Left Ventricular Cardiac Function Research Articles

A newly developed small-molecule ErbB4 agonist reduces reactive cardiac fibrosis and adverse ventricular remodelling after myocardial infarction in a sex-specific manner

Abstract Background The beneficial effects of the neuregulin/ErbB pathway on the diseased heart have been well-established. The anti-fibrotic and 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 cultured fibroblasts and prevented oxidative-stress induced cardiomyocyte death in vitro. Purpose In order to evaluate the in vivo effects of this small-molecule ErbB4 agonist (referred to as compound, Cpd), we assessed its effect on left ventricular remodelling, cardiac fibrosis and cardiac function in a murine model of myocardial infarction (MI). Since there is a potential interaction between ErbB4 and the oestrogen receptor, we also aimed to evaluate whether these effects were sex-dependent. We hypothesised that Cpd would attenuate left ventricular remodelling, reduce cardiac fibrosis and help retain cardiac function in a sex-specific manner. 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). MI was induced by ligating the left descending coronary artery. Seven days after MI, mice started treatment with either Cpd (2mg/kg/d) or its vehicle through subcutaneous osmotic minipumps. 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 reactive cardiac fibrosis in the myocardium of the left ventricle, located remote from the infarction scar. A WGA-isolectinB4-DAPI immunofluorescent stain was performed to assess cardiomyocyte cross-sectional area in order to evaluate cardiomyocyte hypertrophy. Results In females (n=25), Cpd significantly decreased left ventricular end-diastolic volume compared to vehicle (LVEDV, Fig.1A, 80±23 µl vs.108±29 µl, p=0.045) and induced a slightly increased left ventricular ejection fraction (LVEF, Fig.1B, 32±12% vs. 22±9%, p=0.086). In addition, Cpd significantly reduced reactive interstitial fibrosis myocardium (Fig.1C, fibrotic area, 1.4±1.0% vs. vehicle: 3.8±3.1%, p=0.0363). In males (n=30), Cpd had no significant effects on either of the parameters mentioned above, (Fig.1E-G). There was no significant treatment effect in either group on cardiomyocyte cross sectional area (Fig.1D, Fig.1H). 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.Figure 1

Left fascicular pacing is not inferior to left bundle branch pacing in preserving ventricular mechanical synchrony and cardiac function

Abstract Background Left bundle branch pacing (LBBP) has emerged as a more physiological alternative to right ventricular pacing.However, capturing the pre-divisional LBB is not easy to accomplish. This study investigates if left fascicular pacing(LFP), defined as the capture of one of the LBB fascicles, could achieve comparable left ventricular (LV) mechanical synchronicity and cardiac function compared to LBBP. Methods Thirty-one patients with pacing indication for bradycardia were retrospectively collected: LBBP was successfully performed in 13 patients and 18 achieved LFP. All patients underwent echocardiography before and after implantation and at one-year follow-up. Left ventricular (LV) volumes, ejection fraction (EF) and global longitudinal strain (GLS) were measured. The lateral-septal (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking and septal strain patterns were also assessed. Results Although LW-SW work difference were significantly higher in the LBBP groups than that in the LFP group at baseline(272±269 mmHg*% vs 25±279mmHg*%,p=0.02), a similar increase in LW-SW work difference was observed during follow-up(199±342 mmHg*% vs 371±384mmHg*%,p=0.21). In addition, both LFP and LBBP induced septal flash or apical rocking in some patients, and resulted in subtle changes in strain patterns, which were not significantly different between groups. At one year follow-up, LV ejection fraction (EF) remained almost unchanged in both LBBP and LFP patients(ΔLVEF: 1.1+3.1% vs -0.3±4.8%,p=0.35) , and global longitudinal strain (GLS) was slightly and equally decreased in LFP compared to LBBP (ΔLVGLS: -1.6±2.3% vs -1.2±2.7%,p=0.69). Conclusion LFP and LBBP did not differ in mechanical dyssynchrony or LV remodelling.

Reduced stroke volume by resting 2-dimensional echocardiography negatively affects survival in patients with abnormal ejection fraction

Abstract Background Abnormal (<50%) ejection fraction (EF) is a cornerstone of risk stratification and therapy, but also an imperfect proxy of left ventricular (LV) cardiac pump function, better assessed with stroke volume (SV). Aim To assess the value of SV in stratifying risk of patients with abnormal EF. Methods In a prospective, observational, multicenter study, we recruited 746 patients (age 66± 11 years, 536 males, 72%, 359 with previous myocardial infarction, 48%) with chronic coronary syndromes (CCS) and EF <50% referred for resting transthoracic echocardiography with technically successful 2-dimensional volumetric echocardiography in 17 accredited laboratories. We quantitatively assessed LV end-diastolic volume (EDV) and end-systolic volume (ESV) by Simpson’s biplane method. EF (EDV-ESV/EDV) and SV (EDV-ESV) were calculated from LV volumes. The outcome end-point was all-cause death. Results EF was 39±9%, SV 48±20 ml. There were 100 all-cause deaths during a median follow-up of 796 days (interquartile range 420-1286 days). Receiver-operating curve analysis identified SV≤31.4 ml/b as the best cut-off for predicting mortality. At multivariable analysis, after adjustment for age and prior myocardial infarction, EF <40% and SV ≤31.4 ml/b were significantly associated with decreased survival (HR 2.09, 95%, confidence intervals 1.09-4.01, p=0.024). The annual mortality was lowest (3.19%) in the group with mildly reduced (40-49%) EF and normal (>31.4 ml) SV, and highest (8.30%) in patients with both reduced EF and abnormal SV: see figure. Conclusion Patients with CCS and abnormal EF are a prognostically heterogeneous group, and the mortality rate is almost 3-times worse in patients with reduced EF and abnormal SV compared to patients with mildly reduced EF and normal SV. A simple resting volumetric two-dimensional echocardiography can offer an efficient risk stratification, beyond EF, with no extra imaging or analysis time.Figure

A comprehensive evaluation of available evidence of mavacamten in obstructive HCM: a meta-analysis of randomised controlled trials

Abstract Introduction Obstructive hypertrophic cardiomyopathy (HCM) poses a significant clinical challenge, characterized by left ventricular hypertrophy and impaired cardiac function. mavacamten, a novel medication targeting the sarcomere protein myosin, has emerged as a promising therapeutic option for patients with symptomatic obstructive HCM. Despite its potential efficacy, the comparative effectiveness and safety of Mavacamten remain uncertain, necessitating a comprehensive evaluation of available evidence. Purpose We aimed to give a comprehensive appraisal on mavacamten as a treatment option for patients with obstructive HCM informing clinical decision-making. Methods We systematically searched PubMed, Web of Science, Scopus, and Cochrane Central, and EMBASE from inception until February 2024. We included randomised controlled trials (RCTs) comparing mavacamten versus placebo in patients with obstructive HCM. The primary outcomes were improvement in NYHA class, Change from baseline in KCCQ-CSS, and the incidence of atrial fibrillation. All data were pooled as either Mean difference in the random effect model with the corresponding SD or pooled as RR and 95% CI for dichotomous data. Results Four randomised controlled trials involving 503 patients were included in the final analysis. the overall odds ratio demonstrated a substantial preference for Mavacamten in achieving more than a one-level improvement in NYHA functional class from baseline (OR: 3.83 (95% CI [2.54 to 5.77], P=0.0001). However, there was no significant difference in terms of KCCQ-CSS (MD= 1.06, 95% CI [ -0.03 to 2.15], P=0.06) or the incidence of atrial fibrillation (OR=1.27, 95% CI [0.51 to 3.14], P=0.60). Conclusion Mavacamten showed a significant improvement on NYHA functional class, with no observed significance in terms of reducing the incidence of AF, or improving the KCCQ-CSS score.KCCQ-CSSNYHA

Effect of radiofrequency ablation on improving cardiac structure and function in patients with atrial fibrillation and functional mitral regurgitation

Objective: Exploring the effect of radiofrequency ablation treatment to restore sinus rhythm on the improvement of functional mitral regurgitation (FMR) and cardiac structure in patients with atrial fibrillation combined with moderate or severe FMR, compared with drug therapy alone. Methods: This retrospective cohort study consecutively enrolled patients diagnosed with persistent atrial fibrillation and moderate or severe FMR who were admitted to the Third Affiliated Hospital of Sun Yat-sen University from January 2019 to December 2021. Forty-eight patients who were treated with radiofrequency ablation and maintained sinus rhythm were enrolled in the ablation group, and 63 patients who were treated with medication alone during the same period were in the medicine group. Patients in the ablation group and medicine group were matched in a 1∶1 ratio using a propensity score, and 41 patients were finally included in each of the 2 groups. All patients reexamined echocardiography after 3-month of treatment. The proportion of patients with FMR improvement and the differences in changes of cardiac structural and functional parameters were compared between groups. Results: After propensity score matching, the ablation group was aged (69.3±7.1) years with 21 males (51.2%) and the medicine group was aged (71.3±9.4) years with 21 males (51.2%). The echocardiography after 3-month of treatment showed the rate of FMR improvement was significantly higher in the ablation group than in the medicine group (19 (46.3%) vs. 33 (80.5%), P<0.001), and patients in the ablation group showed a significant decrease in FMR extent (Δmitral regurgitation area: (-1.30±2.64) cm2 vs. (-3.55±2.50) cm2, P<0.001), left atrial size (Δleft atrial diameter: (-0.17±3.78) mm vs. (-2.46±4.01) mm, P=0.009) and E/e' (ΔE/e':-2.54±7.34 vs.-6.34±7.08, P=0.021) compared with the medicine group. There was also a significant decrease in left ventricular size (Δleft ventricular end diastolic diameter: (-3.12±6.62) mm vs. (-0.73±3.62) mm, P=0.046) and significant increase in left ventricular ejection fraction (Δleft ventricular ejection fraction: (2.73±9.69) % vs. (-0.93±5.41) %, P=0.038) in ablation group. Conclusion: Performing radiofrequency ablation to restore sinus rhythm can effectively reduce the severity of mitral regurgitation and improve left atrial and left ventricular remodeling and cardiac function in patients with atrial fibrillation and FMR.

Comparative Study Between the Effects of High Doses of Rosuvastatin and Atorvastatin on Ventricular Remodeling in Patients with ST-Segment Elevation Myocardial Infarction.

Most studies reported that treating ST-Elevation Myocardial Infarction (STEMI) patients with high doses of rosuvastatin or atorvastatin could improve left ventricular remodeling and cardiac function. The current study compared the impact of high doses of rosuvastatin and atorvastatin on hypertrophy, fibrosis markers, serum inflammatory markers, and left ventricular function in STEMI patients after primary percutaneous coronary intervention (PCI). After primary PCI, eighty STEMI patients were randomized to receive either 20 mg of rosuvastatin (n = 40) or 40 mg of atorvastatin (n = 40) once daily for 3 months. Soluble Suppression of Tumorigenicity-2 (sST2), Matrix Metalloproteinase-9 (MMP9), C-Reactive Protein (CRP), lipid parameters, liver enzymes, and echocardiographic parameters were assessed for the two groups at baseline and after 3 months. After 3 months of treatment, a statistically significant reduction was observed in the rosuvastatin group regarding the levels of CRP (16 ± 6 vs. 20 ± 10 mg/L, P = 0.024) and MMP9 (104 ± 33 vs. 130 ± 42 ng/L, P = 0.003) compared with the atorvastatin group. The median percentage decrease in sST2 level in the rosuvastatin group was higher (6.1%) than in the atorvastatin group (2.3%) after 3 months of treatment. Also, in the rosuvastatin group, LVEF was significantly increased (48.5 ± 9 vs. 43.5 ± 11%, P = 0.029), while LVEDV and LVESV were significantly decreased compared to those of the atorvastatin group (101 [81/135] vs. 134 [100/150] ml, P = 0.041) (53 [37/75] vs. 73 [52/92] ml, P = 0.033), respectively. High-intensity rosuvastatin was superior to high-intensity atorvastatin in reducing the inflammatory response and myocardial fibrosis, thus improving ventricular remodeling and cardiac function better in STEMI patients. This randomized controlled trial was registered on October 11, 2022, on ClinicalTrials.gov under registration number: NCT05895123 "retrospectively registered".

Abstract Tu145: Exploring Naltrindole’s hypercontracture attenuating effects during myocardial ischemia via a novel mechanism that produces cardioprotective effects in myocardial ischemia/reperfusion injury

Introduction: Previously, naltrindole (NTI) produced robust cardioprotective effects (e.g.~80% reduction of infarct size) in both ex-vivo (2.5-5µM) and in-vivo (3.75-7.5 mg/kg) rat myocardial ischemia-reperfusion (MIR) injury models. Additionally, we recently showed that NTI 100-200µM attenuated phorbol 12-myristate 13-acetate (PMA) induced polymorphonuclear leukocytes (PMNs) superoxide (SO) release by a novel mechanism of action (MOA) devoid of opioid receptors. Hypothesis: We hypothesize NTI’s novel MOA is a reduction of intracellular calcium (Ca 2+ ). Testing this hypothesis, we conducted isolated perfused MIR assays using KB-R7943(KB). KB is known to reduce intracellular Ca 2+ via inhibition of reverse mode Na + /Ca 2+ exchanger and, therefore, should attenuate myocardial ischemic hypercontracture, infarct size, and left ventricular end diastolic pressure (LVEDP). We predict that both NTI and KB will improve LVEDP and decrease infarct size compared to vehicle (dH 2 O) control and naloxone (NX) used as a negative control. Methods: Hearts were isolated from anesthetized male Sprague Dawley (SD) rats (~300g). We then infused NTI 1.25-5µM, KB 10-20µM, or NX 10µM for 5 min into perfused hearts, just prior to global I(30min)/R(45min). Cardiac left ventricular function was measured via a pressure transducer and infarct size using 1% triphenyltetrazolium chloride staining in the MIR assay. Data were analyzed using ANOVA and Fishers post-hoc analysis, with p&lt;0.05 considered statistically significant. Results: MIR assay: NTI 5µM, 2.5µM, 1.25µM and KB 20 µM reduced infarct size (4.8±3%, n=5, p&lt;0.05), (6.8±0.8%, n=6, p&lt;0.05), (12.2±3%, n=5), and (2.9±2%, n=5, p&lt;0.05) respectively compared to vehicle (14.1±2%, n=9) and NX 10µM controls (18±3%, n=3). NTI 5 µM and KB 20 µM had significantly improved LVEDP to (32.4±11%, n=5, p&lt;0.05) and (22.8±4%, n=5, p&lt;0.05) respectively compared to vehicle control (72.4±6%, n=9) and NX 10µM controls (54.2±8%, n=3) Conclusion: Both NTI (2.5µM, 5µM) and KB (20µM) reduced infarct size and improved LVEDP. The novel MOA of NTI may be mediated via a reduction in intracellular Ca 2+ during myocardial ischemia. The infarct reducing effect of NTI can benefit patients undergoing elective PCI, CABG, and transplant procedures.

HAEMODYNAMIC FORCES ANALYSIS IN PATIENTS WITH PARAVALVULAR REGURGITATION AFTER TAVR: A PROPENSITY–SCORE MATCHED RETROSPECTIVE STUDY

Abstract Background Paravalvular regurgitation (PVR) after TAVR is a frequent complication, but its direct quantification and grading with conventional echocardiography is still limited by several factors. LV remodeling has still a role in the evaluation of PVR and its pathophysiology. Hemodynamic forces (HDF) analysis has emerged as a new tool to evaluate LV cardiac function in addiction to ejection fraction (EF) and global longitudinal strain (GLS). Aim of the study: To evaluate the difference in pre– and post–TAVR HDF in patients with preserved EF, using a propensity–matched analysis comparing patients with more than mild PVR to patients with mild or no PVR. Medis Ultrasound Suite software has been used for the estimation of HDF in order to differentiate earlier LV function modification between the two groups and its relationship with clinical outcomes. Material and Methods 25 patients from two European high–volume centers with more than mild PVR and coupled pre– and post–TAVR echocardiographic evaluation available for HDF analysis were retrospectively included, paired 1:2 with 50 patients, matched for characteristics that may influence HDF analysis and with mild or none PVR. Clinical outcome was a composite of heart failure (HF) valve–related hospitalization and worsening HF at 1 year. Results No significative differences were found at baseline clinical and echocardiography evaluation between the two groups: median age was 83 years, mean LVEF was 61%. Post–procedural echocardiographic evaluation was performed at 34 days after TAVR (IQR 5 – 50). Patients with significant PVR had higher LV end–diastolic volume (p = 0.044), lower endocardial GLS (p = 0.07) and lower LV diastolic apex–base longitudinal forces (LVD Apex–Base) (p = 0.045). The difference between LVD Apex–base pre– and post–TAVR was significantly lower in the significant PVR group (–0.8 vs 0.3%, p = 0.021). At Cox regression analysis, LV longitudinal force (LVLF) Ratio turned out to be predictive of clinical outcome (HR 1.11, 95CI 1.02 – 1.20, p = 0.017) in the overall population. Conclusion HDF analysis seems to be superior to conventional echocardiographic values of left ventricular cardiac function to detect the early effects of LV volume overload in patients with significant PVR after TAVR. Furthermore, in the overall population, LVLF Ratio predicts clinical outcomes and could be a promising new index to better evaluate the development of heart failure in patients with AS undergoing TAVR.

Exogenous Thyroxine Normalizes Decreased Heart Rate in Insulin Resistant OLETF Rats

Diabetic cardiomyopathy (DCM) is defined as heart failure in the absence of overt clinical coronary artery disease, valvular disease, hypertension, and dyslipidemia in diabetic patients. Patients with T2DM display left ventricular dysfunction, fibrosis, and abnormal cell signaling leading to diastolic and systolic dysfunction. Increased left ventricular mass and fibrosis potentially leads to abnormal diastolic function. Substantial data exists demonstrating both insulin-dependent and non-insulin dependent diabetes impairs left ventricular function. During insulin resistance, a metabolic shift occurs favoring fatty acid metabolism at the expense of impaired glucose metabolism, leading to lipotoxicity, increased oxidative stress, and inflammation. Thyroid hormones have shown to be cardioprotective. We have previously shown exogenous thyroxine treatment increased GLUT4 translocation and nuclear factor erythroid 2-related factor 2 (Nrf2) in cardiac tissue, demonstrating the potential to improve glucose metabolism and increase antioxidant defense mechanisms. Insulin resistant, Otsuka Long Evans Tokushima Fatty (OLETF) rats were used to assess the effects of exogenous thyroxine (T4) on left ventricular cardiac function and hemodynamics to assess if the previously observed improvements in cellular metabolism translated to functional improvements. Rats were assigned to three groups: (1) lean, Long Evans Tokushima Otsuka (LETO; n=7), (2) untreated OLETF (n=6), and (3) OLETF + T4 (8 μg/100g BM/d × 6 wks, n=7). Left ventricular function was measured by the pressure-volume system. Heart mass increased in untreated OLETF (1.46 ± 0.08) and treated OLETF (1.61 ± 0.16) compared to LETO (1.19 ± 0.08). Cardiac output (CO) and stroke volume were 26% and 56% greater in untreated OLETF compared to LETO. Heart rate (HR) was 27% lesser in untreated OLETF compared to LETO. While exogenous T4 did not alter CO and SV compared to untreated OLETF, it did normalize HR to LETO levels. The differences in CO between LETO and OLETF suggest that elevated T4 alters the mechanisms (SV vs HR) by which CO is elevated during MetS. The changes may be compensatory to accommodate the cardiac hypertrophy observed in the strain. American Heart Association Award # 946746 APS Porter Physiology Development Fellow (2nd year). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

L-carnitine decreases myocardial injury in children undergoing open-heart surgery: A randomized controlled trial

Myocardial injury in open-heart surgery is related to several factors including ischemia–reperfusion injury, generation of reactive oxygen species, increased production of inflammatory mediators, and enhancement of apoptosis of cardiomyocytes. The aim of this study was to study the effect of L-carnitine on myocardial injury in children undergoing open-heart surgery. This clinical trial was performed on 60 children with congenital heart disease (CHD) who underwent open-heart surgery. They were randomized into two groups: L-carnitine group who received L-carnitine 50 mg\\kg\\day once daily for 1 month before cardiac surgery and control group who received placebo for 1 month before cardiac surgery. Left ventricular cardiac function was assessed by conventional echocardiography to measure left ventricular ejection fraction (LVEF) and two-dimensional speckle tracking echocardiography (2D-STE) to determine left ventricular global longitudinal strain (2D-LV GLS). Blood samples were obtained pre-operatively at baseline before the administration of L-carnitine or placebo and 12 h post-operatively to measure the level of malondialdehyde (MDA), superoxide dismutase (SOD), fas, caspase-3, creatinine kinase-MB (CK-MB), and troponin I. L-carnitine group had significantly lower post-operative level of oxidative stress marker (MDA), apoptosis markers (fas and caspase-3), and myocardial injury markers (CK-MB and troponin I), but they had significantly higher SOD post-operative level compared to the control group. In addition, post-operative LVEF and 2D-LVGLS were significantly lower in the control group compared to L-carnitine group. Conclusion: L-carnitine can reduce myocardial injury, improve post-operative left ventricular cardiac function, and may provide myocardium protection in children with CHD who underwent open-heart surgery. Trial registration: The clinical trial was registered at www.pactr.org with registration number PACTR202010570607420 at 29/10/2020 before recruiting the patients.What is Known:• Myocardial injury in open-heart surgery is related to several factors including ischemia–reperfusion injury, generation of reactive oxygen species, increased production of inflammatory mediators, and enhancement of apoptosis of cardiomyocytes.• L-carnitine was reported to have myocardial protective effects in rheumatic valvular surgery and coronary artery bypass graft (CABG) in adults; however, there is no evidence on its effectiveness in children undergoing open-heart surgery.What is New:• L-carnitine significantly lowered the post-operative level of oxidative stress marker (MDA), apoptosis markers (fas and caspase-3), and myocardial injury markers (CK-MB and troponin I) in the treatment group.• L-carnitine can reduce myocardial injury, improve post-operative left ventricular cardiac function, and may provide myocardium protection in children with CHD who underwent open-heart surgery.

Association between left ventricular remodeling and lipid profiles in obese children: an observational study.

Childhood obesity has become a prominent issue in the society, which can lead to left ventricular remodeling and severe cardiovascular complications in adulthood. It is beneficial to identify the causes of left ventricular remodeling so that targeted measures can be taken to prevent the cardiovascular disease. Therefore, this study aimed to explore the relationship between left ventricular remodeling and changes in blood lipid indexes in obese children. This study was conducted on 40 healthy non-obese children and 140 obese children diagnosed in the pediatric health department of our hospital. Clinical data collected from the two groups were compared. Echocardiography was performed to examine left ventricular configuration and cardiac function. Multiple linear regression analysis was conducted to assess the independent effects of blood lipid levels on echocardiographic parameters. Blood lipid indicators among different left ventricular structural patterns which were classified according to left ventricular mass indexes and relative wall thickness were compared. Obese children exhibited significantly increased height, weight, body mass index (BMI), body fat percentage (BFP), blood pressure, triglycerides, total cholesterol, left ventricular internal diameter (LVIDd), interventricular septum (IVSd), left ventricular posterior wall diastolic thickness (LVPWd), myocardial mass (LVM) and relative wall thickness (RWT), as well as lower high-density lipoprotein cholesterol (HDL-C) and left ventricular ejection fraction (LVEF) compared to the non-obese children (P < 0.05). Multiple linear correlation analysis showed LVM had a significantly positive correlation with BMI (r = 3.21, P = 0.002) and SBP (r = 2.61, P = 0.01); LVMI had a significantly negative correlation with HDL-C (r = -2.45, P = 0.015); RWT had a significantly positive correlation with SBP (r = 2.50, P = 0.013) but a significantly negative correlation with HDL-C (r = -2.35, P = 0.02). Furthermore, there were significant differences in HDL-C values among children with different ventricular configurations (P < 0.05), with the lowest HDL-C value recorded in the concentric hypertrophy group. Obese children will develop left ventricular remodeling. The left ventricular configuration indexes are most significantly associated with serum HDL-C. Lower HDL-C level contributes to severer left ventricular hypertrophy, indicating a concentric hypertrophy pattern.

Gene therapy encoding cell cycle factors to treat chronic ischemic heart failure in rats.

Gene therapies to induce cardiomyocyte (CM) cell cycle re-entry have shown a potential to treat subacute ischaemic heart failure (IHF) but have not been tested in the more relevant setting of chronic IHF. Our group recently showed that polycistronic non-integrating lentivirus encoding Cdk1/CyclinB1 and Cdk4/CyclinD1 (TNNT2-4Fpolycistronic-NIL) is effective in inducing CM cell cycle re-entry and ameliorating subacute IHF models and preventing the subsequent IHF-induced congestions in the liver, kidneys, and lungs in rats and pigs. Here, we aim to test the long-term efficacy of TNNT2-4Fpolycistronic-NIL in a rat model of chronic IHF, a setting that differs pathophysiologically from subacute IHF and has greater clinical relevance. Rats were subjected to a 2-h coronary occlusion followed by reperfusion; 4 weeks later, rats were injected intramyocardially with either TNNT2-4Fpolycistronic-NIL or LacZ-NIL. Four months post-viral injection, TNNT2-4Fpolycistronic-NIL-treated rats showed a significant reduction in scar size and a significant improvement in left ventricular (LV) systolic cardiac function but not in the LV dilatation associated with chronic IHF. A mitosis reporter system developed in our lab showed significant induction of CM mitotic activity in TNNT2-4Fpolycistronic-NIL-treated rats. This study demonstrates, for the first time, that TNNT2-4Fpolycistronic-NIL gene therapy induces CM cell cycle re-entry in chronic IHF and improves LV function, and that this salubrious effect is sustained for at least 4 months. Given the high prevalence of chronic IHF, these results have significant clinical implications for developing a novel treatment for this deadly disease.

FRI607 SGLT2 Inhibition Improves Muscle Oxidative Capacity And Its Relationship With Cardiac Performance In Patients With T2D And Heart Failure

Abstract Disclosure: Y. Qin: None. N.D. Sanchez: None. A.J. Moody: None. F.M. Acosta: None. S. Neppala: None. M. Brown: None. H. Honka: None. B. Todd: None. L.A. Cruz Moreno: None. A.R. Stepanenko: None. S.E. Espinoza: None. N. Musi: None. C. Triplitt: None. G. Clarke: None. E. Cersosimo: None. R.A. DeFronzo: None. C. Solis-Herrera: None. Cardioprotective benefits of SGLT2 inhibitors (SGLT2i) have been largely thought to be coupled to a physiologic increase in plasma ketones, with much interest in the role of adaptive changes in cardiac fuel source in subjects with T2D and HF. Given the changes in the global dynamics of bioenergetics with SGLT2i, and the proven pleiotropic effects of ketone bodies, suggest that, in addition to their cardioprotective function, SGLT2i may influence other organ systems. In particular, how skeletal muscle (SkM), or cardiopulmonary function, respond to these global bioenergetics changes remains largely unknown. A pilot randomized-controlled clinical study was designed to examine the effects of SGLT2i on SkM bioenergetics (31P MRS), &amp; cardiopulmonary function (CPET), and its association with left ventricular cardiac function (MRI). Six subjects (Age=59±2.6, BMI=33.3±1.1, A1c=7.1±0.3) with T2D and HF (&amp;lt;50%) were randomized empagliflozin 25mg/day (SGLT2i) vs. placebo (control) in a 2:1 fashion for 12 weeks. Imaging and clinical evaluations were performed pre- and post-intervention. The SGLT2i group improved EF (28.7 vs. 38.8, p=0.1). SkM 31P MRS at rest, measuring the relative intracellular concentrations of high-energy metabolites of phospholipid breakdown, reduced with SGLT2i, suggesting better energy utilization by the SkM. 31P MRS-after exercise, showed significant improvements in SkM oxidative capacity (KPCR*[PCr], 0.6 to 0.8, p=0.03), with SGLT2i.During CPET testing, the ventilatory anaerobic threshold (VT), with SGLT2i, showed a significant (p=0.05) increase in VT time, suggesting an increase in the time in aerobiosis in these subjects. The minute ventilation-to-carbon dioxide output slope (a strong predictor of cardiopulmonary complications/death) was improved in the SGLT2i group vs. placebo, which could be associated with the CV benefit observed with these agents. Additionally, patient self-reported outcomes (Promis) showed a trend of improvement in the SGLT2i group. In summary, we demonstrate novel and exciting preliminary findings that in patients with T2D &amp; HF, SGLT2i-associated benefits are not isolated to the heart and may also expand to the SkM, including improved oxidative capacity, energy utilization, and SkM recovery post-exercise. With improvements in HF prognostic markers and patient self-reported outcomes. These original findings may represent novel mechanisms contributing to the cardiac benefits of SGLT2i. Presentation: Friday, June 16, 2023

Rivaroxaban, a direct inhibitor of coagulation factor Xa, attenuates adverse cardiac remodeling in rats by regulating the PAR-2 and TGF-β1 signaling pathways.

Factor Xa (FXa) not only plays an active role in the coagulation cascade but also exerts non-hemostatic signaling through the protease-activated receptors (PARs). This study aimed to investigate whether the FXa inhibitor, Rivaroxaban (RIV), attenuates adverse cardiac remodeling in rats with myocardial infarction (MI) and to identify the underlying molecular mechanisms it uses. An MI model was induced in eight-week-old, male Wistar rats, by permanent ligation of the left anterior descending coronary artery. MI rats were randomly assigned to receive RIV or protease-activated receptors 2-antagonist (PAR-2 antagonist, FSLLRY) treatment for four weeks. Histological staining, echocardiography and hemodynamics were used to assess the cardioprotective effects of RIV. Meanwhile, pharmacological approaches of agonist and inhibitor were used to observe the potential pathways in which RIV exerts antifibrotic effects in neonatal rat cardiac fibroblasts (CFs). In addition, real-time PCR and western blot analysis were performed to examine the associated signaling pathways. RIV presented favorable protection of left ventricular (LV) cardiac function in MI rats by significantly reducing myocardial infarct size, ameliorating myocardial pathological damage and improving left ventricular (LV) remodeling. Similar improvements in the PAR-2 antagonist FSLLRY and RIV groups suggested that RIV protects against cardiac dysfunction in MI rats by ameliorating PAR-2 activation. Furthermore, an in vitro model of fibrosis was then generated by applying angiotensin II (Ang II) to neonatal rat cardiac fibroblasts (CFs). Consistent with the findings of the animal experiments, RIV and FSLLRY inhibited the expression of fibrosis markers and suppressed the intracellular upregulation of transforming growth factor β1 (TGFβ1), as well as its downstream Smad2/3 phosphorylation effectors in Ang II-induced fibrosis, and PAR-2 agonist peptide (PAR-2 AP) reversed the inhibition effect of RIV. Our findings demonstrate that RIV attenuates MI-induced cardiac remodeling and improves heart function, partly by inhibiting the activation of the PAR-2 and TGF-β1 signaling pathways.

Inflammation associated with left ventricular hypertrophy in bipolar disorder: A cross-sectional study

ObjectiveInflammation has received increasing attention as a contributor to the pathophysiology of bipolar disorder (BD) and cardiac hypertrophy into heart failure (HF). Accordingly, we chose BD-related inflammatory markers to investigate their relationships with cardiac left ventricular function and structure in BD. MethodsSixty physically healthy and euthymic patients with bipolar I disorder were recruited to compare with 50 healthy normal controls. The echocardiography was performed to estimate left ventricular mass index (LVMI) as a parameter of LV hypertrophy (LVH) and left ventricle ejection fraction (LVEF) as a parameter of systolic function. An LVEF above the normal range (>70%) was defined as a hyperdynamic heart. Participants' levels of inflammatory and atherosclerosis-related parameters were measured. ResultsCompared with normal controls, BD group had significantly higher rates of LVH (63% vs. 42%) and hyperdynamic heart (32% vs. 2%) and higher mean values of LVMI and LVEF. After adjustment for the effects of BMI and age, multiple regression analyses of BD group showed that the peripheral level of interleukin-8 was positively associated with LVMI and the level of soluble tumor necrosis factor receptor 1 (sTNF-R1) was positively associated with LVEF. ConclusionsPatients with BD from young adulthood are likely to have LVH with normal LV function and hyperdynamic heart associated with diastolic dysfunction. Low-grade inflammation may underlie the mechanisms of LV hypertrophy and cardiac dysfunction in BD patients.

The assessment of left ventricular volume and function in gated small animal 18F-FDG PET/CT imaging: a comparative study of three commercially available software tools

BackgroundSeveral software tools have been developed for gated PET imaging that use distinct algorithms to analyze tracer uptake, myocardial perfusion, and left ventricle volumes and function. Studies suggest that different software tools cannot be used interchangeably in humans. In this study, we sought to compare the left ventricular parameters in gated 18F-FDG PET/CT imaging in mice by three commercially available software tools: PMOD, MIM, and QGS.Methods and resultsHealthy mice underwent ECG-gated 18F-FDG imaging using a small-animal nanoPET/CT (Mediso) under isoflurane narcosis. Reconstructed gates PET images were subsequently analyzed in three different software tools, and cardiac volume and function (end-diastolic (EDV), end-systolic volumes (ESV), stroke volume (SV), and ejection fraction (EF)) were evaluated. While cardiac volumes correlated well between PMOD, MIM, and QGS, the left ventricular parameters and cardiac function differed in agreement using Bland–Altman analysis. EDV in PMOD vs. QGS: r = 0.85; p < 0.001, MIM vs. QGS: r = 0.92; p < 0.001, and MIM vs. PMOD: r = 0.88; p < 0.001, showed good correlations. Correlation was also found in ESV: PMOD vs. QGS: r = 0.48; p = 0.07, MIM vs QGS: r = 0.79; p < 0.001, and MIM vs. PMOD: r = 0.69; p < 0.01. SV showed good correlations in: PMOD vs. QGS: r = 0.73; p < 0.01, MIM vs. QGS: r = 0.86; p < 0.001, and MIM vs. PMOD: r = 0.92; p < 0.001. However, EF among correlated poorly: PMOD vs. QGS: r = −0.31; p = 0.26, MIM vs. QGS: r = 0.48; p = 0.07, and MIM vs. PMOD: r = 0.23; p = 0.41. Inter-class and intra-class correlation coefficient were > 0.9 underlining repeatability in using PMOD, MIM, and QGS for cardiac volume and function assessment.ConclusionsAll three commercially available software tools are feasible in small animal cardiac volume assessment in gated 18F-FDG PET/CT imaging. However, due to software-related differences in agreement analysis for cardiac volumes and function, PMOD, MIM, and QGS cannot be used interchangeably in murine research.

Cardiac MRI: An Alternative Method to Determine the Left Ventricular Function.

(1) Background: With the conventional contour surface method (KfM) for the evaluation of cardiac function parameters, the papillary muscle is considered to be part of the left ventricular volume. This systematic error can be avoided with a relatively easy-to-implement pixel-based evaluation method (PbM). The objective of this thesis is to compare the KfM and the PbM with regard to their difference due to papillary muscle volume exclusion. (2) Material and Methods: In the retrospective study, 191 cardiac-MR image data sets (126 male, 65 female; median age 51 years; age distribution 20-75 years) were analysed. The left ventricular function parameters: end-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF) and stroke volume (SV) were determined using classical KfW (syngo.via and cvi42 = gold standard) and PbM. Papillary muscle volume was calculated and segmented automatically via cvi42. The time required for evaluation with the PbM was collected. (3) Results: The size of EDV was 177 mL (69-444.5 mL) [average, [minimum-maximum]], ESV was 87 mL (20-361.4 mL), SV was 88 mL and EF was 50% (13-80%) in the pixel-based evaluation. The corresponding values with cvi42 were EDV 193 mL (89-476 mL), ESV 101 mL (34-411 mL), SV 90 mL and EF 45% (12-73%) and syngo.via: EDV 188 mL (74-447 mL), ESV 99 mL (29-358 mL), SV 89 mL (27-176 mL) and EF 47% (13-84%). The comparison between the PbM and KfM showed a negative difference for end-diastolic volume, a negative difference for end-systolic volume and a positive difference for ejection fraction. No difference was seen in stroke volume. The mean papillary muscle volume was calculated to be 14.2 mL. The evaluation with PbM took an average of 2:02 min. (4) Conclusion: PbM is easy and fast to perform for the determination of left ventricular cardiac function. It provides comparable results to the established disc/contour area method in terms of stroke volume and measures "true" left ventricular cardiac function while omitting the papillary muscles. This results in an average 6% higher ejection fraction, which can have a significant influence on therapy decisions.

Magnesium Improves Cardiac Function in Experimental Uremia by Altering Cardiac Elastin Protein Content.

Cardiovascular complications are accompanied by life-threatening complications and represent the major cause of death in patients with chronic kidney disease (CKD). Magnesium is important for the physiology of cardiac function, and its deficiency is common in CKD. In the present study, we investigated the impact of oral magnesium carbonate supplementation on cardiac function in an experimental model of CKD induced in Wistar rats by an adenine diet. Echocardiographic analyses revealed restoration of impaired left ventricular cardiac function in animals with CKD. Cardiac histology and real-time PCR confirmed a high amount of elastin protein and increased collagen III expression in CKD rats supplemented with dietary magnesium as compared with CKD controls. Both structural proteins are crucial in maintaining cardiac health and physiology. Aortic calcium content increased in CKD as compared with tissue from control animals. Magnesium supplementation numerically lowered the increases in aortic calcium content as it remained statistically unchanged, compared with controls. In summary, the present study provides evidence for an improvement in cardiovascular function and aortic wall integrity in a rat model of CKD by magnesium, as evidenced by echocardiography and histology.

Minocycline pre-treatment up-regulates antioxidant enzymes and enhances the regenerative potential of MSCs in rat myocardial infarction model.

To determine the effect of the pre-treatment of mesenchymal stem cells (MSCs) with minocycline on the expression of antioxidant genes and cardiac repair post myocardial infarction (MI) in rats. Rat bone marrow derived MSCs were used in the study. Cytotoxicity of minocycline in MSCs was determined using JC1 assay to identify a safe drug dose for further experiments. The MSCs were pre-treated with 1.0 µM minocycline for 24 hours and then treated with hydrogen peroxide (H2O2), after that mRNA was isolated and the expression levels of antioxidant genes including peroxiredoxin, glutathione peroxidase, and superoxide dismutase were determined. Finally, minocycline pre-treated MSCs were used to treat rats induced with MI by the ligation of left anterior descending coronary artery. The cardiac function was evaluated at two and four weeks post MI using echocardiography. At 1.0 µM concentration, minocycline was found to be safe for MSCs and used for subsequent experiments. Minocycline pre-treatment was found to up regulate several antioxidant genes in oxidatively stressed MSCs. Furthermore, minocycline pre-treated MSCs displayed greater improvement in cardiac left ventricular function at two and four-weeks post MI as compared to untreated rats. Pre-treatment of MSCs with minocycline enhances the expression of antioxidant genes and promotes their capability to repair cardiac function after MI.

PS-BPB02-4: LEFT VENTRICLE HYPERTROPHY AND DYSFUNCTION WERE EXAGGERATED BY P2RX7 KNOCKOUT BUT UNAFFECTED BY P2RX7 PHARMACOLOGIC BLOCKADE IN ANGIOTENSIN II-INFUSED MICE

Objective: Extracellular adenosine triphosphate released from damaged cells binds to the P2X7 receptor (P2RX7) to activate of immune cells. Our preliminary data demonstrated that P2RX7 plays a role in vascular injury of hypertensive mice. Angiotensin (Ang) II-induced hypertension, vascular injury and aortic perivascular infiltration of activated T cell were attenuated by P2rx7 knockout or P2RX7 pharmacologic blockade. However, whether P2RX7 is involved in Ang II-induced cardiac dysfunction and hypertrophy is unknown. We hypothesized that Ang II-induced left ventricular (LV) dysfunction and hypertrophy would be blunted by P2rx7 knockout or P2RX7 antagonism. Design and method: Ten-to-12-week-old male C57BL/6J wild-type (WT) and P2rx7-/- mice were infused or not with Ang II (1000 ng/kg/min) for 14 days. A second set of Ang II-infused WT mice was infused with the P2RX7 antagonist AZ10606120 (694 ng/kg/min) or vehicle for 14 days. Cardiac LV function and remodeling were determined by ultrasound. Total RNA was isolated from the heart using the mirVana miRNA isolation kit. Relative expression was calculated using the Pfaffl method with 40S ribosomal protein S16 (Rps16) as a reference gene. Hypertrophic and fibrotic markers were studied by reverse transcription-quantitative PCR (RT-qPCR) in cardiac ventricles. Results: Ang II-induced 1.5-fold increase in LV mass/body weight (P &lt; 0.001) and ∽25% decrease in fractional shortening in WT mice and mice receiving AZ10606120 (P &lt; 0.05). These changes were exaggerated in P2rx7-/- mice (LV mass/body weight: 1.7-fold increase, fractional shortening: 54% decrease, P &lt; 0.05), but not in mice receiving AZ10606120. Ang II-induced atrial natriuretic peptide (Nppa/Rps16: 7-fold, P &lt; 0.001) and α-skeletal actin 1 expression (Acta1/Rps16: 6-fold, P &lt; 0.001) tended to be further increased in P2rx7-/- mice (Nppa/Rps16: 14-fold and Acta1/Rps16: 12-fold), but not in AZ10606120-treated mice. Ang II-induced myosin heavy chain 7B (14-fold, P &lt; 0.05) was unaffected by P2rx7 knockout or P2RX7 antagonism. Ang II caused a 1.5-fold increase in transforming growth factor β; 1 only in P2rx7-/- mice (P &lt; 0.05). Conclusion: Ang II-induced LV hypertrophy and dysfunction were exaggerated by P2rx7 knockout but were not affected by P2RX7 pharmacologic blockade.