bluuebunny/crossref_metadata_2025 huggingface dataset:
TAVI In South Africa's resource-constrained economy: the role of local data in overcoming funding resistance
Authors: Schaafsma E , Scherman J , Weich H , Ntsekhe M
Published: November 2020

The South African (SA) prospective multi-centre observational SHARE-TAVI registry aims to provide local outcomes data on all TAVIs in State & Private sectors, to support local evidence-based policy evaluations, comparing outcomes to international data & identifying local variations.

Methods and results

All 14 implants centres voluntarily capture data into the web-based SHARE-TAVI registry. 1375 patients from Sept 2014-Jan 2020 had pre-TAVI clinical evaluations, 998 proceeded to TAVI & procedural data & complications recorded (VARC-2 criteria), 30d & annual follow up. State sector hospitals provide limited tertiary cardiac care due to severe resource constraints. 13% of TAVIs in SA are in State teaching hospitals, 6.2% of State implants are 2nd generation (2G) devices. In the Private sector the roll-out of TAVI is inhibited by funding resistance, particularly to higher-cost 2G valves. 1st generation (1G) implants comprise 30% of 2019 implants, funding policies leave patients with unaffordable co-payments for 2G valves. Local data (Table 1) shows peri- & 1-year mortality, & procedural success (average 95.4%, & in 2019 98.91%), which are comparable with international data. TAVI in SA is successful despite low volumes & resource limitations. Local data supports superiority of 2G over 1G i.t.o this data and hospital stay length, & unplanned valve-in-valves. No significant differences between 1G & 2G in re-admissions in year 1, but improved quality of life patients experience with TAVI implantation is notable in the NYHA class.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): SA Heart Association registry project funding. Unrestricted educational grants by Medtronic and Edwards Life Sciences
Cost-effective analysis of atorvastatin based on outcome data from a large cohort undergoing PCI before and after the availability of atorvastatin for patients with social health insurance
Authors: Nuehrenberg T , Giesel-Kiefer A , Neumann F.-J , Mossialos E
Published: November 2020

Background

After market introduction of atorvastatin in Germany, the Institute for quality and efficiency in health care (IQWiG) concluded that atorvastatin, as compared to other less potent statins, was not associated with added value and levelled reimbursement to that of other statins. This decision being highly controversial, we hypothesized that a cost-effectiveness analysis based on real-world outcome data may have proven cost-effectiveness of atorvastatin, favouring corresponding reimbursement.

Methods

We investigated the introduction of highly potent statins in a cohort of 10,875 patients undergoing percutaneous coronary intervention (PCI) in a high-volume single centre in Germany between 2010 and 2017 and whether this conferred a clinical benefit as compared to statins with low potency. Routine clinical follow-up was performed at 30 days, 1 and 3 years after intervention with assessment of death, repeat revascularisations and myocardial infarction. Cox proportional hazards regression analyses were performed to adjust for differences in baseline patient characteristics. Based on the outcome data, a cost-effectiveness analysis of atorvastatin was performed, complemented by scenario analyses.

Results

Clinical benefit was present for high potency statins but was limited to all-cause death and not present in rates of myocardial infarction or revascularisations. Regarding cost-effectivenesss, an incremental cost-effectiveness ratio (ICER) of €6,311 / quality-adjusted life year (QUALY) was obtained for atorvastatin in the base case with life time horizon. In scenario analyses, the highest ICERs was €12,216 / QUALY (Figure 1).

Conclusions

We demonstrate that cost-effectiveness analysis can be performed based on routine treatment data. Hence, when there is uncertainty regarding cost-effectiveness analyses based on data from RCTs, timely restricted reimbursement could be a novel way of accumulating such treatment data and serve for evaluation of cost-effectiveness in real-world treatment conditions.

Figure 1

Funding Acknowledgement

Type of funding source: None
Contemporary predictors of readmission outcomes in patients with infective endocarditis: analysis from a national readmission database
Authors: Khayata M , Addoumieh A , Alkharabsheh S , Collier P , Klein A , Griffin B , Xu B
Published: November 2020

Background/Introduction

Infective endocarditis (IE) remains a serious illness that is associated with remarkable morbidity and mortality in the United States (US). There are limited studies that investigated predictors of 30-day readmission risk in this population.

Purpose

We aimed to perform a contemporary analysis to investigate predictors of 30-day readmission in IE patients in the US.

Methods

We used the 2017 national readmission database to identify index admissions among adults (age ≥18) with the diagnosis of IE. Appropriate International Statistical Classification (ICD-10) codes were used to identify patients with IE. Primary outcome of interest was 30-day readmission, and hospital cost was the secondary outcome.

Results

Out of 49,692 admissions for IE, 5,743 (11.6%) patients were readmitted within 30 days. Patients who had 30-day readmission were younger (55±20 vs 61±19 years, P<0.001), 44.8% were females (P=0.08), 27.9% had diabetes mellitus (DM), 56.8% had hypertension, 37.9% had heart failure (HF), 31.3% had chronic kidney disease (CKD), 12.2% had end stage renal disease, and 47.8% had Medicare insurance. Patients who had readmissions within 30 days were more likely to have non-elective index admission (96.9% vs 93.4%, P<0.001), more likely to have hepatitis C (19.5% vs 12.2%, P<0.001), human immunodeficiency virus (HIV) (1.7% vs 1.2%, P<0.001), substance abuse (8.6% vs 5.4%, P<0.001), opioid abuse (24% vs 14.7%, P<0.001), and cocaine use (7.4% vs 4.3%, P<0.001). Overall, 5,393 (10.9%) patients died during index admission. Median cost for readmissions within 30 days was $83,217 [$41,457-$165,487], compared to the index admission cost of $90,257 [$41,945- $208,851] (P<0.001). After adjusting for age, DM, HF, and CKD, substance abuse (odds ratio (OR): 1.19 [1.07–1.33]; P 0.001), opioid abuse (OR: 1.37, [1.26- 1.48]; P<0.001), cocaine use (OR: 1.33 [1.18- 1.48]; P<0.001), HIV (OR: 1.25 [1.01–1.56]; P=0.04), and hepatitis C (OR: 1.34 [1.24–1.45]; P<0.001) correlated with higher odds of readmissions within 30 days (Figure 1).

Conclusion

Approximately 1 in 4 patients admitted for IE in the US had a history of opioid abuse and almost one fifth had hepatitis C. The 30-day readmission rate remains significant in IE with high financial burden on the health system. Both opioid abuse and hepatitis C were among the highest predictors of readmission within 30 days. Identifying modifiable predictors of readmission in this population may reduce readmission risk and healthcare cost.

Figure 1

Funding Acknowledgement

Type of funding source: None
Economic impact of sudden cardiac arrest
Authors: Paratz E , Rowsell L , Ball J , Zentner D , Parsons S , Morgan N , Thompson T , James P , Pflaumer A , Semsarian C , Stub D , Liew D , Smith K , La Gerche A
Published: November 2020

Background

Each year, there are approximately 5,000 out-of-hospital cardiac arrests (OHCAs) in the state of Victoria, Australia (population 6.4 million, state healthcare budget AUD$2.9 billion / €1.8billion). Mortality from OHCA approaches ninety percent. High mortality rates and survivors not returning to work is likely to have an adverse effect on the Victorian economy but this has not been previously investigated.

Purpose

To model the economic impact of OHCA mortality and survivors not returning to work.

Methods

Data on all OHCAs transported by Ambulance Victoria from July 2017- June 2018 in Victoria, Australia was collected, including age, gender, survival to hospital, survival to discharge, and survival to 12 months. Cases were excluded if arrest was precipitated by trauma, exsanguination, overdose, terminal illness, hanging, SIDS, electrocution, sepsis, respiratory causes, drowning, or neurological causes. Pre-arrest employment status of patients was modelled using the Australian Bureau of Statistics Economic Security dataset, which provides contemporary employment rates for gender-matched five-year cohorts for Australians aged 15–79 years. For survivors to 12 months, pre-arrest and post-arrest work status were confirmed. Economic impact was then calculated to a five year horizon utilizing a Markov model with probabilistic sensitivity analysis.

Results

4,934 arrests meeting the inclusion criteria were transported by Ambulance Victoria in twelve months, of whom 4,639 were determined to be cardiac arrests without any exclusion criteria as a precipitant. 695 patients survived to hospital (15.0%), and 325 to discharge (7.0%). At 12 months, 303 patients were alive (6.5% of overall cases, 93.2% of those discharged from hospital). Economic modelling of age and gender-matched data indicated that 1516 patients (35%) would have been employed pre-cardiac arrest, but only 216 survivors (4.7%) would be employed at five years post-arrest. Using Markov modelling incorporating estimated earnings and the pre-determined value of a statistical life, the annual economic burden of cardiac arrest approximated AUD$4 billion (€2.5 billion) at a five-year horizon.

Conclusion

The annual economic impact of cardiac arrest in Victoria, Australia is approximately AUD$4 billion (€2.5 billion) in a five-year horizon. As the annual Victorian state budget for all healthcare is AUD$2.93 billion (€1.8 billion), our data suggests that the economic impact of cardiac arrest is under-appreciated. Therefore, research in this area and providing state-of-the-art care for all cardiac arrest patients should be a healthcare priority.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): NHMRC/NHF Postgraduate Scholarship, RACP JJ Billings Scholarship
Resource utilization and costs associated with achieved LDL-C levels in patients following a myocardial infarction treated with lipid-lowering therapies in Spain
Authors: Escobar Cervantes C , Campos Tapias I , Sorio Vilela F , Lozano J , Kahangire D.A , Sicras-Mainar A
Published: November 2020

Background/Introduction

Reduction in low-density lipoprotein cholesterol (LDL-C) significantly reduces cardiovascular (CV) risk, especially in patients with atherosclerotic CV disease. There is, however, a lack of evidence on the association between achieved LDL-C and resource utilization and costs.

Purpose

Assess the association of achieved LDL-C levels and resource use and costs in patients treated with lipid-lowering therapies (LLT) following a myocardial infarction (MI).

Methods

Retrospective observational study using the BIG-PAC® database, with anonymized electronic medical records from 1.9 million inhabitants from 7 regions in Spain.

Eligible patients were adults (≥18 years), hospitalized for an MI (index date) between January 2015 and December 2017, treated with LLTs (statins and/or ezetimibe) during follow-up (up to 18 months), and with recorded LDL-C values at baseline and follow-up.

Direct (related to health care interventions) and indirect (related to loss of productivity) costs were estimated in 2018€.

Costs incurred during follow-up were computed by achieved LDL-C. Achieved LDL-C was obtained in the year following the MI and at least 2 months after the index date. LDL-C categories were defined as per the 2016 and 2019 ESC/EAS guidelines for dyslipidaemias management: <55 mg/dL, 55–69 mg/dL, 70–99 mg/dL, 100–129 mg/dL and ≥130 mg/dL. Results were adjusted for age, gender, CV disease history and comorbidities.

Results

6025 patients were included. Mean age (SD) was 69.7 (12.2) and 77% were male.

Resource use (not reported in this abstract) and costs monotonically increased with achieved LDL-C. Mean total costs ranged from 5044€ for patients with LDL-C <55 mg/dL to 7567€ for patients with LDL-C ≥130 mg/dL (Table 1).

Only 11% (641/6025) of patients reached recommended LDL-C levels for very-high-risk patients as per 2016 ESC/EAS guidelines (<70 mg/dL), and 1% (68/6025) the LDL-C levels (<55 mg/dL) proposed in the 2019 guidelines.

Conclusions

Achieving lower LDL-C levels following an MI may be associated to lower resource use and costs. Many patients do not achieve recommended LDL-C levels despite treatment with LLT. These data suggest that use of more intense LLT, with a greater reduction in LDL-C, would be beneficial from a clinical and economic perspective.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Amgen (Europe) GmbH
Measuring the systolic and the diastolic properties of single human pluripotent stem-cell cardiomyocyte for drug testing and disease modeling
Authors: Ballan N , Shaheen N , Keller G , Gepstein L
Published: November 2020

Background

The advent of human pluripotent stem cell–derived cardiomyocytes (hPSC-CMs) provided exciting tools for cardiovascular physiological studies, disease modeling and drug testing applications. Current platforms for studying the mechanical properties of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) as single-cells do not measure forces directly, require numerous assumptions, and cannot study cell mechanics at different loading conditions.

Objective

To establish a novel platform to assess the active and passive mechanical properties of single-cell hPSC-CMs at different loading conditions and to demonstrate the potential of this approach for drug testing and disease modeling applications.

Methods and results

To allow morphological maturation, hPSC-CMs were treated with Tri-iodo-thyronine hormone, dexamethasone and Insulin-like growth factor-1. The hPSC-CM were then lifted and attached to a highly sensitive optical-force transducer and a piezoelectric length controller and electrically-stimulated. The attached hPSC-CM remained intact and contractile allowing evaluation of their passive and active mechanical properties. Utilizing this technique, single-cell hPSC-CMs exhibited positive length-tension (Frank-Starling) relationships, and appropriate inotropic, klinotropic, and lusitropic changes in response to treatment with isoproterenol. The unique potential of the approach for drug testing and disease modeling was exemplified by treating the cells with doxorubicin (a potential cardiotoxic anti-cancer agent) and omecamtiv mecarbil (a positive ionotropic drug currently in stage 3 clinical trial). The results of these studies recapitulated the drugs' known actions to suppress (doxorubicin) and augment (omecamtiv mecarbil at low dose) cardiomyocyte contractility. Finally, novel insights were gained regarding the cellular effects of these drugs as doxorubicin treatment led to cellular mechanical alternans and high doses of omecamtiv mecarbil suppressed contractility and worsened the cellular diastolic properties.

Conclusion

A novel method that allows direct active and passive force measurements from single hPSC-CMs at different loading conditions for the first time was established and validated. Our results highlight the potential implications of this novel approach for pharmacological studies and disease modeling studies.

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): European Research Council
Role of CACNA1C variants in Brugada syndrome: clinical aspects and genetic testing strategies
Authors: Novelli V , Memmi M , Malovini A , Mazzanti A , Liu N , Yanfei R , Bongianino R , Monteforte N , Bloise R , Morini M , Napolitano C , Priori S.G
Published: November 2020

Background

Inconsistent data support the role of CACNA1C as a disease-causing gene responsible for Brugada syndrome (BrS). As of today, the only gene consistently linked with BrS is SCN5A. Several CACNA1c genetic variants have been reported in association wirh BrS; however, due to the limited evidence, CACNA1C is not suggested for routine genetic screening for BrS.

Purpose

In this study, we carried out a systematic screening of CACNA1C gene, including a functional evaluation of the identified variants, in order to determine the yield of screening in a large series of BrS probands and to address the hypothesis that an appropriate clinical selection of patients would substantially improve the yield of genetic testing.

Methods and results

Overall 564 consecutive patients, referred for BrS genetic testing, were sequenced for CACNA1C gene. Patients were divided in two groups: discovery cohort (n=200 patients) and confirmation cohort (n=363 patients). Furthermore, analysis of the clinical phenotypes of a matched SCN5A positive BrS cohort (n=146) was included for phenotype characterization.

In the discovery cohort we identified 11 different genetic variants of whom 2 (18%) were considered as potentially causative based on ACMG guidelines. However, a large proportion (81%) was classified as variants of unknown significance (VUS). Functional evaluation of the identified variants, including pathogenic and VUS, was assessed by patch-clamp and immunofluorescence studies. Re-evaluation of the variants, including functional studies results, indicated an increase of pathogenic or likely pathogenic variants (81%) getting a yield of screening of 5% in the discovery cohort. Results from the confirmation cohort confirmed a low rate of CACNA1C carriers with a yield of screening of 2.2%.

Analysing the clinical phenotype of all CACNA1C carriers showed a significantly shorter QTc [371 ms ± 16 ms vs. 399±18 ms; p=0.000004]. Furthermore, the prevalence of CACNA1C variants was highest (12.9%) among patients with a QTc in the lowest quartile (QTc <390 ms). ROC curve showed an AUC of 0.91 for QTc a cut-off of 385 ms, suggesting a high predictive accuracy.

Conclusion

We confirmed that CACNA1C variants are not a common cause of BrS, with a yield of screening of 2–5%. However, pathogenic variants are more frequent (12.5%) in patients with a shorter QTc, suggesting a genetic testing strategy in this subgroup of BrS patients. Furthermore, our data highlights the impact of robust functional studies to improve variant classification and reduce uncertainties.

Funding Acknowledgement

Type of funding source: None
Rare variants in HCN4 identified in the general population are associated with complete atrioventricular (AV) block, 1. degree AV block and bundle branch block, results from 50.000 exomes
Authors: Jensen J , Vad O.B , Paludan-Muller C , Lundegaard P.R , Svendsen J.H , Haunsoe S , Bundgaard H , Olesen M.S
Published: November 2020

Background/Introduction

Cardiac conduction disorders cover disorders such as atrioventricular (AV) block and bundle branch block. Genome-wide association studies have identified more than 100 genetic loci for atrial fibrillation, including HCN4 loci associated with duration of the PR interval, a proxy for AV dysfunction. Recent candidate studies suggest an association between HCN4 variants and AV-block.

Purpose

We seek to determine the contribution of rare genetic variants in HCN4 to complete AV-block, 1. degree AV-block and bundle branch block (BBB) in the general population.

Methods

The UK Biobank is a population-based study of 500 000 individuals including a subset with genome-wide genotyping and exome sequencing (n=45,596). In this case-control study, we included persons of genetically determined white-European ancestry and analyzed their exome data. Analyses were performed using a logistic mixed-effects model. A gene-based burden analysis and single variant test were performed to examine the relationship between HCN4 variants and complete AV-block, 1. degree AV-block and BBB in the general population.

Results

The study included 43,371 persons. In an analysis of the HCN4 genes a significant association between rare variants (MAF<0.01) in HCN4 gene was found (complete AV-block, P=2.5x10–5, 1. degree AV-block, P=1.3x10–3 and BBB, P=0.01) (Figure 1A). The association to complete AV block was mostly driven by the variants Ser835Phe (P=2.7e-3), Glu153Gly (P=3.5e-3) and Arg378Cys (P=6.3e-3) (Figure 1B).

Conclusions

Rare HCN4 variants contribute to the risk of complete AV-block, 1. degree AV-block and BBB in the general population. These HCN4 variants seem to confer a substantial penetrance. Clinical screening for some of these variants seems appropriate.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Hallas Møller - Novo nordisk
Neuropeptides as novel regulators of human atrial TASK-1 currents
Authors: Wiedmann F , Nietfeld J , Kraft M , Ratte A , Benda S , Katus H.A , Schmidt C
Published: November 2020

Background/Introduction

The neurokinin-III receptor (NK3R) was recently shown to regulate action potential duration (APD) in atrial cardiomyocytes by inhibition of a background potassium current. In the human heart, TASK-1 (hK2P3.1) two-pore-domain potassium channels display atrial-specific expression. Because of their phospholipase C (PLC)-dependent regulation, TASK-1 channels are a promising candidate to mediate APD prolongation via the Gq-coupled neurokinin-III receptor.

Purpose

To investigate whether TASK-1 channels mediate neurokinin-III receptor activation induced APD prolongation and to dissect the underlying molecular mechanisms.

Methods

Patch clamp measurements were performed in atrial cardiomyocytes isolated from patients with atrial fibrillation. Xenopus laevis oocytes heterologously expressing hTASK-1 and hNK3R were subjected to two-electrode voltage-clamp recordings.

Results

In Xenopus oocytes heterologously overexpressing hNK3R and hTASK-1 administration of substance P or neurokinin B resulted in TASK-1 current inhibition. This could be reproduced by application of the high affinity neurokinin-III receptor agonist senktide. Moreover, preincubation with the neurokinin-III receptor antagonist osanetant blunted the effect of senktide. Pharmacological experiments and mutagenesis studies could show a protein kinase C (PKC)-independent mechanism of TASK-1 current inhibition: upon NK3R activation TASK-1 channels are blocked via Gq-mediated PLC activation, in a DAG-dependent fashion. Finally, effects of senktide on atrial background currents could be reproduced in human atrial cardiomyocytes isolated from patients with atrial fibrillation.

Conclusion

Neurokinin-III receptor stimulation suppresses background potassium currents in isolated human atrial cardiomyocytes from patients with atrial fibrillation. Heterologously expressed human TASK-1 channels are inhibited by neurokinin-III receptor activation in a PLC and DAG dependent fashion, suggesting neuropeptides as novel regulators of human atrial TASK-1 currents.

Central Illustration

Funding Acknowledgement

Type of funding source: None
Noninvasive assessment of dynamic cardiac electrophysiology in normal human subjects
Authors: Stoks J , Van Rees B.D , Nguyen U.C , Peeters R.L.M , Dendale P , Cluitmans M.J.M , Volders P.G.A
Published: November 2020

Introduction

Electrocardiographic imaging (ECGI) has been used to investigate arrhythmia mechanisms in various conditions. Data on normal human subjects, especially in Europe, are scarce. Dynamic characteristics of ventricular activation and recovery during sinus rhythm have not been assessed before.

Purpose

To examine cardiac electrophysiology and its dynamic aspects in normal subjects using ECGI, in order to provide a range of normal patterns and values for activation (AT) and recovery times (RT), activation-recovery intervals (ARI, a surrogate for action potential duration) and their dynamicity.

Methods

11 Subjects (age 57±7 years, 27% male, all normal LVEF) with atypical chest pain who underwent a cardiac CT-scan as part of clinical care but who were negative for any pathology on full examination were included. A validated non-commercial potential-based formulation of ECGI was used to reconstruct unipolar electrograms (EGMs) on the epicardial surface for three sinus beats within minutes from each other, per individual. ATs and RTs were determined as the maximum negative upslope during QRS, and maximum positive upslope during T wave of the local EGMs. Additionally, we determined locations of first and last activation and recovery. Inter- and intra-individual differences were computed.

Results

Subjects had normal 12-lead characteristics without ST-deviations, and an average QTc interval of 415±18ms. Figure 1, panel A shows ECGI during sinus rhythm for 3 representative subjects, and panel B summarizes all findings on the entire epicardium. The first epicardial activation breakthrough typically occurred on the right ventricle (RV), consistent with the concept that the thinner RV wall accounts for a faster transmural activation. Last activation was mostly on the base of the left ventricle (LV), on the inferior to lateral wall. Earliest recovery occurred predominantly on the anterior surface, while latest recovery occurred on the inferior surface. Complete activation of the epicardial surface (from earliest to latest AT) took 41±8ms, while recovery (earliest AT to latest RT) took 317±24ms and average ARI (local AT to local RT) took 232±23ms. Thus, inter-individual variation of recovery duration was higher than of activation. Intra-individual differences between beats in ATs, RTs and ARIs of distinct sinus beats were small (2.3±3.1ms, 9.7±8.8ms and 9.8±9.1ms, respectively) suggesting that ECGI enables stable reconstruction quality (Figure 1, panel C).

Conclusion

In this cohort, noninvasive ECGI provides novel insights in ventricular electrophysiology. Electrical recovery is more variable than activation, both intra-individually and inter-individually. Overall, AT, RT and ARI differences between sinus beats were low. ECGI appears suitable to assess dynamic electrical patterns during cardiac pathology.

Figure 1

Funding Acknowledgement

Type of funding source: None
The effect of oestrogen withdrawal on cardiac Ca2+ regulation and the influence of GPER1
Authors: Francis A.J , Firth J.M , Islam N , Gorelik J , MacLeod K.T
Published: November 2020

Background

Post-menopausal women have an enhanced risk of developing heart failure, attributed to declining oestrogen levels during menopause. However, the signalling mechanisms remain undetermined.

Purpose

We aim to determine the role of G-protein coupled oestrogenic receptor 1 (GPER1) in intracellular Ca2+ regulation and the consequences of hormonal changes that may exacerbate the pathophysiology of heart failure.

Methods

Ovariectomy (OVx) (mimics menopausal hormone changes) or sham surgeries were conducted on female guinea pigs. Left ventricular cardiomyocytes were isolated 150-days post-operatively for experimental use. Cellular t-tubule network and structural integrity was measured using fluorescent di-8-ANEPPs staining and scanning ion conductance microscopy. GPER1 expression and localisation was measured by Western blot and immunostaining. The role of GPER1 activation was measured using selective agonist G-1 in electrophysiological and Ca2+-sensitive dye fluorescence experiments.

Results

Following oestrogen withdrawal, the t-tubule network density decreased by 13% and z-groove index reduced by 15%. GPER1 predominantly localised to the peri-nuclear endoplasmic reticulum and its expression increased by 32% in OVx. Action potential duration (APD) prolonged in OVx and following GPER1 activation, APD90 shortened by 11% and 25% in sham and OVx respectively. OVx cells had larger peak inward Ca2+ current (ICaL) (by 22%) and sarcoplasmic reticulum (SR) Ca2+ content (by 13%), compared with sham. While GPER1 activation had little effect on peak ICaL or SR content, it reduced Ca2+ transient amplitude (by 20%), SR fractional release (by 11%) in OVx cells. The frequency of occurrence of spontaneous Ca2+ waves evoked by periods of rapid stimulation reduced by 40% and wave-free survival time prolonged in OVx cells following GPER1 activation.

Conclusions

In the hearts of an animal species whose electrophysiology and intracellular Ca2+ regulation is akin to humans, we show that following oestrogen deficiency, the t-tubule network is down-regulated and becomes disorganised, GPER1 expression is increased and its activation induces negative inotropic responses in cardiomyocytes. This may limit the adverse changes to Ca2+ signalling reported in OVx that could be pro-arrhythmic and exacerbate the progression to heart failure.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): British Heart Foundation
Cardiac mitofusin-1 is declined in non-responding patients with idiopathic dilated cardiomyopathy
Authors: Hsiao Y , Shimizu I , Wakasugi T , Jiao S , Watanabe T , Kashimura T , Yoshida Y , Hanawa H , Ozaki K , Minamino T
Published: November 2020

Background/Introduction

Mitochondria are dynamic regulators of cellular metabolism and homeostasis. The dysfunction of mitochondria has long been considered a major contributor to aging and age-related diseases. The prognosis of severe heart failure is still unacceptably poor and it is urgent to establish new therapies for this critical condition. Some patients with heart failure do not respond to established multidisciplinary treatment and they are classified as “non-responders”. The outcome is especially poor for non-responders, and underlying mechanisms are largely unknown.

Purpose

Studies indicate mitochondrial dysfunction has causal roles for metabolic remodeling in the failing heart, but underlying mechanisms remain to be explored. This study tried to elucidate the role of Mitofusin-1 in a failing heart.

Methods

We examined twenty-two heart failure patients who underwent endomyocardial biopsy of intraventricular septum. Patients were classified as non-responders when their left-ventricular (LV) ejection fraction did not show more than 10% improvement at remote phase after biopsy. Fourteen patients were classified as responders, and eight as non-responders. Electron microscopy, quantitative PCR, and immunofluorescence studies were performed to explore the biological processes or molecules involved in failure to respond. In addition to studies with cardiac tissue specific knockout mice, we also conducted functional in-vitro studies with neonatal rat ventricular myocytes.

Results

Twenty-two patients with IDCM who underwent endomyocardial biopsy were enrolled in this study, including 14 responders and 8 non-responders. Transmission electron microscopy (EM) showed a significant reduction in mitochondrial size in cardiomyocytes of non-responders compared to responders. Quantitative PCR revealed that transcript of mitochondrial fusion protein, Mitofusin-1, was significantly reduced in non-responders. Studies with neonatal rat ventricular myocytes (NRVMs) indicated that the beta-1 adrenergic receptor-mediated signaling pathway negatively regulates Mitofusin-1 expression. Suppression of Mitofusin-1 resulted in a significant reduction in mitochondrial respiration of NRVMs. We generated left ventricular pressure overload model with thoracic aortic constriction (TAC) in cardiac specific Mitofusin-1 knockout model (c-Mfn1 KO). Systolic function was reduced in c-Mfn1 KO mice, and EM study showed an increase in dysfunctional mitochondria in the KO group subjected to TAC.

Conclusions

Mitofusin-1 becomes a biomarker for non-responders with heart failure. In addition, our results suggest that therapies targeting mitochondrial dynamics and homeostasis would become next generation therapy for severe heart failure patients.

Funding Acknowledgement

Type of funding source: None
High aerobic exercise capacity predicts increased mitochondrial response to exercise training
Authors: Schwarzer M , Zeeb S , Heyne E , Koch L.G , Britton S.L , Doenst T
Published: November 2020

Low exercise capacity is a strong predictor of all-cause cardiovascular mortality and morbidity. In contrast, high exercise capacity is protective and “physical fitness” is considered beneficial. These effects seem to be mediated through mitochondrial function. Importantly, exercise capacity consists of an intrinsic (genetic) and an extrinsic (exercise, environmental) part. In humans, these two parts cannot be truly separated. The rat model of high (HCR) and low (LCR) capacity runners allows to distinguish between the two parts. We assessed mitochondrial function in this model, specifically investigating the impact of exercise training on mitochondrial respiratory capacity.

HCR and LCR were divided into control and exercised groups. Exercise capacity was determined individually using a ramped test. Animals were trained five times a week for four weeks on a treadmill. Mitochondria were isolated from heart, M. gastrocnemius and liver. Citrate synthase activity and protein content were determined photometrically and respiratory capacity was measured using a Clark-type electrode.

At the same age and tibia length, LCR-C were heavier and had a lower heart to body weight ratio than HCR-C. Citrate synthase activity was lower in skeletal muscle of LCR but cardiac citrate synthase was not different between sedentary HCR and LCR. Respiratory capacity in heart and liver was not different between sedentary HCR and LCR but was lower in skeletal muscle in LCR compared to HCR with all selected substrates (glutamate: 86,0±17,6 vs. 63,7±8,0; succinate: 203±19 vs. 136±17 nAO/min/mg Protein). Exercise training led to an increase in body weight in HCR but did not change body weight in LCR. Similarly, gastrocnemius and soleus weights only increased with exercise in HCR. Exercise led to an increase in citrate synthase activity in hearts of HCR (0,78±0,07 vs. 1,58±0,45 U/mg Protein) but not of LCR. Consistently, mitochondrial respiratory capacity was found increased in HCR with exercise in heart with all substrates (glutamate: 261±43 vs. 305±35; succinate 417±32 vs. 539±65 nAO/min/mg Protein). Liver was not affected by exercise.

Conclusion

Our data suggest that genetic predisposition for aerobic capacity additionally affects the response of mitochondria to exercise. Thus, it may be possible that the “born runner” benefits more from aerobic exercise training than the “less genetically equipped counterpart”.

Funding Acknowledgement

Type of funding source: None
Cardioprotection by remote ischemic conditioning is transferable by plasma and mediated by exosomes
Authors: Lassen T.R , Just J , Hjortbak M.V , Jespersen N.R , Stenz K.T , Gu T , Yan Y , Su J , Nyengaard J.R , Kristiansen S.B , Drasbek K.R , Kjems J , Botker H.E
Published: November 2020

Background

Remote ischemic conditioning (RIC) by brief periods of limb ischemia and reperfusion protects against ischemia-reperfusion injury. However, the mechanism is unknown.

Purpose

We studied the role of exosomes for mediating the cardioprotective signal and whether they accumulate in injured myocardium.

Methods

Blood samples from 12 healthy male volunteers were obtained prior to and one hour after RIC. Plasma obtained before and after RIC (n=4) (P-Pre and P-Post) was used to evaluate the transferability of RIC. Pre- and Post-RIC plasma (n=8) was separated into an exosome rich fraction (Exo-Pre and Exo-Post) and an exosome depleted fraction (Prot-Pre and Prot-Post) by size exclusion chromatography. All studies were carried out in duplicate samples from each volunteer. Infarct size was compared in Sprague-Dawley rat hearts perfused with plasma, exosomes and exosome depleted fractions in a Langendorff model. We investigated changes in the miRNA content of the exosomes after RIC by a human miRNA panel. Additionally, fluorescently labeled exosomes isolated from C2C12 cells were used to assess accumulation in injured myocardium in an in vivo rat model. Rats were divided into an infarct group (n=6) (left anterior descending artery ligation) and a sham group (n=6) (without ligation). Labelled exosomes were injected in the femoral vein prior to reperfusion. Exosome-accumulation in infarcted or sham myocardium was evaluated.

Results

P-Post reduced infarct size by 15% points compared with P-Pre (55±4% vs 70±6%, p=0.03) (Fig. 1a). Exo-Post reduced infarct size by 16% points compared with Exo-Pre (53±15% vs 68±12%, p=0.03) (Fig. 1b). Prot-Post did not affect infarct size compared to Prot-Pre (64±3% and 68±10%, p>0.99). We found miRNA-16, miRNA-144 and miRNA-451 to be upregulated in exosomes after RIC and the mTOR-pathway as a potential target for these miRNAs. In the in vivo model, labelled exosomes accumulated more intensively in the infarct area than in remote areas and sham hearts (Fig. 1c).

Conclusion

Cardioprotection by RIC is mediated by exosomes with a changed miRNA profile and exosomes accumulate in injured myocardium.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Novo synergy
Acute dietary saturated fat intake suppresses human monocyte subset inflammatory and chemokine responses
Authors: Rahman M.S , Haskard D.O , Frost G , Vorkas P , Woollard K.J
Published: November 2020

Background

Dietary saturated fat (SF) intake is implicated in increasing cardiovascular risk. Studies suggest SF may incite an inflammatory immune response yet the mechanisms for this remain unclear. Circulating blood monocyte subsets (classical “CD16low” and non-classical/intermediate “CD16high”) are thought to differentially contribute to the macrophage foam cell burden in atherosclerotic plaque, yet they are heterogenous and much is still unknown about their response to dietary lipid.

Purpose

This dietary intervention study hypothesised that a subset-specific monocyte response occurs following acute SF intake in healthy individuals.Top of Form

Methods

10 healthy participants were fed a coconut oil, lauric acid-rich meal. Monocyte subsets were purified from fasting and 4h postprandial blood by fluorescence activated cytometry (FACS) into CD16low and CD16high subsets. Surface marker expression was recorded by FACS, gene expression by qPCR, lipid loading by fluorescence microscopy, cytokine responses by ELISA and mass spectrometry was utilised to trace dietary fat into circulating monocytes. Triglyceride rich lipoprotein (TGRL) was obtained through ultracentrifugation of postprandial blood. TLR agonists LPS (TLR4) and R848 (TLR7/8) were used to replicate infectious stimuli to provoke a cytokine response.

Results

SF meal intake resulted in a 4h postprandial rise in serum triglycerides (TG). Other than a small rise in HLA-DR in postprandial CD16low monocytes, no changes in CD14, CD16 or CD11c levels were noted. Inflammatory gene expression was downregulated although a rise in lipid handling gene ABCA1 was noted in both subsets. Postprandial monocytes accumulated cytoplasmic neutral lipid droplets (larger and more numerate droplets in CD16low). Mass-spectrometry confirmed entry of dietary lipid into circulating monocytes. Postprandial monocyte functional responses were impaired; lipid-loaded postprandial monocytes were less able to migrate towards a chemokine gradient. Following TLR challenge, the inflammatory response was abrogated in postprandial monocytes, further suppressed by in vitro postprandial TGRL addition. Lipidomic analyses confirmed postprandial monocyte lauric acid accumulation in the form of free fatty acid and TG trilaurin, and 9(S)-, 13(S)-HODE and 17(S)-HDoHE, that are metabolites of docosahexanoic acid (DHA) and possess anti-inflammatory properties. The attached graphical abstract summarises the pertinent findings.

Conclusions

Acute dietary SF intake of a lauric acid-rich meal results in postprandial monocyte suppression of inflammatory TLR responses, a reduction in the ability to migrate towards a chemokine gradient whilst accumulating cytoplasmic neutral lipid droplets. The immunosuppression may be caused by accumulation of anti-inflammatory metabolites of DHA.

Graphical Abstract

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): British Heart Foundation, UK
m6A methyltransferase RBM15 promotes cardiomyocytes survival under hypoxia by increasing Thbs4 RNA methylation and mediating PI3K/Akt signaling
Authors: Cheng H , Song X.Y , Xue J.Q , Chen L , Xu R.D , Qian J.Y , Zou Y.Z , Ma J.Y , Ge J.B
Published: November 2020

Background

mRNA modifications constitute ancient mechanisms in regulating gene expression after transcription. N6-methyladenosis (m6A), which is the most prevalent internal RNA modification, is not only installed by m6A methyltransferases, removed by demethylases, but also specifically bounded by RNA-binding proteins. As a significant component in the m6A methyltransferase complex, RNA binding motif protein 15 (RBM15) plays a vital role in m6A methylation. Nevertheless, its function and mechanism in myocardial infarction (MI) remain poorly defined.

Purpose

To investigate the role and mechanism of RBM15 in regulating its targets through m6A methylation in MI. The research results will not only add new content to the basic mechanism of myocardial protection but also provide new ideas and new targets for the prevention and treatment of MI.

Methods

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to clarify the total m6A level, and Reverse transcription quantitative real-time PCR (RT-qPCR) and Western blot were used to determine the expression of RBM15 in normal and MI tissues. Then the effects of RBM15 on cardiomyocytes were clarified using apoptosis assay, and cell proliferation assay. Methylated RNA immunoprecipitation sequencing (MeRIP-seq), and transcriptomic RNA sequencing (RNA-seq) were used to perform the regulator mechanism of RBM15 on target gene Thbs4 in MI.

Results

In this research, we showed that total m6A methylation was increased in MI, and RBM15 was a main factor involved with this process. Silencing RBM15 remarkably decreased cell proliferation and increased apoptosis in vitro, and resulted in severe cardiac remodeling and further exacerbation of cardiac dysfunction in vivo, whereas its overexpression caused the opposite effects. Then, Thbs4 was identified as a direct downstream target of RBM15, and RBM15 induced m6A methylation on the 3'UTR of Thbs4 pre-mRNA. We also found that it showed faster Thbs4 mRNA decay and exhibited decreased mRNAs and levels of protein expression in RBM15-deficient cardiomyocytes under hypoxia. Furthermore, we confirmed that RBM15 contributed significantly to regulate the PI3k/Akt pathway.

Conclusions

Our work uncovers a complex RBM15-Thbs4-PI3K/Akt regulatory model based on m6A methylation and provides a new insight into the epi-transcriptomic dysregulation in MI development.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Natural Science Foundation of China
A meta-analysis of the transcriptional landscape of end stage heart failure with reduced ejection fraction
Authors: Lanzer J , Ramirez-Flores R , Schultz J.H , Levinson R , Saez-Rodriguez J
Published: November 2020

During heart failure (HF) the myocardium undergoes ventricular remodeling, which is accompanied by changes in gene expression. Transcriptomic studies have contributed to fundamental knowledge of this remodeling. However many studies do not agree on the differentially expressed marker genes. We hypothesized that a comprehensive meta-analysis of available studies would help to address this incongruence.

We curated and uniformly processed 14 public transcriptomic data sets consisting of left ventricular samples from 265 healthy and 642 failing hearts. We assessed their comparability by applying transfer learning based classifiers. We then combined all datasets to extract a consensus gene signature. Combining this consensus signature with biological prior knowledge, we estimated transcription factor activities with DoRothEA and pathway activities by footprint analysis with PROGENy.

Although single studies reported highly dissimilar marker genes, transfer knowledge based approaches revealed that disease patterns are conserved across studies. We derived a gene ranking that reflects consistent molecular hallmarks of HF. The ranking is strongly enriched in fibrosis related gene sets and contains significant (all p-values <0.05) footprints of numerous transcription factors including Nanog, Sox2, Pbx3, Mef2; pathways including Jak-Stat and miRNAs including MIR-206, MIR-514.

We demonstrated the feasibility of combining transcriptional studies from different technologies, years and centers. We extracted a consensus gene signature as a valuable resource to understand common molecular patterns in HF. To our knowledge, this report represents the largest meta-analysis of transcriptional HF studies to date.

Selected transcription factor (TF) activities derived via footprint analysis from the consensus gene ranking TF NES Size P-value SOX2 6.3 179 2.59E-10 MYNN −5.7 347 8.14E-09 MTA2 −5.3 29 9.1E-08 ZBTB7A 4.8 66 1.25E-06 BL3 −4.5 26 5.46E-06 ZEB2 −3.9 46 8.99E-05 NANOG 3.81 34 0.00047 PBX3 3.4 41 0.0005 MEF2C 3.1 55 0.001602 MEIS2 2.7 718369 0.00656 NES, normalized enrichment score; size, regulon size.

Graphical summary

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Klaus Tschirer Stiftung
Abnormal P-waves found in patients with sleep-disordered breathing are associated with triggered pro-arrhythmic activity
Authors: Lebek S , Wester M , Tafelmeier M , Fisser C , Hirt S , Schopka S , Schmid C , Maier L.S , Arzt M , Wagner S
Published: November 2020

Background

Sleep-disordered breathing (SDB) is frequently associated with atrial arrhythmias, but diagnostic markers that predict the propensity for atrial arrhythmias are missing. Abnormal P-wave terminal force in lead V1 (PTFV1) has been associated with atrial structural/electrical remodeling and arrhythmias.

Purpose

Here we investigate the association of triggered pro-arrhythmic activity with abnormal PTFV1 in human right atrial appendage biopsies of patients without and with SDB.

Methods

30 patients undergoing elective coronary artery bypass grafting were screened for SDB by polygraphy. An apnoea-hypopnea index (AHI) of ≥15/h defined SDB. PTFV1 was measured as product of negative P-wave amplitude and duration in lead V1 and was defined as abnormal if >4000 ms*μV. Ca/Calmodulin-dependent protein kinase II (CaMKII) activity was measured in human right atrial appendage biopsies by a specific HDAC4 pull-down assay. Premature atrial contractions (PACs) were triggered by exposure to 100 nM isoproterenol (at 3.5 mM [Ca]o) in human atrial trabeculae. PACs severity was classified by a score from 0 points (no arrhythmias) to 5 points (salve). In addition, atrial fibrosis was quantified by Masson's trichrome stain in cryo-sectioned atrial tissue. Multivariate linear regression analyses were performed accounting for age, sex, BMI, existing AF, heart failure, diabetes, and creatinine.

Results

Interestingly, the AHI was independently associated with the magnitude of PTFV1 (fig. A+B, B=57.47±21.03, R2=0.48, P=0.01). Importantly, patients with an abnormal PTFV1 had a significantly increased CaMKII activity (fig. C, P=0.04) and showed significantly more severe triggered PACs (fig. D, P=0.02). Moreover, the magnitude of PTFV1 correlated significantly and independently with PAC severity (fig. D, B=0.0005±0.0002, R2=0.50, P=0.03). Consistently, these arrhythmias could be significantly reduced by acute CaMKII inhibition (5 μM KN93, P<0.01), which abolished the correlation between PTFV1 and PAC severity (P=N.S.). Surprisingly, atrial fibrosis was significantly decreased in patients with an abnormal PTFV1 (fig. E, P=0.02), suggesting that abnormal PTFV1 is a marker of proarrhythmic atrial electrical remodeling of functional cardiomyocytes but not of fibrotic tissue.

Conclusion

The severity of sleep-disordered breathing (AHI) is independently associated with an abnormal PTFV1. Intriguingly, this abnormality is associated with an increased CaMKII activity and with CaMKII-dependent arrhythmias, suggesting PTFV1 to be a potential tool to evaluate the pro-arrhythmic risk of patients with SDB.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Part of this study was funded by Philips Respironics.