances, activation. PDE1C inhibition was found to confer cell survival protection and enhance cardiac contractility, whereas PDE2 inhibition or activation induces beneficial effects in hypertrophied or failing hearts, respectively. PDE3 inhibition is already clinically used to treat acute decompensated heart failure, although toxicity has precluded its long-term use. However, newer approaches including isoform-specific allosteric modulation may change this. Finally, inhibition of PDE5A and PDE9A counter pathological remodeling of the heart and are both being pursued in clinical trials. Here, we discuss recent research advances in each of these PDEs, their impact on the myocardium, and cardiac therapeutic potential.

Oral Enoximone as an Alternative to Protracted Intravenous Medication in Severe Pediatric Myocardial Failure

Phosphodiesterase 3 inhibitors have been used successfully in pediatric patients with acute or chronic myocardial dysfunction over the last two decades. Their protracted continuous intravenous administration is associated with risk of infectious and thromboembolic complications. Weaning intravenous medication and starting oral angiotensin-converting enzyme (ACE) inhibitors and/or beta-blockers can be challenging. We reviewed retrospectively hospital records of 48 patients receiving oral enoximone treatment in a single tertiary pediatric cardiac center between November 2005 and April 2014. Failure to wean from intravenous milrinone infusion and/or intolerance of ACE inhibitors and/or beta-blockers was indications for oral enoximone treatment. Age of the patients ranged between 0.5 and 191 months (median 7.5 months) at the time of starting enoximone treatment. There were 14 patients (29 %) with left ventricular dysfunction due to myocarditis or dilated cardiomyopathy and 34 patients (71 %) with myocardial dysfunction complicating congenital heart disease. Fifteen (44 %) of these 34 patients had left ventricular dysfunction, 13 (38 %) right ventricular dysfunction, and in 6 (18 %) both ventricles were failing. Duration of oral enoximone treatment was between 3 days and 34 months (median of 2.3 months). Myocardial functional recovery allowed for weaning of enoximone treatment in 15 patients (31 %) after 6 days-15 months (median 5 months). No adverse hemodynamic effects were noted. Blood stained gastric aspirates encountered in two patients resolved with concomitant milk administration. Based on our limited experience, oral enoximone is a well-tolerated and promising alternative to intravenous medication and/or other commonly used oral medications in selected pediatric patients with chronic heart failure.

Novel role of phosphodiesterase inhibitors in the management of end-stage heart failure

In advanced heart failure (HF), chronic inotropic therapy with intravenous milrinone, a phosphodiesterase III inhibitor, is used as a bridge to advanced management that includes transplantation, ventricular assist device implantation, or palliation. This is especially true when repeated attempts to wean off inotropic support result in symptomatic hypotension, worsened symptoms, and/or progressive organ dysfunction. Unfortunately, patients in this clinical predicament are considered hemodynamically labile and may escape the benefits of guideline-directed HF therapy. In this scenario, chronic milrinone infusion may be beneficial as a bridge to introduction of evidence based HF therapy. However, this strategy is not well studied, and in general, chronic inotropic infusion is discouraged due to potential cardiotoxicity that accelerates disease progression and proarrhythmic effects that increase sudden death. Alternatively, chronic inotropic support with milrinone infusion is a unique opportunity in advanced HF. This review discusses evidence that long-term intravenous milrinone support may allow introduction of beta blocker (BB) therapy. When used together, milrinone does not attenuate the clinical benefits of BB therapy while BB mitigates cardiotoxic effects of milrinone. In addition, BB therapy decreases the risk of adverse arrhythmias associated with milrinone. We propose that advanced HF patients who are intolerant to BB therapy may benefit from a trial of intravenous milrinone as a bridge to BB initiation. The discussed clinical scenarios demonstrate that concomitant treatment with milrinone infusion and BB therapy does not adversely impact standard HF therapy and may improve left ventricular function and morbidity associated with advanced HF.

Infections, Arrhythmias, and Hospitalizations on Home Intravenous Inotropic Therapy

Inotropes improve symptoms in advanced heart failure (HF) but were associated with higher mortality in clinical trials. Recurrent hospitalizations, arrhythmias, and infections contribute to morbidity and mortality, but the risks of these complications with modern HF therapies are not well known. We collected arrhythmia, infection, and hospitalization data on 197 patients discharged from our institution from January 2007 to March 2013 on intravenous inotropes. Patients were followed until they died, received a transplant or left ventricular assist device, were weaned off inotropes, or remained on inotropes at the end of the study. All patients had stage D HF. At baseline, 30% had a history of ventricular tachycardia, 7.1% had a history of cardiac arrest, and 39% had a history of atrial fibrillation. During follow-up, 33 patients (17%) had one or more implantable cardioverter-defibrillator shocks. Of patients who had shocks, 27 patients (82%) had appropriate shocks for ventricular tachycardia/ventricular fibrillation, 3 patients (9%) had inappropriate shocks, and 3 patients (9%) had both appropriate and inappropriate shocks. The risk of implantable cardioverter-defibrillator shock was not related to dose of inotrope (p = 0.605). Fifty-seven patients (29%) had one or more infections during follow-up. Bacteremia was the most common type of infection. Implanted electrophysiology devices did not confer an increased risk of infection. One hundred twelve patients (57%) had one or more hospitalizations during follow-up. Common causes of hospitalizations were worsening HF symptoms (41%), infections (20%), and arrhythmias (12%). In conclusion, arrhythmias, infections, and rehospitalizations are important complications of inotropic therapy.

Weaning from inotropic support and concomitant beta-blocker therapy in severely ill heart failure patients: take the time in order to improve prognosis

AIMS

Beta-blockers improve the prognosis in heart failure (HF), but their introduction may seem impossible in patients dependent on inotropic support. However, many of these patients can be titrated on beta-blockers, but there is little evidence of successful clinical strategies.

METHODS AND RESULTS

We analysed the records of inotropy-dependent patients referred for assessment for heart transplantation. Thirty-six patients (45%) could not be weaned (NW) and underwent left ventricular assist device (LVAD) implantation or transplantation, or died. However, 44 (55%) were successfully weaned (SW). Neither the aetiology (ischaemic vs. non-ischaemic) nor cardiac indexes were different in the SW as compared with the NW group (2.27±0.5 vs. 2.15±0.6 L/min/m2). The NW patients had lower LVEF (15±5% vs. 19±5%, P=0.001), higher right atrial pressure (12±6 vs. 8±6 mmHg, P=0.02), and more severe mitral regurgitation (P<0.001) than the SW patients. At discharge, 35 of 44 SW patients were receiving beta-blockers. In 29 of them, a beta-blocker could only be initiated or continued during concomitant support with i.v. enoximone for a duration of 14.1±7.2 days. Patients discharged on a beta-blocker had an LVAD/transplantation-free cumulative survival of 71% during a follow-up of 2074±201 days (confidence interval 1679–2470).

CONCLUSION

It takes time to put severely ill HF patients on beta-blockers and it may require bridging with inotropes which are independent of beta-adrenergic receptors. Whether such a strategy may result in a better clinical outcome warrants further research.

The adrenergic system in pulmonary arterial hypertension: bench to bedside (2013 Grover Conference series)

In heart failure with reduced left ventricular ejection fraction (HFrEF), adrenergic activation is a key compensatory mechanism that is a major contributor to progressive ventricular remodeling and worsening of heart failure. Targeting the increased adrenergic activation with β-adrenergic receptor blocking agents has led to the development of arguably the single most effective drug therapy for HFrEF. The pressure-overloaded and ultimately remodeled/failing right ventricle (RV) in pulmonary arterial hypertension (PAH) is also adrenergically activated, which raises the issue of whether an antiadrenergic strategy could be effectively employed in this setting. Anecdotal experience suggests that it will be challenging to administer an antiadrenergic treatment such as a β-blocking agent to patients with established moderate-severe PAH. However, the same types of data and commentary were prevalent early in the development of β-blockade for HFrEF treatment. In addition, in HFrEF approaches have been developed for delivering β-blocker therapy to patients who have extremely advanced heart failure, and these general principles could be applied to RV failure in PAH. This review examines the role played by adrenergic activation in the RV faced with PAH, contrasts PAH-RV remodeling with left ventricle remodeling in settings of sustained increases in afterload, and suggests a possible approach for safely delivering an antiadrenergic treatment to patients with RV dysfunction due to moderate-severe PAH.

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.

Phosphodiesterase type 3A regulates basal myocardial contractility through interacting with sarcoplasmic reticulum calcium ATPase type 2a signaling complexes in mouse heart

RATIONALE

cAMP is an important regulator of myocardial function, and regulation of cAMP hydrolysis by cyclic nucleotide phosphodiesterases (PDEs) is a critical determinant of the amplitude, duration, and compartmentation of cAMP-mediated signaling. The role of different PDE isozymes, particularly PDE3A vs PDE3B, in the regulation of heart function remains unclear.

OBJECTIVE

To determine the relative contribution of PDE3A vs PDE3B isozymes in the regulation of heart function and to dissect the molecular basis for this regulation.

METHODS AND RESULTS

Compared with wild-type littermates, cardiac contractility and relaxation were enhanced in isolated hearts from PDE3A(-/-), but not PDE3B(-/-), mice. Furthermore, PDE3 inhibition had no effect on PDE3A(-/-) hearts but increased contractility in wild-type (as expected) and PDE3B(-/-) hearts to levels indistinguishable from PDE3A(-/-). The enhanced contractility in PDE3A(-/-) hearts was associated with cAMP-dependent elevations in Ca(2+) transient amplitudes and increased sarcoplasmic reticulum (SR) Ca(2+) content, without changes in L-type Ca(2+) currents of cardiomyocytes, as well as with increased SR Ca(2+)-ATPase type 2a activity, SR Ca(2+) uptake rates, and phospholamban phosphorylation in SR fractions. Consistent with these observations, PDE3 activity was reduced ≈8-fold in SR fractions from PDE3A(-/-) hearts. Coimmunoprecipitation experiments further revealed that PDE3A associates with both SR calcium ATPase type 2a and phospholamban in a complex that also contains A-kinase anchoring protein-18, protein kinase type A-RII, and protein phosphatase type 2A.

CONCLUSIONS

Our data support the conclusion that PDE3A is the primary PDE3 isozyme modulating basal contractility and SR Ca(2+) content by regulating cAMP in microdomains containing macromolecular complexes of SR calcium ATPase type 2a-phospholamban-PDE3A.

Inotropic therapy: an important role in the treatment of advanced symptomatic heart failure

Inotropic therapy remains an option in the management of patients with advanced heart failure symptoms from systolic dysfunction who do not respond to conventional therapies. The decision to use this class is largely predicated on an accurate evaluation of the patient's fluid and perfusion status. Selection of the appropriate agent and dosing regimens requires an understanding of the underlying pathophysiology of heart failure and concomitant therapy. Most important, the goals of care should be stated clearly, given inherent risks associated with this class of drug.

Positive inotropes in heart failure: a review article

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

Inotropic therapy for end-stage heart failure patients

OPINION STATEMENT

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

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

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

Effects of cilostazol in the heart

Cilostazol is a selective phosphodiesterase 3 (PDE3) inhibitor approved by the Food and Drug Administration for treatment of intermittent claudication. It has also been used in bradyarrhythmic patients to increase heart rates. Recently, cilostazol has been shown to prevent ventricular fibrillation in patients with Brugada syndrome. Cilostazol is hypothesized to suppress transient outward potassium (Ito) current and increase inward calcium current, thus, maintaining the dome (phase 2) of action potential, decreasing transmural dispersion of repolarization and preventing ventricular fibrillation. Although many PDE3 inhibitors have been shown to increase cardiac arrhythmia in heart failure, cilostazol has presented effects that are different from other PDE3 inhibitors, especially adenosine uptake inhibition. Owing to this effect, cilostazol could be an effective cardioprotective drug, with its beneficial effects in preventing arrhythmia. In this review, the cardiac electrophysiological effects of cilostazol are presented and its possible cardioprotective effects, particularly in preventing ventricular fibrillation, are discussed, with emphasis on the need to further verify its clinical benefits.

Combination therapy with beta-adrenergic receptor antagonists and phosphodiesterase inhibitors for chronic heart failure

Abstract Rational use of phosphodiesterase inhibitors represents an ongoing controversy in contemporary pharmacotherapy for heart failure. In randomized clinical trials, phosphodiesterase inhibitors increased cardiac output at the expense of worsening the rates of sudden cardiac death and cardiovascular mortality. Preliminary findings from ongoing clinical and preclinical investigations of phosphodiesterase activity suggest that combined use of phosphodiesterase inhibitors with beta-adrenergic antagonists may prevent these adverse outcomes. Compartmentation of cyclic adenosine 3',5'-monophosphate signaling may prove critical in determining myocardial response to combination therapy.

Maximizing management of patients with decompensated heart failure

Patients with decompensated congestive heart failure can be categorized into those with either acute or chronic presentations. Patients with acute decompensated heart failure most often have an acute injury that affects either myocardial performance (i.e., myocardial infarction) or valvular/chamber integrity (mitral regurgitation, ventricular septal rupture), which leads to an acute rise in left ventricular (LV) filling pressures resulting in pulmonary edema and dyspnea. Therapy for these patients is aimed at treating the underlying cause of the myocardial injury as well as pharmacologic strategies to reduce LV filling pressures and to improve cardiac performance. In contrast, the therapy of patients presenting with decompensated heart failure in the setting of chronic LV systolic dysfunction, treated with angiotensin-converting enzyme inhibitors, digoxin, diuretics, and may be beta blockers, represent a poorly defined clinical entity that lacks clear guidelines for treatment. These patients can present with symptoms of volume overload and/or low cardiac output without evidence for a volume overloaded state. Potential diagnostic and therapeutic approaches include (1) a pulmonary artery catheter for invasive hemodynamic monitoring, (2) intravenous inotropic therapy, (3) LV mechanical assist device therapy, and (4) cardiac transplantation. This review presents some of the advantages and disadvantages of each of these interventions for patients with chronic systolic dysfunction who present with decompensated symptoms and require specialized management in the hospital setting.

Myocardial protection in sepsis

Sepsis with myocardial dysfunction is seen commonly. Beta-blockers have been used successfully to treat chronic heart failure based on the premise that chronically elevated adrenergic drive is detrimental to the myocardium. However, recent reports on the acute use of beta-blockers in situations with potential hemodynamic compromise have shown the risks associated with this approach. In critical situations, the main effect of adrenergic activation is to support cardiovascular function. Caution should be exercised in designing studies to assess beta-blockers in septic patients.

Pediatric heart failure therapy with beta-adrenoceptor antagonists

Management of chronic heart failure in pediatrics has been altered by the adult literature showing improvements in mortality and hospitalization rates with the use of beta-adrenoceptor antagonists (beta-blockers) for routine therapy of all classes of ischemic and non-ischemic heart failure. Many pediatric heart failure specialists have incorporated these agents into their routine management of pediatric heart failure related to dilated cardiomyopathy or ventricular dysfunction in association with congenital heart disease. Retrospective and small prospective case series have shown encouraging improvements in cardiac function and symptoms, but interpretation has been complicated by the high rate of spontaneous recovery in pediatric patients. A recently completed pediatric double-blind, randomized, placebo-controlled clinical trial showed no difference between placebo and two doses of carvedilol over a 6-month period of follow-up, with significant improvement of all three groups over the course of evaluation. Experience with adults has suggested that only certain beta-blockers, including carvedilol, bisoprolol, nebivolol, and metoprolol succinate, should be used in the treatment of heart failure and that patients with high-grade heart failure may derive the most benefit. Other studies surmise that early or prophylactic use of these medications may alter the risk of disease progression in some high-risk subsets, such as patients receiving anthracyclines or those with muscular dystrophy. This article reviews these topics using experience as well as data from all the recent pediatric studies on the use of beta-blockers to treat congestive heart failure, especially when related to systolic ventricular dysfunction.

Low-dose oral enoximone enhances the ability to wean patients with ultra-advanced heart failure from intravenous inotropic support: results of the oral enoximone in intravenous inotrope-dependent subjects trial

BACKGROUND

We determined whether low-dose oral enoximone could wean patients with ultra-advanced heart failure (UA-HF) from intravenous (i.v.) inotropic support. Chronic parenteral inotropic therapy in UA-HF is costly and requires an indwelling catheter. An effective and safe oral inotrope would have value.

METHODS

In this placebo-controlled study, 201 subjects with UA-HF requiring i.v. inotropic therapy were randomized to enoximone or placebo. Subjects receiving intermittent i.v. inotropes were administered study medication of 25 or 50 mg 3 times a day (tid). Subjects receiving continuous i.v. inotropes were administered 50 or 75 mg tid for 1 week, which was reduced to 25 or 50 mg tid. The ability of subjects to remain alive and free of inotropic therapy was assessed for up to 182 days.

RESULTS

Thirty days after weaning, 51 (51%) subjects on placebo and 62 (61.4%) subjects in the enoximone group were alive and free of i.v. inotropic therapy (unadjusted primary end point P = 0.14, adjusted for etiology P = .17). At 60 days, the wean rate was 30% in the placebo group and 46.5% in the enoximone group (unadjusted P = .016) Kaplan-Meier curves demonstrated a trend toward a decrease in the time to death or reinitiation of i.v. inotropic therapy over the 182-day study period (hazard ratio 0.76 [95% CI 0.55-1.04]) and a reduction at 60 days (0.62 [95% CI 0.43-0.89], P = .009) and 90 days (0.69 [95% CI 0.49-0.97], P = .031) after weaning in the enoximone group.

CONCLUSIONS

Although there was no benefit over placebo in weaning patients from i.v. inotropes from 0 to 30 days, the EMOTE data suggest that low-dose oral enoximone can be used to wean a modest percentage of subjects from i.v. inotropic support for up to 90 days after initiation of therapy.

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.

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.

Tolerability of beta-blockers in outpatients with refractory heart failure who were receiving continuous milrinone

STUDY OBJECTIVE

To investigate the dosing, tolerability, and outcomes associated with the use of concomitant beta-blockers and inotropic therapy in patients with refractory heart failure during the first 6 months of their therapy.

DESIGN

Retrospective review.

SETTING

University-based, tertiary care heart failure and transplant center.

PATIENTS

Sixteen inotrope-dependent outpatients with end-stage refractory heart failure who were receiving continuous intravenous milrinone. Of these patients, 12 also received an oral beta-blocker; the remaining four patients who did not receive beta-blockers served as the comparator group.

MEASUREMENTS AND MAIN RESULTS

For each patient, the initial and final study drug doses of continuous intravenous milrinone and oral beta-blocker treatment, when applicable, were recorded over the 6-month period. Mean heart rate, blood pressure, ejection fraction, and oxygen consumption were measured, and 95% confidence intervals were calculated. Serum sodium and creatinine concentrations, as well as the creatinine clearance, were measured. In the 12 patients who received concomitant milrinone and beta-blockers, the mean baseline ejection fraction was approximately 18%, and they received milrinone for 18.6 weeks. Seven patients received carvedilol for 16.1 weeks, and five received metoprolol tartrate for 17.6 weeks. Dosages of the beta-blockers were titrated. Final daily doses were carvedilol 42.8 mg (95% confidence interval 20.3-65.4) and metoprolol 42.5 mg (95% confidence interval 28.0-57.2). Patients continued to receive other standard oral drug therapy for heart failure. One patient discontinued metoprolol and one discontinued carvedilol because of hypotension and/or worsening heart failure. Cardiac adverse events in the concomitant milrinone plus beta-blocker group were heart failure requiring hospitalization in 10 patients and ventricular arrhythmias in one.

CONCLUSION

Inotrope-dependent patients with refractory end-stage heart failure tolerated continuous intravenous milrinone plus beta-blockers in addition to diuretics and vasodilators for the 6-month observation period. Beta-blocker dosages were titrated, and three patients achieved the target beta-blocker dosage established for stage A-C heart failure. Additional studies are needed to determine the optimal selection and dosing of drug combinations in this population.

Tips and tricks on outpatient initiation and uptitration of beta-blockade in heart failure

beta-blockade has a therapeutic role across the continuum of patients with heart failure (HF), with a demonstrated mortality benefit in stage II and III HF. Concerns regarding initiation and uptitration linger as patients with resting bradycardia, pulmonary, or vascular disease are often unnecessarily excluded from receiving therapy. We will review the risk data on beta-blockade and offer therapeutic strategies to help overcome residual barriers to the initiation and uptitration of this important therapy in patients with HF.

Inhibition of histone deacetylase on ventricular remodeling in infarcted rats

Histone deacetylase (HDAC) determines the acetylation status of histones and, thereby, controls the regulation of gene expression. HDAC inhibitors have been shown to inhibit cardiomyocyte growth in vitro and in vivo. We assessed whether HDAC inhibitors exert a beneficial effect on the remodeling heart in infarcted rats. At 24 h after ligation of the left anterior descending artery, male Wistar rats were randomized to vehicle, HDAC inhibitors [valproic acid (VPA) and tributyrin], an agonist of HDAC (theophylline), VPA + theophylline, or tributyrin + theophylline for 4 wk. Significant ventricular hypertrophy was detected as increased myocyte size at the border zone isolated by enzymatic dissociation after infarction. Cardiomyocyte hypertrophy and collagen formation at the remote region and border zone were significantly attenuated by VPA and tributyrin with a similar potency compared with that induced by the vehicle. Left ventricular shortening fraction was significantly higher in the VPA- and tributyrin-treated groups than in the vehicle-treated group. Increased synthesis of atrial natriuretic peptide mRNA after infarction was confirmed by RT-PCR, consistent with the results of immunohistochemistry and Western blot for acetyl histone H4. The beneficial effects of VPA and tributyrin were abolished by theophylline, implicating HDAC as the relevant target. Inhibition of HDAC by VPA or tributyrin can attenuate ventricular remodeling after infarction. This might provide a worthwhile therapeutic target.

Myocardial phosphodiesterases and regulation of cardiac contractility in health and cardiac disease

Phosphodiesterase (PDE) inhibitors are potent cardiotonic agents used for parenteral inotropic support in heart failure. Contractile effects of these agents are mediated through cAMP-protein kinase A-induced stimulation of I (Ca2+) which ultimately results in increased Ca(2+)-induced sarcoplasmic reticulum Ca(2+) release. A number of additional effects such as increases in sarcoplasmic reticulum Ca(2+) stores, stimulation of reverse mode Na(+)-Ca(2+) exchange, direct or cAMP-mediated effects on sarcoplasmic reticulum ryanodine receptor, stimulation of the voltage-sensitive sarcoplasmic reticulum Ca(2+) release mechanism, as well as A(1) adenosine receptor blockade could contribute to positive inotropic responses to PDE inhibitors. Moreover, some PDE inhibitors exhibit Ca(2+) sensitizer properties as they could increase the affinity of troponin C Ca(2+)-binding sites as well as reduce Ca(2+) threshold for thin myofilament sliding and facilitate cross-bridge cycling. Inotropic responses to PDE inhibitors are significantly reduced in cardiac disease, an effect largely attributed to downregulation of cAMP-mediated signalling due to sustained sympathetic activation. Four PDE isoenzymes (PDE1, PDE2, PDE3 and PDE4) are present in myocardial tissue of various mammalian species, of which PDE3 and PDE4 are particularly involved in regulation of cardiac myocyte contraction. PDE cAMP-hydrolysing activity is preserved in compensated cardiac hypertrophy but significantly reduced in animal models of heart failure. However, clinical studies have not revealed any changes in distribution profile as well as kinetic and regulatory properties of myocardial PDEs in failing human hearts. A reduction of PDE inhibitors-induced contractile responses in heart failure has therefore been ascribed to reduced cAMP synthesis due to uncoupling of adenylyl cyclase from beta-adrenoreceptor. In cardiac myocytes, PDEs are targeted to distinct subcellular compartments by scaffolding proteins such as myomegalin, mAKAP and beta-arrestins. Over subcellular microdomains, cAMP hydrolysis by PDE3 and PDE4 allows to control the activity of local pools of protein kinase A and therefore the extent of protein kinase A-mediated phosphorylation of cellular proteins.

Levosimendan and prostaglandin E1 for uptitration of beta-blockade in patients with refractory, advanced chronic heart failure

BACKGROUND

In advanced chronic heart failure (CHF) 20% of patients do not tolerate beta-blockers and 50% do not reach target doses.

AIM

To test whether levosimendan or prostaglandin E1 (PGE1) can facilitate uptitration of beta-blockers in advanced CHF.

METHODS AND RESULTS

Seventy-five advanced CHF patients (LVEF<35%, NYHA class IIIb or IV) intolerant to beta-blocker uptitration to target doses (10 mg bisoprolol/day) were randomised to a monthly 24 h infusion with levosimendan (n=39) or a chronic infusion with PGE1 (n=36) for 3 months. Bisoprolol was uptitrated following predefined criteria. At 12 weeks, bisoprolol dose increased from 4 mg to 10 mg in both groups. Heart failure worsening occurred in 29 levosimendan patients (74%) versus 16 PGE1 patients (44%, p=0.008). Uptitration was impossible in 9 levosimendan patients (23%) versus 2 PGE1 patients (6%, p=0.03). The combined endpoint of death or urgent heart transplantation or implantation of a ventricular assist device was reached by 12 levosimendan patients (31%) versus 4 PGE1 patients (11%, p=0.04). After 1 year, LVEF increased from 23+/-7% to 28+/-11% (p=0.0004), and BNP decreased from 994+/-806 to 659+/-564 pg/ml (p=0.03).

CONCLUSION

Levosimendan and PGE1 facilitate uptitration of beta-blockers in previously intolerant CHF patients. PGE1 treatment allowed uptitration in more patients and resulted in a better clinical outcome compared to levosimendan. This approach increased LVEF and decreased BNP after 1 year.

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.

Ca2+-sensitisers--a promising option to treat heart failure?

Because the number of transplants is still fewer than the number of patients waiting for a donor organ, new concepts of therapy are needed that allow patients to bridge the time gap until heart transplantation or even to improve symptoms while on treatment. Ca(2+)-sensitisers are agents that directly influence myofilaments and/or the cross-bridge-cycle. Depending on the molecular mechanisms underlying their action, Ca(2+)-sensitisers have been divided into three classes. While, a number of Ca(2+)-sensitising drugs have been described, currently only the Ca(2+)-sensitisers pimobendan and levosimendan are in clinical use. This review provides a survey on the molecular mechanisms and the therapeutic effectiveness of Ca(2+)-sensitisers for the treatment of human heart failure.

Reevaluating the role of phosphodiesterase inhibitors in the treatment of cardiovascular disease

First developed for clinical use in the late 1980s, the phosphodiesterase inhibitors were found to increase the levels of the ubiquitous second messenger cyclic adenosine monophosphate and could effect changes in vascular tone, cardiac function, and other cellular events. After several early studies using high doses of phosphodiesterase inhibitors in patients with severe heart failure suggested adverse consequences, they fell out of favor. However, recent investigations of phosphodiesterase inhibitors in patients with intermittent claudication have demonstrated profound benefits. Furthermore, these agents have proven useful in prevention of cerebral infarction and coronary restenosis, and their use in the treatment of heart failure is being reevaluated. The reemergence of phosphodiesterase inhibitors can be attributed to a better understanding of dosing and drug-specific pharmacology, the use of concomitant medications, and a recognition of unique ancillary properties; however, their use still requires caution.

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.

Acute heart failure: inotropic agents and their clinical uses

Inotropic agents are indispensable for the improvement of cardiac contractile dysfunction in acute or decompensated heart failure. Clinically available agents, including sympathomimetic amines (dopamine, dobutamine, noradrenaline) and selective phosphodiesterase-3 inhibitors (amrinone, milrinone, olprinone and enoximone) act via cAMP/protein kinase A (PKA)-mediated facilitation of intracellular Ca2+ mobilisation. Phosphodiesterase-3 inhibitors also have a vasodilatory action, which plays a role in improving haemodynamic parameters in certain patients, and are termed inodilators. The available inotropic agents suffer from risks of Ca2+ overload leading to arrhythmias, myocardial cell injury and ultimately, cell death. In addition, they are energetically disadvantageous because of an increase in activation energy and cellular metabolism. Furthermore, they lose their effectiveness under pathophysiological conditions, such as acidosis, stunned myocardium and heart failure. Pimobendan and levosimendan (that act by a combination of an increase in Ca2+ sensitivity and phosphodiesterase-3 inhibition) appear to be more beneficial among existing agents. Novel Ca2+ sensitisers that are under basic research warrant clinical trials to replace available inotropic agents.

Cardiovascular effects of a phosphodiesterase III inhibitor in the presence of carvedilol in dogs

The aim of this study was to determine whether dobutamine, dopamine, or milrinone (a phosphodiesterase [PDE] III inhibitor) would support cardiac function that had been attenuated by administration of the beta-blocker, carvedilol (0.2, 0.4, or 0.8 mg/kg). Hemodynamic and cardiac parameters including the heart rate (HR), left-ventricular fractional shortening (FS), and arterial pressure were measured in six healthy dogs without cardiac disease. Carvedilol did not affect FS or arterial pressure, but decreased the HR significantly. The positive inotropic and chronotropic responses to dobutamine and dopamine were attenuated by carvedilol, whereas arterial pressure was unaffected. Milrinone did not affect the HR and decreased arterial pressure, whereas FS was significantly greater both in the control and carvedilol-treated groups. Although milrinone affect the negative chronotropic effects of carvedilol, milrinone increased FS and prevented the decrease in arterial pressure. These results suggest that inhibition of PDE III preserves cardiac contractility and hemodynamic function in the presence of carvedilol.

Inhibitors of cyclic nucleotide phosphodiesterase 3 and 5 as therapeutic agents in heart failure

Cyclic nucleotide phosphodiesterases (PDE) 3 and 5 regulate cAMP and cGMP signalling in cardiac and smooth muscle myocytes. Important advances in the understanding of the roles of these enzymes have recently been made. PDE3 inhibitors have inotropic and vasodilatory properties, and although they acutely improve haemodynamics in patients with heart failure, they do not improve long-term morbidity and mortality. Although combination therapy with beta-adrenergic receptor antagonists or selective inhibition of specific PDE3 isoforms might result in a more favourable long-term outcome, more clinical data are needed to test this proposition. The role of PDE5 inhibitors in the treatment of cardiac disease is evolving. PDE5 inhibitors cause pulmonary and systemic vasodilation. How these drugs will compare with other vasodilators in terms of long-term outcomes in patients with heart failure is unknown. Recent studies also suggest that PDE5 inhibitors may have antihypertropic effects, exerted through increased myocardial cGMP signalling, that could be of additional benefit in patients with heart failure.

The long-term survival benefit conferred by intermittent dobutamine infusions and oral amiodarone is greater in patients with idiopathic dilated cardiomyopathy than with ischemic heart disease

BACKGROUND

Intermittent dobutamine infusions (IDI) combined with oral amiodarone improve the survival of patients with end-stage congestive heart failure (CHF). The purpose of the present study was to evaluate whether the response to long-term treatment with IDI+amiodarone is different in patients with ischemic heart disease (IHD) versus idiopathic dilated cardiomyopathy (IDC).

METHODS

The prospective study population consisted of 21 patients with IHD (the IHD Group) and 16 patients with IDC (the IDC Group) who presented with decompensated CHF despite optimal medical therapy, and were successfully weaned from an initial 72-h infusion of dobutamine. They were placed on a regimen of oral amiodarone, 400 mg/day and weekly IDI, 10 microg/kg/min, for 8 h.

RESULTS

There were no differences in baseline clinical and hemodynamic characteristics between the 2 groups. The probability of 2-year survival was 44% in the IDC Group versus 5% in the IHD Group (long-rank, P=0.004). Patients with IDC had a 77% relative risk reduction in death from all causes compared to patients with IHD (odd ratio 0.27, 95% confidence interval 0.13 to 0.70, P=0.007). In contrast, no underlying disease-related difference in outcomes was observed in a retrospectively analyzed historical Comparison Group of 29 patients with end stage CHF treated by standard methods.

CONCLUSIONS

Patients with end stage CHF due to IDC derived a greater survival benefit from IDI and oral amiodarone than patients with IHD.