Neurohumoral effects of the new orally active renin inhibitor, aliskiren, in chronic heart failure

Mechanisms for the development of heart failure and improvement of cardiac function by angiotensin-converting enzyme inhibitors

Angiotensin-converting enzyme (ACE) inhibitors, which prevent the conversion of angiotensin I to angiotensin II, are well-known for the treatments of cardiovascular diseases, such as heart failure, hypertension and acute coronary syndrome. Several of these inhibitors including captopril, enalapril, ramipril, zofenopril and imidapril attenuate vasoconstriction, cardiac hypertrophy and adverse cardiac remodeling, improve clinical outcomes in patients with cardiac dysfunction and decrease mortality. Extensive experimental and clinical research over the past 35 years has revealed that the beneficial effects of ACE inhibitors in heart failure are associated with full or partial prevention of adverse cardiac remodeling. Since cardiac function is mainly determined by coordinated activities of different subcellular organelles, including sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils, for regulating the intracellular concentration of Ca2+ and myocardial metabolism, there is ample evidence to suggest that adverse cardiac remodelling and cardiac dysfunction in the failing heart are the consequence of subcellular defects. In fact, the improvement of cardiac function by different ACE inhibitors has been demonstrated to be related to the attenuation of abnormalities in subcellular organelles for Ca2+-handling, metabolic alterations, signal transduction defects and gene expression changes in failing cardiomyocytes. Various ACE inhibitors have also been shown to delay the progression of heart failure by reducing the formation of angiotensin II, the development of oxidative stress, the level of inflammatory cytokines and the occurrence of subcellular defects. These observations support the view that ACE inhibitors improve cardiac function in the failing heart by multiple mechanisms including the reduction of oxidative stress, myocardial inflammation and Ca2+-handling abnormalities in cardiomyocytes.

Role of angiotensin II in the development of subcellular remodeling in heart failure

The development of heart failure under various pathological conditions such as myocardial infarction (MI), hypertension and diabetes are accompanied by adverse cardiac remodeling and cardiac dysfunction. Since heart function is mainly determined by coordinated activities of different subcellular organelles including sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils for regulating the intracellular concentration of Ca2+, it has been suggested that the occurrence of heart failure is a consequence of subcellular remodeling, metabolic alterations and Ca2+-handling abnormalities in cardiomyocytes. Because of the elevated plasma levels of angiotensin II (ANG II) due to activation of the renin-angiotensin system (RAS) in heart failure, we have evaluated the effectiveness of treatments with angiotensin converting enzyme (ACE) inhibitors and ANG II type 1 receptor (AT1R) antagonists in different experimental models of heart failure. Attenuation of marked alterations in subcellular activities, protein content and gene expression were associated with improvement in cardiac function in MI-induced heart failure by treatment with enalapril (an ACE inhibitor) or losartan (an AT1R antagonist). Similar beneficial effects of ANG II blockade on subcellular remodeling and cardiac performance were also observed in failing hearts due to pressure overload, volume overload or chronic diabetes. Treatments with enalapril and losartan were seen to reduce the degree of RAS activation as well as the level of oxidative stress in failing hearts. These observations provide evidence which further substantiate to support the view that activation of RAS and high level of plasma ANG II play a critical role in inducing subcellular defects and cardiac dys-function during the progression of heart failure.

Normalizing Plasma Renin Activity in Experimental Dilated Cardiomyopathy: Effects on Edema, Cachexia, and Survival

Heart failure (HF) patients frequently have elevated plasma renin activity. We examined the significance of elevated plasma renin activity in a translationally-relevant model of dilated cardiomyopathy (DCM), which replicates the progressive stages (A–D) of human HF. Female mice with DCM and elevated plasma renin activity concentrations were treated with a direct renin inhibitor (aliskiren) in a randomized, blinded fashion beginning at Stage B HF. By comparison to controls, aliskiren treatment normalized pathologically elevated plasma renin activity (p < 0.001) and neprilysin levels (p < 0.001), but did not significantly alter pathological changes in plasma aldosterone, angiotensin II, atrial natriuretic peptide, or corin levels. Aliskiren improved cardiac systolic function (ejection fraction, p < 0.05; cardiac output, p < 0.01) and significantly reduced the longitudinal development of edema (extracellular water, p < 0.0001), retarding the transition from Stage B to Stage C HF. The normalization of elevated plasma renin activity reduced the loss of body fat and lean mass (cachexia/sarcopenia), p < 0.001) and prolonged survival (p < 0.05). In summary, the normalization of plasma renin activity retards the progression of experimental HF by improving cardiac systolic function, reducing the development of systemic edema, cachexia/sarcopenia, and mortality. These data suggest that targeting pathologically elevated plasma renin activity may be beneficial in appropriately selected HF patients.

Renin Activity in Heart Failure with Reduced Systolic Function-New Insights

Regardless of the cause, symptomatic heart failure (HF) with reduced ejection fraction (rEF) is characterized by pathological activation of the renin–angiotensin–aldosterone system (RAAS) with sodium retention and extracellular fluid expansion (edema). Here, we review the role of active renin, a crucial, upstream enzymatic regulator of the RAAS, as a prognostic and diagnostic plasma biomarker of heart failure with reduced ejection fraction (HFrEF) progression; we also discuss its potential as a pharmacological bio-target in HF therapy. Clinical and experimental studies indicate that plasma renin activity is elevated with symptomatic HFrEF with edema in patients, as well as in companion animals and experimental models of HF. Plasma renin activity levels are also reported to be elevated in patients and animals with rEF before the development of symptomatic HF. Modulation of renin activity in experimental HF significantly reduces edema formation and the progression of systolic dysfunction and improves survival. Thus, specific assessment and targeting of elevated renin activity may enhance diagnostic and therapeutic precision to improve outcomes in appropriate patients with HFrEF.

Efficacy of aliskiren supplementation for heart failure : A meta-analysis of randomized controlled trials

BACKGROUND

Aliskiren might be beneficial for heart failure. However, the results of various studies are controversial. We conducted a systematic review and meta-analysis to explore the efficacy of aliskiren supplementation for heart failure.

METHODS

PubMed, Embase, Web of Science, EBSCO, and the Cochrane Library databases were systematically searched. Randomized controlled trials (RCTs) assessing the efficacy of aliskiren for heart failure were included. Two investigators independently searched for articles, extracted data, and assessed the quality of included studies. The meta-analysis was performed using the random-effect model.

RESULTS

Five RCTs comprising 1973 patients were included in the meta-analysis. Compared with control interventions in heart failure, aliskiren supplementation was found to significantly reduce NT-proBNP levels (standardized mean difference [SMD] = -0.12; 95% CI = -0.21 to -0.03 pg/ml; p = 0.008) and plasma renin activity (SMD = -0.66; 95% CI = -0.89 to -0.44 ng/ml.h; p < 0.00001) while increasing plasma renin concentration (SMD = 0.52; 95% CI = 0.30-0.75 ng/l; p < 0.00001); however, it demonstrated no significant influence on BNP levels (SMD = -0.08; 95% CI = -0.31-0.15 pg/ml; p = 0.49), mortality (RR = 0.97; 95% CI = 0.79-1.20; p = 0.79), aldosterone levels (SMD = -0.09; 95% CI = -0.32-0.14 pmol/l; p = 0.44), adverse events (RR = 3.03; 95% CI = 0.18-49.51; p = 0.44), and serious adverse events (RR = 1.34; 95% CI = 0.54-3.33; p = 0.53).

CONCLUSION

Aliskiren supplementation was found to significantly decrease NT-proBNP levels and plasma renin activity and to improve plasma renin concentration in the setting of heart failure.

Aliskiren for heart failure: a systematic review and meta-analysis of randomized controlled trials

Objective

To systematically review and synthesize the currently available evidence of aliskiren for the treatment of heart failure.

Materials and Methods

We systematically searched the Cochrane, Embase and PubMed databases to identify the randomized controlled trials (RCT) on the effects of aliskiren on heart failure. Data were synthesized with random effects model and presented in forest plot. Publication bias was evaluated with funnel plot. Heterogeneity was evaluated with Begg's test and Egger's test.

Results

Of 124 studies, 6 RCT of 9845 heart failure patients were included for meta-analysis, including 3727 patients receiving aliskiren. Compared with the controls, aliskiren did not significantly reduce the all-cause mortality (1.02 [0.91-1.14], I² = 0%) or cardiovascular mortality (1.02 [0.88-1.17], I² = 7.3%) of heart failure patients. Total adverse events, renal dysfunction, hypotension and hyperkalaemia were not significantly different between the aliskiren group and control group. Begg's test and Egger's test indicated low heterogeneity. Funnel plots indicated low publication bias.

Conclusions

Aliskiren, either used alone or combined with standard medical therapy, does not significantly reduce the all-cause mortality or cardiovascular mortality of heart failure patients. Although aliskiren does not cause statistically higher adverse events, its adverse events may not be neglected.

Review of novel therapeutic targets for improving heart failure treatment based on experimental and clinical studies

Heart failure (HF) is a major public health priority due to its epidemiological transition and the world's aging population. HF is typified by continuous loss of contractile function with reduced, normal, or preserved ejection fraction, elevated vascular resistance, fluid and autonomic imbalance, and ventricular dilatation. Despite considerable advances in the treatment of HF over the past few decades, mortality remains substantial. Pharmacological treatments including β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists have been proven to prolong the survival of patients with HF. However, there are still instances where patients remain symptomatic, despite optimal use of existing therapeutic agents. This understanding that patients with chronic HF progress into advanced stages despite receiving optimal treatment has increased the quest for alternatives, exploring the roles of additional pathways that contribute to the development and progression of HF. Several pharmacological targets associated with pathogenesis of HF have been identified and novel therapies have emerged. In this work, we review recent evidence from proposed mechanisms to the outcomes of experimental and clinical studies of the novel pharmacological agents that have emerged for the treatment of HF.

Aliskiren, Enalapril, or Aliskiren and Enalapril in Heart Failure

BACKGROUND

Among patients with chronic heart failure, angiotensin-converting-enzyme (ACE) inhibitors reduce mortality and hospitalization, but the role of a renin inhibitor in such patients is unknown. We compared the ACE inhibitor enalapril with the renin inhibitor aliskiren (to test superiority or at least noninferiority) and with the combination of the two treatments (to test superiority) in patients with heart failure and a reduced ejection fraction.

METHODS

After a single-blind run-in period, we assigned patients, in a double-blind fashion, to one of three groups: 2336 patients were assigned to receive enalapril at a dose of 5 or 10 mg twice daily, 2340 to receive aliskiren at a dose of 300 mg once daily, and 2340 to receive both treatments (combination therapy). The primary composite outcome was death from cardiovascular causes or hospitalization for heart failure.

RESULTS

After a median follow-up of 36.6 months, the primary outcome occurred in 770 patients (32.9%) in the combination-therapy group and in 808 (34.6%) in the enalapril group (hazard ratio, 0.93; 95% confidence interval [CI], 0.85 to 1.03). The primary outcome occurred in 791 patients (33.8%) in the aliskiren group (hazard ratio vs. enalapril, 0.99; 95% CI, 0.90 to 1.10); the prespecified test for noninferiority was not met. There was a higher risk of hypotensive symptoms in the combination-therapy group than in the enalapril group (13.8% vs. 11.0%, P=0.005), as well as higher risks of an elevated serum creatinine level (4.1% vs. 2.7%, P=0.009) and an elevated potassium level (17.1% vs. 12.5%, P<0.001).

CONCLUSIONS

In patients with chronic heart failure, the addition of aliskiren to enalapril led to more adverse events without an increase in benefit. Noninferiority was not shown for aliskiren as compared with enalapril. (Funded by Novartis; ATMOSPHERE ClinicalTrials.gov number, NCT00853658.).

Effect of additive renin inhibition with aliskiren on renal blood flow in patients with Chronic Heart Failure and Renal Dysfunction (Additive Renin Inhibition with Aliskiren on renal blood flow and Neurohormonal Activation in patients with Chronic Heart Failure and Renal Dysfunction)

AIMS

We examined the effect of the renin inhibitor, aliskiren, on renal blood flow (RBF) in patients with heart failure with reduced ejection fraction (HFREF) and decreased glomerular filtration rate (GFR). Renal blood flow is the main determinant of GFR in HFREF patients. Both reduced GFR and RBF are associated with increased mortality. Aliskiren can provide additional renin-angiotensin-aldosterone system inhibition and increases RBF in healthy individuals.

METHODS AND RESULTS

Patients with left ventricular ejection fraction ≤45% and estimated GFR 30 to 75 mL/min per 1.73 m(2) on optimal medical therapy were randomized 2:1 to receive aliskiren 300 mg once daily or placebo. Renal blood flow and GFR were measured using radioactive-labeled (125)I-iothalamate and (131)I-hippuran at baseline and 26 weeks. After 41 patients were included, the trial was halted based on an interim safety analysis showing futility. Mean age was 68 ± 9 years, 82% male, GFR (49 ± 16 mL/min per 1.73 m(2)), RBF (294 ± 77 mL/min per 1.73 m(2)), and NT-proBNP 999 (435-2040) pg/mL. There was a nonsignificant change in RBF after 26 weeks in the aliskiren group compared with placebo (-7.1 ± 30 vs +14 ± 54 mL/min per 1.73 m(2); P = .16). However, GFR decreased significantly in the aliskiren group compared with placebo (-2.8 ± 6.0 vs +4.4 ± 9.6 mL/min per 1.73 m(2); P = .01) as did filtration fraction (-2.2 ± 3.3 vs +1.1 ± 3.1%; P = .01). There were no significant differences in plasma aldosterone, NT-proBNP, urinary tubular markers, or adverse events. Plasma renin activity was markedly reduced in the aliskiren group versus placebo throughout the treatment phase (P = .007).

CONCLUSIONS

Adding aliskiren on top of optimal HFREF medical therapy did not improve RBF and was associated with a reduction of GFR and filtration fraction.

Modulation of the renin-angiotensin-aldosterone system in heart failure

The renin-angiotensin-aldosterone system (RAAS) is well-established and continues to be pursued as a therapeutic target in the treatment of heart failure, predominantly due to the success of agents that block RAAS in clinical trials of systolic heart failure. The optimal treatment of heart failure patients with preserved ejection fraction (HFpEF), however, remains unclear. Early trials of direct renin inhibitors have suggested that these agents may play a role in HFpEF, but recent clinical trial results have not been encouraging. Preliminary trials of angiotensin-receptor/neprilysin inhibitors look promising. Whether results with these or other drugs will alter current recommendations remains to be seen. In this review, we assess the current understanding of the role of RAAS modulation in heart failure.

Heart failure highlights in 2012-2013

Heart failure has become the cardiovascular epidemic of the century. The European Journal of Heart Failure is dedicated to the advancement of knowledge in the field of heart failure management. In 2012 and 2013, several pioneering scientific discoveries and paradigm-shifting clinical trials have been published. In the current paper, we will discuss the most significant novel insights into the pathophysiology, diagnosis, and treatment of heart failure that were published during this period. All relevant research areas are discussed, including pathophysiology, co-morbidities, arrhythmias, biomarkers, clinical trials, and device therapy, including left ventricular assist devices.

New roles for renin and prorenin in heart failure and cardiorenal crosstalk

The renin-angiotensin-aldosterone-system (RAAS) plays a central role in the pathophysiology of heart failure and cardiorenal interaction. Drugs interfering in the RAAS form the pillars in treatment of heart failure and cardiorenal syndrome. Although RAAS inhibitors improve prognosis, heart failure–associated morbidity and mortality remain high, especially in the presence of kidney disease. The effect of RAAS blockade may be limited due to the loss of an inhibitory feedback of angiotensin II on renin production. The subsequent increase in prorenin and renin may activate several alternative pathways. These include the recently discovered (pro-) renin receptor, angiotensin II escape via chymase and cathepsin, and the formation of various angiotensin subforms upstream from the blockade, including angiotensin 1–7, angiotensin III, and angiotensin IV. Recently, the direct renin inhibitor aliskiren has been proven effective in reducing plasma renin activity (PRA) and appears to provide additional (tissue) RAAS blockade on top of angiotensin-converting enzyme and angiotensin receptor blockers, underscoring the important role of renin, even (or more so) under adequate RAAS blockade. Reducing PRA however occurs at the expense of an increase plasma renin concentration (PRC). PRC may exert direct effects independent of PRA through the recently discovered (pro-) renin receptor. Additional novel possibilities to interfere in the RAAS, for instance using vitamin D receptor activation, as well as the increased knowledge on alternative pathways, have revived the question on how ideal RAAS-guided therapy should be implemented. Renin and prorenin are pivotal since these are at the base of all of these pathways.

Targeting the renin-angiotensin-aldosterone system in heart failure

The renin-angiotensin-aldosterone system is a well-established therapeutic target in the treatment of heart failure (HF). Substantial advances have been made with existing agents--angiotensin-converting enzyme (ACE) inhibitors, angiotensin II-receptor blockers (ARBs), and mineralocorticoid-receptor antagonists (MRAs)--and new data continue to emerge. The indication for the use of MRAs has been broadened to include potentially all patients who have HF with reduced ejection fraction (HFrEF), and ACE inhibitors might have a novel application in patients who are at risk of left ventricular dysfunction (those with aortic valvular disease or pacing-induced heart disease). ARBs have been shown to be a beneficial alternative to ACE inhibitors in HFrEF, but their value when added to ACE inhibitors has been questioned. Upstream, direct renin blockade with aliskiren is being pursued in two large trials of HF, despite the premature halting of a third study. A substantial, unmet need remains in patients who have HF with preserved ejection fraction (HFpEF). New data on spironolactone and LCZ696 (a combined ARB and neprilysin inhibitor) show promise for these patients. Results of the TOPCAT study of spironolactone in patients with HFpEF are awaited, and LCZ696 is now being tested in a large trial in patients with HFrEF.

The neurohormonal network in the RAAS can bend before breaking

The renin-angiotensin-aldosterone system (RAAS) has evolved in humans as one of the main physiological networks by which blood pressure and blood flow to vital organs is maintained. The RAAS has evolved to circumvent life-threatening events such as hemorrhage and starvation. Although short-term activation of this system had been well suited to counteract such catastrophes of early man, excessive chronic activation of the RAAS plays a fundamental role in the development and progression of cardiovascular disease in modern man. The RAAS is an intricate network comprising a number of major organ systems (heart, kidney, and vasculature) and signaling pathways. The main protagonists are renin, angiotensinogen (Ang), angiotensin I (Ang I), angiotensin II (Ang II), and aldosterone (Aldo). The study and delineation of each of these substances has allowed modern medicine to create targets by which cardiovascular disease can be treated. The main modulators that have been synthesized in this respect are angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), mineralocorticoid receptor blockers (MRBs), and direct renin inhibitors (DRIs). Over the past few decades, each of these substances has proven efficacious to varying degrees amongst a number of clinical settings. Additionally, there exists data for and against the use of these agents in combination. The use of these agents in combination poses a larger question conceptually: can excessive pharmacological inhibition of the RAAS lead to patient harm? This perspective will examine the concept of a neurohormonal inhibition ceiling in pertinent experimental and clinical trials.

Novel therapies in acute and chronic heart failure

Despite past advances in the pharmacological management of heart failure, the prognosis of these patients remains poor, and for many, treatment options remain unsatisfactory. Additionally, the treatments and clinical outcomes of patients with acute decompensated heart failure have not changed substantially over the past few decades. Consequently, there is a critical need for new drugs that can improve clinical outcomes. In the setting of acute heart failure, new inotrops such as cardiac myosin activators and new vasodilators such as relaxin have been developed. For chronic heart failure with reduced ejection fraction, there are several new approaches that target multiple pathophysiological mechanism including novel blockers of the renin-angiotensin-aldosterone system (direct renin inhibitors, dual-acting inhibitors of the angiotensin II receptor and neprilysin, aldosterone synthase inhibitors), ryanodine receptor stabilizers, and SERCA activators. Heart failure with preserved ejection fraction represents a substantial therapeutic problem as no therapy has been demonstrated to improve symptoms or outcomes in this condition. Newer treatment strategies target specific structural and functional abnormalities that lead to increased myocardial stiffness. Dicarbonyl-breaking compounds reverse advanced glycation-induced cross-linking of collagen and improve the compliance of aged and/or diabetic myocardium. Modulation of titin-dependent passive tension can be achieved via phosphorylation of a unique sequence on the extensible region of the protein. This review describes the pathophysiological basis, mechanism of action, and available clinical efficacy data of drugs that are currently under development. Finally, new therapies for the treatment of heart failure complications, such as pulmonary hypertension and anemia, are discussed.

Haemodynamic effects of aliskiren in decompensated severe heart failure

Aim: The renin–angiotensin–aldosterone system (RAAS) has dual pathways to angiotensin II production; therefore, multiple blockages may be useful in heart failure. In this study, we evaluated the short-term haemodynamic effects of aliskiren, a direct renin inhibitor, in patients with decompensated severe heart failure who were also taking angiotensin-converting enzyme (ACE) inhibitors.

Materials and methods: A total of 16 patients (14 men, two women, mean age: 60.3 years) were enrolled in the study. The inclusion criteria included hospitalisation due to decompensated heart failure, ACE inhibitor use, and an ejection fraction < 40% (mean: 21.9 ± 6.7%). The exclusion criteria were: creatinine > 2.0 mg/dl, cardiac pacemaker, serum K+ > 5.5 mEq/l, and systolic blood pressure < 70 mmHg. Patients either received 150 mg/d aliskiren for 7 days (aliskiren group, n = 10) or did not receive aliskiren (control group, n = 6). Primary end points were systemic vascular resistance and cardiac index values. Repeated-measures analysis of variance (ANOVA) was used to assess variables before and after intervention. A two-sided p-value < 0.05 was considered statistically significant.

Results: Compared to pre-intervention levels, systemic vascular resistance was reduced by 20.4% in aliskiren patients, but it increased by 2.9% in control patients ( p = 0.038). The cardiac index was not significantly increased by 19.0% in aliskiren patients, but decreased by 8.4% in control patients ( p = 0.127). No differences in the pulmonary capillary or systolic blood pressure values were observed between the groups.

Conclusion: Aliskiren use reduced systemic vascular resistance in patients with decompensated heart failure taking ACE inhibitors.

Prognostic value of renin and prorenin in heart failure patients with decreased kidney function

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) plays a key role in the progression of heart failure (HF) and concomitant kidney dysfunction. Despite the use of RAAS blockade, sustained activation of RAAS has been suggested to link with adverse outcome. We aimed to investigate the prognostic value of active plasma renin concentration (APRC) and prorenin in patients with HF treated with RAAS-blocking agents and its relationship with kidney function parameters.

METHODS

One hundred clinically stable patients with HF, treated with RAAS-blocking agents, were studied. Renal function parameters including effective renal plasma flow and glomerular filtration rate were measured invasively. The combined end point consisted of all-cause mortality, heart transplantation, and admission to hospital for HF.

RESULTS

Mean age was 58 ± 12 years, and 76% were men. Mean left ventricular ejection fraction was 28 ± 9, and median APRC levels were 24.3 ng/mL per hour. Active plasma renin concentration was most strongly associated with mean arterial pressure (r = 0.60, P < .001). In multivariate linear regression analysis, age, mean arterial pressure, angiotensin II concentration, and use of aldosterone antagonists were significantly related with APRC (adjusted R(2) = 0.53). Patients in the highest quartile of APRC had a worse prognosis. In multivariate analysis, APRC remained associated with worse prognosis: HR 2.87 (95% CI 1.14-7.20), P = .025. Prorenin did not show prognostic value. The prognostic value of APRC was strongest in patients with decreased kidney function.

CONCLUSIONS

Our data indicate that APRC is a strong prognostic factor in patients with HF in the presence of RAAS inhibition, especially in patients with kidney dysfunction.

Direct renin inhibitor aliskiren in women with menopausal metabolic syndrome and arterial hypertension

Aim. To study the effectiveness of a direct renin inhibitor, aliskiren, in patients with menopausal metabolic syndrome (MMS), and to assess aliskiren effects on blood pressure (BP), carbohydrate and lipid metabolism parameters, microalbuminuria, and arterial stiffness. Material and methods. The study included 23 women with MMS, to whom aliskiren monotherapy (150-300 mg/d) was administered. At baseline and in the end of the study, anthropometry, carbohydrate and lipid metabolism parameters assessment, 24-hour BP monitoring, and arterial stiffness assessment by volume sphygmography were performed. Results. By the end of the study, most parameters of circadian BP profile significantly decreased. Target levels of systolic and diastolic BP were achieved in 80 % of the patients. There was a significant reduction in postprandial glucose levels. According to the volume sphygmography results, a decrease in arterial stiffness was accompanied by a significant reduction in pulse wave velocity and augmentation index, with normalization of the former parameter. Conclusion. Aliskiren therapy demonstrated not only high antihypertensive effectiveness in MMS patients, but also a reduction in postprandial glucose levels and arterial stiffness.

Combination angiotensin converting enzyme and direct renin inhibition in heart failure following experimental myocardial infarction

AIMS

Diminishing the activity of the renin-angiotensin system (RAS) plays a pivotal role in the treatment of heart failure. In addition to angiotensin converting enzyme (ACE) inhibitors and angiotensin-receptor blockers, direct renin inhibition has emerged as a potential adjunctive treatment to conventional RAS blockade. We sought to determine the effectiveness of this strategy after myocardial infarction (MI) in the setting of preexisting hypertension, a common premorbid condition in patients with ischemic heart disease.

METHODS AND RESULTS

Ten-week-old female heterozygous hypertensive (mRen-2)27 transgenic rats (Ren-2), were randomized to one of five groups (n = 8 per group); sham, MI, MI + aliskiren, MI + lisinopril and MI + combination lisinopril and aliskiren. Cardiac function was assessed by echocardiography and in vivo cardiac catheterization. Untreated MI animals developed heart failure with hypotension, dilation, reduced ejection fraction (EF), and raised left ventricular end-diastolic pressure (LVEDP). Treatment with single agent treatment had only modest effect on cardiac function though combination therapy was associated with significant improvements in EF and LVEDP when compared to untreated MI animals (P < 0.05). Histologic analysis demonstrated increase extracellular matrix deposition and cardiomyocyte hypertrophy in the noninfarct region of all MI groups when compared with sham operated animals (P < 0.05) that was reduced by ACE inhibitor monotherapy and combination treatment but not by aliskiren alone.

CONCLUSION

In a hypertensive rat model that underwent experimental MI, EF, and LVEDP, key functional indices of heart failure, were improved by treatment with combination ACE and direct renin inhibition when compared with either agent used alone.

Renin inhibitors in chronic heart failure: the Aliskiren Observation of Heart Failure Treatment study in context

Renin-angiotensin aldosterone system (RAAS) activation is a key neurohormonal contributor to the progression of chronic heart failure. Strategies that block this activation have consistently demonstrated major beneficial impacts on morbidity and mortality in this setting. Direct renin inhibitors (DRIs) present a novel opportunity to block at an additional or alternative step in this pathway, that being conversion of angiotensinogen to angiotensin I. Theoretical benefits of blocking at the level of renin include: inhibition of the reflex activation of plasma renin activity induced by conventional downstream RAAS blockers. Minimization of angiotensin II and/or aldosterone escape and blocking upstream at the rate-limiting step of angiotensin I production. Preclinical and early-phase clinical studies have largely supported this hypothesis. In the Aliskiren Observation of Heart Failure Treatment study, patients with systolic chronic heart failure receiving background angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers and β-blockers benefited from aliskiren in reduction vs placebo of plasma levels of brain natriuretic peptide, the primary efficacy endpoint of that study. Large-scale outcome trials are, however, required to definitively determine the benefits of a DRI strategy additional to, or as an alternative to, conventional approaches such as ACE inhibitors in the systolic chronic heart failure setting. Copyright © 2010 Wiley Periodicals, Inc.The authors have no funding, financial relationships, or conflicts of interest to disclose.

Direct renin inhibition: update on clinical investigations with aliskiren

The renin–angiotensin–aldosterone system (RAAS) plays a pivotal role in regulating blood pressure, volume, and electrolytes. The final product of RAAS cascade is angiotensin II, which exerts diverse biological activities via binding to one of three known receptor types, with different binding consequences. Despite the success with conventional strategies to limit angiotensin II production and action, these agents promote a reflex rise in plasma renin activity, which is thought to be associated with an increased incidence of cardiovascular events. Several renin inhibitors have been synthesized in order to counteract deleterious consequences of renin activity and RAAS activation; aliskiren is the first of these new non-peptide direct renin inhibitors to be approved for the treatment of hypertension. The paper reviews pharmacokinetics of aliskiren and its role in hypertension, with particular regard to those studies that compared clinical efficacy of aliskiren in comparison and in addition to other antihypertensive drug strategies.

How should we manage heart failure developing in patients already treated with angiotensin-converting enzyme inhibitors and beta-blockers for hypertension, diabetes or coronary disease?

An increasing number of patients in the community are being treated with angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and beta-blockers for hypertension, coronary disease or diabetic renal and vascular complications. Some of these patients will develop heart failure despite such treatment. Based on data from hypertension trials it can be estimated that approximately 5% of treated patients will develop heart failure over 5 years. It is unclear whether patients developing heart failure on and off ACE-inhibitors or beta-blockers, respectively, at the time of heart failure diagnosis have similar prognosis.Treatment options for patients developing heart failure while already treated with ACE inhibitors/ARBs and beta-blockers are very limited if current heart failure guidelines are followed. In this review possible strategies are outlined and important areas for research are identified. It is suggested that trials are designed specifically to address prognosis and treatment in this growing population.

New class of agents for treatment of hypertension: focus on direct renin inhibition

Aliskiren, the first orally active direct renin inhibitor, is an effective antihypertensive drug with distinctive characteristics, including good blockade of the renin-angiotensin system, a prolonged duration of action, pharmacologic effects that persist after drug discontinuation, and favorable tolerability comparable with placebo. The blood pressure-lowering effect of aliskiren monotherapy is similar, if not superior, to that of other first-line antihypertensive agents, and is greatly enhanced when aliskiren is combined with various other antihypertensive medications, without any adverse drug interactions. Aliskiren is also an effective and well tolerated therapy in special populations, including diabetic, obese, and elderly hypertensives. Beyond its blood pressure-lowering efficacy, results from experimental and clinical trials suggest that aliskiren has positive effects on markers of cardiovascular and renal damage. The ASPIRE (Aliskiren Study in Post-MI patients to Reduce rEmodelling) HIGHER clinical trials program is further assessing whether the promising pharmacologic properties of aliskiren translate into reduced risk of adverse cardiovascular and renal outcomes.

Renal and cardio-protective effects of direct renin inhibition: a systematic literature review

BACKGROUND

Blockade of the renin-angiotensin-aldosterone system (RAAS) at its rate-limiting step by means of renin inhibition has led to the development of direct renin inhibitors (DRIs). Given the renal and cardioprotective effects of RAAS blockade by angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, DRIs may increase the armamentarium for further organ protection. Over the last two decades the effects of DRIs on biomarkers for renal and cardiovascular disease have been investigated. This systematic review aims to delineate the effects of DRIs on surrogate markers of renal and cardiovascular function.

METHODS

MEDLINE and previous systematic reviews were searched for articles reported between 1980 and 2008. A standardized dataset was extracted from articles describing the effects of DRIs on markers of renal and cardiac damage and hard outcomes.

RESULTS

Fifty-two articles were included. Blood pressure reductions were generally insufficient using early generation DRIs. However, recent DRIs have greater blood pressure-lowering effects. Preclinical and clinical studies showed profound effects of DRIs on markers of renal function, including clear increases in renal plasma flow and reductions in albuminuria. These effects were observed either alone or in combination with other RAAS inhibitors and suggest potential large renal protective benefit. DRIs improved hemodynamic cardiovascular parameters, such as total peripheral resistance, arterial pressure and left ventricular mass index, to a similar extent as those observed with other RAAS inhibitors. Furthermore, addition of DRIs to optimal heart failure treatment resulted in further reductions in B-type natriuretic peptide.

CONCLUSIONS

Evidence from preclinical and clinical studies suggests that DRIs may have renal and cardiovascular effects beyond their ability to lower blood pressure. Results of ongoing hard outcome trials are awaited to definitively assess the renal and cardio-protective effects of these agents.

Aliskiren, the first approved renin inhibitor: Clinical application and safety in the treatment of hypertension

Hypertension is one of the most important risk factors for, and causes of, cardiovascular disease. The difficulty in achieving a normal blood pressure range in some patients makes the rate of cardiovascular disease high. For some years renin-angiotensin system inhibitors such as angiotensin-converting enzyme (ACE) and angiotensin receptor blockade have been objects of interest for treatment of cardiovascular disease. Aliskiren, the first approved renin inhibitor to reach the market, is a low molecular weight, orally active, hydrophilic nonpeptide molecule, which blocks angiotensin I generation. However it might also become a reasonable therapeutic choice in a broad number of clinical conditions, as stable coronary artery disease, cerebrovascular and cardiorenal disease, diabetes, and peripheral arterial disease. The aim of this review is to describe the effectiveness and safety of aliskerin in the treatment of hypertension.

The biochemical pharmacology of renin inhibitors: implications for translational medicine in hypertension, diabetic nephropathy and heart failure: expectations and reality

The renin-angiotensin-aldosterone system (RAAS) plays a dominant role in the pathophysiology of hypertension, Diabetes mellitus (DM), chronic kidney disease (CKD) and chronic heart failure (CHF). Therefore, drugs that block key components of the RAAS such as ACE inhibitors (ACEi) and angiotensin receptor blockers (ARBs) have gained wide clinical use for these indications. Despite progress, the morbidity and mortality of patients treated with ACEi or ARBs remain high. Small molecules that directly inhibit renin (DRI) and are orally active have also been developed and one such drug, aliskiren, was introduced into clinical use for treatment of hypertension in 2007. Further clinical trials aimed to expand the therapeutic use of aliskiren are in progress for CKD-DM and CHF. In this review we analyze and review the translational medicine prospects of aliskiren in respect to the biochemical pharmacology of the RAAS, the marketed RAAS modulators and the new emerging science regarding the role of prorenin, renin and renin receptors in cardiovascular biology and disease. The information already gained with aliskiren, raises questions regarding the advantages of DRIs as monotherapy compared to marketed ACEis and ARBs, their potential added value in combination with other RAAS modulators and other unproven benefits in relation to prorenin and renin receptor biology. This review will also indicate basic and clinical research needs that are critical to determine whether DRIs can provide meaningful added medical benefits over contemporary medicines that regulate the RAAS, and the need to identify patients that are more likely to benefit from DRIs and any possible long term adverse effects.

Aliskiren: a novel renoprotective agent or simply an alternative to ACE inhibitors?

Chronic kidney disease (CKD) is a common condition that is increasing in prevalence in developed nations. The economic and psychosocial costs of CKD are considerable, and are associated with high levels of morbidity and mortality. Specific treatments do not exist for many causes of CKD. Therefore, treatment is reliant on the introduction of therapies that retard progression of structural renal damage and renal impairment. At present, aside from judicious use of antihypertensive agents to lower blood pressure, and possibly low-protein diets and statin therapy, blockade of the renin-angiotensin-aldosterone system (RAAS) with angiotensin-converting enzyme inhibitors (ACEis) and angiotensin II receptor blockers (ARBs) are the only widely available treatments. Although these measures attenuate the inexorable progression to renal failure, they do not halt it. One limiting factor may be feedback effects of ACEis and ARBs, such as increased plasma renin activity. Aliskiren is a newer agent that inhibits renin, the rate-limiting step in the RAAS. There are several theoretical reasons to suggest that aliskiren may have renoprotective actions superior to those of ACEis and ARBs. In this paper the available evidence regarding renoprotective effects of aliskiren is reviewed, with an emphasis on comparison with ACEis and ARBs.

The role of renin-angiotensin-aldosterone system-based therapy in diabetes prevention and cardiovascular and renal protection

Hypertension increases the risk of type 2 diabetes mellitus (T2DM) and cardiovascular disease. In addition to lowering blood pressure, blockade of the renin-angiotensin-aldosterone system (RAAS) reduces the risk of new-onset T2DM and offers renal protection. Using a MEDLINE search, we identified multiple trials that reported the incidence of T2DM in patients taking inhibitors of RAAS. In this review, we will discuss the RAAS as a potential target in diabetes prevention and the mechanisms through which inhibitors of this system achieve such an important effect. We will also shed light on the beneficial cardiovascular and renal effects of RAAS blockade. Although multiple studies have demonstrated that inhibitors of RAAS, especially angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, can reduce the incidence of T2DM, randomized controlled studies are still needed to further elucidate their exact role in diabetes prevention.