Targeted HFpEF therapy based on matchmaking of human and animal models

Searching for Effective Treatments in HFpEF: Implications for Modeling the Disease in Rodents

BACKGROUND

While the prevalence of heart failure with preserved ejection fraction (HFpEF) has increased over the last two decades, there still remains a lack of effective treatment. A key therapeutic challenge is posed by the absence of animal models that accurately replicate the complexities of HFpEF. The present review summarizes the effects of a wide spectrum of therapeutic agents on HF.

METHODS

Two online databases were searched for studies; in total, 194 experimental protocols were analyzed following the PRISMA protocol.

RESULTS

A diverse range of models has been proposed for studying therapeutic interventions for HFpEF, with most being based on pressure overload and systemic hypertension. They have been used to evaluate more than 150 different substances including ARNIs, ARBs, HMGR inhibitors, SGLT-2 inhibitors and incretins. Existing preclinical studies have primarily focused on LV diastolic performance, and this has been significantly improved by a wide spectrum of candidate therapeutic agents. Few experiments have investigated the normalization of pulmonary congestion, exercise capacity, animal mortality, or certain molecular hallmarks of heart disease.

CONCLUSIONS

The development of comprehensive preclinical HFpEF models, with multi-organ system phenotyping and physiologic stress-based functional testing, is needed for more successful translation of preclinical research to clinical trials.

Efficacy of a growth hormone-releasing hormone agonist in a murine model of cardiometabolic heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) represents a major unmet medical need owing to its diverse pathophysiology and lack of effective therapies. Potent synthetic, agonists (MR-356 and MR-409) of growth hormone-releasing hormone (GHRH) improve the phenotype of models of HF with reduced ejection fraction (HFrEF) and in cardiorenal models of HFpEF. Endogenous GHRH exhibits a broad range of regulatory influences in the cardiovascular (CV) system and aging and plays a role in several cardiometabolic conditions including obesity and diabetes. Whether agonists of GHRH can improve the phenotype of cardiometabolic HFpEF remains untested and unknown. Here we tested the hypothesis that MR-356 can mitigate/reverse the cardiometabolic HFpEF phenotype. C57BL6N mice received a high-fat diet (HFD) plus the nitric oxide synthase inhibitor (l-NAME) for 9 wk. After 5 wk of HFD + l-NAME regimen, animals were randomized to receive daily injections of MR-356 or placebo during a 4-wk period. Control animals received no HFD + l-NAME or agonist treatment. Our results showed the unique potential of MR-356 to treat several HFpEF-like features including cardiac hypertrophy, fibrosis, capillary rarefaction, and pulmonary congestion. MR-356 improved cardiac performance by improving diastolic function, global longitudinal strain (GLS), and exercise capacity. Importantly, the increased expression of cardiac pro-brain natriuretic peptide (pro-BNP), inducible nitric oxide synthase (iNOS), and vascular endothelial growth factor-A (VEGF-A) was restored to normal levels suggesting that MR-356 reduced myocardial stress associated with metabolic inflammation in HFpEF. Thus, agonists of GHRH may be an effective therapeutic strategy for the treatment of cardiometabolic HFpEF phenotype.NEW & NOTEWORTHY This randomized study used rigorous hemodynamic tools to test the efficacy of a synthetic GHRH agonist to improve cardiac performance in a cardiometabolic HFpEF. Daily injection of the GHRH agonist, MR-356, reduced the HFpEF-like effects as evidenced by improved diastolic dysfunction, reduced cardiac hypertrophy, fibrosis, and pulmonary congestion. Notably, end-diastolic pressure and end-diastolic pressure-volume relationship were reset to control levels. Moreover, treatment with MR-356 increased exercise capacity and reduced myocardial stress associated with metabolic inflammation in HFpEF.

Inflamed adipose tissue: A culprit underlying obesity and heart failure with preserved ejection fraction

The incidence of heart failure with preserved ejection fraction is increasing in patients with obesity, diabetes, hypertension, and in the aging population. However, there is a lack of adequate clinical treatment. Patients with obesity-related heart failure with preserved ejection fraction display unique pathophysiological and phenotypic characteristics, suggesting that obesity could be one of its specific phenotypes. There has been an increasing recognition that overnutrition in obesity causes adipose tissue expansion and local and systemic inflammation, which consequently exacerbates cardiac remodeling and leads to the development of obese heart failure with preserved ejection fraction. Furthermore, overnutrition leads to cellular metabolic reprogramming and activates inflammatory signaling cascades in various cardiac cells, thereby promoting maladaptive cardiac remodeling. Growing evidence indicates that the innate immune response pathway from the NLRP3 inflammasome, to interleukin-1 to interleukin-6, is involved in the generation of obesity-related systemic inflammation and heart failure with preserved ejection fraction. This review established the existence of obese heart failure with preserved ejection fraction based on structural and functional changes, elaborated the inflammation mechanisms of obese heart failure with preserved ejection fraction, proposed that NLRP3 inflammasome activation may play an important role in adiposity-induced inflammation, and summarized the potential therapeutic approaches.

Chronic high-rate pacing induces heart failure with preserved ejection fraction-like phenotype in Ossabaw swine

The lack of pre-clinical large animal models of heart failure with preserved ejection fraction (HFpEF) remains a growing, yet unmet obstacle to improving understanding of this complex condition. We examined whether chronic cardiometabolic stress in Ossabaw swine, which possess a genetic propensity for obesity and cardiovascular complications, produces an HFpEF-like phenotype. Swine were fed standard chow (lean; n = 13) or an excess calorie, high-fat, high-fructose diet (obese; n = 16) for ~ 18 weeks with lean (n = 5) and obese (n = 8) swine subjected to right ventricular pacing (180 beats/min for ~ 4 weeks) to induce heart failure (HF). Baseline blood pressure, heart rate, LV end-diastolic volume, and ejection fraction were similar between groups. High-rate pacing increased LV end-diastolic pressure from ~ 11 ± 1 mmHg in lean and obese swine to ~ 26 ± 2 mmHg in lean HF and obese HF swine. Regression analyses revealed an upward shift in LV diastolic pressure vs. diastolic volume in paced swine that was associated with an ~ twofold increase in myocardial fibrosis and an ~ 50% reduction in myocardial capillary density. Hemodynamic responses to graded hemorrhage revealed an ~ 40% decrease in the chronotropic response to reductions in blood pressure in lean HF and obese HF swine without appreciable changes in myocardial oxygen delivery or transmural perfusion. These findings support that high-rate ventricular pacing of lean and obese Ossabaw swine initiates underlying cardiac remodeling accompanied by elevated LV filling pressures with normal ejection fraction. This distinct pre-clinical tool provides a unique platform for further mechanistic and therapeutic studies of this highly complex syndrome.

Cardiac micro-RNA and transcriptomic profile of a novel swine model of chronic kidney disease and left ventricular diastolic dysfunction

Chronic kidney disease (CKD) is an independent risk factor for the development of heart failure, but the underlying mechanisms remain unknown. Using a novel translational swine model of CKD and cardiac dysfunction, we hypothesize that CKD alters the cardiac miRNA and transcriptomic profile that associate with cardiac remodeling and metabolic processes implicated in the development of left ventricular diastolic dysfunction (CKD-LVDD). CKD-LVDD and normal control pigs (n = 6 each) were studied for 14 wk. Renal and cardiac hemodynamics were quantified by multidetector CT and echocardiography. In randomly selected pigs (n = 3/group), cardiac miRNA- and mRNA-sequencing (seq) was performed, validated (qPCR), and followed by confirmatory ex vivo studies. Differential expression analysis identified nine miRNAs and 125 mRNAs upregulated and 17 miRNAs and 172 mRNAs downregulated [fold-change ≥ 2, and false discovery rate (FDR) ≤ 0.05] in CKD-LVDD versus normal controls. Integrated miRNA-/mRNA-seq analysis identified 71 overlappings downregulated mRNA targets of miRNAs upregulated, and 39 overlappings upregulated mRNA targets of miRNAs downregulated in CKD-LVDD versus controls. Functional analysis showed that these genes were primarily implicated in processes associated with cardiac remodeling, including ubiquitination, ATP and fatty acid synthesis, and extracellular matrix remodeling. In agreement, hearts of CKD-LVDD pigs exhibited abnormal diastolic relaxation, mitochondrial injury, moderate LV fibrosis, and myocardial lipid accumulation. Our work comprehensively characterizes the cardiac micro-RNA and transcriptomic profile of a translational model of CKD-LVDD. Our data may set the foundation for new targeted studies to further elucidate LVDD pathophysiology and assist to develop therapeutic interventions.NEW & NOTEWORTHY Chronic kidney disease (CKD) is a progressive disorder in which more than 50% of deaths are attributed to cardiovascular disease. Using a swine model of CKD that develops left ventricular dysfunction (CKD-LVDD), we characterize the cardiac micro-RNA and transcriptomic profile, identifying dysregulated genes associated with cardiac remodeling and fatty acid metabolism that might be post-transcriptionally regulated early in the disease. These findings pinpointed pathological pathways that may open new avenues toward therapeutic research to reduce cardiovascular morbidity in CKD.

Heart Failure With Preserved Ejection Fraction: Heterogeneous Syndrome, Diverse Preclinical Models

Heart failure with preserved ejection fraction (HFpEF) represents one of the greatest challenges facing cardiovascular medicine today. Despite being the most common form of heart failure worldwide, there has been limited success in developing therapeutics for this syndrome. This is largely due to our incomplete understanding of the biology driving its systemic pathophysiology and the heterogeneity of clinical phenotypes, which are increasingly being recognized as distinct HFpEF phenogroups. Development of efficacious therapeutics fundamentally relies on robust preclinical models that not only faithfully recapitulate key features of the clinical syndrome but also enable rigorous investigation of putative mechanisms of disease in the context of clinically relevant phenotypes. In this review, we propose a preclinical research strategy that is conceptually grounded in model diversification and aims to better align with our evolving understanding of the heterogeneity of clinical HFpEF. Although heterogeneity is often viewed as a major obstacle in preclinical HFpEF research, we challenge this notion and argue that embracing it may be the key to demystifying its pathobiology. Here, we first provide an overarching guideline for developing HFpEF models through a stepwise approach of comprehensive cardiac and extra-cardiac phenotyping. We then present an overview of currently available models, focused on the 3 leading phenogroups, which are primarily based on aging, cardiometabolic stress, and chronic hypertension. We discuss how well these models reflect their clinically relevant phenogroup and highlight some of the more recent mechanistic insights they are providing into the complex pathophysiology underlying HFpEF.

Skeletal myopathy in a rat model of postmenopausal heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) accounts for ∼50% of all patients with heart failure and frequently affects postmenopausal women. The HFpEF condition is phenotype-specific, with skeletal myopathy that is crucial for disease development and progression. However, most of the current preclinical models of HFpEF have not addressed the postmenopausal phenotype. We sought to advance a rodent model of postmenopausal HFpEF and examine skeletal muscle abnormalities therein. Female, ovariectomized, spontaneously hypertensive rats (SHRs) were fed a high-fat, high-sucrose diet to induce HFpEF. Controls were female sham-operated Wistar-Kyoto rats on a lean diet. In a complementary, longer-term cohort, controls were female sham-operated SHRs on a lean diet to evaluate the effect of strain difference in the model. Our model developed key features of HFpEF that included increased body weight, glucose intolerance, hypertension, cardiac hypertrophy, diastolic dysfunction, exercise intolerance, and elevated plasma cytokines. In limb skeletal muscle, HFpEF decreased specific force by 15%-30% (P < 0.05) and maximal mitochondrial respiration by 40%-55% (P < 0.05), increased oxidized glutathione by approximately twofold (P < 0.05), and tended to increase mitochondrial H2O2 emission (P = 0.10). Muscle fiber cross-sectional area, markers of mitochondrial content, and indices of capillarity were not different between control and HFpEF in our short-term cohort. Overall, our preclinical model of postmenopausal HFpEF recapitulates several key features of the disease. This new model reveals contractile and mitochondrial dysfunction and redox imbalance that are potential contributors to abnormal metabolism, exercise intolerance, and diminished quality of life in patients with postmenopausal HFpEF.NEW & NOTEWORTHY Heart failure with preserved ejection fraction (HFpEF) is a condition with phenotype-specific features highly prevalent in postmenopausal women and skeletal myopathy contributing to disease development and progression. We advanced a rat model of postmenopausal HFpEF with key cardiovascular and systemic features of the disease. Our study shows that the skeletal myopathy of postmenopausal HFpEF includes loss of limb muscle-specific force independent of atrophy, mitochondrial dysfunction, and oxidized shift in redox balance.

Optimizing the discovery and assessment of therapeutic targets in heart failure with preserved ejection fraction

There is an urgent need for models that faithfully replicate heart failure with preserved ejection fraction (HFpEF), now recognized as the most common form of heart failure in the world. In vitro approaches have several shortcomings, most notably the immature nature of stem cell‐derived human cardiomyocytes [induced pluripotent stem cells (iPSC)] and the relatively short lifespan of primary cardiomyocytes. Three‐dimensional ‘organoids’ incorporating mature iPSCs with other cell types such as endothelial cells and fibroblasts are a significant advance, but lack the complexity of true myocardium. Animal models can replicate many features of human HFpEF, and rodent models are the most common, and recent attempts to incorporate haemodynamic, metabolic, and ageing contributions are encouraging. Differences relating to species, physiology, heart rate, and heart size are major limitations for rodent models. Porcine models mitigate many of these shortcomings and approximate human physiology more closely, but cost and time considerations limit their potential for widespread use. Ex vivo analysis of failing hearts from animal models offer intriguing possibilities regarding cardiac substrate utilisation, but are ultimately subject to the same constrains as the animal models from which the hearts are obtained. Ex vivo approaches using human myocardial biopsies can uncover new insights into pathobiology leveraging myocardial energetics, substrate turnover, molecular changes, and systolic/diastolic function. In collaboration with a skilled cardiothoracic surgeon, left ventricular endomyocardial biopsies can be obtained at the time of valvular surgery in HFpEF patients. Critically, these tissues maintain their disease phenotype, preserving inter‐relationship of myocardial cells and extracellular matrix. This review highlights a novel approach, where ultra‐thin myocardial tissue slices from human HFpEF hearts can be used to assess changes in myocardial structure and function. We discuss current approaches to modelling HFpEF, describe in detail the novel tissue slice model, expand on exciting opportunities this model provides, and outline ways to improve this model further.

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.

Insights into therapeutic products, preclinical research models, and clinical trials in cardiac regenerative and reparative medicine: where are we now and the way ahead. Current opinion paper of the ESC Working Group on Cardiovascular Regenerative and Reparative Medicine

Great expectations have been set around the clinical potential of regenerative and reparative medicine in the treatment of cardiovascular diseases [i.e. in particular, heart failure (HF)]. Initial excitement, spurred by encouraging preclinical data, resulted in a rapid translation into clinical research. The sobering outcome of the resulting clinical trials suggests that preclinical testing may have been insufficient to predict clinical outcome. A number of barriers for clinical translation include the inherent variability of the biological products and difficulties to develop potency and quality assays, insufficient rigour of the preclinical research and reproducibility of the results, manufacturing challenges, and scientific irregularities reported in the last years. The failure to achieve clinical success led to an increased scrutiny and scepticism as to the clinical readiness of stem cells and gene therapy products among clinicians, industry stakeholders, and funding bodies. The present impasse has attracted the attention of some of the most active research groups in the field, which were then summoned to analyse the position of the field and tasked to develop a strategy, to re-visit the undoubtedly promising future of cardiovascular regenerative and reparative medicine, based on lessons learned over the past two decades. During the scientific retreat of the ESC Working Group on Cardiovascular Regenerative and Reparative Medicine (CARE) in November 2018, the most relevant and timely research aspects in regenerative and/or reparative medicine were presented and critically discussed, with the aim to lay out a strategy for the future development of the field. We report herein the main ideas and conclusions of that meeting.

The ubiquitin ligase WWP1 contributes to shifts in matrix proteolytic profiles and a myocardial aging phenotype with diastolic heart

Ubiquitylation is a key event that regulates protein turnover, and induction of the ubiquitin ligase E3 WWP1 has been associated with age. Left ventricular hypertrophy (LVH) commonly occurs as a function of age and can cause heart failure (HF) with a preserved ejection fraction (EF; HFpEF). We hypothesized that overexpression (O/E) of WWP1 in the heart would cause LVH as well as functional and structural changes consistent with the aging HFpEF phenotype. Global WWP1 O/E was achieved in mice (n = 11) and echocardiography (40 MHz) performed to measure LV mass, EF, Doppler velocities (early E, late/atrial A), myocardial relaxation (E'), and isovolumetric relaxation time (IVRT) at 4, 6, and 8 wk. Age-matched wild-type animals (n = 15) were included as referent controls. LV EF was identical (60 ± 1 vs. 60 ± 1%, P > 0.90) with no difference in LV mass (67 ± 3 vs. 75 ± 5, P > 0.25) at 4 wk. However, at 8 wk of age, LV mass increased over twofold, E/A fell (impaired passive filling), and E/E' was lower and IVRT prolonged (impaired LV relaxation) - all P < 0.05. Collagen percent area increased by over twofold and fibrillar collagen expression (RT-PCR) over 1.5-fold (P < 0.05) with WWP1 O/E. WWP1 with an anti-WWP1 antibody could be identified in isolated cardiac fibroblasts, with WWP1 increased over twofold in O/E fibroblasts (P < 0.05). Inducing WWP1 expression caused LVH and preserved systolic function but impaired diastolic dysfunction, consistent with the HFpEF phenotype. Targeting the WWP1 pathway may be a novel therapeutic target for this intractable form of HF associated with aging.NEW & NOTEWORTHY Heart failure (HF) with a preserved ejection fraction (HFpEF) is a growing cause of HF and commonly afflicts the elderly. Milestones for HFpEF include diastolic dysfunction and an abnormal extracelluar matrix (ECM). The ubiquitin ligases, such as WWP1, change with aging and regulate critical protein turnover/stability processes, such as the ECM. The present study demonstrated that induction of WWP1 in mice induced LV hypertrophy, diastolic dysfunction, and ECM accumulation, consistent with the HFpEF phenotype, and thus may identify a new therapeutic pathway.

Risk of bias in studies investigating novel diagnostic biomarkers for heart failure with preserved ejection fraction. A systematic review

Aim

Diagnosing heart failure with preserved ejection fraction (HFpEF) in the non‐acute setting remains challenging. Natriuretic peptides have limited value for this purpose, and a multitude of studies investigating novel diagnostic circulating biomarkers have not resulted in their implementation. This review aims to provide an overview of studies investigating novel circulating biomarkers for the diagnosis of HFpEF and determine their risk of bias (ROB).

Methods and results

A systematic literature search for studies investigating novel diagnostic HFpEF circulating biomarkers in humans was performed up until 21 April 2020. Those without diagnostic performance measures reported, or performed in an acute heart failure population were excluded, leading to a total of 28 studies. For each study, four reviewers determined the ROB within the QUADAS‐2 domains: patient selection, index test, reference standard, and flow and timing. At least one domain with a high ROB was present in all studies. Use of case‐control/two‐gated designs, exclusion of difficult‐to‐diagnose patients, absence of a pre‐specified cut‐off value for the index test without the performance of external validation, the use of inappropriate reference standards and unclear timing of the index test and/or reference standard were the main bias determinants. Due to the high ROB and different patient populations, no meta‐analysis was performed.

Conclusion

The majority of current diagnostic HFpEF biomarker studies have a high ROB, reducing the reproducibility and the potential for clinical care. Methodological well‐designed studies with a uniform reference diagnosis are urgently needed to determine the incremental value of circulating biomarkers for the diagnosis of HFpEF.

Deficit of resolution receptor magnifies inflammatory leukocyte directed cardiorenal and endothelial dysfunction with signs of cardiomyopathy of obesity

Chronic unresolved inflammation is the primary determinant of cardiovascular disease. Precise mechanisms that define the genesis of unresolved inflammation in heart failure with preserved ejection fraction (HFpEF) are of interest due to the obesity epidemic. To examine the obesity phenotype and its direct/indirect consequences, multiple approaches were employed using the lipoxin receptor (abbreviated as ALX) dysfunction mouse model. Indirect calorimetry analyses revealed that the deletion of ALX dysregulated energy metabolism driving toward age-related obesity. Heart function data suggest that obesity-prone ALX deficient mice had impaired myocardium strain. Comprehensive measurement of chemokines, extracellular matrix, and arrhythmogenic arrays confirmed the dysregulation of multiple ion channels gene expression with amplified inflammatory chemokines and cytokines response at the age of 4 months compared with WT counterparts. Quantitative analyses of leukocytes demonstrated an increase of proinflammatory Ly6C^hi CCR2⁺ macrophages in the spleen and heart at a steady-state resulting in an inflamed splenocardiac axis. Signs of subtle inflammation were marked with cardiorenal, endothelial defects with decreased CD31 and eNOS and an increased iNOS and COX2 expression. Thus, ALX receptor deficiency serves as an experimental model that defines multiple cellular and molecular mechanisms in HFpEF that could be a target for the development of HFpEF therapy in cardiovascular medicine.

The role of inflammation in driving left ventricular remodeling in a pre-HFpEF model

IMPACT STATEMENT

The incidence of HFpEF continues to increase and ∼2/3 of the patient population are post-menopausal women. Unfortunately, most studies focus on the use of male animal models of remodeling. In this study, however, using female rats to set a model of pre-HFpEF, we provide insights to possible mechanisms that contribute to HFpEF development in humans that will lead us to a better understanding of the underlying pathophysiology of HFpEF.

Unmasking of oestrogen-dependent changes in left ventricular structure and function in aged female rats: a potential model for pre-heart failure with preserved ejection fraction

KEY POINTS

Heart failure with preserved ejection fraction (HFpEF) is seen more frequently in older women; risk factors include age, hypertension and excess weight. No female animal models of early stage remodelling (pre-HFpEF) have examined the effects that the convergence of such factors have on cardiac structure and function. In this study, we demonstrate that ageing can lead to the development of mild chamber remodelling, diffuse fibrosis and loss of diastolic function. The loss of oestrogens further aggravates such changes by leading to a notable drop in cardiac output (while preserving normal ejection fraction) in the presence of diffuse fibrosis that is more predominant in endocardium and is accompanied by papillary fibrosis. Excess weight did not markedly aggravate such findings. This animal model recapitulates many of the features recognized in older, female HFpEF patients and thus, may serve to examine the effects of candidate therapeutic agents.

ABSTRACT

Two-thirds of patients with heart failure with preserved ejection fraction (HFpEF) are older women, and risk factors include hypertension and excess weight/obesity. Pathophysiological factors that drive early disease development (before heart failure ensues) remain obscure and female animal models are lacking. The study evaluated the intersecting roles of ageing, oestrogen depletion and excess weight on altering cardiac structure/function. Female, 18-month-old, Fischer F344 rats were divided into an aged group, aged + ovariectomy (OVX) and aged + ovariectomy + 10% fructose (OVF) in drinking water (n = 8-16/group) to induce weight gain. Left ventricular (LV) structure/function was monitored by echocardiography. At 22 months of age, animals were anaesthetized and catheter-based haemodynamics evaluated, followed by histological measures of chamber morphometry and collagen density. All aged animals developed hypertension. OVF animals increased body weight. Echocardiography only detected mild chamber remodelling with ageing while intraventricular pressure-volume loop analysis showed significant (P < 0.05) decreases vs. ageing in stroke volume (13% OVX and 15% for OVF), stroke work (34% and 52%) and cardiac output (29% and 27%), and increases in relaxation time (10% OVX) with preserved ejection fraction. Histology indicated papillary and interstitial fibrosis with ageing, which was higher in the endocardium of OVX and OVF groups. With ageing, ovariectomy leads to the loss of diastolic and global LV function while preserving ejection fraction. This model recapitulates many cardiovascular features present in HFpEF patients and may help understand the roles that ageing and oestrogen depletion play in early (pre-HFpEF) disease development.