Parenteral inotropic support for advanced congestive heart failure

A single German center experience with intermittent inotropes for patients on the high-urgent heart transplant waiting list

AIM

Currently, more than 900 patients with end-stage heart failure are listed for heart transplantation in Germany. All patients on the Eurotransplant high-urgent status (HU) have to be treated in intensive care units and have to be relisted every 8 weeks. Long-term continuous inotropes are associated with tachyphylaxia, arrhythmias and even increased mortality. In this retrospective analysis, we report our single center experience with HU patients treated with intermittent inotropes as a bridging therapy.

METHODS AND RESULTS

117 consecutive adult HU candidates were treated at our intensive care heart failure unit between 2008 and 2013, of whom 14 patients (12 %) were stabilized and delisted during follow-up. In the remaining 103 patients (age 42 ± 15 years), different inotropes (dobutamine, milrinone, adrenaline, noradrenaline, levosimendan) were administered based on the patient's specific characteristics. After initial recompensation, patients were weaned from inotropes as soon as possible. Thereafter, intermittent inotropes (over 3-4 days) were given as a predefined weekly (until 2011) or 8 weekly regimen (from 2011 to 2013). In 57 % of these patients, additional regimen-independent inotropic support was necessary due to hemodynamic instabilities. Fourteen patients (14 %) needed a left- or biventricular assist device; 14 patients (14 %) died while waiting and 87 (84 %) received heart transplants after 87 ± 91 days. Cumulative 3 and 12 months survival of all 103 patients was 75 and 67 %, respectively.

CONCLUSION

Intermittent inotropes in HU patients are an adequate strategy as a bridge to transplant; the necessity for assist devices was low. These data provide the basis for a prospective multicenter trial of intermittent inotropes in patients on the HU waiting list.

Comparison of single-dose and repeated levosimendan infusion in patients with acute exacerbation of advanced heart failure

BACKGROUND

Levosimendan (LS) is a novel inodilator that improves cardiac performance, central hemodynamics, and symptoms of patients with decompensated chronic heart failure. The aim of this study was to compare the effects of single and repeated LS infusion on left ventricular performance, biomarkers, and neurohormonal activation in patients with acute heart failure.

MATERIAL AND METHODS

Twenty-nine consecutive patients with acute exacerbation of advanced heart failure were included in this study. LS was initiated as a bolus of 6 μg/kg followed by a continuous infusion of 0.1 μg/kg/min for 24 hours in both groups who received intravenous single and repeated (baseline and at 1 and 3 months) treatment. Physical examination, echocardiography, and biochemical tests (brain natriuretic peptide, tumour necrosis factor-alpha, interleukin-1beta, 2, and 6) were performed before treatment and on 3 day of the treatment. The last evaluation was performed at 6 month after the baseline treatment.

RESULTS

Twenty male and 9 female patients with mean age of 60.2 ± 7.4 years were included in this study. A significant improvement in New York Heart Association functional status and myocardial performance index was detected only in the repeated LS treated patients at 6 month compared to the pretreatment status (p=0.03 and p<0.001; respectively). In addition, a significant decrease in brain natriuretic peptide (p<0.01) and plasma interleukin-6 (p=0.05) levels were also achieved only in patients who were given repeated LS.

CONCLUSIONS

Our study showed that repeated LS treatment is more effective compared to the single dose LS treatment in improving clinical status, hemodynamic and laboratory parameters in patients with acute exacerbation of advanced heart failure.

Milrinone in Advanced Heart Failure

Advanced chronic heart failure (ACHF) patients often require inotropes before transplantation or ventricular assist device implantation. Milrinone, an inotrope and vasodilator, may accumulate in cardiorenal syndrome with serious adverse effects. We investigated the potential for therapeutic drug monitoring of milrinone levels using High Performance Liquid Chromatography Mass Spectrometry (HPLC-MS). 22 ACHF patients (15 males, 49±9 years) received milrinone 50 µg/kg intravenously (i.v.) during heart catheterization. Milrinone levels were 216±71 ng/ml (within the reported therapeutic range: 100-300 ng/ml), followed by improvements in cardiac index, pulmonary artery and wedge pressures (p < 0.005). 18 ACHF patients (17 males, 50±12 years, 13 had renal dysfunction) received continuous i.v. milrinone (5-26 days) at 0.1-0.2 µg/kg/min, titrated according to plasma milrinone levels. No adverse events occurred. Therapeutic levels were achieved with doses of 0.2±0.06 µg/Kg/min, below those recommended in Summary of Product Characteristics. Milrinone therapy can be noninvasively monitored by HPLC-MS, while avoiding toxicity in ACHF.

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

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

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

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

Inoprotection: the perioperative role of levosimendan

Levosimendan is emerging as a novel cardioprotective inotrope. Levosimendan augments myocardial contractility by sensitising contractile myofilaments to calcium without increasing myosin adenosine triphosphatase activity or oxygen consumption. Levosimendan activates cellular adenosine triphosphate-dependent potassium channels, a mechanism which is postulated to protect cells from ischaemia in a manner similar to ischaemic preconditioning. Levosimendan may therefore protect the ischaemic myocardium during ischaemia-reperfusion as well as improve the contractile function of the heart. Adenosine triphosphate-dependent potassium channel activation by levosimendan may also be protective in other tissues, such as coronary vascular endothelium, kidney and brain. Clinical trials in patients with decompensated heart failure and myocardial ischaemia show levosimendan to improve haemodynamic performance and potentially improve survival. This paper reviews the known pharmacology of levosimendan, the clinical experience with the drug to date and the potential use of levosimendan as a cardioprotective agent during surgery.

Cardiovascular pharmacotherapy update for the intensive care unit

Pharmacologic agents including vasodilators, inotropes, and vasopressors are frequently used in the critical care setting for management of the unstable cardiac patient. These medications are used to elicit varying effects on vascular resistance, myocardial contractility, and heart rate to help achieve desired hemodynamic and clinical endpoints. Therefore, it is important for the critical care nurse to have a practical understanding and working knowledge of cardiovascular pharmacotherapy in the intensive care unit setting. This article reviews the pharmacology and clinical utility of commonly used intravenous "vasoactive" medications encountered in the intensive care unit. We also highlight innovations in pharmacotherapy for this patient population, and provide practical considerations for the most appropriate and safe use of these medications.

The utility of levosimendan in the treatment of heart failure

Calcium sensitizers are a new group of inotropic drugs. Levosimendan is the only calcium sensitizer in clinical use in Europe. Its mechanism of action includes both calcium sensitization of contractile proteins and the opening of adenosine triphosphate (ATP)-dependent potassium channels as mechanism of vasodilation. The combination of K-channel opening with positive inotropy offers potential benefits in comparison to currently available intravenous inotropes, since K-channel opening protects myocardium during ischemia. Due to the calcium-dependent binding of levosimendan to troponin C, the drug increases contractility without negative lusitropic effects. In patients with heart failure levosimendan dose-dependently increases cardiac output and reduces pulmonary capillary wedge pressure. Since levosimendan has an active metabolite OR-1896 with a half-life of some 80 hours, the duration of the hemodynamic effects significantly exceeds the 1-hour half-life of the parent compound. The hemodynamic effects of the levosimendan support its use in acute and postoperative heart failure. Several moderate-size trials (LIDO, RUSSLAN, CASINO) have previously suggested that the drug might even improve the prognosis of patients with decompensated heart failure. These trials were carried out in patients with high filling pressures. Recently two larger trials (SURVIVE and REVIVE) in patients who were hospitalized because of worsening heart failure have been finalized. These trials did not require filling pressures to be measured. The two trials showed that levosimendan improves the symptoms of heart failure, but does not improve survival. The results raise the question whether a 24-hour levosimendan infusion can be used without invasive hemodynamic monitoring.

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.

Medical and Ventilatory Treatment of Acute Heart Failure: New Insights

BACKGROUND

The traditional medical treatment of acute heart failure (AHF) has remained unchanged for many years. It has been based on oxygen supplementation and mechanical ventilatory support as well as the administration of morphine, diuretics, nitrates and inotropic agents. In 2005 the European Society of Cardiology (ESC) published new guidelines on the diagnosis and treatment of AHF. Also, new therapies have been introduced recently, giving rise to changes in therapeutic concepts.

MATERIAL/METHOD

Based on these new guidelines and recent studies selected from the literature we here describe the new ESC classification of AHF including its epidemiology and pathophysiology. We further present a state-of-the-art status of the choices of medical treatment for patients with acute decompensated heart failure and pulmonary edema.

RESULTS

Mechanical ventilatory support reduces the number of patients who require endotracheal intubation. Nitrates in dosages higher than employed today appear to be beneficiary to patients with pulmonary congestion, probably because of the pronounced afterload-reducing effect. Nesiritide, a synthetic brain natriuretic peptide, has shown better hemodynamic effects than common nitrate dosages in patients with congestive heart failure. Tezosentan, an endothelin antagonist, was tested in the biggest AHF trial ever, which, however, was terminated prematurely because it was futile to proceed given the endpoints dyspnea and death. The beta1-adrenergic drug dobutamine and the phosphodiestherase inhibitor milrinone are associated with increased mortality in patients with pronounced chronic and acute congestive heart failure. Levosimendan, a new inotropic drug, has shown lower mortality compared to dobutamine in patients with acute congestive heart failure.

CONCLUSION

New concepts have finally emerged, including the application of old drugs such as nitrates in new (i.e., higher) dosages, as well as the novel compound levosimendan, recommended for patients with AHF and hypoperfused organs. The new ESC classification of AHF provides a valuable and long-awaited guideline to diagnose and treat this severe condition.

Pharmacological Mechanisms Contributing to the Clinical Efficacy of Levosimendan

Acute decompensation of chronic heart failure is a direct life-threatening situation with short-term mortality approaching 30%. A number of maladaptive changes are amplified within the cardiovascular system during the progression of chronic heart failure that makes the decompensation phase difficult to handle. Levosimendan is a new Ca2+-sensitizer for the treatment of acutely decompensated heart failure that has proved to be effective during the decompensation of chronic heart failure and acute myocardial infarction. Levosimendan differs from other cardiotonic agents that are used for acute heart failure in that it utilizes a unique dual mechanism of action: Ca2+-sensitization through binding to troponin C in the myocardium, and the opening of ATP-sensitive K+ channels in vascular smooth muscle. In general, these mechanisms evoke positive inotropy and vasodilation. Clinical studies suggested long-term benefits on mortality following short-term administration. It may, therefore, be inferred that levosimendan has additional effects on the cardiovascular system that are responsible for the prolongation of survival. Results of preclinical and clinical investigations suggest that the combination of levosimendan-induced cardiac and vascular changes has favorable effects on the coronary, pulmonary and peripheral circulations. Redistribution of the circulating blood offers an improved hemodynamic context for the development of a positive inotropic effect through Ca2+-sensitization of the contractile filaments, without a proportionate increase in myocardial oxygen consumption or the development of arrhythmias. Activation of ATP-sensitive K+ channels, both on sarcolemma and mitochondria, may protect against myocardial ischemia, and decreased levels of cytokines may prevent the development of further myocardial remodeling. Collectively, these effects of levosimendan shift the disturbed cardiovascular parameters towards normalization, thereby halting the perpetuation of the vicious cycle of heart failure progression. This may contribute to stabilization of the circulation and improved life expectancy of patients with chronic heart failure.

Levosimendan improves postresuscitation outcomes in a rat model of CPR

In this study we sought to determine whether a calcium sensitizer, levosimendan, would have a more favorable effect on postresuscitation myocardial function and, consequently, postresuscitation survival than beta-adrenergic dobutamine. The extreme decrease in survival before hospital discharge of resuscitated victims is attributed, in part, to postresuscitation myocardial failure, and dobutamine has been recommended for the management of postresuscitation myocardial failure. We studied a total of 15 animals. Ventricular fibrillation was induced in Sprague-Dawley rats weighing 450 to 550 g. Cardiopulmonary resuscitation (CPR), including chest compressions and mechanical ventilation, was begun after 8 minutes of untreated cardiac arrest. Electrical defibrillation was attempted after 6 minutes of CPR. Each animal was resuscitated. Animals were randomized to undergo treatment with levosimendan, dobutamine, or saline-solution placebo. These agents were administered 10 minutes after the return of spontaneous circulation. Levosimendan was administered in a loading dose of 12 microg kg(-1) over a 10-minute period, followed by infusion of 0.3 microg kg(-1) min(-1) over the next 230 minutes. Dobutamine was continuously infused at a dosage of 3 microg kg(-1) min(-1). Saline-solution placebo was administered in the same volume and over the same amount of time as levosimendan. Levosimendan and dobutamine produced comparable increases in cardiac output and rate of left-ventricular pressure increase. However, administration of levosimendan resulted in lower heart rates and lesser increases in left ventricular diastolic pressure compared with both dobutamine and placebo. The duration of postresuscitation survival was significantly greater with levosimendan (16 +/- 2 hours), intermediate with dobutamine (11 +/- 2 hours) and least with saline-solution placebo (8 +/- 1 hour). Levosimendan and dobutamine both improved postresuscitation myocardial function. However, levosimendan produced more favorable postresuscitation myocardial function and increased the duration of postresuscitation survival.

Levosimendan: a calcium-sensitizing agent for the treatment of patients with decompensated heart failure

Levosimendan is a new inodilator. Its mechanism of action includes calcium sensitization of contractile proteins and the opening of adenosine triphosphate-dependent K channels. The combination of positive inotropy with anti-ischemic effects of K-channel opening offers potential benefits in comparison with currently available intravenous inotropes, which are contraindicated in patients with ongoing myocardial ischemia. Levosimendan has been extensively studied in various animal models of heart failure, in which the drug has increased contractility without adverse effects on diastolic function. These results have been repeated in patients with heart failure, in whom levosimendan dose-dependently increases cardiac output and reduces pulmonary capillary wedge pressure. The active metabolite of levosimendan (OR-1896) significantly prolongs the duration of the hemodynamic effects of the therapeutic 24-hour levosimendan infusion. Levosimendan has been studied in two major trials with decompensated patients (LIDO and RUSSLAN), in which it showed outcome benefits in comparison with dobutamine and placebo, respectively. A third comparative study (CASINO) recently suggested mortality benefits with levosimendan over placebo and dobutamine. Currently, two large prospective trials (SURVIVE and REVIVE) in patients who are hospitalized because of worsening heart failure are underway. These trials will conclusively prove whether levosimendan should be added to the standard treatment in patients who are hospitalized because of cardiac decompensation.

In-hospital mortality in patients with acute decompensated heart failure requiring intravenous vasoactive medications: an analysis from the Acute Decompensated Heart Failure National Registry (ADHERE)

OBJECTIVES

We sought to compare the in-hospital mortality of patients with acute decompensated heart failure (ADHF) who were receiving parenteral treatment with one of four intravenous vasoactive medications.

BACKGROUND

There are limited data regarding the effects of the choice of intravenous vasoactive medication on in-hospital mortality in patients hospitalized with ADHF.

METHODS

This was a retrospective analysis of observational patient data from the Acute Decompensated Heart Failure National Registry (ADHERE), a multicenter registry designed to prospectively collect data on each episode of hospitalization for ADHF and its clinical outcomes. Data from the first 65,180 patient episodes (October 2001 to July 2003) were included in this analysis. Cases in which patients received nitroglycerin, nesiritide, milrinone, or dobutamine were identified and reviewed (n = 15,230). Risk factor and propensity score-adjusted odds ratios (ORs) for in-hospital mortality were calculated.

RESULTS

Patients who received intravenous nitroglycerin or nesiritide had lower in-hospital mortality than those treated with dobutamine or milrinone. The risk factor and propensity score-adjusted ORs for nitroglycerin were 0.69 (95% confidence interval [CI] 0.53 to 0.89, p < or = 0.005) and 0.46 (94% CI 0.37 to 0.57, p < or = 0.005) compared with milrinone and dobutamine, respectively. The corresponding values for nesiritide compared with milrinone and dobutamine were 0.59 (95% CI 0.48 to 0.73, p < or = 0.005) and 0.47 (95% CI 0.39 to 0.56, p < or = 0.005), respectively. The adjusted OR for nesiritide compared with nitroglycerin was 0.94 (95% CI 0.77 to 1.16, p = 0.58).

CONCLUSIONS

Therapy with either a natriuretic peptide or vasodilator was associated with significantly lower in-hospital mortality than positive inotropic therapy in patients hospitalized with ADHF. The risk of in-hospital mortality was similar for nesiritide and nitroglycerin.

Need for hospice and palliative care services in patients with end-stage heart failure treated with intermittent infusion of inotropes

BACKGROUND

Hospice and palliative care programs to relieve suffering and optimize management of terminally ill patients have grown rapidly in the United States. However, there are no data on the need for these services among patients with end-stage heart failure receiving intermittent infusion of intravenous inotropes.

HYPOTHESIS

The need for hospice and palliative care programs among patients in end-stage heart failure who receive intermittent infusion of inotropes is investigated.

METHODS

The study included all stable patients with refractory heart failure symptoms treated with inotropes in our outpatient unit. A total of 73 patients (65 +/- 12 years; left ventricular ejection fraction 22 +/- 9%; New York Heart Association class 3.6 +/- 0.4) were seen during a 49-month period. Of these, 35 patients (48%) met hospice or palliative care evaluation criteria upon referral but were offered, and accepted, the alternative of parenteral inotropes. In all, 1,737 individual outpatient treatment sessions were given, with a mean of 24 +/- 19 sessions per patient (range 5 to 118 sessions), representing a minimum of 9,948 h of inotrope therapy.

RESULTS

A total of 18 (25%) patients died, 6 (8%) patients were withdrawn from the program (3 by their primary physicians and 3 because of significant travel limitations); 4 (5%) patients required continuous intravenous home therapy; and 44 (61%) patients were discharged with significant improvement in their heart failure symptoms. Only 7 of the 18 patients who died had received hospice or palliative care intervention, mainly for the sake of comfort and to ease the transition among family members. The rest of the patients were comfortable and had accepted the natural evolution of their disease; they were not interested in or did not require hospice or palliative care intervention. Of the patients discharged from the outpatient cardiac infusion unit, the interval free of heart failure symptoms after the final infusion treatment ranged from 201 to 489 days, with no need for hospitalization or emergency room visits.

CONCLUSION

Our results demonstrate that intermittent infusion of intravenous inotropes can be safely administered and can improve symptoms in a significant number of patients, probably by slowing the natural progression of heart failure. Although the full clinical impact of inotrope therapy in an outpatient setting has not been fully defined, other nonhemodynamic-related benefits should be sought and investigated. Our results suggest that intermittent infusion of intravenous inotropes is one of the prominent variables that requires particular attention. In our experience, the institution of intermittent infusions of intravenous inotropes can, in fact, modify end-stage heart failure symptoms that, in most patients, are currently perceived to lead to a terminal event. Thus, appropriate use of intermittent infusion of intravenous inotropes may not only improve functional class and symptoms in a significant number of patients identified as terminal by their poor response to conventional therapy, but it may also facilitate better utilization of hospice and palliative care resources among patients with end-stage heart failure. Furthermore, the need for hospice and palliative care in patients with heart failure should be revisited in view of adjuvant treatment options such as intermittent infusion of intravenous inotropes.

Advanced Heart Failure: A Practical Management Algorithm and Therapeutic Options

Despite medical and surgical advances in the management of heart failure, 3%-10% of patients clinically reside in the severe stages of this condition. The management of advanced, end-stage heart failure is one of the major challenges of medicine today. An algorithm applicable to the management of severe heart failure is presented and discussed, with an emphasis on medical treatment and therapeutic options.

Drug treatment of patients with decompensated heart failure

Decompensated heart failure (HF) may be defined as sustained deterioration of at least one New York Heart Association functional class, usually with evidence of sodium retention. Episodes of decompensation are most commonly precipitated by sodium retention, often associated with medication noncompliance. Our therapeutic approach to hospitalized patients is based on the documented hemodynamic responses to vasodilator therapy, with redistribution of mitral regurgitant flow to forward cardiac output and decompression of the left atrium. Invasive hemodynamic monitoring is seldom required for the effective management of patients with HF and there are risks associated with pulmonary artery catheterization. The currently available parenteral vasoactive drugs for decompensated heart failure include: (i) vasodilators such as nesiritide, nitroprusside and nitroglycerin (glyceryl trinitrate); (ii) catecholamine inotropes, primarily dobutamine; and (iii) inodilators such as milrinone, a phosphodiesterase inhibitor. Vasodilators are most appropriate for those patients who are primarily volume-overloaded, but with adequate peripheral perfusion. In this class of agents, nesiritide (recombinant human B-type natriuretic peptide) offers advantages over currently available drugs. Nesiritide produces rapid and sustained decreases in right atrial and pulmonary capillary wedge pressures, with reduction in pulmonary and systemic vascular resistance and increases in cardiac index. The hemodynamic effects of nesiritide infusion were sustained over a duration of 1 week and the drug may be used without intensive monitoring in patients with decompensated HF. Treatment with dobutamine is indicated in patients in whom low cardiac output rather than elevated pulmonary pressure is the primary hemodynamic aberration. However, milrinone reduces left atrial congestion more effectively than dobutamine, and is well tolerated and effective when used in patients receiving beta-blockers. In-patient therapy for decompensated HF is a short term exercise for symptom relief and provides an opportunity to re-assess management in the continuum of care.

Long-term Intermittent Dobutamine Infusion, Combined With Oral Amiodarone for End-Stage Heart Failure

STUDY OBJECTIVES

To examine the effects of long-term intermittent dobutamine infusion, combined with oral amiodarone in patients with congestive heart failure (CHF) refractory to standard medical treatment.

DESIGN

Prospective, randomized, double-blind, placebo-controlled clinical trial.

SETTING

Inpatient and outpatient heart failure clinic in a university teaching hospital.

PATIENTS AND INTERVENTIONS

Thirty patients with end-stage CHF refractory to standard medical treatment who could be weaned from dobutamine therapy after a first 72-h infusion were randomized in a double-blind manner to receive IV infusions of placebo (group 1; 14 patients) vs dobutamine in a dose of 10 micro g/kg/min (group 2; 16 patients) for 8 h every 14 days. All patients received standard medical therapy and also were treated with oral amiodarone, 400 mg/d, which was started at least 2 weeks before randomization.

MEASUREMENTS AND RESULTS

Kaplan-Meier survival analysis showed a 60% reduction in the risk of death from any cause in the group treated with the combination of dobutamine and amiodarone, compared with the group treated with placebo and amiodarone (hazard ratio, 0.403; 95% confidence interval, 0.164 to 0.992; p = 0.048). The 1-year and 2-year survival rates were 69% and 44%, respectively, in the dobutamine-treated group, vs 28% and 21%, respectively, in the placebo-treated group (p < 0.05 for both comparisons). Median survival times were 574 and 144 days, respectively, for groups 2 and 1. At 6 months, the New York Heart Association functional class was significantly improved in the patients who survived from both groups.

CONCLUSIONS

Long-term intermittent dobutamine infusion combined with amiodarone added to the conventional drugs improved the survival of patients with advanced CHF that was refractory to conventional treatment.

Terbutaline for chronotropic support in heart transplantation

OBJECTIVE

To report the use of oral terbutaline for chronotropic support in a patient who had undergone heart transplantation.

CASE SUMMARY

A 54-year-old white man received a heart transplant secondary to ischemic dilated cardiomyopathy. His clinical course was uncomplicated until postoperative day 10, when he became hemodynamically compromised despite inotropic therapy (BP 88/53 mm Hg, mean HR 80 beats/min) secondary to stage IIIa rejection. Although a continuous intravenous infusion of dobutamine was maintained, therapy with oral terbutaline 2.5 mg every 6 hours was initiated. Because the patient remained bradycardic on postoperative day 11 (HR 64 beats/min; mean 75), terbutaline was titrated to a dosage of 5 mg every 8 hours. Subsequently, an improvement in the hemodynamic profile (BP 140/78 mm Hg, mean HR 91 beats/min) was noted. Treatment with terbutaline was continued for 13 days and was well tolerated.

DISCUSSION

As of February 11, 2004, this is the first case, to our knowledge, to describe the use of oral terbutaline therapy for chronotropic support in the setting of acute rejection after heart transplantation. Terbutaline is a beta2-adrenergic agonist that may mediate its effects via direct beta2-receptor stimulation, baroreceptor-mediated increases in sympathetic tone, or via presynaptic beta2-stimulation. Although isoproterenol has been the mainstay of therapy for chronotropic support in this setting, its availability has been an issue in recent years. Terbutaline, therefore, may represent a useful alternative for chronotropic support in the setting of heart transplantation.

CONCLUSIONS

Terbutaline therapy did not appear to be associated with any significant adverse effects and warrants further application and study in this setting.

Pharmacokinetics and Pharmacodynamics of Intravenous Inotropic Agents

Positive inotropic drugs have various mechanisms of action. Long-term use of cyclic adenosine monophosphate (cAMP)-dependent drugs has adverse effects on the prognosis of heart failure patients, whereas digoxin has neutral effect on mortality. There are, however, little data on the effects of intravenous inotropic drugs on the outcome of patients. Intravenous inotropic agents are used to treat cardiac emergencies and refractory heart failure. beta-Adrenergic agonists are rapid acting and easy to titrate, with short elimination half-life. However, they increase myocardial oxygen consumption and are thus hazardous during myocardial ischaemia. Furthermore they may promote myocyte apoptosis. Phosphodiesterase (PDE) III inhibiting drugs (amrinone, milrinone and enoximone) increase contractility by reducing the degradation of cAMP. In addition, they reduce both preload and afterload via vasodilation. Short-term use of intravenous milrinone is not associated with increased mortality, and some symptomatic benefit may be obtained when it is used in refractory heart failure. Furthermore, PDE III inhibitors facilitate weaning from the cardiopulmonary bypass machine after cardiac surgery. Levosimendan belongs to a new group of positive inotropic drugs, the calcium sensitisers. It has complex pharmacokinetics and long-lasting haemodynamic effects as a result of its active metabolites. In comparative trials, it has been better tolerated than the most widely used beta-agonist inotropic drug, dobutamine. The pharmacokinetics of the intravenous inotropic drugs might sometimes greatly modify and prolong the response to the therapy, for example because of long-acting active metabolites. These drugs display considerable differences in their pharmacokinetics and pharmacodynamics, and the selection of the most appropriate inotropic drug for each patient should be based on careful consideration of the clinical status of the patient and on the pharmacology of the drug.

Tratamiento inotrópico en la insuficiencia cardíaca: aspectos generales y resultados clínicos

Classic inotropic agents such as beta-adrenergic agonists and phosphodiesterase III inhibitors have beneficial but transitory hemodynamic effects in patients with acute and chronic heart failure. In this context, the available data suggest that long term inotropic therapy has a negative impact on morbidity and mortality in patients with heart failure. For this reason, these agents are mainly used for the treatment of refractory episodes of decompensation and they are also used as a "bridge" (transplant, revascularization, recovery) or as a palliative measure. We present a revision of the general aspects of inotropes including main published clinical trials and some findings of its combined use with beta blockers. Furthermore, we describe a promising and differential therapeutic approach represented by calcium sensitizer agents (levosimendan).

New and emerging drug therapies for the management of acute heart failure

In recent times, there have been many developments in therapies for acute heart failure, in contrast to the preceding 20 years. These have been mainly fueled by new and expanding knowledge about the pathophysiology of heart failure, which has allowed for insight into potential therapeutic strategies. This review will examine the key emerging therapies for acute heart failure, in light of available pathophysiological and clinical evidence.

New therapies for the management of acute heart failure

The standard treatment for acute heart failure (synonymous with pulmonary edema) is an upright posture, oxygen, morphine (often accompanied by an antiemetic), and intravenous diuretics. This treatment has remained unchanged for many years, and the precise mechanism by which each of these methods alleviates symptoms in patients is unclear. Nitrates, oral or intravenous, are also used with benefit, and have some hemodynamic advantages over intravenous diuretics. Recently, three new forms of treatment have been investigated. The use of milrinone, a phosphodiesterase inhibitor, for exacerbation of heart failure in patients with a background of chronic heart failure was not advantageous. The trials of levosimendan, a calcium sensitizer, in patients with pulmonary edema hinted at benefit. Nesiritide, a formulation of brain natriuretic peptide, does bring about hemodynamic improvement in acute heart failure, and is at least as effective as nitroglycerin, easier to prescribe, but prone to cause hypotension. These are small but important advances that increase our knowledge of the pathophysiology of acute heart failure, and also provide an indication of which drugs are preferable for the treatment of this distressing condition.

The therapeutic potential of novel cardiotonic agents

During the course of treatment of heart failure patients, cardiotonic agents are inevitable for improvement of myocardial dysfunction. Clinically available agents, such as beta-adrenoceptor agonists and selective phosphodiesterase 3 inhibitors, act mainly via cyclic AMP/protein kinase A-mediated facilitation of Ca(2+) mobilisation (upstream mechanism). These agents are associated with the risk of Ca(2+) overload leading to arrhythmias, myocardial cell injury and premature cell death. In addition, they are energetically disadvantageous because of an increase in activation energy and metabolic effects. Cardiac glycosides act also via an upstream mechanism and readily elicit Ca(2+) overload with a narrow safety margin. No currently available agents act primarily via an increase in the myofilament sensitivity to Ca(2+) ions (central and/or downstream mechanisms). Novel Ca(2+) sensitisers under basic research may deserve clinical trials to examine the therapeutic potential to replace currently employed agents in acute and chronic heart failure patients. Molecular mechanisms of action of Ca(2+) sensitisers are divergent. In addition, they show a wide range of discrete pharmacological profiles due to additional actions associated with individual compounds. Therefore, the outcome of clinical trials has to be explained carefully based on these mechanisms of actions.

Beta-blocker therapy influences the hemodynamic response to inotropic agents in patients with heart failure: a randomized comparison of dobutamine and enoximone before and after chronic treatment with metoprolol or carvedilol

OBJECTIVE

We compared the hemodynamic effects of dobutamine and enoximone administration before and after long-term beta-blocker therapy with metoprolol or carvedilol in patients with chronic heart failure (HF).

BACKGROUND

Patients with HF on beta-blocker therapy may need hemodynamic support with inotropic agents, and the hemodynamic response may be influenced by both the inotropic agent and the beta-blocker used.

METHODS

The hemodynamic effects of dobutamine (5 to 20 microg/kg/min intravenously) and enoximone (0.5 to 2 mg/kg intravenously) were assessed by pulmonary artery catheterization in 29 patients with chronic HF before and after 9 to 12 months of treatment with metoprolol or carvedilol at standard target maintenance oral doses. Hemodynamic studies were performed after >/=12 h of wash-out from all cardiovascular medications, except the beta-blockers that were administered 3 h before the second study.

RESULTS

Compared with before beta-blocker therapy, metoprolol treatment decreased the magnitude of mean pulmonary artery pressure (PAP) and pulmonary wedge pressure (PWP) decline during dobutamine infusion and increased the cardiac index (CI) and stroke volume index (SVI) response to enoximone administration, without any effect on other hemodynamic parameters. Carvedilol treatment abolished the increase in heart rate, SVI, and CI and caused a rise, rather than a decline, in PAP, PWP, systemic vascular resistance, and pulmonary vascular resistance during dobutamine infusion. The hemodynamic response to enoximone, however, was maintained or enhanced in the presence of carvedilol.

CONCLUSIONS

In contrast with its effects on enoximone, carvedilol and, to a lesser extent, metoprolol treatment may significantly inhibit the favorable hemodynamic response to dobutamine. No such beta-blocker-related attenuation of hemodynamic effects occurs with enoximone.

Levosimendan: a unique approach to the treatment of heart failure

Levosimendan is one of the first agents of a new class of drugs known as calcium sensitizers. These drugs are believed to increase cardiac contractility by sensitizing cardiac myofibrils to calcium, and may therefore be of clinical benefit in the treatment of low-cardiac output states, particularly congestive heart failure. In addition to sensitizing troponin to intracellular calcium, levosimendan has been shown to inhibit phosphodiesterase III, which may contribute to its positive inotropic effect, and open adenosine triphosphate (ATP)-sensitive potassium channels (K(ATP)), which may produce vasodilation. Unlike currently available intravenous inotropes, levosimendan does not increase myocardial oxygen utilization, has not been shown to be proarrhythmic, and has been used effectively in the presence of beta-blocking medications. Levosimendan also has not been shown to impair ventricular relaxation, which was an initial concern with this class of drugs. Clinical studies of levosimendan have demonstrated short-term hemodynamic benefits of levosimendan over both placebo and dobutamine. While large-scale, long-term morbidity and mortality data are scarce, the Levosimendan Infusion versus Dobutamine in severe low-output heart failure (LIDO) study suggested a mortality benefit of levosimendan over dobutamine up to 180 days after treatment. Clinical studies comparing levosimendan with other positive inotropes, namely milrinone, are lacking. Levosimendan treatment appears to be well-tolerated, with the primary adverse events being headache and hypotension. No clinically significant drug-drug interactions have been reported with levosimendan to date. The clinical future of levosimendan will depend on the results of larger, ongoing clinical trials.

Positive inotropic drug infusions for patients with heart failure: current controversies and best practice

Patients who experience severe symptoms of heart failure and repeated hospitalizations for exacerbations may benefit from positive inotropic drug infusion therapy such as dobutamine or milrinone. This article provides an overview of inotropic drug delivery in the home including current controversies and best practices to ensure safe home care policies and practice.

Comparison of dobutamine-based and milrinone-based therapy for advanced decompensated congestive heart failure: Hemodynamic efficacy, clinical outcome, and economic impact

BACKGROUND

The use of parenteral positive inotropic agents still remains a major component of therapy for patients with advanced decompensated congestive heart failure (CHF). However, no consensus guidelines have been developed for the appropriate selection of a first-line inotropic therapy. We sought to compare the clinical outcome and economic cost of dobutamine-based and milrinone-based therapy in patients with acute exacerbation of CHF.

METHODS AND RESULTS

We retrospectively analyzed the outcome of 329 patients admitted to the heart failure unit with acute exacerbation of CHF. More patients were treated with dobutamine-based therapy (269/329, 81.7%) than with milrinone-based therapy (60/329, 18.3%). Both groups had similar baseline characteristics and similar hemodynamic profiles at baseline, with the exception of higher mean pulmonary arterial pressure in the milrinone group (47 mm Hg vs 42 mm Hg, P <.001). One hundred nine patients (40%) of the dobutamine group required parenteral nitroprusside for hemodynamic optimization compared with 11 patients (18%) in the milrinone group (P <.001). The use of parenteral nitroglycerin and dopamine was similar in both groups. There was no significant difference in the in-hospital mortality rate (dobutamine 7.8% vs milrinone 10%) or clinical outcome between the 2 groups. However, the average direct drug cost per patient was significantly reduced in the dobutamine group compared with the milrinone group ($45 +/- $10 vs $1855 +/- $350, P <.0001).

CONCLUSION

Dobutamine-based therapy is an attractive approach for the treatment of decompensated advanced heart failure, achieving comparable clinical efficacy to milrinone with a significantly reduced economic cost.

Chronic infusion of dobutamine and nitroprusside in patients with end-stage heart failure awaiting heart transplantation: safety and clinical outcome

BACKGROUND

in patients with severe heart failure additional therapeutic support with intravenous inotropic or vasodilator drugs is frequently employed in an attempt to obtain hemodynamic and clinical control. No data comparing the use and efficacy of chronic intravenous inotropic and vasodilator therapy in patients with advanced heart failure are available.

AIMS

we evaluated, in a group of patients with advanced heart failure undergoing chronic infusion with dobutamine or nitroprusside, in addition to optimized oral therapy, (1) the safety of chronic infusion, (2) the efficacy of both drugs in managing unloading therapy and (3) clinical outcome of the two therapeutic strategies.

METHODS

one hundred and thirteen patients receiving optimized oral therapy, in functional class III/IV with symptoms and signs of refractory heart failure and requiring additional pharmacological support with either intravenous dobutamine or nitroprusside were evaluated. Clinical and therapeutic management and clinical outcome of the two groups were considered.

RESULTS

dobutamine was administered for 12 h/day for 20+/-23 days at a dosage of 7+/-3 microg/kg/min to 43 patients. The mean dose of nitroprusside was 0.76+/-0.99 microg/kg/min. The mean duration of use of this drug, administered as a 12-h/day infusion was 22+/-38 days. Nitroprusside infusion allowed greater doses of short-term ACE-inhibitors to be used compared to pre-infusion (ACE-inhibitor dose: 55+/-30 mg/day vs. 127+/-30 mg/day P<0.0001) and during dobutamine infusion (ACE-inhibitor dose: 85+/-47 mg/day vs. 127+/-30 mg/day P<0.002). Nitroprusside unlike dobutamine significantly improved the NYHA functional class. Of the 113 patients, 109 (97%) had a cardiac event during a mean follow-up of 337+/-264 days. Forty-four patients required hospitalization for worsening congestive heart failure, 45/113 (39%) patients died during the follow-up and 27/113 (24%) patients had a heart transplant in status one. Hospitalization, because of worsening heart failure was less frequent in the nitroprusside than in the dobutamine subgroup [29/51 (57%) vs. 19/22 (86%) P<0.02]. The overall mortality was 28% (20/70) in the nitroprusside group and 58% (25/43) in the dobutamine group (odds ratio 0.33 CI 0.16 to 0.73 P<0.006). In the group treated with nitroprusside, heart transplantation in status one was performed in 16/33 patients (48%), while in the dobutamine group this was done in 11/14 patients (78%) (odds ratio 0.25 CI 0.06-1.02 P<0.06). There was a significant reduction in the combined end-point of mortality/heart transplantation in status one in patients treated with nitroprusside compared to those treated with dobutamine (36/70 (51%) vs. 36/43 (84%) - (odds ratio 0.34 CI 0.14-0.80 P<0.01). The incidence of adverse events in the patients treated with nitroprusside was similar to that in those treated with dobutamine (20% vs. 17% P=ns).

CONCLUSIONS

for patients awaiting heart transplantation chronic intermittent nitroprusside infusions are more effective and safer than dobutamine in relieving symptoms, facilitating unloading therapy management and improving survival. Whether chronic intermittent infusion of nitroprusside could represent a feasible medical strategy in out-patients with severe heart failure remains to be investigated.

Effects of dobutamine on critical capillary PO(2) and lactic acidosis threshold in patients with cardiovascular disease

BACKGROUND

Muscle capillary PO(2) has been found to reach a minimal value, ie, a critical capillary PO(2), in the midrange of work capacity in patients with cardiovascular disease. However, it is not known if the critical capillary PO(2) can be influenced by a change in blood flow response to exercise. This study was carried out to determine the effect of changing the blood flow response to exercise, using low-dose infusion of dobutamine, on muscle end-capillary PO(2) (as approximated by femoral vein PO(2)), lactate concentration, oxygen uptake (O(2)), and the relation among these variables.

METHODS

Eleven male patients with coronary artery disease performed an incremental exercise test on a cycle ergometer with and without continuous infusion of dobutamine, 6 microg/kg/min. Respiratory gas analysis was performed on a breath-by-breath basis; femoral vein blood was sampled every minute through a percutaneous catheter.

RESULTS

Dobutamine increased resting O(2) and O(2) at the lactic acidosis threshold (LAT) but not peak O(2). The femoral vein PO(2) rapidly decreased toward a minimal value with increasing work rate (O(2)) irrespective of the infusion of dobutamine. After reaching its nadir (critical PO(2)), femoral vein lactate began to increase without further decrease in PO(2). Infusion of dobutamine significantly increased femoral vein resting PO(2) (27.4 +/- 4.9 mm Hg vs 32.5 +/- 3.8 mm Hg) and critical PO(2) (20.5 +/- 1.5 mm Hg vs 21.9 +/- 1.7 mm Hg), but not the PO(2) at peak O(2) (22.1 +/- 3.3 mm Hg vs 22.0 +/- 2.9 mm Hg).

CONCLUSIONS

Infusion of dobutamine was found to raise the critical PO(2) and LAT but not peak O(2). These findings suggest that some of the acute increase in blood flow induced by dobutamine infusion benefits exercising muscle by increasing capillary PO(2), thereby delaying the onset of lactic acidosis.

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.

Outpatient cardiac infusion units: impact in elderly patients with refractory heart failure

BACKGROUND

The use of intermittent intravenous infusions of inotropic drugs is under evaluation in the management of patients with refractory heart failure.

OBJECTIVES

We investigated the impact of intermittent outpatient infusions of inotropes on hospital admissions, emergency room visits, functional class, and symptom-free interval after administration of inotropes to elderly patients with advanced heart failure symptoms.

METHODS

This retrospective analysis involved 24 elderly outpatients with a New York Heart Association class of III or IV and refractory heart failure symptoms.

RESULTS

Seven patients with class III heart failure (age 74A+/-4 years; left ventricular ejection fraction 27A+/-9%) and 17 patients of class IV (age 73A+/-4 years; LVEF 21A+/-10%) were included. Twenty patients were males. A total of 365 outpatient treatment sessions were administered, with 15A+/-9 sessions per patient (range, 6-43). Eleven patients improved and were discharged; seven patients died; three discontinued treatment; two patients remain on therapy; and one patient required continuous infusion. During this treatment, there were only three emergency room visits and six hospital admissions due solely to heart failure. Fourteen patients required no emergency room visits or hospitalization. Of the patients discharged from the program, the interval without heart failure symptoms ranged from 60-356 days, with an improvement in NYHA class from 3.5A+/-0.6 to 1.4A+/-0.5 and no emergency room visits or hospital admissions.

CONCLUSIONS

This type of therapy is well tolerated among elderly patients with refractory heart failure symptoms and its use deserves further investigation.

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.