Left Ventricular Dilatation Research Articles

Abnormal circadian rhythms exacerbate dilated cardiomyopathy by reducing the ventricular mechanical strength.

Dilated cardiomyopathy (DCM) has etiological and pathophysiological heterogeneity. Abnormal circadian rhythm (ACR) is related to the development of DCM in animal models, but exploration based on clinical samples is lacking. Sleep apnea (SA) is the most common disease related to ACR, and we chose SA as the study object to explore ACR-DCM. We included a derivation cohort (n =105) and a validation cohort (n = 65). DCM patients were divided into SA and without SA group. RT-qPCR was used to determine the change of rhythm gene expression pattern of heart samples from different timepoints. We used single-nucleus RNA sequencing (snRNA-seq) to explore the abnormal transcriptional patterns in the ACR group, and we verified the findings by pathological staining, atomic force microscopy (AFM), and Rev-erbα/β knockout (KO) mice analysis. DCM patients with SA showed decreased amplitude of rhythm gene expression. SA group showed more severe dilation of left heart chambers. From snRNA-seq, ACR-DCM lost the morning transcriptional patterns, detailly, actin cytoskeleton organization of cardiomyocytes (CMs) disrupted and hypertrophy aggravated, and the proportion of activated fibroblasts (Fibs) decreased with the reduction of fibrotic area ratio. The results of pathological staining, mechanical experiments, and transcriptional feature of Rev-erbα/β KO mice supported the above findings. Compared with the non-SA group, left ventricular (LV) wall dilation was more severe and the structural strength was lower in DCM patients with SA, and phenotypic changes in CM and Fib were involved in this process. ACR-DCM was histopathologically characterized by a structurally weak ventricular wall.

The role of body composition in left ventricular remodeling, reverse remodeling, and clinical outcomes for heart failure with mildly reduced ejection fraction: more knowledge to the “obesity paradox”

BackgroundAlthough the “obesity paradox” is comprehensively elucidated in heart failure (HF) with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF), the role of body composition in left ventricular (LV) remodeling, LV reverse remodeling (LVRR), and clinical outcomes is still unclear for HF with mildly reduced ejection fraction (HFmrEF).MethodsOur study is a single-centre, prospective, and echocardiography-based study. Consecutive HFmrEF patients, defined as HF patients with a left ventricular ejection fraction (LVEF) between 40 and 49%, between January 2016 to December 2021 were included. Echocardiography was re-examined at 3-, 6-, and 12-month follow-up to assess the LVRR dynamically. Body mass index (BMI), fat mass, fat-free mass, percent body fat (PBF), CUN-BAE index, and lean mass index (LMI) were adopted as anthropometric parameters in our study to assess body composition. The primary outcome was LVRR, defined as: (1) a reduction higher than 10% in LV end-diastolic diameter index (LVEDDI), or a LVEDDI < 33 mm/m2, (2) an absolute increase of LVEF higher than 10 points compared with baseline echocardiogram, or a follow-up LVEF ≥50%. The secondary outcome was a composite of re-hospitalization for HF or cardiovascular death.ResultsA total of 240 HFmrEF patients were enrolled in our formal analysis. After 1-year follow-up based on echocardiography, 113 (47.1%) patients developed LVRR. Patients with LVRR had higher fat mass (21.7 kg vs. 19.3 kg, P = 0.034) and PBF (28.7% vs. 26.6%, P = 0.047) compared with those without. The negative correlation between anthropometric parameters and baseline LVEDDI was significant (all P < 0.05). HFmrEF patients with higher BMI, fat mass, PBF, CUN-BAE index, and LMI had more pronounced and persistent increase of LVEF and decline in LV mass index (LVMI). Univariable Cox regression analysis revealed that higher BMI (HR 1.042, 95% CI 1.002–1.083, P = 0.037) and fat mass (HR 1.019, 95% CI 1.002–1.036, P = 0.026) were each significantly associated with higher cumulative incidence of LVRR for HFmrEF patients, while this relationship vanished in the adjusted model. Mediation analysis indicated that the association between BMI and fat mass with LVRR was fully mediated by baseline LV dilation. Furthermore, higher fat mass (aHR 0.957, 95% CI 0.917–0.999, P = 0.049) and PBF (aHR 0.963, 95% CI 0.924–0.976, P = 0.043) was independently associated with lower risk of adverse clinical events.ConclusionsBody composition played an important role in the LVRR and clinical outcomes for HFmrEF. For HFmrEF patients, BMI and fat mass was positively associated with the cumulative incidence of LVRR, while higher fat mass and PBF predicted lower risk of adverse clinical events but not LMI.Graphical abstract

Iron Overload Cardiomyopathy

Iron overload cardiomyopathy is a condition of excessive iron accumulation in cardiomyocytes due to abnormal iron absorption or repeated blood transfusion. In the early stages, the patient may be asymptomatic with good ventricular systolic function. Iron deposit in ventricular cause dyspnea on effort due to left ventricular systolic dysfunction then in atrial cause atrioventricular block and supraventricular arrhythmic. For severe symptom due to dilated cardiomyopathy is characterized by left ventricular dilatation and risk of sudden cardiac death. Diagnosis of iron overload cardiomyopathy can be made if there is evidence of heart disease, the presence of iron overload (serum ferritin &gt; 300 ng/mL and transferrin saturation &gt; 55%) and cardiac siderosis with cardiac MRI T2 * &lt; 20 ms as gold standard. Patient management involves lowering systemic iron levels and preventing iron entry into cardiomyocytes. Therapy with phlebotomy or iron chelation as indicated. Administration of calcium channel blockers and resveratrol antioxidant therapy may be considered to reduce morbidity and mortality due to cardiac siderosis.

Sex-related disparities in aortic stenosis from disease awareness to treatment: a state-of-the-art review.

This state-of-the-art review aimed to synthesize evidence from various sex-stratified studies on aortic stenosis (AS), focusing on the difference in clinical presentation, anatomical characteristics, pathophysiology, and management of AS. In comparison to men, women with AS are present at later stages, are older, more symptomatic, frailer, and exhibit higher operative risk [Society of Thoracic Surgeons (STS) score]. Women tend to have smaller aortic valve (AV) areas and left ventricular (LV) outflow tract, leading to lower stroke volumes (SVs) than men and have a higher prevalence of paradoxical, low-flow, low-gradient AS. In women, chronic pressure overload due to AS results in concentric LV remodelling and hypertrophy, characterized by reduced LV cavities, higher filling pressures, lower wall stress, and more diastolic dysfunction. Conversely, men exhibit more dilated eccentric LV remodelling and hypertrophy. AVs in women are less calcified but more fibrotic. Moreover, women are often underdiagnosed, have severity underestimated, and experience delays or receive fewer referrals for AV replacement (AVR). However, women tend to benefit from transcatheter AVR (TAVR) with a long-term survival advantage over men, although the incidence of vascular complications and bleeding events in 30 days after TAVR is higher in women. Surgical AVR (SAVR) in women has high operative risk, is technically demanding and has poorer outcomes with increased mortality at 30 days compared to men. According to the STS score and EuroSCORE, the female sex itself is considered a risk factor for SAVR. Therefore, addressing sex-related disparities in AS and increasing awareness among physicians promises improved diagnosis and treatment, facilitating equitable care and the development of sex-specific personalized medicine.

Revisiting Peripartum Cardiomyopathy: A Case Report and Review

Peripartum cardiomyopathy (PPCM) is a rare and idiopathic disease characterized by left ventricular dilation and systolic dysfunction, that occurs late in pregnancy or during the postpartum period. Diagnosis is typically achieved through transthoracic echocardiography and cardiac magnetic resonance imaging (MRI). Management includes standard heart failure therapies such as beta-blockers, ACE inhibitors, and diuretics, with the addition of bromocriptine to target the prolactin pathway involved in PPCM pathophysiology. This report presents a case of a 31-year-old female with a history of acute lymphoblastic leukemia who, following an uncomplicated pregnancy, presented with acute heart failure symptoms. Initial evaluations suggested pulmonary embolism, but further diagnostic workup, including echocardiography and cardiac MRI, confirmed PPCM. The patient was treated with diuretics, ACE inhibitors, and beta blockers. Significant improvement was observed, with complete resolution and normal cardiac function at the 6-month follow-up.

Evaluation of electrocardiographic criteria for predicting left ventricular hypertrophy and dilation in presence of left bundle branch block

BackgroundThe utility of standard published electrocardiographic (ECG) criteria for left ventricular hypertrophy (LVH) in patients with left bundle branch block (LBBB) is not established. We have previously shown that in ECGs demonstrating LBBB, QRS duration outperforms vectorcardiographic X, Y, Z lead and root-mean-squared (3D) amplitudes and voltage-time-integrals in diagnosing LVH and dilation. We sought to evaluate diagnostic yields of published LVH criteria versus QRS duration for ECG based diagnosis of LVH and dilation in presence of LBBB. MethodsWe included adult patients with typical LBBB having ECG and transthoracic echocardiogram performed within 3 months of each other in 2010–2020. We obtained area under receiver-operator characteristic curve (AUC) for QRS duration and each of the published ECG LVH criteria to predict increased LV mass indexed (↑LVMi, women >95 g/m2, men >115 g/m2) and LV end diastolic volume indexed (↑LVEDVi, women >61 mL/m2, men >74 mL/m2). ResultsAmong 413 adults (53 % women, age 73 ± 12 yr) with LBBB, the traditional LVH criteria performed poorly to detect ↑LVMi or ↑LVEDVi. Cornell voltage-duration product had the highest AUCs (↑LVMi 0.634, ↑LVEDVi 0.580). QRS duration had a higher AUC for diagnosing ↑LVMi (women 0.657, men 0.703) and ↑LVEDVi (women 0.668, men 0.699) compared to any other criteria. ConclusionsIn patients with LBBB, prolonged QRS duration (women ≥150 ms, men ≥160 ms) is a superior predictor of LVH and dilation than traditional ECG-based LVH criteria.

Ross Confers More Favorable Left Ventricular Remodeling Compared With Mechanical Aortic Valve Replacement.

Background: Aortic valve disease results in left ventricular (LV) dilation and/or hypertrophy. Valve intervention may improve, but not normalize flow dynamics. We hypothesized that LV remodeling would be more favorable following the Ross procedure versus mechanical aortic valve replacement (mAVR). Methods: Patients who were 18 to 50 years of age and underwent Ross or mAVR from 2000 to 2016 at a single institution were retrospectively reviewed. Propensity score matching was performed and yielded 27 well-matched pairs. Demographics and echocardiographic variables of LV morphology and wall thickness were collected. Those with > mild residual valve disease were excluded. Primary endpoints included LV morphology. T test and Fisher exact test analysis were used for statistical comparison. Results: Average age at operation (Ross 35.3 ± 10.2 vs mAVR 37.3 ± 8.9 years) did not differ. Indication for operation was similar between groups. Preoperative echocardiographic variables did not differ. At average follow-up duration (Ross 7.9 ± 2.4 vs mAVR 7.3 ± 2.4 years), wall thickness was significantly smaller for Ross compared with mAVR (P = .00715). Only 4/27 (15%) of mAVR patients had normalized LV parameters compared with 16/27 (59%) of Ross patients (P = .000813). Residual hypertrophy was the most common long-term abnormality for mAVR. Conclusion: Following aortic valve replacement with the Ross procedure or mechanical aortic valve prosthesis, the Ross conferred more favorable LV remodeling compared with mAVR. Future directions include analyzing longer follow-up to determine if patterns persist and the impact on cardiac morbidity and mortality.

Predictors of left ventricular dilation and left ventricular aneurysm development in patients with ST-segment elevation myocardial infarction

Aim. To establish predictors of left ventricular (LV) dilatation and post-infarction left ventricular aneurysm (LVA) development in patients with ST-segment elevation myocardial infarction (STEMI) and/or with Q wave.Material and methods. This registry study included patients admitted with STEMI and/or with Q wave in the first 24 hours from the disease onset in the period from November 1, 2022 to March 31, 2023. The study included 138 patients. The mean age of the patients was 62±11 years. Treatment and examination were carried out in accordance with the current Russian clinical guidelines (2020) on STEMI. The levels of stimulating growth factor expressed by genome 2 (sST2), proprotein convertase subtilisin-kexin type 9, N-terminal pro-brain natriuretic peptide and high-sensitivity C-reactive protein were determined in patients by enzyme immunoassay on the first day of the disease. The patients were divided into two following groups: group 1 — patients with LV dilatation/LVA, n=25 (18,1%), group 2 — patients without LV geometry disorders, n=113 (81,9%). Univariate and multivariate regression analyzes were performed to determine independent predictors of LV dilation/postinfarction LVA.Results. This study showed that with an increase in sST2 levels by 1 ng/L, the probability of LV dilation/LVA formation increase by 1,53 times. Anterior location of myocardial infarction increases the probability of LV dilation/LVA formation by 63,55 times. An increase in eGFR on day 2 of hospitalization by 1 ml/min/1,73 m2 reduces the probability of LV dilatation/LVA formation by 1,07 times.Conclusion. The study showed that anterior location of myocardial infarction and increased sST2 levels increase the probability of LV dilation/LVA formation.

Association Between Serial B-Type Natriuretic Peptide Levels, Vasoactive Drug Weaning, and Adverse Cardiovascular Outcomes in Pediatric Heart Failure.

Children hospitalized with acute decompensated heart failure (ADHF) frequently require intravenous vasoactive (IVV) support drugs and are at risk for adverse cardiovascular (ACV) outcomes. We wished to assess whether serial changes in B-type natriuretic peptide (BNP) levels are associated with successful weaning off IVV support and/or prespecified ACV outcomes in children hospitalized with ADHF. Children hospitalized with ADHF from 2005 to 2021 at our institution were assessed for serial changes in BNP, weaning off of IVV support, and ACV outcomes. Changes in BNP level were evaluated using linear mixed-effects modeling. Bonferroni correction was used to adjust for multiple hypothesis testing. In 131 hospitalizations of children with ADHF, the median age was 4.8 years, with 74% receiving IVV support. ACV outcomes occurred in 62 children. IVV support was associated with lower admission left ventricular ejection fraction (26.7% versus 32%, P=0.002), more severe left ventricular dilation (left ventricular internal diastolic dimension Z score 5.9 versus 3.1, P=0.021) moderate or more mitral regurgitation (41.3% versus 20.6%, P=0.038), and qualitative right ventricular systolic dysfunction (in 45.4% versus 11.8%, P<0.001). Decline in BNP levels was more rapid in patients who were successfully weaned from IVV support (-0.20 versus -0.03 2log pg/mL per day, P<0.001) and in the non-ACV group (-0.17 versus -0.03 2log pg/mL per day, P<0.001). Right ventricular systolic dysfunction was an independent risk factor for ACV (odds ratio, 2.49; P=0.045). The declining rate of serial BNP levels was associated with weaning from IVV support and no ACV outcomes in children hospitalized with ADHF. Right ventricular systolic dysfunction was associated with ACV outcomes.

Blood metal concentrations and cardiac structure and function in total joint arthroplasty patients.

There is concern regarding potential long-term cardiotoxicity with systemic distribution of metals in total joint arthroplasty (TJA) patients. To determine the association of commonly used implant metals with echocardiographic measures in TJA patients. The study comprised 110 TJA patients who had a recent history of high chromium, cobalt or titanium concentrations. Patients underwent two-dimensional, three-dimensional, Doppler and speckle-strain transthoracic echocardiography and a blood draw to measure metal concentrations. Age and sex-adjusted linear and logistic regression models were used to examine the association of metal concentrations (exposure) with echocardiographic measures (outcome). Higher cobalt concentrations were associated with increased left ventricular end-diastolic volume (estimate 5.09; 95%CI: 0.02-10.17) as well as left atrial and right ventricular dilation, particularly in men but no changes in cardiac function. Higher titanium concentrations were associated with a reduction in left ventricle global longitudinal strain (estimate 0.38; 95%CI: 0.70 to 0.06) and cardiac index (estimate 0.08; 95%CI, -0.15 to -0.01). Elevated cobalt and titanium concentrations may be associated with structural and functional cardiac changes in some patients. Longitudinal studies are warranted to better understand the systemic effects of metals in TJA patients.

Luminescence "Turn-On" Sensing of Brain Natriuretic Peptide (BNP) - Dilated Cardiomyopathy Biomarker Based on the MoS2 Nanosheet Quenched Terbium Citrate Complex.

Dilated cardiomyopathy (DCM), known as myocardial metabolic dysfunction, is recognized as a clinical condition characterized by left ventricular dilation or improper contraction of cardiac muscles in the absence of coronary atherosclerosis and hypertension. It is an independent risk factor for cardiac function caused by a hyperglycemic condition in diabetic patients leading to heart failure (HF), which renders the early diagnosis of DCM highly challenging. Hence, detection of early diagnostic biomarkers in blood serum to identify DCM conditions is quite requisite. Brain natriuretic peptide (BNP) is a well-recognized biomarker for heart failure and reported as an early diagnostic biomarker for DCM. In this work, we developed a terbium citrate based MoS2 nanosheet (NS) coupled immunoprobe for the sensitive detection of BNP. The antibody conjugated Tb-citrate complex exhibits green fluorescence, which is quenched by the introduction of MoS2 NS. On subsequent addition of antigen BNP, the fluorescence is enhanced because of specific antigen-antibody interaction. The probe is selective and sensitive toward BNP in a linear range from 30.76 to 849.85 pg/mL with a low LOD of 3.87 pg/mL. The probe is validated in spiked human serum samples with good recovery percentage.

Intramyocardial immunomodulation with human CD16+ monocytes to treat myocardial infarction in pig: a blind randomized preclinical trial.

Human CD16+ monocytes (hCD16+ Ms) have proangiogenic properties. We assessed the feasibility, safety and efficacy of hCD16+ Ms in a porcine model of myocardial infarction (MI). A total of 27 female Large White pigs underwent MI with reperfusion and cardiac magnetic resonance (CMR). Five days later, animals received intramyocardial injections of hCD16+ Ms in saline (n = 13) or saline only (n = 14). hCD16+ Ms were selected from leucocyte cones. Feasibility/safety endpoints included injury at injected sites, malignant arrhythmias, cancer, haematoma, left ventricular (LV) dilatation, troponin release and downstream organ injury. Co-primary efficacy outcome included LV scar and ejection fraction (LVEF) at 30-day post-injections by CMR. Immunohistochemistry included neo-angiogenesis, fibrosis, markers of myofibroblast and inflammation. Four animals were excluded before injections due to untreatable malignant arrhythmias or lung injury. Median cell number and viability were 48.75 million and 87%, respectively. No feasibility/safety concerns were associated with the use of hCD16+ Ms. The LV scar dropped by 14.5gr (from 25.45 ± 8.24 to 10.8 ± 3.4 gr; -55%) and 6.4gr (from 18.83 ± 5.06 to 12.4 ± 3.9gr; -30%) in the hCD16+ Ms and control groups, respectively (p = 0.015). The 30-day LVEF did not differ between groups, but a prespecified sub-analysis within the hCD16+ Ms group showed that LVEF was 2.8% higher and LV scar 1.9gr lower in the subgroup receiving a higher cell dose. Higher tissue levels of neo-angiogenesis, myofibroblast and IL-6 and lower levels of TGF-β were observed in the hCD16+ Ms group. The use of hCD16+ Ms in acute MI is feasible, safe and associated with reduced LV scar size, increased tissue levels of neo-angiogenesis, myofibroblasts and IL-6 and reduced pro-fibrotic TGF-β at 30-day post-injections. A higher cell dose might increase the LVEF effect while reducing scar size, but this warrants validation in future studies.

Abstract Tu085: The β IV -spectrin/STAT3 Complex regulates the orientation of cardiac hypertrophic growth

Background: Cardiac hypertrophy is a major risk factor for adverse cardiovascular events including heart failure and arrhythmia. However, the precise orientation of cell and organ growth varies considerably depending on stress type and duration with important implications for cardiac function. Despite this, little is known regarding the mechanisms that regulate hypertrophic orientation. Here we evaluate the role of the cytoskeletal protein β IV -spectrin and signal transducer and activator of transcription (STAT3) in directing the orientation of pressure overload-induced hypertrophy. Methods: Transgenic mouse models with altered STAT3 signaling through modified interaction with its scaffolding partner β IV -spectrin, or phospho-regulation of STAT3 directly, were evaluated at baseline and transaortic constriction (TAC) for its role in promoting concentric versus eccentric morphologies and resulting impact on systolic function. Unbiased screening of gene expression from these structurally divergent states were evaluated for pathways responsible for directing myocyte length/width. These pathways were tested in vitro using primary mouse myocytes and in vivo to tune growth patterns for therapeutic intervention. Results: Loss of β IV -spectrin or direct STAT3 activation promoted a preferential increase in myocyte length over width, resulting in dilation of the left ventricular (LV) chamber (eccentric hypertrophy) and decreased systolic function. Conversely, preservation of β IV -spectrin favored an increase in myocyte width without LV dilation (concentric hypertrophy) and preserved systolic function in response to TAC. Differential expression of genes associated with microtubule dynamics were identified in concentric vs. eccentric hypertrophic states. In vitro assays revealed a relationship between β IV -spectrin/STAT3 signaling and microtubule stability which impacted spatial distribution of mRNA for the sarcomeric gene actc1 . Finally, intervention with pharmacologic STAT3 inhibition following chronic 6-week TAC successfully recovered concentric growth with improved systolic function. Conclusions: These data identify a novel and pivotal role for β IV -spectrin/STAT3 to modify microtubule dynamics and sarcomeric transcript distribution to direct myocyte geometry and therapeutically serve in the prevention or recovery from HF. These mechanisms further illustrate the unique separation of hypertrophic drivers from growth orientation as distinct pathways in cardiac remodeling.

Abstract Or125: Numb Family Proteins regulate left ventricular compaction by modulating autophagic process

Background: Left ventricular noncompaction (LVNC) is a type of cardiomyopathy, which patients manifest clinical features of heart failure, arrhythmias, thrombotic events, and sudden death. We previously found that the ablation of Numb(Nb) , and its homologue Numbl(Nl) at early stage, causes LVNC defects resulting in embryonic lethality. In this study, we found that mice with Nb and Nl deletion at later stage survive to adulthood and develop toLVNC cardiomyopathy. Method: We applied aMHC-Cre to delete and generate Nb and Nl double knockout (ADKO); examine the structure and functions of the ADKO hearts via echocardiography (ECHO); determine the heart arrhythmia via telemetry; determine the Nb subcellular localization via a Nb overexpression line (R26-Flag:mCherry:Numb); and determine the mechanistic function of NFPs in autophagy via autophagic reporter, electron microscopy, and molecular and biochemical assays. Results: The cTnT-Cre mediated Nb and Nl deletion causes LVNC and embryonic lethality, while the ADKO can survive to adulthood and died between eight- and twelve-month-old. The ADKO hearts display LVNC by two months of age, a reduced systolic function by four months old, and left ventricular remodeling and dilatation starting at six months old. ADKO hearts manifest major clinical features of LVNC, including arrhythmias and thrombosis. ADKO hearts exhibit significant accumulation of damaged mitochondria, autophagosomes and autophagolysosomes compared to controls. Biochemical analyses reveal elevated levels of p62 and a higher ratio of LC3II/LC3I in ADKO hearts. NFP null cells and ADKO hearts exhibit abnormal autophagic flux, characterized by arrested at autophagolysosome, increased expression of Lamp1 and Lamp2, but reduced levels of cathepsin D. Mass spectrometry analyses reveal Numb's interaction with proteins involved in endocytosis and autophagy. Consistently, Numb localizes to autophagosomes and autophagolysosomes. Conclusion: NFPs regulate left ventricular compaction at both embryonic and postnatal stages, suggesting that LVNC can be both congenital and acquired. As LVNC mice progress, they develop dilated cardiomyopathy (DCM) at later stage, suggesting that LVNC can occur independently at early stage, and is associated with DCM at later stage. Deletion of NFPs in cardiomyocytes disrupts endocytosis and autophagic flux. Our studies suggest that NFPs mediated endocytosis and autophagy are essential for left ventricular compaction.

Abstract Tu062: FLNC Deficiency Triggers Unfolded Protein Response and Leads to Dilated Cardiomyopathy

Background: The FLNC gene encodes filamin C, which is highly expressed in cardiomyocytes. Dysfunction of filamin C, due to different types of FLNC mutations, has been reported to be associated with various types of cardiomyopathy. Truncating mutations in FLNC often result in insufficient expression of filamin C, resulting in dilated cardiomyopathy (DCM). However, the specific processes via which the deficiency of filamin C causes DCM remain incompletely comprehended. Aims: To investigate the pathogenic mechanisms of DCM caused by the deficiency of filamin C in cardiomyocytes using a mouse model with cardiac-specific knockout of Flnc and to explore potential therapeutic approaches. Methods and Results: We used tamoxifen to induce cardiac-specific Flnc gene knockout in cardiomyocytes and found that mice with cardiac-specific Flnc knockout exhibited left ventricular dilation, heart failure, increased heart weight, cardiomyocyte enlargement and fibrosis, suggesting that Flnc deficiency in cardiomyocytes causes DCM. Transcriptional profiling of primary cardiomyocytes isolated on the seventh day after tamoxifen injections showed the activation of ER stress and the unfolded protein response (UPR) upon Flnc deletion. Then we measured the expression levels of proteins in UPR pathway in cardiac tissue and found that PDI and pIRE1a proteins were significantly upregulated, while there were no changes in the other two branches of UPR, including the PERK and ATF6 branches. Intraperitoneal injection of a PDI inhibitor E64FC26 significantly improved heart function and reduced fibrosis in cardiac-specific Flnc deletion mice. Conclusion: Cardiac-specific knockout of Flnc leads to DCM in mice, during which the UPR pathway is activated. Treatment with the PDI inhibitor E64FC26 improves the heart function and the fibrosis in Flnc -deficient DCM mice, offering novel perspectives on the pathological mechanisms of DCM and providing new insights into therapeutic strategies in treating DCM caused by FLNC dysfunction.

Abstract We104: A New Small-Molecule ErbB4 Agonist Attenuates Adverse Ventricular Remodeling After Myocardial Infarction In a Sex-Specific Manner

Background: The beneficial effects of the neuregulin/ErbB pathway on the diseased heart have been well-established. The cardioprotective aspects of neuregulin are largely attributable to the activation of the ErbB4 receptor. We recently developed a small-molecule selective ErbB4 agonist, which reduced collagen production in fibroblasts and prevented oxidative-stress induced cardiomyocyte death in vitro . Hypothesis: We hypothesized that the ErbB4 agonist (referred to as compound, Cpd), would attenuate left ventricular remodeling, reduce interstitial cardiac fibrosis and preserve cardiac function in a murine model of myocardial infarction (MI). Since there is a potential interaction between the ErbB4 receptor and the estrogen receptor, we further hypothesized these effects would be sex-dependent. Methods: Mice were divided by sex and then further divided into three experimental groups: a sham group, an MI group receiving Cpd (MI/Cpd), and a control MI group receiving vehicle only (MI/Veh). Mice started treatment with either Cpd (2mg/kg/d) or its vehicle through subcutaneous osmotic minipumps seven days after MI. Cardiac ultrasound was performed weekly until mice were sacrificed after four weeks of treatment. Hearts were excised and stained with Masson’s trichrome to assess interstitial cardiac fibrosis in myocardium remote from the infarction scar. Results: In females (n=25), Cpd significantly decreased left ventricular end-diastolic volume compared to vehicle (Fig.1A, 80±23 µl vs.108±29µl, p=0.045) and induced a slightly increased left ventricular ejection fraction (Fig.2A, 32±12% vs. 22±9%, p=0.086). In addition, Cpd significantly reduced reactive interstitial fibrosis (fibrotic area, Fig.3A, 1.4±1.0% vs. vehicle: 3.8±3.1%, p=0.036) in females. In males (n=30), Cpd had no significant effects on either of the parameters mentioned above (Fig.1B, 2B, 3B). Conclusion: Treatment with the novel small-molecule ErbB4 agonist attenuates left ventricular dilation and reactive interstitial fibrosis after MI in female mice, but not in males. These data support the premise that small molecule-induced ErbB4 activation is a potential new therapy for heart failure, especially in female patients. The mechanisms underlying the sex-dependent effects warrant further exploration.

Abstract Mo106: Inhibition of microRNA-200c promotes regeneration of the ischemic injured myocardium through activation of developmental pathways

Ischemic injury and adverse post-infarction myocardial remodeling are major causes of heart failure worldwide. Strategies designed to offset cell death with cardiomyocyte regeneration have, to date, not translated to routine clinical practice. Mir-200c modulates the transcripts of cardiogenic transcription factors (TFs) Tbx5 , Gata4 , Mef2c to promote myocyte maturation. We hypothesized that inhibition of mir-200c activity would result in postnatal myocyte de-differentiation and replication sufficient to ameliorate post-infarction decompensation after ischemic injury. To test this hypothesis, we preformed left coronary ligation on Wild-Type (WT) and transgenic mice expressing an RNA inhibitor against miR-200c ( PMIS-C ). Echocardiographic left ventricular (LV) ejection fraction (EF) fell from 88.41 ± 1.08% (WT) and 90% ± 1.42% ( PMIS-C ) (p=NS) to 28% ± 11.55% (WT) and 36% ± 9.35% at 1 day post injury (DPI) (p =NS). At 21DPI, LVEF was 27% ± 4.31% (WT) and 64% ± 4.25% ( PMIS-C ) [p ≤ 0.0001]. Post-infarction LV chamber dilation was reversed in PMIS-C mice (1.136 ± 0.19 v 0.67 ± 0.06 p ≤ 0.004 LV Vol/mass). By 9 WPI, PMIS-C heart function within non-significantly levels of sham and function prior to injury. These results indicated that inhibiting miR-200c following ischemic injury can recover cardiac function and prevent LV dilation. Moreover, trichrome stain showed a decrease in fibrosis 3 WPI (WT: 57% ± 17.46 v PMIS-C : 12% ± 3.01 p ≤ 0.001) and 9 WPI. To understand the mechanism causing this phenomenon, we analyzed expression of cardiac progenitor markers. Fold change in expression of TFs Tbx5, Gata4, Mef2c, and Isl1 were increased at 1 and 3 DPI in PMIS-C . At 1 WPI, PMIS-C border zone CMs express markers of a “progenitor-like” cell state seen during cardiogenesis. Conclusions: Inhibiting miR-200c abrogates post-infarction LV remodeling and significantly restores LV systolic function. Ongoing studies are investigating the therapeutic use of PMIS-C through delivery via AAV and nanoparticles.

Abstract Tu075: Cardiac macrophages expressing CD206 and IL-4Ra are required for adverse LV remodeling in HF

Cardiac macrophages significantly expand in chronic heart failure (HF). We tested the hypothesis that CD206 + macrophages expressing interleukin (IL)-4Ra in the failing heart are key drivers of left ventricular (LV) remodeling and ischemic cardiomyopathy. Cardiac macrophages were profiled using flow cytometry in adult male C57BL/6 (WT) mice following non-reperfused myocardial infarction (MI) to induce HF or sham operation. CD206 + macrophages progressively expanded in post-MI hearts during the progression of LV remodeling and comprised ~85% of macrophages at 8 w. These macrophages were exclusively proliferative and predominantly C-C motif chemokine receptor (CCR2) – and major histocompatibility complex (MHC)II hi in failing hearts, with the majority (92%) of CD206 + CCR2 – macrophages expressing LYVE-1, an embryonically-derived resident macrophage marker. Nearly half of cardiac CD206 + macrophages expressed IL-4Ra; the abundance of CD206 + IL-4Ra + directly correlated with LV dysfunction and fibrosis. Intramyocardial adoptive transfer of IL-4-polarized bone marrow derived CD206 + macrophages induced progressive LV dilation, dysfunction and fibrosis over 4 w in naïve recipient mice. To evaluate the role of CD206 + IL-4Ra + macrophages in LV remodeling, we used male and female LysM CreERT2 ;IL-4Ra F/F mice that allow for inducible myeloid-specific IL-4Ra gene deletion. Administration of tamoxifen from at 4 to 10 w post-MI (in established HF), effectively deleted IL-4Ra in cardiac macrophages and significantly reduced CD206 + macrophage abundance and proliferation in the remodeling heart. Myeloid-specific IL-4Ra deletion further prevented LV remodeling progression, improved fibrosis and neovascularization, and alleviated LV systolic dysfunction, while suppressing expansion of cardiac immune cells and blood Ly6C high monocytosis. We conclude that an expanded and proliferative population of CD206 + IL-4Ra + macrophages primarily derived from resident macrophages are key mediators of pathological LV remodeling and fibrosis. Inhibition of CD206 + macrophage IL-4Ra signaling may be a fruitful therapeutic approach to alleviate disease progression in HF.

Abstract Tu129: Collagen Peptide modulates Enzymatic Activity post-Myocardial Infarction

Matrix metalloproteinases (MMPs) play critical roles post-myocardial infarction (MI) and directly correlate with adverse LV remodeling. Of the MMPs, MMP-9 shows the highest correlation with MI patient mortality. Clinical trials trying to inhibit MMP-9 were unsuccessful or detrimental, mostly because MMP-9 has critical roles post-MI and inhibition results in exacerbation of adverse remodeling. Previously, we reported a collagen peptide – p1159 – to reduce LV dilation and adverse LV remodeling post-MI. Recently, we discovered p1159 acts as an MMP-9 competitive substrate and reduces substrate proteolysis in vitro . Herein, we investigated whether p1159 can act as a competitive substrate in vivo to reduce proteolysis of endogenous substrates post-MI without inhibiting MMP-9 activity. Also, we compared p1159 actions to those of a MMP-9 inhibitor (MMP-9i). We hypothesized that animals that receive p1159 would show reduced inflammation and adverse remodeling compared to those that received MMP-9i. Adult male and female C57Bl/6 mice (n = 6-8/group) were grouped as follows: saline (control); p1159; MMP-9i, and p1159 + MMP-9i. We performed baseline echocardiography followed by surgery to induce a permanent occlusion MI model. Three hours later, mice received a randomized osmotic mini-pump to continuously deliver p1159 (14μg/day/kg body weight) or vehicle (saline, 0.9%) and/or MMP-9i (10mg/kg body weight, JNJ 0966 by gavage). The LV and plasma were harvested on day 3 (D3) and D5 for downstream proteomics analysis following a final echocardiographic assessment. Infarct sizes were similar between groups, indicating same level of initial injury. Compared to control, p1159 did not inhibit activity or levels of MMP-9, while animals treated with MMP-9i showed significantly reduced MMP-9 activity. As expected, p1159 reduced (p &lt; 0.05) substrate cleavage, as seen by analysis of the LV peptidome, particularly at D3. Substrates that displayed a reduction in proteolysis included fibrinogen, MIF, myosin, titin, and tubulin. These data support p1159 as a competitive substrate of MMP-9 that can modulate its activity without inhibition. Moreover, these results may explain the previously reported effect of p1159 at reducing LV dilation and improving systolic function.

Deep Learning-Based Electrocardiogram Analysis Predicts Biventricular Dysfunction and Dilation in Congenital Heart Disease

BackgroundArtificial intelligence–enhanced electrocardiogram (AI-ECG) analysis shows promise to detect biventricular pathophysiology. However, AI-ECG analysis remains underexplored in congenital heart disease (CHD). ObjectivesThe purpose of this study was to develop and externally validate an AI-ECG model to predict cardiovascular magnetic resonance (CMR)-defined biventricular dysfunction/dilation in patients with CHD. MethodsWe trained (80%) and tested (20%) a convolutional neural network on paired ECG-CMRs (≤30 days apart) from patients with and without CHD to detect left ventricular (LV) dysfunction (ejection fraction ≤40%), RV dysfunction (ejection fraction ≤35%), and LV and RV dilation (end-diastolic volume z-score ≥4). Performance was assessed during internal testing and external validation on an outside health care system using area under receiver-operating curve (AUROC) and area under precision recall curve. ResultsThe internal and external cohorts comprised 8,584 ECG-CMR pairs (n = 4,941; median CMR age 20.7 years) and 909 ECG-CMR pairs (n = 746; median CMR age 25.4 years), respectively. Model performance was similar for internal testing (AUROC: LV dysfunction 0.87; LV dilation 0.86; RV dysfunction 0.88; RV dilation 0.81) and external validation (AUROC: LV dysfunction 0.89; LV dilation 0.83; RV dysfunction 0.82; RV dilation 0.80). Model performance was lowest in functionally single ventricle patients. Tetralogy of Fallot patients predicted to be at high risk of ventricular dysfunction had lower survival (P < 0.001). Model explainability via saliency mapping revealed that lateral precordial leads influence all outcome predictions, with high-risk features including QRS widening and T-wave inversions for RV dysfunction/dilation. ConclusionsAI-ECG shows promise to predict biventricular dysfunction/dilation, which may help inform CMR timing in CHD.