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

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

BACKGROUND

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Levosimendan Does Not Improve Cardiac Output or Blood Pressure in a Rodent Model of Propranolol Toxicity When Administered Using Various Dosing Regimens

Background: Levosimendan (CAS: 141505-33-1) is a myocardial calcium sensitizer that improves myocardial contractility in various forms of heart failure. It produces a moderate improvement in cardiac output (CO) without an improvement in blood pressure (BP) in verapamil and metoprolol poisoned rodents. Aim: To assess the effect of various levosimendan dosing regimens on hemodynamics in a rodent model of propranolol poisoning. Method: Male Wistar rats (350-450 g) were anesthetized, ventilated, and instrumented to record BP, heart rate (HR), and CO. Propranolol was infused continually. When BP dropped to 50% of baseline rats received 1 of 7 treatments: (1) 0.9% saline (control), (2) levosimendan 36 μg/kg loading dose then 0.6 μg/kg per min, (3) levosimendan 0.6 μg/kg per min, (4) epinephrine 0.5 μg/kg per min, (5) levosimendan 70 μg/kg loading dose then 1.2 μg/kg per min, (6) levosimendan 1.2 μg/kg per min, and (7) levosimendan 70 μg/kg loading dose alone. Hemodynamics were recorded every 10 minutes for 70 minutes. Cardiac output, mean arterial pressure, and HR for each group were compared with control. Results: All groups had comparable baseline and maximal toxicity hemodynamics prior to initiation of treatment. Levosimendan did not improve CO or BP with any dosing regimen. Blood pressure tended to be lower than control for all doses of levosimendan. Epinephrine significantly improved BP but not CO compared to all other treatment groups. Survival did not differ between groups. Conclusions: Unlike in verapamil and metoprolol poisoning models, levosimendan did not improve CO or survival in propranolol poisoning. Epinephrine improved BP, but not CO, suggesting that its actions were due to peripheral vasoconstriction.

Levosimendan infusion improves cardiac output but not blood pressure in a rodent model of severe metoprolol toxicity

Levosimendan (Levo) is an inodilator improving cardiac output (CO) and reducing afterload in heart failure. Previously, we reported that Levo improved CO but not blood pressure (BP) in a rodent model of verapamil poisoning. We theorised that Levo-induced vasodilation should not influence BP to a similar degree in metoprolol poisoning. Aim: To assess the effect of Levo on haemodynamics in a rodent model of metoprolol poisoning. Method: Anaesthetized male Wistar rats were infused metoprolol continuously. When the BP dropped to 50% of baseline (time 0) rats received 1 of the 4 treatments: (a) control (0.9% saline bolus + infusion); (b) Levo-l (Levo 36 μm/kg loading dose followed by 0.6 μm/kg/min); (c) Levo-I (Levo infusion only at 0.6 μm/kg/min); and (d) Epi (epinephrine 0.5 μm/kg/min). All groups received comparable fluid volumes. Haemodynamics were recorded every 10 min for 70 min. CO, mean arterial pressure (MAP) and heart rate (HR) of each group were compared to the control. Results: All groups had comparable baseline and time 0 HR, MAP and CO. Levo-L and Levo-I rats showed significantly greater CO at t = 10 min ( p > 0.02 and p > 0.04, respectively). CO was higher at all other time points for both Levo groups. This was not statistically significant. Levo did not improve MAP compared to control. Adrenaline increased MAP but not CO compared to control and Levo groups. Conclusion: Levo did not improve MAP but moderately improved CO compared to control in this model of metoprolol poisoning. The response was similar to that reported previously in verapamil-poisoned rats. The improvement in MAP seen with epinephrine was most likely vasoconstriction mediated.

Clinical development of pharmacologic agents for acute heart failure syndromes: a proposal for a mechanistic translational phase

Hospitalization for acute heart failure syndromes (AHFS) predicts a poor prognosis, with postdischarge mortality and rehospitalization rates reaching 45% within 60 to 90 days. Despite the use of evidence-based therapies and adherence to national process measures, these event rates have largely remained the same over the past decade. Given the current and growing burden of AHFS, there exists a substantial unmet need for novel therapies that improve outcomes. However, attempts to improve symptoms and/or reduce postdischarge events have failed to produce positive results, either because of safety and/or efficacy. These negative results may be related to the drug itself, the protocol in terms of patient selection and/or end points, and/or the trial execution. Although experts may not agree on the exact reasons to explain the lack of success to date of phase III trials in AHFS, there is agreement that clinical benefits observed in phase II trials were not reproduced in phase III trials. A different approach may be needed. In November of 2009, a meeting was held at the Food and Drug Administration with the primary purpose of identifying the reasons why benefits observed during phase II did not translate into benefits in phase III to improve future trial design. Although multiple domains of trial design were discussed, the participants identified a lack of in-depth understanding of novel molecules before pivotal trials in AHFS as a possible contributor to the disappointing results of recent large trials. In this brief report, we outline the T1 or translational phase of research for AHFS clinical development as an important first step toward greater success in AHFS clinical trials.

Oxygen-Wasting Effect of Inotropy

Background— We addressed the hypothesis that the inotropic drugs dobutamine and levosimendan both induce surplus oxygen consumption (oxygen wasting) relative to their contractile effect in equipotent therapeutic doses, with levosimendan being energetically more efficient.

Methods and Results— Postischemically reduced left ventricular function (stunning) was created by repetitive left coronary occlusions in 22 pigs. This contractile dysfunction was reversed by infusion of either levosimendan (24 μg/kg loading and 0.04 μg · kg −1 · min −1 infusion) or an equipotent dose of dobutamine (1.25 μg · kg −1 · min −1 ). Contractility and cardiac output were normalized by both drug regimens. The energy cost of drug-induced contractility enhancement was assessed by myocardial oxygen consumption related to the mechanical indexes tension-time index, pressure-volume area, and total mechanical energy. ANCOVA did not reveal any increased oxygen cost of contractility for either drug in these doses. However, both dobutamine and levosimendan at supratherapeutic levels (10 μg · kg −1 · min −1 and 48 μg/kg loading with 0.2 μg · kg −1 · min −1 infusion, respectively) induced a highly significant increase in oxygen consumption related to mechanical work, compatible with the established oxygen-wasting effect of inotropy ( P <0.001 for all mechanical indexes with dobutamine; P =0.007 for levosimendan as assessed by pressure-volume area).

Conclusion— Therapeutic levels of neither dobutamine nor levosimendan showed inotropic oxygen wasting in this in vivo pig model. Thus, relevant hemodynamic responses can be achieved with an adrenergic inotrope without surplus oxygen consumption.

Ryanodine receptor-mediated arrhythmias and sudden cardiac death

The cardiac ryanodine receptor-Ca²⁺ release channel (RyR2) is an essential sarcoplasmic reticulum (SR) transmembrane protein that plays a central role in excitation–contraction coupling (ECC) in cardiomyocytes. Aberrant spontaneous, diastolic Ca²⁺ leak from the SR due to dysfunctional RyR2 contributes to the formation of delayed after-depolarisations, which are thought to underlie the fatal arrhythmia that occurs in both heart failure (HF) and in catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT is an inherited disorder associated with mutations in either the RyR2 or a SR luminal protein, calsequestrin. RyR2 shows normal function at rest in CPVT but the RyR2 dysfunction is unmasked by physical exercise or emotional stress, suggesting abnormal RyR2 activation as an underlying mechanism. Several potential mechanisms have been advanced to explain the dysfunctional RyR2 observed in HF and CPVT, including enhanced RyR2 phosphorylation status, altered RyR2 regulation at luminal/cytoplasmic sites and perturbed RyR2 intra/inter-molecular interactions. This review considers RyR2 dysfunction in the context of the structural and functional modulation of the channel, and potential therapeutic strategies to stabilise RyR2 function in cardiac pathology.

New therapies in acute decompensated heart failure

PURPOSE OF REVIEW

Hospitalization and mortality rates associated with heart failure are persistently high. This is due partly to aging of the population but mostly to delayed progress in the pharmacological treatment of decompensated heart failure. We will review the current recommendations and most recent advancement in the pharmacological treatment of acute decompensated heart failure while providing a systematic approach to the management of this prevalent condition.

RECENT FINDINGS

Loop diuretics, nitrates and inotropes such as dobutamine and milrinone are the current mainstay of acute heart failure management although their associated morbidity and possible mortality have raised serious concerns. Recent vasoactive agents such as Nesiritide, Tolvaptan and more recently the inotropic agent Levosimedan could offer improved hemodynamics and congestive relief to patients in acute pulmonary edema.

SUMMARY

Despite the promising results of these agents, further clinical trials are required prior to their international approval as first-line therapy. Although we can be optimistic that these vasoactive drugs might have favorable clinical outcomes and improve the intricate management of decompensated heart failure, their associated mortality benefit remains unclear and controversial.

Drug discovery for heart failure: a new era or the end of the pipeline?

Although there have been significant advances in the therapy of heart failure in recent decades, such as the introduction of beta-blockers and antagonists of the renin-angiotensin system, there is still a major unmet need for better therapies for many patients with heart failure. However, disappointment related to late-stage clinical failures of a number of novel agents, including endothelin antagonists and tumour-necrosis factor blockers, has reduced the impetus of drug development in this field. Here, we review possible targets for heart failure therapy that have emerged from recent progress in our understanding of the underlying disease mechanisms, and highlight key issues that need to be addressed to improve the chances of success of novel therapies directed against these targets.