Hemodynamic and neurohumoral effects of continuous infusion of levosimendan in patients with congestive heart failure

Levosimendan has an inhibitory effect on platelet function

Levosimendan enhances cardiac contractility by increasing myocyte sensitivity to calcium, and induces vasodilatation. Although studies have evaluated the efficacy of levosimendan in heart failure, it is not clear whether it might produce functional influence on platelet response. In this study, the effect of levosimendan on platelet aggregation was investigated. Platelet function tests were performed in 12 healthy male volunteers. Three concentrations of levosimendan solution were prepared that would result in 10, 25, and 45 ng/ml levosimendan concentrations in the blood similar to that observed after clinical therapeutic intravenous application of 0.05-0.1 microg/kg/min. Each concentration of levosimendan solution and a control diluent without levosimendan were incubated with whole blood at 37 degrees C. After incubation for 15 min, aggregation responses were evaluated with adenosine diphosphate (ADP) (5 and 10 microM) and collagen (2 and 5 microg/ml) in platelet-rich plasma. Preincubation with all dilutions of levosimendan inhibited aggregation of platelets induced by ADP and collagen significantly. Levosimendan also inhibited significantly the secondary wave of platelet aggregation induced by ADP. The results showed that there was a relationship between levosimendan concentration and inhibition of platelet aggregation. In conclusion, this study with an in vitro model showed that levosimendan had a significant inhibitory effect on platelets in clinically relevant doses.

[Role of Levosimendan in intensive care treatment of myocardial insufficiency]

Levosimendan is a calcium sensitizer that is currently in the focus of intensive care medicine because it may be superior to standard inotropic agents in the treatment of acute myocardial insufficiency. The effects of levosimendan mainly depend on three predominant mechanisms: 1) positive inotropic effect by increasing the sensitivity of cardiac myofilaments to calcium ions, 2) vasodilatory effect by stimulation of adenosine triphosphate-sensitive potassium channels and 3) inhibition of phosphodiesterase-III. In a large number of experimental and clinical studies further possible indications for levosimendan have been described, e.g. cardioprotection during ischemia, cardiogenic shock, septic myocardial insufficiency and pulmonary hypertension. This review article critically summarizes the current scientific and clinical knowledge about levosimendan, its pharmacologic characteristics, mechanisms of action as well as indications and potential risks.

Pharmacologic therapy of chronic heart failure

Over the past 2 decades, investigators have learned more about the pathophysiologic changes that occur in systolic and diastolic dysfunction. Ironically, in some cases, the biologic pathways that have protected the heart during acute dysfunction are the same pathways that cause progressive deleterious effects with chronic activation. In particular, it is the activation of the neurohormonal system that has a significant impact on disease progression. As a result, the neurohormonal system has provided a key target for pharmacologic therapy in patients with heart failure secondary to systolic dysfunction. These targets include the renin-angiotensin-aldosterone system as well as the sympathetic nervous system. Neurohormonal manipulation, however, is often ineffective in the pharmacologic therapy of patients with endstage heart failure, therefore other treatment strategies - including the use of inotropic agents to improve pump function and diuretics to control fluid balance are needed.

Clinical pharmacology of levosimendan

Levosimendan has been developed for the treatment of decompensated heart failure and is used intravenously when patients with heart failure require immediate initiation of drug therapy. It increases cardiac contractility and induces vasodilatation. The pharmacokinetics of levosimendan are linear at the therapeutic dose range of 0.05-0.2 microg/kg/minute. The short half-life (about 1 hour) of the parent drug, levosimendan, enables fast onset of drug action, although the effects are long-lasting due to the active metabolite OR-1896, which has an elimination half-life of 70-80 hours in patients with heart failure (New York Heart Association functional class III-IV). Although levosimendan is administered intravenously, it is excreted into the small intestine and reduced by intestinal bacteria to an amino phenolpyridazinone metabolite (OR-1855). This metabolite is further metabolised by acetylation to N-acetylated conjugate (OR-1896). The circulating metabolites OR-1855 and OR-1896 are formed slowly, and their maximum concentrations are seen on average 2 days after stopping a 24-hour infusion. The haemodynamic effects after levosimendan seem to be similar between fast and slow acetylators despite the fact that the enzyme N-acetyltransferase-2, which is responsible for the metabolism of OR-1855 to OR-1896, is polymorphically distributed in the population. Levosimendan reduces peripheral vascular resistance and has direct contractility-enhancing effects on the failing left ventricle. It also improves indices of diastolic function and seems to improve the function of stunned myocardium. Despite an improvement in ventricular function, levosimendan does not increase myocardial oxygen uptake significantly. An increase in coronary blood flow and a reduction in coronary vascular resistance have been observed. Levosimendan reduces plasma brain natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) levels substantially, and a decrease in plasma endothelin-1 has been observed. Levosimendan also exerts beneficial effects on proinflammatory cytokines and apoptosis mediators. The effects of a 24-hour levosimendan infusion on filling pressure, ventricular function and BNP, as well as NT-proBNP, last for at least 7 days.

Both levosimendan and dobutamine treatments result in significant reduction of NT-proBNP levels, but levosimendan has better and prolonged neurohormonal effects than dobutamine

Levosimendan and dobutamine are comparable inotropic drugs as regards their hemodynamic effects and clinical outcomes in decompensated heart failure (HF). The aim of this study was to compare the effects of levosimendan and dobutamine treatment on NT-proBNP levels in patients with decompensated HF. Forty-four patients with decompensated HF and ejection fraction <35% received either a 24-h infusion of levosimendan (n=26) or dobutamine (n=18). NT-proBNP was measured at baseline and 12 h, 24 h and 48 h after the initiation of drug infusion. NT-proBNP levels at baseline, 12 h, 24 h and 48 h were 16,879+/-2437, 16,004+/-2635, 12,881+/-2305 and 11,078+/-2092 pg/ml, respectively, in the levosimendan group and 16,031+/-3463, 15,908+/-3806, 12,271+/-3299 and 14,840+/-4009 pg/ml, respectively, in the dobutamine group. NT-proBNP decreased significantly at 24 h in response to both levosimendan and dobutamine treatment (p<0.01 and p<0.05, respectively) with no significant difference among the treatment groups. In the dobutamine group, NT-proBNP increased at 48 h (p=n.s. vs. baseline), in contrast, NT-proBNP reduction continued for up to 48 h in the levosimendan group (p<0.001 vs. baseline). Although not statistically different, a greater percentage of NT-proBNP reduction was observed with levosimendan treatment at both 24 h (-25+/-7% vs. -20+/-10%) and 48 h (-32+/-7% vs. -20+/-11%) compared to dobutamine. Both levosimendan and dobutamine treatments result in significant reduction of NT-proBNP levels at the end of the 24-h infusion. However, compared to dobutamine, levosimendan has better and prolonged effects on NT-proBNP levels in decompensated HF.

A 6-Month Follow-up of Intermittent Levosimendan Administration Effect on Systolic Function, Specific Activity Questionnaire, and Arrhythmia in Advanced Heart Failure

BACKGROUND

Levosimendan (LS) improves cardiac contractility without increasing myocardial oxygen demand. We administrated LS on a monthly intermittent 24-hour protocol and evaluated the clinical effect after 6 months in a randomized, open, prospective study.

METHODS AND RESULTS

Fifty patients (age 45-65 years) with LV systolic dysfunction and New York Heart Association (NYHA) III or IV were randomized in 2 groups. LS group (n = 25) was compared with a control group (n = 25) matched for sex, age, and NYHA class. LS was given monthly on a 24-hour intravenous protocol for 6 months. Patients were evaluated by specific activity questionnaire (SAQ) and echocardiography (ECHO) before and 3 to 5 days after last drug administration, whereas 24-hour Holter recording was performed before and during last drug administration. Patients in LS and control group had same baseline SAQ, ECHO, and Holter parameters. At the end of the study, a larger proportion of patients in the levosimendan group reported improvement in symptoms (dyspnea and fatigue) (65% versus 20% in controls, P < .01). After 6 months, the LS group had a significant increase in LV ejection fraction versus controls (28 +/- 7 versus 21 +/- 4 %, P = .003), LV shortening fraction (15 +/- 3 versus 11 +/- 3 %, P = .006) and a decrease in mitral regurgitation (1.5 +/- 0.8 versus 2.7 +/- 0.6, P = .0001). There was no increase in supraventricular or ventricular beats or supraventricular tachycardia and VT episodes in LS group, compared with controls. Two patients from the LS group died in the 6-month follow-up period, compared with 8 patients in the control group (8% versus 32%, P < .05).

CONCLUSIONS

A 6-month intermittent LS treatment in patients with decompensated advanced heart failure improved symptoms and LV systolic function.

Effects of Levosimendan on Quality of Life and Emotional Stress in Advanced Heart Failure Patients

AIM

Levosimendan improves central hemodynamics and symptoms in acutely decompensated chronic heart failure (CHF) patients. However, its effects on quality of life, emotional stress and functional capacity of patients with advanced CHF have not been properly investigated.

METHODS AND RESULTS

Sixty-three advanced CHF patients (NYHA III-IV, LVEF<30%) were randomized (2:1) to receive either a 24-h levosimendan infusion of 0.1 mug/kg/min or placebo. Questionnaires addressing quality of life [Kansas City Cardiomyopathy Questionnaire (KCCQ), functional and overall, Duke's Activity Status Index (DASI)] and emotional stress [Zung self-rating depression scale (SDS), Beck Depression Inventory (BDI)], as well as plasma BNP and 6-min walking distance (6MWT as a marker of exercise capacity) were assessed before treatment and at hospital discharge. A significant improvement in NYHA class (2.1 +/- 0.7 from 3.3 +/- 0.7, p < 0.01), 6 MWT (305 +/- 152 from 215 +/- 142 m, p < 0.01) and plasma BNP (598 +/- 398 from 1,078 +/- 756 pg/ml, p < 0.01) was observed post-treatment only in levosimendan-treated group. KCCQ functional (45 +/- 19 from 35 +/- 17%, p < 0.05) and overall (34 +/- 13 from 28 +/- 11%, p < 0.05), DASI (26 +/- 13 from 22 +/- 12, p < 0.05), Zung SDS (38 +/- 12 from 42 +/- 13, p < 0.01) and BDI (11 +/- 6 from 14 +/- 8, p < 0.05) scores also improved in levosimendan-treated patients, while remained unchanged in the placebo group. The hospital length stay was shorter in levosimendan group compared to placebo (3.2 +/- 1.7 versus 5.8 +/- 2.1 days, p < 0.01). Levosimendan-induced BNP reduction was significantly correlated with concomitant increase in 6MWT (r = 0.643, p < 0.001) as well as with the decrease of BDI (r = 0.30, p < 0.05) and Zung SDS (r = 0.25, p = 0.05).

CONCLUSION

Levosimendan seems to have a beneficial effect on quality of life, physical activity and emotional stress in advanced CHF patients, reducing concurrently hospitalization length.

Effects of levosimendan on myocardial infarct size and hemodynamics in a closed-chest porcine ischemia-reperfusion model

INTRODUCTION

Levosimendan is a positive inotropic drug with vasodilator action and proposed myocardioprotective properties. In a canine model, levosimendan increased coronary collateral flow and reduced myocardial infarct size (IS). We investigated the effect of levosimendan on IS and hemodynamics in the closed-chest porcine ischemia-reperfusion model, which is devoid of coronary collaterals.

METHODS

Infusion with levosimendan (0.2 microg/kg/min following a bolus of 24 microg/kg) or saline was initiated 30 min prior to ischemia in anaesthetized pigs (n = 10 in both groups). Balloon occlusion of the left anterior descending coronary artery for 45 min was followed by 2 1/2 h of reperfusion. Hemodynamics were monitored with a Swan-Ganz catheter and a left ventricular pressure micromanometer. Left ventricular systolic and diastolic function was estimated by dP/dt(max) and tau, respectively. Myocardial area at risk (AAR) and IS were assessed in vivo by myocardial perfusion imaging (MPI) and ex vivo by histopathology (fluorescein staining for AAR, tetrazolium staining for IS).

RESULTS

Prior to ischemia, levosimendan improved left ventricular systolic and diastolic function with coincident preload and afterload reduction. Cardiac output increased by 10 +/- 4% (p = 0.04), dP/dt(max) by 15 +/- 5% (p = 0.01). Pulmonary capillary wedge pressure decreased by 18 +/- 3% (p = 0.04), tau by 11 +/- 2% (p = 0.001), and mean arterial pressure by 11 +/- 2% (p < 0.001). A similar trend was observed during ischemia-reperfusion. The ratio of IS/AAR was not reduced by levosimendan compared to saline as evaluated by histopathology (76 +/- 4% vs. 64 +/- 7%, p = 0.12) and by MPI (94 +/- 2% vs. 87 +/- 5%, p = 0.14).

CONCLUSION

Levosimendan improves hemodynamics but does not reduce IS in an ischemia-reperfusion model without coronary collaterals.

Classical inotropes and new cardiac enhancers

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

The Effects of Levosimendan in Cardiac Surgery Patients with Poor Left Ventricular Function

BACKGROUND

Patients with poor left ventricular function often require inotropic drug support immediately after cardiopulmonary bypass. Levosimendan improves cardiac function by a novel mechanism of action compared to currently available drugs. We hypothesized that, in patients with severely compromised ventricular function, the use of levosimendan would be associated with better postoperative cardiac function than with inotropic drugs that increase myocardial oxygen consumption.

METHODS

Thirty patients with a preoperative ejection fraction < or =30% scheduled for elective cardiac surgery with cardiopulmonary bypass were randomized to two different inotropic protocols: milrinone 0.5 microg [corrected] x kg(-1) x min(-1) or levosimendan 0.1 microg [corrected] x kg(-1) x min(-1), started immediately after the release of the aortic crossclamp. The treatment was masked to the observers. All patients received dobutamine 5 microg [corrected] x kg(-1) x min(-1).

RESULTS

Stroke volume was similar between groups initially after surgery, but it declined 12 h after surgery in the milrinone group but not in the levosimendan group (P < 0.05 between groups) despite similar filling pressures. Total dose, duration of inotropic drug administration and norepinephrine dose were lower in the levosimendan group than in the milrinone group (P < 0.05). The duration of tracheal intubation was shorter in the former group compared with the milrinone group (P = 0008). Three patients in the milrinone group but none in the levosimendan group died within 30 days of surgery.

CONCLUSION

In cardiac surgery patients with a low preoperative ejection fraction, stroke volume was better maintained with the combination of dobutamine with levosimendan than with the combination of dobutamine with milrinone.

A review of levosimendan in the treatment of heart failure

Heart failure is a relatively important public health problem due to its increasing incidence, poor prognosis, and frequent need of re-hospitalization. Intravenous positive inotropic agents play an important role in treating acute decompensation of patients with heart failure due to left ventricular systolic dysfunction. Although frequently used, the inotropic agents β-adrenergic agonists and phosphodiesterase inhibitors seem effective for improving symptoms in the short term; it has been shown that they increase morbidity and mortality by elevating intracellular cyclic adenosine monophosphate (cAMP) and calcium levels. Levosimendan is a new positive inotropic agent having ATP-dependent potassium-channel-opening and calcium-sensitizing effects. In studies on its effects without increasing intracellular calcium concentrations and on its effects that depend on available intracellular calcium levels, it has been shown to have favorable characteristics different from those of current inotropic agents, which exert their effects by increasing calcium concentrations. This study aims to review other important studies about levosimendan by revealing the underlying mechanisms of its activity, efficiency, and safety.

The use of levosimendan in comparison and in combination with dobutamine in the treatment of decompensated heart failure

Levosimendan is a new calcium sensitizer with inotropic and vasodilatory actions mediated by the sensitization of contractile proteins to calcium, opening of potassium channels and inhibition of phosphodiesterase-3. Its alternative mechanisms of action to those of other traditional inotropes provide a new approach in the management of decompensated heart failure. In contrast to dobutamine, levosimendan does not increase myocardial oxygen demand and, therefore, it is thought to have a lower potential to induce increases in myocardial ischemia and cardiac arrhythmias. The commonly used inotropic agent dobutamine increases myocardial contractility at the expense of increased myocardial oxygen consumption and, therefore, it can result in poor outcomes. Although dobutamine may also have favorable hemodynamic and symptomatic effects, levosimendan has been shown to be superior to dobutamine in increasing cardiac output and decreasing pulmonary capillary wedge pressure in patients with decompensated heart failure. In the presence of concomitant beta-blocker therapy, these favorable effects were present or even more pronounced during treatment with levosimendan, but not dobutamine. However, the mortality benefit of levosimendan observed in earlier trials has not been confirmed in recent, larger clinical trials. A distinct advantage of levosimendan over dobutamine is its prolonged hemodynamic effects, which last for up to 7-9 days. There are more data on the safety of levosimendan in ischemic patients than with any other inotropic drug and, therefore, levosimendan seems to be safe and effective in patients with ischemic heart disease when used at the recommended doses. Despite advances in heart failure therapy, many patients experience clinical deterioration, or do not respond to a single inotropic drug. Increasing evidence suggests the use of levosimendan in combination with dobutamine in patients with decompensated heart failure that is refractory to dobutamine alone.

Successful Use of Levosimendan in a Patient During Cardiopulmonary Bypass

Levosimendan (LS) is a novel calcium sensitizer drug that enhances cardiac contractility without increasing myocardial oxygen consumption, and induces vasodilatation. Positive inotropic support is routinely used for weaning from cardiopulmonary bypass circulation in patients with reduced left ventricular function. This case report represents the successful usage of LS for weaning from cardiopulmonary bypass circulation after coronary artery bypass surgery. Levosimendan infusion was started at the sixth hour of cardiopulmonary bypass circulation. There was a dramatic increase in cardiac output 20 minutes after LS infusion, and weaning from cardiopulmonary bypass circulation was achieved. We suggest that LS enhances cardiac performance during and after cardiopulmonary bypass, and can be useful for patients who are unable to be weaned from cardiopulmonary bypass.

Levosimendan improves right ventriculovascular coupling in a porcine model of right ventricular dysfunction*

OBJECTIVE

Experimental data suggest that levosimendan has pulmonary vasodilatory properties which, in combination with its positive inotropic effects, would render it particularly attractive for the treatment of right ventricular dysfunction. To test this hypothesis, we developed an experimental model of right ventricular failure and analyzed the effects of levosimendan on ventriculovascular coupling between the right ventricle and pulmonary artery (PA).

DESIGN

Prospective, randomized, placebo-controlled animal study.

SETTING

University hospital laboratory.

SUBJECTS

Fourteen pigs (mean weight 36 +/- 1 kg).

INTERVENTIONS

Pigs were instrumented with biventricular conductance catheters, a PA and right coronary artery flow probe, and a high-fidelity pulmonary pressure catheter. Right ventricular dysfunction was induced by repetitive episodes of ischemia/reperfusion in the presence of temporary PA constriction. Pigs were randomly assigned to receive levosimendan (120 mg/kg/hr [corrected] for 10 mins followed by continuous infusion of 60 mg/kg/hr [corrected] for 45 mins) or the placebo (control).

MEASUREMENTS AND MAIN RESULTS

Induction of right ventricular dysfunction resulted in a 42% decrease in contractility (reduction in slope of preload recruitable stroke work [Mw] from 2.5 +/- 0.4 to 1.8 +/- 0.5 mW x sec x mL(-1); p = .02) and a 60% increase in right ventricular afterload (effective pulmonary arterial elastance [PA-Ea] from 0.6 +/- 0.1 to 1.0 +/- 0.3 mm Hg x mL(-1); p < .01). Right ventriculovascular coupling, as assessed by the quotient of right ventricular end-systolic elastance (E(max)) over PA-Ea, decreased from 1.23 +/- 0.38 to 0.64 +/- 0.21 (p = .03). Treatment with levosimendan improved right ventricular contractility (Mw from 1.9 +/- 0.4 to 2.9 +/- 0.5 mW x sec x mL(-1); p < .01), lowered right ventricular afterload (PA-Ea from 1.1 +/- 0.3 to 0.8 +/- 0.3 mm Hg x mL(-1); p = .02), and restored right ventriculovascular coupling to normal values (E(max)/PA-Ea = 1.54 +/- 0.51). Levosimendan also significantly increased coronary blood flow and left ventricular contractility (Mw from 7.2 +/- 3.3 to 9.5 +/- 2.9 mW x sec x mL(-1); p = .01) but did not affect biventricular diastolic function.

CONCLUSIONS

In an experimental model of acute right ventricular dysfunction, levosimendan improved global hemodynamics and optimized right ventriculovascular coupling via a moderate increase in right ventricular contractility and a mild reduction of right ventricular afterload.

Levosimendan: beyond its simple inotropic effect in heart failure

Classic inotropic agents provide short-term haemodynamic improvement in patients with heart failure, but their use has been associated with poor prognosis. A new category of inotropic agents, the Ca(2+) sensitizers, may provide an alternative longer lasting solution. Levosimendan is a relatively new Ca(2+) sensitizer which offers haemodynamic and symptomatic improvement by combining a positive inotropic action via Ca(2+) sensitization and a vasodilatory effect via adenosine triphosphate(ATP)-sensitive K(+) (K(ATP)), Ca(2+)-activated K(+) (K(Ca)(2+)) and voltage-dependent K(+) (K(V)) channels activation. Levosimendan also seems to induce a prolonged haemodynamic improvement in patients with heart failure as a result of the long half-life of its active metabolite, OR-1896. Furthermore, there is also evidence that levosimendan may have additional antiinflammatory and antiapoptotic properties, affecting important pathways in the pathophysiology of heart failure. Despite the initial reports for a clear benefit of levosimendan on short- and long-term mortality in patients with severe heart failure, the results from the recent clinical trials are rather disappointing, and it is still unclear whether it is superior to dobutamine in affecting survival of patients with severe heart failure. In conclusion, levosimendan is a promising agent for the treatment of decompensated heart failure. As further to its positive inotropic effect, it affects multiple pathways with key roles in the pathophysiology of heart failure. The results of the ongoing trials examining the effect of levosimendan on mortality in patients with heart failure will hopefully resolve the controversy as to whether levosimendan is superior to classic inotropic agents for the treatment of severe heart failure.

Review of current and investigational pharmacologic agents for acute heart failure syndromes

Acute heart failure syndromes (AHFS) are a major public health problem and present a therapeutic challenge to clinicians. Commonly used agents in the treatment of AHFS include diuretics, vasodilators (eg, nitroglycerin, nitroprusside, nesiritide), and inotropes (eg, dobutamine, dopamine, milrinone). Patients admitted to hospital with AHFS and low cardiac output state (AHFS/LO) represent a subgroup with very high inhospital and postdischarge mortality rates. Most of these patients require intravenous inotropic therapy. However, the use of current intravenous inotropes has been associated with risk for hypotension, atrial and ventricular arrhythmias, and possibly increased postdischarge mortality, particularly in those with coronary artery disease. Consequently, there is an unmet need for new agents to safely improve cardiac performance (contractility and/or active relaxation) in this patient population. This article reviews a selection of current and investigational agents for the treatment of AHFS, with a main focus on the high-risk patient population with AHFS/LO.

Severe stunned myocardium after lightning strike

OBJECTIVE

To report the development of myocardial stunning and severe heart failure after lightning strike with total recovery of function.

DESIGN

Case report.

SETTING

Coronary care unit at Medica Sur Clinic, Mexico.

PATIENT

A 42-yr-old woman who was hit by lightning developed rapid and progressive hemodynamic deterioration manifested by cardiogenic shock that required invasive monitoring. Twenty-four hours after the strike, intravenous levosimendan and intra-aortic balloon pump were initiated because the patient demonstrated no significant response to management with conventional inotropic agents. Two days later, echocardiographic signs of systolic and diastolic dysfunction improved markedly. Dual-isotope-imaging myocardial perfusion testing with technetium-99m-sestamibi and thallium-201, performed 9 days after admission, showed normal perfusion and normal left ventricular systolic function. The patient exhibited complete recovery of function. The exact mechanism of abnormal contractility in the absence of direct electrofulguration is unknown but may be explained by release of oxygen free radicals, proteolysis of the contractile apparatus, and cytosolic overload of intracellular calcium, followed by reduced myofilament sensitivity to calcium. These abnormalities are consistent with stunned myocardium.

CONCLUSIONS

Lightning strike may cause serious contractile dysfunction in the absence of irreversible myocardial injury, but the exact mechanism of this phenomenon remains unknown. We propose that lighting strike can cause myocardial stunning resulting in severe but reversible left ventricular dysfunction. The patient's recovery was facilitated by support treatment including administration of levosimendan, which increases the intracellular sensitivity to calcium, a mechanism disturbed in patients with myocardial stunning.

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.

Levosimendan cardioprotection reduces the metabolic response during temporary regional coronary occlusion in an open chest pig model

BACKGROUND

Inotropic and myocardial anti-ischemic effects have been demonstrated with levosimendan. The comparison of levosimendan started before an ischemia-reperfusion event as compared with levosimendan started during ischemia has not been studied.

METHODS

In anesthetized pigs, a major branch of the circumflex artery was completely occluded for 30 min and then reperfused. The metabolism in the ischemic myocardium and in non-ischemic control myocardium was studied with microdialysis concomitantly with monitoring of global hemodynamics and coronary artery flow in the chosen artery. In the protection group (PRO, n= 6), a levosimendan infusion was started 30 min before coronary artery occlusion, and in the treatment group (TRE, n= 6), a levosimendan infusion was started 10 min after the coronary artery occlusion with a loading dose of 13.3 microg/kg followed by an infusion of 0.67 microg/kg/min. A two-way repeated measures ANOVA completed with Bonferroni's multiple comparison procedure was applied to the data. A P < 0.05 was considered significant.

RESULTS

During the ischemic period, the cardiac output and contractility (dp/dt(max)) were higher in the PRO as compared with the TRE and the systemic vascular resistance was lower. The myocardial microdialysate glucose concentration in the ischemic area during ischemia was higher in the PRO as compared with the TRE, and the lactate/pyruvate ratio and the lactate concentration were lower. The differences in the metabolites persisted into the first 10 min of reperfusion. No differences were found for the non-ischemic areas.

CONCLUSION

Levosimendan used throughout myocardial ischemia-reperfusion might have a cardioprotective affect on the response to myocardial ischemia as compared with levosimendan started during the ischemia.

Effect of levosimendan on ventricular arrhythmias and prognostic autonomic indexes in patients with decompensated advanced heart failure secondary to ischemic or dilated cardiomyopathy

Positive inotropes used for the treatment of heart failure have been arrhythmogenic. Levosimendan is a novel calcium sensitizer with vasodilating properties and a complex mechanism of action. Its effect on ventricular arrhythmias and 24-hour Holter electrocardiographically derived prognostic autonomic nervous system-related markers, because it occurs in parallel with changes in cardiac function and neurohormonal response, has not been systematically assessed. Forty-five patients (mean age 65 +/- 1.3 years) with heart failure refractory to conventional therapy and a mean ejection fraction of 23 +/- 1.2%, randomized to levosimendan or placebo, were studied. After Holter electrocardiographic recording, 1 drug was infused for 24 hours (levosimendan at a dose of 0.1 mug/kg/min). During this period, another Holter recording was performed to assess changes in ventricular arrhythmogenesis, 24-hour heart rate variability indexes, QTc, QT variability, and QT/RR slope. Clinical evaluation, echocardiography, and B-type natriuretic peptide measurements were performed at baseline and after treatment. After levosimendan, clinical and echocardiographic improvement was observed, associated with beneficial neurohormonal modulation (mean B-type natriuretic peptide level after levosimendan 668 +/- 108 vs 1,009 +/- 122 pg/ml at baseline, p <0.05). Episodes of nonsustained ventricular tachycardia increased with levosimendan (21.9 +/- 9.6 vs 3.0 +/- 1.2, p <0.05). Levosimendan and placebo exerted a neutral effect on all autonomic markers assessed. In conclusion, levosimendan at low doses increases nonsustained ventricular arrhythmias, without affecting Holter-derived, prognostically significant autonomic markers. At the same time, it is associated with improvements in cardiac function and neurohormonal response. These findings may have important clinical and prognostic implications.

The confounding issue of comorbid renal insufficiency

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

Effects of levosimendan versus dobutamine on pressure load-induced right ventricular failure*

OBJECTIVE

A transient increase in pulmonary arterial (PA) pressure can persistently depress right ventricular (RV) contractility. We investigated the effects of dobutamine and levosimendan on RV-PA coupling in this model of RV failure.

DESIGN

Prospective, controlled, randomized animal study.

SETTING

University research laboratory.

SUBJECTS

Fifteen anesthetized dogs.

INTERVENTIONS

Transient (90-min) PA constriction to induce persistent RV failure. Random assignment to dobutamine 5 and 10 microg/kg/min or levosimendan 12 microg/kg for 10 mins followed by 0.1 and 0.2 microg/kg/min.

MEASUREMENTS AND MAIN RESULTS

We measured PA distal resistance and proximal elastance by pressure-flow relationships and vascular impedance. We measured RV contractility by the end-systolic pressure-volume relationship (Ees), PA effective elastance by the end-diastolic to end-systolic relationship (Ea), and RV-PA coupling efficiency by the Ees/Ea ratio. PA constriction persistently increased PA resistance and elastance, increased Ea from 0.95 +/- 0.07 to 3.01 +/- 0.28 mm Hg/mL, decreased Ees from 1.17 +/- 0.09 to 0.58 +/- 0.07 mm Hg/mL, and decreased Ees/Ea from 1.26 +/- 0.09 to 0.22 +/- 0.03 (p < .05). Dobutamine did not affect pulmonary hemodynamics, markedly increased RV contractility, and improved RV-PA coupling. Levosimendan decreased PA resistance and elastance, increased RV contractility, and restored RV-PA coupling. Compared with dobutamine, levosimendan decreased RV afterload and therefore better restored RV-PA coupling at similar inotropic state.

CONCLUSIONS

A transient increase in PA pressure persistently worsens PA hemodynamics, RV contractility, RV-PA coupling, and cardiac output. Levosimendan restores RV-PA coupling better than dobutamine because of similar inotropic effects and additional pulmonary vasodilatory effects.

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.

Pharmacologic treatment of heart failure due to ventricular dysfunction by myocardial stunning: potential role of levosimendan

The treatment of heart failure continues to pose a real challenge for clinicians. This condition is sometimes reversible and therapy should therefore pursue this outcome. In the context of coronary ischemic syndromes, myocardial stunning can cause heart failure and even cardiogenic shock, with important prognostic repercussions. Myocardial stunning is mainly due to calcium overload in the cytosol of myocardial cells, the loss of myofilaments and their reduced sensitivity to calcium. Enhanced immune activation with inflammatory phenomena also plays an important role in the pathophysiology of cardiac dysfunction. Increasing evidence has shown that the myocardial ATP-dependent potassium channel (K(ATP)) plays an important role in many myocardial cell functions and that it is involved in ischemia-reperfusion injury and myocardial stunning. K(ATP) is thus considered a therapeutic target in this setting. Currently used inotropic drugs improve contractility by increasing intracellular concentrations of free calcium, but they increase myocardial consumption of energy and even produce arrhythmia; therefore, in this clinical context, they do not seem to be 'pathophysiologically correct' drugs. Levosimendan, a new calcium-sensitizing agent, increases contractility by enhancing the sensitivity of myofilaments to calcium by binding to the C cardiac troponin in cardiac muscle in a calcium-dependent way. Levosimendan also exerts a coronary and systemic vasodilatory effect through its K(ATP) channel-opening properties and may exert other cardioprotective actions through this mechanism. Levosimendan produces positive hemodynamic effects without increasing myocardial oxygen demand or causing arrhythmias. Intravenous levosimendan is generally well tolerated and has been approved by several European countries, and recently recommended in European Society of Cardiology guidelines, as inotropic therapy for the short-term treatment of acute severe decompensated heart failure in adults. Randomized, double-blind trials have shown that levosimendan is not only more clinically and hemodynamically effective but also that it significantly reduces morbidity and mortality when compared with dobutamine or placebo. Clinical trials addressing the use and efficacy of intravenous levosimendan in acute heart failure in patients with systolic dysfunction or cardiogenic shock due to myocardial stunning are scarce. Beneficial effects on myocardial contractility in patients with myocardial stunning have only been shown in small clinical trials. A positive experience with levosimendan in a small series of patients with cardiogenic shock complicating ST-elevation myocardial infarction suggests that the use of this drug in cardiogenic shock should be further evaluated.

Future pharmacologic agents for treatment of heart failure in children

The addition of new agents to the armamentarium of treatment options for heart failure in pediatric patients is exciting and challenging. Administration of these therapies to pediatric patients will require careful scrutiny of the data and skilled application. Developmental changes in drug metabolism, excretion, and distribution are concerning in pediatric patients, and inappropriate evaluation of these parameters can have disastrous results. Manipulation of the neurohormonal pathways in heart failure has been the target of most recently developed pharmacologic agents. Angiotensin receptor blockers (ARBs), aldosterone antagonists, beta-blockers, and natriuretic peptides are seeing increased use in pediatrics. In particular, calcium sensitizing agents represent a new frontier in the treatment of acute decompensated heart failure and may replace traditional inotropic therapies. Endothelin receptor antagonists have shown benefit in the treatment of pulmonary hypertension, but their use in heart failure is still debatable. Vasopressin antagonists, tumor necrosis factor inhibitors, and neutral endopeptidase inhibitors are also targeting aspects of the neurohormonal cascade that are currently not completely understood. The future of pharmacologic therapies will include pharmacogenomic studies on new and preexisting therapies for pediatric heart failure. The education and skill of the practitioner when applying these agents in pediatric heart failure is of utmost importance.

Myocardial regulatory proteins and heart failure

Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are considered to be the most specific and sensitive biochemical markers of myocardial damage. Troponins have been studied in a wide range of clinical settings, including heart failure; however, there are few data on the role of regulatory proteins in the pathogenesis of heart failure, although a few interesting hypotheses have been proposed. A considerable body of evidence favours the view that alteration of the myocardial thin filament is the primary event leading to defective contractility of the failing myocardium, while the changes in Ca(2+) handling are a compensatory response. A better understanding of the role of regulatory proteins under different physiological and pathological conditions could lead to new therapeutic approaches in heart failure. Recently, calcium sensitisation has been proposed as a novel method by which cardiac performance may be enhanced via an increase in the affinity of troponin C for calcium but without affecting intracellular calcium concentration. To date, the only calcium sensitizer used in clinical practice is levosimendan.

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 in Cardiac Surgery: Current Best Available Evidence

Recent upsurge in referral of patients with high perioperative risk or compromised left ventricular function for cardiac surgery has lead to an increasing use of pharmacologic support in the form of vasodilator and inotropic therapy to achieve improvement of tissue perfusion in the perioperative period or to support weaning from cardiopulmonary bypass. Traditionally, perioperatively used inotropic agents, epinephrine, dobutamine, and milrinone, are limited by significant increases in myocardial oxygen consumption, proarrhythmia, or neurohormonal activation. Levosimendan, a new inodilator for the treatment of decompensated heart failure, has also shown promise in elective therapy of cardiac surgical patients with high perioperative risk or compromised left ventricular function, as well as in rescue therapy of patients with difficult weaning from cardiopulmonary bypass. This review article briefly discusses the pharmacology of levosimendan and evaluates current best available evidence to assess the safety and efficacy of levosimendan usage in cardiac surgery.

The myofilament force-calcium relationship as a target for positive inotropic therapy in congestive heart failure

To-date positive inotropic therapy in the treatment of congestive heart failure has resulted in adverse effects on long term survival. These agents increase calcium cycling through beta-adrenergic stimulation or phosphodiesterase inhibition. An alternative method of producing positive inotropy is to increase the myofilament sensitivity to calcium. This can occur at several levels within the myofilament, and has potential benefits with respect to avoiding increased calcium cycling and producing a more favourable energy efficient positive inotropy. A potential adverse effect of increasing calcium sensitivity is slowed relaxation and diastolic dysfunction. We have learnt a considerable amount about the function of specific sites within the myofilament by the use of genetically engineered mouse models, which have shown diverse effects of various myofilament sites on global left ventricular function. Levosimendan is a novel inotropic agent that has several mechanisms of action including calcium sensitization, and is undergoing clinical trials at present. This review article will provide a comprehensive molecular, biophysical and physiological insight into the concepts underlying the myofilament force-calcium relationship and its potential as a target for positive inotropic therapy in heart failure.

Duration of the beneficial effects of levosimendan in decompensated heart failure as measured by echocardiographic indices and B-type natriuretic peptide

Levosimendan is effective in the treatment of decompensated heart failure. The beneficial effects of a single dose of levosimendan last much longer than those of other inotropes. However, the exact duration of the beneficial effects is unknown. We prospectively determined the duration of the cardiac effects, as measured by echocardiography, of levosimendan (LS) following a 24-hour infusion regimen in patients with decompensated heart failure (DHF). The effects of LS on plasma B-type natriuretic peptide (BNP) were also examined. Twenty patients with DHF displaying (1) deteriorating symptoms despite optimal oral therapy, (2) left ventricular ejection fractions (LVEF) < 35%, and (3) cardiac indices of < 2.5 L/m/min received 24 hours of LS infusion. Echocardiography and BNP measurements were performed pre- and postinfusion and were reassessed on days 7, 30, and 90. Left ventricular systolic function indices (cardiac output and LVEF), LV filling pressure indices, and right ventricular systolic function indices all improved following LS treatment. Most of these improvements were sustained for at least 7 days (P < 0.05) and returned to baseline by day 30 postinfusion and remained so on day 90. Plasma BNP also displayed the same pattern of transient improvements. In conclusion, LS transiently improved the cardiac function, and the effects lasted for at least 7 days after discontinuation of infusion. Most effects, except LVEF, were not significantly different from baseline on day 30.

Short-term effects of levosimendan and prostaglandin E1 on hemodynamic parameters and B-type natriuretic peptide levels in patients with decompensated chronic heart failure

BACKGROUND

Both levosimendan and prostaglandin E1 (PGE1) have beneficial effects on hemodynamic parameters and outcome compared to dobutamine in decompensated chronic heart failure (CHF).

AIMS

We compared short-term effects of levosimendan versus PGE1 on hemodynamic parameters and B-type natriuretic peptide levels (BNP) in patients with decompensated CHF.

METHODS AND RESULTS

73 patients (cardiac index < 2.5 L/min/m2, pulmonary capillary wedge pressure (PCP) >15 mmHg) with decompensated CHF were randomised to treatment with either a 24 h-infusion of levosimendan (n=38) or a chronic infusion of PGE1 (n = 35). Hemodynamic parameters and BNP were measured at baseline, 24 and 48 h, BNP levels were also measured after 1 week. Baseline characteristics including concomitant medication were similar in both groups. Levosimendan and PGE1 increased cardiac output (CO) after 24 and 48 h. Levosimendan increased CO twice as much as PGE1 (24 h: Levosimendan +1.1 +/- 0.1 L/min, PGE1 +0.6 +/- 0.1 L/min, p < 0.001). Both drugs produced a comparable reduction in PCP and pulmonary artery pressure after 24 and 48 h. Levosimendan decreased BNP by 28% after 24 h and 22% after 48 h, but effects disappeared after 1 week. In contrast, PGE1 decreased BNP by 15% after 48 h (no change at 24 h), but a decrease of 20% was sustained at 1 week.

CONCLUSIONS

The differential beneficial effects of levosimendan (greater increase in CO) and PGE1 (sustained decrease in BNP) may have a potential impact on clinical outcome.

Calcium sensitizer agents: a new class of inotropic agents in the treatment of decompensated heart failure

The clinician's primary objective in treating a patient with decompensated heart failure is rapid and effective stabilization. This goal often is achieved through the use of inotropic support. Classic inotropic agents (beta-adrenergic agonists and phosphodiesterase III inhibitors) can provide short-term hemodynamic benefits, but their long-term use has been correlated with poor survival rates. Calcium sensitizers comprise a new drug class that offers hemodynamic and symptomatic improvements without increasing cAMP and intracellular calcium concentrations. These agents enhance contractility without a concurrent increase in the risk of cardiac events and thus represent a significant improvement over classic positive inotropic agents. Levosimendan is the most potent calcium sensitizer to date, exhibiting a unique dual mechanism of action that combines a positive inotropic action mediated via calcium sensitization and a vasodilator property via ATP-dependent potassium channels. Available clinical data suggest that calcium sensitizer agents represent a promising class of inotropic agents in a field that has seen few advances in recent decades.

New Directions in the Medical Management of Heart Failure

Like the introduction of digitalis more than 200 years ago, novel medical therapies today have the potential to significantly alter the course of heart failure (HF) and save thousands of lives. This review outlines new directions in HF medical management beyond the foundation of neurohormonal blockade. Furthermore, the role of novel risk factors in HF such as chronic renal insufficiency, anemia, and sleep apnea present tantalizing therapeutic targets to extend the morbidity and mortality benefits of current therapies. The course of time will tell which of these risk factors and therapies can hold promise, given the recent litany of negative trials in the HF arena. Advancements in molecular and genetic techniques have allowed us to begin to consider patient specific therapies and lay the groundwork for even further improvements in treatment of symptomatic HF. Finally, advances in telemedicine and device technology will allow the clinician to remotely monitor useful clinical parameters such as heart rate variability and pulmonary filling pressures to make more informed clinical decision-making and improve outcomes.

Levosimendan for the treatment of acute heart failure syndromes

Levosimendan is a novel calcium-sensitising agent that has been shown to have beneficial inotropic, metabolic and vasodilatory effects in the treatment of acute and advanced chronic heart failure. Levosimendan binds to troponin-C in cardiomyocytes and, thereby, improves cardiac contractility without disturbing the metabolic status of the heart and increasing myocardial oxygen demand or provoking fatal cardiac arrhythmias. Levosimendan also opens ATP-sensitive potassium channels, causing peripheral arterial and venous dilatation, and increasing coronary flow reserve. When it is given as a short-term therapy, levosimendan enhances cardiac output, reduces systemic vascular resistance and lowers pulmonary capillary wedge pressure. Clinical outcomes were significantly reduced in decompensated or postmyocardial infarction heart failure patients who received levosimendan, compared with those on dobutamine or placebo. Recent investigations focusing on the anti-inflammatory and antiapoptotic actions of levosimendan in the failing heart indicate that improvement of cardiac contractile performance is closely related with the drug-induced reduction of circulating pro-inflammatory cytokines and apoptosis inducers. The most common adverse effects of levosimendan treatment are hypotension and headache. Overall, levosimendan represents an effective and safe option for the treatment of decompensated heart failure patients.

Modern Management of Cardiogenic Pulmonary Edema

Cardiogenic pulmonary edema (CPE) is a life-threatening condition that is frequently encountered in standard emergency medicine practice. Traditionally, diagnosis was based on physical assessment and chest radiography and treatment focused on the use of morphine sulfate and diuretics. Numerous advances in diagnosis and treatment have been made, however. Serum testing for B-type natriuretic peptide (BNP) has improved the accuracy of diagnoses in these patients. Treatment should focus on fluid redistribution with aggressive preload and afterload reduction rather than simply on diuresis. Some specific medications and noninvasive positive pressure ventilation have been shown to be safe and rapidly effective in improving patients' symptoms and improve outcomes.

Treatment of cardiogenic shock with levosimendan in combination with β-adrenergic antagonists

Levosimendan, a calcium sensitizer, was used in combination with beta-adrenergic antagonists in a man aged 56 yr with cardiogenic shock, complicating acute myocardial infarction, who developed severe tachycardia after dobutamine administration. The patient's trachea was intubated, his lungs were ventilated, and he was started on dopamine 5 microg kg(-1) min(-1) and dobutamine 5 microg kg(-1) min(-1), titrated to a mean arterial pressure > or =65 mm Hg. He progressively became tachycardiac (>120 beats min(-1)) with a cardiac index (CI) of 1.4 litre min(-1) m(-2) despite adequate preload. Levosimendan 6 microg kg(-1) was administered intravenously over 10 min followed by a continuous infusion of 0.2 microg kg(-1) min(-1) for 24 h. Within 30 min, the patient's CI increased to 2.2 litre min(-1) m(-2), but the heart rate (HR) also increased from 142 to 155 beats min(-1). Esmolol 1 mg kg(-1) i.v. was administered with a consequent transient decrease in HR to 110 beats min(-1) without adverse haemodynamic effects; however, HR increased again shortly afterwards. Carvedilol 3.125 mg orally twice a day was then administered, and the dose was increased to 6.25 mg orally twice daily on the following day. Subsequently, HR decreased over time and both catecholamines were discontinued 14 h after starting levosimendan infusion. The trachea was extubated within 20 h and the patient was discharged to the ward on day 4 after admission. In conclusion, levosimendan in combination with a beta-adrenergic antagonist may have beneficial effects in patients with cardiogenic shock who exhibit tachycardia in response to inotropic agents.

Levosimendan: a novel inotropic agent for treatment of acute, decompensated heart failure

OBJECTIVE

To review the literature on a novel calcium sensitizer, levosimendan.

DATA SOURCES

Articles were identified through searches of MEDLINE (1966-June 2005), International Pharmaceutical Abstracts (1970-June 2005), and EMBASE (1992-June 2005) using the key words levosimendan, simendan, calcium sensitizer, calcium sensitiser, and congestive heart failure.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials and pharmacokinetic studies evaluating the safety and efficacy of levosimendan were selected.

DATA SYNTHESIS

Levosimendan 6-24 mug/kg intravenous bolus followed by a 24-hour continuous infusion of 0.05-0.2 microg/kg/min improved cardiac output and reduced pulmonary capillary wedge pressure in a dose-dependent manner. Dose-ranging and randomized clinical trials have demonstrated improvement in symptoms and hemodynamics and short-term survival outcomes in the treatment of acute, decompensated heart failure. Clinical trials evaluating retrospective mortality data and combined endpoints (mortality, rehospitalization) have demonstrated better outcomes with levosimendan compared with dobutamine. The incidence of hypotension with levosimendan is not significantly different than with dobutamine, but there is a dose-related increase in heart rate.

CONCLUSIONS

Levosimendan is useful in moderate to severe low-output heart failure in patients who have failed to respond to diuretics and vasodilators. Based on current studies, levosimendan appears to be a safe alternative to dobutamine for treatment of acute, decompensated heart failure. Prospective clinical trials are needed to confirm the effect of levosimendan on long-term survival and its role in heart failure in the setting of myocardial infarction.

Effects of Levosimendan on Restrictive Left Ventricular Filling in Severe Heart Failure

BACKGROUND

A restrictive pattern of left ventricular filling is often present in patients with severe heart failure. Although the hemodynamic effects of levosimendan have been studied, the effects of levosimendan on LV filling pattern have not been investigated.

METHODS

Pulsed-wave Doppler mitral (transthoracic) and pulmonary venous flow (transesophageal) velocity curves were recorded in 30 patients with a restrictive pattern of left ventricular filling with New York Heart Association class III or IV heart failure who had a documented left ventricular ejection fraction < 30% by echocardiography and received a 0.1 microg/kg/min infusion of levosimendan for 24 h.

RESULTS

Levosimendan caused significant (p < 0.001) increases in stroke volume (from 46 +/- 4 to 57 +/- 4 mL) and decreases in pulmonary capillary wedge pressure (from 21 +/- 1 to 15 +/- 1 mm Hg). The E wave decreased (from 96 +/- 7 to 71 +/- 5 cm/s), and the A wave increased (from 40 +/- 4 to 46 +/- 4 cm/s). Moreover, deceleration time was increased (from 112 +/- 7 to 189 +/- 14 ms). The S wave of pulmonary venous flow was increased (from 38 +/- 3 to 60 +/- 3 cm/s), and atrial reversal was decreased (from 36 +/- 2 to 29 +/- 2 cm/s). All changes were significant (p < 0.001). Using stepwise linear regression analysis, we found that the percentage changes of the early/late transmitral diastolic peak flow velocity (E/A) ratio and the percentage changes of the isovolumetric relaxation time were independent predictors of the increase in cardiac output. Furthermore, the percentage changes of the systolic/diastolic ratio and the percentage changes of the E/A ratio were independent predictors of the decrease in pulmonary capillary wedge pressure.

CONCLUSIONS

Treatment with levosimendan improved measures of left ventricular diastolic function. Consequently, left ventricular stroke volume was increased.

Randomized clinical trials with levosimendan

There are important unmet needs in the treatment of acute heart failure syndromes (AHFS). The unique dual mechanism of action of levosimendan suggests that this new agent may help fill some of these unmet needs. A review of randomized, controlled clinical trials with levosimendan demonstrated that it is well tolerated, and its use results in significantly reduced pulmonary capillary wedge pressure (PCWP) and increased cardiac output. Effects of levosimendan on PCWP and cardiac output are more pronounced than those observed with dobutamine. Levosimendan treatment is also associated with significantly improved clinical symptoms. Moreover, data from 3 trials indicate that levosimendan treatment was associated with improved 6-month survival compared with dobutamine treatment or placebo. Emerging data suggest that levosimendan is beneficial for patients with acute myocardial ischemia. Thus, early clinical indicators suggest that levosimendan may help prevent myocardial injury during hospitalization for AHFS and may be well suited for first-line therapy for AHFS.

Pharmacology of new agents for acute heart failure syndromes

Current therapies for acute heart failure syndromes (AHFS) target hemodynamics by decreasing congestion or increasing myocardial contraction. Several new agents for AHFS use novel mechanisms of action that focus on new treatment targets, such as those providing anti-ischemic and anti-stunning effects, blocking vasopressin receptors, or blocking endothelin-1 receptors. For example, levosimendan acts as a calcium sensitizer and adenosine triphosphate-dependent potassium (K(ATP)) channel opener that increases contraction, causes vasodilation, and provides cardioprotective effects. This is accomplished by its dual mechanism of action. Levosimendan binds to cardiac troponin C, thereby enhancing calcium myofilament responsiveness and increasing myocardial contraction without increasing intracellular calcium levels. Thus, contraction is increased with no significant increase in myocardial oxygen consumption. The opening of K(ATP) channels by levosimendan causes vasodilation and exerts anti-ischemic and anti-stunning effects on the myocardium. Other new agents target neurohormonal pathways. Tezosentan is an antagonist of endothelin-1 receptors A and B. By inhibiting endothelin-1 receptors, tezosentan may counteract the activities of endothelin-1, which include vasoconstriction, proarrhythmic activities, potentiation of other neurohormones, and mediation of increased vascular permeability. Tolvaptan is a vasopressin V2-receptor antagonist that functions as an aquaretic (ie, it increases urine volume and serum sodium with little or no sodium loss). Therefore, by using novel mechanisms of action, these agents may provide new opportunities for helping patients with AHFS.

European experience on the practical use of levosimendan in patients with acute heart failure syndromes

The novel calcium sensitizer and ATP-dependent potassium channel opener levosimendan has been introduced for routine use in several European countries. Recent reports on clinical experience confirm the positive hemodynamic results and beneficial clinical effects described in the initial dose-finding and randomized comparative therapeutic trials in patients with severe low-output heart failure. In addition, studies in small series of patients with cardiogenic shock after myocardial infarction and/or surgical interventions and post-interventional myocardial dysfunction (stunning) indicate that the inotropic and vasodilating actions of levosimendan may be of value in a wider range of indications. Dose recommendations, combination with other drugs, and potential side effects are discussed in this overview.

Overview of randomized clinical trials in acute heart failure syndromes

Acute heart failure syndromes (AHFS) are among the most frequent causes of hospitalizations in the United States and Europe. Despite current therapies, patients with AHFS have high readmission and mortality rates. The randomized, controlled clinical trial is the standard by which contemporary therapies are evaluated, yet this tool of clinical science only recently has been rigorously applied to the development of novel therapies for patients with AHFS. This review briefly discusses some of the challenges presented in designing a clinical trial of therapies for AHFS and to describe some of the recent trials with respect to these issues in established drugs (such as milrinone, dobutamine, nitroglycerin, nitroprusside, and nesiritide) that have been approved by the US Food and Drug Administration (FDA). Recent trials of current investigational agents, such as levosimendan (the Randomized Multicenter Evaluation of Intravenous Levosimendan Efficacy Versus Placebo in the Short-Term Treatment of Decompensated Heart Failure [REVIVE], the Calcium Sensitizer or Inotrope or None in Low-Output Heart Failure [CASINO] study, and the Survival of Patients with Acute Heart Failure in Need of Intravenous Inotropic Support [SURVIVE] trial), tezosentan (the Randomized Intravenous Tezosentan [RITZ] study and the Value of Endothelin Receptor Inhibition with Tezosentan in Acute Heart Failure Studies [VERITAS]), and tolvaptan (the Acute and Chronic Therapeutic Impact of a Vasopressin Antagonist in Congestive Heart Failure [ACTIV-CHF] study), are also discussed.