Modulation of RAAS-natriuretic peptides in the treatment of HF: Old guys and newcomers

Current and future therapeutic perspective in chronic heart failure

The incidence of heart failure is primarily flat or declining for a presumably reflecting better management of cardiovascular diseases, but that of heart failure with preserved ejection fraction (HFpEF) is probably increasing for the lack of an established effective treatment. Moreover, there is no specific pharmacological treatment for patients with heart failure with mildly reduced ejection fraction (HFmrEF) since no substantial prospective randomized clinical trial has been performed exclusively in such population. According to the recent 2021 European Society of Cardiology (ESC) guidelines, the triad composed of an Angiotensin Converting Enzyme inhibitor or Angiotensin Receptor-Neprilysin Inhibitor (ARNI), a beta-blocker, and a Mineralcorticoid Receptor Antagonist is the cornerstone therapy for all patients with heart failure with reduced ejection fraction (HFrEF) but a substantial gap exists for patients with HFpEF/HFmrEF. Despite the important role of the Renin-Angiotensin-Aldosterone System (RAAS) in heart failure pathophysiology, RAAS blockers were found ineffective for HFpEF patients. Indeed, even the new drug class of ARNI was found effective only in HFrEF patients. In this regard, a therapeutic alternative may be represented by drug stimulating the non-classic RAAS (ACE2 and A1-7) as well as other emerging drug classes (such as SGLT2 inhibitors). Reflecting on this global health burden and the gap in treatments among heart failure phenotypes, we summarize the leading players of heart failure pathophysiology, the available pharmacological treatments for each heart failure phenotype, and that in future development.

Angiotensin II and angiotensin 1-7: which is their role in atrial fibrillation?

Atrial fibrillation (AF) is a significant cause of morbidity and mortality as well as a public health burden considering the high costs of AF-related hospitalizations. Pre-clinical and clinical evidence showed a potential role of the renin angiotensin system (RAS) in the etiopathogenesis of AF. Among RAS mediators, angiotensin II (AII) and angiotensin 1-7 (A1-7) have been mostly investigated in AF. Specifically, the stimulation of the pathway mediated by AII or the inhibition of the pathway mediated by A1-7 may participate in inducing and sustaining AF. In this review, we summarize the evidence showing that both RAS pathways may balance the onset of AF through different biological mechanisms involving inflammation, epicardial adipose tissue (EAT) accumulation, and electrical cardiac remodeling. EAT is a predictor for AF as it may induce its onset through direct (infiltration of epicardial adipocytes into the underlying atrial myocardium) and indirect (release of inflammatory adipokines, the stimulation of oxidative stress, macrophage phenotype switching, and AF triggers) mechanisms. Classic RAS blockers such as angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) may prevent AF by affecting the accumulation of the EAT, representing a useful therapeutic strategy for preventing AF especially in patients with heart failure and known left ventricular dysfunction. Further studies are necessary to prove this benefit in patients with other cardiovascular diseases. Finally, the possibility of using the A1-7 or ACE2 analogues, to enlarge current therapeutic options for AF, may represent an important field of research.

Myocardial protective effect of sacubitril-valsartan on rats with acute myocardial infarction

OBJECTIVE

The purpose of this study was to explore the effect of sacubitril-valsartan on rats with acute myocardial infarction.

METHODS

Sprague-dawley rats were randomly divided into six groups. Rats in Group A and B were threaded without deligation and treated with valsartan (34 mg/kg) or sacubitril-valsartan (68 mg/kg) after operation. Rats in Group C and D were given the two drugs (34 mg/kg, 68 mg/kg) after ligation of the left anterior descending branch for 40 minutes. Rats in Group E and F were restored the blood of the coronary artery after ligation, and given the two drugs (34 mg/kg, 68 mg/kg) at the same time. N-terminal pro-brain natriuretic peptide, high sensitivity troponin T, aldosterone and Cyclic guanosine monophosphate were measured and Color Doppler echocardiography was performed. Six weeks later, the rats were killed, the hearts were weighed and stained with Masson staining.

RESULTS

Compared with Group A and B, the levels of N-terminal pro-brain natriuretic peptide, high sensitivity troponin T, aldosterone and Cyclic guanosine monophosphate in other groups were significantly increased (p < 0.05). Before treatment, the left ventricular end diastolic diameter and left ventricular end systolic diameter were similar in each group. After treatment, the levels of left ventricular end diastolic diameter and left ventricular end systolic diameter, and collagen fiber range stained with blue in other groups were significantly increased in comparison with Group A and B (p < 0.05). In addition, the left ventricular volume and collagen fiber range stained with blue were notably decreased, the levels of ejection fraction (EF) were increased in sacubitril-valsartan groups in comparison with valsartan groups (p < 0.05).

CONCLUSION

Early application of sacubitril-valsartan has a protective effect on rats with acute myocardial infarction.

Effects of pretreatment with terazosin and valsartan on intraoperative haemodynamics in patients with phaeochromocytoma

OBJECTIVE

Surgery is the primary strategy for treating phaeochromocytoma (PCC), but it can lead to severe hypertension and heart failure. Although valsartan is effective in reducing high blood pressure, clinical data on the potential role of valsartan in PCC are currently limited. Therefore, the aim of this study was to investigate the effects of pretreatment with terazosin and valsartan on patients with PCC.

METHODS

In this retrospective cohort study, 50 patients who underwent laparoscopic resection of PCC were enrolled. During preoperative preparation, the patients (n=25) in the control group were treated with terazosin, while those (n=25) in the combination treatment group were treated with terazosin and valsartan. The levels of catecholamine hormones before and after surgery were determined, and the intraoperative blood pressure and the incidence of complications were compared between the two groups.

RESULTS

The results showed no significant differences in baseline patient characteristics or surgical conditions between the two groups (p>0.05). However, on the third day after surgery, the levels of catecholamine hormones in the two groups were significantly lower than those before surgery (p<0.05), while the levels in the combination treatment group were notably lower than those in the control group (p<0.05). The patients in the combination treatment group showed lower intraoperative blood pressure fluctuations and incidence of perioperative complications compared with the control group (p<0.05).

CONCLUSIONS

Terazosin combined with valsartan can effectively improve perioperative haemodynamic instability and reduce postoperative complications in the preoperative management of PCC.

Bioelectrical impedance analysis in the management of heart failure in adult patients with congenital heart disease

OBJECTIVE

The recognition of fluid retention is critical in treating heart failure (HF). Bioelectrical impedance analysis (BIA) is a well-known noninvasive method; however, data on its role in managing patients with congenital heart disease (CHD) are limited. Here, we aimed to clarify the correlation between BIA and HF severity as well as the prognostic value of BIA in adult patients with CHD.

DESIGN

This prospective single-center study included 170 patients with CHD admitted between 2013 and 2015. We evaluated BIA parameters (intra- and extracellular water, protein, and mineral levels, edema index [EI, extracellular water-to-total body water ratio]), laboratory values, and HF-related admission prevalence.

RESULTS

Patients with New York Heart Association (NYHA) functional classes III-IV had a higher EI than those with NYHA classes I-II (mean ± SD, 0.398 ± 0.011 vs 0.384 ± 0.017, P < .001). EI was significantly correlated with brain natriuretic peptide level (r = 0.51, P < .001). During the mean follow-up period of 7.1 months, Kaplan-Meier analysis showed that a discharge EI > 0.386, the median value in the present study, was significantly associated with a future increased risk of HF-related admission (HR = 4.15, 95% CI = 1.70－11.58, P < .001). A body weight reduction during hospitalization was also related to EI reduction.

CONCLUSIONS

EI determined using BIA could be a useful marker for HF severity that could predict future HF-related admissions in adult patients with CHD.

Erythropoietin alleviates post-resuscitation myocardial dysfunction in rats potentially through increasing the expression of angiotensin II receptor type 2 in myocardial tissues

Activation of renin-angiotensin system (RAS) is one of the pathological mechanisms associated with myocardial ischemia-reperfusion injury following resuscitation. The present study aimed to determine whether erythropoietin (EPO) improves post‑resuscitation myocardial dysfunction and how it affects the renin‑angiotensin system. Sprague‑Dawley rats were randomly divided into sham, vehicle, epinephrine (EP), EPO and EP + EPO groups. Excluding the sham group, all groups underwent cardiopulmonary resuscitation (CPR) 4 min after asphyxia‑induced cardiac arrest (CA). EP and/or EPO was administrated by intravenous injection when CPR began. The results demonstrated that the vehicle group exhibited lower mean arterial pressure, left ventricular systolic pressure, maximal ascending rate of left ventricular pressure during left ventricular isovolumic contraction and maximal descending rate of left ventricular pressure during left ventricular isovolumic relaxation (+LVdP/dt max and ‑LVdP/dt max, respectively), and higher left ventricular end‑diastolic pressure, compared with the sham group following return of spontaneous circulation (ROSC). Few significant differences were observed concerning the myocardial function between the vehicle and EP groups; however, compared with the vehicle group, EPO reversed myocardial function indices following ROSC, excluding‑LVdP/dt max. Serum renin and angiotensin (Ang) II levels were measured by ELISA. The serum levels of renin and Ang II were significantly increased in the vehicle group compared with the sham group, which was also observed for the myocardial expression of renin and Ang II receptor type 1 (AT1R), as determined by reverse transcription‑quantitative polymerase chain reaction and western blotting. EPO alone did not significantly reduce the high serum levels of renin and Ang II post-resuscitation, but changed the protein levels of renin and AT1R expression in myocardial tissues. However, EPO enhanced the myocardial expression of Ang II receptor type 2 (AT2R) following ROSC. In conclusion, the present study confirmed that CA resuscitation activated the renin‑Ang II‑AT1R signaling pathway, which may contribute to myocardial dysfunction in rats. The present study confirmed that EPO treatment is beneficial for protecting cardiac function post‑resuscitation, and the roles of EPO in alleviating post‑resuscitation myocardial dysfunction may potentially be associated with enhanced myocardial expression of AT2R.

Kallikrein-kinin system as the dominant mechanism to counteract hyperactive renin-angiotensin system

The renin-angiotensin system (RAS) generates, maintains, and makes worse hypertension and cardiovascular diseases (CVDs) through its biologically active component angiotensin II (Ang II), that causes vasoconstriction, sodium retention, and structural alterations of the heart and the arteries. A few endogenous vasodilators, kinins, natriuretic peptides, and possibly angiotensin (1-7), exert opposite actions and may provide useful therapeutic agents. As endothelial autacoids, the kinins are potent vasodilators, active natriuretics, and protectors of the endothelium. Indeed, the kallikrein-kinin system (KKS) is considered the dominant mechanism for counteracting the detrimental effects of the hyperactive RAS. The 2 systems, RAS and KKS, are controlled by the angiotensin-converting enzyme (ACE) that generates Ang II and inactivates the kinins. Inhibitors of ACE can reduce the impact of Ang II and potentiate the kinins, thus contributing to restore the cardiovascular homeostasis. In the last 20 years, ACE-inhibitors (ACE-Is) have become the drugs of first choice for the treatments of the major CVDs. ACE-Is not only reduce blood pressure, as sartans also do, but by protecting and potentiating the kinins, they can reduce morbidity and mortality and improve the quality of life for patients with CVDs. This paper provides a brief review of the literature on this topic.

Role of circulating factors in cardiac aging

Worldwide increase in life expectancy is a major contributor to the epidemic of chronic degenerative diseases. Aging, indeed, simultaneously affects multiple organ systems, and it has been hypothesized that systemic alterations in regulators of tissue physiology may regulate this process. Cardiac aging itself is a major risk factor for cardiovascular diseases and, because of the intimate relationship with the brain, may contribute to increase the risk of neurodegenerative disorders. Blood-borne factors may play a major role in this complex and still elusive process. A number of studies, mainly based on the revival of parabiosis, a surgical technique very popular during the 70s of the 20th century to study the effect of a shared circulation in two animals, have indeed shown the potential that humoral factors can control the aging process in different tissues. In this article we review the role of circulating factors in cardiovascular aging. A better understanding of these mechanisms may provide new insights in the aging process and provide novel therapeutic opportunities for chronic age-related disorders.

New and old roles of the peripheral and brain renin-angiotensin-aldosterone system (RAAS): Focus on cardiovascular and neurological diseases

It is commonly accepted that the renin-angiotensin-aldosterone system (RAAS) is a cardiovascular circulating hormonal system that plays also an important role in the modulation of several patterns in the brain. The pathway of the RAAS can be divided into two classes: the traditional pathway of RAAS, also named classic RAAS, and the non-classic RAAS. Both pathways play a role in both cardiovascular and neurological diseases through a peripheral or central control. In this regard, renewed interest is growing in the last years for the consideration that the brain RAAS could represent a new important therapeutic target to regulate not only the blood pressure via central nervous control, but also neurological diseases. However, the development of compounds able to cross the blood-brain barrier and to act on the brain RAAS is challenging, especially if the metabolic stability and the half-life are taken into consideration. To date, two drug classes (aminopeptidase type A inhibitors and angiotensin IV analogues) acting on the brain RAAS are in development in pre-clinical or clinical stages. In this article, we will present an overview of the biological functions played by peripheral and brain classic and non-classic pathways of the RAAS in several clinical conditions, focusing on the brain RAAS and on the new pharmacological targets of the RAAS.

Monitoring B-type natriuretic peptide in patients undergoing therapy with neprilysin inhibitors. An emerging challenge?

B-type natriuretic peptide (BNP) is primarily synthesized by the ventricles of the heart as a 108-amino acid polypeptide precursor (i.e., proBNP), which is then cleaved into a 76-amino acid biologically inert N-terminal fragment (NT-proBNP) and a biologically active 32-amino acid peptide (BNP). The generation of BNP is considerably enhanced in response to high ventricular filling pressures, so that the measurement of either the active hormone or NT-proBNP has become a mainstay in patients with congestive heart failure. Recent evidence was brought that the enzyme neprilysin efficiently degrades circulating BNP in vivo, whereas proBNP and NT-proBNP are virtually resistant to enzymatic cleavage. Increasing emphasis is currently placed on the fact that that measuring BNP in patients taking the novel and promising neprilysin inhibitors such as LCZ696 may not reliably reflect cardiac dysfunction. Since laboratory monitoring in patients with heart failure should be aimed to define the role of BNP in modulating fluid hemostasis and cardiac remodeling, but natriuretic peptides should also serve as reliable biomarkers of cardiac function and treatment response in these patients, the assessment of neither BNP nor NT-proBNP alone provides a comprehensive biological and clinical picture. Therefore, it seems reasonable to suggest both BNP and the neprilysin-resistant peptide NT-proBNP should be concomitantly assessed in patients with heart failure who take neprilysin inhibitors, so allowing to concomitantly monitor the progression of heart failure and to assess the actual cardiorenal potency of circulating BNP.