Levosimendan improves LV systolic and diastolic performance at rest and during exercise after heart failure

Acute and chronic effects of levosimendan in the ZSF1 obese rat model of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a syndrome characterized by impaired cardiovascular reserve in which therapeutic options are scarce. Our aim was to evaluate the inodilator levosimendan in the ZSF1 obese rat model of HFpEF. Twenty-week-old male Wistar-Kyoto (WKY), ZSF1 lean (ZSF1 Ln) and ZSF1 obese rats chronically treated for 6-weeks with either levosimendan (1 mg/kg/day, ZSF1 Ob + Levo) or vehicle (ZSF1 Ob + Veh) underwent peak-effort testing, pressure-volume (PV) haemodynamic evaluation and echocardiography (n = 7 each). Samples were collected for histology and western blotting. In obese rats, skinned and intact left ventricular (LV) cardiomyocytes underwent in vitro functional evaluation. Seven additional ZSF1 obese rats underwent PV evaluation to assess acute levosimendan effects (10 μg/kg + 0.1 μg/kg/min). ZSF1 Ob + Veh presented all hallmarks of HFpEF, namely effort intolerance, elevated end-diastolic pressures and reduced diastolic compliance as well as increased LV mass and left atrial area, cardiomyocyte hypertrophy and increased interstitial fibrosis. Levosimendan decreased systemic arterial pressures, raised cardiac index, and enhanced LV relaxation and diastolic compliance in both acute and chronic experiments. ZSF1 Ob + Levo showed pronounced attenuation of hypertrophy and interstitial fibrosis alongside increased effort tolerance (endured workload raised 38 %) and maximum O2 consumption. Skinned cardiomyocytes from ZSF 1 Ob + Levo showed a downward shift in sarcomere length-passive tension relationship and intact cardiomyocytes showed decreased diastolic Ca2+ levels and enhanced Ca2+ sensitivity. On molecular grounds, levosimendan enhanced phosphorylation of phospholamban and mammalian target of rapamycin. The observed effects encourage future clinical trials with levosimendan in a broad population of HFpEF patients.

[Comparative assessment of the effects of dobutamine and levosimendan on right ventricular ejection fraction in patients with biventricular heart failure]

Aim    The primary objective of this study was to comparatively assess the effects of levosimendan and dobutamine on RVEF, right ventricular diastolic function, and hormonal balance in patients with biventricular heart failure. The secondary objective was to investigate the relationship between the RVEF and the peak systolic velocity (Sa), an indicator of right ventricular systolic function, as measured by tissue Doppler echocardiography from the tricuspid annulus, and by the tricuspid annular plane systolic excursion (TAPSE).Material and Methods    The population of this cross-sectional, single-center, prospective study was comprised of 81 patients, who between December 2019 and January 2022, applied to the study health institution with diagnosis of ADHF. The study sample included 67 biventricular heart failure patients with left ventricular ejection fraction (LVEF) <35 % and RVEF <50 %, as measured by the ellipsoidal shell model, and who met the other study inclusion criteria. Of these 67 patients, 34 were treated with levosimendan, and 33 were treated with dobutamine. RVEF, LVEF, Sa, peak early (Ea) and peak late (Aa) annular velocities, Ea / Aa ratio, TAPSE, systolic pulmonary artery pressure (SPAP), n-terminal pro-brain natriuretic peptide (NT-pro BNP), and functional capacity (FC) were measured before treatment and at 48 hrs of treatment. The within group pre- and post-treatment differences (Δs) of these variables were compared.Results    RVEF, SPAP, and BNP, and FC significantly improved in both treatment groups (p<0.05 for all). Sa (p<0.01), TAPSE (p<0.01), LVEF (p<0.01), and Ea / Aa (p<0.05) improved only in the levosimendan group. The pre- and post-treatment Δs for RVEF, LVEF, SPAP, Sa, TAPSE, FC, and Ea / Aa were higher in the levosimendan group than in the dobutamine group (p<0.05 for all).Conclusion    Compared to dobutamine, levosimendan produced greater improvement in right ventricular systolic and diastolic function in patients with biventricular heart failure and in need of inotropic therapy support.

Management of Chronic Congestive Heart Failure Caused by Myxomatous Mitral Valve Disease in Dogs: A Narrative Review from 1970 to 2020

Simple Summary

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in dogs. The progression of the disease and the increasing severity of valvular regurgitation cause a volume overload of the left heart, leading to left atrial and ventricular remodeling and congestive heart failure (CHF). The treatment of chronic CHF secondary to MMVD in dogs has not always been the same over time. In the last fifty years, the drugs utilized have considerably changed, as well as the therapeutic protocols. Some drugs have also changed their intended use. An analysis of the literature concerning the therapy of chronic heart failure in dogs affected by this widespread degenerative disease is not available; a synthesis of the published literature on this topic and a description of its current state of art are needed. To the authors’ knowledge, a review of this topic has never been published in veterinary medicine; therefore, the aim of this study is to overview the treatments of chronic CHF secondary to MMVD in dogs from 1970 to 2020 using the general framework of narrative reviews.

Abstract

The treatment of chronic congestive heart failure (CHF), secondary to myxomatous mitral valve disease (MMVD) in dogs, has considerably changed in the last fifty years. An analysis of the literature concerning the therapy of chronic CHF in dogs affected by MMVD is not available, and it is needed. Narrative reviews (NRs) are aimed at identifying and summarizing what has been previously published, avoiding duplications, and seeking new study areas that have not yet been addressed. The most accessible open-access databases, PubMed, Embase, and Google Scholar, were chosen, and the searching time frame was set in five decades, from 1970 to 2020. The 384 selected studies were classified into categories depending on the aim of the study, the population target, the pathogenesis of MMVD (natural/induced), and the resulting CHF. Over the years, the types of studies have increased considerably in veterinary medicine. In particular, there have been 43 (24.29%) clinical trials, 41 (23.16%) randomized controlled trials, 10 (5.65%) cross-over trials, 40 (22.60%) reviews, 5 (2.82%) comparative studies, 17 (9.60%) case-control studies, 2 (1.13%) cohort studies, 2 (1.13%) experimental studies, 2 (1.13%) questionnaires, 6 (3.40%) case-reports, 7 (3.95%) retrospective studies, and 2 (1.13%) guidelines. The experimental studies on dogs with an induced form of the disease were less numerous (49–27.68%) than the studies on dogs affected by spontaneous MMVD (128–72.32%). The therapy of chronic CHF in dogs has considerably changed in the last fifty years: in the last century, some of the currently prescribed drugs did not exist yet, while others had different indications.

The mitochondrial signaling peptide MOTS-c improves myocardial performance during exercise training in rats

Cardiac remodeling is a physiological adaptation to aerobic exercise and which is characterized by increases in ventricular volume and the number of cardiomyocytes. The mitochondrial derived peptide MOTS-c functions as an important regulator in physical capacity and performance. Exercise elevates levels of endogenous MOTS-c in circulation and in myocardium, while MOTS-c can significantly enhance exercise capacity. However, the effects of aerobic exercise combined with MOTS-c on cardiac structure and function are unclear. We used pressure–volume conductance catheter technique to examine cardiac function in exercised rats with and without treatment with MOTS-c. Surprisingly, MOTS-c improved myocardial mechanical efficiency, enhanced cardiac systolic function, and had a tendency to improve the diastolic function. The findings suggest that using exercise supplements could be used to modulate the cardiovascular benefits of athletic training.

Levosimendan beyond inotropy and acute heart failure: Evidence of pleiotropic effects on the heart and other organs: An expert panel position paper

Levosimendan is a positive inotrope with vasodilating properties (inodilator) indicated for decompensated heart failure (HF) patients with low cardiac output. Accumulated evidence supports several pleiotropic effects of levosimendan beyond inotropy, the heart and decompensated HF. Those effects are not readily explained by cardiac function enhancement and seem to be related to additional properties of the drug such as anti-inflammatory, anti-oxidative and anti-apoptotic ones. Mechanistic and proof-of-concept studies are still required to clarify the underlying mechanisms involved, while properly designed clinical trials are warranted to translate preclinical or early-phase clinical data into more robust clinical evidence. The present position paper, derived by a panel of 35 experts in the field of cardiology, cardiac anesthesiology, intensive care medicine, cardiac physiology, and cardiovascular pharmacology from 22 European countries, compiles the existing evidence on the pleiotropic effects of levosimendan, identifies potential novel areas of clinical application and defines the corresponding gaps in evidence and the required research efforts to address those gaps.

Effectiveness of prophylactic levosimendan in high-risk valve surgery patients

Background

Levosimendan has anti-ischaemic effects, improves myocardial contractility and increases systemic, pulmonary and coronary vasodilatation. These properties suggest potential advantages in high-risk cardiac valve surgery patients where cardioprotection would be valuable. The present study investigated the peri-operative haemodynamic effects of prophylactic levosimendan infusion in cardiac valve surgery patients with low ejection fraction and/or severe pulmonary arterial hypertension.

Methods

Between May 2006 and July 2007, 20 consecutive patients with severe pulmonary arterial hypertension (systolic pulmonary artery pressure ≥ 60 mmHg) and/or low ejection fraction (< 50%) who underwent valve surgery in our clinic were included in the study and randomised into two groups. Levosimendan was administered to 10 patients in group I and not to the 10 patients in the control group. Cardiac output (CO), cardiac index (CI), systemic vascular resistance (SVR), pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (MPAP) were recorded for each patient preoperatively and for 24 hours following the operation.

Results

CO and CI values were higher in the levosimendan group during the study period (p < 0.05). MPAP and PVR values were significantly lower in the levosimendan group for the 24-hour period (p < 0.05) and SVR values were significantly lower after 24 hours in both groups. When clinical results were considered, no difference in favour of levosimendan was detected regarding the mortality and morbidity rates between the groups.

Conclusion

Levosimendan improved the haemodynamics in cardiac valve surgery patients with low ejection fraction and/or severe pulmonary arterial hypertension, and facilitated weaning from cardiopulmonary bypass in such high-risk patients when started as a prophylactic agent.

Levosimendan improves contractility in vivo and in vitro in a rodent model of post-myocardial infarction heart failure

AIM

As few studies have presented a thorough analysis of the effect of levosimendan (LEV) on contractility, our purpose was to investigate in vivo cardiac function as well as in vitro cardiomyocyte function and calcium (Ca(2+) ) handling following LEV treatment.

METHODS

Rats with post-myocardial infarction heart failure (HF) induced by ligation of the left anterior descending coronary artery and sham-operated animals were randomized to the infusion of LEV (2.4 μg kg(-1) min(-1) ) or vehicle for 40 min. Echocardiographic examination was coupled to pressure-volume sampling in the left ventricle before (B) and after (40 min) infusion. Isolated left ventricular cardiomyocytes were studied in an epifluorescence microscope.

RESULTS

HF LEV (n = 6), HF vehicle (n = 7), sham LEV (n = 5) and sham vehicle (n = 6) animals were included. LEV infusion compared to vehicle in HF animals reduced left ventricular end-diastolic pressure and mean arterial pressure (both P < 0.001) and improved the slope of the preload-recruitable stroke work (P < 0.05). Administrating LEV to HF cardiomyocytes in vitro improved fractional shortening and Ca(2+) sensitivity index ratio, and increased the diastolic Ca(2+) (all P < 0.01).

CONCLUSION

In HF animals, LEV improved the contractility by increasing the Ca(2+) sensitivity. Furthermore loading conditions were changed, and LEV could consequently change organ perfusion. An observed increase in diastolic Ca(2+) following LEV treatment and clinical implications of this should be further addressed.

β3-Adrenergic receptor antagonist improves exercise performance in pacing-induced heart failure

In heart failure (HF), the impaired left ventricular (LV) arterial coupling and diastolic dysfunction present at rest are exacerbated during exercise. We have previously shown that in HF at rest stimulation of β3-adrenergic receptors by endogenous catecholamine depresses LV contraction and relaxation. β3-Adrenergic receptors are activated at higher concentrations of catecholamine. Thus exercise may cause increased stimulation of cardiac β3-adrenergic receptors and contribute to this abnormal response. We assessed the effect of L-748,337 (50 μg/kg iv), a selective β3-adrenergic receptor antagonist (β3-ANT), on LV dynamics during exercise in 12 chronically instrumented dogs with pacing-induced HF. Compared with HF at rest, exercise increased LV end-systolic pressure (PES), minimum LV pressure (LVPmin), and the time constant of LV relaxation (τ) with an upward shift of early diastolic portion of LV pressure-volume loop. LV contractility decreased and arterial elastance (EA) increased. LV arterial coupling (EES/EA) (0.40 vs. 0.51) was impaired. Compared with exercise in HF preparation, exercise after β3-ANT caused similar increases in heart rate and PES but significantly decreased τ (34.9 vs. 38.3 ms) and LVPmin with a downward shift of the early diastolic portion of LV pressure-volume loop and further augmented dV/dtmax. Both EES and EES/EA (0.68 vs. 0.40) were increased. LV mechanical efficiency improved from 0.39 to 0.53. In conclusion, after HF, β3-ANT improves LV diastolic filling; increases LV contractility, LV arterial coupling, and mechanical efficiency; and improves exercise performance.

Pharmacology of levosimendan: inotropic, vasodilatory and cardioprotective effects

WHAT IS KNOWN AND OBJECTIVE

Positive inotropic agents are frequently used in acute decompensated heart failure (ADHF) due to left ventricular systolic dysfunction. These agents are known to improve cardiac performance and peripheral perfusion in the short-term treatment. However, several preclinical and clinical studies emphasized detrimental effects of these drugs on myocardial oxygen demand and on sympathetic tone entailing arrhythmogenesis. Levosimendan is an inotropic agent with an original mechanism of action. This review focuses on major data available for levosimendan.

METHODS

A literature search was conducted in the PubMed database by including studies published in English using combinations of the following key words, levosimendan, inotropic drugs and acute heart failure. Furthermore, bibliographies of selected references were also evaluated for relevant articles. The collection for this review was limited to the most recently available human and animal data.

RESULTS AND DISCUSSION

Levosimendan's vasodilatory and cardioprotective effects are mediated by calcium sensitization of contractile proteins and opening of adenosine triphosphate (ATP)-dependent K+ channels in vascular smooth muscle cells and on mitochondrial ATP-sensitive potassium [mito.K(ATP)] channels. This inotropic agent has mild PDE inhibitory action. Unlike other inotropic agents, levosimendan improves cardiac performance without activating the sympathetic nervous system. Moreover, there are evidences that levosimendan has additional anti-inflammatory and anti-apoptotic properties that prevent cardiac toxicity and contributes to positive hemodynamic response of the drug. Four randomized trials evaluated the effects of levosimendan on mortality in patients with acute decompensated chronic heart failure; nevertheless, a clear benefit has not been demonstrated so far. Although levosimendan is indicated for the treatment of ADHF (class of recommendation IIa, level of evidence B), it is has not been approved in all countries.

WHAT IS NEW AND CONCLUSION

This review summarizes the characteristics and the current knowledge of the literature on levosimendan and its active metabolite OR-1896.

Heart Transplantation in a 14-Year-Old Boy in the Presence of Severe Out-of-Proportion Pulmonary Hypertension due to Restrictive Left Heart Disease: A Case Report

A 14-year-old boy after balloon valvuloplasty of severe aortic valve stenosis in the neonatal period was referred for heart-lung transplantation because of high grade pulmonary hypertension and left heart dysfunction due to endocardial fibroelastosis with severe mitral insufficiency. After heart catheterization, hemodynamic parameters were invasively monitored: a course of levosimendan and initiation of diuretics led to a decrease of pulmonary capillary wedge pressure (from maximum 35 to 24 mmHg). Instead of an expected decrease, mean pulmonary artery pressures (mPAP) increased up to 80 mmHg with increasing transpulmonary pressure gradient (TPG) up to 55 mmHg. Oral bosentan and intravenous epoprostenol then led to a ~50% decrease of mPAP (TPG between 16 and 22 mmHg). The boy was listed solely for heart transplantation which was successfully accomplished 1 month later.

Inotropes for the management of acute heart failure patients with renal dysfunction. Still an option?

INTRODUCTION

Renal dysfunction is highly prevalent in patients with acute heart failure (AHF). These patients are more vulnerable in worsening of kidney function and have also higher mortality rates.

AREAS COVERED

Recent developments in the understanding of bidirectional interaction between heart and kidney are reviewed in the context of the potential impact of inotropes on renal function. Key clinical trials reporting the use of inotropes in AHF patients with renal dysfunction are discussed in this review.

EXPERT OPINION

Inotropes may be indicated on a short-term basis and under close monitoring in AHF with renal dysfunction mostly in cases of low output heart failure that can provoke renal hypoperfusion. Dopamine administration with low dose of i.v. furosemide has been recently compared with high dose of i.v. furosemide alone, demonstrating lower rates of worsening renal function and electrolyte disturbances. Moreover, small clinical trials have shown that the novel inodilator levosimendan seems to be superior to dobutamine or placebo in improving renal function in patients with acutely decompensated heart failure. The impact of novel inotropes on kidney function is still unclear. Randomized clinical trials are required in order to identify the role of inotropes in the management and/or prevention of acute cardiorenal syndrome.

Levosimendan restores the positive force-frequency relation in heart failure

Frequency potentiation of contractile function is a major mechanism of the increase in myocardial performance during exercise. In heart failure (HF), this positive force-frequency relation is impaired, and the abnormal left ventricular (LV)-arterial coupling is exacerbated by tachycardia. A myofilament Ca(2+) sensitizer, levosimendan, has been shown to improve exercise tolerance in HF. This may be due to its beneficial actions on the force-frequency relation and LV-arterial coupling (end-systolic elastance/arterial elastance, E(ES)/E(A)). We assessed the effects of therapeutic doses of levosimendan on the force-frequency relation and E(ES)/E(A) in nine conscious dogs after pacing-induced HF using pressure-volume analysis. Before HF, pacing tachycardia increased E(ES), shortened τ, and did not impair E(ES)/E(A) and mechanical efficiency (stroke work/pressure-volume area, SW/PVA). In contrast, after HF, pacing at 140, 160, 180, and 200 beat/min (bpm) produced smaller a increase of E(ES) or less shortening of τ, whereas E(ES)/E(A) (from 0.56 at baseline to 0.42 at 200 bpm) and SW/PVA (from 0.52 at baseline to 0.43 at 200 bpm) progressively decreased. With levosimendan, basal E(ES) increased 27% (6.2 mmHg/ml), τ decreased 11% (40.8 ms), E(ES)/E(A) increased 34% (0.75), and SW/PVA improved by 15% (0.60). During tachycardia, E(ES) further increased by 23%, 37%, 68%, and 89%; τ decreased by 9%, 12%, 15%, and 17%; and E(ES)/E(A) was augmented by 11%, 16%, 31%, and 33%, incrementally, with pacing rate. SW/PVA was improved (0.61 to 0.64). In conclusion, in HF, treatment with levosimendan restores the normal positive LV systolic and diastolic force-frequency relation and prevents tachycardia-induced adverse effect on LV-arterial coupling and mechanical efficiency.

[Left ventricular diastolic dysfunction. Implications for anesthesia and critical care]

Over the last two decades there has been a growing recognition that cardiac function is not solely determined by systolic but also essentially by diastolic function. Left ventricular diastolic dysfunction is characterized by an impairment of ventricular filling caused either by abnormal relaxation, an active energy consuming process or decreased compliance, which is determined by passive tissue properties of the ventricle. Doppler echocardiography, including tissue Doppler imaging, has emerged as the preferred clinical tool for the assessment of left ventricular diastolic function. Recently the importance of left ventricular diastolic function is increasingly being recognized also during the perioperative period. Newer studies have shown that after cardiopulmonary bypass there is a significant decrease in left ventricular compliance. Experimental studies have demonstrated that sepsis is associated with a decrease in both active relaxation and ventricular compliance. Initial studies are also focusing on therapeutic options for patients with isolated diastolic dysfunction.

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.

[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.

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.

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.

Levosimendan restores both systolic and diastolic cardiac performance in lipopolysaccharide-treated rabbits: Comparison with dobutamine and milrinone

OBJECTIVE

Current treatment strategies for severe septic conditions (i.e., intravenous fluids, vasopressors, and cardiac inotropes) reestablish fluid balance and improve cardiac systole but do not address diastolic dysfunction. Our study aimed to fully characterize both systolic and diastolic abnormalities of sepsis-associated heart failure and to identify treatment that would support full-cycle cardiac improvement.

DESIGN

Endotoxin-injected rabbits, an animal model of abnormal cardiac function in human sepsis, were used to delineate cardiac abnormalities and to examine effects of drug treatments on heart systolic and diastolic function (n = 30); saline-injected animals served as comparators (n = 17). As treatment, three inotropes commonly used for treatment of cardiac failure were infused for 45 mins in separate animal groups-milrinone, dobutamine, and levosimendan.

MEASUREMENTS

Variables of left ventricular systolic and diastolic function were assessed with a pressure conductance catheter. Measurements were made before and after endotoxin/saline injection and before and after inotrope treatment.

RESULTS

Pressure-volume analyses of the left ventricle showed marked impairment in systolic function and in all indices of diastolic function (isovolumic relaxation time constant, left ventricular end-diastolic pressure, and end-diastolic pressure-volume relationship) in endotoxin-treated rabbits. The inotropes, milrinone, dobutamine, and levosimendan, could each partially or completely restore systolic function in the lipopolysaccharide-treated rabbits. However, only levosimendan therapy led to additional beneficial effects on left ventricular relaxation and diastolic function.

CONCLUSIONS

Cardiac failure in severe sepsis results from impairments in both systolic and diastolic functions. Treatment with the calcium sensitizer levosimendan improved both systolic and diastolic cardiac functions in septic animals, but cyclic adenosine monophosphate-dependent inotropes milrinone and dobutamine only improved systolic function.

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.

Direct myocardial effects of levosimendan in humans with left ventricular dysfunction: alteration of force-frequency and relaxation-frequency relationships

BACKGROUND

Enthusiasm for the development of Ca2+ sensitizers as inotropic agents for heart failure has been tempered by reports of impaired relaxation. Levosimendan, which increases myofilament Ca2+ sensitivity via Ca2+-dependent binding to troponin C, exerts positive inotropic and lusitropic effects in failing human myocardium in vitro. We sought to determine the direct effects of levosimendan on failing human myocardium in vivo, and in particular whether levosimendan exerts heart rate-dependent effects on systolic or diastolic function.

METHODS AND RESULTS

Ten patients with left ventricular dysfunction caused by nonischemic dilated cardiomyopathy (mean left ventricular ejection fraction, 27+/-2%) were instrumented with an infusion catheter in the left main coronary artery, a high-fidelity micromanometer-tipped catheter in the left ventricle, and a bipolar pacing wire in the right atrium. Inotropic (peak +dP/dt) and lusitropic (Tau) responses were assessed during continuous intracoronary drug infusion in sinus rhythm followed by atrial pacing at 20, 40, and 60 beats per minute above the sinus rate. Under control conditions (intracoronary 5% dextrose in water), atrial-pacing tachycardia decreased Tau by 13% (P<0.05), but did not increase +dP/dt. Intracoronary levosimendan (3.75 and 12.5 microg/min for 15 minutes each) increased +dP/dt dose-dependently and decreased Tau over a range of heart rates, but did not alter the slope of the force-frequency or relaxation-frequency relationship.

CONCLUSIONS

Myocardial calcium sensitization with levosimendan exerts mild inotropic and lusitropic effects in humans with left ventricular dysfunction, but does not alter the force-frequency or relaxation-frequency relationship.

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.

Mechanisms of a reduced cardiac output and the effects of milrinone and levosimendan in a model of infant cardiopulmonary bypass

OBJECTIVES

A low cardiac output state is an important cause of morbidity after pediatric cardiopulmonary bypass. The objectives of our study were to define the early precipitants of the reduced cardiac output and to investigate the effects on these of milrinone and levosimendan in a model of pediatric cardiopulmonary bypass.

DESIGN

Experimental study.

SETTING

: Research laboratory at a university-affiliated, tertiary pediatric center.

SUBJECTS

Eighteen piglets.

INTERVENTIONS

Piglets, instrumented with systemic, pulmonary arterial, and coronary sinus catheters, pulmonary and circumflex arterial flow probes, and a left ventricular conductance-micromanometer-tipped catheter, underwent cardiopulmonary bypass with aortic cross-clamp and cardioplegic arrest. At 120 mins, they were assigned to control, milrinone, or levosimendan groups and studied for a further 120 mins.

MEASUREMENTS AND MAIN RESULTS

In controls, between 120 and 240 mins, cardiac output decreased by 15%. Systemic vascular resistance was unchanged, but pulmonary vascular resistance increased by 19%. Systemic arterial elastance increased by 17%, indicating increased afterload. End-systolic elastance was unchanged, and coronary sinus oxygen tension decreased by 4.0 +/- 1.7 mm Hg. In animals receiving milrinone cardiac output was preserved, and in animals receiving levosimendan cardiac output increased by 14%. Both drugs prevented an increase in arterial elastance and pulmonary vascular resistance after cardiopulmonary bypass. Systemic vascular resistance decreased by 31% after levosimendan, and end-systolic elastance increased by 48%, indicating improved contractility. Both agents prevented a decrease in coronary sinus oxygen tension.

CONCLUSIONS

Increased afterload, which is not matched by an equivalent elevation in contractility, contributes to the reduced cardiac output early after pediatric cardiopulmonary bypass in this model. This increase is prevented by milrinone and levosimendan. Both agents exert additional beneficial effects on pulmonary vascular resistance and myocardial oxygen balance, although levosimendan has greater inotropic properties.

Effects of levosimendan on right ventricular function in patients with advanced heart failure

Right ventricular (RV) dysfunction frequently complicates advanced left ventricular heart failure and contributes to an unfavorable prognosis. Levosimendan is a novel inodilator that beneficially affects hemodynamics and left ventricular systolic and diastolic function in patients with advanced heart failure. However, its effects on RV function have not yet been properly assessed in these patients. In this randomized trial, the impact of levosimendan or placebo on various echocardiographic parameters of RV systolic and diastolic function was investigated in 54 patients with advanced heart failure due to left ventricular systolic dysfunction. Tissue Doppler imaging maximal systolic tricuspid annular velocity (S wave) increased significantly only in the levosimendan group (8.2 +/- 3.2 vs 9.0 +/- 3.0 cm/s, p <0.03). Tissue Doppler imaging RV early diastolic velocity (E wave) and the ratio of early to late diastolic velocities (E/A) also increased significantly after levosimendan administration (p <0.01 and p <0.05, respectively). Systolic pulmonary arterial pressure decreased significantly (54 +/- 11 vs 43 +/- 11 mm Hg, p <0.01) in the levosimendan-treated patients. Levosimendan beneficially modulated neurohormonal and inflammatory status by decreasing B-type natriuretic peptide levels (p <0.05) and by altering the ratio of interleukin-6 to interleukin-10 in favor of the latter (p <0.05). In conclusion, levosimendan could offer further therapeutic advantages in patients with advanced heart failure by improving systolic and diastolic RV function.

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.

Hemodynamic Effects of Long-Term Cardiac Resynchronization Therapy

Background— Acute hemodynamic effects of cardiac resynchronization therapy (CRT) were reported previously, but detailed invasive studies showing hemodynamic consequences of long-term CRT are not available.

Methods and Results— We studied 22 patients scheduled for implantation of a CRT device based on conventional criteria (New York Heart Association class III or IV, left ventricular [LV] ejection fraction <35%, left bundle-branch block, and QRS duration >120 ms). During diagnostic catheterization before CRT, we acquired pressure-volume loops using conductance catheters during atrial pacing at 80, 100, 120, and 140 bpm. Studies were repeated during biventricular pacing at the same heart rates after 6 months of CRT. Our data show a significant clinical benefit of CRT (New York Heart Association class change from 3.1±0.5 to 2.1±0.8; quality-of-life score change from 44±12 to 31±16; and 6-minute hall-walk distance increased from 260±149 to 396±129 m; all P <0.001), improved LV ejection fraction (from 29±10% to 40±13%, P <0.01), decreased end-diastolic pressure (from 18±8 to 13±6 mm Hg, P <0.05), and reverse remodeling (end-diastolic volume decreased from 257±67 to 205±54 mL, P <0.01). Previously reported acute improvements in LV function remained present at 6 months: dP/dt max increased 18%, −dP/dt min increased 13%, and stroke work increased 34% (all P <0.01). Effects of increased heart rate were improved toward more physiological responses for LV ejection fraction, cardiac output, and dP/dt max . Moreover, our study showed improved ventricular-arterial coupling (69% increase, P <0.01) and improved mechanical efficiency (44% increase, P <0.01).

Conclusions— Hemodynamic improvements with CRT, previously shown in acute invasive studies, are maintained chronically. In addition, ventricular-arterial coupling, mechanical efficiency, and chronotropic responses are improved after 6 months of CRT. These findings may help to explain the improved functional status and exercise tolerance in patients treated with CRT.

Levosimendan protects against experimental endotoxemic acute renal failure

Endotoxemia induces a hemodynamic form of acute renal failure (ARF; renal vasoconstriction +/- reduced glomerular ultrafiltration coefficient, K(f); minimal/no histological damage). We tested whether levosimendan (LS), an ATP-sensitive K+ (K(ATP)) channel opener with cardiac ionotropic and possible anti-inflammatory properties, might have utility in combating this form of ARF. CD-1 mice were injected with LPS +/- LS. LS effects on LPS-induced systemic inflammation (plasma TNF-alpha/MCP-1; cardiorenal mRNAs), plasma NO levels, and azotemia were assessed. Because K(ATP) channel opening has been reported to mediate hypoxic tubular injury, possible adverse LS effects on ischemic ARF and ATP depletion injury were sought. Effects of diazoxide (another K(ATP) channel agonist) and glibenclamide (a channel antagonist) on hypoxic tubular injury also were assessed. Finally, the ability of LS to alter rat mesangial cell (MC) contraction in response to ANG II (elevated in sepsis) was tested. LS conferred almost complete protection against LPS-induced ARF, without any apparent reduction in the LPS-induced inflammatory response. Neither LS nor diazoxide altered ATP depletion-mediated tubule injury (in vivo or in vitro). Conversely, glibenclamide induced a marked and direct cytotoxic effect. LS completely blocked ANG II-induced MC contraction, an action likely to increase K(f). We concluded that 1) LS can confer marked protection against LPS-induced ARF; 2) this likely stems from vasoactive properties, rather than reductions in LPS-induced inflammation; and 3) K(ATP) channel agonists (but not antagonists) appear to be devoid of toxic proximal tubular cell effects. This suggests that LS, and other K(ATP) channel agonists, have a margin of safety if employed in situations (sepsis syndrome, heart failure) in which severe renal vasoconstriction might lead to ischemic ARF.

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.

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.

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.

Effects of levosimendan on markers of left ventricular diastolic function and neurohormonal activation in patients with advanced heart failure

In this randomized, placebo-controlled study, it was found that a 24-hour levosimendan infusion improves echocardiographic markers of abnormal left ventricular diastolic function (transmitral flow patterns and mitral annulus velocities, as assessed by transthoracic pulse-wave Doppler and tissue Doppler imaging, respectively) and reduces substances of excessive neurohormonal activation (plasma B-type natriuretic peptide and interleukin-6) in patients with advanced heart failure. Moreover, levosimendan-treated patients had fewer events and longer progression-free survival during a 5-month follow-up compared with those who received placebo. Thus, levosimendan seems to be effective in improving left ventricular diastolic function and reducing neurohormonal activation in patients with severe heart failure.

An emerging role for calcium sensitisation in the treatment of heart failure

Heart failure occurs in 2 - 3% of the adult population in the developed world. With decompensation of cardiac function, haemodynamic stability can be achieved by using intravenous vasodilators, diuretics and inotropes. Unlike traditional inotropes, Ca2+ sensitisers enhance cardiac function without significantly increasing cardiac oxygen consumption, promoting arrhythmia or impairing lusitropy. The most promising drug in this new class is levosimendan, which has a unique dual mechanism; it enhances cardiac output through a Ca(2+)-dependent stabilisation of cardiac myofilaments and exhibits vasodilatory effects by opening ATP-dependent K(+) channels. Clinical trials have demonstrated the beneficial haemodynamic effects of levosimendan, and prospective trials are currently underway to confirm its potential benefits on long-term prognosis. Updated guidelines from the European Society of Cardiology advise on how to incorporate levosimendan into care for patients who have acute heart failure.

Protein kinase C epsilon induces systolic cardiac failure marked by exhausted inotropic reserve and intact Frank-Starling mechanism

Myofilament dysfunction is a common point of convergence for many forms of heart failure. Recently, we showed that cardiac overexpression of PKC epsilon initially depresses myofilament activity and then leads to a progression of changes characteristic of human heart failure. Here, we examined the effects of PKC epsilon on contractile reserve, Starling mechanism, and myofilament activation in this model of end-stage dilated cardiomyopathy. Pressure-volume loop analysis and echocardiography showed that the PKC epsilon mice have markedly compromised systolic function and increased end-diastolic volumes. Dobutamine challenge resulted in a small increase in contractility in PKC epsilon mice but failed to enhance cardiac output. The PKC epsilon mice showed a normal length-dependent tension development in skinned cardiac muscle preparations, although Frank-Starling mechanism appeared to be compromised in the intact animal. Simultaneous measurement of tension and ATPase demonstrated that the maximum tension and ATPase were markedly lower in the PKC epsilon mice at any length or Ca2+ concentration. However, the tension cost was also lower indicating less energy expenditure. We conclude 1) that prolonged overexpression of PKC epsilon ultimately leads to a dilated cardiomyopathy marked by exhausted contractile reserve, 2) that PKC epsilon does not compromise the Frank-Starling mechanism at the myofilament level, and 3) that the Starling curve excursion is limited by the inotropic state of the heart. These results reflect the significance of the primary myofilament contractilopathy induced by phosphorylation and imply a role for PKC epsilon-mediated phosphorylation in myofilament physiology and the pathophysiology of decompensated cardiac failure.