Impaired Diastolic Relaxation Research Articles

Characterizing diabetic cardiomyopathy: baseline results from the ARISE-HF trial

BackgroundDiabetic cardiomyopathy (DbCM) is a form of Stage B heart failure (HF) at high risk for progression to overt disease. Using baseline characteristics of study participants from the Aldose Reductase Inhibition for Stabilization of Exercise Capacity in Heart Failure (ARISE-HF) Trial we sought to characterize clinical characteristics of individuals with findings consistent with DbCM.MethodsAmong study participants meeting inclusion criteria, clinical characteristics, laboratory testing, imaging, Kansas City Cardiomyopathy Questionnaire (KCCQ), Physical Activity Scale of the Elderly (PASE) and cardiopulmonary exercise testing (CPET) results were tabulated. Cluster phenogroups were identified.ResultsAmong 691 study participants (mean age 67.4 years; 50% were female), mean duration of type 2 diabetes mellitus (T2DM) was 14.5 years. The median (Q1, Q3) N-terminal pro-B type natriuretic peptide and high sensitivity cardiac troponin T were 71 (35, 135) ng/L and 9 [6, 12] ng/L. The most common echocardiographic abnormalities were reduced global longitudinal strain in 25.3% and impaired diastolic relaxation in 17.7%. Despite rather well-preserved KCCQ scores the average PASE score was markedly impaired at 155 accompanied by an average maximal oxygen consumption of 15.7 mL/Kg/minute on CPET. In K-means clustering, 4 phenogroups were identified including a higher-risk group with more advanced age, greater elevation of cardiac biomarkers, and more prevalent evidence for diastolic dysfunction and left ventricular hypertrophy.ConclusionsBaseline data from the ARISE-HF Trial provide clinical characterization of individuals with T2DM and features of stage B HF, and may help clarify the diagnosis of DbCM.Trial RegistrationARISE-HF, NCT04083339.

1238-P: The Face of Diabetic Cardiomyopathy—Baseline Characteristics from the ARISE-HF Trial

Background: Diabetic Cardiomyopathy (DbCM) is a severe complication of diabetes and a cause of heart failure (HF) occurring in the absence of other causes of cardiac dysfunction. Methods and Results: ARISE-HF (NCT04083339) is a global Phase 3 randomized study evaluating the safety and efficacy of a novel highly selective aldose reductase inhibitor (AT-001) versus placebo to improve exercise capacity in individuals with DbCM (defined by elevated cardiac biomarkers or structural/functional cardiac abnormalities along with impaired exercise capacity). Table 1 details the 684 study participants with DbCM in the study: 50% female, with a mean age 67.5 years. Glycemic control at enrollment was excellent (HbA1c of 6.99%). At baseline, the median NT-proBNP was 71 ng/L and hs-cTnT was 9 ng/L. Among echocardiographic abnormalities evaluated at enrollment, the most common were abnormal global longitudinal strain and impaired diastolic relaxation. Daily physical activity was low (mean PASE score of 154.3 + 89.6). Significant impairment in cardiac functional capacity was present at enrollment with a peak VO2 of 15.7 + 3.8 ml/kg/min. Conclusion: The ARISE-HF trial is an ongoing phase 3 clinical trial evaluating the safety and efficacy of aldose reductase inhibition on exercise capacity in patients with DbCM. The baseline analysis of the study cohort provides a unique characterization of individuals with DbCM. Disclosure J.Butler: Consultant; Abbott,, Amgen, Applied Therapeutics, Array, Astra Zeneca, Bayer,, Boehringer Ingelheim, Bristol Myers Squibb, CVRx, G3 Pharma,, Impulse Dynamics, Innolife, Janssen, LivaNova, Luitpold, Medtronic, Merck, Novartis, NovoNordisk, Relypsa, Roche, Sequana Medical, Vifor, Speaker's Bureau; Novartis, Boehringer Ingelheim-Lilly, Astra Zeneca, Janssen. F.Zannad: Advisory Panel; BMS, Novo Nordisk, Pfizer Inc., Servier Laboratories, Other Relationship; Applied Therapeutics Inc., Bayer Inc., Boehringer Ingelheim and Eli Lilly Alliance, Merck & Co., Inc., Novartis. J.L.Januzzi: Consultant; Boehringer Ingelheim Inc., Janssen Pharmaceuticals, Inc., AstraZeneca, Research Support; Applied Therapeutics Inc., Abbott, Roche Diagnostics, Novartis, Innolife Co., Ltd. S.Del prato: Advisory Panel; Abbott Diagnostics, Altimmune, Amarin Corporation, Applied Therapeutics Inc., Eli Lilly and Company, Merck & Co., Inc., Novo Nordisk A/S, Vertex Pharmaceuticals Incorporated, Novartis, Consultant; A. Menarini Diagnostics, Research Support; AstraZeneca, Boehringer Ingelheim International GmbH, Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Merck & Co., Inc., Novo Nordisk A/S, Sanofi. J.Ezekowitz: Advisory Panel; Applied Therapeutics Inc. N.E.Ibrahim: None. C.S.Lam: Other Relationship; Actelion, Alleviant Medical, Allysta Pharma, Amgen, AnaCardio, Applied Therapeutics, AstraZeneca, Bayer, Boehringer-Ingelheim, Boston Scientific, Cytokinetics, Darma Inc, EchoNous Inc, Eli Lilly, Impulse Dynamics, Intellia Therapeutics, Ionis Pharmaceutical, Janssen Research & Development LLC, Medscape/WebMD Global LLC, Merck, Novartis, Novo Nordisk, Prosciento Inc, Radcliffe Group Ltd, Recardio Inc, ReCor Medical, Roche Diagnostics, Sanofi, Siemens Healthcare Diagnostics, Us2.ai. R.Perfetti: None. J.Rosenstock: Advisory Panel; Applied Therapeutics Inc., Boehringer Ingelheim Inc., Eli Lilly and Company, Novo Nordisk, Oramed Pharmaceuticals, Sanofi, Zealand Pharma A/S, Intarcia Therapeutics, Inc., Hanmi Pharm. Co., Ltd., Research Support; Applied Therapeutics Inc., Boehringer Ingelheim Inc., Eli Lilly and Company, Merck & Co., Inc., Novartis, Novo Nordisk, Pfizer Inc., Sanofi, Intarcia Therapeutics, Inc. W.Tang: Consultant; Sequana Medical NV, Cardiol Therapeutics, Genomics plc, Zehna Therapeutics LLC, Renovacor, Boston Scientific Corporation, Kiniksa Pharmaceuticals Inc, WhiteSwell Inc, CardiaTec Biosciences Inc, Other Relationship; American Board of Internal Medicine, Springer Nature, Research Support; National Heart, Lung, and Blood Institute. A.Urbinati: None.

Relation of early-stage renal insufficiency and cardiac structure and function in a large population of asymptomatic Asians: a cross-sectional cohort analysis.

Few studies have addressed early-stage kidney disease and preclinical cardiac structural and functional abnormalities from a large-scale Asian population. Further, the extent to which measures of myocardial function and whether these associations may vary by testing various formulas of renal insufficiency remains largely unexplored. To explore the associations among renal function, proteinuria, and left ventricular (LV) structural and diastolic functional alterations. A cross-sectional, retrospective cohort study. Registered data from a cardiovascular health screening program at MacKay Memorial Hospital from June 2009 to December 2012. Asymptomatic individuals. Renal function was evaluated in terms of estimated glomerular filtration rate (eGFR) by both MDRD and CKD-EPI formulas and severity of proteinuria, which were further related to cardiac structure, diastolic function (including LV e' by tissue Doppler), and circulating N-terminal pro-brain natriuretic peptide (NT-proBNP) level. Among 4942 participants (65.8% men, mean age 49.4 ± 11.2 years), the mean CKD-EPI/MDRD eGFR was 90.6 ± 15.7 and 88.5 ± 16.9 ml/min/1.73m2, respectively. Lower eGFR, estimated either by the MDRD or CKD-EPI method, and higher proteinuria were significantly associated with lower LV e' and higher NT-proBNP (all p<0.05) even after adjusting for clinical covariates. In general, lower eGFR estimated by CKD-EPI and MDRD displayed similar impacts on worsening e' and NT-proBNP, rather than E/e', in multivariate models. Finally, lower LV e' or higher composite diastolic score, rather than E/e', demonstrated remarkable interaction with eGFR level estimated by either CKD-EPI or MDRD on circulating NT-proBNP level (p interaction <0.05). Proteinuria was estimated using a urine dipstick rather than more accurately by the urine protein-to-creatinine ratio. Also, pertaining drug history and clinical hard outcomes were lacking. Both clinical estimate of renal insufficiency by eGFR or proteinuria, even in a relatively early clinical stage, were tightly linked to impaired cardiac diastolic relaxation and circulating NT-proBNP level. Elevation of NT-proBNP with worsening renal function may be influenced by impaired myocardial relaxation.

Engineered cardiac tissue model of restrictive cardiomyopathy for drug discovery

Restrictive cardiomyopathy (RCM) is defined as increased myocardial stiffness and impaired diastolic relaxation leading to elevated ventricular filling pressures. Human variants in filamin C (FLNC) are linked to a variety of cardiomyopathies, and in this study, we investigate an in-frame deletion (c.7416_7418delGAA, p.Glu2472_Asn2473delinAsp) in a patient with RCM. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) with this variant display impaired relaxation and reduced calcium kinetics in 2D culture when compared with a CRISPR-Cas9-corrected isogenic control line. Similarly, mutant engineered cardiac tissues (ECTs) demonstrate increased passive tension and impaired relaxation velocity compared with isogenic controls. High-throughput small-molecule screening identifies phosphodiesterase 3 (PDE3) inhibition by trequinsin as a potential therapy to improve cardiomyocyte relaxation in this genotype. Together, these data demonstrate an engineered cardiac tissue model of RCM and establish the translational potential of this precision medicine approach to identify therapeutics targeting myocardial relaxation.

Effects of homoarginine supplementation on heart and skeletal muscle of rats with heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) is associated with left ventricular stiffness, impaired diastolic relaxation, and severe exercise intolerance. Decreased homoarginine (hArg) levels are an independent predictor of mortality in cardiovascular disease and correlate with impaired exercise performance. We recently reported alterations in arginine, hArg, and related amino acids in obese ZSF1 rats (O-ZSF1), with a HFpEF phenotype. Although low hArg is associated with diastolic dysfunction in humans, potential effects of hArg supplementation were not tested yet. At an age of 6weeks, 12 O-ZSF1 were randomized into two groups: (1) O-ZSF1 rats supplemented with hArg in their drinking water (sO-ZSF1) or (2) O-ZSF1 rats receiving no hArg supplementation (O-ZSF1). At an age of 32weeks, effects of primary prevention by hArg supplementation on echocardiographic, histological, and functional parameters of heart and skeletal muscle were determined. Lean ZSF1 rats (L-ZSF1) served as controls. hArg supplementation did not prevent impairment of diastolic relaxation (E/e': O-ZSF1 21±3 vs. sO-ZSF1 22±3, P=0.954, L-ZSF1 18±5) but resulted in more cardiac fibrosis (histological collagen staining: +57% in sO-ZSF1 vs. O-ZSF1, P=0.027) and increased collagen gene expression (Col1a1: +48% in sO-ZSF1 vs. O-ZSF1, P=0.026). In contrary, right ventricular function was preserved by hArg supplementation (TAPSE (mm): O-ZSF1 1.2±0.3 vs. sO-ZSF1 1.7±0.3, P=0.020, L-ZSF1 1.8±0.4). Musculus soleus maximal specific muscle force (N/cm2 ) in O-ZSF1 (30.4±0.8) and sO-ZSF1 (31.9±0.9) was comparable but significantly reduced compared with L-ZSF1 (36.4±0.7; both P<0.05). Maximal absolute muscle force (g) (O-ZSF1: 177.6±7.8, sO-ZSF1: 187.8±5.0, L-ZSF1: 181.5±7.9, all P>0.05) and cross-sectional fibre area (arbitrary units) (O-ZSF1: 1697±57, sO-ZSF1: 1965±121, L-ZSF1: 1691±104, all P>0.05) were not altered. Preservation of physiological hArg level in HFpEF may not be suited to prevent alterations in left ventricular and skeletal muscle function and structure. However, hArg supplementation may be beneficial for right ventricular function especially in pulmonary hypertension in HFpEF. We may speculate that clinically observed decreased hArg level are not the cause but the consequence of a yet unrecognized pathomechanism that underpins HFpEF.

Abstract P274: Inhibition Of Abnormal Exosome Release Prevents Excessive Aortic Stiffness And Relaxation Dysfunction In Diet-induced Obesity

Interactions between over-nutrition and abnormal exosome release impact insulin sensitivity and the development of cardiovascular disease (CVD). Recent data have shown that exosomes can be released from various cell types, including adipocytes and vascular cells, and that they exist in body fluids and tissues functioning as mediators of cell-cell communication. However, the specific role of exosomes in diet-induced excessive vascular stiffness and hypertension has not been explored. Accordingly, we hypothesized that abnormal release of exosomes contributes to western diet (WD)- induced aortic stiffening and impaired vascular diastolic relaxation. We further posited that GW4869, an antagonist of neutral sphingomyelinase 2 (nSMase2) which promotes exosome production and release, would prevent WD-induced aortic stiffening and impaired vascular relaxation. Six week-old female C57BL/6L mice were fed a mouse chow (CD) or WD containing excess fat (46%) and fructose (17.5%) for 16 weeks with or without GW4849. To this point, 200 μl of 0.3 mg/mL GW4869 in 0.9% normal saline (60 μg/mouse; 2-2.5 μg/g body weight) was injected intraperitoneally every 48 hours for 12 weeks. 16 weeks of WD induced an increase of aortic stiffness as examined by pulse wave velocity (PWV) and impaired the aortic vasodilation responses to acetylcholine (Ach) and sodium nitroprusside (SNP) (10 -9 -10 -4 mol/L). However, GW4869 treatment prevented the WD-induced excessive aortic stiffness, as well as impairment of endothelium dependent/independent vascular relaxation. There were no significant differences in blood pressure between each group examined by tail cuff blood pressure measurement. These findings support the hypothesis that abnormal release of exosomes play an important role in WD-induced excessive aortic stiffness, impaired vascular relaxation and CVD in diet-induced obesity.

Epidermal growth factor receptor-dependent maintenance of cardiac contractility.

Epidermal growth factor receptor (EGFR) is essential to the development of multiple tissues and organs and is a target of cancer therapeutics. Due to the embryonic lethality of global EGFR deletion and conflicting reports of cardiac-overexpressed EGFR mutants, its specific impact on the adult heart, normally or in response to chronic stress, has not been established. Using complimentary genetic strategies to modulate cardiomyocyte-specific EGFR expression, we aim to define its role in the regulation of cardiac function and remodelling. A floxed EGFR mouse model with α-myosin heavy chain-Cre-mediated cardiomyocyte-specific EGFR downregulation (CM-EGFR-KD mice) developed contractile dysfunction by 9 weeks of age, marked by impaired diastolic relaxation, as monitored via echocardiographic, haemodynamic, and isolated cardiomyocyte contractility analyses. This contractile defect was maintained over time without overt cardiac remodelling until 10 months of age, after which the mice ultimately developed severe heart failure and reduced lifespan. Acute downregulation of EGFR in adult floxed EGFR mice with adeno-associated virus 9 (AAV9)-encoded Cre with a cardiac troponin T promoter (AAV9-cTnT-Cre) recapitulated the CM-EGFR-KD phenotype, while AAV9-cTnT-EGFR treatment of adult CM-EGFR-KD mice rescued the phenotype. Notably, chronic administration of the β-adrenergic receptor agonist isoproterenol effectively and reversibly compensated for the contractile dysfunction in the absence of cardiomyocyte hypertrophy in CM-EGFR-KD mice. Mechanistically, EGFR downregulation reduced the expression of protein phosphatase 2A regulatory subunit Ppp2r3a/PR72, which was associated with decreased phosphorylation of phospholamban and Ca2+ clearance, and whose re-expression via AAV9-cTnT-PR72 rescued the CM-EGFR-KD phenotype. Altogether, our study highlights a previously unrecognized role for EGFR in maintaining contractile homeostasis under physiologic conditions in the adult heart via regulation of PR72 expression.

Cirrhotic Cardiomyopathy: The Interplay Between Liver and Cardiac Muscle. How Does the Cardiovascular System React When the Liver is Diseased?

It is widely known that liver cirrhosis, regardless of the etiologies is accompanied by severe hemodynamic changes. The principal pathophysiological mechanisms are the hyperdynamic circulation with increased cardiac output, heart rate along with reduced systemic vascular resistance. Thus, counteractive mechanisms may develop that eventually lead to systolic as well as diastolic dysfunction and rhythm disturbances, in order to keep a steady homeostasis in the human body.Literally, blunted contractile responsiveness to physical or pharmacological stress, impaired diastolic relaxation and electrophysiological changes, primarily QT interval prolongation, do occur progressively in a cirrhotic patient with no known preexisting cardiac disease. This condition is identified as cirrhotic cardiomyopathy (CCM), an entity different from that seen in alcoholic cardiac muscle disease.For the past decades, clinicians did study and attempt to understand the pathophysiology and clinical significance of this process. Indeed, various factors have been identified acting at the molecular and cellular level.Electrocardiography, echocardiography and various serum biomarkers are the main tools that help healthcare practitioners to point to the correct diagnosis.Noteworthy, the subjects that suffer from cirrhotic cardiomyopathy may progress to heart failure during invasive procedures such as surgery, insertion of a transjugular intrahepatic portosystemic shunting (TIPS) and liver transplantation. Besides, several studies have illustrated that CCM is a contributing factor, or even a precipitant, of hepatorenal syndrome (HRS), a conceivable reversible kidney failure in patients with liver cirrhosis and ascites.The treatment is the same as it is in the patients with liver cirrhosis and heart failure and there is no particular treatment for cirrhotic cardiomyopathy. Hence, it is of utmost importance to clearly comprehend the pathophysiology of this disease in order to design more accurate diagnostic tools and definitive treatments in a way to prevent the complications of cirrhosis and overt heart failure.The objective of this review is to describe in a comprehensive way the pathological alterations that occur in the cardiovascular system of cirrhotic patients. It will also point the limitations that remain in the diagnosis and treatment strategies and more importantly, this review will alert the clinicians in the modern era to further observe and record additional pathological changes in this subset of patients.

Echocardiographic parameters according to insulin dose in young patients affected by type 1 diabetes.

Insulin dose has been found to associate to several cardiometabolic risk factors in type 1 diabetes. Changes over time in body weight and composition may partly explain this association. However, no data are available on the relationship between insulin dose and echocardiographic parameters of both systolic and diastolic function in type 1 diabetes. Therefore, the aim of the present study was to examine systolic and diastolic echocardiographic parameters in relation to insulin dose in young patients with type 1 diabetes. The study was carried out on 93 consecutive outpatients with type 1 diabetes with a mean age of 32.8 ± 9.8 years. All patients were examined with a transthoracic echocardiography. Clinical and laboratory data were collected. The median value of daily insulin dose was used to categorized patients in two groups: high and low insulin dose group. Patients belonging to the high insulin dose group showed higher levels of cardiometabolic risk factors such as BMI, triglycerides and TG/HDL cholesterol ratio. Indexes of both systolic and diastolic function were similar in both groups except isovolumetric relaxation time (IVRT), that was significantly prolonged in patients of the high insulin group (94.4 ± 15.0 vs 86.7 ± 13.1 ms, p = 0.008). In the multivariate regression analysis, insulin dose was positively and significantly associated with IVRT. In this study we report an association between insulin dose and impaired active diastolic myocardial relaxation. Future studies are needed to further explore this observation.

Cirrhotic Cardiomyopathy-A Veiled Threat.

Cirrhotic cardiomyopathy (CCM) is defined as cardiac dysfunction in patients with liver cirrhosis without preexisting cardiac disease. According to the definition established by the World Congress of Gasteroenterology in 2005, the diagnosis of CCM includes criteria reflecting systolic dysfunction, impaired diastolic relaxation, and electrophysiological disturbances. Because of minimal or even absent clinical symptoms and echocardiographic signs at rest according to the 2005 criteria, CCM diagnosis is often missed or delayed in most clinically stable cirrhotic patients. However, cardiac dysfunction progresses in time and contributes to the pathogenesis of hepatorenal syndrome and increased morbidity and mortality after liver transplantation, surgery, or other invasive procedures in cirrhotic patients. Therefore, a comprehensive cardiovascular assessment using newer techniques for echocardiographic evaluation of systolic and diastolic function, allowing the diagnosis of CCM in the early stage of subclinical cardiovascular dysfunction, should be included in the screening process of liver transplant candidates and patients with cirrhosis in general. The present review aims to summarize the most important pathophysiological aspects of CCM, the usefulness of contemporary cardiovascular imaging techniques and parameters in the diagnosis of CCM, the current therapeutic options, and the importance of early diagnosis of cardiovascular impairment in cirrhotic patients.

Distinct features of calcium handling and β-adrenergic sensitivity in heart failure with preserved versus reduced ejection fraction.

Key points Heart failure (HF), the leading cause of death in developed countries, occurs in the setting of reduced (HFrEF) or preserved (HFpEF) ejection fraction. Unlike HFrEF, there are no effective treatments for HFpEF, which accounts for ∼50% of heart failure.Abnormal intracellular calcium dynamics in cardiomyocytes have major implications for contractility and rhythm, but compared to HFrEF, very little is known about calcium cycling in HFpEF.We used rat models of HFpEF and HFrEF to reveal distinct differences in intracellular calcium regulation and excitation‐contraction (EC) coupling.While HFrEF is characterized by defective EC coupling at baseline, HFpEF exhibits enhanced coupling fidelity, further aggravated by a reduction in β‐adrenergic sensitivity.These differences in EC coupling and β‐adrenergic sensitivity may help explain why therapies that work in HFrEF are ineffective in HFpEF. Heart failure with reduced or preserved ejection fraction (respectively, HFrEF and HFpEF) is the leading cause of death in developed countries. Although numerous therapies improve outcomes in HFrEF, there are no effective treatments for HFpEF. We studied phenotypically verified rat models of HFrEF and HFpEF to compare excitation‐contraction (EC) coupling and protein expression in these two forms of heart failure. Dahl salt‐sensitive rats were fed a high‐salt diet (8% NaCl) from 7 weeks of age to induce HFpEF. Impaired diastolic relaxation and preserved ejection fraction were confirmed in each animal echocardiographically, and clinical signs of heart failure were documented. To generate HFrEF, Sprague‐Dawley (SD) rats underwent permanent left anterior descending coronary artery ligation which, 8–10 weeks later, led to systolic dysfunction (verified echocardiographically) and clinical signs of heart failure. Calcium (Ca2+) transients were measured in isolated cardiomyocytes under field stimulation or patch clamp. Ultra‐high‐speed laser scanning confocal imaging captured Ca2+ sparks evoked by voltage steps. Western blotting and PCR were used to assay changes in EC coupling protein and RNA expression. Cardiomyocytes from rats with HFrEF exhibited impaired EC coupling, including decreased Ca2+ transient (CaT) amplitude and defective couplon recruitment, associated with transverse (t)‐tubule disruption. In stark contrast, HFpEF cardiomyocytes showed saturated EC coupling (increased I Ca, high probability of couplon recruitment with greater Ca2+ release synchrony, increased CaT) and preserved t‐tubule integrity. β‐Adrenergic stimulation of HFpEF myocytes with isoprenaline (isoproterenol) failed to elicit robust increases in I Ca or CaT and relaxation kinetics. Fundamental differences in EC coupling distinguish HFrEF from HFpEF.

Endothelial sodium channel activation promotes cardiac stiffness and diastolic dysfunction in Western diet fed female mice

ObjectiveObesity is associated with myocardial fibrosis and impaired diastolic relaxation, abnormalities that are especially prevalent in women. Normal coronary vascular endothelial function is integral in mediating diastolic relaxation, and recent work suggests increased activation of the endothelial cell (EC) mineralocorticoid receptor (ECMR) is associated with impaired diastolic relaxation. As the endothelial Na+ channel (EnNaC) is a downstream target of the ECMR, we sought to determine whether EC-specific deletion of the critical alpha subunit, αEnNaC, would prevent diet induced-impairment of diastolic relaxation in female mice. Methods and materialsFemale αEnNaC KO mice and littermate controls were fed a Western diet (WD) high in fat (46%), fructose corn syrup (17.5%) and sucrose (17.5%) for 12–16 weeks. Measurements were conducted for in vivo cardiac function, in vitro cardiomyocyte stiffness and EnNaC activity in primary cultured ECs. Additional biochemical studies examined indicators of oxidative stress, including aspects of antioxidant Nrf2 signaling, in cardiac tissue. ResultsDeletion of αEnNaC in female mice fed a WD significantly attenuated WD mediated impairment in diastolic relaxation. Improved cardiac relaxation was accompanied by decreased EnNaC-mediated Na+ currents in ECs and reduced myocardial oxidative stress. Further, deletion of αEnNaC prevented WD-mediated increases in isolated cardiomyocyte stiffness. ConclusionCollectively, these findings support the notion that WD feeding in female mice promotes activation of EnNaC in the vasculature leading to increased cardiomyocyte stiffness and diastolic dysfunction.

P873 A rare and potentially treatable cause of left ventricular hypertrophy

Abstract Introduction A 67-year-old man was referred for care of "asymptomatic hypertrophic cardiomyopathy". He did not have hypertension. No significant positive family history could be elicited. Electrocardiogram showed sinus rhythm with voltage criteria of left ventricular hypertrophy (LVH). Outside Transthoracic Echocardiogram (TTE) reported normal ejection fraction with asymmetric septal hypertrophy without outflow obstruction. He was put on observation for few years and was not any treatment. On first encounter in our clinic, physical examination including skin and eye assessment, and laboratory tests including renal function were unremarkable. Procedure TTE was repeated in our clinic showing normal left ventricular size with ejection fraction 55%, and impaired diastolic relaxation. There was asymmetric septal hypertrophy with septal thickness 2.1 cm (Figure A). There was mild systolic anterior motion of mitral apparatus and mild mitral regurgitation, without resting or Valsalva provoked outflow obstruction. Global longitudinal strain was -7.7% with most prominent abnormalities seen at apex, mid to basal anteroseptal and anterior wall (Figure B). Further assessment by Cardiac MRI showed similar asymmetric septal wall thickening. Late gandolinium enhancement study demonstrated patchy fluffy hyperenhancement of the mid wall of the basal to mid anteroseptal segment, and mid to apical anterior segment, suggestive of myocardial fibrosis (Figure C1 and C2). Dried spot blood was sent to Taiwan for enzyme study which revealed partial acid alpha-galactosidase A deficiency. Further genetic study detected a mutation of Hemizygous NM_000169.2(GLA):c.640-801[G &amp;gt; A] at intron 4. Finally endomyocardial biopsy was done which confirmed the cardiac involvement of Fabry disease (Figure D, myelin body shown under electron microscopy). This gentleman was referred for consideration of Enzyme Replacement Therapy (ERT). Discussion Fabry disease is an X-linked glycolipid storage disease with accumulation of globotriaosylceramide in lysosomes in multiple cell types throughout the body leading to various organ involvement. Cardiac manifestations include unexplained LVH, valvular regurgitation, conduction abnormalities etc. It occurs in up to 0.3-5% of patients with hypertrophic cardiomyopathy. Fabry disease should be considered as a differential diagnosis in all men with sporadic or non-autosomal dominant transmission of unexplained LVH, since treatment with ERT is available which may reduce LVH and improve myocardial function, although any impact on long term outcome has not yet been established. Conclusion This case illustrated a rare but potentially treatable cause of hypertrophic cardiomyopathy. Myocardial strain imaging should be integrated in routine TTE study for assessment of unexplained left ventricular hypertrophy. Multi-modality imaging and multi-specialty approach help in identifying patients of cardiac variant of Fabry disease who may benefit from ERT. Abstract P873 Figure.

Abstract 009: Endothelial Epithelial Sodium Channel Promotes Intrinsic Cardiomyocyte Stiffness and Diastolic Dysfunction in Response to a Diet Induced Obesity in Female Mice

Obesity is associated with a metabolic cardiomyopathy characterized by diastolic dysfunction with preserved systolic function. Although premenopausal non-obese women show relative protection against development of metabolic cardiomyopathy and cardiovascular disease compared to men, this relationship is lost in obese women. Diastolic dysfunction in such cardiomyopathy is caused not only by extrinsic extracellular remodeling and interstitial fibrosis but also through alterations in intrinsic stiffness of cardiomyocytes. One mechanism by which intrinsic cardiomyocyte stiffness is increased in obesity is decreased coronary endothelial cell production of nitric oxide. We have described a clinically relevant diet induced obesity murine model that exhibits increased vascular stiffness associated with cardiac dysfunction. In this model, female mice have high plasma aldosterone levels and increased mineralocorticoid receptor (MR) expression in both the vasculature and heart. One of the mechanisms by which MR activation promotes endothelial stiffness is through increased expression and activation of epithelial sodium channel (ENaC) in ECs (EnNaC). In this study, we tested the hypothesis that specific deletion of EnNaC ameliorates increases in endothelial stiffness and decreases diastolic dysfunction occurring during diet induced obesity (DIO) in female mice. To produce cell specific deletion of the EnNaC gene,”floxed” EnNaC mice were serially crossed with Tie 2-Cre transgene mice. This resulted in marked suppression of EnNaC expression in ECs. Female KO mice and littermate controls were fed a diet high in fat (46%) and fructose (17.5%) for 12 to 16 weeks. Compared to mice fed a control diet (CD), whole cell sodium currents in pulmonary ECs and aortic EC stiffness were significantly increased in DIO mice and this was prevented in EnNaC KO mice with DIO. Moreover, deletion of EnNaC also prevented DIO increases in stiffness of isolated cardiomyocytes (WD, 7.43 ± 1.21 kPA, WD-KO, 3.47 ± 0.14 kPA) as well as normalizing impaired diastolic relaxation. Collectively, these findings support the notion that DIO promotes coronary ECMR mediated activation of EnNaC and associated increases in intrinsic cardiomyocyte stiffness and diastolic dysfunction.

Carvedilol Combined With Ivabradine Improves Left Ventricular Diastolic Dysfunction, Clinical Progression, and Survival in Cirrhosis.

Left ventricular diastolic dysfunction (LVDD) refers to impaired cardiac diastolic relaxation and may be improved by targeted heart rate reduction (THR). The authors evaluated whether a combination of carvedilol and ivabradine, an If channel blocker that reduces heart rate without affecting blood pressure, could improve LVDD and outcomes in cirrhosis. THR was defined as heart rate reduction to 55 to 65 beats per minute. Of 260 patients with cirrhosis, 189 (72%) with LVDD were randomized to THR [group (Gr.)A; n=94; carvedilol±ivabradine)] or standard care (Gr.B; n=95; no β-blockers) and followed for 12 months. In Gr.A, THR was achieved at 4 weeks in 88 (93%) patients (responders, R): 48 (61.5%) with carvedilol alone and 40 (86.9%) of 46 patients with additional ivabradine. In Gr.A, LVDD reversed in 16 (20.5%) and improved from grade 2 to 1 in 34 (35.4%)], whereas in Gr.B, it progressed from grade 1 to 2 in 10 (10.5%) patients. At 12 months, 21 (11.1%) patients died, 6 (14%) in Gr.A and 15 (18%) in Gr.B (P=0.240), but no mortality was seen in those who had persistent THR at 1 year (n=78; P=0.000). In multivariate analysis, model for end-stage liver disease [hazard ratio (HR), 1.52; 95% confidence interval (CI), 1.22-2.75; P=0.034] and E-wave transmitral/early diastolic mitral annular velocity (HR, 1.28; 95% CI, 1.23-2.42; P=0.048) predicted 1-year mortality. Nonresponders had an increased mortality risk (HR, 1.3; 95% CI, 1.2-1.8; P=0.046) independent of age, gender, and baseline model for end-stage liver disease. Levels of norepinephrine, N terminal brain natriuretic peptide, plasma renin activity, and aldosterone were reduced (P<0.01) in responders. More patients in Gr.B developed acute kidney injury (odds ratio, 4.2; 95% CI, 2.8-10.5; P=0.027) and encephalopathy (odds ratio, 6.6; 95% CI, 1.9-9.7; P=0.040). Ivabradine combined with carvedilol improves LVDD, achieves THR more often and reduces risk of encephalopathy, acute kidney injury with improved survival in patients with cirrhosis.

Cardiomyocyte‐Specific EGFR Deletion Differentially Alters Cardiac Contractility and Remodeling

Epidermal Growth Factor Receptor (EGFR), a member of the Erbb receptor tyrosine kinase family, is essential to the development of multiple tissues and organs. Due to the embryonic lethality of global EGFR deletion, the impact of EGFR signaling in the adult heart, normally or in response to pathological stimuli, has not been well‐explored. Using mice with floxed EGFR alleles crossed with αMHC‐Cre mice, we have generated a cardiomyocyte‐specific constitutive EGFR knockout mouse model (CM‐EGFR‐KO) to address its role in the heart. Compared to their wild‐type (WT) littermate controls, CM‐EGFR‐KO mice displayed age‐related development of cardiac contractile dysfunction, marked by impaired diastolic relaxation and Ca2+ handling at the individual myocyte level, as monitored via echocardiographic, hemodynamic, myocyte contractility and Ca2+ transient analyses. RNASeq analysis of CM‐EGFR‐KO versus WT littermate left ventricular samples revealed temporally‐dependent alterations in the expression of a number of myofilament, Ca2+ handling and fetal genes. The contractile defect initially occurs between 7 and 9 weeks of age and is maintained over time without overt cardiac hypertrophic or fibrotic remodeling until 10 months of age, by which time the mice ultimately succumb to severe heart failure and reduced lifespan. Chronic administration of the β‐adrenergic receptor (βAR) agonist isoproterenol effectively compensated for the contractile dysfunction in CM‐EGFR‐KO mice, an effect that was reversible upon cessation of infusion. Notably, βAR‐mediated cardiomyocyte hypertrophy was attenuated in CM‐EGFR‐KO mice compared to WT littermate controls. Treatment of 16 week‐old CM‐EGFR‐KO mice with AAV9‐cTnT‐EGFR permanently rescued cardiomyocyte‐specific EGFR expression and contractile function, suggesting that the contractile dysfunction phenotype observed in these mice is not secondary to aberrant cardiac development, but is specific to EGFR‐dependent regulation of contractile signaling.Support or Funding InformationNIH grant HL105414 to DGTThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sleeve gastrectomy in obese Wistar rats improves diastolic function and promotes cardiac recovery independent of weight loss

BackgroundHeart failure with preserved ejection fraction is the most common cause of heart failure and is characterized by impaired diastolic relaxation. Bariatric surgery significantly improves diastolic relaxation, but a mechanism beyond weight loss remains unknown. ObjectivesWe tested the hypothesis that a sleeve gastrectomy (SG) will improve diastolic dysfunction independent of weight loss due to postoperative alterations in the enterocardiac axis. SettingUniversity research laboratory. MethodsMale Wistar rats were fed a high-fat diet (HFD) or low-fat diet (LFD) for 10 weeks and then divided into SG-HFD, pair-fed sham HFD, ad-lib sham HFD, or ad-lib sham LFD groups (n = 9–14 per group). At least 2 months postoperatively, cardiac function, meal tolerance, glucose tolerance, and cardiac gene expression were compared between groups. ResultsOnly the SG cohort showed significant improvements in postoperative diastolic relaxation (isovolumetric relaxation time pre-SG: 14.7 ± 2.3 msec, post-SG: 11.2 ± 1.8 msec, P < .001). SG significantly increased active glucagon-like peptide-1 (P = .03). Compared to pair-fed sham HFD rats, SG-HFD rats had significantly altered mRNA cardiac gene expression, including sarco/endoplasmic reticulum Ca2+-ATPase 2 a (SERCA2 a) (P < .001). ConclusionsSG improves diastolic function independent of weight loss in a rat model of obesity with beneficial alterations in cardiac gene expression of multiple known targets related to cardiac failure, including SERCA2 a. These data support that a greater curve gastrectomy induces beneficial intracellular cardiac signaling for diastolic function mediated by the enterocardiac axis that is independent of weight loss. These findings could translate to offering metabolic surgery to patients with heart failure with preserved ejection fraction.

Istaroxime improves diabetic diastolic dysfunction through SERCA stimulation

Calcium handling is generally impaired in heart failure (HF). Mechanisms that can restore cardiac relaxation improving cellular Ca2 + cycling, represent a promising therapeutic approach for HF. Istaroxime is a Na-K ATPase (NKA) inhibitor with the property of accelerating Ca2 + re-uptake into sarcoplasmic reticulum (SR) through the SR Ca2 + pump (SERCA) stimulation by displacing the interaction between SERCA and its inhibitor, phospholamban (PLB). To characterize Istaroxime effects in a model of mild diabetes (type 1) with diastolic dysfunction and preserved global systolic function. Istaroxime was tested at a concentration mostly unaffecting NKA to isolate its effects dependent on SERCA only. Streptozotocin (STZ)-treated rats were evaluated at 9 weeks after STZ injection in comparison to control (CTR) ones. STZ-induced changes were evaluated in vivo (echocardiography), in isolated left ventricular myocytes and in SERCA2a-enriched microsomes. SERCA and PLB protein levels were measured by western blot and SERCA activity as 32P hydrolysis. Action potential rate-dependency and intracellular Ca2 + handling were evaluated in patch clamped or field-stimulated (2 Hz) cells. STZ-induced cardiomyopathy was characterized by impaired diastolic relaxation which was associated to reduced SERCA protein level and activity at the cellular level. Moreover, the monomeric PLB/SERCA ratio was increased. In STZ group, action potentials (AP) were significantly prolonged at each cycle length; Ca2 + transients were characterized by slower decay, delayed onset and increased diastolic Ca2 + . Istaroxime at a concentration of 100 nM significantly stimulated SERCA activity and SR Ca re-uptake after caffeine depletion in STZ group only. Moreover, Istaroxime reduced STZ-induced diastolic Ca2 + enhancement but not affected AP prolongation. SERCA stimulation can be considered a promising therapeutic approach for diastolic dysfunction treatment.

42. A study of cardiovascular dysfunction in cirrhosis of liver & its correlation with the severity of cirrhosis in Eastern India

Background and Aims: Cirrhosis of liver is associated with subclinical cardiovascular (CVS) dysfunction characterized by diminished systolic responsiveness to stress stimuli, impaired diastolic relaxation, electrophysiological abnormalities, and enlargement and hypertrophy of cardiac chambers, all in the absence of known cardiac disease. However, evidence suggests that patients with cirrhosis display primarily left ventricular diastolic dysfunction (LVDD) with normal systolic function at rest. We aim to evaluate cardiovascular dysfunction in patients of cirrhosis and its correlation with severity of liver cirrhosis as by Child pugh turcotte (CPT) and MELD scoring system and circulatory function. Methods: Prospective observational study, where CVS evaluation of 60 patients (20 patients each in CHILD A, B and C) was done by both conventional 2D and tissue Doppler echocardiography. Statistical analysis was done using SPSS 20 software and p < 0.05 considered significant. Results: GR1, GR2 And GR3 LVDD were present in 23.33%, 43.33% and 20% of the patients respectively. Patients with LVDD had significantly higher (p < 0.05) left atrial diameter (LAD), E wave transmitral /early diastolic mitral annular velocity (E/e ratio), pulmonary arterial systolic pressure (PASP), natriuretic peptide level, CTP and MELD score. GR2 and GR3 LVDD were associated with ascites and increased plasma renin activity compared to GR 1 LVDD and without LVDD suggestive of direct correlation between LVDD and circulatory dysfunction. Heart rate and systolic function were normal in all cases. Survival was not different according to the degree of LVDD (p = 0.739) in 3 groups of patients. Conclusions: LVDD occurs simultaneously with other changes in cardiac structure and function in cirrhosis and is associated with circulatory dysfunction. Both conventional 2D Echocardiography and tissue Doppler imaging (TDI) are non-invasive, real-time, rapid imaging technology with a high accuracy for diagnosing CVS abnormalities, such as those indicative of cirrhotic cardiomyopathy. The authors have none to declare.

Abstract 21224: Coronary Microvascular Dysfunction in Patients With Normal and Abnormal Diastolic Function in Patients With Heart Failure and Preserved Ejection Fraction

Introduction: A potential mechanism for impaired diastolic relaxation and stiffness in patients with heart failure with preserved ejection fraction (HFpEF) is the presence of coronary microvascular dysfunction (CMD). Invasive studies have demonstrated that HFpEF can be present in patients regardless of the presence or absence of echocardiographic diastolic dysfunction. Hypothesis: We hypothesize that CMD is common in HFpEF with normal and abnormal echocardiographic diastolic function. Methods: In a prospective study of HFpEF patients (n=30), clinical, echocardiographic, hemodynamic, and coronary physiology (CP) data were evaluated. CP parameters measured included coronary flow reserve (CFR) and index of microvascular resistance (IMR). Echocardiographic diastolic dysfunction (DD) was graded according to current ASE guidelines. Baseline clinical, echocardiographic, hemodynamic, and CP data were compared between grade 0 DD (n=10) and grade 1-3 DD (n=11), excluding patients with indeterminate DD grade (n=10). Results: Age, gender, and comorbidities were similar in the grade 0 compared to grade 1-3 DD groups. Median BNP was higher in the grade 1-3 compared to the grade 0 DD group (462 vs. 98, p=0.012). All DD and strain measurements were significantly abnormal in the grade 1-3 compared to grade 0 DD groups, as were mean pulmonary artery, and left-sided filling pressures. Mean IMR was elevated and similar in patients with and without DD (30.5 vs. 27.9, p=0.58), however mean CFR was abnormal and lower in the grade 1-3 compared to grade 0 DD groups (2.05 vs. 3.30, p=0.053). Conclusions: Although BNP, LV and left atrial strain, and LV filling pressures were higher in HFpEF patients with abnormal diastolic function compared to "normal" diastolic function, we found that elevated microvascular resistance is present in patients with HFpEF and "normal" diastolic function, but these patients have relatively preserved CFR.