bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 18950: Invasive Electrophysiology Study has Higher Sensitivity and Specificity for Sudden Cardiac Death in Patients with Congenital Heart Disease than those with Structurally Normal Hearts
Authors: Patel Jyoti K , Bonney William , Vetter Victoria L , Iyer V. Ramesh
Published: April 2024

Introduction:
The use of electrophysiology study (EPS) in pediatric and congenital heart disease (CHD) patients to identify at risk subjects for sudden cardiac death (SCD) and implantable cardiac defibrillator (ICD) is often debated.

Objectives:
We assessed the hypothesis that EPS was more predictive for SCD or appropriate ICD discharge in patients with CHD compared to those with structurally normal hearts.

Methods:
A 15 year retrospective database review was performed for subjects undergoing EPS risk stratification for SCD. Positive EPS was defined as inducible sustained ventricular tachycardia or fibrillation by programmed stimulation. Data included demographics, EPS indications, outcome of EPS, ICD complications, and follow up SCD or ICD discharge. The primary endpoint was SCD or appropriate ICD discharge.

Results:
The study included169 subjects with mean age of 19.1 ± 7.8 years, mean follow up after EPS of 5.8 ± 4.3 years. Of these, 50 subjects (30%) had positive EPS, with ICDs subsequently placed in 28 (56%). There were 119 subjects (70%) with negative EPS, and ICDs were placed in 9 (7%). There were 85 subjects (50%) with CHD. There were no SCDs in either group. During follow-up, 10 of 37 subjects (24%) with ICDs had appropriate discharges (6 with CHD and 4 without CHD). Device related complications including recalls were seen in 21 of 37 patients (57%). The ICD shock rate, sensitivity and specificity of EPS are shown in the Table. Sub group analysis of right heart obstruction CHD lesions (n=44) showed similar results between these patients and all CHD patients (Table).

Conclusions:
The use of diagnostic EPS has a higher sensitivity and specificity for appropriate ICD discharge in pediatric patients with CHD compared to those with structurally normal hearts.
Abstract 18960: Ciliary Neurotrophic Factor Increases the Angiogenic Properties of Human Pluripotent Stem Cell Derived Neuropilin-1+ CD34+ Nascent Endothelial Cells Via a JAK2 Dependent Pathway
Authors: Lang Jennifer K , Sim Fraser J , Cimato Thomas R
Published: April 2024

Pluripotent stem cells are a model to identify novel regulators of angiogenesis. Previously, we showed that Neuropilin-1 (NRP1) CD34- cells were vascular precursors. Subsequently, genomic analysis revealed that NRP1+ CD34+ cells had transcript content consistent with nascent endothelium, and unique growth factor receptors that may be exploited to modulate their angiogenic properties. The objectives of our study was to verify that NRP1+ CD34+ cells form endothelium, and determine the function of the Ciliary Neurotrophic Factor (CNTF) Receptor and its downstream kinase Jak2 in angiogenesis.

Methods and Results:
Human induced pluripotent stem cells (hiPSCs) were differentiated as embyroid bodies and NRP1+ CD34+ nascent endothelial cells were sorted. NRP1+ CD34+ cells readily formed sheets of endothelium expressing VE-Cadherin, CD146, PECAM, and eNOS, absorbed acetylated LDL, and formed tubule networks in Matrigel. These features confirmed their endothelial properties. Here we show that CNTF promotes angiogenic sprouting of NRP1+ CD34+ cells via a Jak2 dependent mechanism. RT-PCR analysis of NRP1+ CD34+ transcripts showed a significant (> 5 fold) increase in the growth factor receptor CNTFR, and the downstream signaling partners Jak2, Stat5A and Stat6 versus undifferentiated hiPSCs. CNTF increased the length of endothelial tubules in Matrigel 44±7.3% vs. no CNTF (p≤0.05), while inhibition of JAK2 in the presence of CNTF blocked the effect of CNTF.

Conclusions:
NRP1+ CD34+ cells derived from human pluripotent stem cells readily form endothelium, and their angiogenic properties can be augmented by activation of a novel CNTFR-Jak2 mediated pathway. Collectively, the findings confirm that NRP1+ CD34+ cells are a nascent endothelial cell, and identify a novel growth factor signaling pathway involved in angiogenesis, suggesting a role for CNTF in promotion of angiogenesis in therapy for vascular diseases.
Abstract 18979: Early Termination of Adjuvant Trastuzumab Associated with Cardiovascular Events in Older Women with Breast Cancer
Authors: Chen Jersey , Long Jessica , Hurria Arti , Owusu Cynthia , Steingart Richard , Gross Cary
Published: April 2024

Background:
Biologic therapies for breast cancer such as trastuzumab, (i.e. Herceptin© [H]) increase risk of cardiovascular (CV) events such as heart failure (HF) in clinical trials. However, it is unknown how often H therapy is terminated early (i.e. < 1yr), and which CV complications are associated with early termination.

Methods:
Using Medicare data linked with SEER cancer registry data from 2000 through 2007, we identified women age 67-94 with stage I-III breast cancer who started H within 90 days of completing adjuvant chemotherapy. Completion of H was defined as >=9 months of continuous H treatments with no delay between H treatments >3 months. We assessed factors contributing to completion of H including age, race, cancer characteristics, and comorbidities. CV events occurring +/- 3 months from last H treatment were ascertained from billing claims.

Results:
The sample included 294 older women (mean age 71.5 years) without CV events within the year prior to initiation of H. Approximately 79.3% (233) patients completed at least 9 months of H. Early termination of H was significantly associated with any CV complications (27.9% v 8.6%, p<.001), particularly HF or cardiomyopathy (6.6% v 0.4%, p<.001), p=.02) and atrial fibrillation [AF] (8.2% v 2.1%, p=0.02)

Conclusion:
Early termination of H is common among older women, and associated with higher rates of cardiovascular events. Preventing CV complications such as AF may improve survival in patients with breast cancer by increasing the likelihood of receiving the recommended course of H therapy. Funding(This research has received full or partial funding support from the American Heart Association)
Abstract 19043: Rantes Dependent T Cell Recruitment into Perivascular Adipose Tissue n Angiotensin II Dependent Hypertension - Implications for Vascular Dysfunction and Blood Pressure Regulation
Authors: Mikolajczyk Tomasz , Nosalski Ryszard , Skiba Dominik , Korbut Ryszard , Harrison David , Guzik Tomasz
Published: April 2024

Hypertension (HT) is associated with T cell activation and their recruitment into perivascular adipose tissue (PVAT). We hypothesized that RANTES chemokine is critical for T cell recruitment into PVAT and therefore plays a role in hypertension and vascular dysfunction. Thus, we cytometrically analysed numbers and phenotype of T cells infiltrating perivascular adipose tissue in C57Bl6/J and RANTES -/- mice infused for 14 days with (angiotensin II (490mg/kg/d).

Results:
AngII infusion caused increased PVAT leukocyte (CD45+) infiltration (2407±108 vs 654±70 cells/mg; p<0.01). This increase was particularly evident for CD3+ T cells (730±38 vs 140±23 cells/mg; p<0.01). Infiltration of CD4+ was higher than that of CD8+ (337±11 vs 229±11 cells/mg), but an infiltration with CD3+CD4-CD8- T cells (DN; constituting only 3-5% in blood) was particularly pronounced in pvAT (98±14 vs 23±3 cells/mg; p<0.05). Expression of RANTES chemokine receptor CCR5 on PVAT T cells was increased in HT (24±09% vs 17±08%; p<0.01) with highest prevalence on DN T cells and lowest on CD8+ (31±0.8% and 17±1.4%, respectively). RANTES-/- mice showed significantly decreased T cell infiltration of PVAT (394±80 vs 730±38, p<0.05) which was observed in all T cell subsets suggesting that RANTES is essential for vascular T cell homing. In particular reduced content of CCR5 in T cells infiltrating perivascular adipose tissue was observed (18±1.3% vs 24±09%; p<0.01). This was associated with protection of RANTES -/- from endothelial dysfunction measured as acetylocholine-induced NO dependent relaxations (p<0.05 by repeated measures ANOVA). In spite of that, RANTES -/- mice still developed severe hypertension (14 day:171±8.6 mmHg vs 154±3.9 in C57Bl6/J). Importantly, we observed that angiotensin II infusion caused increased PVAT infiltration with IL-17+CD4+ cells (1.3±0.3% vs 0.2±0.2%; p<0.05). This was further exacerbated in RANTES -/- mice (1.7±05% vs 1.3±0.3%).

Conclusions:
In hypertension, RANTES is crucial for vascular T cell homing and is a major regulator of perivascular inflammation and endothelial dysfunction. Persistent augmented presence of Th17 cells may be associated with increased blood pressure in RANTES-/-, after Ang II administration.
Abstract 19046: RBC-Macrophage Inflammatory Axis: Potential Role in Atherosclerosis
Authors: Srinivasan Ramprasad , Coyle Danielle , Batra Neil , Blanco Victor , Tong Wilson , Palascak Mary , Franco Robert S , Chatterjee Tapan , Hui David Y , Davidson W. Sean , Aronow Bruce J , Ozhegov Evgeny , Manka David , Peairs Abigail , Blomkalns Andra , Weintraub Neal L , Bogdanov Vladimir Y
Published: April 2024

Background:
Red blood cells (RBC) modulate vasoreactivity, serve as a reservoir for chemokines via binding to Duffy antigen receptor for chemokines (DARC), and contribute to the pathology of atherosclerotic plaque rupture, suggesting a broad role in vascular pathophysiology. High fat diet (HFD) is known to negatively impact vascular function and modify RBC membrane composition, but how this affects RBC chemokine binding, and interaction with macrophages and blood vessels, is unknown.

Methods and Results:
RBC from C57BL/6J mice fed chow diet (chow RBC) or 60% HFD (HFD RBC) for 16 weeks were collected and studied in vitro and in vivo. Reactive oxygen species (DCFH fluorescence) and phosphatidylserine externalization (annexin V binding), a potential signal for RBC phagocytosis, were increased ~1.5 fold (p<0.05) in HFD RBC compared to chow RBC. HFD RBC released ~1.5 fold more monocyte chemoattractant protein-1 (MCP-1) (p<0.05) compared to chow RBC upon addition of heparin to disrupt DARC binding. In a transwell system, HFD RBC, as compared with chow RBC, produced a significant increase in the migration of thioglycollate-elicited macrophages through an endothelial monolayer (p<0.05). Incubation of HFD RBC with murine macrophages demonstrated a ~1.5 fold (p<0.05) increase in phagocytosis compared to chow RBC; upon their internalization by macrophages, HFD RBC more potently upregulated transcription of major pro-inflammatory chemokines Il-1b, Ccl3, and Cxcl2. As compared with chow RBC, exposure of murine aortic segments to HFD RBC under orbital shear conditions led to enhanced endothelial activation as evidenced by increased adhesion of labeled murine macrophages to the aortic endothelium (p<0.05). Finally, when labeled and injected in vivo, HFD RBC exhibited a ~3 fold (p<0.05) increase in splenic phagocytosis as compared with chow RBC.

Conclusion:

HFD profoundly impact RBC biology, inducing oxidative stress, altering membrane phospholipid display, and increasing chemokine release, phagocytosis by macrophages, and macrophage-blood vessel interactions. These novel findings suggest that RBC may play an important role in transducing vascular inflammation, and thus contributing to atherosclerosis, during HFD.
Abstract 19085: Cross-bridge Activation at Diastolic Calcium Levels in Human Myocardium
Authors: Palmer Brad , Donaldson Cameron , Meyer Markus , VanBuren Peter , Zile Michael , LeWinter Martin
Published: April 2024

Tropomyosin is positioned on actin in dynamic equilibrium as a function of free calcium concentration. However, it is estimated that ∼5% of the myosin binding sites on actin are exposed at low calcium levels (e.g. pCa 8) raising the possibility of myosin cross-bridge formation at diastolic calcium levels. We tested this hypothesis in detergent-treated (skinned) strips dissected from epicardial biopsies obtained from male patients during coronary bypass grafting. Patients (n=15) had normal left ventricular (LV) ejection fraction and wall motion. Eight control (C) patients had neither hypertension (HTN) nor diabetes mellitus. Seven patients had HTN and concentric remodeling with increased LV wall thickness/radius ratio. Western blot analysis of skinning supernatant revealed no loss of tropomyosin or troponin-I that would implicate loss of normal thin filament regulation during the skinning process. Myofilament calcium sensitivity at sarcomere length 2.2 μm was similar between C and HTN (pCa
50
6.07±0.07 vs 6.06±0.04). Tension at pCa 8 was similar between C and HTN (4.26±0.52 vs 4.30±0.51 mN.mm
-2
), but was significantly reduced by application the cross-bridge inhibitor 2,3-butanedione monoximine (BDM) (2.15±0.24 vs 3.01±0.40 mN.mm
-2
, p<0.05). The higher tension in HTN with BDM reflects a greater inherent stiffness in HTN independent of cross-bridges. We then used sinusoidal length perturbations (0.125-250 Hz) to detect the detachment rate of cycling cross-bridges. In both C and HTN strips, frequency-dependent viscoelastic characteristics of cycling cross-bridges were apparent at pCa 8 and abolished with BDM. At pCa 8 cross-bridge detachment rate was significantly greater in C than HTN (106.1±12.5 vs 74.6±9.3 s
-1
, p<0.05). These results indicate that there are cycling cross-bridges in normal and concentrically remodeled human myocardium at diastolic calcium levels that contribute to diastolic tension. Furthermore, the rate of cross-bridge detachment under relaxed conditions is slower in concentrically remodeled myocardium from HTN compared with C patients. The presence and lifetime of cross-bridges formed in addition to cross-bridge independent stiffness must be considered as significant contributors to diastolic dysfunction in HTN.
Abstract 19088: Differential Mobilization of Progenitor Cells in Smoker and Non-smoker Patients with Acute Myocardial Infarction : Insights from the Bonami Biology Sub-study
Authors: Lamirault Guillaume , Susen Sophie , Forest Virginie , Hemont Caroline , Parini Angelo , Le Corvoisier Philippe , Piot Christophe , Richard Marie-Jeanne , Delasalle Béatrice , Rouard Hélène , Sportouch Catherine , Persoons Virginie , Van Belle Eric , Van Belle Eric , Roncalli Jérôme , Lemarchand Patricia
Published: April 2024

Introduction:
Although autologous bone marrow cell (BMC) therapy has emerged as a promising option to treat acute myocardial infarction (AMI), randomized trials reported mixed results. This may be explained in part by great variability in the functionality of BMCs retrieved from patients with risk factors of atherosclerosis.

Hypothesis:
We hypothesized that active smoking may alter bone marrow-derived progenitor cells number and functionality in patients with AMI. The aim of the current study was to investigate the characteristics of BMCs in active smokers and non-smokers with AMI and their potential impact on BMC therapy efficacy.

Methods:
We compared progenitor cells in bone marrow and blood samples from 54 active smokers and 47 non-smokers with AMI enrolled in the BONAMI cell therapy trial.

Results:
White bone marrow cell number per microliter and CD45dimCD34+ cell number were higher in active smokers (p=0.001, p=0.03, respectively). In marked contrast, in active smokers there was a decrease of both bone marrow and blood endothelial progenitor CD45dimCD34+KDR+ cells (EPCs) expressed as their percentage per 10
5
WC (p=0.005, p=0.04, respectively). Importantly, a multivariate linear regression analysis including CV risk factors that were significantly different between non- and active smokers, confirmed the association between active smoking and a lower EPC number per 10
5
WC in both blood (p=0.04) and bone marrow (p=0.04) Furthermore, in non-smokers not receiving BMC therapy, there were positive correlations between circulating EPC levels and the decrease in infarction defect size (p=0.02) and viability improvement (p=0.02) measured by SPECT at 3 month post-MI. This association was not observed in active smokers and in patients receiving BMC therapy.

Conclusion:
These data suggest that circulating EPCs play an important role in cardiac repair post-MI in non-smokers but not in active smokers. This discrepancy may be explained by a lack of activation of the endothelial cell lineage, and of blood mobilization of EPCs in active smokers after AMI. Future studies are warranted to understand critical features of progenitor cell preparations and of patients with AMI that are predictive of a favorable response to cell transfer.
Abstract 19119: National Trends and Acute In-Hospital Outcomes for Pericardiocentesis and Pericardiotomy in the United States
Authors: Hermany Paul L , Zack Chad J , McClurken James B , Bove Alfred , Bashir Riyaz
Published: April 2024

Background:
The national utilization rates and trends of pericardiocentesis and pericardiotomy are unknown. The objective of this observational study was to characterize the trends and in-hospital mortality of pericardiocentesis and pericardiotomy in the United States.

Methods:
The Nationwide Inpatient Sample (NIS) database was used to identify patients who underwent pericardiocentesis or pericardiotomy from 2005 to 2009. We evaluated their in-hospital mortality and used risk adjusted logistic regression to analyze the predictors of adverse outcomes including death.

Results:
A total of 131,945 patients underwent either pericardiocentesis or pericardiotomy during these five years. Pericardiocentesis was done in 49,854(37.8%) and pericardiotomy was done in 82,090 (62.2%). The per annum pericardiocentesis rate increased from 9,171 in 2005 to 11,088 in 2009 (20.9% increase) whereas the pericardiotomy rates were essentially the same during the study period. The risk adjusted in-hospital mortality was significantly higher in the pericardiocentesis group than in the pericardiotomy group (15.5% versus 10.3% p<0.001).

Conclusion:
In this observational study, we found that during the five-year study period the rates of pericardiocentesis significantly increased while pericardiotomy rates remained unchanged. The risk adjusted in-hospital mortality was significantly higher with pericardiocentesis than pericardiotomy.
Abstract 19144: New Ischemic Stroke and Outcomes with Vorapaxar vs. Placebo: Results from TRA 2°P-TIMI 50 Trial
Authors: Bonaca Marc P , Scirica Benjamin M , Braunwald Eugene , Wiviott Stephen D , Goto Shinya , Nilsen Dennis , Bonarjee Vernon , Murphy Sabina A , Morrow David A
Published: April 2024

Vorapaxar is a potent platelet inhibitor that reduces thrombotic events in stable patients with a history of myocardial infarction (MI) or peripheral artery disease (PAD); however, this benefit is offset by increased bleeding including intracranial hemorrhage particularly in patients with established cerebrovascular disease (CVD). We investigated the outcomes in patients with MI or PAD experiencing a first ischemic stroke on vorapaxar.

METHODS: The TRA2P-TIMI 50 trial was a randomized, double-blind, placebo controlled trial of vorapaxar 2.5 mg daily in 26,449 patients with established atherosclerotic vascular disease. Patients were stratified at randomization by their qualifying atherosclerotic condition (MI, PAD, or CVD). After two years, the Data and Safety Monitoring Board recommended discontinuation of study treatment in those with prior stroke or incident stroke. We evaluated the risk of new ischemic stroke outcomes with vorapaxar in 20,170 patients with MI or PAD but no history of CVD.

RESULTS: In patients with MI or PAD and no history of CVD, vorapaxar significantly reduced ischemic stroke (HR 0.57, 95% CI 0.43 - 0.75, p<0.001)(Figure A). Overall there were numerically fewer hemorrhagic conversions in patients treated with vorapaxar who suffered a first ischemic stroke. The risk of hemorrhagic conversion (HR 1.19, 95% CI 0.49 - 2.91, p=0.70) or death (HR 1.09, 95% CI 0.57 - 2.07, p=0.79) during follow up was not significantly increased with vorapaxar. Although hemorrohagic stroke was increased (HR 2.78, 95% CI 1.00- 7.73, p=0.049) overall stroke was significantly reduced (HR 0.68, 95% CI 0.52 - 0.8, p=0.005) with vorapaxar (Figure B).

CONCLUSIONS: Vorapaxar reduces thrombotic events including ischemic stroke in stable patients with MI or PAD. There is no significant increase in the risk of hemorrhagic conversion or death in MI or PAD patients who experience a first ischemic stroke on vorapaxar. Hemorrhagic stroke is increased but all stroke is reduced.
Abstract 19208: Higher Cornell Product and QTc on Exercise Stress Testing are Correlated with Lower Cardiac MRI T1 Times in Hypertrophic Cardiomyopathy
Authors: Saha Sudip , Corona-Villalobos Celia , Zimmerman Stefan , Noureldin Radwa , Kamel Ihab , Bluemke David , Abraham Theodore , Abraham M. Roselle
Published: April 2024

Hypertrophic cardiomyopathy (HCM) is characterized by ventricular hypertrophy, myocyte disarray and interstitial fibrosis which result in arrhythmias, sudden death and heart failure. Studies have shown that the resting EKG can be used to predict abnormalities on contrast enhanced cardiac MRIs. However, studies correlating changes seen in the EKG during exercise and measurements on MRIs in the HCM population have not been studied. The exercise state is clinically relevant for patients with HCM and exercise stress testing is an economical tool that is often abnormal in HCM patients. We assessed the hypothesis that during the exercise state changes in various EKG parameters such as the Cornell product, for example, would correlate with lower T1 times on contrast enhanced MRIs. One hundred and sixty three patients (67% male) were evaluated fulfilling standard HCM criteria and clinical history was obtained. EKGs from Bruce protocol treadmill stress testing were independently analyzed for heart rate, QRS duration, LVH criteria including Sokolow-Lyon and Cornell product, ST changes, T wave inversions, and strain pattern. Contrast enhanced MRIs were performed and T1 mapping was analyzed independently. As shown in Table 1, compared to the rest state, peak exercise EKGs showed higher Cornell product, QTc, QRS duration, greater presence of strain pattern, and non-specific ST depressions and T wave inversions (p < 0.001 in all groups). The Cornell product (r = -0.71 for rest, r = -0.86 for exercise state) and QTc (r = -0.62 for rest, r = -0.74 for exercise) were correlated with lower T1 times. In conclusion, the novel findings of this study are that abnormalities in parameters such as the Cornell product or QTc correlate with lower T1 times on MRI, especially in the exercise state. Lower T1 times are associated with greater fibrosis and abnormalities in repolarization or conduction (as seen in EKGs during the exercise state) could indicate a subpopulation of HCM patients at greater risk.
Abstract 19255: A Role for Mitochondria in Triggered Activity from Cardiomyocytes with Reduced Sarcoplasmic Reticulum Calcium Release
Authors: Xie An , Kapoor Nidhi , Liu Hong , Bare Dan , Gu Lianzhi , Boheler Kenneth R , Banach Kathrin , Dudley Samuel C
Published: April 2024

Introduction:
A prominent feature of systolic heart failure is the reduction of Ca2+ induced Ca2+ release from sacroplasimic reticulum (SR). Moreover, patients with heart failure are at high risk of arrhythmic sudden cardiac death. Hypothesis: The basis for increased arrhythmic risk with reduced SR Ca2+ release was investigated using embryonic stem cell derived ventricular-like cardiomyocytes (CMs) deficient for the expression of the ryanodine receptor (RYR-/-).

Methods:
Action potentials (APs) and L-type Ca2+ currents were recorded in the perforated current-clamp and whole cell voltage-clamp respectively. Changes in [Ca2+]i were determined by confocal imaging of Fluo-4/AM ESCs. APs were recorded from CMs differentiated for 19 days.

Results:
Compared with wild type CMs, L-type Ca2+ channels showed less current density and slightly slower activation/inactivation kinetics in RyR-/- CMs. AP and Ca2+ transient frequency were decreased. Ca2+ transient amplitudes were smaller in RyR-/- CMs and had prolonged transient duration at 50% amplitude. Ca2+ transients are comparable to those of WT cells after SR depletion by caffeine, indicating that the SR in RyR-/- CMs did not contribute significantly to Ca2+ release or removal. Despite a shorter AP duration at 90% repolarization (APD90: 187.7 ± 13.8 ms vs. 274.3 ± 36.3 ms), RyR-/- ventricular-like CMs displayed more delayed after-depolarizations (DADs, 75% vs. 0%, p<0.05) than WT CMs. Arrhythmia-inducing Ca2+ leak in RyR-/- CMs can come from IP3R mediated Ca2+ release or from mitochondrial Ca2+. In the presence of the IP3R blocker 2-APB, AP frequency decreased (from 1.3±0.1 to 0.3±0.1 Hz) supporting its role in pacemaker activity, but DADs remained. In the absence of [Ca2+]o, an increase in SR load after a caffeine-induced depletion of the SR indicated Ca2+ transfer from the mitochondria to the SR. Application of the mitochondrial NCX blocker (CGP) suppressed this transfer in WT CMs. Block of the mitochondrial Ca2+ uptake (Ru360) prevented DADs in RyR-/- CMs. Conversely application of PPT, an activator of the mitochondrial Ca2+ uniporter, enhanced DADs in RyR-/- ESCs.

Conclusions:
DADs may occur in the presence of reduced SR Ca2+ release. DADs in RyR-/- CMs depends on mitochondrial Ca2+ flux.
Abstract 19257: TRPC3 and IP3 Regulate Angiotensin II Induced Ca2+ Dependent Arrhythmias in Mouse and Human Cardiomyocytes
Authors: Sacherer Michael , Ljubojevic Senka , Stiegler Philipp , Sereinigg Michael , Pieske Burkert , Heinzel Frank
Published: April 2024

Angiotensin II (ATII) is associated with cardiac remodeling, heart failure and arrhythmia. In cardiomyocytes (CM), ATII signals primarily via the Gq-coupled ATII receptor type 1 (AT1), phospholipase C signaling pathway including IP3-mediated Ca release and diacylglycerol activation of protein kinase C. Diastolic Ca release from the sarcomplasmic reticulum (SR) triggers arrhythmogenic inward current via the sarcolemmal Na-Ca-exchanger (NCX). Recent evidence suggests that TRPC3 channels and NCX may also be regulated by ATII contributing to arrhythmogenity. We investigated the mechanisms of Ca-mediated cellular arrhythmias induced by ATII. In CM from murine or human non-failing left ventricle, [Ca] transients (Fluo4-AM) during 1 Hz, as well as SR Ca load (caffeine), SR Ca leak (Ca spark frequency,SparkF) and arrhythmic (arrh) action potentials (as synchronized diastolic Ca release) during prolonged diastole were quantified in confocal images. Action potentials (AP) were recorded (current clamp) in a subset of cells. ATII (100 nM,20 min) in combination with IP3-inhibitor 2-ABP (3 µM) or TRPC3-inhibitor Pyr3 (10 µM), or ouabain (100 nM) were used in parallel experiments. In mouse CM ATII increased [Ca] transient amplitude (F/F0: 4.1±0.3 vs. 2.7±0.2 in CTRL). ATII also induced Ca sparks (SparkF (s-1*pL-1): 277±28 vs. 48±20) and arrhAP (0.77±0.12 vs. 0.03±0.01arrhAP*s-1) despite unchanged SR [Ca]. ATII induced significantly more arrhAP than ouabain (0.06±0.02) despite similarly increased SparkF (ouabain: 284±44). ATII tended to increase AP duration from 53±6 to 92±34 ms (APD90; P=0.1). 2-APB significantly reduced ATII -induced Ca sparks and arrhAP. In CM matched for SR Ca leak (SparkF), 2-APB significantly reduced - and Pyr3 abolished ATII-induced arrhAP. ATII was also arrhythmogenic in human non-failing CM (SparkF: 407±93 vs. 90±23 in CTRL;cells with arrhAP: 6/10 vs. 2/11; p<0.05). Pyr3 also effectively reduced AT-II induced arrhythmogenity in human CM (SparkF: 101±21; 0/7 cells with arrhAP; both P<0.05).

Conclusion:
ATII facilitates Ca-dependent arrhythmias by mechanisms beyond an increase in SR Ca leak in mouse and human CM. TRPC3-channels promote the arrhythmogenity of diastolic SR Ca release in the presence of ATII.
Abstract 19286: Rhythm Results Following Surgical Ablation- How Should it Be Reported?
Authors: Ad Niv , Hunt Sharon , Henry Linda
Published: April 2024

Background:
The improved understanding of the pathophysiology of atrial fibrillation (AF) and the non-pharmacological approaches to treat AF provided higher success. There is a lack of uniformity and agreement in the best way to report rhythm outcomes. The study purpose is to explore the impact of longitudinal follow up on understanding the ongoing atrial arrhythmia burden compared with the static time points recommended by the Heart Rhythm Society (HRS) guidelines

Methods:
All patients undergoing AF surgical ablation at our institution (n=690) are followed prospectively thru our AF registry. Rhythm verified by EKG and 24 hour holter. Patients selected for this study had to be at risk for failure at least 2 years following the procedure (n=464). The HRS definition of failure determined rhythm. Rhythm is reported per HRS guidelines/ “longitudinal rate (LR)” defined as the need for additional interventions to keep patients in SR (ablations and cardioversions).

Results:
Per HRS guidelines, patients in SR at discharge was 388/464 (84%) ; 6 months 359/400 (90%) with 281/370 (76%) off antiarrhythmic drugs (AAD) ; 12 months 356/397 (90%) with 312/386 (81%) off AAD, 24 months 268/307 (87%) with 231/301 (77%) off AAD. Success per LR at 6 months 315/400 (79%), 12 months 299/397 (75%) patients and 24 months 217/301 (71%). The freedom from AF and interventions was lower at each period compared to the HRS rate. Of the patients off AAD, 12% (n=26) required an intervention suggesting that only pharmacological methods were required to maintain SR not captured per LR (Figure).

Conclusion:
Surgical ablation for AF results in acceptable rhythm outcomes over time. Reporting of rhythm status only at static time points does not provide the continuous burden of atrial arrhythmia and need for follow-up pharmacological and non-pharmacological interventions. We recommend patients should be followed using the two methodologies to improve understanding of the rhythm results following ablation for AF.
Abstract 19295: Genetic Deletion of E2F1 Protects Myocardium from Ischemic Injury by Upregulating Angiogenic Growth Factors
Authors: Wu Min , Zhou Junlan , Cheng Min , Boriboun Chan , Biyashev Dauren , Wang Hong , Kishore Raj , Losordo Douglas , Qin Gangjian
Published: April 2024

Background
: The E2F family of transcription factors, with eight members identified, are involved in the regulation of a variety of cellular functions, including cell growth, differentiation, metabolism, and survival; however, the specific roles of individual members in the cardiovascular system have not been carefully characterized. Here, we investigated the potential role of E2F1 in cardiac neovascularization.

Methods and Results
: Myocardial infarction (MI) was induced in WT and E2F1
-/-
mice. Compared to observations in WT mice, cardiac function, capillary density, and endothelial-cell (EC) proliferation were greater (P<0.01), infarct sizes were smaller (P<0.01), apoptotic ECs were less common (P<0.01); border-zone levels of vascular endothelial-cell growth factor (VEGF) (P<0.05) and placental growth factor (PlGF) (P<0.01) were higher; and border-zone p53 levels were lower (P<0.01); in E2F1
-/-
mice. Blockade of VEGF receptor 2 (VEGFR2) signaling with the selective inhibitor SU5416 or with the VEGFR2-blocking antibody DC101 abolished the differences between E2F1
-/-
mice and WT mice in cardiac function, infarct size, capillary density, EC proliferation, and EC apoptosis. Hypoxia-induced VEGF and PlGF upregulation was significantly greater in E2F1
-/-
than in WT cardiac fibroblasts, and E2F1 overexpression suppressed PlGF upregulation in both WT and p53
-/-
cells; however, VEGF upregulation was suppressed only in WT cells. E2F1 interacted with and stabilized p53 under hypoxic conditions, and both E2F1:p53 binding and the E2F1-induced suppression of VEGF promoter activity were absent in cells that expressed an N-terminally truncated E2F1 mutant.

Conclusions
: E2F1 limits cardiac neovascularization and functional recovery after MI by suppressing VEGF and PlGF upregulation through p53-dependent and -independent mechanisms, respectively.
Abstract 19296: In-Stent Neoatherosclerosis: Are First Generation Drug Eluting Stents Different Than Bare Metal Stents? An Optical Coherence Tomography Study
Authors: Karanasos Antonios , Witberg Karen , Ligthart Jurgen , van Geuns Robert-Jan , Daemen Joost , Bruining Nico , van Soest Gijs , Zijlstra Felix , Toutouzas Konstantinos , Regar Evelyn
Published: April 2024

Purpose: In-stent neoatherosclerosis has been recognised in pathologic specimens of bare metal stents (BMS), and recently in first generation drug eluting stents (1st-DES) as well. However, in vivo data are scarce. By optical coherence tomography (OCT), we investigated the incidence and morphological characteristics of neoatherosclerosis (NA) very late after BMS or 1st-DES implantation.

Methods: From 1/1/2007 to 31/1/2012, 52 patients from two institutions underwent >24 months follow-up OCT assessment of a BMS or a 1st-DES (13 BMS - 39 1st-DES). NA was characterized using criteria for native atherosclerosis.

Results: Differences between BMS and 1st-DES are presented in the table. BMS had longer follow-up interval but no differences in clinical presentation at follow-up. No significant differences were evident in the incidence of NA, neointimal rupture, lipid content, neovascularization or macrophage infiltration between BMS and 1st-DES. There was however a trend for lower fibrous cap thickness (FCT) and for higher calcification in BMS (FCT: 51±31μ m vs. 92±59μ m, p=0.057; calcifications: 46.2% vs. 15.4%, p=0.051). 1st-DES with neoatherosclerosis had longer interval from implantation compared to 1st-DES with homogeneous coverage [Median 71 months (range 25-130) vs. 57 months (24-68), p<0.05], but there was no difference for BMS with or without neoatherosclerosis [Median 125 months (range 90-201) vs. 168 months (132-168), p=0.54].

Conclusions: The incidence and morphological characteristics of NA are similar between 1st-DES and BMS of more prolonged follow-up. Our findings suggest a time-dependent pattern in the incidence of NA in 1st-DES with 2-11 years follow-up.
Abstract 19297: Cardiac Specific Deletion of Mcl-1 Leads to Impaired Autophagy and Rapid Development of Heart Failure
Authors: Thomas Robert L , Lee Youngil , Roberts David , Hanna Rita , Zhang Xiaoxue , Miyamoto Shigeki , Sussman Mark A , Gustafsson Åsa B
Published: April 2024

Mcl-1 is an anti-apoptotic Bcl-2 protein which is expressed at high levels in the heart compared to other anti-apoptotic Bcl-2 proteins. However, very little is known with respect to how Mcl-1 regulates cell survival in cardiomyocytes. To investigate the functional role of Mcl-1 in the heart, we used a loxP/α-MHC-Cre-recombinase system to generate inducible, cardiomyocyte-specific Mcl-1 knockout mice. Mcl-1 deletion led to rapid contractile dysfunction, cardiac hypertrophy, and interstitial fibrosis in the absence of stress. Surprisingly, loss of Mcl-1 did not activate apoptosis. Instead, Mcl-1 deficiency led to necrotic cell death characterized by mitochondrial permeability transition pore (mPTP) opening, mitochondrial swelling, and cellular rupture. To clarify how mPTP opening and necrosis contribute to heart failure in Mcl-1-/- mice, we generated Mcl-1/Cyclophilin D (CypD) double knockouts. CypD is an essential component of the mPTP, and CypD deficiency has been shown to reduce cardiac necrosis. CypD deletion significantly delayed development of heart failure in Mcl-1-/- mice, but did not rescue the phenotype. Although autophagy is an important cellular quality control mechanism, electron microscopy revealed no autophagosome formation in Mcl-1-/- cardiomyocytes. Further analysis revealed that loss of Mcl-1 led to impaired basal autophagic flux. Western blot analysis for autophagy proteins revealed reduced LC3II/I ratios and accumulation of p62 in Mcl-1-/- hearts. Chloroquine injection, which inhibits the fusion between autophagosomes and lysosomes, led to accumulation of LC3II and p62 in WT hearts but not in Mcl-1-/- hearts. To investigate whether autophagy could be induced in Mcl-1-/- hearts, we subjected mice to acute exercise. Autophagy was rapidly enhanced in wild type hearts after 80 minutes of swimming, but no change in autophagy occurred in Mcl-1-/- hearts. Conversely, adenoviral overexpression of Mcl-1 in rat neonatal cardiomyocytes led to increased LC3 processing and autophagy. These data suggest that, in addition to its anti-apoptotic role, Mcl-1 is essential in initiating autophagy in cardiomyocytes. Increased understanding of Mcl-1 mechanisms in the myocardium may provide new therapeutic avenues for heart disease.
Abstract 19302: Area Strain for the Assessment of Myocardial Infarction Scar Size by Ultrasound 3D Speckle Tracking: Validation with Late Gadolinium Enhancement Magnetic Resonance Imaging
Authors: de Marchi Stefano F , Hopp Einar , Urheim Stig , Svendsmark Rolf , Hervold Anders , Murbræch Klaus , Massey Richard J , Remme Espen W , Hol Per K , Aakhus Svend
Published: April 2024

Background:
Myocardial infarction scar size (ISS) is an important predictor of mortality, but accurate quantitative echocardiographic methods to determine ISS are lacking. We developed a new functional imaging method based on geometric analysis of 3D meshgrid-representations of the left ventricle (LV) derived from ultrasound 3D speckle tracking. The study was performed to validate our method for the quantitative assessment of ISS.

Methods:
3D full volume echocardiographic clips and late gadolinium enhancement magnetic resonance images (LGE-MRI) were acquired in 10 patients three months after acute myocardial infarction. ISS was determined from LGE-MRI images. 3D speckle tracking was performed on EchoPac (GE Vingmed), and LV meshgrids were analyzed offline using our novel software. Area strain, a parameter of regional wall thickening, was computed and displayed in 336 LV regions (figure). Infarction zone was delineated by a blinded observer as the region with reduced end-systolic area strain. The size of the delineated zone was calculated relative to the total LV surface.

Results:
ISS in LGE-MRI ranged from 0 to 38% (median 18.5%). ISS closely correlated between echocardiography and LGE-MRI (figure). Bias and S.D. of bias of our method, as assessed from two different echocardiographic clips in all patient, was -1.94% and 5.01%, respectively.

Conclusions:
The total size of reduced end-systolic area strain accurately reflects ISS as assessed by LGE-MRI. Thus, functional imaging based on 3D speckle tracking has great potential for the accurate determination of myocardial infarction scar size by echocardiography.
Abstract 19321: Novel 3D Microengineered Heart Valve Construct Mimics Early Calcific Aortic Valve Disease
Authors: Hjortnaes Jesper , Camci-Unal Gulden , Lax Lilian , Kluin Jolanda , Schoen Frederick J , Khademhosseini Ali , Aikawa Elena
Published: April 2024

Objective:
In calcific aortic valve disease (CAVD), evidence suggests that pro-inflammatory cues stimulate valvular interstitial cells (VIC) to undergo phenotypic modulation to osteoblast-like cells, leading to the formation of calcific nodules. However, the exact mechanism is unknown. We aim to engineer a novel 3D tissue model of CAVD to study the pro-inflammatory mechanisms of CAVD. This model uses a microengineered construct of natural ECM polymers of the native valve that mimics the extracellular matrix (ECM) environment of native tissue.

Methods and Results:
Porcine aortic VICs were encapsulated in photocrosslinkable hydrogels comprised of hyaluronic acid and gelatin methacrylate. These cell-laden 3D constructs were cultured in control (NM) (n=3) and osteogenic media (OM) (n=3), with (n=3) and without pro-inflammatory cytokine Tumor Necrosis Factor alpha (TNFα) (10 ng/mL) for up to 21 days. VIC viability was more than 90% after 21 days in culture. In healthy valves VICs are characterized by minimally expressed α-Smooth Muscle Actin (α-SMA). Under pathological conditions, VICs differentiate into activated myofibroblasts with abundant expression of α-SMA. We showed that, when our heart valve constructs were cultured in OM, α-SMA expression gradually decreased while an increase of Runx2, a transcription factor upregulated in osteoblast-like cells, was observed. Constructs exposed to OM revealed a time-dependent induction of calcified noduli formation, where alkaline phosphatase (ALP) activity showed a peak at day 14 (d1: 0.45±0.11 vs d14: 1.96±0.11 vs d21: 0.88±0.07 U/mL (p <0.05)) and calcium deposition follows ALP activity and reaches a plateau at day 16 to day 21 (d1: 0.4 μ g/mL vs. d16 11.9 μ g/mL (p<00.5) vs d21: 10.6 μ g/mL (p >0.05)). Stimulation of heart valve constructs grown in OM with TNFα showed an increase in the amount of calcified noduli compared to without TNFα (d21: 69±7 vs 47±4 noduli (p<0.05)) and promoted Runx2 expression, suggesting a direct effect of pro-inflammatory cues on valvular calcification.

Conclusions:
Our novel
in vitro
3D heart valve model simulates events that occur during early CAVD
in vivo,
in which pro-inflammatory mechanisms play an important role. This model provides a new platform to study mechanisms of CAVD.
Abstract 19334: Exposure to Diesel Exhaust Emissions Markedly Induce Systemic Lipid Peroxidation and the Development of Dysfunctional Prooxidative and Proinflammatory HDL
Authors: Yin Fen , Lawal Akeem , Ricks Jerry , Richman Julie , Larson Tim , Navab Mohamad , Rosenfeld Michael , Araujo Jesus
Published: April 2024

Rationale:
Exposure to ambient particulate matter is associated with increased cardiovascular ischemic events and enhanced atherosclerosis, likely due in part to the promotion of systemic pro-oxidant and pro-inflammatory effects.

Objective:
The purpose of this study was to test our hypothesis that air pollutants may induce oxidative modifications of plasma lipoproteins resulting in alteration of the anti-oxidant and anti-inflammatory properties of high-density lipoproteins (HDL).

Methods and Results:
We exposed ApoE-/- and C57BL/6 wild-type male mice to diesel exhaust (DE) emissions at 200-300 µg PM2.5/m3 for two weeks, filtered air (FA) for two weeks or DE for two weeks, followed by FA for one week (DE+FA). HDL anti-oxidant capacity was assessed by a DCF-based cell fluorescence assay that evaluate the ability of HDL to inhibit LDL oxidation, determined by the level of fluorescence intensity. In the ApoE-/- background, DE and DE+FA mice significantly impaired the HDL anti-oxidant capacity in comparison with FA mice (p<0.001), as judged by almost a doubling in the level of DCF fluorescence and by a promotion rather than inhibition of oxidation. Decreased HDL anti-oxidant properties was accompanied by reduced anti-inflammatory capacity, as determined by a monocyte chemotaxis assay. The HDL anti-oxidant dysfunction correlated with decreased paraoxonase enzymatic activity, increased levels of plasma 8-isoprostanes, 12-HETE, and 13-HODE as well as liver malondialdehyde and 5-HETE levels (p< 0.05), with subsequent up-regulation of hepatic anti-oxidant genes, activation of unfolded protein response and the 5-lipoxygenase pathway. Moreover, while DE led to enhanced lipid peroxidation in the bronchoalveolar lavage fluid of both ApoE-/- and C57BL/6J mice, there were no effects of DE exposure on systemic lipid peroxidation or HDL functionality in the latter.

Conclusions:
DE emissions induced systemic pro-oxidant effects that led to the development of dysfunctional HDL in hyperlipidemic ApoE-/- mice, which might be one of the mechanisms how air pollution contributes to enhanced atherosclerosis.
Abstract 19357: The Prevalence and Significance of Aortic Root Dilation in Highly Trained Athletes: `Relevance to the Bethesda Consensus Panel Guidelines'
Authors: Sedgwick Catherine , Gati Sabiha , Papadakis Michael , Reed Matt , Zaidi Abbas , Sheikh Nabeel , Cox Andrew , Ghani Saqib , Child Anne , Sharma Sanjay
Published: April 2024

Introduction:
Studies in highly trained athletes reveal increased aortic root dimensions compared with controls. It is unclear whether aortic root dilation represents ‘athlete’s heart’ or a potential aortopathy. The Bethesda recommendations suggest that athletes with an aortic root dimension of ≥40mm should only participate in low-intensity competitive sport. This study sought to investigate the prevalence and clinical significance of aortic root dilation in nationally ranked British athletes.

Methods:
Between 2004-2012, 1160 athletes (63% male; age 20.7±6.0 years; range 14-35 years; BSA 2.01±0.34m
2
) participating in 31 sporting disciplines, underwent echocardiography as part of a pre-participation screening evaluation. Aortic root dimensions, measured at the sinus of Valsalva level, were analysed according to ESC guidelines.

Results
were compared to 415 healthy controls (57% male; age 22.1±6.4 years; range 14-35 years) of similar size (BSA 1.98±0.36m
2
) and 50 patients with Marfan syndrome (54% male; age range 18-68 years). Individuals with a bicuspid valve had been excluded. Results: Athletes and controls exhibited similar mean aortic root dimensions (27.9±4.1mm, range: 16-43mm, vs. 27.9±4.3mm, range: 17-38mm; p=1.000). Marfan patients had greater mean aortic root dimensions compared with athletes (39.1±5.1mm; range 26-48 mm vs. 27.9±4.1mm). The aortic root was ≥40 mm in 6 male athletes (0.8%) and 1 female athlete (0.2%), compared with none in the controls. In contrast, 22 males (81%) and 6 females (26%) with Marfan syndrome showed an aortic root ≥40mm (p<0.0001).

Conclusion:
Unlike other cardiac dimensions, athletes generally exhibit similar mean aortic root dimensions to controls. In absolute terms, few British athletes reveal an aortic root dimension ≥40mm. This cross sectional study provides support for the guidelines set by the expert Bethesda consensus panel.
Abstract 19366: NG2 Ablation Aggravates Obesity and Hyperlipidemia but Reduces Atherogenesis
Authors: She Zhi-Gang , Chang Yunchao , Smith Jeffrey W , Ruoslahti Erkki , Stallcup William B
Published: April 2024

Background & Hypothesis: Ablation of chondroitin sulfate proteoglycan 4 (NG2) impairs brown fat development and function, leading to increased levels of serum lipids, increased lipid storage, and increased white fat mass. Since obesity and hyperlipidemia are two key risk factors for atherosclerosis, we wondered how NG2 ablation would affect atherogenesis. In addition to its expression by white and brown adipocytes, NG2 is also highly expressed by mesenchymal stromal cells (MSCs) in both human and mouse atherosclerotic plaques. NG2 could therefore could affect atherogenesis in the context of MSC function, as well as in the context of adipocyte function. Methods & Results: We compared atherosclerotic plaque formation between ApoE null/NG2 wild type and ApoE null/NG2 null mice fed with a Western diet. Body weight, serum cholesterol, and triglyceride levels are similar in the two lines of mice in the early (10 weeks) and middle (16 weeks) stages of atherogenesis. However, all three parameters are significantly increased in the double null mice after 26 weeks of high fat diet induction. Aortic plaque areas are also similar in the two mouse lines at 10 and 16 weeks, but are reduced by 30% in double null male mice after 26 weeks of induction. Lipid content, collagen content, and the abundance of macrophages, smooth muscle cells, and MSCs are all reduced in plaques by 20-30% in double null males at 26 weeks. Like other chondroitin sulfate proteoglycans, purified NG2 exhibits strong LDL binding in ELISA tests. At the cellular level, cultured NG2 null MSCs bind less LDL than wild type MSCs. In vivo, LDL retention in NG2/ApoE double knock-out plaques is about 30% less than that seen in ApoE null/NG2 wild type plaques. Summary & Significance: In spite of the obese and hyperlipidemic phenotype of ApoE null/NG2 null mice during later stages of atherogenesis, the absence of NG2 nevertheless results in less retention of LDL in the mouse aorta, thus restricting plaque expansion. Inhibition of NG2 may be a promising therapeutic strategy for atherosclerosis and related diseases.