Pirfenidone in Heart Failure with Preserved Ejection Fraction-Rationale and Design of the PIROUETTE Trial

Most UK cardiovascular disease trial protocols feature criteria that exclude ethnic minority participants: a systematic review

OBJECTIVES

We systematically reviewed UK cardiovascular disease (CVD) randomized controlled trial (RCT) protocols to identify the proportion featuring eligibility criteria that may disproportionately exclude ethnic minority (EM) participants.

METHODS

We searched MEDLINE, Embase, and Cochrane Library databases, January 2014-June 2022, to identify UK CVD RCT protocols. We extracted nonclinical eligibility criteria from trial protocols and inductively categorized the trials by their language, consent, and broad (ambiguous) criteria. Findings are narratively reported.

RESULTS

Of the seventy included RCT protocols, most (87.1%; 61/70) mentioned consent within the eligibility criteria, with more than two-thirds (68.9%; 42/61) indicating a requirement for 'written' consent. Alternative consent pathways that can aid EM participation were absent. English language requirement was present in 22.9% (16/70) of the studies and 37.1% (26/70) featured broad criteria that are open to interpretation and subject to recruiter bias. Only 4.3% (3/70) protocols mentioned the provision of translation services.

CONCLUSION

Most UK CVD trial protocols feature eligibility criteria that potentially exclude EM groups. Trial eligibility criteria must be situated within a larger inclusive recruitment framework, where ethnicity is considered alongside other intersecting and disadvantaging identities.

Pirfenidone increases transverse tubule length in the infarcted rat myocardium

Transverse (t)-tubule remodelling is a prominent feature of heart failure with reduced ejection fraction (HFrEF). In our previous research, we identified an increased amount of collagen within the t-tubules of HFrEF patients, suggesting fibrosis could contribute to the remodelling of t-tubules. In this research, we tested this hypothesis in a rodent model of myocardial infarction induced heart failure that was treated with the anti-fibrotic pirfenidone. Confocal microscopy demonstrated loss of t-tubules within the border zone region of the infarct. This was documented as a reduction in t-tubule frequency, area, length, and transverse elements. Eight weeks of pirfenidone treatment was able to significantly increase the area and length of the t-tubules within the border zone. Echocardiography showed no improvement with pirfenidone treatment. Surprisingly, pirfenidone significantly increased the thickness of the t-tubules in the remote left ventricle of heart failure animals. Dilation of t-tubules is a common feature in heart failure suggesting this may negatively impact function but there was no functional loss associated with pirfenidone treatment. However, due to the relatively short duration of treatment compared to that used clinically, the impact of long-term treatment on t-tubule structure should be investigated in future studies.

Towards refining of the proposed ECG-based index of coronary microvascular resistance (ECGMVR)

Assessment of the coronary microcirculation via noninvasive indices of coronary microvascular resistance (MVR), based on coronary angiography (AngioMVR) is currently implemented in patients undergoing coronary angiography, and it is employed by many laboratories. Recently, a proposal has been presented of a new index of MVR, based on the duration of the transient electrocardiogram repolarization and depolarization changes emerging during coronary angiography (ECGMVR). It is paramount that the ECGMVR, which does not require any special expertise, new equipment, additional personnel and costs, or prolongation of the catheterization procedure, undergoes correlation with currently utilized indices of AngioMVR, the TIMI frame count index, and the invasive indices assessing the coronary epicardial and microvasculature states, for its validation. Some additional insights are also included in the present communication for the refinement of ECGMVR implementation.

Pirfenidone affects human cardiac fibroblast proliferation and cell cycle activity in 2D cultures and engineered connective tissues

The anti-fibrotic drug pirfenidone (PFD) is currently in clinical testing for the treatment of heart failure with preserved ejection fraction; however, its effects on human cardiac cells have not been fully investigated. Therefore, we aimed to characterize the impact of PFD on human cardiac fibroblasts (CF) in 2D culture as well as in 3D-engineered connective tissues (ECT). We analyzed proliferation by automated cell counting and changes in signaling by immunoblotting. We generated ECT with different geometries to modify the cellular phenotype and investigated the effects of PFD on cell number and viability as well as on cell cycle activity. We further studied its effect on ECT compaction, contraction, stiffening, and strain resistance by ECT imaging, pole deflection analysis, and ultimate tensile testing. Our data demonstrate that PFD inhibits human CF proliferation in a concentration-dependent manner with an IC50 of 0.43 mg/ml and its anti-mitogenic effect was further corroborated by an inhibition of MEK1/2, ERK1/2, and riboprotein S6 (rpS6) phosphorylation. In ECT, a lower cell cycle activity was found in PFD-treated ECT and fewer cells resided in these ECT after 5 days of culture compared to the control. Moreover, ECT compaction as well as ECT contraction was impaired. Consequently, biomechanical analyses demonstrated that PFD reduced the stiffness of ECT. Taken together, our data demonstrate that the anti-fibrotic action of PFD on human CF is based on its anti-mitogenic effect in 2D cultures and ECT.

Cysteine-Based Redox-Responsive Nanoparticles for Fibroblast-Targeted Drug Delivery in the Treatment of Myocardial Infarction

Upon myocardial infarction (MI), activated cardiac fibroblasts (CFs) begin to remodel the myocardium, leading to cardiac fibrosis and even heart failure. No therapeutic approaches are currently available to prevent the development of MI-induced pathological fibrosis. Most pharmacological trials fail from poor local drug activity and side effects caused by systemic toxicity, largely due to the lack of a heart-targeted drug delivery system that is selective for activated CFs. Here, we developed a reduced glutathione (GSH)-responsive nanoparticle platform capable of targeted delivering of drugs to activated CFs within the infarct area of a post-MI heart. Compared with systemic drug administration, CF-targeted delivery of PF543, a sphingosine kinase 1 inhibitor identified in a high-throughput antifibrotic drug screening, had higher therapeutic efficacy and lower systemic toxicity in a MI mouse model. Our results provide a CF-targeted strategy to deliver therapeutic agents for pharmacological intervention of cardiac fibrosis.

Advances in Heart Failure with Preserved Ejection Fraction Management - The Role of Sacubitril-Valsartan, Pirfenidone, Spironolactone and Empagliflozin: Is Success a Series of Small Victories?

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is a syndrome characterized by marked heterogeneity in comorbidities and etiopathology substrates, leading to a diverse range of clinical manifestations and courses. Treatment options have been extremely limited and up to this day, there are virtually no pharmaceutical agents proven to reduce mortality in these patients.

OBJECTIVE

The primary objective of this narrative review is to critically summarize existing evidence regarding the use of Angiotensin Receptor-Neprilysin Inhibitor (ARNI), spironolactone, pirfenidone and empagliflozin in HFpEF.

METHODS

Medline (via PubMed) and Scopus were searched - from inception up to May 2022- using adequately selected keywords. Additional hand-search was also performed using the references of the articles identified as relevant (snowball strategy).

RESULTS

Angiotensin Receptor-Neprilysin Inhibitor (ARNI) and spironolactone, despite being very successful in HFrEF, did not do well in clinical trials of HFpEF, although there appear to be certain subsets of patients who may derive benefit. Data regarding pirfenidone are limited and come from small trials; as a result, it would be premature to draw firm conclusions, although it seems improbable that this agent will ever become a mainstay in the general population of HPpEF patients, while there may be a niche for the drug in individuals with comorbidities associated with an intense fibrotic activity. Finally, empagliflozin, largely welcomed as the first agent to have a "positive" randomized clinical trial in HFpEF, does not seem to evade the general pattern of reduced hospitalizations for HF with no substantial effect on mortality, seen in ARNI and spironolactone HFpEF trials.

CONCLUSION

Recent research in drug treatment for HFpEF has resulted in an overall mixed picture, with trials showing potential benefits from certain classes of drugs, such as sodium-glucose co-transporter 2 inhibitors, and no benefit from other drugs, which have shown to be effective in patient with reduced ejection fraction. However, small steps may be the way to go in HFpEF, and success is sometimes just a series of small victories.

Impact of Myocardial Fibrosis on Cardiovascular Structure, Function and Functional Status in Heart Failure with Preserved Ejection Fraction

Myocardial fibrosis, measured using cardiovascular magnetic resonance extracellular volume (ECV), is associated with adverse outcome in heart failure with preserved ejection fraction, but the mechanisms by which myocardial fibrosis exerts this deleterious effect are unclear. We performed mediation analyses of data from the Pirfenidone in Patients with Heart Failure and Preserved Left Ventricular Ejection Fraction (PIROUETTE) trial to determine whether myocardial fibrotic regression causes changes in cardiovascular function and functional status following antifibrotic therapy. Regression of myocardial fibrosis correlated with improvements in 6-min walk test and KCCQ clinical summary score. The only outcome variable that demonstrated a treatment effect was an increase in left ventricular ejection fraction (LVEF). The estimated average causal mediation effects of myocardial ECV, absolute myocardial extracellular matrix volume and absolute myocardial cellular volume on LVEF were 6.1%, 21.5% and 13.7%, respectively, none of which was significant and therefore not mediated by myocardial fibrosis. (PIROUETTE; NCT02932566).

The Future of Cardiac Magnetic Resonance Clinical Trials

Over the past 2 decades, cardiac magnetic resonance (CMR) has become an essential component of cardiovascular clinical care and contributed to imaging-guided diagnosis and management of coronary artery disease, cardiomyopathy, congenital heart disease, cardio-oncology, valvular, and vascular disease, amongst others. The widespread availability, safety, and capability of CMR to provide corresponding anatomical, physiological, and functional data in 1 imaging session can improve the design and conduct of clinical trials through both a reduction of sample size and provision of important mechanistic data that may augment clinical trial findings. Moreover, prospective imaging-guided strategies using CMR can enhance safety, efficacy, and cost-effectiveness of cardiovascular pathways in clinical practice around the world. As the future of large-scale clinical trial design evolves to integrate personalized medicine, cost-effectiveness, and mechanistic insights of novel therapies, the integration of CMR will continue to play a critical role. In this document, the attributes, limitations, and challenges of CMR's integration into the future design and conduct of clinical trials will also be covered, and recommendations for trialists will be explored. Several prominent examples of clinical trials that test the efficacy of CMR-imaging guided pathways will also be discussed.

Investigating the possible mechanisms of pirfenidone to be targeted as a promising anti-inflammatory, anti-fibrotic, anti-oxidant, anti-apoptotic, anti-tumor, and/or anti-SARS-CoV-2

Pirfenidone (PFD) is a non-peptide synthetic chemical that inhibits the production of transforming growth factor-beta 1 (TGF-β1), tumor necrosis factor-alpha (TNF-α), platelet-derived growth factor (PDGF), Interleukin 1 beta (IL-1β), and collagen 1 (COL1A1), all of which have been linked to the prevention or removal of excessive scar tissue deposition in many organs. PFD has been demonstrated to decrease apoptosis, downregulate angiotensin-converting enzyme (ACE) receptor expression, reduce inflammation through many routes, and alleviate oxidative stress in pneumocytes and other cells while protecting them from COVID-19 invasion and cytokine storm. Based on the mechanism of action of PFD and the known pathophysiology of COVID-19, it was recommended to treat COVID-19 patients. The use of PFD as a treatment for a range of disorders is currently being studied, with an emphasis on outcomes related to reduced inflammation and fibrogenesis. As a result, rather than exploring the molecule's chemical characteristics, this review focuses on innovative PFD efficacy data. Briefly, herein we tried to investigate, discuss, and illustrate the possible mechanisms of actions for PFD to be targeted as a promising anti-inflammatory, anti-fibrotic, anti-oxidant, anti-apoptotic, anti-tumor, and/or anti-SARS-CoV-2 candidate.

Pharmacological basis of the antifibrotic effects of pirfenidone: Mechanistic insights from cardiac in-vitro and in-vivo models

Pirfenidone is a small drug with marked antifibrotic activity approved for the treatment of Idiopathic pulmonary fibrosis. Recently, its peculiar pharmacological profile has attracted attention for its potential therapeutic benefit for extra-pulmonary disorders characterized by pathological fibrosis, such as kidney, liver, and cardiac failure. A major pitfall of pirfenidone is the lack of consistent understanding of its mechanism of action, regardless of the target. In addition to the increasing attention to the role of inflammation and its mediators in several processes, a better knowledge of the variety of fibroblasts' population, of signals controlling their activation and trans-differentiation, and of crosstalk with other cell resident and non-resident cell types is needed for prevention, treatment and possibly reverse of fibrosis. This review will focus on pirfenidone's pharmacological profile and its effects on cardiac fibroblasts.

Alleviation of cardiac fibrosis using acellular peritoneal matrix-loaded pirfenidone nanodroplets after myocardial infarction in rats

Myocardial fibrosis (MF) in the remote myocardium is a feature at the micoscopic level of pathological remodeling after myocardial infarction (MI). Although pirfenidone (PFD), an antifibrotic agent, is commonly used to inhibit fibrosis in multiple organs, its clinical use is limited because of the high doses required for favorable therapeutic outcomes and various side effects. Nanodrug technology has allowed for delayed quantitative drug release and reduced the amount of medication required, improving the treatment strategy for MF. In this study, we investigated the possible therapeutic effect of peritoneal matrix-loaded pirfenidone nanodroplets (NDs) on MI fibrosis. The results showed that the Perfluoropentane-Pirfenidone@Nanodroplets-Polyethylene glycol 2000 (PFP-PFD@NDs-PEG) described in this study was successfully synthesized and demonstrated a high potential for the targeted treatment of MI. The total duration of pirfenidone release from PFP-PFD@NDs-PEG was increased by loading it into an acellular peritoneal matrix (APM). Additionally, pirfenidone inhibited the transformation of cardiac fibroblasts into cardiac myofibroblasts in vitro and reduced the synthesis and secretion of collagen I and collagen III by cardiac myofibroblasts. The combination of the APM with pirfenidone nanodroplets achieved a slow drug release and showed excellent therapeutic effects on fibrosis in MI rats. Our study confirmed the feasibility and synergistic effectiveness of the APM combined with pirfenidone nanodroplets in the treatment of fibrosis in MI rats. Moreover, our technique offers a great potential for applying nanomedicine in other biomedical fields.

Research Progress of Myocardial Fibrosis and Atrial Fibrillation

With the aging population and the increasing incidence of basic illnesses such as hypertension and diabetes (DM), the incidence of atrial fibrillation (AF) has increased significantly. AF is the most common arrhythmia in clinical practice, which can cause heart failure (HF) and ischemic stroke (IS), increasing disability and mortality. Current studies point out that myocardial fibrosis (MF) is one of the most critical substrates for the occurrence and maintenance of AF. Although myocardial biopsy is the gold standard for evaluating MF, it is rarely used in clinical practice because it is an invasive procedure. In addition, serological indicators and imaging methods have also been used to evaluate MF. Nevertheless, the accuracy of serological markers in evaluating MF is controversial. This review focuses on the pathogenesis of MF, serological evaluation, imaging evaluation, and anti-fibrosis treatment to discuss the existing problems and provide new ideas for MF and AF evaluation and treatment.

Characteristics Associated With Growth Differentiation Factor 15 in Heart Failure With Preserved Ejection Fraction and the Impact of Pirfenidone

Background Growth differentiation factor 15 (GDF-15) is elevated in heart failure with preserved ejection fraction and is associated with adverse outcome, but its relationship with myocardial fibrosis and other characteristics remains unclear. We sought to evaluate the effect of pirfenidone, a novel antifibrotic agent, on GDF-15 in heart failure with preserved ejection fraction and identify characteristics that associate with GDF-15 and with change in GDF-15 over 1 year. Methods and Results Among patients enrolled (n=107) in the PIROUETTE (Pirfenidone in Patients With Heart Failure and Preserved Left Ventricular Ejection Fraction) trial, GDF-15 was measured at baseline and at prespecified time points in patients randomized (n=94) to pirfenidone or placebo. The response of GDF-15 to pirfenidone and the association with baseline patient characteristics were evaluated. Pirfenidone had no impact on circulating GDF-15 at any time point during the 52-week trial period. In multivariable analysis, male sex, diabetes, higher circulating levels of N-terminal pro-B-type natriuretic peptide, lower renal function, and shorter 6-minute walk test distance at baseline were associated with baseline log-GDF-15. Impaired global longitudinal strain at baseline was the strongest predictor of increased GDF-15 over 52 weeks. Conclusions In patients with heart failure with preserved ejection fraction, circulating levels of GDF-15 were unaffected by treatment with pirfenidone and do not appear to be determined by myocardial fibrosis. Circulating GDF-15 was associated with a spectrum of important heart failure characteristics and it may represent a marker of overall physiological disruption. Registration URL: https://clinicaltrials.gov/ct2/show/NCT02932566; Unique identifier: NCT02932566.

Association of Pulmonary Function With Late-Life Cardiac Function and Heart Failure Risk: The ARIC Study

Background Pulmonary and cardiac functions decline with age, but the associations of pulmonary dysfunction with cardiac function and heart failure (HF) risk in late life is not known. We aimed to determine the associations of percent predicted forced vital capacity (ppFVC) and the ratio of forced expired volume in 1 second (FEV₁) to forced vital capacity (FVC; FEV₁/FVC) with cardiac function and incident HF with preserved or reduced ejection fraction in late life. Methods and Results Among 3854 HF-free participants in the ARIC (Atherosclerosis Risk in Communities) cohort study who underwent echocardiography and spirometry at the fifth study visit (2011-2013), associations of FEV₁/FVC and ppFVC with echocardiographic measures, cardiac biomarkers, and risk of HF, HF with preserved ejection fraction, and HF with reduced ejection fraction were assessed. Multivariable linear and Cox regression models adjusted for demographics, body mass index, coronary disease, atrial fibrillation, hypertension, and diabetes. Mean age was 75±5 years, 40% were men, 19% were Black, and 61% were ever smokers. Mean FEV₁/FVC was 72±8%, and ppFVC was 98±17%. In adjusted analyses, lower FEV₁/FVC and ppFVC were associated with higher NT-proBNP (N-terminal pro-B-type natriuretic peptide; both P<0.001) and pulmonary artery pressure (P<0.004). Lower ppFVC was also associated with higher left ventricular mass, left ventricular filling pressure, and high-sensitivity C-reactive protein (all P<0.01). Lower FEV₁/FVC was associated with a trend toward higher risk of incident HF with preserved ejection fraction (hazard ratio [HR] per 10-point decrease, 1.31; 95% CI, 0.98-1.74; P=0.07) and HF with reduced ejection fraction (HR per 10-point decrease, 1.24; 95% CI, 0.91-1.70; P=0.18), but these associations did not reach statistical significance. Lower ppFVC was associated with incident HF with preserved ejection fraction (HR per 10-unit decrease, 1.21; 95% CI, 1.04-1.41; P=0.013) but not with HF with reduced ejection fraction (HR per 10-unit decrease, 0.90; 95% CI, 0.76-1.07; P=0.24). Conclusions Subclinical reductions in FEV₁/FVC and ppFVC differentially associate with cardiac function and HF risk in late life.

Predictors of myocardial fibrosis and response to anti-fibrotic therapy in heart failure with preserved ejection fraction

Myocardial fibrosis, measured using magnetic resonance extracellular volume (ECV), associates with adverse outcome in heart failure with preserved ejection fraction (HFpEF). In the PIROUETTE (The Pirfenidone in Patients with Heart Failure and Preserved Left Ventricular Ejection Fraction) trial, the novel anti-fibrotic agent pirfenidone reduced myocardial fibrosis. We sought to identify baseline characteristics that associate with myocardial fibrotic burden, the change in myocardial fibrosis over a year, and predict response to pirfenidone in patients with HFpEF. Amongst patients enrolled in the PIROUETTE trial (n = 107), linear regression models were used to assess the relationship between baseline variables and baseline myocardial ECV, with change in myocardial ECV adjusting for treatment allocation, and to identify variables that modified the pirfenidone treatment effect. Body mass index, left atrial reservoir strain, haemoglobin and aortic distensibility were associated with baseline ECV in stepwise modelling, and systolic blood pressure, and log N-terminal pro B-type natriuretic peptide were associated with baseline ECV in clinically-guided modelling. QRS duration, left ventricular mass and presence of an infarct at baseline were associated with an increase in ECV from baseline to week 52. Whilst QRS duration, presence of an infarct, global longitudinal strain and left atrial strain modified the treatment effect of pirfenidone when considered individually, no variable modified treatment effect on multivariable modelling. Baseline characteristics were identified that associate with myocardial fibrosis and predict change in myocardial fibrosis. No variables that independently modify the treatment effect of pirfenidone were identified (PIROUETTE, NCT02932566).

Cardiac Fibrosis in the Pressure Overloaded Left and Right Ventricle as a Therapeutic Target

Myocardial fibrosis is a remodeling process of the extracellular matrix (ECM) following cardiac stress. "Replacement fibrosis" is a term used to describe wound healing in the acute phase of an injury, such as myocardial infarction. In striking contrast, ECM remodeling following chronic pressure overload insidiously develops over time as "reactive fibrosis" leading to diffuse interstitial and perivascular collagen deposition that continuously perturbs the function of the left (L) or the right ventricle (RV). Examples for pressure-overload conditions resulting in reactive fibrosis in the LV are systemic hypertension or aortic stenosis, whereas pulmonary arterial hypertension (PAH) or congenital heart disease with right sided obstructive lesions such as pulmonary stenosis result in RV reactive fibrosis. In-depth phenotyping of cardiac fibrosis has made it increasingly clear that both forms, replacement and reactive fibrosis co-exist in various etiologies of heart failure. While the role of fibrosis in the pathogenesis of RV heart failure needs further assessment, reactive fibrosis in the LV is a pathological hallmark of adverse cardiac remodeling that is correlated with or potentially might even drive both development and progression of heart failure (HF). Further, LV reactive fibrosis predicts adverse outcome in various myocardial diseases and contributes to arrhythmias. The ability to effectively block pathological ECM remodeling of the LV is therefore an important medical need. At a cellular level, the cardiac fibroblast takes center stage in reactive fibrotic remodeling of the heart. Activation and proliferation of endogenous fibroblast populations are the major source of synthesis, secretion, and deposition of collagens in response to a variety of stimuli. Enzymes residing in the ECM are responsible for collagen maturation and cross-linking. Highly cross-linked type I collagen stiffens the ventricles and predominates over more elastic type III collagen in pressure-overloaded conditions. Research has attempted to identify pro-fibrotic drivers causing fibrotic remodeling. Single key factors such as Transforming Growth Factor β (TGFβ) have been described and subsequently targeted to test their usefulness in inhibiting fibrosis in cultured fibroblasts of the ventricles, and in animal models of cardiac fibrosis. More recently, modulation of phenotypic behaviors like inhibition of proliferating fibroblasts has emerged as a strategy to reduce pathogenic cardiac fibroblast numbers in the heart. Some studies targeting LV reactive fibrosis as outlined above have successfully led to improvements of cardiac structure and function in relevant animal models. For the RV, fibrosis research is needed to better understand the evolution and roles of fibrosis in RV failure. RV fibrosis is seen as an integral part of RV remodeling and presents at varying degrees in patients with PAH and animal models replicating the disease of RV afterload. The extent to which ECM remodeling impacts RV function and thus patient survival is less clear. In this review, we describe differences as well as common characteristics and key players in ECM remodeling of the LV vs. the RV in response to pressure overload. We review pre-clinical studies assessing the effect of anti-fibrotic drug candidates on LV and RV function and their premise for clinical testing. Finally, we discuss the mode of action, safety and efficacy of anti-fibrotic drugs currently tested for the treatment of left HF in clinical trials, which might guide development of new approaches to target right heart failure. We touch upon important considerations and knowledge gaps to be addressed for future clinical testing of anti-fibrotic cardiac therapies.

Pirfenidone Has Anti-fibrotic Effects in a Tissue-Engineered Model of Human Cardiac Fibrosis

A fundamental process in the development and progression of heart failure is fibrotic remodeling, characterized by excessive deposition of extracellular matrix proteins in response to injury. Currently, therapies that effectively target and reverse cardiac fibrosis are lacking, warranting novel therapeutic strategies and reliable methods to study their effect. Using a gelatin methacryloyl hydrogel, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and human fetal cardiac fibroblasts (hfCF), we developed a multi-cellular mechanically tunable 3D in vitro model of human cardiac fibrosis. This model was used to evaluate the effects of a promising anti-fibrotic drug-pirfenidone-and yields proof-of-concept of the drug testing potential of this platform. Our study demonstrates that pirfenidone has anti-fibrotic effects but does not reverse all TGF-β1 induced pro-fibrotic changes, which provides new insights into its mechanism of action.

Attenuation of Myocardial Fibrosis Using Molecular Hydrogen by Inhibiting the TGF-β Signaling Pathway in Spontaneous Hypertensive Rats

BACKGROUND

Previous studies have shown that hydrogen can antagonize the fibrosis of various organs. We investigated whether hydrogen-rich saline (HRS) can attenuate myocardial fibrosis in spontaneously hypertensive rats (SHRs) and clarified the mechanisms involved.

METHODS

We examined the effect of HRS and pirfenidone (PFD) on myocardial fibrosis in SHR. Systolic blood pressure, left ventricular mass index (LVMI), and heart weight index (HWI) were measured, Masson trichrome staining was performed. We assessed the role of superoxide dismutase (SOD), malondialdehyde (MDA), Alpha-smooth muscle actin (α-SMA), collagen I, collagen III, and tissue inhibitors of metalloproteinases (TIMPs) in myocardium. We detected the concentrations of procollagen type-I C-terminal propeptide (PICP), procollagen type-III N-terminal propeptide (PIIINP), and angiotensin II (Ang II) in rat serum. Furthermore, the relative protein levels of the transforming growth factor beta (TGF-β)/Smad pathway were tested.

RESULTS

We discovered that HRS decreases LVMI (P < 0.05) and HWI (P < 0.05) in vivo. Compared with model group, HRS decreases the level of collagen volume fraction (P < 0.0001), collagen I (P < 0.001), and collagen III (P < 0.001) in myocardium, and Ang II (P < 0.05), PICP (P < 0.001), and PIIINP (P < 0.05) in serum. In addition, HRS downregulates the expression of MDA (P < 0.01), α-SMA (P < 0.05), and TIMPs (P < 0.05), and increased SOD (P < 0.05). Furthermore, HRS downregulated the expression levels of TGF-β1 (P < 0.0001), Smad3 (P < 0.0001), and Smad2/3 (P < 0.001), but had no effect on Smad7 expression (P > 0.05). PFD had similar effect compared with HRS and control group.

CONCLUSIONS

HRS reduced oxidative stress and improved myocardial collagen content, which may be related to inhibition of the TGF-β signaling pathway. This suggests that HRS is an effective therapeutic strategy for myocardial fibrosis.

Myocardial fibrosis in congenital heart disease

Myocardial fibrosis resulting from the excessive deposition of collagen fibers through the myocardium is a common histopathologic finding in a wide range of cardiovascular diseases, including congenital anomalies. Interstitial fibrosis has been identified as a major cause of myocardial dysfunction since it distorts the normal architecture of the myocardium and impairs the biological function and properties of the interstitium. This review summarizes current knowledge on the mechanisms and detrimental consequences of myocardial fibrosis in heart failure and arrhythmias, discusses the usefulness of available imaging techniques and circulating biomarkers to assess this entity and reviews the current body of evidence regarding myocardial fibrosis in the different subsets of congenital heart diseases with implications in research and treatment.

Development of Anti-fibrotic Therapy in Stricturing Crohn's Disease: Lessons from Randomized Trials in Other Fibrotic Diseases

Intestinal fibrosis is considered an inevitable complication of Crohn's disease (CD) that results in symptoms of obstruction and stricture formation. Endoscopic or surgical treatment is required to treat the majority of patients. Progress in the management of stricturing CD is hampered by the lack of effective anti-fibrotic therapy; however, this situation is likely to change because of recent advances in other fibrotic diseases of the lung, liver and skin. In this review, we summarized data from randomized controlled trials (RCT) of anti-fibrotic therapies in these conditions. Multiple compounds have been tested for the anti-fibrotic effects in other organs. According to their mechanisms, they were categorized into growth factor modulators, inflammation modulators, 5-hydroxy-3-methylgultaryl-coenzyme A (HMG-CoA) reductase inhibitors, intracellular enzymes and kinases, renin-angiotensin system (RAS) modulators and others. From our review of the results from the clinical trials and discussion of their implications in the gastrointestinal tract, we have identified several molecular candidates that could serve as potential therapies for intestinal fibrosis in CD.

The Potential Therapeutic Role of Celastrol in Patients With Heart Failure With Preserved Ejection Fraction

Analysis of left ventricular systolic dysfunction remained at the centre of heart failure research for many years (also known as heart failure with reduced ejection fraction, HFrEF). Although more than 50% of all heart failure patients experience a form of heart failure characterised by preserved ejection fraction (HFpEF), the pathophysiological mechanisms leading to this form of heart failure remain not well-understood. Several evidence-based treatments for HFrEF are in routine use, but there are limited evidence-based therapies for HFpEF. The effects of these remain controversial, with current treatment options being limited to managing the associated symptoms and conditions. Accumulating evidence demonstrates that pro-inflammatory and oxidative stress pathways play key roles in the development and progression of HFpEF, such as the Unfolded Protein Response (UPR) and inducible nitric oxide synthase. Celastrol, derived from medicinal plants, is a bioactive compound with strong anti-inflammatory properties, which could deem it as fruitful in overcoming the effects of such dysregulated UPR. This literature review therefore focuses on Celastrol's anti-inflammatory and antioxidant activities, alongside its other potential therapeutic activities, and its ability to impede the pathways that are thought to be involved in the development of HFpEF, such as the JAK2/STAT pathway, to elucidate the potential therapeutic role of this bioactive compound, in the treatment of HFpEF.

Traditional Chinese medicine as a therapeutic option for cardiac fibrosis: Pharmacology and mechanisms

Cardiovascular diseases are one of the leading causes of death worldwide and cardiac fibrosis is a common pathological process for cardiac remodeling in cardiovascular diseases. Cardiac fibrosis not only accelerates the deterioration progress of diseases but also becomes a pivotal contributor for futile treatment in clinical cardiovascular trials. Although cardiac fibrosis is common and prevalent, effective medicines to provide sufficient clinical intervention for cardiac fibrosis are still unavailable. Traditional Chinese medicine (TCM) is the natural essence experienced boiling, fry, and other processing methods, including active ingredients, extracts, and herbal formulas, which have been applied to treat human diseases for a long history. Recently, research has increasingly focused on the great potential of TCM for the prevention and treatment of cardiac fibrosis. Here, we aim to clarify the identified pro-fibrotic mechanisms and intensively summarize the application of TCM in improving cardiac fibrosis by working on these mechanisms. Through comprehensively analyzing, TCM mainly regulates the following pathways during ameliorating cardiac fibrosis: attenuation of inflammation and oxidative stress, inhibition of cardiac fibroblasts activation, reduction of extracellular matrix accumulation, modulation of the renin-angiotensin-aldosterone system, modulation of autophagy, regulation of metabolic-dependent mechanisms, and targeting microRNAs. We also discussed the deficiencies and the development direction of anti-fibrotic therapies on cardiac fibrosis. The data reviewed here demonstrates that TCM shows a robust effect on alleviating cardiac fibrosis, which provides us a rich source of new drugs or drug candidates. Besides, we also hope this review may give some enlightenment for treating cardiac fibrosis in clinical practice.

Pirfenidone in heart failure with preserved ejection fraction: a randomized phase 2 trial

In heart failure with preserved ejection fraction (HFpEF), the occurrence of myocardial fibrosis is associated with adverse outcome. Whether pirfenidone, an oral antifibrotic agent without hemodynamic effect, is efficacious and safe for the treatment of HFpEF is unknown. In this double-blind, phase 2 trial ( NCT02932566 ), we enrolled patients with heart failure, an ejection fraction of 45% or higher and elevated levels of natriuretic peptides. Eligible patients underwent cardiovascular magnetic resonance and those with evidence of myocardial fibrosis, defined as a myocardial extracellular volume of 27% or greater, were randomly assigned to receive pirfenidone or placebo for 52 weeks. Forty-seven patients were randomized to each of the pirfenidone and placebo groups. The primary outcome was change in myocardial extracellular volume, from baseline to 52 weeks. In comparison to placebo, pirfenidone reduced myocardial extracellular volume (between-group difference, -1.21%; 95% confidence interval, -2.12 to -0.31; P = 0.009), meeting the predefined primary outcome. Twelve patients (26%) in the pirfenidone group and 14 patients (30%) in the placebo group experienced one or more serious adverse events. The most common adverse events in the pirfenidone group were nausea, insomnia and rash. In conclusion, among patients with HFpEF and myocardial fibrosis, administration of pirfenidone for 52 weeks reduced myocardial fibrosis. The favorable effects of pirfenidone in patients with HFpEF will need to be confirmed in future trials.

IGF-1 protects against angiotensin II-induced cardiac fibrosis by targeting αSMA

The insulin-like growth factor 1 receptor (IGF-1R) signaling in cardiomyocytes is implicated in physiological hypertrophy and myocardial aging. Although fibroblasts account for a small amount of the heart, they are activated when the heart is damaged to promote cardiac remodeling. However, the role of IGF-1R signaling in cardiac fibroblasts is still unknown. In this study, we investigated the roles of IGF-1 signaling during agonist-induced cardiac fibrosis and evaluated the molecular mechanisms in cultured cardiac fibroblasts. Using an experimental model of cardiac fibrosis with angiotensin II/phenylephrine (AngII/PE) infusion, we found severe interstitial fibrosis in the AngII/PE infused myofibroblast-specific IGF-1R knockout mice compared to the wild-type mice. In contrast, low-dose IGF-1 infusion markedly attenuated AngII-induced cardiac fibrosis by inhibiting fibroblast proliferation and differentiation. Mechanistically, we demonstrated that IGF-1-attenuated AngII-induced cardiac fibrosis through the Akt pathway and through suppression of rho-associated coiled-coil containing kinases (ROCK)2-mediated α-smooth muscle actin (αSMA) expression. Our study highlights a novel function of the IGF-1/IGF-1R signaling in agonist-induced cardiac fibrosis. We propose that low-dose IGF-1 may be an efficacious therapeutic avenue against cardiac fibrosis.

Immune Cells and Immunotherapy for Cardiac Injury and Repair

Cardiac injury remains a major cause of morbidity and mortality worldwide. Despite significant advances, a full understanding of why the heart fails to fully recover function after acute injury, and why progressive heart failure frequently ensues, remains elusive. No therapeutics, short of heart transplantation, have emerged to reliably halt or reverse the inexorable progression of heart failure in the majority of patients once it has become clinically evident. To date, most pharmacological interventions have focused on modifying hemodynamics (reducing afterload, controlling blood pressure and blood volume) or on modifying cardiac myocyte function. However, important contributions of the immune system to normal cardiac function and the response to injury have recently emerged as exciting areas of investigation. Therapeutic interventions aimed at harnessing the power of immune cells hold promise for new treatment avenues for cardiac disease. Here, we review the immune response to heart injury, its contribution to cardiac fibrosis, and the potential of immune modifying therapies to affect cardiac repair.

Right ventricular diastolic dysfunction and failure: a review

Right ventricular diastolic dysfunction and failure (RVDDF) has been increasingly identified in patients with cardiovascular diseases, including heart failure and other diseases with cardiac involvement. It is unknown whether RVDDF exists as a distinct clinical entity; however, its presence and degree have been shown to be a sensitive marker of end-organ dysfunction related to multiple disease processes including systemic hypertension, pulmonary hypertension, heart failure, and endocrine disease. In this manuscript, we review issues pertaining to RVDDF including anatomic features of the right ventricle, physiologic measurements, RVDDF diagnosis, underlying mechanisms, clinical impact, and clinical management. Several unique features of RVDDF are also discussed.

The utility of cardiovascular imaging in heart failure with preserved ejection fraction: diagnosis, biological classification and risk stratification

Heart failure with preserved ejection fraction (HFpEF) does not exist as a singular clinical or pathological entity but as a syndrome encompassing a wide range of clinical and biological phenotypes. There is an urgent need to progress from the unsuccessful 'one-size-fits-all' approach to more precise disease classification, in order to develop targeted therapies, personalise risk stratification and guide future research. In this regard, this review discusses the current and emerging roles of cardiovascular imaging for the diagnosis of HFpEF, for distilling HFpEF into distinct disease entities according to underlying pathobiology and for risk stratification.

Rationale for the Use of Pirfenidone in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major public health problem with growing prevalence and poor outcomes, mainly due to the lack of an effective treatment. HFpEF pathophysiology is heterogeneous and complex. Recently a “new paradigm” has been proposed, suggesting that cardiovascular and non-cardiovascular coexisting comorbidities lead to a systemic inflammatory state, perturbing the physiology of the endothelium and the perivascular environment and engaging molecular pathways that ultimately converge to myocardial fibrosis. If inflammation and fibrosis are the “fil rouge” in the heterogeneous spectrum of HFpEF, anti-fibrotic and anti-inflammatory drugs may have a role in its treatment. Pirfenidone is an orally bioavailable drug with antifibrotic and anti-inflammatory properties already approved for the treatment of idiopathic pulmonary fibrosis. Pirfenidone has been recently tested in animal models of myocardial fibrosis with promising results. Here we will review the rationale underlying the potential therapeutic effect of Pirfenidone in HFpEF.

Molecular Mechanisms of Obesity-Linked Cardiac Dysfunction: An Up-Date on Current Knowledge

Obesity is defined as excessive body fat accumulation, and worldwide obesity has nearly tripled since 1975. Excess of free fatty acids (FFAs) and triglycerides in obese individuals promote ectopic lipid accumulation in the liver, skeletal muscle tissue, and heart, among others, inducing insulin resistance, hypertension, metabolic syndrome, type 2 diabetes (T2D), atherosclerosis, and cardiovascular disease (CVD). These diseases are promoted by visceral white adipocyte tissue (WAT) dysfunction through an increase in pro-inflammatory adipokines, oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and adverse changes in the gut microbiome. In the heart, obesity and T2D induce changes in substrate utilization, tissue metabolism, oxidative stress, and inflammation, leading to myocardial fibrosis and ultimately cardiac dysfunction. Peroxisome proliferator-activated receptors (PPARs) are involved in the regulation of carbohydrate and lipid metabolism, also improve insulin sensitivity, triglyceride levels, inflammation, and oxidative stress. The purpose of this review is to provide an update on the molecular mechanisms involved in obesity-linked CVD pathophysiology, considering pro-inflammatory cytokines, adipokines, and hormones, as well as the role of oxidative stress, inflammation, and PPARs. In addition, cell lines and animal models, biomarkers, gut microbiota dysbiosis, epigenetic modifications, and current therapeutic treatments in CVD associated with obesity are outlined in this paper.

Diffuse myocardial fibrosis: mechanisms, diagnosis and therapeutic approaches

Diffuse myocardial fibrosis resulting from the excessive deposition of collagen fibres through the entire myocardium is encountered in a number of chronic cardiac diseases. This lesion results from alterations in the regulation of fibrillary collagen turnover by fibroblasts, facilitating the excessive deposition of type I and type III collagen fibres within the myocardial interstitium and around intramyocardial vessels. The available evidence suggests that, beyond the extent of fibrous deposits, collagen composition and the physicochemical properties of the fibres are also relevant in the detrimental effects of diffuse myocardial fibrosis on cardiac function and clinical outcomes in patients with heart failure. In this regard, findings from the past 20 years suggest that various clinicopathological phenotypes of diffuse myocardial fibrosis exist in patients with heart failure. In this Review, we summarize the current knowledge on the mechanisms and detrimental consequences of diffuse myocardial fibrosis in heart failure. Furthermore, we discuss the validity and usefulness of available imaging techniques and circulating biomarkers to assess the clinicopathological variation in this lesion and to track its clinical evolution. Finally, we highlight the currently available and potential future therapeutic strategies aimed at personalizing the prevention and reversal of diffuse myocardial fibrosis in patients with heart failure.

Myocardial Fibrosis in Heart Failure: Anti-Fibrotic Therapies and the Role of Cardiovascular Magnetic Resonance in Drug Trials

All heart muscle diseases that cause chronic heart failure finally converge into one dreaded pathological process that is myocardial fibrosis. Myocardial fibrosis predicts major adverse cardiovascular events and death, yet we are still missing the targeted therapies capable of halting and/or reversing its progression. Fundamentally it is a problem of disproportionate extracellular collagen accumulation that is part of normal myocardial ageing and accentuated in certain disease states. In this article we discuss the role of cardiovascular magnetic resonance (CMR) imaging biomarkers to track fibrosis and collate results from the most promising animal and human trials of anti-fibrotic therapies to date. We underscore the ever-growing role of CMR in determining the efficacy of such drugs and encourage future trialists to turn to CMR when designing their surrogate study endpoints.

Stratified Treatment of Heart Failure with preserved Ejection Fraction: rationale and design of the STADIA-HFpEF trial

AIMS

High myocardial stiffness in heart failure with preserved ejection fraction (HFpEF) is attributed to comorbidity-induced structural and functional remodelling through inflammation and oxidative stress affecting coronary microvascular endothelial cells and cardiomyocytes, which augments interstitial fibrosis and cardiomyocyte stiffness. In murine and human HFpEF myocardium, sodium glucose co-transporter 2 (SGLT2) inhibition ameliorates cardiac microvascular endothelial cell and cardiomyocyte oxidative stress, while enhancing myocardial protein kinase G activity and lowering titin-based cardiomyocyte stiffness. Failure of previous HFpEF outcome trials refocuses attention to improving pathophysiological insight and trial design with better phenotyping of patients and matching of therapeutic targets to prevailing pathogenetic mechanisms. SGLT2 inhibition could represent a viable therapeutic option especially in HFpEF patients in whom high diastolic left ventricular (LV) stiffness is predominantly caused by elevated cardiomyocyte stiffness and associated endothelial dysfunction, whereas HFpEF patients with extensive myocardial fibrosis might be less responsive. This study aims to investigate a stratified treatment approach, using dapagliflozin in heart failure patients with preserved ejection fraction without evidence of significant myocardial fibrosis.

METHODS AND RESULTS

The Stratified Treatment to Ameliorate DIAstolic left ventricular stiffness in early Heart Failure with preserved Ejection Fraction (STADIA-HFpEF) is a Phase II, randomized, 2 × 2 crossover trial, evaluating the efficacy of 13 weeks of treatment with dapagliflozin 10 mg od in 26 patients with HFpEF, with normal cardiac magnetic resonance imaging-derived extracellular volume. The co-primary endpoint is echocardiographically derived change in E/e'/LV end-diastolic volume index and change in mean LV e'.

CONCLUSIONS

The STADIA-HFpEF trial will be the first study to evaluate the direct effects of dapagliflozin on amelioration of LV stiffness, using histological phenotyping to discern early HFpEF.

Targeting cardiac fibrosis in heart failure with preserved ejection fraction: mirage or miracle?

Cardiac fibrosis is central to the pathology of heart failure, particularly heart failure with preserved ejection fraction (HFpEF). Irrespective of the underlying profibrotic condition (e.g. ageing, diabetes, hypertension), maladaptive cardiac fibrosis is defined by the transformation of resident fibroblasts to matrix-secreting myofibroblasts. Numerous profibrotic factors have been identified at the molecular level (e.g. TGFβ, IL11, AngII), which activate gene expression programs for myofibroblast activation. A number of existing HF therapies indirectly target fibrotic pathways; however, despite multiple clinical trials in HFpEF, a specific clinically effective antifibrotic therapy remains elusive. Therapeutic inhibition of TGFβ, the master-regulator of fibrosis, has unfortunately proven toxic and ineffective in clinical trials to date, and new approaches are needed. In this review, we discuss the pathophysiology and clinical implications of interstitial fibrosis in HFpEF. We provide an overview of trials targeting fibrosis in HFpEF to date and discuss the promise of potential new therapeutic approaches and targets in the context of underlying molecular mechanisms.

Left ventricular dysfunction in heart failure with preserved ejection fraction-molecular mechanisms and impact on right ventricular function

The current classification of heart failure (HF) based on left ventricular (LV) ejection fraction (EF) identifies a large group of patients with preserved ejection fraction (HFpEF) with significant morbidity and mortality but without prognostic benefit from current HF therapy. Co-morbidities and conditions such as arterial hypertension, diabetes mellitus, chronic kidney disease, adiposity and aging shape the clinical phenotype and contribute to mortality. LV diastolic dysfunction and LV structural remodeling are hallmarks of HFpEF, and are linked to remodeling of the cardiomyocyte and extracellular matrix. Pulmonary hypertension (PH) and right ventricular dysfunction (RVD) are particularly common in HFpEF, and mortality is up to 10-fold higher in HFpEF patients with vs. without RV dysfunction. Here, we review alterations in cardiomyocyte function (i.e., ion homeostasis, sarcomere function and cellular metabolism) associated with diastolic dysfunction and summarize the main underlying cellular pathways. The contribution and interaction of systemic and regional upstream signaling such as chronic inflammation, neurohumoral activation, and NO-cGMP-related pathways are outlined in detail, and their diagnostic and therapeutic potential is discussed in the context of preclinical and clinical studies. In addition, we summarize prevalence and pathomechanisms of RV dysfunction in the context of HFpEF and discuss mechanisms connecting LV and RV dysfunction in HFpEF. Dissecting the molecular mechanisms of LV and RV dysfunction in HFpEF may provide a basis for an improved classification of HFpEF and for therapeutic approaches tailored to the molecular phenotype.

Cardiovascular implications of idiopathic pulmonary fibrosis: A way forward together?

Cardiovascular disease has an increased prevalence among patients with idiopathic pulmonary fibrosis (IPF). Cardiovascular disease and IPF share similar symptoms with overlapping demographics and risk factors for disease development. Common cellular mediators leading to disease development and progression have been identified in both the cardiovascular and pulmonary organ systems. In this context, discovery of new therapeutic targets and medical therapies could be mutually beneficial across cardiopulmonary diseases. Here we present (1) a clinical review of IPF for the cardiovascular clinician and (2) common cellular mechanisms responsible for fibrosis in the heart and lungs and (3) highlight future research considerations and the potential role of novel therapeutic agents which may be mutually beneficial in cardiac and pulmonary fibrosis.

Metabolic inflammation in heart failure with preserved ejection fraction

One in 10 persons in the world aged 40 years and older will develop the syndrome of HFpEF (heart failure with preserved ejection fraction), the most common form of chronic cardiovascular disease for which no effective therapies are currently available. Metabolic disturbance and inflammatory burden contribute importantly to HFpEF pathogenesis. The interplay within these two biological processes is complex; indeed, it is now becoming clear that the notion of metabolic inflammation-metainflammation-must be considered central to HFpEF pathophysiology. Inflammation and metabolism interact over the course of syndrome progression, and likely impact HFpEF treatment and prevention. Here, we discuss evidence in support of a causal, mechanistic role of metainflammation in shaping HFpEF, proposing a framework in which metabolic comorbidities profoundly impact cardiac metabolism and inflammatory pathways in the syndrome.

Effects of Pirfenidone on Echocardiographic Parameters of Left Ventricular Structure and Function in Patients with Idiopathic Pulmonary Fibrosis

Aim: Pirfenidone is a novel anti-fibrotic agent utilized in the treatment of idiopathic pulmonary fibrosis (IPF). It has been implicated in mitigating myocardial fibrosis and left ventricular (LV) systolic and diastolic dysfunction in animal models. However, its impact on LV mechanics in humans remains unknown. The aim of this study was to retrospectively evaluate the effects of pirfenidone on echocardiographic parameters of LV function and structure in patients with IPF.

Methods: A total of 124 patients with IPF were included in this study: 64 patients treated with pirfenidone (treatment group) and 60 patients not taking pirfenidone (control group), who had serial pretreatment/baseline and posttreatment/follow-up echocardiograms done within a time frame of four years. Changes in the means of parameters of LV function (systolic, diastolic, and global longitudinal strain) and LV structure (mass and volume indices) were compared between the treatment and control groups. This was followed by a subgroup analysis that included only 88 patients (47 treated, 41 controls) with echocardiographic evidence of myocardial dysfunction at baseline (defined as an ejection fraction of ≤45, or diastolic dysfunction stage 1 or more) in addition to a known clinical diagnosis of congestive heart failure. To account for potential confounders, a secondary adjusted analysis by way of 1:1 propensity score matching (PSM) was carried out. This yielded a sample consisting of 62 patients with 56 patients in the subgroup cohort.

Results: Patients in the treatment group were significantly younger (69.4 vs. 77 years, p<0.001) and had relatively lower forced vital capacity (69.9% vs. 80.6%, p = 0.005) in comparison to the control group. However, after PSM, the age demographics were comparable between both groups (72.18 vs. 72.15, p = 0.9). In the primary unadjusted analysis, there was no statistically significant change in any of the mean parameters of LV function and structure after pirfenidone administration when compared to the control group. Furthermore, no significant differences were noted in the subgroup cohort. Such findings were re-demonstrated after a secondary analysis with PSM.

Conclusion: From an echocardiographic perspective, pirfenidone had no significant effects on LV structure and function in patients with IPF, even in patients with more overt cardiac dysfunction.

Cardiac tissue remodeling in healthy aging: the road to pathology

This review aims to highlight the normal physiological remodeling that occurs in healthy aging hearts, including changes that occur in contractility, conduction, valve function, large and small coronary vessels, and the extracellular matrix. These "normal" age-related changes serve as the foundation that supports decreased plasticity and limited ability for tissue remodeling during pathophysiological states such as myocardial ischemia and heart failure. This review will identify populations at greater risk for poor tissue remodeling in advanced age along with present and future therapeutic strategies that may ameliorate dysfunctional tissue remodeling in aging hearts.

Characterizing heart failure with preserved and reduced ejection fraction: An imaging and plasma biomarker approach

Introduction

The pathophysiology of heart failure with preserved ejection fraction (HFpEF) remains incompletely defined. We aimed to characterize HFpEF compared to heart failure with reduced ejection fraction (HFrEF) and asymptomatic hypertensive or non-hypertensive controls.

Materials and methods

Prospective, observational study of 234 subjects (HFpEF n = 140; HFrEF n = 46, controls n = 48, age 73±8, males 49%) who underwent echocardiography, cardiovascular magnetic resonance imaging (CMR), plasma biomarker analysis (panel of 22) and 6-minute walk testing (6MWT). The primary end-point was the composite of all-cause mortality and/or HF hospitalization.

Results

Compared to controls both HF groups had lower exercise capacity, lower left ventricular (LV) EF, higher LV filling pressures (E/E’, B-type natriuretic peptide [BNP], left atrial [LA] volumes), more right ventricular (RV) systolic dysfunction, more focal and diffuse fibrosis and higher levels of all plasma markers. LV remodeling (mass/volume) was different between HFpEF (concentric, 0.68±0.16) and HFrEF (eccentric, 0.47±0.15); p<0.0001. Compared to controls, HFpEF was characterized by (mild) reductions in LVEF, more myocardial fibrosis, LA remodeling/dysfunction and RV dysfunction. HFrEF patients had lower LVEF, increased LV volumes, greater burden of focal and diffuse fibrosis, more RV remodeling, lower LAEF and higher LA volumes compared to HFpEF. Inflammatory/fibrotic/renal dysfunction plasma markers were similarly elevated in both HF groups but markers of cardiomyocyte stretch/damage (BNP, pro-BNP, N-terminal pro-atrial natriuretic peptide and troponin-I) were higher in HFrEF compared to HFpEF; p<0.0001. Focal fibrosis was associated with galectin3, GDF-15, MMP-3, MMP-7, MMP-8, BNP, pro-BNP and NTproANP; p<0.05. Diffuse fibrosis was associated with GDF-15, Tenascin-C, MMP-2, MMP-3, MMP-7, BNP, proBNP and NTproANP; p<0.05. Composite event rates (median 1446 days follow-up) did not differ between HFpEF and HFrEF (Log-Rank p = 0.784).

Conclusions

HFpEF is a distinct pathophysiological entity compared to age- and sex-matched HFrEF and controls. HFpEF and HFrEF are associated with similar adverse outcomes. Inflammation is common in both HF phenotypes but cardiomyocyte stretch/stress is greater in HFrEF.

Therapeutic Targets for the Treatment of Cardiac Fibrosis and Cancer: Focusing on TGF-β Signaling

Transforming growth factor-β (TGF-β) is a common mediator of cancer progression and fibrosis. Fibrosis can be a significant pathology in multiple organs, including the heart. In this review, we explain how inhibitors of TGF-β signaling can work as antifibrotic therapy. After cardiac injury, profibrotic mediators such as TGF-β, angiotensin II, and endothelin-1 simultaneously activate cardiac fibroblasts, resulting in fibroblast proliferation and migration, deposition of extracellular matrix proteins, and myofibroblast differentiation, which ultimately lead to the development of cardiac fibrosis. The consequences of fibrosis include a wide range of cardiac disorders, including contractile dysfunction, distortion of the cardiac structure, cardiac remodeling, and heart failure. Among various molecular contributors, TGF-β and its signaling pathways which play a major role in carcinogenesis are considered master fibrotic mediators. In fact, recently the inhibition of TGF-β signaling pathways using small molecule inhibitors, antibodies, and gene deletion has shown that the progression of several cancer types was suppressed. Therefore, inhibitors of TGF-β signaling are promising targets for the treatment of tissue fibrosis and cancers. In this review, we discuss the molecular mechanisms of TGF-β in the pathogenesis of cardiac fibrosis and cancer. We will review recent in vitro and in vivo evidence regarding antifibrotic and anticancer actions of TGF-β inhibitors. In addition, we also present available clinical data on therapy based on inhibiting TGF-β signaling for the treatment of cancers and cardiac fibrosis.

Intra-study and inter-technique validation of cardiovascular magnetic resonance imaging derived left atrial ejection fraction as a prognostic biomarker in heart failure with preserved ejection fraction

The aim of this study was to assess the agreements of both biplane and short-axis Simpson’s (SAX) methods for left atrial ejection fraction (LAEF) calculation utilising cardiovascular magnetic resonance imaging (CMR) in heart failure with preserved ejection fraction (HFpEF) and evaluate their relation to clinical outcomes. One hundred and thirty six subjects (HFpEF n = 97, controls n = 39) underwent CMR, six-minute walk tests and blood sampling in our prospective, observational, single-centre study. Overall, LAEF (%) was lower in HFpEF patients compared to controls (SAX 34 ± 13 vs 47 ± 8, biplane 34 ± 16 vs 51 ± 11; p < 0.0001 for both). Atrial fibrillation (AF) was present in 24% of HFpEF and was associated with higher LA volumes and lower LAEF compared to sinus rhythm (p < 0.0001) with both methods. Biplane LAEF correlated strongly with SAX measurements (overall Pearson’s r = 0.851, sinus rhythm r = 0.651, AF r = 0.882; p < 0.0001). Biplane LAEF did not differ significantly compared to SAX LAEF (overall 34 ± 16 vs 34 ± 13%; p = 0.307) except in AF subjects in whom biplane LAEF was lower (mean difference 2 ± 4%, p = 0.013). There were 44 composite events (25 deaths, 19 HF hospitalizations) in HFpEF during median follow-up of 1429 days. LAEF below the median was associated with increased risk of composite endpoints (Log-Rank biplane p < 0.0001; SAX p = 0.009). In multivariable Cox proportional hazards regression analysis, both biplane LAEF (hazard ratio [HR] 0.604; 95% confidence interval [CI] (0.406–0.900); p = 0.013) and SAX LAEF (HR 0.636; CI 0.441–0.918; p = 0.016) remained independent predictors along with indexed extracellular volume. CMR LAEF, derived from either the short-axis or biplane method is lower in HFpEF compared to healthy controls and remains a strong marker of prognosis.

Pharmacological Inhibition of Serine Proteases to Reduce Cardiac Inflammation and Fibrosis in Atrial Fibrillation

Systemic inflammation correlates with an increased risk of atrial fibrillation (AF) and thrombogenesis. Systemic inflammation alters vessel permeability, allowing inflammatory and immune cell migration toward target organs, including the heart. Among inflammatory cells infiltrating the atria, macrophages and mast cell have recently attracted the interest of basic researchers due to the pathogenic mechanisms triggered by their activation. This chemotactic invasion is likely implicated in short- and long-term changes in cardiac cell-to-cell communication and in triggering fibrous tissue accumulation in the atrial myocardium and electrophysiological re-arrangements of atrial cardiomyocytes, thus favoring the onset and progression of AF. Serine proteases are a large and heterogeneous class of proteases involved in several processes that are important for cardiac function and are involved in cardiac diseases, such as (i) coagulation, (ii) fibrinolysis, (iii) extracellular matrix degradation, (iv) activation of receptors (i.e., protease-activated receptors [PPARs]), and (v) modulation of the activity of endogenous signals. The recognition of serine proteases substrates and their involvement in inflammatory/profibrotic mechanisms allowed the identification of novel cardio-protective mechanisms for commonly used drugs that inhibit serine proteases. The aim of this review is to summarize knowledge on the role of inflammation and fibrosis as determinants of AF. Moreover, we will recapitulate current findings on the role of serine proteases in the pathogenesis of AF and the possible beneficial effects of drugs inhibiting serine proteases in reducing the risk of AF through decrease of cardiac inflammation and fibrosis. These drugs include thrombin and factor Xa inhibitors (used as oral anticoagulants), dipeptidyl-peptidase 4 (DPP4) inhibitors, used for type-2 diabetes, as well as novel experimental inhibitors of mast cell chymases.

Left atrial ejection fraction and outcomes in heart failure with preserved ejection fraction

The aim of this study was to determine whether left atrial ejection fraction (LAEF) quantified with cardiovascular magnetic resonance (CMR) was different between heart failure with preserved ejection fraction (HFpEF) and controls, and its relation to prognosis. As part of our single-centre, prospective, observational study, 188 subjects (HFpEF n = 140, controls n = 48) underwent phenotyping with contrast-enhanced CMR, transthoracic echocardiography, blood sampling and six-minute walk testing. LAEF was calculated using the biplane method. Atrial fibrillation (AF) was present in 43 (31%) of HFpEF subjects. Overall, LAEF (%) was lower in HFpEF patients inclusive of AF (32 ± 16) or those in sinus rhythm alone (41 ± 12) compared to controls (51 ± 11), p < 0.0001. LAEF correlated inversely with maximal and minimal left atrial volumes indexed (r =  − 0.602, r =  − 0.762), and plasma N-terminal pro-atrial natriuretic peptide (r =  − 0.367); p < 0.0001. During median follow-up (1429 days), there were 67 composite events of all-cause death or hospitalization for heart failure (22 deaths, 45 HF hospitalizations) in HFpEF. Lower LAEF (below median) was associated with an increased risk of composite endpoints (Log-Rank: all p = 0.028; sinus p = 0.036). In multivariable Cox regression analysis, LAEF (adjusted hazard ratio [HR] 0.767, 95% confidence interval [CI] 0.591–0.996; p = 0.047) and indexed extracellular volume (HR 1.422, CI 1.015–1.992; p = 0.041) were the only parameters that remained significant when added to a base prognostic model comprising age, prior HF hospitalization, diastolic blood pressure, lung disease, NYHA, six-minute-walk-test-distance, haemoglobin, creatinine and B-type natriuretic peptide. CMR-derived LAEF is lower in HFpEF compared to healthy controls and is a strong prognostic biomarker.