Intravenous inotropic agents in the intensive therapy unit: do they really make a difference?

Omecamtiv Mecarbil in the treatment of heart failure: the past, the present, and the future

Heart failure, a prevailing global health issue, imposes a substantial burden on both healthcare systems and patients worldwide. With an escalating prevalence of heart failure, prolonged survival rates, and an aging demographic, an increasing number of individuals are progressing to more advanced phases of this incapacitating ailment. Against this backdrop, the quest for pharmacological agents capable of addressing the diverse subtypes of heart failure becomes a paramount pursuit. From this viewpoint, the present article focuses on Omecamtiv Mecarbil (OM), an emerging chemical compound said to exert inotropic effects without altering calcium homeostasis. For the first time, as a review, the present article uniquely started from the very basic pathophysiology of heart failure, its classification, and the strategies underpinning drug design, to on-going debates of OM's underlying mechanism of action and the latest large-scale clinical trials. Furthermore, we not only saw the advantages of OM, but also exhaustively summarized the concerns in sense of its effects. These of no doubt make the present article the most systemic and informative one among the existing literature. Overall, by offering new mechanistic insights and therapeutic possibilities, OM has carved a significant niche in the treatment of heart failure, making it a compelling subject of study.

Levosimendan improves renal function in acute decompensated heart failure: possible underlying mechanisms

AIMS

The cardio-renal syndrome plays a critical role in acute heart failure (HF). Levosimendan, an inodilator drug, has a positive but controversial effect on kidney. Our aim was to evaluate its effects on both renal and systemic haemodynamic parameters as well as on renal function, explaining the possible mechanisms involved.

METHODS AND RESULTS

Patients with acute decompensated HF, moderate renal impairment, wedge pressure >20 mmHg and EF <40% were eligible. Twenty-one patients were randomized to infusion of levosimendan or placebo, on top of standard therapy. Systemic haemodynamic parameters (wedge and cardiac output) were evaluated at baseline and at 8, 16, 24, 48, and 72 h. An intravascular renal artery Doppler exam was performed at baseline, after levosimendan bolus, and 1 h thereafter. Renal blood flow, glomerular filtration rate (GFR), cystatin C, blood urea nitrogen (BUN), urinary output, sodium excretion, and plasma sodium were measured. The effect of levosimendan was beneficial and significantly different from placebo on several renal and cardiac parameters. Specifically, the levosimendan and placebo group exhibited significantly different changes over time in GFR (P = 0.037), renal blood flow (P = 0.037), and renal artery diameter (P = 0.033), with ensuing improvements in serum levels of BUN (P = 0.014), creatinine (P = 0.042), and cystatin C (P = 0.05). Concomitantly, levosimendan provided a significant increase in urine output up to 72 h (P = 0.02). These beneficial results on renal parameters were accompanied by similarly significant and favourable changes in cardiac index (P = 0.029) and PCWP (P < 0.001).

CONCLUSION

Levosimendan, in acute decompensated HF, has an immediate renoprotective effect, mediated by an increase in renal blood flow, due to a selective renal arterial and venous vasodilating action.

TRIAL REGISTRATION

NCT00527059.

Activation of β-adrenoceptors by dobutamine may induce a higher expression of peroxisome proliferator-activated receptors δ (PPARδ) in neonatal rat cardiomyocytes

Recent evidence showed the role of peroxisome proliferator-activated receptors (PPARs) in cardiac function. Cardiac contraction induced by various agents is critical in restoring the activity of peroxisome proliferator-activated receptors δ (PPARδ) in cardiac myopathy. Because dobutamine is an agent widely used to treat heart failure in emergency setting, this study is aimed to investigate the change of PPARδ in response to dobutamine. Neonatal rat cardiomyocytes were used to examine the effects of dobutamine on PPARδ expression levels and cardiac troponin I (cTnI) phosphorylation via Western blotting analysis. We show that treatment with dobutamine increased PPARδ expression and cTnI phosphorylation in a time- and dose-dependent manner in neonatal rat cardiomyocytes. These increases were blocked by the antagonist of β1-adrenoceptors. Also, the action of dobutamine was related to the increase of calcium ions and diminished by chelating intracellular calcium. Additionally, dobutamine-induced action was reduced by the inhibition of downstream messengers involved in this calcium-related pathway. Moreover, deletion of PPARδ using siRNA generated the reduction of cTnI phosphorylation in cardiomyocytes treated with dobutamine. Thus, we concluded that PPARδ is increased by dobutamine in cardiac cells.

Levosimendan: a unique approach to the treatment of heart failure

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