Levosimendan: mechanistic insight and its diverse future aspects in cardiac care

Inotropic agents are generally recommended to use in patients with acute decompensated heart failure (HF) with reduced ejection fraction (HFrEF) concurrent to end-organ dysfunction. However, due to certain pharmacological limitations like developing life threatening arrhythmia and tolerance, cannot be employed as much as needed. Meanwhile, Calcium ion (Ca²⁺) sensitisers exhibits their inotropic action by increasing the sensitivity of the cardiomyocyte to intracellular Ca²⁺ ion and have been reported as emerging therapeutic alternative in HF cases. Levosimendan (LEVO) is an inodilator and with its unique pharmacology justifying its use in a wide range of cardiac alterations in HF particularly in undergoing cardiac surgery. It is also reported to be better than classical inotropes in maintaining cardiac mechanical efficacy and reducing congestion in acute HF with hypotension. This review paper was designed to compile various evidence about basic pharmacology and potential clinical aspects of LEVO in cardiac surgery and other HF associated alterations. This will benefit directly to the researcher in initiating research and to fill the gaps in the area of thrust.

Hemodynamic effects of inotropic drugs in heart failure: A network meta-analysis of clinical trials

BACKGROUND

There is currently no consensus on the appropriate selection of inotropic therapy in ventricular dysfunction. The objective of the study was to detect the effects of different inotropes on the hemodynamics of patients who developed low cardiac output.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched (all updated December 31, 2017). The inclusion criteria were as follows: low cardiac index (CI < 2.5 L/min/m) or New York Heart Association class II-IV, and at least 1 group receiving an inotropic drug compared to another group receiving a different inotropic/placebo treatment. The exclusion criteria were studies published as an abstract only, crossover studies, and studies with a lack of data on the cardiac index.

RESULTS

A total of 1402 patients from 37 trials were included in the study. Inotropic drugs were shown to increase the cardiac index (0.32, 95%CI:0.25, 0.38), heart rate (7.68, 95%CI:6.36, 9.01), and mean arterial pressure (3.17, 95%CI:1.96, 4.38) than the placebo. Overall, the pooled estimates showed no difference in terms of cardiac index, heart rate, mean arterial pressure, systemic vascular resistance, and mean pulmonary arterial pressure among the groups receiving different inotropes.

CONCLUSIONS

Our systematic review found that inotrope therapy is not associated with the amelioration of hemodynamics. An accurate evaluation of the benefits and risks, and selection of the correct inotropic agent is required in all clinical settings.

Expanded criteria for retinopathy of prematurity screening in moderately preterm infants: Single-center pilot study

BACKGROUND

While developed countries seek to lower the gestational age and birthweight parameters in retinopathy of prematurity (ROP) screening, older, larger infants still develop ROP in other parts of the world. The aim of this study was therefore to define criteria to identify potential ROP developers who are outliers of the common screening range.

METHODS

A retrospective medical record review was performed in 147 inborn moderately preterm infants admitted to the neonatal intensive care unit during the study period. Univariate and logistic regression analysis was carried out.

RESULTS

Forty-two infants developed ROP. Gestational age (31.4 ± 1.1 vs 32.4 ± 1.0 weeks, P = 0.000) and birthweight (1607.7 ± 339.4 vs 1846.4 ± 317.2 g, P = 0.000) were lower in those who developed ROP. Respiratory distress syndrome (P = 0.026) and documented sepsis (P = 0.003) were significant comorbidities on univariate analysis. Inotrope need >72 h starting in the first week of life (P = 0.004; OR, 5.181) and more than three transfusions of packed red blood cells (P = 0.028; OR, 3.891) were also significant, both on univariate and multivariate analysis.

CONCLUSIONS

In moderately preterm infants, status should be evaluated in order to effectively select candidates for ROP screening without missing potential ROP developers.

Myosin Activator Omecamtiv Mecarbil Increases Myocardial Oxygen Consumption and Impairs Cardiac Efficiency Mediated by Resting Myosin ATPase Activity

BACKGROUND

Omecamtiv mecarbil (OM) is a novel inotropic agent that prolongs systolic ejection time and increases ejection fraction through myosin ATPase activation. We hypothesized that a potentially favorable energetic effect of unloading the left ventricle, and thus reduction of wall stress, could be counteracted by the prolonged contraction time and ATP-consumption.

METHODS AND RESULTS

Postischemic left ventricular dysfunction was created by repetitive left coronary occlusions in 7 pigs (7 healthy pigs also included). In both groups, systolic ejection time and ejection fraction increased after OM (0.75 mg/kg loading for 10 minutes, followed by 0.5 mg/kg/min continuous infusion). Cardiac efficiency was assessed by relating myocardial oxygen consumption to the cardiac work indices, stroke work, and pressure-volume area. To circumvent potential neurohumoral reflexes, cardiac efficiency was additionally assessed in ex vivo mouse hearts and isolated myocardial mitochondria. OM impaired cardiac efficiency; there was a 31% and 23% increase in unloaded myocardial oxygen consumption in healthy and postischemic pigs, respectively. Also, the oxygen cost of the contractile function was increased by 63% and 46% in healthy and postischemic pigs, respectively. The increased unloaded myocardial oxygen consumption was confirmed in OM-treated mouse hearts and explained by an increased basal metabolic rate. Adding the myosin ATPase inhibitor, 2,3-butanedione monoxide abolished all surplus myocardial oxygen consumption in the OM-treated hearts.

CONCLUSIONS

Omecamtiv mecarbil, in a clinically relevant model, led to a significant myocardial oxygen wastage related to both the contractile and noncontractile function. This was mediated by that OM induces a continuous activation in resting myosin ATPase.

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.

Effect of pimobendan in addition to standard therapy for heart failure on prevention of readmission in elderly patients with severe chronic heart failure

AIM

We evaluated the effect of pimobendan, a positive inotropic agent, in elderly patients with frequent readmission as a result of heart failure despite conventional therapy.

METHODS

Pimobendan was given to five male patients with severe chronic heart failure (New York Heart Association class III-IV) (age range 69-89 years; mean 78 ± 8 years; ischemic cardiomyopathy in three cases, dilated cardiomyopathy in two cases) who required repeated admission for heart failure despite conventional therapy with angiotensin inhibitors, beta-blockers, diuretics and anti-arrhythmic agents. After the addition of pimobendan at a dose of 1.25-3.75 mg/day, we evaluated serum levels of brain natriuretic peptide (BNP), left ventricular ejection fraction (LVEF), septal e' and left ventricular end-diastolic diameter (LVDD) by echocardiography, as well as readmission rates for more than 2 years.

RESULTS

The serum level of BNP significantly decreased after treatment with pimobendan, although its level returned to pretreatment levels after 2 years. LVEF significantly improved after the treatment, with the improvement continuing beyond the 2 years, although LVDD did not change after treatment. Septal e' significantly improved after the treatment, although its level returned to pretreatment levels at 2 years after the treatment. Readmission rates significantly decreased for 2 years after the treatment, although one patient required cardiac resynchronization therapy for severe heart failure, and another patient required cardiac pacemaker implantation for sick sinus syndrome 2 years after adding pimobendan.

CONCLUSIONS

Pimobendan in conjunction with conventional therapy for heart failure decreases the readmission rate in elderly patients with severe heart failure for at least 2 years.

Novel use of a short-acting intravenous beta blocker in combination with inotropic therapy as a bridge to chronic oral beta blockade in patients with advanced heart failure

The role for beta blockers in advanced heart failure (New York Heart Association class IV) remains undefined because of concerns about tolerability and uncertainty about efficacy. We report the use of a short-acting intravenous beta blocker in combination with inotropic therapy as a means to bridge five patients with advanced heart failure to chronic oral beta blockade; two of these patients had been chronically managed with intravenous inotrope. At 4 months' follow-up, all patients remained on beta-blocker therapy and none was hospitalized for heart failure or had received intravenous diuretics. Given the early separation of survival curves in the randomized clinical trials of beta blockers in heart failure, it is possible that these patients will accrue a survival benefit. We conclude that some patients with advanced heart failure can be offered oral beta-blocker therapy by bridging with a combination of intravenous inotrope and short-acting intravenous beta blocker.

The new compound, LASSBio 294, increases the contractility of intact and saponin-skinned cardiac muscle from Wistar rats

1. A new compound designated as LASSBio 294 (L-294), 3,4-methylenedioxybenzoyl-2-thienylhydrazone, was synthesized as an alternative therapeutic for cardiac dysfunction. 2. L-294 increased in a dose-dependent manner the spontaneous contractions of isolated hearts from Wistar rats with maximal effect (128.0+/-0.7% of control) observed at 25 microM. 3. The positive inotropic effect of L-294 was also observed in electrically stimulated cardiac tissues from Wistar rats. The maximal increment of twitches, at 200 microM, was 163.1+/-18.4% for atrial, 153.5+/-28.5% for papillary and 201.5+/-18.5% for ventricular muscles. 4. In saponin skinned ventricular cells: (a) L-294 present in the period of sarcoplasmic reticulum (SR) loading with Ca(2+) shifted the dose and caffeine-induced contracture curve; (b) L-294 (100 microM) increased 40% the Ca(2+) uptake into SR; (c) L-294 did not significantly alter the sensitivity of contractile proteins to Ca(2+) in SR-disrupted skinned ventricular cells. 5. Retrograde perfusion of the isolated heart from Wistar rats with L-294 (100 microM) did not cause any significant change in rhythm, heart rate (control, 220+/-14.7 b.p.m.; 246+/-24.6 b.p.m. for L-294), PR interval (control, 66.0+/-2.4 ms; 64.0+/-2.3 ms for L-294) or QRS duration (control, 28.8+/-3.4 ms; 32.0+/-2.0 ms for L-294). 6. These results suggest a novel mechanism for a positive cardioinotropic effect through an interaction with the Ca(2+) uptake/release process of the SR. The effect of L-294 could be explained by a pronounced increased accumulation of Ca(2+) into the SR.