Effect of a selective aldosterone receptor antagonist in myocardial infarction

Aldosterone and cardiovascular diseases

Aldosterone's role in the kidney and its pathophysiologic actions in hypertension are well known. However, its role or that of its receptor [minieralocorticoid receptor (MR)] in other cardiovascular (CV) disease are less well described. To identify their potential roles in six CV conditions (heart failure, myocardial infarction, atrial fibrillation, stroke, atherosclerosis, and thrombosis), we assessed these associations in the following four areas: (i) mechanistic studies in rodents and humans; (ii) pre-clinical studies of MR antagonists; (iii) clinical trials of MR antagonists; and (iv) genetics. The data were acquired from an online search of the National Library of Medicine using the PubMed search engine from January 2011 through June 2021. There were 3702 publications identified with 200 publications meeting our inclusion and exclusion criteria. Data strongly supported an association between heart failure and dysregulated aldosterone/MR. This association is not surprising given aldosterone/MR's prominent role in regulating sodium/volume homeostasis. Atrial fibrillation and myocardial infarction are also associated with dysregulated aldosterone/MR, but less strongly. For the most part, the data were insufficient to determine whether there was a relationship between atherosclerosis, stroke, or thrombosis and aldosterone/MR dysregulation. This review clearly documented an expanding role for aldosterone/MR's dysregulation in CV diseases beyond hypertension. How expansive it might be is limited by the currently available data. It is anticipated that with an increased focus on aldosterone/MR's potential roles in these diseases, additional clinical and pre-clinical data will clarify these relationships, thereby, opening approaches to use modulators of aldosterone/MR's action to more precisely treat these CV conditions.

New Perspectives on Sex Steroid and Mineralocorticoid Receptor Signaling in Cardiac Ischemic Injury

The global burden of ischemic heart disease is burgeoning for both men and women. Although advances have been made, the need for new sex-specific therapies targeting key differences in cardiovascular disease outcomes in men and women remains. Mineralocorticoid receptor directed treatments have been successfully used for blood pressure control and heart failure management and represent a potentially valuable therapeutic option for ischemic cardiac events. Clinical and experimental data indicate that mineralocorticoid excess or inappropriate mineralocorticoid receptor (MR) activation exacerbates ischemic damage, and many of the intracellular response pathways activated in ischemia and subsequent reperfusion are regulated by MR. In experimental contexts, where MR are abrogated genetically or mineralocorticoid signaling is suppressed pharmacologically, ischemic injury is alleviated, and reperfusion recovery is enhanced. In the chronic setting, mineralocorticoid signaling induces fibrosis, oxidative stress, and inflammation, which can predispose to ischemic events and exacerbate post-myocardial infarct pathologies. Whilst a range of cardiac cell types are involved in mineralocorticoid-mediated regulation of cardiac function, cardiomyocyte-specific MR signaling pathways are key. Selective inhibition of cardiomyocyte MR signaling improves electromechanical resilience during ischemia and enhances contractile recovery in reperfusion. Emerging evidence suggests that the MR also contribute to sex-specific aspects of ischemic vulnerability. Indeed, MR interactions with sex steroid receptors may differentially regulate myocardial nitric oxide bioavailability in males and females, potentially determining sex-specific post-ischemic outcomes. There is hence considerable impetus for exploration of MR directed, cell specific therapies for both women and men in order to improve ischemic heart disease outcomes.

The Role of Natural Killer (NK) Cells in Acute Coronary Syndrome: A Comprehensive Review

With poor outcomes and an immense financial burden, acute coronary syndrome (ACS) and its ischemic repercussions still present a major global health problem. Unfavorable outcomes seem to be mainly due to adverse cardiac remodeling. Since the inflammatory response takes an important role in remodeling secondary to myocardial infarction (MI), and as inflammation in this manner has not been completely elucidated, we attempted to give rise to a further understanding of ACS pathophysiology. Hence, in this review, we integrated current knowledge of complex communication networks between natural killer (NK) cells and immune and resident heart cells in the context of ACS. Based on available data, the role of NK cells seems to be important in the infarcted myocardium, where it affects heart remodeling. On the other hand, in atherosclerotic plaque, NK cells seem to be mere passers-by, except in the case of chronic infections by atherogenic pathogens. In that case, NK cells seem to support proinflammatory milieu. NK cell research is challenging due to ethical reasons, convergent evolution, and phenotypic diversity among individuals. Therefore, we argue that further research of NK cells in ACS is valuable, given their therapeutic potential in improving postischemic heart remodeling.

Eplerenone inhibits aldosterone-induced CRP generation in rat vascular smooth muscle cells by regulating the MR-ROS-ERK1/2 signal pathway

Atherosclerosis is a chronic inflammatory disease in the vessel wall. As a representative inflammatory cytokine, C-reactive protein (CRP) participates in the formation and development of atherosclerosis. It is demonstrated that aldosterone induces CRP generation in vascular smooth muscle cells (VSMCs). This study explored the inhibitory effect of eplerenone on aldosterone-induced CRP expression in VSMCs and mechanism. In the in vitro experiments, rat VSMCs were cultured and aldosterone (10 nM) was used as a stimulant for CRP generation. VSMCs were pretreated with eplerenone for 1 h prior to the stimulation. Messenger RNA (mRNA) and protein expression were identified by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot, respectively. The production of reactive oxygen species (ROS) was observed by a fluorescence microscope. In the in vivo experiment, a model of hyperaldosteronism was established by the subcutaneous administration of aldosterone to rats with the osmotic minipumps for 4 weeks. Serum aldosterone and CRP levels were determined with a radioimmunoassay and ELISA (enzyme-linked immunosorbent assay), respectively. The results showed that eplerenone inhibited aldosterone-induced mRNA and protein expression of CRP in VSMCs in vitro and in vivo, and decreased the circulating CRP level of hyperaldosteronism rats. Meanwhile, eplerenone reduced aldosterone-stimulated ROS generation and aldosterone-activated ERK1/2 phosphorylation in VSMCs. In summary, eplerenone inhibits aldosterone-induced CRP generation in VSMCs by regulating the MR-ROS-ERK1/2 signal pathway. These results provide new evidence for the potential anti-inflammatory effect of eplerenone.

Eplerenone — A Novel Selective Aldosterone Blocker

OBJECTIVE:

To review the pharmacology, pharmacokinetics, clinical efficacy, and safety of eplerenone, a new selective aldosterone blocker.

DATA SOURCES:

Primary literature and review articles were obtained via MEDLINE search (1966–April 2002). Additional studies and abstracts were identified from the bibliographies of reviewed literature.

STUDY SELECTION AND DATA EXTRACTION:

Studies and review articles related to eplerenone, aldosterone, aldosterone antagonist, and spironolactone were reviewed. Data pertinent to this article were included.

DATA SYNTHESIS:

Eplerenone is a selective aldosterone blocker. Recent data have demonstrated the deleterious effects of aldosterone in several chronic disease states including hypertension and heart failure. Animal studies using eplerenone have shown a positive role for aldosterone antagonism in the treatment of hypertension, heart failure, myocardial infarction, renal disease, and atherosclerosis. In humans, eplerenone appears to be effective for the treatment of hypertension. An ongoing study will examine the effect of eplerenone for heart failure. To date, the incidence of adverse effects with eplerenone has been slightly lower than with spironolactone.

CONCLUSIONS:

Eplerenone appears to be a promising drug in a new class of agents called selective aldosterone blockers. The drug may be approved for treatment of hypertension in 2002. Additional studies are ongoing that may provide information on other clinical uses for this medication.

Finerenone, a novel selective nonsteroidal mineralocorticoid receptor antagonist protects from rat cardiorenal injury

Pharmacological blockade of the mineralocorticoid receptor (MR) ameliorates end-organ damage in chronic heart failure. However, the clinical use of available steroidal MR antagonists is restricted because of concomitant hyperkalemia especially in patients with diminished kidney function. We have recently identified a novel nonsteroidal MR antagonist, finerenone, which uniquely combines potency and selectivity toward MR. Here, we investigated the tissue distribution and chronic cardiorenal end-organ protection of finerenone in comparison to the steroidal MR antagonist, eplerenone, in 2 different preclinical rat disease models. Quantitative whole-body autoradiography revealed that [C]-labeled finerenone equally distributes into rat cardiac and renal tissues. Finerenone treatment prevented deoxycorticosterone acetate-/salt-challenged rats from functional as well as structural heart and kidney damage at dosages not reducing systemic blood pressure. Finerenone reduced cardiac hypertrophy, plasma prohormone of brain natriuretic peptide, and proteinuria more efficiently than eplerenone when comparing equinatriuretic doses. In rats that developed chronic heart failure after coronary artery ligation, finerenone (1 mg·kg·d), but not eplerenone (100 mg·kg·d) improved systolic and diastolic left ventricular function and reduced plasma prohormone of brain natriuretic peptide levels. We conclude that finerenone may offer end-organ protection with a reduced risk of electrolyte disturbances.

Finerenone : third-generation mineralocorticoid receptor antagonist for the treatment of heart failure and diabetic kidney disease

INTRODUCTION

The mineralocorticoid receptor antagonists (MRAs) spironolactone and eplerenone reduce the risk of hospitalizations and mortality in patients with heart failure (HF) with reduced ejection fraction (HFrEF), and attenuate progression of diabetic kidney disease. However, their use is limited by the fear of inducing hyperkalemia, especially in patients with renal dysfunction. Finerenone is a novel nonsteroidal MRA, with higher selectivity toward the mineralocorticoid receptor (MR) compared to spironolactone and stronger MR-binding affinity than eplerenone.

AREAS COVERED

This paper discusses the chemistry, pharmacokinetics, clinical efficacy and safety of finerenone.

EXPERT OPINION

The selectivity and greater binding affinity of finerenone to the MR may reduce the risk of hyperkalemia and renal dysfunction and thereby overcome the reluctance to start and uptitrate MRAs in patients with HF and diabetic kidney disease. Studies conducted in patients with HFrEF and moderate chronic kidney disease and diabetic kidney disease, showed promising results. Phase III trials will have to show whether finerenone might become the third-generation MRA for the treatment of HF and diabetic kidney disease.

Mineralocorticoid receptor antagonist in heart failure: Past, present and future perspectives

Aldosterone is involved in various deleterious effects on the cardiovascular system, including sodium and fluid retention, myocardial fibrosis, vascular stiffening, endothelial dysfunction, catecholamine release and stimulation of cardiac arrhythmias. Therefore, aldosterone receptor blockade may have several potential benefits in patients with cardiovascular disease. Mineralocorticoid receptor antagonists (MRAs) have been shown to prevent many of the maladaptive effects of aldosterone, in particular among patients with heart failure (HF). Randomized controlled trials have demonstrated efficacy of MRA in heart failure with reduced ejection fraction, both in patients with NYHA functional classes III and IV and in asymptomatic and mildly symptomatic patients (NYHA classes I and II). Recent data in patients with heart failure with preserved ejection fraction are encouraging. MRA could also have anti-arrhythmic effects on atrial and ventricular arrhythmias and may be helpful in patient ischemic heart disease through prevention of myocardial fibrosis and vascular damage. This article aims to discuss the pathophysiological effects of aldosterone in patients with cardiovascular disease and to review the current data that support the use of MRA in heart failure.

The cardioprotective effects of mineralocorticoid receptor antagonists

Despite state-of-the-art reperfusion therapy, morbidity and mortality remain significant in patients with an acute myocardial infarction. Therefore, novel strategies to limit myocardial ischemia-reperfusion injury are urgently needed. Mineralocorticoid receptor (MR) antagonists are attractive candidates for this purpose, since several clinical trials in patients with heart failure have reported a survival benefit with MR antagonist treatment. MRs are expressed by several cells of the cardiovascular system, including cardiomyocytes, cardiac fibroblasts, vascular smooth muscle cells, and endothelial cells. Experiments in animal models of myocardial infarction have demonstrated that acute administration of MR antagonists, either before ischemia or immediately at the moment of coronary reperfusion, limits infarct size. This action appears to be independent of the presence of aldosterone and cortisol, which are the endogenous ligands for the MR. The cardioprotective effect is mediated by a nongenomic intracellular signaling pathway, including adenosine receptor stimulation, and activation of several components of the Reperfusion Injury Salvage Kinase (RISK) pathway. In addition to limiting infarct size, MR antagonists can improve scar healing when administered shortly after reperfusion and can reduce cardiac remodeling post myocardial infarction. Clinical trials are currently being performed studying whether early administration of MR antagonists can indeed improve prognosis in patients with an acute myocardial infarction, independent of the presence of heart failure.

Mineralocorticoid receptor activation in myocardial infarction and failure: recent advances

The classical view of aldosterone actions via the mineralocorticoid receptor (MR) limited to control of fluid balance and blood pressure homoeostasis has been progressively overcome by clinical and experimental evidence emphasizing the pleiotropic role of MR activation in the pathogenesis of cardiovascular disease. Clinical studies have shown the benefit of MR blockade in patients with left ventricular dysfunction and heart failure after myocardial infarction (MI), hypertension or diabetic nephropathy. Deleterious effects of MR activation include cardiac structural and electrical remodelling, cardiovascular fibrosis, inflammation and oxidative stress. Complexity of pathophysiological role of MR derives from the presence of circulating glucocorticoids at higher concentrations than aldosterone and the equal affinity of the MR for aldosterone, cortisol and corticosterone. Recent experimental studies using different animal models and genetic tools have deeply explored the cell-specific functional role of MR in cardiovascular pathology. This review addresses emerging preclinical studies as well as ongoing clinical trials regarding MR activation in MI and failure.

Molecular pharmacology of the mineralocorticoid receptor: prospects for novel therapeutics

The blockade of mineralocorticoid receptors (MR) has been shown to be an invaluable therapy in heart failure and hypertension. To date, only two steroidal antimineralocorticoids, spironolactone (and its active metabolite canrenone) and eplerenone, have been approved, whereas novel non-steroidal compounds are in preclinical and early development. The careful investigation of the efficacy and tolerance of spironolactone in essential hypertension initially supported the idea that a more selective second generation of MR antagonists is desired for chronic treatment of cardiovascular diseases. More than 40 years went by between the approval of the first MR antagonist spironolactone and the market introduction of its sole successor, eplerenone. The molecular pharmacology of MR antagonists may be addressed at different levels. Available preclinical and clinical data of the two approved steroidal antimineralocorticoids allow a good comparison of potency and selectivity of MR antagonists and their pharmacokinetic properties. The search for novel generations of MR antagonists with the ultimate goal of a more tissue selective mode of action may require novel compounds that are differentiated with respect to the binding mode to the MR. Other factors that may contribute to tissue selectivity as e.g. the physicochemical properties of a drug and how they influence the resulting pharmacology in the context of tissue selective co-factor expression are even less well understood. In the following we will review these aspects and demonstrate that the molecular pharmacology of current MR antagonists is on the one hand far from well understood and, on the other hand, still offers room for improvements.

Postinfarction healing dynamics in the mechanically unloaded rat left ventricle

The healing process is a key determinant for postinfarction left ventricular (LV) remodeling and the development of heart failure, which could be influenced by mechanical (pressure and/or volume) load. So far, limited information exists regarding an indepth characterization of the postinfarct healing process in the mechanically unloaded state. In the present work, we performed isogenic Lewis-to-Lewis rat abdominal heterotopic heart transplantation, which is characterized by hemodynamic unloading in the left ventricle, and simultaneously ligated the left anterior descending coronary artery (T-infarct group). Pathological evolution was dynamically compared with that of in situ infarcted Lewis hearts (I-infarct group) on days 3, 7, 14, and 35. There was a remarkable myocardial salvage in the unloaded heart, as shown by the improvement in infarct size (T-infarct group: 25.47% ± 4.31% vs. I-infarct group: 38.46% ± 4.82%, P < 0.01) and the smaller fraction of fibrosis in infarct segments (T-infarct group: 42.12% ± 8.40% vs. I-infarct group: 75.65% ± 10.51%, P < 0.01). In addition, there was a progressive disorganization of the two-dimensional collagen fiber alignment as well as retarded collagen fiber maturation in the T-infarct group. We also observed enhanced angiogenesis, lymphangiogenesis, and inflammatory cell retention in the infarct region during mechanical unloading. Moreover, capillary density and collagen deposition were significantly increased in the noninfarcted area of the unloaded heart compared with the same region in the in situ infarcted heart. In conclusion, ischemic insult in the mechanically unloaded heart elicits an altered inflammatory and healing response, which is characterized by myocardial salvage, delayed resolution of inflammation, and disorganization of the collagen orientation in the infarcted region. These findings could provide novel insights into the contribution of hemodynamic load in the postinfarction healing process. Further studies are warranted to elucidate its potential mechanism.

Aortocaval fistula in rat: a unique model of volume-overload congestive heart failure and cardiac hypertrophy

Despite continuous progress in our understanding of the pathogenesis of congestive heart failure (CHF) and its management, mortality remains high. Therefore, development of reliable experimental models of CHF and cardiac hypertrophy is essential to better understand disease progression and allow new therapy developement. The aortocaval fistula (ACF) model, first described in dogs almost a century ago, has been adopted in rodents by several groups including ours. Although considered to be a model of high-output heart failure, its long-term renal and cardiac manifestations are similar to those seen in patients with low-output CHF. These include Na⁺-retention, cardiac hypertrophy and increased activity of both vasoconstrictor/antinatriureticneurohormonal systems and compensatory vasodilating/natriuretic systems. Previous data from our group and others suggest that progression of cardiorenal pathophysiology in this model is largely determined by balance between opposing hormonal forces, as reflected in states of CHF decompensation that are characterized by overactivation of vasoconstrictive/Na⁺-retaining systems. Thus, ACF serves as a simple, cheap, and reproducible platform to investigate the pathogenesis of CHF and to examine efficacy of new therapeutic approaches. Hereby, we will focus on the neurohormonal, renal, and cardiac manifestations of the ACF model in rats, with special emphasis on our own experience.

Association of ST2 levels with cardiac structure and function and mortality in outpatients

BACKGROUND

ST2, an interleukin-1 receptor family member up-regulated in the setting of cardiomyocyte strain, has prognostic value in patients with acute myocardial infarction, chronic severe heart failure, and acute heart failure. The predictive value of ST2 levels in outpatients is unknown. We studied the clinical and echocardiographic correlates of ST2 levels and evaluated their prognostic use in outpatients referred for echocardiograms.

METHODS

ST2 levels were measured in 588 outpatients referred for echocardiogram. Subjects were analyzed by quartile as well as by optimal ST2 cut-point (28.25 ng/mL) derived from receiver operating characteristic curve analysis. All-cause death at 1 year was the primary outcome.

RESULTS

In this cohort with mean age of 68 ± 12 years and median ST2 level of 19.8 ng/mL (interquartile range 15.8-23.7), 25 deaths occurred. Heart rate, creatinine clearance, use of diuretics, and the presence of right ventricular hypokinesis were independently associated with ST2 levels. At 6 months, no patients with ST2 below the median had died. Patients with high ST2 levels had an increased risk of death (adjusted hazard ratio [HR] 2.5, P = .02); those with elevated levels of both ST2 and B-type natriuretic peptide were at even higher risk (adjusted HR 4.3, P = .01 vs none elevated).

CONCLUSIONS

ST2 levels reflect right-side heart size and function and are independent predictors of 1-year mortality in outpatients referred for echocardiograms. The optimal cut-point derived in this cohort is comparable with the previously identified prognostic cut-point for sicker patients. ST2 may be an especially strong prognostic marker for short-term mortality risk.

Timing of eplerenone initiation and outcomes in patients with heart failure after acute myocardial infarction complicated by left ventricular systolic dysfunction: insights from the EPHESUS trial

AIMS

To test the hypothesis that an earlier post-acute myocardial infarction (AMI) eplerenone initiation in patients with left ventricular systolic dysfunction (LVSD) and heart failure (HF) is associated with better long-term outcomes.

METHODS AND RESULTS

The 6632 patients of the EPHESUS study were randomized from day 3 to 14 after the index AMI (median = 7 days), of these 3319 were assigned to eplerenone. We analysed the differential effects of time-to-eplerenone initiation vs. placebo, based on the median time to initiation of treatment (<7 days-'earlier', > or =7days-'later'). Effects on outcomes were evaluated over a mean 16-month follow-up, using Cox proportional hazards regression analysis. The earlier eplerenone initiation (<7 days) reduced the risk of all-cause mortality by 31% (P = 0.001) when compared with the 'earlier' placebo' and also reduced the risks of cardiovascular (CV) hospitalization/CV mortality by 24% (P < 0.0001) and sudden cardiac death (SCD) by 34% (P < 0.0001). In contrast, later eplerenone initiation (> or =7 days) had no significant effect on outcomes. Interactions between time-to-randomization and treatment were significant. These associations remained substantially unchanged after risk adjustment in multivariable models.

CONCLUSION

An earlier eplerenone administration (3-7days) post-AMI improved outcomes in patients with LVSD and HF. This benefit was not observed when eplerenone was initiated later (> or =7days).

Left ventricular remodeling after acute myocardial infarction: does eplerenone have an effect?

AIMS

Aldosterone antagonism reduces cardiovascular morbidity and mortality in patients with left ventricular (LV) systolic dysfunction and heart failure or diabetes after acute myocardial infarction (AMI). The mechanism of this effect is unclear. We performed a contrast-enhanced cardiac magnetic resonance study to assess the effects of eplerenone on LV remodeling after AMI.

METHODS

One hundred patients (mean age, 58.9 +/- 12 years; 77% male) with LV systolic dysfunction but without heart failure or diabetes were randomized to 24 weeks' double-blind treatment with eplerenone or placebo started 1 to 14 days after AMI. Contrast-enhanced cardiac magnetic resonance was performed, and plasma concentrations of matrix metalloproteinase-2 (MMP-2) and MMP-9 were measured before randomization and at 12 and 24 weeks.

RESULTS

Baseline LV ejection fraction was, by chance, significantly higher in eplerenone than in placebo-treated patients. Eplerenone had no effect on the primary end point (change in LV end-systolic volume index); after covariate adjustment, the primary end point fell by 6.1 +/- 2.7 mL/m2 with eplerenone compared to placebo (P = .027), and LV end-diastolic volume index fell by 7.5 +/- 3.4 mL/m2 (P = .031); eplerenone did not significantly influence LV ejection fraction. Eplerenone, after covariate adjustment, significantly decreased MMP-2 and increased MMP-9 over 24 weeks relative to placebo.

CONCLUSIONS

In a population of patients with AMI with high uptake of contemporary antiremodeling therapy, eplerenone provides modest incremental protection against LV remodeling, only after covariate adjustment.

Sex-specific impact of aldosterone receptor antagonism on ventricular remodeling and gene expression after myocardial infarction

Aldosterone receptor antagonism reduces mortality and improves post-myocardial infarction (MI) remodeling. Because aldosterone and estrogen signaling pathways interact, we hypothesized that aldosterone blockade is sex-specific. Therefore, we investigated the impact of eplerenone on left ventricular (LV) remodeling and gene expression of male infarcted rats versus female infarcted rats. MI and Sham animals were randomized to receive eplerenone (100 mg/kg/day) or placebo 3 days post-surgery for 4 weeks and assessed by echocardiography. In the MI placebo group, left ventricular end-diastolic dimension (LVEDD) increased from 7.3 +/- 0.4 mm to 10.2 +/- 1.0 mm (p < 0.05) and ejection fraction (EF) decreased from 82.3 +/- 4% to 45.5 +/- 11% (p < 0.05) in both sexes (p = NS between groups). Eplerenone attenuated LVEDD enlargement more effectively in females (8.8 +/- 0.2 mm, p < 0.05 vs. placebo) than in males (9.7 +/- 0.2 mm, p = NS vs. placebo) and improved EF in females (56.7 +/- 3%, p < 0.05 vs. placebo) but not in males (50.6 +/- 3%, p = NS vs. placebo). Transcriptomic analysis using Rat_230-2.0 microarrays (Affymetrix) revealed that in females 19% of downregulated genes and 44% of upregulated genes post-MI were restored to normal by eplerenone. In contrast, eplerenone only restored 4% of overexpressed genes in males. Together, these data suggest that aldosterone blockade reduces MI-induced cardiac remodeling and phenotypic alterations of gene expression preferentially in females than in males. The use of transcriptomic signatures to detect greater benefit of eplerenone in females has potential implications for personalized medicine.

Aldosterone receptor antagonism and heart failure: insights from an outpatient clinic

OBJECTIVE

In randomized clinical trials, aldosterone antagonists have been shown to reduce mortality and morbidity in heart failure (HF). The aim of the present study was to examine the risk-benefit profile of aldosterone antagonists in routine clinical practice.

METHODS

A retrospective analysis, extending over a 1-year period, of the clinical, instrumental and laboratory data of 264 HF outpatients was performed. All patients were on a beta-blocker and an ACE-inhibitor (or angiotensin-II receptor-blocker) and 151 were taking an aldosterone antagonist.

RESULTS

At baseline, subjects treated with aldosterone antagonists had a higher NYHA class, a larger left-ventricular end-diastolic volume, a worse ejection fraction and a higher systolic pulmonary arterial pressure (sPAP). During follow-up, a greater reduction in sPAP and a tendency towards improved systolic and diastolic function were observed in subjects treated with aldosterone antagonists. Moreover, clinical and laboratory parameters did not deteriorate in patients taking aldosterone antagonists. Mortality rates were similar in the two groups (8.6% vs. 8.8%, P = NS).

CONCLUSIONS

The use of aldosterone antagonists in HF is associated with an improvement in cardiac function and is well tolerated. In the present study, patients administered these agents had a comparable clinical outcome to that of the control group, despite important differences in baseline risk.

Immediate mineralocorticoid receptor blockade improves myocardial infarct healing by modulation of the inflammatory response

Mineralocorticoid receptor (MR) blockade reduces morbidity and mortality after acute myocardial infarction; however, the underlying mechanisms are still under investigation. This study examined whether MR antagonism promotes healing of the infarcted myocardium. Starting immediately after coronary ligation, male Wistar rats were treated with the selective MR antagonist eplerenone (100 mg/kg per day by gavage) or placebo for 2 to 7 days. At 7 days, eplerenone therapy versus placebo significantly reduced thinning and dilatation of the infarcted wall, improved left ventricular function, and enhanced neovessel formation in the injured myocardium. At 2 days, eplerenone-treated rats displayed lower plasma corticosterone levels, higher circulating blood monocytes, and more macrophages infiltrating the infarcted myocardium. MR blockade led to a transient upregulation (at days 2 and 3 but not at day 7) of monocyte chemoattractant protein-1, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-10, and interleukin-4 and an increase in factor XIIIa protein expression in the healing myocardium. Prevention of macrophage accumulation into the infarct zone by treatment with liposome-encapsulated clodronate almost abrogated the protein expression of factor XIIIa and the beneficial effects of eplerenone on infarct expansion. In conclusion, selective MR blockade immediately after myocardial infarction accelerated macrophage infiltration and transiently increased the expression of healing promoting cytokines and factor XIIIa in the injured myocardium resulting in enhanced infarct neovascularization and reduced early LV dilation and dysfunction.

Aldosterone induces elastin production in cardiac fibroblasts through activation of insulin-like growth factor-I receptors in a mineralocorticoid receptor-independent manner

Aldosterone is known to regulate electrolyte homeostasis, but it may also contribute to other processes, including the maladaptive remodeling of postinfarct hearts. Because aldosterone has been implicated in the stimulation of collagen production in the heart, we investigated whether it would also affect elastin deposition in cultures of human cardiac fibroblasts. We first demonstrated that treatment with 1 to 50 nmol/L aldosterone leads to a significant increase in collagen type I mRNA levels and in subsequent collagen fiber deposition. Pretreatment of cells with the mineralocorticoid receptor antagonist spironolactone, but not with the glucocorticoid receptor antagonist RU 486, inhibited collagen synthesis in aldosterone-treated cultures. Most importantly, we demonstrated that aldosterone also increases elastin mRNA levels, tropoelastin synthesis, and elastic fiber deposition in a dose-dependent manner. Strikingly, neither spironolactone nor RU 486 eliminated aldosterone-induced increases in elastin production. We further discovered that the proelastogenic effect of aldosterone involves a rapid increase in tyrosine phosphorylation of the insulin-like growth factor-I receptor and that the insulin-like growth factor-I receptor kinase inhibitor AG1024 or an anti-insulin-like growth factor-I receptor-neutralizing antibody inhibits both insulin-like growth factor-I and aldosterone-induced elastogenesis. Thus, we have demonstrated for the first time that aldosterone, which stimulates collagen production through the mineralocorticoid receptor-dependent pathway, also increases elastogenesis via a parallel mineralocorticoid receptor-independent pathway involving I insulin-like growth factor-I receptor signaling.

Aldosterone as a cardiovascular risk hormone

The pathophysiological role of aldosterone in the development of cardiovascular disease has long been considered to be due its potent volume expansion/hypertensive effect mainly via mineralocorticoid receptor (MR) expressed in renal tubular epithelial cells. However, recent accumulating lines of evidence from clinical and experimental studies have suggested that direct cardiovascular effect of aldosterone contributes to the development of cardiovascular injury via MRs in non-epithelial tissue. A series of recent clinical studies have revealed that patients with primary aldosteronism have higher incidence of cardiovascular and renal complications than those with essential hypertension, and that aldosterone antagonism has cardiovascular protective effect in patients with heart failure independent from blood pressure. Numerous experimental studies have shown that both inflammation and oxidative stress play an initial and key role in the development of aldosterone-induced cardiovascular injury via non-epithelial MR activation. In this review, we discuss recent research progress in aldosterone and MR effects, with special emphasis on the pathophysiological role of aldosterone in cardiovascular diseases and the possible molecular mechanism(s) of cardiovascular injury by non-epithelial MR activation.

Reversing chronic remodeling in heart failure

Chronic heart failure is a debilitating condition with significant morbidity, mortality and an increasing economic burden. The past 20 years have witnessed great strides in both medical and device-based therapies for heart failure. Central to these developments has been the ability to favorably reverse the chronic processes by which the failing heart remodels. In addition to pharmacotherapies, such as beta-blockade, and inhibition of the renin-angiotensin-aldosterone system, surgical remodeling, containment devices and new methods to restore synchronous contraction have been added to the armamentarium, in some instances, providing clear improvement to both symptoms and mortality. In more advanced stages of heart failure, left ventricular-assist devices provide marked unloading of the failing ventricle and such therapy has provided unique insights into the molecular and cellular mechanisms underlying reverse remodeling, given the immediate access to cardiac tissue. Genetic and cellular approaches, as well as new small molecule targets, may provide future avenues for reverse remodeling of the failing heart, improving symptoms and disease outcome.

Mineralocorticoid receptor antagonists

With an increasingly aging population, the need for effective treatment of cardiovascular diseases (eg, heart failure, hypertension, and ischemic heart disease) cannot be overemphasized. The vital importance of mineralocorticoid receptor antagonists for treating cardiovascular conditions has only been appreciated in the last decade. The re-emergence of mineralocorticoid receptor antagonists has provided clinicians with an important tool towards complete blockade of the renin-angiotensin-aldosterone axis.

Effects of eplerenone and salt intake on left ventricular remodeling after myocardial infarction in rats

Eplerenone, a selective aldosterone blocker, has been shown to attenuate cardiac fibrosis and decrease cardiovascular events in both experimental and clinical studies. We examined the cardioprotective effect of eplerenone in myocardial infarction (MI) rats receiving different levels of salt in their diet. The MI rats were randomly divided into five groups: Group CL, animals received a low-salt diet (0.015%); Group EpL, a low-salt diet with eplerenone (100 mg/kg/day in food); Group CH, a high-salt diet (0.9%); Group EpH, a high-salt diet with eplerenone; and Group C, a normal salt diet (0.3%). These diets were continued for 4 weeks. Echocardiographic and histomorphological examinations revealed that the administration of eplerenone significantly improved the cardiac function, significantly suppressed compensatory cardiac hypertrophy and significantly reduced cardiac fibrosis in both the interstitial and the perivascular areas in the high-salt diet group (Group EpH). However, eplerenone had no observable effects in the low-salt diet group (Group EpL). Also, these examinations demonstrated that the left ventricular remodeling after MI was suppressed and the cardiac function was improved in the group receiving a low-salt diet without eplerenone (Group CL), even though there was a significant increase of aldosterone level in blood, in comparison to the group receiving a high-salt diet without eplerenone (Group CH). These results indicate that the cardioprotective effect of eplerenone varies depending on the salt intake.

Spironolactone Modulates Expressions of Cardiac Mineralocorticoid Receptor and 11.BETA.-Hydroxysteroid Dehydrogenase 2 and Prevents Ventricular Remodeling in Post-Infarct Rat Hearts

Aldosterone antagonists have been reported to prevent ventricular remodeling after myocardial infarction (MI) via their action to extracellular matrix (ECM). However, it remains largely unknown whether aldosterone antagonists attenuate myocyte loss in the remodeling process. The present study examined whether spironolactone prevents myocyte apoptosis and improves post-infarct ventricular remodeling in rats. MI was achieved by permanent occlusion of the left coronary artery. Administration of spironolactone (100 mg/kg/day) was started immediately after MI. Sprague-Dawley rats were divided into four groups: 1) sham, 2) spironolactone-treated sham, 3) untreated MI, 4) spironolactone-treated MI. Echocardiographic parameters (left ventricular [LV] diastolic dimension [LVDd], fractional shortening [%FS]), hemodynamic parameters (LV systolic pressure [LVSP], LV end-diastolic pressure [LVEDP], dP/dt(max) and dP/dt(min)) and collagen accumulation quantitated by Masson's Trichrome staining were significantly improved in the spironolactone-treated MI group on the 14th day, compared with the untreated MI group. Moreover, the percentage of apoptotic myocytes evaluated by terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assay was significantly lower in the spironolactone-treated MI group on the 2nd (3.54% vs. 5.79% in untreated MI group), 7th (0.65% vs. 1.37% in untreated MI group) and 14th days (0.11% vs. 0.16% in untreated MI group). Real time reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the expression of mineralocorticoid receptor (MR) mRNA and that of 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2) mRNA, which is known to confer aldosterone selectivity on MR, were upregulated in the untreated MI group, and that spironolactone significantly suppressed the expression of these genes. Moreover, spironolactone significantly inhibited aldosterone-induced apoptosis in cultured rat cardiac myocytes in a dose-dependent fashion. Our study demonstrates that, in addition to their effect on ECM, aldosterone antagonists inhibit myocyte apoptosis and prevent post-infarct ventricular remodeling by modulating the expression levels of MR and 11beta-HSD2, which are enhanced in the remodeling heart.

Long-term effects of spironolactone on proteinuria and kidney function in patients with chronic kidney disease

Experimental evidence suggests that aldosterone contributes to progressive kidney disease. Angiotensin-converting enzyme inhibitors and angiotensin type 1 receptor antagonists suppress the renin-angiotensin system but they do not effectively reduce plasma aldosterone. Hence, administration of aldosterone receptor antagonists may provide additional renal protection. In the present prospective randomized open-label study, we evaluated the effects of spironolactone (25 mg/day for 1 year) on proteinuria and estimated glomerular filtration rate in 83 patients with chronic kidney disease already treated with angiotensin-converting enzyme inhibitors and/or angiotensin type 1 receptor antagonists. Eighty-two patients were treated with angiotensin-converting enzyme inhibitors and/or angiotensin type 1 receptor antagonists alone and served as controls. After 1 year of therapy, proteinuria decreased from 2.1+/-0.08 to 0.89+/-0.06 g/g creatinine (P<0.001) in patients treated with spironolactone, but it did not change in control patients. Baseline aldosterone levels were significantly correlated with proteinuria (r=0.76, P<0.0001), and predicted the degree of reduction in proteinuria with spironolactone (r=0.42, P<0.0002). Baseline estimated glomerular filtration rate was similar in patients treated with spironolactone and controls (62.4+/-2.4 and 62.2+/-2.1 ml/min/1.73 m(2), respectively). After 1 month of therapy with spironolactone, estimated glomerular filtration rate decreased more in patients treated with spironolactone than in controls. However, by the end of 1 year the monthly rate of decrease in estimated glomerular filtration rate from baseline was lower in patients treated with spironolactone than in controls (0.323+/-0.044 vs 0.474+/-0.037 ml/min/1.73 m(2), P<0.01). Spironolactone caused a significant rise in serum potassium levels (from 4.2+/-0.04 at baseline to 5.0+/-0.05 mEq/l after 12 months of treatment, P<0.001). In conclusion, this study has shown that spironolactone may reduce proteinuria and retard renal progression in chronic kidney disease patients.

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.

Neurohormones and heart failure: the importance of aldosterone

Heart failure is a major cause of cardiovascular morbidity and mortality and its incidence is on the increase. The pathophysiology of heart failure is multi-factorial but recent studies suggest that aldosterone plays an important and independent role in its progression. Emerging evidence now suggests that aldosterone exerts renal-independent effects. It binds to its mineralocorticoid receptor to produce direct effects on the myocardium and vasculature, leading to damaging processes such as hypertrophy, necrosis, fibrosis and endothelial dysfunction, factors known to contribute to the pathophysiology of heart failure. Mineralocorticoid receptor antagonists have thus emerged as a new paradigm for the treatment of heart failure. The benefits of these agents on both morbidity and mortality when used in patients with chronic symptomatic heart failure have been demonstrated by recent trials.

Cardiovascular effects of aldosterone and post-acute myocardial infarction pathophysiology

Aldosterone is an important mediator of the renin-angiotensin-aldosterone system (RAAS) that plays a major role in the pathophysiology of cardiovascular disease as well as regulation of extracellular fluid volume and potassium. In experimental models, aldosterone has been shown to promote endothelial dysfunction; induce vascular inflammation, myocardial ischemia, and necrosis; increase collagen synthesis in cardiac fibroblasts; contribute to plasminogen activator inhibitor-1 regulation; decrease baroreceptor sensitivity and reflex function; block myocardial uptake of norepinephrine; increase oxidative stress; and stimulate cardiomyocyte apoptosis. A review of animal and human studies with aldosterone blockers reveals improvement in, and in some cases complete reversal of, these pathophysiologic effects of aldosterone on the cardiovascular system.

Phenytoin can accelerate the healing process after experimental myocardial infarction?

BACKGROUND

Over-degradation and/or inadequate accumulation of extracellular matrix after myocardial infarction (MI) may lead to adverse ventricular remodeling, even ventricular aneurysm or rupture. Phenytoin can increase gingival overgrowth by stimulating the proliferation of connective tissue, which implies a novel way to hasten the healing process after MI.

METHODS

Experimental MI was induced by permanent coronary ligation. Surviving rats after MI were randomly divided into phenytoin, captopril, phenytoin plus captopril, operation control and sham operation group. Picrosirius red staining plus polarized microscopy was used for collagen analysis. Left ventricular passive pressure-volume relationship was determined ex vivo. The effects of phenytoin concentration gradient (0, 1.25, 2.5, 5.0, 10.0, and 20.0 microg/mL) on transforming growth factor-beta1 (TGF-beta1) mRNA and protein expression by neonatal rat cardiac fibroblast were determined using semi-quantitative RT-PCR and ELISA, respectively. Peritoneal macrophage was incubated with same gradient of phenytoin concentration. Then the supernatant was harvested to stimulate another 6 groups of cardiac fibroblast, to investigate possible role mediated by macrophage.

RESULTS

Phenytoin treatment could promote type I collagen cross-linking level and ratio of type I/III collagen in the infarcted region and had no obvious side effect on interstitial collagen volume fraction, subtype ratio and distribution in non-infarcted region. Phenytoin-treated hearts exhibited attenuation of global ventricular dilation. Phenytoin alone had no direct effects on rat cardiac fibroblast proliferation and collagen production in vitro, but phenytoin-stimulated macrophage could exert a positive influence on cardiac fibroblast TGF-beta1 mRNA and protein production, which exhibited a dose-dependent manner.

CONCLUSIONS

Phenytoin can accelerate the healing process in the infarcted region and has no obviously detrimental influence on collagen accumulation in non-infarcted region, which implies a potential benefit to patients undergoing early post-infarction ventricular remodeling process.

Antagonists of aldosterone and proteinuria in patients with CKD: an uncontrolled pilot study

BACKGROUND

Experimental evidence suggests that aldosterone may contribute to progressive kidney disease. Although angiotensin-converting enzyme (ACE) inhibitors and angiotensin type 1 receptor antagonists (ARBs) suppress the renin-angiotensin system, these agents do not adequately control plasma aldosterone levels. Hence, administration of aldosterone receptor antagonists may provide additional renal benefits to the ACE inhibitors and ARBs.

METHODS

In the present uncontrolled pilot study, we evaluate the short-term (8 weeks) effects of spironolactone on proteinuria in 42 patients with chronic kidney disease (CKD) already treated with ACE inhibitors and/or ARBs.

RESULTS

Spironolactone (25 mg/d for 8 weeks) decreased proteinuria from protein of 2.09 +/- 0.16 to 1.32 +/- 0.08 g/24 h after 2 weeks and 1.05 +/- 0.08 g/24 h after 8 weeks. Four weeks after discontinuation of spironolactone therapy, proteinuria returned to close to baseline values. Baseline proteinuria correlated significantly with plasma aldosterone level (r = 0.81; P < 0.0001). Moreover, baseline aldosterone level correlated significantly with degree of reduction in proteinuria after treatment with spironolactone (r = 0.70; P < 0.0001). Spironolactone caused a significant increase in serum potassium levels (from 4.4 +/- 0.1 mEq/L [mmol/L] at baseline to 4.8 +/- 0.1 mEq/L [mmol/L] after 8 weeks of treatment; P < 0.01).

CONCLUSION

This study shows that spironolactone may effectively reduce proteinuria in patients with CKD. Concerns remain in regard to the risk for hyperkalemia in patients with CKD. Prospective randomized trials are necessary to confirm the efficacy and safety of antagonists of aldosterone on proteinuria and progression of CKD.

Efficacy of aldosterone receptor antagonism in heart failure: potential mechanisms

Results of the Randomized Aldactone Evaluation Study and the Eplerenone Post-acute Myocardial Infarction Heart Failure Efficacy and Survival Study indicate aldosterone receptor antagonism, together with angiotensin-converting enzyme inhibition and loop diuretics, is a most effective strategy in reducing risk for all-cause and cardiovascular-related mortality and morbidity in patients with symptomatic heart failure. Responsible mechanisms are likely multifactoral. As a circulating hormone, aldosterone has well-known endocrine properties that contribute to the pathophysiology of congestive heart failure. This includes Na+ resorption at the expense of K+ excretion in such tissues as kidneys, colon, sweat, and salivary glands. Mg2+ excretion at these sites is likewise enhanced by aldosterone, whereas adrenal aldosterone secretion is regulated by extracellular Mg2+. Other endocrine actions of aldosterone receptor-ligand binding include: a reduction in biologically active cytosolic-free Mg2+, with intracellular Ca2+ loading in nonepithelial cells such as peripheral blood mononuclear cells; its influence on endothelial cell function; and its central actions, including the choroid plexus, activity of the hypothalamic paraventricular nucleus, and autonomic nervous system. De novo generation of aldosterone within the cardiovasculature is recognized and findings suggest its auto/paracrine properties contribute to tissue repair. Each of these actions is interrupted by aldosterone receptor antagonism and therefore may contribute to its salutary response in heart failure.

Eplerenone Reduces Mortality 30 Days After Randomization Following Acute Myocardial Infarction in Patients With Left Ventricular Systolic Dysfunction and Heart Failure

OBJECTIVES

This study sought to assess the impact of the selective aldosterone blocker eplerenone on mortality 30 days after randomization in patients after acute myocardial infarction (AMI) with a left ventricular ejection fraction (LVEF) < or =40% and clinical signs of heart failure.

BACKGROUND

In the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS), eplerenone reduced all-cause mortality by 15% (p = 0.008) over a mean follow-up of 16 months when used with standard therapy in patients after AMI with an LVEF < or =40% and clinical signs of heart failure.

METHODS

We analyzed the effect of eplerenone 25 mg/day initiated 3 to 14 days after AMI (mean, 7.3 days) on the co-primary end points of time to death from any cause and the composite end point of time to death from cardiovascular (CV) causes or hospitalization for CV events, and the secondary end points of CV mortality, sudden cardiac death, and fatal/nonfatal hospitalization for heart failure, after 30 days of therapy in the EPHESUS trial.

RESULTS

At 30 days after randomization, eplerenone reduced the risk of all-cause mortality by 31% (3.2% vs. 4.6% in eplerenone and placebo-treated patients, respectively; p = 0.004) and reduced the risk of CV mortality/CV hospitalization by 13% (8.6% vs. 9.9% in eplerenone and placebo-treated patients, respectively; p = 0.074). Eplerenone also reduced the risk of CV mortality by 32% (p = 0.003) and the risk of sudden cardiac death by 37% (p = 0.051).

CONCLUSIONS

Eplerenone 25 mg/day significantly reduced all-cause mortality 30 days after randomization (when initiated at a mean of 7.3 days after AMI) in addition to conventional therapy in patients with an LVEF < or =40% and signs of heart failure. Based on its early survival benefit, eplerenone should be administered in the hospital after AMI.

Effects of spironolactone and eprosartan on cardiac remodeling and angiotensin-converting enzyme isoforms in rats with experimental heart failure

Angiotensin-converting enzyme (ACE)-2 is a newly described enzyme with antagonistic effects to those of the classical ACE (ACE-1). Both ANG II and aldosterone play an important role in the pathophysiology of congestive heart failure (CHF) and in the adverse cardiac remodeling during its development. In this study, we examined the effects of experimental CHF induced by an aortocaval fistula (ACF) and of its treatment with ANG II and aldosterone inhibitors on the relative levels of ACE-1 and ACE-2. We also compared the effects of spironolactone, an aldosterone antagonist, and eprosartan, an ANG II receptor antagonist, on heart hypertrophy and fibrosis in rats with ACF. Spironolactone (15 mg x kg(-1) x day(-1) ip, via minipump) or eprosartan (5 mg x kg(-1) x day(-1) ip, via minipump) was administered into rats with ACF for 14 and 28 days. Specific antibodies were used to determine the protein levels of myocardial ACE-1 and ACE-2. ACF increased the cardiac levels of ACE-1 and decreased those of ACE-2. Heart-to-body weight ratio significantly increased from 0.30 +/- 0.004% in sham-operated controls to 0.50 +/- 0.018% and 0.56 +/- 0.044% (P < 0.001) in rats with ACF, 2 and 4 wk after surgery, respectively, in association with increased plasma levels of aldosterone. The area occupied by collagen increased from 2.33 +/- 0.27% to 6.85 +/- 0.65% and 8.03 +/- 0.93% (P < 0.01), 2 and 4 wk after ACF, respectively. Both spironolactone and eprosartan decreased cardiac mass and collagen content and reversed the shift in ACE isoforms. ACF alters the ratio between ACE isoforms in a manner that increases local ANG II and aldosterone levels. Early treatment with both ANG II and aldosterone antagonists is effective in reducing this effect. Thus ACE isoform shift may represent an important component of the development of cardiac remodeling in response to hemodynamic overload, and its correction may contribute to the beneficial therapeutic effects of renin-angiotensin-aldosterone system inhibitors.

Effects of eplerenone on transcriptional factors and mRNA expression related to cardiac remodelling after myocardial infarction

OBJECTIVE

To examine the effects of eplerenone, a selective aldosterone blocker, on cardiac function after myocardial infarction (MI) and myocardial remodelling related transcriptional factors and mRNA expression in non-infarcted myocardium.

METHODS

MI was induced by ligation of the coronary artery in Wistar rats. Rats were randomly assigned to a vehicle treated group or an eplerenone treated group (100 mg/kg/day).

RESULTS

At four weeks after MI, left ventricular (LV) end diastolic pressure, LV weight, and LV end diastolic dimension were increased in MI rats. Eplerenone significantly reduced the increase in LV end diastolic pressure, LV weight, and LV end diastolic dimension. In the MI rats the decreased ejection fraction indicated systolic dysfunction and the increased E wave to A wave ratio and E deceleration rate indicated diastolic dysfunction. Eplerenone significantly attenuated this systolic and diastolic dysfunction. Myocardial interstitial fibrosis, transcriptional activities of activator protein 1 and nuclear factor kappaB, and mRNA expression of monocyte chemoattractant protein 1, plasminogen activator inhibitor 1, atrial natriuretic peptide, brain natriuretic peptide, and collagen types I and III were significantly increased at four weeks after MI. Eplerenone significantly attenuated interstitial fibrosis and suppressed transcriptional activity and mRNA expression of these genes.

CONCLUSIONS

When administered after MI, eplerenone prevents cardiac remodelling accompanied by systolic and diastolic dysfunction and inhibits abnormal myocardial transcriptional activities and gene expression.

Eplerenone : a review of its use in left ventricular systolic dysfunction and heart failure after acute myocardial infarction

Eplerenone (Inspra) is a selective aldosterone blocker. Oral eplerenone is approved for use in patients with left ventricular (LV) systolic dysfunction and clinical evidence of heart failure following acute myocardial infarction (MI) in the US and in European countries (e.g. the UK and The Netherlands). The addition of eplerenone to standard medical therapy significantly improved mortality and morbidity in patients with LV systolic dysfunction and clinical evidence of heart failure following acute MI in the large, well designed EPHESUS (Eplerenone Post-acute myocardial infarction Heart failure Efficacy and SUrvival Study) trial. The beneficial effects of eplerenone on all-cause mortality and cardiovascular mortality were seen within 30 days of randomisation. Eplerenone was generally well tolerated. Although a higher incidence of hyperkalaemia occurred with eplerenone than with placebo, the incidence of hypokalaemia was significantly lower with eplerenone treatment. Thus, the addition of eplerenone to standard medical therapy is an important new strategy for further improving mortality and morbidity in post-MI patients with LV systolic dysfunction and heart failure.

Eplerenone: a review of its use in essential hypertension

Eplerenone is a selective aldosterone blocker (SAB) approved for the treatment of essential hypertension. Oral eplerenone reduced BP effectively in patients with essential hypertension, both as monotherapy and in combination with other agents. The drug is generally well tolerated; the risk of hyperkalemia can be managed through careful selection and monitoring of patients. Preliminary data suggest that treatment of hypertension with eplerenone may provide protective effects against end-organ disease; further work is needed to elucidate the clinical significance of these findings, and to evaluate the outcome of treatment of hypertension in terms of cardiovascular morbidity and mortality and quality of life. In the meantime, as the first SAB to become available, eplerenone is an interesting addition to the drugs currently available for the treatment of hypertension.

Eplerenone: Selective Aldosterone Antagonism in Management of Cardiovascular and Renal Disease

OBJECTIVE

To review the pharmacology, safety, and efficacy data, as well as therapeutic use of eplerenone (Inspra-Pfizer) for management of cardiovascular and renal disease.

DATA SOURCES

A Medline search (January 1980-July 2003) was performed using eplerenone, aldosterone, aldosterone antagonist, spironolactone, and other pertinent terms. Additional articles were identified from bibliographies of retrieved articles.

STUDY SELECTION

All retrievable studies and review articles discussing the pharmacology, safety, and efficacy of eplerenone were evaluated.

DATA EXTRACTION

By the authors.

DATA SYNTHESIS

The detrimental role of the renin-angiotensin-aldosterone system (RAAS) in the pathophysiology of cardiovascular and renal disease has been well documented. Until recently, however, the direct injurious effects of aldosterone on nonclassical tissues such as the brain, heart, and vasculature have been overlooked. Although angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) significantly reduce morbidity and mortality associated with heart disease, preliminary data suggest further benefit with additional aldosterone blockade. The nonselective aldosterone antagonist spironolactone has demonstrated profound morbidity and mortality benefit in heart failure patients, but since its adverse event profile makes it unattractive to patients with milder disease, the need for a selective aldosterone receptor antagonist is evident. Preclinical studies with eplerenone, a recently approved selective aldosterone receptor antagonist, demonstrate a protective effect on nonclassical tissues, thus reducing injury associated with long-term unopposed aldosterone exposure. Early clinical trials with eplerenone have demonstrated additional benefit in hypertension, heart failure, and nephropathy, although long-term morbidity and mortality outcome data in patients with various levels of disease severity are necessary to define the role of eplerenone in current cardiovascular pharmacotherapy.

CONCLUSION

Eplerenone offers a new selective approach to optimizing aldosterone blockade. The availability of additional morbidity and mortality outcome data in various cardiovascular conditions will provide further insights into its role in clinical practice.

Prevention and Reversal of LV Remodeling with Neurohormonal Inhibitors

Left ventricular (LV) remodeling refers to alterations in ventricular mass, chamber size, and shape that result from myocardial injury, pressure, or volume overload. Numerous studies have demonstrated that LV remodeling correlates with the incidence of heart failure and death, supporting a causative role for remodeling in heart failure progression. Heart failure trials have shown that neurohormonal antagonists, including angiotensin-converting enzyme (ACE) inhibitors and beta-adrenergic receptor blockers (beta blockers), reduce remodeling in parallel with improved clinical outcomes. Existing data favor using angiotensin II type 1 (AT1) receptor antagonists (or "ARBs"), although their anti-remodeling effects are less well established. Recently, mineralocorticoid receptor antagonists have gained substantial interest based on favorable clinical trial results, although data regarding their effects on remodeling are limited. Thus, an optimal medical regimen to prevent or limit LV remodeling in patients with LV dysfunction should include both an ACE inhibitor and beta-adrenergic receptor antagonist, irrespective of the degree of LV dysfunction and symptom status. For patients intolerant to ACE inhibitors, an AT1 receptor antagonist should be substituted. An aldosterone antagonist should be administered to patients with severe, New York Heart Association class III to IV heart failure who have normal or only mildly impaired renal function, or to those patients with depressed LV function following an acute myocardial infarction. Through the aggressive pharmacologic inhibition of both the renin-angiotensin-aldosterone and sympathetic nervous systems, progressive LV remodeling can be prevented or hindered, thereby favorably altering the natural history of the heart failure syndrome.

Evolving role of aldosterone blockers alone and in combination with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers in hypertension management: a review of mechanistic and clinical data

The renin-angiotensin-aldosterone system (RAAS) plays an integral role in blood pressure regulation and has long been a target of pharmacologic approaches to controlling blood pressure. Traditionally, clinical interventions involving the RAAS have focused mainly on inhibiting the action of angiotensin II with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, and limited attention has been devoted to direct inhibition of the action of aldosterone. Recent advances in understanding the role of aldosterone in cardiovascular injury have elevated the importance of direct inhibition of the action of this hormone in the long-term control of blood pressure and have led to the development of the selective aldosterone blocker eplerenone. This article reviews the role of the RAAS in the development of hypertension and discusses the rationale for the use of eplerenone with other medications affecting the RAAS to control blood pressure.

Aldosterone target organ protection by eplerenone

The classical mineralocorticoid effect of aldosterone on unidirectional transepithelial sodium transport in the kidney was long thought to be the predominant effect of this hormone. However, there is convincing evidence for additional extrarenal actions of aldosterone that are mediated via activation of mineralocorticoid receptors (MRs) in the heart, vasculature and brain. It is now postulated that many of the detrimental effects of aldosterone are mediated through MR activation in these nonclassical target organs. The selective aldosterone blocker, eplerenone (Inspra), is under development for human therapeutic use for treatment of hypertension and heart failure post-myocardial infarction (MI). Clinical and preclinical studies have linked elevated aldosterone to hypertension, left ventricular and vascular remodeling, cardiac, renal, and cerebral vascular inflammation and injury, and increased risk of mortality in heart failure patients. Multiple studies in experimental models of hypertension and heart failure demonstrate that selective blockade of aldosterone by eplerenone effectively preserves cardiac function, attenuates maladaptive left ventricular remodeling and tissue and vascular injury in part by reducing vascular inflammation in aldosterone target organs.

The evolution of aldosterone antagonists

Since the isolation and purification of aldosterone from adrenal extracts 50 years ago (Experientia 9 (1953) 33), scientists have learned a great deal about how and where aldosterone acts, the factors that control its release, what is its role in the pathophysiology of cardiovascular disease, how to make and study aldosterone antagonists, and for what medical purposes these agents are useful. In this paper, we will discuss the evolution of aldosterone antagonists from the relatively nonselective spironolactone (Aldactone), to the highly selective eplerenone (Inspra). Eplerenone represents a molecule with improved steroid receptor selectivity and pharmacokinetic properties in man compared to spironolactone. Recent clinical results have demonstrated that these improvements translate into tolerability and efficacy in patients with cardiovascular disease.

Eplerenone: a selective aldosterone blocker

Recent studies suggest that aldosterone may play a larger role than once appreciated in normal physiologic function and cardiovascular disease. Some of the adverse cardiovascular effects that have been described include cardiac and vascular fibrosis, vascular necrosis and inflammation, impaired endothelial function, reduced fibrinolysis, hypertension, left ventricular hypertrophy (LVH), congestive heart failure, and cardiac arrhythmias. In light of these findings, the ability to block the actions of aldosterone has gained increased therapeutic importance. Eplerenone is a selective aldosterone receptor blocker that displays little interaction with androgen and progesterone receptors. Eplerenone has already been approved for the treatment of systemic hypertension and has been evaluated in numerous hypertension subgroups, including patients with low plasma renin activity; diabetes; LVH; uncontrolled blood pressure while receiving monotherapy with angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, calcium channel blockers, or beta-blockers; and in black patients. Results of these trials indicate that eplerenone lowers blood pressure and reduces end-organ damage. Further proof of the therapeutic importance of mineralocorticoid receptor blockade comes from the eplerenone post acute myocardial infarction survival and efficacy study (EPHESUS). In this large-scale clinical outcome trial, eplerenone was shown to reduce total mortality by 15% as well as the combined endpoint of cardiovascular mortality/cardiovascular hospitalization by 13% when administered at a mean of 7.3 days post myocardial infarction to patients with evidence of systolic left ventricular dysfunction and symptoms of heart failure. Eplerenone is well tolerated, with an adverse effect profile comparable to placebo. The advent of selective aldosterone blockers, such as eplerenone, should prove to be of great therapeutic value in hypertension control and prevention of cardiovascular disease and associated end-organ damage.