bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 18584: Filamin-A Mutations Causing Mitral Valve Prolapse Alters Integrin Expression and Causes Breakdown of Mechanotransduction
Authors: Padala Muralidhar , Zamani Marzieh H , Sarathchandra Padmini , Merot Jean , Gorelik Julia , Yacoub Magdi H , Chester Adrian H
Published: July 2021

Introduction:
Mutations in the gene encoding Filamin-A, a cytoskeletal protein, were identified in patients with familial mitral valve prolapse(MVP). Mitral valves in these patients were floppy and appeared myxomatous, but the underlying mechanisms governing such changes are unclear. In this study, we sought to investigate the impact of these mutations on cultured cells in comparison with wild type Filamin-A, to delineate the mechanisms underlying MVP.

Methods:
Four immortal cell lines were established - Filamin-A KO, Filamin-A WT, G288R mutated Filamin-A, and P637Q mutated Filamin-A. Cells were cultured on plastic petri-dishes for a week, and at confluence the cells were imaged under a microscope, then their 3D morphology and mechanical stiffness measured with scanning ion conductance microscopy, and then the cells were assayed for integrins and counted using flow cytometry.

Results:
Filamin-A KO cells developed blebs on the surface, were flat and did not sufficiently attach to the cell culture substrate, while WT cells demonstrated excellent attachment and formed extensive lamellapodi and filipodia (Fig 1A). Both G288R and P637Q mutated cells had reduced extensions, with a cell structure that is small in circumference but large in height(Fig 1B). α1, α2, α3, α5, β1, β3, β4, α5β3, α2β1 integrin expression was drastically reduced in both G288R and P637Q mutations, compared to WT (Fig 1C1-C2). A 24 hour substrate attachment assay demonstrated 30% attachment of G288R cells were attached and viable, 50% of the P637Q cells were attached and viable, and 98% of WT cells were attached and viable, with similar results seen in gel contraction studies (Fig 1D).

Conclusions:
Filamin-A mutations associated with mitral valve prolapse seem to alter fundamental cellular mechanisms essential for cell attachment to matrix, motility and mechanotransduction.
Abstract 18587: Downregulation of Pulmonary Artery Endothelial Catechol-o-methyltransferase Activity by Aldosterone Increases Norepinephrine Levels in Pulmonary Arterial Hypertension
Authors: Torquato Samantha , Ishikawa Kiyotake , Aguerro Jaume , Maron Bradley A , Loscalzo Joseph , Hajjar Roger J , Leopold Jane A
Published: July 2021

Elevated levels of norepinephrine (NE) occur in pulmonary arterial hypertension (PAH) and are determined, in part, by the activity of catechol-
O
-methyltransferase (COMT). COMT degrades catecholamines, is negatively regulated by calcium, and is expressed by pulmonary artery endothelial cells (PAEC). As hyperaldosteronism occurs in PAH and aldosterone (ALDO) influences calcium levels, we hypothesized that ALDO decreases COMT activity to increase NE levels in PAH. Accordingly, human PAEC were treated with ALDO (10
-7
mol/L), a level that is achieved clinically in PAH, for up to 72 h. Compared to vehicle-treated PAEC, ALDO decreased COMT activity by 59.2 ± 6.2% (p<0.01) to increase NE levels in the medium (122.4 ± 11.8 vs. 210.7 ± 15.5 pg/mL/mg protein, p<0.01). This occurred as a result of an ALDO-mediated decrease in COMT protein expression by 52.6 ± 9.3% (p<0.01) as well as an increase in intracellular calcium levels (102.9 ± 21.0 vs. 167.7 ± 17.8 nmol/L, p<0.05) to inhibit activity. These effects were abrogated by coincubation with spironolactone. To determine the in vivo relevance of these findings, COMT was examined in the rat monocrotaline model of PAH with confirmed hyperALDO. COMT was decreased (47.6 ± 10.2 %control, p<0.05) in remodeled pulmonary arterioles with a concomitant increase in lung NE levels (432.8 ± 44.5 vs. 899.7 ± 34.2 pg/mL, p<0.01) compared to control rats. In the porcine pulmonary vein banding model of pulmonary hypertension (PH-pigs) with elevated mean pulmonary artery pressure (15[13-15] vs. 35[27-43], p<0.01) and pulmonary vascular resistance (PVR) index (1.97[1.74-2.28] vs. 5.78[2.61-8.75], p <0.05), ALDO levels were also increased (27.1 ± 5.1 vs. 60.8 ± 10.6 pg/mL, p<0.03) in advance of right heart failure as compared to sham controls. PH-pigs demonstrated a 48.3 ± 9.9% (p<0.02) decrease in pulmonary vascular COMT expression and an increase in NE levels (114.6 ± 20.2 vs. 1,622.6 ± 489.2 pg/mL, p<0.02) that correlated positively with ALDO levels (R
2
=0.58, p<0.02). These findings were confirmed in patients with PAH. Together, these data indicate that there is crosstalk in the pulmonary vasculature between ALDO and the sympathetic nervous system to regulate NE levels in PAH, and thus, have implications for therapeutic interventions.
Abstract 18611: Increased Absorption and Decreased Synthesis of Cholesterol in Cardiac Sarcoidosis
Authors: Simonen Piia , Lehtonen Jukka , Gylling Helena , Kupari Markku
Published: July 2021

Introduction:
Sarcoidosis is a multisystem inflammatory disease characterised by the formation of granulomas in many tissues. Some reports suggest that the disease is associated with altered lipoprotein cholesterol profiles, but there is no deeper knowledge of cholesterol metabolism in these patients.

Hypothesis:
We tested the hypothesis that cholesterol metabolism is abnormal in cardiac sarcoidosis (CS).

Methods:
The study population consisted of 39 patients with histologically verified CS (31 women and 8 men, mean age 53 years) and 124 healthy controls of similar age and gender. 31 of the CS patients were on immunosuppressive treatment. Serum lipids were determined and cholesterol metabolism was evaluated by measuring serum markers of cholesterol absorption (cholestanol, campesterol and sitosterol) and synthesis (desmosterol and lathosterol) as ratios to cholesterol with gas-liquid chromatography.

Results:
CS was inactive in all patients based on clinical evaluation, cardiac ultrasound, and stable levels of serum TnT and proBNP. Serum total, LDL and HDL cholesterol concentrations (mean±SE) were 5.6±0.2, 3.3±0.1 and 1.5±0.1 mmol/l, respectively, and serum triglyceride averaged 1.7±0.7 mmol/l. These values did not differ from those of controls. Cholesterol absorption markers were higher in CS patients than in controls (eg. serum campesterol level 245±17 vs 190±17 10
2
μmol/mmol of cholesterol, p<0.05). Cholesterol synthesis markers were lower in CS patients than in controls (eg. serum lathosterol level102±8 vs 195±17 10
2
μmol/mmol of cholesterol, p<0.001). Concentrations of serum lipids and non-cholesterol sterols did not associate with the use of immunosuppressive drugs. Markers of cholesterol absorption and synthesis did not correlate with serum TnT levels, but there was a significant positive correlation between proBNP and cholesterol absorption markers (r=0.351, p<0.05).

Conclusions:
We conclude that, in CS, cholesterol absorption is increased and its synthesis is decreased. The underlying mechanisms remain obscure and deserve further study. This is the first time that abnormal cholesterol metabolism has been described in CS.
Abstract 18623: Evaluation of Left Ventricular Geometry Changes in Patients with Tight Aortic Stenosis Using Multi-detector Computed Tomography
Authors: Jang Jeong Yoon , Yang Dong Hyun , Cheon Sang Soo , Park Hee-Soon , Kim Min Su , Choi Hyo In , Choi Hanul , Roh Jae-hyung , Sun Byung Joo , Kang Joon-Won , Kim Dae-Hee , Song Jong-Min , Kang Duk-Hyun , Song Jae-Kwan
Published: July 2021

Background:
Although aortic stenosis (AS) is a prototype of left ventricular hypertrophy (LVH) due to pressure overloading, patterns of LV geometric changes in patients with tight AS and their potential impact remain to be established.

Methods:
LV mass index (LVMI), LV end-diastolic volume (LVEDV) and regional LV wall thickness in 16 segments were measured in 147 patients with tight AS (indexed aortic valve area [AVA] < 0.6 cm
2
/m
2
) using multi-detector computed tomography and compared with those of 32 normal controls. LVH was defined as LVMI >95
th
percentile of normal controls and LV remodeling as increased LVM/LVEDV with normal range of LVMI. Asymmetric remodeling or hypertrophy were used for patients with septal wall thickness >1.5 fold compared to the opposite segment. Patients with increased LVMI but normal range of LVM/LVEDV were classified to have eccentric LVH and those with eccentric LVH and decreased LV systolic function were defined to have de-compensation.

Results:
AS patients with mean indexed AVA of 0.36 ± 0.08 cm
2
/m
2
showed 7 different patterns of LV geometry including normal LV geometry (n=44), remodeling (n=7), asymmetric remodeling (n=7), concentric hypertrophy (n=16), asymmetric hypertrophy (n=23), eccentric hypertrophy (n=38), and de-compensation (n=12). Peak transaortic velocity (r=0.31, p<0.001) and E/E’ (r=0.29, p<0.001) showed positive correlation with LVMI: compared to other groups, patients with LVH (concentric or asymmetric or eccentric) showed higher peak velocity and E/E’ with smaller AVA (all, p<0.001). Despite similar AVA and mean pressure gradient, patients with E/E’ ≥ 15 (n=110) showed different LV remodeling patterns (p=0.028) with higher LVMI (97.8 ± 21.1 vs 86.4 ± 20.2 g/m
2
, p=0.005).

Conclusions:
Various remodeling patterns of LV geometry were observed in tight AS and individual variation in LVH severity under similar LV pressure overloading could explain different severity of diastolic dysfunction.
Abstract 18646: Safety Aspects of High Intensity Interval Training versus Moderate Intensity Continuous Exercise Training in Patients Post Acute Coronary Syndrome
Authors: Hayami Douglas , Gayda Mathieu , Juneau Martin , Thorin Eric , Larouche Jean-François , Lapierre Gabriel , Tardif Jean-Claude , Nigam Anil
Published: July 2021

Introduction:
Exercise training in patients who have suffered an acute coronary syndrome is associated with a significant reduction in mortality and cardiovascular events. Moderate intensity continuous exercise training (MICET) is currently recommended. Recently, high-intensity interval training (HIIT), that utilizes short bursts of very intense efforts interspersed with periods of recovery, has been explored as an alternative to MICET. The safety aspects of HIIT in patients post acute coronary syndrome (ACS) have been poorly described.

Methods:
Thirty-seven low-risk patients post ACS (65% STEMI, fully revascularized, EF > 40%, age 61±9 years, 8 women) were randomized 4 weeks to 6 months post ACS; to 12 to 18 weeks of 2-3 sessions/week (total: 36 sessions) of isocaloric MICET or HIIT on cycle ergometer. VO2peak and maximal aerobic power (MAP) were determined using maximal cardiopulmonary exercise test (CPET) on cycle ergometer and continuous ECG and BP were monitored every 2 min. Cardiometabolic profile (body composition, blood lipids, BP), arrhythmias (24h-holter monitoring) and left ventricular ejection fraction (LVEF) were measured before and after the intervention. MICET consisted of: 5 min of warm-up period, 37 min at 60% maximal aerobic power (MAP) and 5 min of cool down. HIIT included: 5 min of warm-up, 3 sets of 10 minutes of repeated phases of 15 sec at 100% MAP alternating with 15 sec passive recovery and 5 min of cool down.

Results:
Significant improvement in VO2peak (normalized by lean body mass (LBM)) was observed in the MICET group only (MICET VO2peak: 29.26±4.87 vs. 34.26 mL/min/LBM, p<0.05), but not in the HIIT group (HIIT VO2peak: 30.01±6.36 vs. 30.81±4.88 mL/min/LBM, p>0.05). No significant improvements in body composition, BP or blood parameters were observed in either group. No adverse events including no increase of ventricular arrhythmias or deterioration of LVEF were noted with HIIT (56±6 vs. 57±7%, p>0.05).

Conclusion:
In patients post-ACS, MICET appeared to have a greater impact on VO2peak compared to HIIT, while no improvement in cardiometabolic risk profile was observed in either group. HIIT was well tolerated and was not associated with increased ventricular arrhythmias or deterioration of cardiac function.
Abstract 18686: Association of Obesity Susceptibility Gene Variants With Cardiometabolic Phenotypes in Morbid Obesity
Authors: Fenk Sabine , Koehler Marissa , Strack Christina , Hubauer Ute , Zeller Judith , Manka Margareta , Meindl Christine , Zimmermann Martina , Fischer Marcus , Baessler Andrea
Published: July 2021

Introduction:
Genome-wide association studies (GWAs) have identified several gene variants strongly associated with increased body mass index (BMI) and obesity. However, their association with the cardiometabolic consequences of obesity is unclear. We performed a study of 40 validated variants recently identified in two large metaanalysis GWAS and analyzed their association with related cardiovascular and metabolic traits of severe obesity.

Methods:
Genotyping was performed in 320 deeply-phenotyped obese subjects (mean BMI 41±9 kg/m2, aged 44±12 years), participating in a standardized weight reduction program. Anthropometric parameters, parameters of glucose/insulin metabolism, oxidative stress and early atherogenesis, adipokines, adhesion molecules, apolipoproteins, cardiac function and structure, intima media thickness and arterial elasticity were assessed standardized after 12h fast.

Results:
The transmembran protein TMEM18 rs939583 variant was significantly related to several parameters of adiposity (i.e. BMI β-estimate 1/2 risk alleles vs. no risk allele: 3.7±2.2/ 5.5±1.9, p=0.0009), epicardial fat thickness (p=0.023), insulin (p=0.002), fasting glucose (p=0.007), HOMA-IR (p=0.0008), and leptin (p=0.008) levels, systolic (p=0.007) and diastolic (p=0.009) blood pressure, arterial hypertension (frequency in subjects with 0/1/2 risk allele(s): 14/30/46%, p=0.001), and the metabolic syndrome (29/29/48%, p=0.029). Moreover, the BDNF rs10767664 variant was significantly associated with ApoA1, ApoA2, HDL cholesterol and soluble CD40L levels.

Conclusion:
TMEM18 and BDNF variants increased the risk of metabolic syndrome components, probably through their effect of abdominal obesity. However, several gene variants that have been found to be associated with BMI with small effects in large scale GWAS, did not seriously alter obesity related cardiometabolic traits.
Abstract 18687: PARP9 and PARP14 are Novel Regulators of Macrophage Activation
Authors: Iwata Hiroshi , Yoshida Hideo , Ricchiuto Piero , Hara Takuya , Yamada Iwao , Mojcher Alexander , Libby Peter , Boothby Mark , Aikawa Elena , Singh Sasha , Aikawa Masanori
Published: July 2021

Background:
Pro-inflammatory “M1” macrophages may promote atherogenesis, while “M2” macrophages may favor an anti-inflammatory milieu. Our global proteomics of M1 and M2 cells identified ADP-ribosylation enzymes PARP9 and PARP14 as novel regulators of macrophage activation. The present study has examined the underlying mechanisms and explored in vivo evidence for their role in vascular disease.

Methods and Results:
IFN gamma (M1) stimulation induced and IL-4 (M2) decreased PARP9 and PARP14 in mouse and human macrophages. siRNA silencing of PARP14 enhanced expression of M1 genes (e.g. TNFα, iNOS) and activation (phosphorylation) of pro-inflammatory STAT1 while suppressing M2 markers (e.g., Arginase 1) and anti-inflammatory STAT6. Conversely, PARP9 silencing suppressed M1 polarization and STAT1 activation. These results suggest that PARP14 inhibits and PARP9 promotes a pro-inflammatory macrophage phenotype. Co-immunoprecipitation indicated that PARP14 and PARP9 physically interact. ADP-ribosylation assays revealed that PARP9 impairs PARP14-induced ribosylation (Figure A). Targeted proteomics via high-resolution mass spectrometry demonstrated that PARP14 ADP-ribosylates at least two sites in STAT1α, which PARP9 suppressed. Mechanically injured arteries of Parp14-/- mice had accelerated lesion formation and macrophage accumulation. Peritoneal and plaque macrophages of PARP14-/- mice showed increased STAT1 phosphorylation, decreased STAT6 phosphorylation, enhanced M1 gene expression, and reduced M2 responses (Figure B, laser capture microdissection). More macrophages[[Unable to Display Character: ]]were immunoreactive for PARP9 in human “unstable” plaques than in “stable” plaques (64.6±16.2% vs. 30.8±12.3%, p<0.01, n=5).

Conclusions:
PARP14 and PARP9 reciprocally regulate the mechanisms of macrophage activation, offering the potential for new therapies for cardiovascular diseases and other conditions, in which macrophage activity impacts outcomes.
Abstract 18698: Identification of a Novel Cardiac Progenitor Population Expressing Pw1/peg3 in the Murine Heart
Authors: Yaniz-Galende Elisa , Formicola Luigi , Mougenot Nathalie , Legrand Lise , Chen Jiqiu , Hajjar Roger J , Marazzi Giovanna , Sassoon David , Hulot Jean-Sebastien
Published: July 2021

The myocardium responds to injury by recruiting cardiac progenitor cells (CPCs) to the injured tissue to promote cardiac repair. Although different classes of CPCs have been identified, their contribution in physiological and pathological conditions remains unclear. PW1 gene has recently been proposed as a marker of resident adult stem and progenitor cell populations in several adult tissues. Our goal was to characterize and determine the role of PW1+ population in the heart. Here, we employ immunostaining and fluorescence-activated cell sorting (FACS) analysis in PW1-reporter mouse to perform qualitative and quantitative analyses of PW1+ population in the heart. We first found that PW1+ cells are mainly located in the epicardium and myocardial interstitium of normal hearts. The average percentage of PW1+ cells, as assessed by FACS, was 1.56±1.41%. A subset of PW1+ cells also co-express other CPC markers such as Sca-1 (52±22%) or PDGFR1α (43±14%). In contrast, a very small proportion of PW1+ cells co-express c-kit (6±5%). To investigate the contribution of PW1+ cells in pathological conditions, we then performed myocardial infarction (MI) by LAD ligation in PW1-reporter mice. We found that MI resulted in a 3-fold increase in the number of PW1+ cells in infarcted mice compared with sham-operated groups, at 1 week post-MI (1.16%±0.47% in sham versus 3.43%±0.82 in MI). This population preferentially localized in the injured myocardium and border area. PW1+ cells were isolated by FACS from the whole infarcted heart from PW1-reporter mice. In vitro differentiation assays reveal that purified PW1+ cells are multipotent and can spontaneously differentiate into smooth muscle cells, endothelial cells and cardiomyocyte-like cells. Taken together, our data identify a novel PW1+ cardiac progenitor population with the potential to undergo differentiation into multiple cardiac lineages, suggesting their involvement in cardiac repair in normal and pathological conditions.

The discovery of a novel population of cardiac progenitor cells, augmented following MI and with cardiogenic potential, provides a novel target for therapeutic approaches aimed at improving cardiac regeneration.
Abstract 18705: The miR-130/301 Family Exerts Systems-level Regulation of Proliferation, Vasoconstriction, and Extracellular Matrix Deposition to Control Pulmonary Hypertension
Authors: Bertero Thomas , Cottrill Katherine A , Lu Yu , Annis Sofia , Hale Andrew , Krauszman Adrienn , Bhat Balkrishen , Saggar Rajan , Saggar Rajeev , Wallace W. D , Ross David J , Vargas Sara O , Graham Brian B , Kumar Rahul , Black Stephen M , Fratz Sohrab , Fineman Jeffrey R , West James D , Haley Kathleen J , Waxman Aaron B , Kuebler Wolfgang M , Chau B. N , Chan Stephen Y
Published: July 2021

Background:
Pulmonary hypertension (PH) is a deadly vascular disease with enigmatic molecular origins. Facets of PH have been characterized in isolation, but many have yet to be unified by a common upstream regulator.

Methods & Results:
We constructed a network
in silico
of 247 genes and 2,274 functional interactions involved in PH. Using this model and advanced network analysis, we predicted the miR-130/301 family to have the most diverse pool of PH-relevant target genes among conserved microRNAs (miRNAs). Guided by these predictions, we found that this family was up-regulated by hypoxia, inflammatory cytokines, and factors genetically linked to PH. MiR-130/301 family members were also up-regulated in remodeled pulmonary vessels in 7 animal models and 3 human subtypes of PH. Via gain- and loss-of-function experiments
in vitro
, we found that miR-130/301 suppressed a cohort of PPARgamma-related targets to regulate two pro-proliferative pathways (the apelin-miR-424/503-FGF2 axis in PAECs and the STAT3-miR-204-SRC axis in PASMCs); vasomotor tone (
e.g.
, endothelin-1 and endothelial nitric oxide synthase); and extracellular matrix remodeling (
e.g.
, the collagen crosslinking enzyme LOX). In turn, delivery of miR-130a mimic oligonucleotides in pulmonary vessels of mice altered expression of the predicted cohort of PPARgamma-related factors, leading to increased vascular remodeling (19.62±1.36 percent muscularized arterioles for miR-130a vs. 6.98±0.55 percent for scrambled control, p<0.05, mean±SEM), pulmonary vascular resistance (791±124.5 [10
3
*dyn*s*cm
-5
] for miR-130a vs. 462±25.4 for control, p<0.05), and perivascular collagen deposition and cross-linking (9.67±1.24 percent of perivascular area positive for Picrosirius Red stain vs 1.24±0.15 percent for scrambled control, p<0.05). After PH initiation in mice (chronic hypoxia+SU5416), coordinated inhibition of these miRNAs
in vivo
via antisense oligonucleotides mitigated these effects.

Conclusions:
We used network modeling to identify miR-130/301 as a master regulator of PH and a novel potential therapeutic target. These findings provide critical support for the evolving application of network modeling to discover the hidden molecular origins of PH and other human diseases.
Abstract 18706: Multi-Sequence Non-Contrast MRI Characterisation of Experimental Venous Thrombi Predicts Susceptibility to Lysis and is Feasible in Man
Authors: Saha Prakash , Phinikaridou Alkystis , Andia Marcelo E , Patel Ashish S , Grover Steven P , Bajwa Adnan , Modarai Bijan , Botnar Rene , Smith Alberto
Published: July 2021

Introduction:
We have previously demonstrated that non-contrast MRI using magnetisation transfer rate (MTR), apparent diffusion coefficient (ADC) and T1 mapping can characterise different aspects of organisation in a resolving venous thrombus. We now investigate whether the combination of these non-contrast agent MRI sequences can be used to identify thrombi suitable for lysis in an experimental model, and whether multi-sequence thrombus imaging (MSTI) can be translated to man.

Methods:
Magnetisation transfer, diffusion weighted images and T1 relaxation times were measured at days 2, 4, 7, 10, 14, 21 and 28 after venous thrombus induction in 8-10wk old male BALB/C mice (n=8/gp). Tissue plasminogen activator (10mg/kg) was administered through tail vein injection immediately after imaging at each time point and mice scanned 24hrs later to evaluate the effect of lysis. This was considered successful if more than 50% of the vein recanalised.

Murine imaging sequences were combined and optimised to image the pelvic veins in man using healthy volunteers in order to produce a clinically useable imaging card. MSTI sequences were validated using phantoms before application to patients with iliofemoral deep vein thrombosis (DVT) undergoing lysis.

Results:
ROC curve analysis shows that the combination of MTR smaller than 2,900(%/cm3), ADC larger than 0.93(x10-3 mm2/s) and T1 shorter than 784ms has a sensitivity of 88% and specificity of 97% to identify experimental thrombi amenable to lysis. MSTI is feasible in man, with optimisation leading to successful characterisation of iliofemoral DVT in under 25mins (Figure 1).

Conclusions:
Non-contrast MR imaging, using a combination of MTR, ADC and T1 mapping, accurately identifies experimental venous thrombi susceptible to lysis. These MSTI sequences can also be readily translated to man where may find utility in characterising the age and structure of thrombus, and to stratify patients undergoing thrombolysis.
Abstract 18729: Comparative Analysis of the Use of Extracorporeal Membrane Oxygenation During Cardiopulmonary Resuscitation Within a Pediatric Cardiac Intensive Care Unit
Authors: Conrad Stephanie J , Bacon Matthew K , Hatch Brittney C , Hughes John David , Terrell Michelle K , Maynord Patrick , Smith Andrew H
Published: July 2021

Background:
Mechanical support to aid in restoration of circulation during cardiopulmonary resuscitation (CPR) is increasingly common in the pediatric cardiac intensive care unit (CICU). We sought to both identify and quantify factors predicting the implementation of extracorporeal membrane oxygenation to support CPR (eCPR).

Methods and Results:
Events associated with CPR from July 2010 through December 2013 within our pediatric CICU were retrospectively reviewed. Of 135 arrests among 88 patients, 84% were among postsurgical patients and 98% (n=133) resulted in a return of circulation, either spontaneous (n=100, 74%) or with the assistance of mechanical support (n=33, 24%). Median age at arrest was 106 days (interquartile range [IQR] 26-207 days) and weight was 3.9 kg (IQR 3.0-6.0 kg). Median length of stay (LOS) at the time of arrest was 5 days (IQR 1-49 days). Common primary causes included low cardiac output (38%), respiratory failure (33%), and arrhythmia (15%). Univariate predictors of an eCPR arrest included smaller size (3.3 v. 4.3 kg, p=0.004), younger age (25 v. 130 days, p<0.001), shorter length of stay at time of arrest (1 v. 8.5 days, p=0.001), single ventricle physiology (30% v. 14% among biventricular physiology arrests, p=0.04), and arrests not related to respiratory failure (34% v. 5% eCPR among respiratory failure arrests, p<0.001). Unit factors not associated with an increased frequency of arrests resulting in eCPR included unit capacity, night shift, and the experience levels of both the bedside nurse and attending. Among patients with at least one arrest, median ICU LOS was 18 days (IQR 9-72 days) and overall survival to ICU discharge was 72%. Survival to ICU discharge was not significantly different with respect to use of eCPR as compared to conventional CPR (60% v. 77% respectively, p=0.11).

Conclusions:
We report predictors of the need for mechanical support during cardiopulmonary resuscitation within a pediatric CICU, and demonstrate comparable post-resuscitation survival to ICU discharge among those rescued with eCPR. Further longitudinal investigation is necessary to identify potential eCPR-associated differences in morbidity and neurocognitive outcomes following a CICU arrest.
Abstract 18739: Acute Effect of the Na+/ca2+ Exchanger (ncx) Inhibitor Sea0400 on Diastolic Function in vivo and in vitro in a Model of Heart Failure With Preserved Ejection Fraction
Authors: Primessnig Uwe , Pieske Burkert , Heinzel Frank
Published: July 2021

Background:
Heart failure with preserved ejection fraction (HFPEF) is increasingly common but underlying cellular mechanisms are not well understood. We investigated cardiomyocyte function and the role of SEA0400, in vivo and in vitro in a rat model of diastolic heart failure.

Methods:
Young male Wistar rats were subjected to subtotal nephrectomy (NXT) or sham operation (SOP). After 24 weeks in vivo (pressure-volume loops) and in vitro characterization (cardiomyocyte function (Ca2+ transients, sarcoplasmic reticulum (SR) diastolic Ca2+ leak (Ca2+ sparks) and SR Ca2+ content)) as well as NCX function (caffeine-induced Ca2+ transient, TAU) and protein expression) were determined without an with the NCX inhibitor SEA0400 (in vivo: 1 mg/kgKG for 30 minutes/ in vitro: 300nM for 5 minutes incubation).

Results:
NXT rats showed stable compensated renal impairment and signs and symptoms of HFPEF (hypertrophied left ventricle (LV), left- and upward shift of end diastolic pressure (EDP) volume relationship, increased lung weight/body weight ratio indicating pulmonary congestion and preserved LV systolic function (EF, dP/dt)). In LV cardiomyocytes from NXT Ca2+ transient amplitude was unchanged but time for early (50%) decay was significantly prolonged at 24 weeks and correlated with diastolic dysfunction (EDP) in vivo. TAU of the caffeine transient was significantly prolonged at 24 weeks indicating reduced NCX forward mode activity, while NCX protein expression was up-regulated, suggesting increased NCX reverse mode activity. Ca2+ spark frequency was increased and SR Ca2+ content was decreased in NXT (p<0.05). SEA0400 significantly accelerated Ca2+ transient decay and reduced Ca2+ spark frequency in NXT. Acute in vivo treatment with SEA0400 significantly enhanced active relaxation (isovolumetric relaxation constant) of the LV in NXT.

Conclusion:
This model of HFPEF is associated with prolonged cytosolic Ca2+ decay and increased diastolic Ca2+ leak in LV cardiomyocytes. Acute treatment with NCX inhibitor SEA0400 normalized cytosolic Ca2+ transients, improved net transsarcolemmal Ca2+ export and decreased SR Ca2+ leak in NXT, in line with a role for reverse mode NCX activity in HFPEF. In vivo active relaxation was improved after acute SEA0400 treatment.
Abstract 18766: Trastuzumab Cardiomyopathy is Prevented by the Administration of Ranolazine at the End of Antineoplastic Treatment in Model Mouse
Authors: Coppola Carmela , Piscopo Giovanna , Galletta Francesca , Maurea Carlo , Rea Domenica , Arra Claudio , Maurea Nicola
Published: July 2021

Introduction:
Trastuzumab (TRAS), an anti-ErbB2 inhibitor, is the foundation of care for patients with HER2-positive breast cancer. Cardiovascular complications due to TRAS are a growing problem in clinical practice that may frustrate modern oncological outcome of therapy (asymptomatic left ventricular dysfunction and heart failure). The mechanisms of cardiotoxicity of TRAS have not been fully elucidated and can include changes in Ca2+ regulation related to blockade of ErbB2 and PI3K-Akt and MAPK pathways.

Hypothesis:
Here, we aim at assessing whether Ranolazine (RAN), administered after TRAS treatment, blunts TRAS cardiotoxicity in vivo.

Methods:
To evaluate cardiac function in vivo, fractional shortening (FS) and ejection fraction (EF) were measured by M/B mode echocardiography and radial and longitudinal strain (RS and LS) were measured using 2D speckle-tracking echocardiography, in C57/BL6 mice, 2-4 mo old, at day 0, and after 2 and 7 days of daily administration of TRAS (2.25 mg/kg/day, ip). These measurements were repeated after 5 days of RAN treatment (305 mg/Kg/day, gavage, dose comparable with that used in humans of 750 mg twice) initiated at the end of TRAS treatment.

Results:
In our in vivo studies, after 7 days with TRAS, FS decreased to 48.7±4.1%, p<0.01 vs 62.3±0.8% (sham), EF to 81.8±3.5%, p<0.01 vs 91.7±0.5% (sham), RS to 21±8.1%, p<0.01 vs 43.2±4% (sham), and LS to -11±3.7%, p<0.01 vs -38.8±6% (sham). In mice treated with RAN for 5 days after TRAS treatment, the indices of cardiac function recovered: FS was 61±1.2%, EF was 91±0.7%, p<0.01; RS was 21±8.1%, p<0.05 vs TRAS+RAN. However the alteration of LS persists after treatment with RAN (-15.4±5.1%, p=0.3 vs TRAS+RAN).

Conclusions:
RAN post-treatment blunts cardiotoxic effects due to TRAS, as demonstrated by the normalization of the values of FS, EF and RS. The explanation for the persistent abnormalities of LS could be that the subendocardial fibers, responsible for the alteration of LS, are the first to impair and may be the last to recover.
Abstract 188: Temporal Changes in Morphological Characteristics of Ventricular Fibrillation from Out-of-Hospital Cardiac Arrest in an Asian Community
Authors: Chen Weiting , Chen Nai-Chuan , Chen Yen-Pin , Lee Yi-Chia , Wang Hui-Chih , Lin Chen , Yang Hui-Wen , Tseng Yu-Hsin , Chang Yi-Chung , Yang Chih-Wei , Ko Patrick Chow-In , Chiang Wen-Chu , Lin Liang-Yu , Lo Men-Tzung , Ma Matthew Huei-Ming
Published: July 2021

Introduction:
Ventricular fibrillation (VF) is the most common arrhythmia causing out-of-hospital cardiac arrest (OOHCA) and defibrillation remains the mainstay of its treatment. Successful defibrillation is linked to VF morphology characteristics, and is affected by VF duration, quality of cardiopulmonary resuscitation (CPR) and emergency medical service (EMS) responsiveness. This study aimed at comparing VF morphology characteristics and their relationships with patients and EMS characteristics, as well as outcomes, in an Asian community.

Method:
Electrocardiographic recordings of VF signals from automated external defibrillators (AEDs) in 2008 to 2012 were obtained from OOHCA subjects in Taipei city, a metropolitan with 2.65 million residents in 272km2. Amplitude spectrum analysis (AMSA) and DFAα2 were calculated and compared year by year in the study period.

Results:
A total of 612 OOHCA subjects with VF were included for analysis. Both DFA and AMSA changed significantly over time (χ
2
for trend: -0.128 for DFA, p<0.01; 0.092 for AMSA, p=0.02). There was no change in gender, age, and bystander CPR rates; however, in later years there were more witnessed arrests, shortened EMS responses, and better sustained (>2 hr) return of spontaneous circulation (ROSC) and neurological outcomes (CPC 1&2). The time trend for DFAα2 (OR 0.98, CI 0.96-0.99, p=0.003), but not for AMSA (OR 1.07, CI 0.99-1.14), remained after adjustment for confounders. Both DFAα2 and AMSA were associated with sustained ROSC (DFA OR 0.08, CI 0.04-0.18, p<0.001; AMSA OR 1.18, CI 1.01-1.38, p=0.03) and CPC 1&2 (DFA OR 0.04, CI 0.01-0.16, p<0.001; AMSA OR 1.30, CI 1.07-1.57, p=0.008) in multiple regression models.

Conclusions:
DFAα2 and AMSA, two important VF characteristics, changed significantly over time in an Asian community, and were associated with improved outcomes. This might reflect improvement in community chain of survival especially among EMS responses and community quality of CPR.
Abstract 18802: Sex Differences in the Risk of 1-year Re-hospitalization in Young Women and Men following Acute Myocardial Infarction
Authors: Dreyer Rachel P , Nkonde-Price Chileshe , Kennedy Kevin , Vaccarino Viola , Parashar Susmita , Dharmarajan Kumar , Hammond Gmerice , Lichtman Judith H , Smolderen Kim G , Buchanan Donna M , Spertus John A , Krumholz Harlan M
Published: July 2021

Background:
It is currently unknown whether young women (≤55 yrs) have a greater risk of all cause-re-hospitalization following AMI than similarly aged men. This is an important subgroup to study considering younger women’s higher post-AMI mortality compared with age-matched men. We determined if there are sex differences in the 1-year re-hospitalization rate, including factors associated with this outcome.

Methods:
Young AMI patients (N=1414, 28% women) were identified from the 24-center prospective, observational TRIUMPH study. Patient data was abstracted from medical records and health status was collected through interviews at the time of the AMI [Short Form 12 (SF-12), and the Seattle Angina Questionnaire (SAQ)]. Physicians adjudicated each re-hospitalization the year after discharge. We compared sexes using t-test/x2 and Cox proportional hazards analysis, sequentially adjusting for important covariates.

Results:
The crude 1-yr re-hospitalization rate was higher in women vs. men (32% vs. 23%, P<0.001), and women also had more hypertension (64% vs. 53%), diabetes (34% vs. 22%), lung disease (9% vs. 3%), and depression (14% vs. 6%; P<0.0001 for all). At presentation, women had worse general health scores (SF-12 physical summary=41±12 vs. 44±11, mental summary= 45±13vs.49±11, P<0.0001 for all), more angina (SAQ angina frequency=83±22 vs. 87±19), poorer physical function (SAQ physical limitation=82±24 vs. 89±19) and worse quality of life (57±23 vs. 62±23; P<0.001 for all). In the fully adjusted model, female sex was no longer significantly associated with 1-year re-hospitalization post AMI (HR=1.20, 95%CI = 0.93, 1.56).

Conclusion:
Young women have a higher crude rate of 1-year re-hospitalization post AMI compared with men, however this effect was attenuated following adjustment. In addition to conventional risk factors, health status/psychosocial issues may be contributing factors in the risk of re-hospitalization among these young patients.
Abstract 18813: Outcomes of Patients with Congenital Heart Disease following Heart Transplantation: the Impact of Disease Type, Prior Thoracic Surgeries and End-Organ Dysfunction
Authors: Lewis Matthew J , Ginns Jonathan , Schulze P. C , Lippel Matt , Chai Paul , Bacha Emile , Mancini Donna , Rosenbaum Marlon , Farr Mary Jane
Published: July 2021

Introduction:
Adults with congenital heart disease (ACHD) are at increased risk for early adverse outcomes following heart transplantation (Htx). Despite the need for improved risk stratification, small cohorts have constrained identification of patient-specific factors associated with poor prognosis. We hypothesized that type of CHD, number of sternotomies and prior end-organ dysfunction would be associated with an increased risk for mortality post-HTx.

Methods:
We performed a retrospective, observational cohort study of all patients with ACHD who underwent HTx at our institution from 1/1997 to 1/2014. The primary endpoint was death. Exposures of interest included type of CHD, number of sternotomies and hepatic dysfunction secondary to passive congestion, measured as high Models for End-Stage Liver Disease Excluding INR (MELD-XI) score.

Results:
48 ACHD patients were followed (mean age at HTx: 36±1.7 years). Diagnoses included: Tetralogy of Fallot (TOF)/pulmonary atresia/double outlet right ventricle in 15 (31%), D-transposition of the great arteries in 10 (21 %), tricuspid atresia/double inlet left ventricle in 9 (19%), VSD/ASD in 4 (8%), heterotaxy in 3 (6%), congenitally corrected transposition of the great arteries in 2 (4%), and 5 (10%) with other diagnoses. Pre-transplant cardiac surgeries included: Fontan operation in 12 (25%), Mustard/Senning repair in 9 (19%), TOF repair in 5 (11%), Rastelli repair in 5 (11%), VSD/ASD closures in 3 (6%), other another congenital heart surgery in 8 (17%) and no prior cardiac surgery in 5 (11%).

Over a median follow-up time of 3.9 years, 14 patients died (29%) and 10 (71%) deaths occurred within 30 days of HTx. Survival at 1 and 5 years was 77%. Deaths within 30 days of surgery were secondary to hemorrhage in 4 (40%), graft failure in 3 (30%) and multi-system organ failure in 3 (30%). By multivariate analysis, ≥3 sternotomies (HR 8.5, p=0.02), MELD-XI score >18 (HR 6.2, p=0.009) and heterotaxy (HR 9.8, p=0.01), were significant predictors of mortality.

Conclusion:
In our cohort of patients with CHD undergoing Htx, ≥3 sternotomies, MELD-XI score >18 and heterotaxy syndrome were significantly associated with death. These findings may be important in patient selection and timing of Htx in this population.
Abstract 18833: Annulus Preservation Strategy Improves Late Outcomes in Tetralogy of Fallot: An Anatomical Equivalency Study
Authors: Pondorfer Prisca , Yun Tae-Jin , Cheung Michael , Ashburn David , Manlhiot Cedric , McCrindle Brian , Mertens Luc , Grosse-Wortmann Lars , Redington Andrew , Van Arsdell Glen
Published: July 2021

Introduction:
Late outcome of repaired TOF is driven by the impact of residual lesions. We shifted strategy from liberal transannular patch (TAP) use to aggressive valve and annulus preservation (AP) hypothesizing that for equivalent anatomy, AP would leave a mixed stenosis regurgitation lesion that would lead to a healthier right ventricle (RV).

Methods:
Between 1996 and 2002, 185 children underwent TOF repair (median age 7.7 m). A regression equation for predicting annulus preservation, in the AP group, was derived from preoperative anatomic parameters and applied to all. Patients were identified (n=107) that could have had either AP or TAP on the basis of anatomical equivalency (subgroup validation with propensity matching) with 52 having a TAP and 55 having AP. These are the primary study group.

Results:
Cardiac MRI at mean age 13.1±2.3 yrs (TAP n=28, AP n=23) showed AP was associated with significantly lower indexed RV end diastolic vol (AP: 120±29; TAP: 181±35 mL - Fig. 1), RV end systolic vol (AP: 57±23; TAP: 95±25 mL), RV stroke volume (AP: 64±15; TAP: 86±15 mL), MPA regurgitant fraction (AP: 28±11; TAP: 45±9 %), all p<0.0001, and LV mass (AP: 46±6; TAP: 54±8 gm/m2); p=0.001). Echo RVOT gradient was no different (AP 31 Vs TAP 25 mmHg (p=ns). MRI LVEF (AP: 57±4; TAP: 55±4 %; P=0.031) and RVEF (AP: 54±7; TAP: 48±6 %; p=0.004) was higher after AP. Freedom from surgical reintervention at 15 years was 89.3% (TAP) and 71.7% (AP , P=0.048) (Fig.2) with early reoperation for RVOTO predominating in AP and late pulmonary valve replacement most frequent in TAP. VO2 max for all AP vs TAP was higher in AP (p<0.05).

Conclusion:
This is the first long-term follow-up study demonstrating that, for equivalent anatomy, an aggressive AP strategy leads to a lower reoperative incidence, less pulmonary insufficiency, smaller indexed RV volumes and better LV function as compared to a standard TAP. Surgical strategy directly impacts ventricular health and should be reflected in practice.
Abstract 18836: Differences in Cardiopulmonary Exercise Test Data and Prognosis in Black and White Men with Heart Failure: the Henry Ford HospITal CardioPulmonary EXercise Testing (FIT-CPX) Project
Authors: Saval Matthew A , Brawner Clinton A , Shafiq Ali , Aldred Heather E , Hassan Raakesh , Vasko Stephanie , Ehrman Jonathan K , Selektor Yelena , Tita Christina , Velez Mauricio , Williams Celeste T , Lanfear David E , Keteyian Steven J
Published: July 2021

Introduction:
Numerous metrics from the cardiopulmonary exercise test (CPX) are associated with outcomes among patients with heart failure with reduced ejection fraction (HFrEF). Among patients with HFrEF, mortality rates differ by race; however, the influence of race on the association between common measures obtained during CPX and mortality has not been fully described.

Purpose:
Retrospective analysis to describe the relationship between key CPX measures and the composite endpoint of mortality, left ventricular assist device (LVAD), or cardiac transplant (CT) in white and black men with HFrEF.

Methods:
Self-identified white and black male patients (n= 761; age= 55 ± 12 y; BMI= 30.6±6.6) with a CPX between 1997 and 2010 and confirmed HFrEF (ejection fraction [EF] ≤ 40%) were identified. Endpoint data was obtained through 2011. The association with the composite endpoint was evaluated separately for 7 key CPX measures with adjustment for age, hypertension, beta-blocker therapy, EF, and ischemic etiology using Cox regression stratified by race.

Results:
During a median follow-up of 3.5 y there were 195 (54%) and 193 (48%) events for white and black patients, respectively. All CPX variables were associated (p<0.05) with the composite endpoint in both white and black patients (Table). The greatest Wald statistic among white patients was % predicted peak oxygen uptake (ppVO
2
) at 76.2, and among black patients it was ventilatory efficiency (V
E
-VCO
2
slope) at 90.8.

Conclusion:
Among white and black male patients, % predicted peak VO
2
and V
E
-VCO
2
slope, respectively, were most strongly associated with the combined end point of mortality, LVAD or CT. These data suggest that risk stratification using CPX variables may differ by race. Further research is needed to determine if race-specific methods of CPX-based risk stratification are needed.
Abstract 18852: Myofilament Length Dependent Activation: Role of Titin
Authors: AIT MOU Younss , Hsu Karen H , Greaser Marion , Irving Thomas C , deTombe Pieter P
Published: July 2021

The cellular basis of the Frank-Starling mechanism is sarcomere length (SL) modulation of myofilament Ca
2+
sensitivity (LDA). The molecular mechanism(s) that underlie LDA are unknown, but recent evidence has implicated the giant protein titin as possible sarcomeric strain sensor responsible for LDA by an, as of yet unidentified, signal transduction pathway. Accordingly, the aim of the present study was to elucidate the impact of SL (from slack=2.0 μm to stretch=2.4 μm) on LDA and sarcomere structure in isolated rat myocardium from either wild-type (WT) or mutant (HM) rats expressing a giant splice isoform of titin. At stretch, WT muscles showed reduced increase in passive tension (-20%) and twitch force (-58%); also, LDA was significantly blunted at the myofilament level. Time-resolved small angle x-ray diffraction of intact twitching muscles during diastole revealed at stretch a significant increase in intensity and spacing of: myosin M2 (+121% & +0.4%) and troponin T3 (+174% & +1.0%); Myosin binding protein C (MyoBPC) also trended to increase (C1%C2). These SL dependent changes in sarcomere structure were absent in HM muscles. Cross-bridge radial spacing (layer line analysis) was significantly reduced at stretch in WT (-8.0%); in HM muscles radial spacing was further, but similarly reduced at both slack and stretch (~-20%). Equatorial spacings and intensity ratios were similar between WT and HM at both slack and stretch. Electron density reconstruction revealed, only in WT, increased mass in both thick and thin filament, and the appearance of an as of yet unidentified moiety spanning the space between the thick and thin filaments at stretch. These results were independently confirmed in skinned myocyte fragments in which endogenous TnC was replaced with fluorescently labelled TnC.

Conclusion:
Stretch induces structural changes in both thick and thin filaments mediated by titin strain. Moreover, MyoBPC may interact with actin to mediate LDA.
Abstract 18865: Identification of a Functional SNP Regulating PRRX1 at the 1q24 Locus for Atrial Fibrillation
Authors: Dolmatova Elena , Tucker Nathan R , Lin Honghuang , Cooper Rebecca R , Ye Jiangchuan , Sinner Moritz F , Imakaev Maxim , Lubitz Steven A , Leyton-Mange Jordan , Vlahakes Gus , Benjamin Emelia J , Lunetta Kathryn L , Mirny Leonid , Milan David J , Ellinor Patrick T
Published: July 2021

Introduction:
Genome-wide association studies have identified 9 genomic loci associated with atrial fibrillation (AF).

Hypothesis:
We sought to identify the functional variant at the 1q24 locus for AF, located upstream of the paired related homeobox 1 gene (
PRRX1
).

Methods:
We used morpholino-mediated knockdown in zebrafish to assess the role of
PRRX1
in cardiac function and development. To identify potential enhancers at the
PRRX1
locus we analyzed DNase hypersensitivity, histone methylation, and mammalian conservation data from ENCODE. Tissue-specific enhancer activity was evaluated by microinjection of eGFP reporter constructs for each putative enhancer into zebrafish and luciferase assays in a mouse atrial myocyte (HL-1) cell line. To determine physical interaction between the AF-associated enhancer and
PRRX1
promoter we analyzed available Hi-C data and performed chromatin conformation capture (3C). The functional SNP was localized using luciferase assays in HL-1 cells. The effect of the functional SNP on gene expression in human left atrial tissue was measured by qPCR.

Results:
Knockdown of the
PRRX1
ortholog in zebrafish resulted in atrial dilation and shortening of atrial action potential duration (APD
80
: 114.8±2.2ms vs 126±1.5ms in controls, p=0.0004). Of the 4 regions tested at the 1q24 locus, 2 adjacent regions exhibited enhancer activity in the zebrafish myocardium. 3C demonstrated an increased interaction frequency between the enhancer and
PRRX1
promoter regions in cells of cardiac lineage when compared to controls (103±57%, p=0.038). Screening for functional SNPs within these regions revealed that the AF risk allele (C) at SNP rs577676 associated with ~4 fold increased enhancer activity as compared to the non-risk (T) allele in HL-1 cells. Finally, regional eQTL analysis of human atrial tissue showed that rs577676 correlated with
PRRX1
expression.

Conclusions:
We have implicated
PRRX1
in cardiac electrophysiology by demonstrating that knockdown of the gene results in atrial dilation and shortening of atrial action potential duration. Further, we have found that SNP rs577676 modifies an enhancer regulating
PRRX1
expression.