Are Myocardial Fibrosis and Diastolic Dysfunction Reversible in Hypertensive Heart Disease?

Imaging of Cardiac Fibrosis: An Update, From the AJR Special Series on Imaging of Fibrosis

Myocardial fibrosis (MF) is defined as excessive production and deposition of extra-cellular matrix proteins that result in pathologic myocardial remodeling. Three types of MF have been identified: replacement fibrosis from tissue necrosis, reactive fibrosis from myocardial stress, and infiltrative interstitial fibrosis from progressive deposition of nondegradable material such as amyloid. Although echocardiography, nuclear medicine, and CT play important roles in the assessment of MF, MRI is pivotal in the evaluation of MF, with the late gadolinium enhancement (LGE) technique used as a primary end point. The LGE technique focuses on the pattern and distribution of gadolinium accumulation in the myocardium and assists in the diagnosis and establishment of the cause of both ischemic and nonischemic cardiomyopathy. LGE MRI also aids prognostication and risk stratification. In addition, LGE MRI is used to guide the management of patients considered for ablation for arrhythmias. Parametric mapping techniques, including T1 mapping and extracellular volume measurement, allow detection and quantification of diffuse fibrosis, which may not be detected by LGE MRI. These techniques also allow monitoring of disease progression and therapy response. This review provides an update on the imaging of MF, including prognostication and risk stratification tools, electrophysiologic considerations, and disease monitoring.

Genomic, Proteomic, and Metabolic Comparisons of Small Animal Models of Heart Failure With Preserved Ejection Fraction: A Tale of Mice, Rats, and Cats

Heart failure with preserved ejection fraction (HFpEF) remains a medical anomaly that baffles researchers and physicians alike. The overall phenotypical changes of diastolic function and left ventricular hypertrophy observed in HFpEF are definable; however, the metabolic and molecular alterations that ultimately produce these changes are not well established. Comorbidities such as obesity, hypertension, and diabetes, as well as general aging, play crucial roles in its development and progression. Various animal models have recently been developed to better understand the pathophysiological and metabolic developments in HFpEF and to illuminate novel avenues for pharmacotherapy. These models include multi‐hit rodents and feline aortic constriction animals. Recently, genomic, proteomic, and metabolomic approaches have been used to define altered signaling pathways in the heart associated with HFpEF, including those involved in inflammation, cGMP‐related, Ca²⁺ handling, mitochondrial respiration, and the unfolded protein response in endoplasmic reticulum stress. This article aims to present an overview of what has been learnt by these studies, focusing mainly on the findings in common while highlighting unresolved issues. The knowledge gained from these research models will not simply be of benefit for treating HFpEF but will undoubtedly provide new insights into the mechanisms by which the heart deals with external stresses and how the processes involved can fail.

Reversal of right ventricular pressure loading improves biventricular function independent of fibrosis in a rabbit model of pulmonary artery banding

Right ventricular (RV) pressure loading leads to RV and left ventricular (LV) dysfunction through RV hypertrophy, dilatation and fibrosis. Relief of RV pressure load improves RV function. However, the impact and mechanisms on biventricular reverse-remodelling and function are only partially characterized. We evaluated the impact of RV pressure overload relief on biventricular remodelling and function in a rabbit model of reversible pulmonary artery banding (PAB). Rabbits were randomized to three groups: (1) Sham-operated controls (n = 7); (2) PAB (NDef, n = 7); (3) PAB followed by band deflation (Def, n = 5). Sham and NDef animals were sacrificed at 6 weeks after PAB surgery. Def animals underwent PAB deflation at 6 weeks and sacrifice at 9 weeks. Biventricular geometry, function, haemodynamics, hypertrophy and fibrosis were compared between groups using echocardiography, magnetic resonance imaging, high-fidelity pressure-tipped catheters and histology. RV pressure loading caused RV dilatation, systolic dysfunction, myocyte hypertrophy and LV compression which improved after PAB deflation. RV end-diastolic pressure (RVEDP) decreased after PAB deflation, although remaining elevated vs. Sham. LV end-diastolic pressure (LVEDP) was unchanged following PAB deflation. RV and LV collagen volumes in the NDef and Def group were increased vs. Sham, whereas RV and LV collagen volumes were similar between NDef and Def groups. RV myocyte hypertrophy (r = 0.75, P < 0.001) but not collagen volume was related to RVEDP. LV myocyte hypertrophy (r = 0.58, P = 0.016) and collagen volume (r = 0.56, P = 0.031) correlated with LVEDP. In conclusion, relief of RV pressure overload improves RV and LV geometry, hypertrophy and function independent of fibrosis. The long-term implications of persistent fibrosis and increased biventricular filling pressures, even after pressure load relief, need further study. KEY POINTS: Right ventricular (RV) pressure loading in a pulmonary artery banding rabbit model is associated with RV dilatation, left ventricular (LV) compression; biventricular myocyte hypertrophy, fibrosis and dysfunction. The mechanisms and impact of RV pressure load relief on biventricular remodelling and function has not been extensively studied. Relief of RV pressure overload improves biventricular geometry in conjunction with improved RV myocyte hypertrophy and function independent of reduced fibrosis. These findings raise questions as to the importance of fibrosis as a therapeutic target.

[Extracorporeal membrane oxygenation and hemodynamics : Therapy is not only a friend of the heart]

Extracorporeal support systems for the heart and lungs are employed for cardiac, pulmonary and also cardiopulmonary failure; however, neither the pure lung support by venovenous extracorporeal membrane oxygenation (vvECMO) nor the venoarterial (va) ECMO behave in a hemodynamically inert manner with respect to the patient's own cardiovascular system. The success of ECMO treatment is decisively dependent on monitoring before and during the execution and the pathophysiological understanding of the hemodynamic changes that occur during treatment. This article explicitly elucidates these "concomitant phenomena" and discusses fundamental aspects of cardiovascular physiology and the specific interplay with ECMO treatment.

Imaging tools for assessment of myocardial fibrosis in humans: the need for greater detail

Myocardial fibrosis is recognized as a key pathological process in the development of cardiac disease and a target for future therapeutics. Despite this recognition, the assessment of fibrosis is not a part of routine clinical practice. This is primarily due to the difficulties in obtaining an accurate assessment of fibrosis non-invasively. Moreover, there is a clear discrepancy between the understandings of myocardial fibrosis clinically where fibrosis is predominately studied with comparatively low-resolution medical imaging technologies like MRI compared with the basic science laboratories where fibrosis can be visualized invasively with high resolution using molecularly specific fluorescence microscopes at the microscopic and nanoscopic scales. In this article, we will first review current medical imaging technologies for assessing fibrosis including echo and MRI. We will then highlight the need for greater microscopic and nanoscopic analysis of human tissue and how this can be addressed through greater utilization of human tissue available through endomyocardial biopsies and cardiac surgeries. We will then describe the relatively new field of molecular imaging that promises to translate research findings to the clinical practice by non-invasively monitoring the molecular signature of fibrosis in patients.

Ca2+ Signaling in Cardiac Fibroblasts and Fibrosis-Associated Heart Diseases

Cardiac fibrosis is the excessive deposition of extracellular matrix proteins by cardiac fibroblasts and myofibroblasts, and is a hallmark feature of most heart diseases, including arrhythmia, hypertrophy, and heart failure. This maladaptive process occurs in response to a variety of stimuli, including myocardial injury, inflammation, and mechanical overload. There are multiple signaling pathways and various cell types that influence the fibrogenesis cascade. Fibroblasts and myofibroblasts are central effectors. Although it is clear that Ca2+ signaling plays a vital role in this pathological process, what contributes to Ca2+ signaling in fibroblasts and myofibroblasts is still not wholly understood, chiefly because of the large and diverse number of receptors, transporters, and ion channels that influence intracellular Ca2+ signaling. Intracellular Ca2+ signals are generated by Ca2+ release from intracellular Ca2+ stores and by Ca2+ entry through a multitude of Ca2+-permeable ion channels in the plasma membrane. Over the past decade, the transient receptor potential (TRP) channels have emerged as one of the most important families of ion channels mediating Ca2+ signaling in cardiac fibroblasts. TRP channels are a superfamily of non-voltage-gated, Ca2+-permeable non-selective cation channels. Their ability to respond to various stimulating cues makes TRP channels effective sensors of the many different pathophysiological events that stimulate cardiac fibrogenesis. This review focuses on the mechanisms of Ca2+ signaling in fibroblast differentiation and fibrosis-associated heart diseases and will highlight recent advances in the understanding of the roles that TRP and other Ca2+-permeable channels play in cardiac fibrosis.

Recent Advances in Imaging of Hypertensive Heart Disease

PURPOSE OF REVIEW

To review recent advances in the imaging of hypertensive heart disease (HHD) with an emphasis on developments in the imaging of diffuse myocardial fibrosis using cardiac magnetic resonance (CMR).

RECENT FINDINGS

HHD results from long-standing hypertension and is characterized by the development of left ventricular hypertrophy and diffuse interstitial fibrosis. Diffuse fibrosis traditionally required endomyocardial biopsy to diagnose, but recent developments using T1 mapping in CMR allow for noninvasive assessment. Studies using T1 mapping have shown an increase in extracellular volume fraction (ECV) in patients with HHD compared to normal controls, suggesting ECV can be used as a noninvasive marker for fibrosis in HHD. In addition to T1 mapping, other recent advances in HHD imaging include improvements in three-dimensional echocardiography, allowing for accurate real-time volumetric measurements, and the use of speckle tracking echocardiography to detect subclinical systolic dysfunction. Measurement of ECV using T1 mapping in CMR can be used as a noninvasive marker of diffuse myocardial fibrosis in HHD. While further studies are needed to validate this approach with larger patient cohorts, ECV can potentially be used to both monitor disease progression and assess therapeutic interventions in HHD.

Leukocytic Toll-Like Receptor 2 Deficiency Preserves Cardiac Function And Reduces Fibrosis In Sustained Pressure Overload

An involement of Toll-like receptor 2 (TLR2) has been established in cardiac dysfunction after acute myocardial infarction; however, its role in chronic pressure overload is unclear. We sought to evaluate the role of TLR2 in cardiac hypertrophy, fibrosis and dysfunction in sustained pressure overload. We induced pressure overload via transverse aortic constriction (TAC) in TLR2^−/− and wild type (WT) mice, and followed temporal changes over 8 weeks. Despite similar increases in heart weight, left ventricular (LV) ejection fraction (EF) and diastolic function (mitral E/A ratio) were preserved in TLR2^−/− mice but impaired in WT mice following TAC. TAC produced less LV fibrosis in TLR2^−/− mice associated with lower mRNA levels of collagen genes (Col1a1 and Col3a1) and lower protein level of TGFbeta1, compared to WT mice. Following TAC, the influx of macrophages and CD3 T cells into LV was similar between TLR2^−/− and WT mice, whereas levels of cyto/chemokines were lower in the heart and plasma in TLR2^−/− mice. TLR2^−/− bone marrow-derived cells protected against LVEF decline and fibrosis following TAC. Our findings show that leukocytic TLR2 deficiency protects against LV dysfunction and fibrosis probably via a reduction in inflammatory signaling in sustained pressure overload.

Sexual dimorphism in the fetal cardiac response to maternal nutrient restriction

Poor maternal nutrition causes intrauterine growth restriction (IUGR); however, its effects on fetal cardiac development are unclear. We have developed a baboon model of moderate maternal undernutrition, leading to IUGR. We hypothesized that the IUGR affects fetal cardiac structure and metabolism. Six control pregnant baboons ate ad-libitum (CTRL)) or 70% CTRL from 0.16 of gestation (G). Fetuses were euthanized at C-section at 0.9G under general anesthesia. Male but not female IUGR fetuses showed left ventricular fibrosis inversely correlated with birth weight. Expression of extracellular matrix protein TSP-1 was increased (p<0.05) in male IUGR. Expression of cardiac fibrotic markers TGFβ, SMAD3 and ALK-1 were downregulated in male IUGRs with no difference in females. Autophagy was present in male IUGR evidenced by upregulation of ATG7 expression and lipidation LC3B. Global miRNA expression profiling revealed 56 annotated and novel cardiac miRNAs exclusively dysregulated in female IUGR, and 38 cardiac miRNAs were exclusively dysregulated in males (p<0.05). Fifteen (CTRL) and 23 (IUGR) miRNAs, were differentially expressed between males and females (p<0.05) suggesting sexual dimorphism, which can be at least partially explained by differential expression of upstream transcription factors (e.g. HNF4α, and NFκB p50). Lipidomics analysis of fetal cardiac tissue exhibited a net increase in diacylglycerol and plasmalogens and a decrease in triglycerides and phosphatidylcholines. In summary, IUGR resulting from decreased maternal nutrition is associated with sex-dependent dysregulations in cardiac structure, miRNA expression, and lipid metabolism. If these changes persist postnatally, they may program offspring for higher later life cardiac risk.

A state of reversible compensated ventricular dysfunction precedes pathological remodelling in response to cardiomyocyte-specific activity of angiotensin II type-1 receptor in mice

Cardiac dysfunction is commonly associated with high-blood-pressure-induced cardiomyocyte hypertrophy, in response to aberrant renin-angiotensin system (RAS) activity. Ensuing pathological remodelling promotes cardiomyocyte death and cardiac fibroblast activation, leading to cardiac fibrosis. The initiating cellular mechanisms that underlie this progressive disease are poorly understood. We previously reported a conditional mouse model in which a human angiotensin II type-I receptor transgene (HART) was expressed in differentiated cardiomyocytes after they had fully matured, but not during development. Twelve-month-old HART mice exhibited ventricular dysfunction and cardiomyocyte hypertrophy with interstitial fibrosis following full receptor stimulation, without affecting blood pressure. Here, we show that chronic HART activity in young adult mice causes ventricular dysfunction without hypertrophy, fibrosis or cardiomyocyte death. Dysfunction correlated with reduced expression of pro-hypertrophy markers and increased expression of pro-angiogenic markers in the cardiomyocytes experiencing increased receptor load. This stimulates responsive changes in closely associated non-myocyte cells, including the downregulation of pro-angiogenic genes, a dampened inflammatory response and upregulation of Tgfβ. Importantly, this state of compensated dysfunction was reversible. Furthermore, increased stimulation of the receptors on the cardiomyocytes caused a switch in the secondary response from the non-myocyte cells. Progressive cardiac remodelling was stimulated through hypertrophy and death of individual cardiomyocytes, with infiltration, proliferation and activation of fibroblast and inflammatory cells, leading to increased angiogenic and inflammatory signalling. Together, these data demonstrate that a state of pre-hypertrophic compensated dysfunction can exist in affected individuals before common markers of heart disease are detectable. The data also suggest that there is an initial response from the housekeeping cells of the heart to signals emanating from distressed neighbouring cardiomyocytes to suppress those changes most commonly associated with progressive heart disease. We suggest that the reversible nature of this state of compensated dysfunction presents an ideal window of opportunity for personalised therapeutic intervention.

Highlighted Article: A novel conditional mouse model was used to investigate early initiating stages of heart disease that are commonly overlooked, and identifies a ‘window of opportunity’ for personalised therapeutic intervention.

Ibuprofen attenuates cardiac fibrosis in streptozotocin-induced diabetic rats

OBJECTIVE

To investigate the effects of ibuprofen on cardiac fibrosis in a rat model of type 1 diabetes.

METHODS

The diabetic model was established by injecting streptozotocin into the rats. Then, ibuprofen or pioglitazone was given by gavage for 8 weeks. The cardiac fibrosis was assessed, and the major components of the renin-angiotensin system, the transforming growth factor β1 (TGF-β1) and the mammalian target of rapamycin (mTOR), were evaluated by histopathological, immunohistochemical, Western blot analysis or ELISA assay.

RESULTS

Obvious cardiac fibrosis was detected in the diabetic group and was alleviated by ibuprofen treatment. Angiotensin-converting enzyme (ACE), angiotensin (Ang) II and AngII type 1 receptor (AT1-R) levels were higher, and ACE2, Ang(1-7) and Mas receptor (Mas-R) were lower in the diabetic group. The ratio of ACE to ACE2 was raised in the diabetic group. All these changes were ameliorated by ibuprofen. TGF-β1 and mTOR were raised in the hearts of the diabetic group and were attenuated by ibuprofen treatment. There was no significant difference between the ibuprofen and the pioglitazone groups.

CONCLUSION

Ibuprofen could ameliorate the cardiac fibrosis in diabetic rats by reduction of the ACE/AngII/AT1-R axis and enhancement of the ACE2/Ang(1-7)/Mas-R axis, leading to a decrease in TGF-β1 and mTOR.

Sirtuin-6 inhibits cardiac fibroblasts differentiation into myofibroblasts via inactivation of nuclear factor κB signaling

Differentiation of cardiac fibroblasts (CFs) into myofibroblasts represents a key event in cardiac fibrosis that contributes to pathologic cardiac remodeling. However, regulation of this phenotypic transformation remains elusive. Here, we show that sirtuin-6 (SIRT6), a member of the sirtuin family of nicotinamide adenine dinucleotide-dependent histone deacetylase, plays a role in the regulation of myofibroblast differentiation. SIRT6 expression was upregulated under pathologic conditions in angiotensin II (Ang II)-stimulated CFs and in myocardium of rat subjected to abdominal aortic constriction surgery. SIRT6 depletion by RNA interference (small interfering RNA [siRNA]) in CFs resulted in increased cell proliferation and extracellular matrix deposition. Further examination of SIRT6-depleted CFs demonstrated significantly higher expression of α-smooth muscle actin (α-SMA), the classical marker of myofibroblast differentiation, and increased formation of focal adhesions. Notably, SIRT6 depletion further exacerbated Ang II-induced myofibroblast differentiation. Overexpression of SIRT6 restored α-SMA expression in SIRT6-depleted or Ang II-treated CFs. Moreover, SIRT6 depletion induced the DNA binding activity and transcriptional activity of nuclear factor κB (NF-κB). Importantly, using an NF-κB p65 siRNA or pyrrolidine dithiocarbamate, a specific inhibitor of NF-κB activity, reversed the expression of phenotypic markers of myofibroblasts. Our findings unravel a novel role of SIRT6 as a key modulator in the phenotypic conversion of CFs to myofibroblasts.

The role of PPARδ signaling in the cardiovascular system

Peroxisome proliferator-activated receptors (PPARα, β/δ, and γ), members of the nuclear receptor transcription factor superfamily, play important roles in the regulation of metabolism, inflammation, and cell differentiation. All three PPAR subtypes are expressed in the cardiovascular system with various expression patterns. Among the three PPAR subtypes, PPARδ is the least studied but has arisen as a potential therapeutic target for cardiovascular and many other diseases. It is known that PPARδ is ubiquitously expressed and abundantly expressed in cardiomyocytes. Accumulated evidence illustrates the role of PPARδ in regulating cardiovascular function and determining pathological progression. In this chapter, we will discuss the current knowledge in the role of PPARδ in the cardiovascular system, the mechanistic insights, and the potential therapeutic utilization for treating cardiovascular disease.

PPARδ activity in cardiovascular diseases: A potential pharmacological target

Activation of peroxisome proliferator-activated receptors (PPARs), and particularly of PPARα and PPARγ, using selective agonists, is currently used in the treatment of metabolic diseases such as hypertriglyceridemia and type 2 diabetes mellitus. PPARα and PPARγ anti-inflammatory, antiproliferative and antiangiogenic properties in cardiovascular cells were extensively clarified in a variety of in vitro and in vivo models. In contrast, the role of PPARδ in cardiovascular system is poorly understood. Prostacyclin, the predominant prostanoid released by vascular cells, is a putative endogenous agonist for PPARδ, but only recently PPARδ selective synthetic agonists were found, improving studies about the physiological and pathophysiological roles of PPARδ activation. Recent reports suggest that the PPARδ activation may play a pivotal role to regulate inflammation, apoptosis, and cell proliferation, suggesting that this transcriptional factor could become an interesting pharmacological target to regulate cardiovascular cell apoptosis, proliferation, inflammation, and metabolism.

Inhibition of protein kinase C-beta by ruboxistaurin preserves cardiac function and reduces extracellular matrix production in diabetic cardiomyopathy

BACKGROUND

Heart failure is a common cause of morbidity and mortality in diabetic patients that frequently manifests in the absence of impaired left ventricular systolic function. In contrast to the strong evidence base for the treatment of systolic heart failure, the treatment of heart failure with preserved left ventricular function is uncertain, and therapeutic targets beyond blockade of the renin-angiotensin-aldosterone and beta-adrenergic systems are being sought. One such target is the beta-isoform of protein kinase C (PKC), implicated in both the complications of diabetes and in cardiac dysfunction in the nondiabetic setting.

METHODS AND RESULTS

Using a hemodynamically validated rodent model of diabetic diastolic heart failure, the (mRen-2)27 transgenic rat, we sought to determine whether selective inhibition of PKC-beta would preserve cardiac function and reduce structural injury. Diabetic rats were randomized to receive either vehicle or the PKC-beta inhibitor, ruboxistaurin (20 mg/kg per d) and followed for 6 weeks. Compared with untreated animals, ruboxistaurin-treated diabetic rats demonstrated preserved systolic and diastolic function, as measured by the slope of preload recruitable stroke work relationship (P<0.05) and the slope of the end-diastolic pressure volume relationship (P<0.01). Collagen I deposition and cardiomyocyte hypertrophy were both reduced in diabetic animals treated with ruboxistaurin (P<0.01), as was phosphorylated-Smad2, an index of transforming growth factor-beta activity (P<0.01 for all, versus untreated diabetic rats).

CONCLUSIONS

PKC-ss inhibition attenuated diastolic dysfunction, myocyte hypertrophy, and collagen deposition and preserved cardiac contractility. PKC-beta inhibition may represent a novel therapeutic strategy for the prevention of diabetes-associated cardiac dysfunction.

Treatment of hypertension in heart failure with preserved ejection fraction: role of the kidney

Heart failure can present clinically as primarily diastolic or systolic dysfunction or both. There is an increasing awareness that heart failure can occur in the presence of a normal left ventricular ejection fraction. Heart failure with normal left ventricular ejection fraction is frequently referred to as diastolic heart failure because of the presence of diastolic left ventricular dysfunction evident from impaired left ventricular relaxation. This article focuses on the treatment of hypertension and the role the kidney plays in selecting appropriate agents.

Differential roles of cardiomyocyte and macrophage peroxisome proliferator-activated receptor gamma in cardiac fibrosis

OBJECTIVE

Cardiac fibrosis is an important component of diabetic cardiomyopathy. Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands repress proinflammatory gene expression, including that of osteopontin, a known contributor to the development of myocardial fibrosis. We thus investigated the hypothesis that PPARgamma ligands could attenuate cardiac fibrosis.

RESEARCH DESIGN AND METHODS

Wild-type cardiomyocyte- and macrophage-specific PPARgamma(-/-) mice were infused with angiotensin II (AngII) to promote cardiac fibrosis and treated with the PPARgamma ligand pioglitazone to determine the roles of cardiomyocyte and macrophage PPARgamma in cardiac fibrosis.

RESULTS

Cardiomyocyte-specific PPARgamma(-/-) mice (cPPARgamma(-/-)) developed spontaneous cardiac hypertrophy with increased ventricular osteopontin expression and macrophage content, which were exacerbated by AngII infusion. Pioglitazone attenuated AngII-induced fibrosis, macrophage accumulation, and osteopontin expression in both wild-type and cPPARgamma(-/-) mice but induced hypertrophy in a PPARgamma-dependent manner. We pursued two mechanisms to explain the antifibrotic cardiomyocyte-PPARgamma-independent effects of pioglitazone: increased adiponectin expression and attenuation of proinflammatory macrophage activity. Adenovirus-expressed adiponectin had no effect on cardiac fibrosis and the PPARgamma ligand pioglitazone did not attenuate AngII-induced cardiac fibrosis, osteopontin expression, or macrophage accumulation in monocyte-specific PPARgamma(-/-) mice.

CONCLUSIONS

We arrived at the following conclusions: 1) both cardiomyocyte-specific PPARgamma deficiency and activation promote cardiac hypertrophy, 2) both cardiomyocyte and monocyte PPARgamma regulate cardiac macrophage infiltration, 3) inflammation is a key mediator of AngII-induced cardiac fibrosis, 4) macrophage PPARgamma activation prevents myocardial macrophage accumulation, and 5) PPARgamma ligands attenuate AngII-induced cardiac fibrosis by inhibiting myocardial macrophage infiltration. These observations have important implications for potential interventions to prevent cardiac fibrosis.

Role of the renin-angiotensin system in age-related sarcopenia and diastolic dysfunction

The purpose of this review is to describe how recent pharmacological and genetic studies have contributed to our understanding of the role of the renin-angiotensin system (RAS) in age-related sarcopenia and diastolic dysfunction. Treatment strategies are limited in the context of both of these conditions, although interventions, which include blockade of the RAS (using angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers) are successful and lead to improvements in functional outcomes that are not necessarily mediated by hemodynamic effects of the drugs. Studies in animal models of sarcopenia and diastolic dysfunction point to ubiquitous effects of RAS blockade on multiple biological mechanisms, including inflammation, oxidative damage and metabolic dysregulation. Therefore, a re-evaluation of the use of these drugs in other conditions should be considered for maintaining functional independence in older individuals.