bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 835: Downregulation Of Cardiomyocyte-enriched Micrornas Contributes To Altered Gene Expression In Heart Failure
Authors: Ikeda Sadakatsu , Kong Sek Won , Lu Jun , Bisping Egbert , Bodyak Natalya , Lee Kyu-Ho , Ma Qing , Kang Peter M , Pieske Burkert , Allen Paul D , Golub Todd , Pu William T
Published: July 2021

Background:
MicroRNAs (miRNAs) are a novel class of non-coding RNAs that regulate gene expression posttransciptionally. Altered miRNA expression has been implicated in diverse human diseases such as cancer. Accumulating evidence suggests the importance of miRNAs in the heart. However, the contribution of miRNAs to heart disease remains incompletely understood.

Methods and Results:
We measured the expression of 261 miRNAs in heart failure resulting from transgenic overexpression of calcineurin. 59 miRNAs were confidently detected in the heart, and 11 miRNAs belonging to 6 families (miR-1, -15, -30, -133, -195, -208) were downregulated compared to non-transgenic control (Welch’s t-test nominal p<0.05, false discovery rate <0.001). The results were validated by qRTPCR. There was no upregulated miRNA. Four of these miRNAs (miR-1, -30, -133, -208) were enriched in a purified cardiomyocyte preparation, compared to non-myocytes. Downregulation of these four miRNAs was reproduced in purified failing versus non-failing cardiomyocytes. This excluded artifactual downregulation from reduced myocyte fraction in failing hearts. The remaining two miRNAs (miR-15, and -195) were exclusively expressed in non-cardiomyocytes and did not changed in failing cardiomyocytes. Next, we used Affymetrix expression profiling to show that the predicted targets of these downregulated miRNAs were disproportionately upregulated compared to the entire transcriptome (Fisher’s exact p < 0.001). This suggests an association between downregulation of these miRNAs and upregulation of predicted target genes in heart failure. One particularly intriguing target of the predominant cardiac microRNA miR-1 is calmodulin, a key regulator of calcium signaling. We showed that calmodulin and downstream calmodulin signaling to NFAT is regulated by miR-1 in cultured cardiomyocytes.

Conclusion:
Our results indicate that altered expression of cardiomyocyte-enriched miRNAs may contribute to abnormal gene expression in heart failure. The regulation of calmodulin and calcium signaling by miR-1 suggests a mechanism by which miR-1 may regulate heart function.
Abstract 1018: Cardiac Progenitor Cells and Biotinylated IGF-1 Nanofibers Improve Endogenous and Exogenous Myocardial Regeneration after Infarction
Authors: Misao Yu , Davis Michael E , Segers Vincent E , Rota Marcello , Esposito Grazia , Mosna Federico , Gatti Alessandro , Hosoda Toru , Urbanek Konrad , Leri Annarosa , Anversa Piero , Lee Richard T , Kajstura Jan
Published: July 2021

Cardiac progenitor cells (CPCs) possess the IGF-1-IGF-1 receptor system which promotes cell survival, growth and differentiation. Therefore, we tested whether the local injection of CPCs together with the prolonged release of IGF-1 by self-assembling peptides enhanced myocardial regeneration after infarction. The possibility was raised that this strategy may improve cardiac repair by potentiating the regenerative response of the delivered and resident CPCs. Myocardial infarction was induced in rats and after the injection of 100,000 clonogenic immunocompatible EGFP-positive-CPCs in the border zone, biotinylated IGF-1 nanofibers were delivered to the same region. Four groups of animals were used for comparison: infarcted hearts injected with peptide only, infarcted hearts injected with CPCs only, untreated infarcted hearts and sham operated hearts. All animals received BrdU throughout the 1 month experimental period for the recognition of newly formed cells. Infarct size, ~60%, was comparable in the 4 groups. Although all treated-infarcted hearts showed a reduction in chamber volume and an increase in wall-thickness-to-chamber volume ratio and LV mass-to-chamber volume ratio, the combined treatment had the most positive effect. Similarly, LVEDP, LVDP, and dP/dt improved predominantly in infarcted hearts exposed to CPCs and IGF-1 which possessed a larger number of regenerated myocytes. The newly formed BrdU-positive myocytes consisted of EGFP-positive and EGFP-negative cells. The former category corresponded to the progeny of the injected CPCs and the latter was the product of differentiation of resident CPCs. The regenerated myocytes showed a high degree of differentiation; 20% of myocytes had a volume 2,000 –10,000 μm
3
. This level of maturation was not observed in infarcted hearts treated only with CPCs or IGF1 releasing peptides. Also, administration of CPCs and IGF-1 led to the formation of numerous resistance arterioles and capillary structures within the regenerated myocardium. Thus, the combination of CPCs and IGF-1 biotinylated nanofibers results in an unprecedented degree of myocardial recovery of structure and function after infarction. Importantly, the regenerated myocytes acquire the differentiated adult phenotype.
Abstract 1055: The 70 kDa Heat Shock Cognate Protein Plays A Novel Role In Myocardial Chemokine Expression And Cardiac Dysfunction Following Ischemia And Reperfusion Injury
Authors: Zou Ning , Ao Lihua , Yang Xiaoping , Su Xin , Fullerton David A , Meng Xianzhong
Published: July 2021

Myocardial ischemia and reperfusion (I/R) causes the release of cellular proteins including heat shock proteins (HSPs). The inducible HSP70 induces cytokine production in monocytes and dendritic cells through Toll-like receptor 4 (TLR4) signaling. In evaluation of the role of HSPs in myocardial inflammatory response in a mouse heart global I/R model, we found that the 70 kDa heat shock cognate protein (HSC70), but not HSP70, was released into the extracellular space and the coronary effluent during I/R. These observations prompted us to
hypothesize
that HSC70 plays a novel role in postischemic myocardial inflammatory response and cardiac dysfunction.

Methods:
We subjected mouse hearts to global I/R (20 min/60 min) or perfusion using the Langendorff method. We examined:

the effect of HSC70 antibody on myocardial chemokine expression and cardiac functional recovery following I/R,

the effect of recombinant HSC70 on myocardial chemokine expression and cardiac function and

the role of TLR4 and the HSC70 substrate-binding domain in the effect of HSC70 on the heart.

Results:
In comparison with non-immune IgG, anti-HSC70 reduced myocardial expression of KC and MCP-1 mRNAs and proteins following I/R. Moreover, treatment with anti-HSC70 improved postischemic cardiac functional recovery (66±5.4% of baseline vs. 28±5.1% of baseline in hearts treated with non-immune IgG, p<0.01). Recombinant HSC70 induced myocardial expression of KC and MCP-1 mRNAs and proteins and caused cardiac dysfunction (72±2.6% of baseline vs. 98±3.9% of baseline in perfusion controls, p<0.001) in hearts with competent TLR4 (C3H/HeN). Interestingly, these effects of HSC70 were abrogated in hearts with defective TLR4 (C3H/HeJ). The potency of HSC70 was completely lost in the absence of its substrate-binding domain.

Conclusions:
Taken together, our studies demonstrate, for the first time, that HSC70 plays an important role in the induction of myocardial chemokines and cardiac dysfunction during I/R. The effect of HSC70 is dependent on TLR4 and requires the presence of the substrate-binding domain. The results suggest that the release of HSC70 into the extracellular space elicits an inflammatory response and causes mechanic dysfunction in the heart.
Abstract 1064: Pellino-1: A Novel Candidate In Vegf/Flk-1/MKK2 Signaling In Ischemic Preconditioning Induced Cardioprotection: A Study Using Flk +/− and MKK2 −/− Knockout Mice.
Authors: Thirunavukkarasu Mahesh , Samuel Samson Mathews , Addya Sankar , Zhan Lijun , Huang Chi-Kuang , Gaestel Matthias , Menon Venogopal P , Maulik Nilanjana
Published: July 2021

VEGF modulates the complex process of angiogenesis and other various aspects of endothelial cell function through either of its two tyrosine kinase receptors, VEGFR1/Flt-1 or VEGFR2/Flk1/ KDR via its target protein MKK2. In the present study we used Flk1 +/− and MKK2 −/− knockout mice in an attempt to address an important clinical issue by identifying potential downstream candidates of VEGF signaling through Flk1 receptor that trigger cardioprotective signal during ischemic preconditioning (IP). Mouse hearts were subjected to 30 min of global ischemia and 2 hours of reperfusion (IR) in the Isolated Working Heart model. It is known that IP (4min of ischemia + 6min reperfusion, 4 cycles, before 30 min of ischemia) induces cardioprotection through the activation of the VEGF signaling cascade. The mice were randomly divided into 6 groups for both the gene knockout (KO) studies:

Wild Type-Baseline (WTBL),

FlkBL/ MKK2BL (KOBL),

WTIR ,

KOIR,

WTIP and

KOIP.

Significant reduction in left ventricular functional recovery through out reperfusion (dp/dt = 605 vs 884), diminished coronary flow (1.9 vs 2.4) and aortic flow (0.16 vs 1.2) and increased infarct size (38.4% vs. 28.41%) after reperfusion were observed in FlkIR, compared to WTIR. As expected we observed disruption in IP induced cardioprotection in FlkIP compared to WTIP. Affymetrix gene chip analysis demonstrated significant downregulation of genes (Pellino-1, MKK2, NF-Î°B) which are thought to play important roles in cardioprotection after ischemic insults in the Flk +/− mice compared to WT. These results were further validated at the mRNA expression level with Real Time PCR. Pellino-1 (Pel-1) was found to be significantly downregulated in FlkBL (0.74 vs 1), FlkIR (1.29 vs 1.35) and FlkPC (1.35 vs 1.49) as compared to their respective controls. We further validated the mRNA levels of Pel-1using Real Time PCR and RT-PCR in the MKK2 −/− mice and found that it, remained unaffected in MKK2BL as compared to its WTBL, and increased as expected in MKK2PC as compared to both MKK2BL and FlkPC (2.48 vs 1.2 and 2.48 vs 1.35, respectively). Therefore this study validated for the first time that Pel-1 is a novel downstream mediator in VEGF/FLK1 signaling and it induces IP mediated cardioprotection via MKK2 signaling.
Abstract 1351: Ca
2+
Dissociated from Myofilaments Enhances Delayed Afterdepolarizations by Triggering Ca
2+
Waves in Rat Cardiac Muscle
Authors: Miura Masahito , Wakayama Yuji , Shimokawa Hiroaki
Published: July 2021

Background:

Non-uniform excitation-contraction coupling (ECC) causes arrhythmias by triggering Ca
2+
waves from the border zone (BZ) between contracting and stretched regions. To elucidate the triggering mechanism of Ca
2+
waves under the condition of non-uniform ECC, we examined the role of Ca
2+
dissociated from myofilaments in delayed afterdepolarizations (DADs) and Ca
2+
waves.

Methods:

Force was measured in 25 rat trabeculae with a strain gauge, sarcomere length with a laser diffraction technique, membrane potential with a ultracompliant microelectrode, and [Ca
2+
]
i
with microinjected fura-2 and a CCD camera. To produce non-uniform ECC, a restricted region (~300 μm length) of muscle was exposed to a jet of Hepes solution containing 20 mM 2,3-butanedione monoxime (BDM), causing sarcomere stretch inside the region during twitches. DADs were induced by 7.5 s-2 Hz stimulus trains in the presence or absence of the BDM jet. Streptomycin (100 μM) was then added to eliminate the effect of stretch-activated channels. To modulate myofilament-Ca
2+
affinity inside the BDM jet region, muscle length was varied transiently from 2.0 to 2.1 or 2.2 μm during a twitch by the last stimulus of the trains (24 °C, [Ca
2+
]
o
=2.0 mM).

Results:

The regional exposure of muscle to the BDM jet reduced the twitch force by 41 %, but enhanced DADs (n=6, P<0.05) and aftercontractions (n=6, P<0.05) and occasionally induced action potentials. Streptomycin did not suppress the significant enhancement of DADs and aftercontractions caused by the BDM jet (n=6). Stretch of sarcomere length for 210 ms increased the velocity of Ca
2+
waves and the amplitude of aftercontractions in proportion to the increase in force during the stretch (n=12, r=0.90, P<0.01). In the presence of 1 mM caffeine, quick return of muscle length after the stretch for 400 ms induced a small and quick increase in [Ca
2+
]
i
at BZ, whose amplitude was correlated with the change in force during the stretch (n=15, r=0.76, P<0.01).

Conclusions:

These results suggest that Ca
2+
dissociated from myofilaments due to quick release of active sarcomere enhances DADs by triggering Ca
2+
-induced Ca
2+
release in the BZ and thereby induces triggered arrhythmias. Thus, non-uniform ECC can be arrhythmogenic by the dissociated Ca
2+
in the BZ.
Abstract 1368: BK Channel β1 Subunits Are Specific Effectors Of Cholane-induced Channel Activation
Authors: Bukiya Anna , Toro Ligia , Dopico Alejandro M
Published: July 2021

The activity of large conductance, Ca
2+
- and voltage-gated potassium (BK) channels in smooth muscle critically controls vascular tone. Depolarization-induced Ca
2+
-entry in the myocyte activates BK channels, which generate outward positive current that tends to repolarize the membrane, limit Ca
2+
entry and, thus, oppose contraction. Cholane-derived steroids (e.g., lithocholic acid, LC) reduce vascular tone in isolated, resistance-size rat cerebral arteries by selective activation of myocyte BK channels. In most tissues, native BK channels consist of pore-forming α (encoded by
KCNMA1
or
Slo1
) and accessory β1–4 (encoded by
KCNMB1–4
) subunits. Remarkably,
KCNMB
expression is tissue-specific: while
KCNMB1
is highly predominant in smooth muscle,
KCNMB2–4
are not. Thus, agents that target BK β1 subunits may be used to selectively modulate myocyte BK channel function. After cloning the BK α subunit from rat cerebral artery myocytes (termed “cbv1”,
AY330293
), we demonstrated that homomeric cbv1 channel steady-state activity (NPo) was not affected by acute LC application. In contrast, heteromeric cbv1+β1 channel NPo was reversibly increased by LC (+290% of control at EC
max
~150 μM; EC
50
=46 μM). Whether the other BK β subunits (2–4) can substitute for β1 to evoke LC-sensitivity in the BK channel remains unknown. To test this, we applied 150 μM LC to the intracellular side of inside-out patches excised from
Xenopus laevis
oocytes expressing cbv1 alone or cbv1 with a given BK β subunit subtype (1–4). Currents were evoked with the membrane clamped at ±20mV and free Ca
2+
i
set to 10 μM, a concentration found in the cerebral artery myocyte during contraction. As previously found, LC consistently failed to increase homomeric cbv1 NPo, while drastically enhancing heteromeric cbv1+β1 channel NPo. Remarkably, LC failed to activate cbv1+β2, cbv1+β3 and cbv1+β4 heteromeric channels. In conclusion, the BK β1 (smooth muscle-type) subunit serves as a unique sensor for cholane-derived steroids. Thus, these compounds provide a platform for designing therapeutic agents to treat cardiovascular disease where reduction of vascular tone is required.
Abstract 1378: NFkb Blockade Attenuate Cytokines And Oxidative Stress In The Paraventricular Nucleus And Decreases Neurohumoral Excitation In Spontaneously Hypertensive Rats
Authors: Mariappan Nithya , Elks Carrie , Haque Masudul , Ebnezer Philip J , McIIwain Elizabeth , Kerut Edmund K , Francis Joseph
Published: July 2021

The transcriptional factor, nuclear factor kappa B (NFkB) plays an important role in the regulation of cytokines. Among the cytokines, tumor necrosis factor-alpha (TNF) plays an important role in cardiovascular pathophysiology. This study was done to determine whether TNF-α blockade with etanercept (ETN) or NFkB blockade with dithiol pyrolidine thiocarbamate (PDTC) attenuate oxidative stress in the paraventricular nucleus (PVN) and contribute to neurohumoral excitation in spontaneously hypertensive rats.

Method:
Male 20 week old SHR rats were treated with ETN (1 mg/kg BW, sc) or PDTC (100mg/kg BW, ip) for 5 week period. Left ventricular function was measured at baseline (20 weeks) and at 25 weeks using echocardiography. Blood pressure was measured at weekly intervals throughout the study. At the end of the protocol rats were sacrificed the PVN was microdissected for the measurement of cytokines, oxidative stress markers using real time PCR (fold increase compared to WKY controls) and by immunohistochemistry. Superoxide, total reactive oxygen species and peroxynitrite were measured in the PVN and LV using electron paramagnetic resonance. Plasma norepinephrine and epinephrine an indicator of neurohumoral excitation was measured using HPLC-EC.

Results:
PVN data are tabulated. SHR animals had increased expression of protein and mRNA for cytokines and oxidative stress markers in the PVN and LV with increased MAP and cardiac hypertrophy when compared to WKY rats. Treatment with ETN and PDTC attenuated these increases with PDTC showing marked effect than ETN on hypertrophy and blood pressure responses.

Conclusion:
These findings suggest that cytokine activation in the PVN contributes to increased oxidative stress and neurohumoral excitation in hypertension.
Abstract 1500: Gender Differences of Arteriosclerotic Cardiovascular Diseases in Mice Lacking All Nitric Oxide Synthase Isoforms
Authors: Nakata Sei , Tsutsui Masato , Shimokawa Hiroaki , Suda Osamu , Sabanai Ken , Yatera Yasuko , Shibata Kiyoko , Morishita Tsuyoshi , Tasaki Hiromi , Nakashima Yasuhide , Yanagihara Nobuyuki , Otsuji Yutaka
Published: July 2021

Background

: We have recently succeeded in developing mice lacking all 3 nitric oxide synthase (NOS) isoforms (triply n/i/eNOS-KO mice) (
PNAS
2005). Our preliminary study has revealed that those mice spontaneously develop cardiovascular diseases, including hypertension, dyslipidemia, and myocardial infarction (MI), and that there seems to be a great gender difference in those disorders.

Methods and Results

: Experiments were performed in both genders of wild-type (WT) and triply-KO mice. In male mice, survival rate at 11 months of age was markedly more reduced in triply-KO mice than in WT mice (15% vs. 100%,
P
<0.001, n=34 – 41), whereas in female mice, the survival rate was slightly but significantly more reduced in triply-KO mice than in WT mice (74% vs. 100%,
P
<0.05, n=34–38). There was a significant gender difference in the survival rate in the triply-KO mice (male 15% vs. female 74%,
P
<0.05). A postmortem examination revealed that both genders of the triply-KO mice died mainly due to spontaneous MI associated with severe coronary arteriosclerosis (n=13–20). However, in the female triply-KO mice, as compared with the male triply-KO mice, the incidence of MI (29% vs. 56%,
P
<0.05) and the extent of coronary lesions (intima/media ratio, 0.15±0.01 vs. 0.01±0.01,
P
<0.05) were both significantly less. In addition, although both genders of the triply-KO mice exhibit hypertension (HT) and hyper-low density lipoproteinemia (hyperLDL), the extents of both HT (135±2 vs. 150±3 mmHg) and hyperLDL (20.6±3.9 vs. 29.4±7.9 mg/dl) were again significantly less in the female than the male mice (both
P
<0.05, n=6–10). Importantly, ovariectomy significantly exacerbated both HT (159±3) and hyperLDL (32.1±8.8) in the female triply-KO mice (both
P
<0.05, n=6–7). Furthermore, treatment with 17β-estradiol (10
−8
M, 2 days) significantly enhanced prostacyclin production in isolated aortas of the triply-KO mice (3.07±0.44 to 6.56±0.56 nM/g,
P
<0.05, n=5), suggesting a novel NO-independent anti-atherogenic action of estrogen.

Conclusions

: These results provide the first evidence that the gender difference in the extent of arteriosclerotic cardiovascular diseases still exists even in the complete absence of NOSs system, in which estrogen may, at least in part, be involved.
Abstract 1541: Atypical Atrioventricular Nodal Reentrant Tachycardia with Anterior Retrograde Slow Pathway: Incidence, Electrophysiological Characteristics and Effect of Slow Pathway Ablation
Authors: Otomo Kiyoshi , Nagata Yasutoshi , Taniguchi Hiroshi , Uno Kikuya , Iesaka Yoshito
Published: July 2021

BACKGROUND: Atypical AV nodal reentrant tachycardias (AVNRT) usually exhibit earliest retrograde atrial activation (ERAA) at the right posteroseptum (Rt-PS) or proximal coronary sinus (PCS). However, previous studies have shown that atypical AVNRT could rarely exhibit ERAA at the right anteroseptum (Rt-AS). The purpose of this study was to elucidate the incidence, characteristics and effect of slow pathway (SP) ablation in atypical AVNRT with an anterior retrograde SP.

METHODS: The electrophysiological and ablation data were reviewed in 360 AVNRTs induced in 340 consecutive patients. Atypical AVNRT was differentiated from typical form by a longer H-A interval during ventricular pacing at the tachycardia cycle length (TCL) (HAp: =/>70ms), and evidences for a lower common pathway (LCP), including second-degree AV block without tachycardia interruption, HAp longer than the HA interval during tachycardia (HAt). Atypical AVNRTs were classified into two types; the posterior type with ERAA at the Rt-PS or PCS; and anterior type with ERAA at the Rt-AS.

RESULTS: In a total of 360 AVNRTs, there were 300 typical (83%) and 60 atypical forms (17%). Among the 60 atypical forms, 51 (14%) were classified into the posterior type, while the remaining 9 (3%) were classified into the anterior type. The anterior type of atypical AVNRT (TCL: 322+/−37ms) exhibited ERAA at the Rt-AS during the tachycardia and ventricular pacing, shorter A-H interval (162+/−39ms), longer HAt (167+/−40 ms), longer HAp (184+/−53ms), and evidences for a LCP, including a second-degree AV block during the tachycardia (n=4) and HAt being shorter than the H-Ap (n=9). All posterior types of atypical AVNRT were rendered non-inducible after an ablation to the ERAA site. In anterior type, the conventional SP ablation at the Rt-PS did not eliminate any of the 9 tachycardias; however, ablations at the right midseptum eliminated 7 (78%) of the 9 anterior types of atypical AVNRT.

CONCLUSION: Atypical AVNRT with an anterior retrograde SP was observed in 3% of all AVNRTs. Conventional Rt-PS ablation was ineffective; and the midseptal ablation was modestly effective in this entity. The tachycardia circuit of the anterior type might be deviated to more anterior part of the Koch’s triangle than that of the posterior type.
Abstract 1631: Exclusion of Coronary Artery Stenosis by Non-invasive Coronary Angiography Using Multislice Computed Tomography Determines a Good Long-term Prognosis in Patients With Chest Pain - Follow-Up Study in 1017 Patients
Authors: Steinbigler Peter , Böhme Eike , Weber Carla , Czernik Andreas , Buck Jürgen , Haberl Ralph
Published: July 2021

Long-term prognosis following exclusion of coronary artery stenosis by noninvasive coronary angiography using multislice computed tomography (MSCT) up to now has not been determined. We therefore performed noninvasive coronary angiography using MSCT (Philips Brilliance, 4 – 64 slices, retrospective ECG gating, 0.625mm collimation, 0.4sec gantry rotation time) in 1017 consecutive patients (657 male, 360 female, age 64±11years, 240 patients with known coronary artery disease (CAD)) referred to MSCT-study with chest pain. Patients with acute coronary syndromes, stents, atrial fibrillation and calcium scores > 1500 were not included. Based on MSCT results invasive study was recommended or not. All patients or the referring clinician were contacted by telephone or mail at least 6 months after their scan. Diagnostic image quality could be obtained in 992/1017 (98%) patients. In 620 of 992 patients (=63%) coronary artery stenosis could be excluded and invasive study was not recommended. Despite these recommendations invasive study was performed due to other clinical indications in 83/620 patients within < 30 days and in 43/537 patients within > 30days after the scan. Only in 13/126 patients stenoses >50% were found but no treatment was necessary. During the mean follow-up period of 612±192days 7/620 patients died but no patient suffered from cardiac death or acute myocardial infarction. In 372 of 992 patients invasive coronary angiography was recommended and performed in 230 patients (n=167 within < 30days, n=63 within >30days). In 165/230 patients stenoses >50% were found, treated by angioplasty or stents in 139/165 patients. During the mean follow-up period of 602±161days 11/372 patients died, two patients suffered from sudden, two patients from non-sudden cardiac death and one patient survived acute myocardial infarction. Thus, exclusion of coronary artery stenoses by noninvasive coronary angiography using multislice computed tomography determines a good lomg-term prognosis in patients with chest pain.
Abstract 1662: Arrhythmic Events During the 40/90 days “Cooling Off” Period: Clinical Utility of the Wearable Defibrillator
Authors: Choudhuri Indrajit , Tverskaya Rozalia , Kazanikova Galina , Gluck Jason A , Keller Seth I , Suri Ranjit
Published: July 2021

Background:
A “cooling off” period (COP) of 40 days after MI and 90 days after coronary revascularization or non-ischemic CM (NICM) diagnosis is customary to allow clinical improvement prior to assessing the need for ICD implantation. The COP creates a clinical dilemma that requires balancing ongoing sudden death (SD) risk and the cost of potentially unnecessary ICD implants. We reviewed our wearable defibrillator (WD) experience to assess its clinical utility during this period of uncertainty.

Methods:
Medical records from 27 patients with EF≤35% requiring a COP who were offered WD (LifeVest, ZOLL Lifecor) were reviewed for clinical indication, EF before and after WD use, sudden cardiac arrest (SCA) or treated VT/VF, and subsequent outcome.

Results:
Wearable defibrillator indications were: recent MI (n=7), ischemic CM (ICM) with recent revascularization (n=10), untreated NICM (n=9), and tachycardia-CM (n=1). Twenty-five of 27 patients agreed to WD and 23 complied. Two patients had 3 clinical events: 1 (not wearing WD) was resuscitated from SCA; 1 (treated by WD) survived sustained syncopal VT/VF but later died suddenly not wearing the WD. One patient was shocked for AF. After the COP (n=24), 6/24 (25%) patients had EF>35% (3 ICM and 3 NICM) and no ICD was implanted. Eighteen of 24 (75%) had an EF ≤ 35% and received an ICD. Three of 24 (12.5%) patients that received an ICD ultimately had an EF ≥35% over continued follow-up.

Conclusions:
During the COP, patients with EF ≤ 35% had a 12% clinical event rate (3 events in 25 patients). WD protected patients during this high-risk period but non-adherence was associated with death/cardiac arrest. While ICD implantation was safely avoided in 25%, unnecessary ICD implantation still occurred. Prolonged WD therapy beyond the COP may be more prudent in some to observe for delayed recovery (12%). In patients with newly diagnosed LV systolic dysfunction or after revascularization, risk and recovery are in flux. We suggest that this continuum is not confined to the COP. In patients with low EF, prolonged application of WD may provide additional SD prevention beyond the initial high-risk period and may prevent unnecessary ICD implantation.
Abstract 1966: Comparison of Right Ventricular Strain and Strain Rate in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy, Right Ventricular Outflow Tract Tachycardia, and Matched Controls
Authors: Salehian Omid , Klug Andrew P , Healey Jeffrey , Burwash Ian G
Published: July 2021

Background:
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by fibro-fatty replacement of RV myocardium leading to ventricular tachycardia and sudden death in otherwise healthy individuals. Diagnosis is challenging as there are no diagnostic tests with adequate accuracy. Current diagnosis of ARVC is made by the task force criteria. One of the main diagnostic dilemmas continues to be distinguishing ARVC from a relatively benign entity of right ventricular out flow tract tachycardia (RVOT VT). Assessment of myocardial strain and strain rate has been used to study patients with ischemic heart disease and has shown utility in identifying subtle myocardial dysfunction not detected by routine wall motion assessment. The goal of this study was to compare myocardial strain and strain rates in patients with ARVC, RVOT VT and matched controls.

Methods:
We prospectively enrolled 12 patients with ARVC (based on task force criteria), 10 with RVOT VT, and 22 age and gender matched controls. Echo studies (including tissue Doppler derived myocardial strain echocardiography) were performed with commercially available systems (GE, Vivid 7). Peak systolic RV myocardial strain and strain rate were measured at base, mid, and apical RV free wall and compared.

Results:
ARVC patients had significantly lower peak systolic RV strain compared to both RVOT VT patients and matched controls (Table

). There was also significantly lower peak systolic strain rate at the apical RV myocardium in patients with ARVC compared to both those with RVOT VT (p=0.02) and controls (p=0.01).

Conclusions:
Patients with ARVC have abnormally low RV systolic strain and strain rates when compared to matched controls as well as those with RVOT VT. This modality can be routinely used in assessing patients suspected of ARVC as it might assist in earlier diagnosis as well as help in distinguishing patients with ARVC from those with RVOT VT.

P<0.05 compared to controls,
†
P<0.05 compared to RVOT VT group
Abstract 1987: The site of Thin-cap Fibroatheroma in Native Coronary Arteries: A Three-Vessel Optical Coherence Tomography Study
Authors: Fujii Kenichi , Masutani Motomaru , Okumura Takahiro , Kawasaki Daizo , Akagami Takafumi , Sakoda Tsuyoshi , Masuyama Tohru , Ohyanagi Mitsumasa
Published: July 2021

Background:
Plaque rupture is the most frequent cause of coronary thrombosis such as acute myocardial infarction (AMI). It has been recognized that thin-cap fibroatheroma (TCFA) is the precursor lesion of plaque rupture. It is clinically important to understand the potential sites of TCFA. Therefore, we evaluated the geographic distribution of TCFAs using optical coherence tomography (OCT) that is a high-resolution (approximately 10 μm) imaging modality.

Methods:
We performed three-vessel OCT examinations in 51 patients; 34 AMI and 17 stable angina pectoris (SAP) patients. OCT criteria for TCFA was lipid-rich plaque with cap thickness <65 μm. The distance between each TCFA segment and the respective coronary ostium was measured with motorized OCT transducer pullback. The overall length of the region of interest, subsequently divided into 10mm segments, was 68.2 ± 27.1 mm long (range: 18.9 – 121.1 mm).

Results:
The OCT detected 86 TCFAs in 41 patients: 32 were identified in AMI patients and 9 in SAP patients. Of all TCFAs, 26 were located in the left anterior descending artery (LAD), 16 in the left circumflex artery (LCX), and 44 in the right coronary artery (RCA). Most LAD TCFAs were located between 0 and 40mm from the LAD ostium (96%). Similarly, LCX TCFAs were predominantly located between 0 and 40mm from the LCX ostium (69%). Conversely, RCA TCFAs were evenly distributed in the entire coronary trees. The clustering of the TCFAs was similar in culprit segments compared with non-culprit segments.

Conclusion:
Three-vessel OCT imaging showed that TCFAs tend to cluster in predictable “hot spots” within the proximal segments of the LAD and LCX, and the entire segments of the RCA.
Abstract 306: Deficiency of ROCK1 in Macrophages Protects Against Atherosclerosis
Authors: Wang Hong-Wei , Oyama Naotsugu , Rikitake Yoshiyuki , Kitamoto Shiro , Gitlin Jonathan , Liu Ping-Yen , Liao James K , Boisvert William A
Published: July 2021

Background:
Rho kinases (ROCKs) are serine-threonine protein kinases that regulate various cellular functions. There is increasing evidence that the RhoA/ROCK pathway plays an important pathophysiological role in cardiovascular diseases. However, direct evidence of which ROCK isoforms or target tissues are involved in the atherogenic process is still lacking.

Objective:
The aim of this study was to determine the effect of ROCK1 deficiency on atherogenesis and how ROCK1 affects key atherosclerosis-related macrophage function such as lipid uptake and chemotaxis.

Methods:
We utilized ROCK1
−/−
mice and the atherosclerosis-prone apolipoprotein E knockout (apoE
−/−
) mice or low-density lipoprotein receptor knockout (LDLR
−/−
) mice to investigate the role of ROCK1 in the pathogenesis of atherosclerotic plaque formation. Bone marrow-derived macrophages from ROCK1
−/−
and ROCK1
+/+
mice were used to investigate acetylated (Ac)LDL-mediated foam cell formation and chemotaxis.

Results:
Compared to atherosclerosis-prone apoE
−/−
mice, apoE
−/−
ROCK1
+/−
mice had substantially less fatty streaks foam cells and atherosclerosis (77.0 ± 12.9 × 10
3
μm
2
versus 166.4 ± 14.6 × 10
3
μm
2
,
P <
0.01). Atherosclerotic lesions were reduced also in LDLR
−/−
mice, whose bone marrow were replaced with bone marrow derived from ROCK1
−/−
mice compared to ROCK1
+/+
recipients (181.5 ± 15.6 × 10
3
μm
2
versus 448.5 ± 33.3 × 10
3
μm
2
,
P <
0.05). Bone marrow-derived ROCK1-deficient macrophages exhibited impaired chemotaxis to monocyte chemotactic protein-1 and showed reduced ability to take up lipids and to develop into foam cells when exposed to modified low density lipoprotein.

Conclusion:
These findings indicate that ROCK1 in macrophages is a critical mediator of foam cell formation, macrophage chemotaxis and atherogenesis, and suggest that macrophage ROCK1 may be an important therapeutic target for vascular inflammation and atherosclerosis.
Abstract 2056: Blockade of PDGF Receptor Tyrosine Kinase by Ex Vivo Nano-DDS of Imatinib Mesylate into the Vein Suppresses Vein Graft Neointima Formation
Authors: Kimura Satoshi , Egahira Kensuke , Tsujimoto Hiroyuki , Hara Kaori , Kawashima Yoshiaki , Tominaga Ryuji , Sunagawa Kenji
Published: July 2021

Background:
Clinical outcome of surgical revascularization using autologous vein graft is limited by vein graft failure due to neointima formation. Platelet-derived growth factor (PDGF), expressed by vascular smooth muscle cells (VSMCs), plays a central role in the pathogenesis of vein graft failure. Therefore, optimal nanotechnology-based drug delivery system (Nano-DDS) of PDGF receptor tyrosine kinase (TK) inhibitor, imatinib mesylate (STI571), can be an innovative therapeutic strategy for clinical application. We have developed such Nano-DDS using bioabsorbable PLGA nanoparticles (NP) for local
ex vivo
delivery.

Hypothesis:
Blockade of PDGF receptor TK by Nano-DDS of imatinib suppresses vein graft neointima formation.

Methods and Results:
[studies in human VSMCs in vitro] Addition of fluorescence (FITC)-encapsulated NP resulted in rapid and stable uptake by 99 % of cells. The Nano-DDS of imatinib prevented PDGF-induced phosphorylation of PDGF receptor TK, and thus normalized the PDGF-induced proliferation. [
ex vivo
studies] Incubation of excised rabbit jugular vein and human saphenous vein
ex vivo
in FITC-encapsulated NP for 30 min resulted in highly efficient intracellular delivery rate (> 90 % cells) into cells of the venous wall. [
in vivo
studies in rabbits] The excised jugular vein was treated
ex vivo
with PBS, imatinib only (100 mM), FITC NP only, or imatinib NP (100 mM) (n=5– 6, each) for 30 min, and then interposed into the carotid artery position of hypercholesterolemic rabbits. Seven and 28 days after
ex vivo
FITC NP treatment, FITC-positive cells were detected in many cells in the neointima and media (cellular uptake rate: 60 –70 %). Significant neointima was formed 28 days after grafting in PBS group, which was suppressed in imatinib NP group, but not in FITC NP only or imatinib only groups. Imatinib NP also inhibited the appearance of proliferating PCNA-positive cells and increased phosphorylation of PDGF receptor TK, but did not affect monocyte infiltration or endothelial regeneration process.

Conclusions:
Nano-DDS of imatinib into the excised vein
ex vivo
was feasible and suppressed vein graft neointima formation in rabbits. Nano-DDS of imatinib may be a clinically promising therapeutic strategy for prevention of vein graft failure.
Abstract 2138: Fontan Fenestration Closure Has No Effect On Exercise Capacity But Improves The Ventilatory Response To Exercise
Authors: Meadows Jeffery , Lang Peter , Marx Gerald , Curran Tracy , Sheehan Julie , Rhodes Jonathan
Published: July 2021

Introduction: For patients undergoing Fontan procedures for palliation of single ventricle physiology the addition of a fenestration to the procedure, which permits intracardiac right-to-left shunting, mitigates perioperative morbidity. While some fenestrations may close spontaneously, many remain patent and subject patients to arterial hypoxemia and risk for paradoxical emboli. For this reason fenestration closure is routinely performed post-operatively in the cardiac catheterization laboratory. Fenestration closure typically results in improved arterial oxygenation, but decreased cardiac index. We assessed the hypothesis that sum effect of these physiologic changes would have not improve exercise capacity.

Methods: Nineteen consecutive patients, age 4.8–46 (median 10) years underwent pre and post-fenestration closure exercise testing with expiratory gas analysis.

Results: Prior to fenestration closure, peak oxygen consumption (VO2) was low. Arterial desaturation was present at rest and worsened with exercise. The ventilatory response to exercise was excessive, characterized by elevation of the minute ventilation vs. CO2 production slope (VE/VCO2 slope) and a low end tidal pCO2 at the ventilatory anaerobic threshold (pETCO2). Following fenestration closure, arterial saturation (at rest and at peak exercise) improved significantly. However, there was no change in VO2, heart rate, or oxygen pulse at peak exercise. In contrast, ventilatory abnormalities improved considerably. The VE/VCO2 slope fell 25% and pETCO2 rose from 27.9+/−4.2 to 34.1+/−3.2 mmHg.

Conclusion: Elective Fontan fenestration closure does not improve peak VO2. However, the reduction in right-to-left intracardiac shunting improves arterial oxygen saturation during exercise and reduces the patient’s need to ventilate during exercise. These changes may reduce the Fontan patient’s perception of dyspnea during exercise.

Pre and Post-Fenestration Exercise Data
Abstract 2265: Injection of a Biomaterial Polymer Results in Reverse Remodeling of Displaced Papillary Muscles and Reduction in Acute Ischemic Mitral Regurgitation
Authors: Hung Judy , Solis Jorge , Guerrero J. L , Braithwaite Gavin , Muratoglu Orhun K , Chaput Miguel , Sullivan Suzanne , Fernandez-Friera Leticia , Handschumacher Mark D , Wedeen Van J , Vlahakes Gus J , Levine Robert A
Published: July 2021

Ischemic mitral regurgitation (IMR) relates to papillary muscle (PM) displacement caused by left ventricular (LV) distortion. We tested the hypothesis that displaced PMs can be repositioned by injection of polyvinyl-alcohol (PVA) polymer, a biologically inert material specially formulated to produce an encapsulated, stable, resilient gel once injected into the myocardium. The aim is to alter the compliance of infarcted myocardium and realign the displaced PMs.

Methods
: 9 sheep underwent circumflex branch ligation to produce acute IMR. PVA polymer was then injected by echo guidance into the myocardium underlying the infarcted PM. Hemodynamic data, EF, Elastance (Emax), preload-recruitable stroke work (PRSW), relaxation constant tau, and echo data were measured post IMR and post PVA injection.

Results
: One animal died after coronary ligation and 2 had no IMR; MR was moderate in the remaining 6. PVA injection decreased MR vena contracta from 5±0.4mm to 2±0.7mm (p<0.0001), with decreased tethering distance from infarcted PM to mitral annulus (27±4 to 24±4mm, p<0.001). PVA injection did not significantly decrease EF (43±6% vs 37±4%, post IMR vs post PVA, p=ns), Emax (1.5±0.53 vs 1.6±0.42), PRSW (33±12 vs 31±5) or tau (63±49 ms vs 70±25 ms).

Conclusions
: PVA polymer injection can acutely reverse LV remodeling to reposition displaced PMs and decrease IMR without adverse effects on LV systolic or diastolic function. This new approach (to alter pathologic anatomy) offers an alternative for relieving IMR by correcting PM position, thus relieving tethering that causes IMR.
Abstract 347: eNOS Deficiency Ameliorates Vascular Remodeling Induced by Periadventitial Injury in SOD1 Knock-Out Mice
Authors: Kataoka Keiichiro , Fukuda Masaya , Yamamoto Eiichiro , Nakamura Taishi , Ogawa Hisao , Kim-Mitsuyama Shokei
Published: July 2021

Background:
Copper/zinc SOD (SOD1) is a major enzyme which deactivates superoxide radicals (O2−), and endothelial nitric oxide synthase (eNOS) synthesizes nitric oxide (NO) in endothelial cells. Reduction of each enzyme can increase oxidative stress, leading to cardiovascular dysfunction. Herein, we established SOD1 and eNOS double deficient mice, and examined their physiological and pathological cardiovascular phenotypes to clarify the function of eNOS in cardiovascular system in the case of SOD1 deficiency.

Methods and Results:

SOD1 deficient mice (SOD-KO) were crossbred with eNOS deficient mice (eNOS-KO), and SOD1 and eNOS double-deficient mice (Do-KO) were established. Do-KO had significantly higher blood pressure (BP) than SOD-KO (129.6 ± 4.7 vs. 102.1 ± 1.2 mmHg, p<0.0001). Do-KO had significantly higher heart weights than SOD-KO (3.12 ± 0.09 vs. 2.89 ± 0.03 mg/g, p<0.01). Relaxation of carotid arteries due to acetylcholine was mildly impaired in SOD-KO when compared with wild type mice (WT), while relaxation to acetylcholine was completely ablated in Do-KO. These data indicated that targeted ablation of eNOS in SOD-KO impaired their vascular relaxation, and caused hypertension.

Next, we examined vascular remodeling induced by periadventitial cuff-injuries. Four weeks after cuff replacement, marked neointimal formation was induced in SOD-KO; however, eNOS deficiency in SOD-KO ameliorated the vascular remodeling of SOD-KO, and significantly decreased the ratio of intimal to medial areas (1.23 ± 0.23 vs. 2.23 ± 0.38, p<0.05). This data shows that eNOS enhances the vascular remodeling of SOD-KO caused by cuff injury. NO and O2− react to form the strong oxidant peroxynitrite, which is involved in vascular injury. The levels of 3-nitrotyrosine, a marker of peroxynitrite generation, were significantly elevated in the injured arteries of SOD-KO, while their elevation were attenuated in Do-KO. This indicates that NO derived from eNOS enhances the peroxynitrite formation in injured arteries of SOD-KO, so that vascular remodeling may be markedly enhanced.

Conclusion:
Our results demonstrate that peroxynitrite, generated from O2− and eNOS derived-NO, plays a key role in vascular remodeling induced by periadventitial injury.
Abstract 2373: Diet Plus Pravastatin Treatment Reduces The Risk Of Cardiovascular Disease And Total Mortality In Patients With Metabolic Syndrome: Sub-analysis From A Large-scale Primary Prevention Trial With Pravastatin (MEGA Study)
Authors: Matsushima Teruhiko , Koseki Susumu , Nakamura Haruo
Published: July 2021

Background: The metabolic syndrome is related to an increased risk of cardiovascular disease (CVD), as reported by numerous studies. In this analysis, we investigated the relationship between the metabolic syndrome (MetSyn) and CVD risk in hypercholesterolemic patients and the effect of pravastatin treatment in the MEGA Study population.

Methods: The MetSyn was defined according to modified National Cholesterol Education Program (NCEP) criteria, namely, the presence of three or more risk factors: 1)obesity (body mass index ≥25 kg/m
2
), 2)hypertriglyceridemia (≥150 mg/dL), 3)low HDL cholesterol (<40 mg/dL in men and <50 mg/dL in women), 4)hypertension (SBP≥130 mmHg and/or DBP≥85 mmHg), 5)hyperglycemia (fasting glucose ≥100 mg/dL). The risk of CVD and total mortality was compared in patients with and without MetSyn. The effect of pravastatin plus diet therapy in the patients with MetSyn was compared to those without MetSyn, and moreover these comparisons were conducted in two groups, divided according to their LDL cholesterol levels (cut point: 156.9 mg/dL).

Results: A total of 2,636 (33.7%) of the 7,832 hypercholesterolemic patients enrolled in MEGA had MetSyn. A 1.9 times higher incidence of CVD was found in the patients with, compared to those without, MetSyn. The risk of CVD in patients with MetSyn was very similar to that in patients with high LDL cholesterol (≥156.9 mg/dL) and with low LDL cholesterol (<156.9 mg/dL). Notably, a 36% significant risk reduction for CVD and 50% risk reduction for total mortality were observed in the patients with MetSyn treated with pravastatin plus diet treatment compared to diet therapy alone. Moreover, the greatest CVD risk reduction was observed in the high LDL-C group with MetSyn compared to those without MetSyn (Hazard ratio 0.44 vs. 0.56, respectively, interaction p=0.07).

Conclusion: Metabolic syndrome increases the risk of CVD regardless of the presence or absence of hypercholesterolemia. Diet plus pravastatin treatment is effective for the prevention of CVD for patients with hypercholesterolemia and MetSyn.
Abstract 2408: Electrophysiologic Monitoring Of Neurological Recovery With Temperature Manipulation After Cardiac Arrest In Rats
Authors: Jia Xiaofeng , Koenig Matthew A , Nickl Robert , Zhen Gehua , Wang Yujie , Hanley Daniel F , Thakor Nitish V , Geocadin Romergryko G
Published: July 2021

Background

Therapeutic hypothermia after cardiac arrest (CA) improves survival and functional outcomes, while hyperthermia is harmful. The optimal tool for tracking the effect of temperature manipulation on recovery of cortical electrical function has not been elucidated. Previously, we demonstrated that good neurological recovery is associated with higher relative electroencephalographic (EEG) entropy, measured by information quantity (IQ).

Methods

We investigated the effect of temperature manipulation on neurological recovery after asphyxial CA in a rodent model using quantitative EEG (qEEG). Twenty-four rats were evenly divided into 3 groups (n=8 per group, randomly assigned), based on 6 hours of hypothermia (T=33°C), normothermia (T=37°C) or hyperthermia (T=39°C) immediately after resuscitation from 7-minute asphyxial CA. Temperature was maintained using surface cooling and warming. Neurological recovery was evaluated using serial Neurological Deficit Score (NDS) calculation.

Results

Greater recovery of IQ was found in rats treated with hypothermia (0.74±0.03), compared to normothermia (0.60±0.03) and hyperthermia (0.56±0.03) (p<0.001). qEEG analysis at different intervals demonstrated a significant separation of IQ scores between the groups only within the first 2 hours of resuscitation (p<0.01). The 72-hour NDS of the hypothermia group (74, 61–74; Median, 25
th
–75
th
percentile) was also significantly improved compared to the normothermia (49, 47– 61) and hyperthermia (43, 0 –50) groups (p<0.001). The IQ values correlated strongly with the 72-hour NDS as early as 30 minutes after resuscitation (Pearson correlation 0.735, 2-tailed significance p=0.01) and maintained a significant association throughout the 72-hour experiment.

Conclusions

Early qEEG was sensitive to the benefit of hypothermia as well as the harmful effect of hyperthermia post-CA and predicted neurological recovery at 72 hours.