The thrombin receptor PAR4 supports visceral adipose tissue inflammation.

Thrombin inhibition suppresses adiposity, WAT inflammation and metabolic dysfunction in mice. Protease-activated receptor (PAR)1 does not account for thrombin-driven obesity, so we explored the culprit role of PAR4 in this context. Male WT and PAR-4-/- mice received a high fat diet (HFD) for 8 weeks, WT controls received standard chow. Body fat was quantified by NMR. Epididymal WAT was assessed by histology, immunohistochemistry, qPCR and lipase activity assay. 3T3-L1 preadipocytes were differentiated ± thrombin, acutely stimulated ± PAR4 activating peptide (AP) and assessed by immunoblot, qPCR and U937 monocyte adhesion. Epicardial adipose tissue (EAT) from obese and lean patients was assessed by immunoblot. PAR4 was upregulated in mouse WAT under HFD. PAR4-/- mice developed less visceral adiposity and glucose intolerance under HFD, featuring smaller adipocytes, fewer macrophages and lower expression of adipogenic (leptin, PPARγ) and pro-inflammatory genes (CCL2, IL-1ß) in WAT. HFD-modified activity and expression of lipases or perilipin were unaffected by PAR4 deletion. 3T3-L1 adipocytes differentiated with thrombin retained Ki67 expression, further upregulated IL-1ß and CCL2 and were more adhesive for monocytes. In mature adipocytes, PAR4-AP increased phosphorylated ERK1/2 and AKT, upregulated Ki67, CCl2, IL-ß and hyaluronan synthase 1 but not TNF-α mRNA, and augmented hyaluronidase-sensitive monocyte adhesion. Obese human EAT expressed more PAR4, CD68 and CD54 than lean EAT. PAR4 upregulated in obesity supports adipocyte hypertrophy, WAT expansion and thrombo-inflammation. The emerging PAR4 antagonists provide a therapeutic perspective in this context beyond their canonical antiplatelet action.

The role of cellular senescence in profibrillatory atrial remodeling associated with cardiac pathology.

AIMS: Cellular senescence is a stress-related or aging response believed to contribute to many cardiac conditions; however, its role in atrial fibrillation (AF) is unknown. Age is the single most important determinant of the risk of AF. The present study was designed to: 1) Evaluate AF-susceptibility and senescence-marker expression in rat models of aging and myocardial infarction (MI); 2) Study the effect of reducing senescent-cell burden with senolytic therapy on the atrial substrate in MI-rats; 3) Assess senescence markers in human atrial tissue as a function of age and the presence of AF. METHODS AND RESULTS: AF-susceptibility was studied with programmed electrical stimulation. Gene and protein expression was evaluated by immunoblot or immunofluorescence (protein) and digital-PCR or RT-qPCR (mRNA). A previously-validated senolytic combination, dasatinib and quercetin (D + Q), (or corresponding vehicle) was administered from the time of sham or MI surgery through 28 days later. Experiments were performed blinded to treatment-assignment. Burst pacing-induced AF was seen in 100% of aged rats, 87.5% of young MI-rats and 10% of young-control rats (P≤0.001 vs. each). Conduction velocity was slower in aged (both left atrium, LA and right atrium, RA) and young-MI (LA) rats versus young-control rats (P≤0.001 vs. each). Atrial fibrosis was greater in aged (LA and RA) and young-MI (LA) versus young-control rats (P < 0.05 for each). Senolytic therapy reduced AF-inducibility in MI-rats (from 8/9 rats, 89% in MI-vehicle, to 0/9 rats, 0% in MI-D + Q, P < 0.001) and attenuated LA-fibrosis. Double staining suggested that D + Q acts by clearing senescent myofibroblasts and endothelial cells. In human atria, senescence-markers were upregulated in older (≥ 70 years) and longstanding-AF patients versus individuals ≤ 60 and sinus-rhythm controls respectively. CONCLUSIONS: Our results point to a potentially significant role of cellular senescence in AF pathophysiology. Modulating cell senescence might provide a basis for novel therapeutic approaches to AF.

Treatment of Staphylococcus aureus infection with sphingosine in ex vivo perfused and ventilated lungs.

BACKGROUND: Ex vivo lung perfusion (EVLP) has expanded the donor pool for lung transplantation. Pulmonary Staphylococcus aureus infection, especially that caused by multidrug-resistant strains, is a severe threat to posttransplantation outcomes. Sphingosine is a lipid compound that exhibits broad-spectrum antibacterial activity. Therefore, we aimed to evaluate the effects of S aureus infection on EVLP and whether sphingosine administration during EVLP prevents infection with S aureus. METHODS: Eighteen pigs were randomly assigned to 3 groups: uninfected, infected with S aureus with NaCl treatment, or infected with sphingosine treatment. Bacterial numbers were determined before and after treatment. Sphingosine concentrations in the lung tissues were determined using biochemical assays. Lung histology, lung physiological parameters, perfusate content, lung weight, and cell death were measured to analyze the effects of infection and sphingosine administration on EVLP. RESULTS: Sphingosine administration significantly reduced the bacterial load. The concentration of sphingosine in the bronchial epithelium was elevated after sphingosine administration. S aureus infection increased pulmonary artery pressure and pulmonary vascular resistance. Lung edema, histology scores, lactate and lactate dehydrogenase levels in the perfusate, ΔPO2 in the perfusate, static lung compliance, and lung peak airway pressure did not differ among the groups. CONCLUSIONS: Infection of S aureus did not affect the lung function during EVLP but induced higher pulmonary artery pressure and pulmonary vascular resistance. Administration of sphingosine effectively eliminated S aureus without side effects in isolated, perfused, and ventilated pig lungs.

An inflammation resolution-promoting intervention prevents atrial fibrillation due to left-ventricular dysfunction.

AIMS: Recent studies suggest that bioactive mediators called resolvins promote active resolution of inflammation. Inflammatory signaling is involved in development of the substrate for atrial fibrillation (AF). To evaluate effects of resolvin-D1 on atrial arrhythmogenic remodeling resulting from left-ventricular dysfunction induced by myocardial infarction (MI) in rats. METHODS AND RESULTS: MI was produced by left anterior descending coronary-artery ligation. Intervention-groups received daily intraperitoneal resolvin-D1, beginning before MI-surgery (early-RvD1) or day-7 post-MI (late-RvD1) and continued until day-21 post-MI. AF-vulnerability was evaluated by electrophysiological study. Atrial conduction was analyzed by optical mapping. Fibrosis was quantified by Masson's trichrome staining; gene-expression by qPCR and RNA-sequencing. Investigators were blinded to group identity.Early-RvD1 significantly reduced MI-size (17 ± 6%, vs. 39 ± 6% in vehicle-MI) and preserved left-ventricular ejection fraction; these were unaffected by late-RvD1. Transesophageal pacing induced atrial tachyarrhythmia in 2/18 (11%) sham-operated rats, vs. 18/18 (100%) MI-only rats, 5/18 (28%, P < 0.001 vs. MI) early-RvD1 MI-rats and 7/12 (58%, P < 0.01) late-RvD1 MI rats. Atrial conduction velocity significantly decreased post-MI; an effect suppressed by RvD1-treatment. Both early- and late-RvD1 limited MI-induced atrial fibrosis and prevented MI-induced increases in atrial expression of inflammation- and fibrosis-related biomarkers and pathways. CONCLUSIONS: RvD1 suppressed MI-related atrial arrhythmogenic remodeling. Early-RvD1 had MI-sparing and atrial-remodeling suppressant effects, whereas late-RvD1 attenuated atrial remodeling and AF-promotion without ventricular protection, revealing atrial-protective actions unrelated to ventricular-function changes. These results point to inflammation-resolution promoting compounds as novel cardioprotective interventions with particular interest in attenuating AF-substrate development.

Hedinger Syndrome-Lessons Learnt: A Single-Center Experience.

BACKGROUND: Hedinger syndrome (HS) or carcinoid heart disease (CD) is a rare and challenging manifestation of malignant neuroendocrine tumours (NETs) involving the heart. We aimed to report our experience with surgical strategies and midterm results in HS patients. METHODS: Eleven patients (58 ± 11 (range 41 to 79 years); 5 females) with HS who underwent cardiac surgery in our department between 07/2005 and 05/2023 were analysed. RESULTS: All patients showed a New York Heart Association (NYHA) class III-IV and in all the tricuspid valve (TV) was involved. Four patients received a TV replacement, and three TV reconstruction. Recently, to preserve the geometry and function of the compromised right ventricle (RV), we have applied the TV "bio-prosthesis in native-valve" implantation technique with the preservation of the valve apparatus (tricuspid valve implantation: TVI) in four cases. Concomitant procedures included pulmonary valve replacement in four, pulmonary implantation in one, and aortic valve replacement in three cases. To treat RV failure, we adapted a combined TandemHeart®-CytoSorb® haemoperfusion strategy in Patient #10 and venoarterial extracorporeal membrane oxygenation (V-A ECMO) support avoidance, after experiencing an ECMO-induced carcinoid-storm-related death in Patient #8. Mortality at 30 days was 18% (2/11). The median follow up was 2 ± 2.1 years (range 1 month to 6 years) with an overall mortality during the follow-up period of 72.7% (8/11). CONCLUSIONS: HS surgery, despite being a high-risk procedure, can efficiently prolong survival, and represents a safe and feasible procedure. However, patient selection seems to be crucial. Further follow up and larger cohorts are needed.

Composition of ex vivo perfusion solutions and kinetics define differential cytokine/chemokine secretion in a porcine cardiac arrest model of lung preservation.

Background: Ex vivo lung perfusion (EVLP) uses continuous normothermic perfusion to reduce ischemic damage and to improve post-transplant outcomes, specifically for marginal donor lungs after the donation after circulatory death. Despite major efforts, the optimal perfusion protocol and the composition of the perfusate in clinical lung transplantation have not been identified. Our study aims to compare the concentration levels of cytokine/chemokine in different perfusion solutions during EVLP, after 1 and 9 h of cold static preservation (CSP) in a porcine cardiac arrest model, and to correlate inflammatory parameters to oxygenation capacities. Methods: Following cardiac arrest, the lungs were harvested and were categorized into two groups: immediate (I-EVLP) and delayed EVLP (D-EVLP), after 1 and 9 h of CSP, respectively. The D-EVLP lungs were perfused with either Steen or modified Custodiol-N solution containing only dextran (CD) or dextran and albumin (CDA). The cytokine/chemokine levels were analyzed at baseline (0 h) and after 1 and 4 h of EVLP using Luminex-based multiplex assays. Results: Within 4 h of EVLP, the concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-1α, and IL-1ß increased significantly (P < 0.05) in all experimental groups. The CD solution contained lower concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-2, IL-12, IL-10, IL-4, IL-1RA, and IL-18 (P < 0.05) compared with those of the Steen solution. The concentration levels of all experimental groups have correlated negatively with the oxygenation capacity values (P < 0.05). Protein concentration levels did not reach statistical significance for I-EVLP vs. D-EVLP and CD vs. CDA solutions. Conclusion: In a porcine cardiac arrest model, a longer period of CSP prior to EVLP did not result in an enhanced protein secretion into perfusates. The CD solution reduced the cytokine/chemokine secretion most probably by iron chelators and/or by the protecting effects of dextran. Supplementing with albumin did not further reduce the cytokine/chemokine secretion into perfusates. These findings may help in optimizing the preservation procedure of the lungs, thereby increasing the donor pool of organs.

Incidence of malignancies after lung transplantation and their effect on the outcome. 26 years' experience.

Background: Malignancy is a significant, life-limiting complication after lung transplantation (LuTx) and the second common long-term cause of death. We aimed to investigate its incidence and effect on the outcome. Methods: This is a retrospective observational study. Between 1996 and 2022, n = 627 lung transplantations (LuTx) were performed in our department. We used our institutional database to identify recipients with malignancies after LuTx and examined the malignancies' incidence and mortality. Results: N = 59 malignancies occurred in n = 55 (8.8%) LuTx recipients. The post-LTx malignancies incidence was 9.4% (59/627). We report the following rates based on their location: n = 17/55 (28,8% of all recipients diagnosed with malignancies) skin, n = 10/55 (16,95%) gastrointestinal, n = 9/55 (15,3%) respiratory, n = 5/55 (8,48%) lymphatic, n = 13/55 (23,6%) other, n = 5 (8,48%) multiple synchronous.During this study period, a total of n = 328 deaths after LuTx was determined. N = 29 (8,84% of all deaths) were malignancy induced, corresponding to a total malignancy-induced mortality of 4.6% (n = 29/627). The majority of deaths were attributed to GI adenocarcinoma and PTLD. Malignancies' origin, primary COPD diagnosis, type, and specific age group were significantly survival-related (p-values <0.05). The most affected organ was skin and showed the best prognosis. PTLD had the fastest and pancreatic the latest onset. Conclusions: This is the first report of its kind in a large cohort of german LuTx recipients. The prevalence ranking of the three commonest malignancy were skin > colorectal > PTLD. Post-LTx malignancy was the second commonest cause of death. Further studies are needed, while post-LuTx malignomas remain a serious impairment of long-term LuTx survival.

Erectile dysfunction and quality of life in patients under left ventricular assist device support - an unspoken issue.

Background: Multiple domains of quality of life (QoL) such as erectile function are not sufficiently investigated among left ventricular assist-device (LVAD) patients. We aimed to evaluate the prevalence of erectile dysfunction (ED) and its association with QoL and depression. Methods: This is a prospective, single-center, cross-sectional study. We included adult male LVAD patients who were clinically stable after at least 3 months post-implantation. Erectile function was assessed with the International Index of Erectile Function (IIEF-5) questionnaire with a score of ≤21 being confirmatory for ED. QoL and depression were estimated with the Kansas City Cardiomyopathy Questionnaire (KCCQ) and the Patient Health Questionnaire depression scale (PHQ-8), respectively. Results: The study included 56 patients, of whom 45 (80 %) met criteria for ED, a prevalence much higher than previously reported in patients with established cardiovascular disease or conservatively treated heart failure. Patients with ED were older and had lower 6-minute walking distance. ED was not associated with comorbidities and heart failure medications but with less frequent use of diuretics and phosphodiesterase-5 inhibitors. There was a correlation between erectile function and depression as well as QoL. Conclusions: These findings underscore that ED deserves special attention and should be included in a multi-targeted approach to address suboptimal QoL outcomes after LVAD implantation.

Reduced Sphingosine in Cystic Fibrosis Increases Susceptibility to Mycobacterium abscessus Infections.

Cystic fibrosis (CF) is an autosomal recessive disorder caused by the deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR) and often leads to pulmonary infections caused by various pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and nontuberculous mycobacteria, particularly Mycobacterium abscessus. Unfortunately, M. abscessus infections are increasing in prevalence and are associated with the rapid deterioration of CF patients. The treatment options for M. abscessus infections are limited, requiring the urgent need to comprehend infectious pathogenesis and develop new therapeutic interventions targeting affected CF patients. Here, we show that the deficiency of CFTR reduces sphingosine levels in bronchial and alveolar epithelial cells and macrophages from CF mice and humans. Decreased sphingosine contributes to the susceptibility of CF tissues to M. abscessus infection, resulting in a higher incidence of infections in CF mice. Notably, treatment of M. abscessus with sphingosine demonstrated potent bactericidal activity against the pathogen. Most importantly, restoration of sphingosine levels in CF cells, whether human or mouse, and in the lungs of CF mice, provided protection against M. abscessus infections. Our findings demonstrate that pulmonary sphingosine levels are important in controlling M. abscessus infection. These results offer a promising therapeutic avenue for CF patients with pulmonary M. abscessus infections.

Chronic kidney disease promotes atrial fibrillation via inflammasome pathway activation.

Chronic kidney disease (CKD) is associated with a higher risk of atrial fibrillation (AF). The mechanistic link between CKD and AF remains elusive. IL-1ß, a main effector of NLR family pyrin domain-containing 3 (NLRP3) inflammasome activation, is a key modulator of conditions associated with inflammation, such as AF and CKD. Circulating IL-1ß levels were elevated in patients with CKD who had AF (versus patients with CKD in sinus rhythm). Moreover, NLRP3 activity was enhanced in atria of patients with CKD. To elucidate the role of NLRP3/IL-1ß signaling in the pathogenesis of CKD-induced AF, Nlrp3-/- and WT mice were subjected to a 2-stage subtotal nephrectomy protocol to induce CKD. Four weeks after surgery, IL-1ß levels in serum and atrial tissue were increased in WT CKD (WT-CKD) mice versus sham-operated WT (WT-sham) mice. The increased susceptibility to pacing-induced AF and the longer AF duration in WT-CKD mice were associated with an abbreviated atrial effective refractory period, enlarged atria, and atrial fibrosis. Genetic inhibition of NLRP3 in Nlrp3-/- mice or neutralizing anti-IL-1ß antibodies effectively reduced IL-1ß levels, normalized left atrial dimensions, and reduced fibrosis and the incidence of AF. These data suggest that CKD creates a substrate for AF development by activating the NLRP3 inflammasome in atria, which is associated with structural and electrical remodeling. Neutralizing IL-1ß antibodies may be beneficial in preventing CKD-induced AF.

Short-term mechanical support with the Impella 5.x for mitral valve surgery in advanced heart failure-protected cardiac surgery.

Introduction: Surgical treatment of patients with mitral valve regurgitation and advanced heart failure remains challenging. In order to avoid peri-operative low cardiac output, Impella 5.0 or 5.5 (5.x), implanted electively in a one-stage procedure, may serve as a peri-operative short-term mechanical circulatory support system (st-MCS) in patients undergoing mitral valve surgery. Methods: Between July 2017 and April 2022, 11 consecutive patients underwent high-risk mitral valve surgery for mitral regurgitation supported with an Impella 5.x system (Abiomed, Inc. Danvers, MA). All patients were discussed in the heart team and were either not eligible for transcatheter edge-to-edge repair (TEER) or surgery was considered favorable. In all cases, the indication for Impella 5.x implantation was made during the preoperative planning phase. Results: The mean age at the time of surgery was 61.6 ± 7.7 years. All patients presented with mitral regurgitation due to either ischemic (n = 5) or dilatative (n = 6) cardiomyopathy with a mean ejection fraction of 21 ± 4% (EuroScore II 6.1 ± 2.5). Uneventful mitral valve repair (n = 8) or replacement (n = 3) was performed via median sternotomy (n = 8) or right lateral mini thoracotomy (n = 3). In six patients, concomitant procedures, either tricuspid valve repair, aortic valve replacement or CABG were necessary. The mean duration on Impella support was 8 ± 5 days. All, but one patient, were successfully weaned from st-MCS, with no Impella-related complications. 30-day survival was 90.9%. Conclusion: Protected cardiac surgery with st-MCS using the Impella 5.x is safe and feasible when applied in high-risk mitral valve surgery without st-MCS-related complications, resulting in excellent outcomes. This strategy might offer an alternative and comprehensive approach for the treatment of patients with mitral regurgitation in advanced heart failure, deemed ineligible for TEER or with need of concomitant surgery.

Fibroblast-specific inflammasome activation predisposes to atrial fibrillation.

Background: Recent work has shown that the NLR-family-pyrin-domain-containing 3 (NLRP3) inflammasome is expressed in cardiomyocytes and when specifically activated causes atrial electrical remodeling and arrhythmogenicity. Whether the NLRP3-inflammasome system is functionally important in cardiac fibroblasts (FBs) remains controversial. In this study, we sought to uncover the potential contribution of FB NLRP3-inflammasome signaling to the control of cardiac function and arrhythmogenesis. Methods: Digital-PCR was performed to determine the expression of NLRP3-pathway components in FBs isolated from human biopsy samples of AF and sinus rhythm patients. NLRP3-system protein expression was determined by immunoblotting in atria of canines with electrically maintained AF. Using the inducible, resident fibroblast (FB)-specific Tcf21-promoter-Cre system (Tcf21iCre as control), we established a FB-specific knockin (FB-KI) mouse model with FB-restricted expression of constitutively active NLRP3. Cardiac function and arrhythmia susceptibility in mice were assessed by echocardiography, programmed electrical stimulation, and optical mapping studies. Results: NLRP3 and IL1B were upregulated in atrial FBs of patients with persistent AF. Protein levels of NLRP3, ASC, and pro-Interleukin-1ß were increased in atrial FBs of a canine AF model. Compared with the control mice, FB-KI mice exhibited enlarged left atria (LA) and reduced LA contractility, a common determinant of AF. The FBs from FB-KI mice were more transdifferentiated, migratory, and proliferative compared to the FBs from control mice. FB-KI mice showed increased cardiac fibrosis, atrial gap junction remodeling, and reduced conduction velocity, along with increased AF susceptibility. These phenotypic changes were supported by single nuclei (sn)RNA-seq analysis, which revealed enhanced extracellular matrix remodeling, impaired communication among cardiomyocytes, and altered metabolic pathways across multiple cell types. Conclusions: Our results show that the FB-restricted activation of the NLRP3-inflammasome system leads to fibrosis, atrial cardiomyopathy, and AF. Activation of NLRP3-inflammasome in resident FBs exhibits cell-autonomous function by increasing the activity of cardiac FBs, fibrosis, and connexin remodeling. This study establishes the NLRP3-inflammasome as a novel FB-signaling pathway contributing to AF pathogenesis.

Vascular complications after peripheral veno-arterial extracorporeal life support cannulation in cardiogenic shock.

Background: Extra Corporeal Life Support (ECLS) is an evolving therapy in therapy-resistant cardiogenic shock (CS). Vascular cannulation in emergency situations can be accomplished through puncture of the femoral vessels by specialised teams. Since lower limb ischemia constitutes one of the major complications following cannulation, a distal perfusion cannula (DPC) has emerged as standard of care. We here aimed to analyse the impact of the DPC on limb perfusion and 6-month survival rate. Methods: In a retrospective study from January 2012 to December 2018, 98 patients with cardiogenic shock and peripheral (v-a) ECLS implantation with documented limb perfusion status were identified and analysed. Demographic data, laboratory parameters, cause of CS, comorbidities, limb perfusion complications and complication management were analysed. Results: 53 patients (54%) received ECLS therapy in referral centers by our mobile ECLS team, while in 45 patients (46%) the cannulation occured in our center. 71 patients (72%) received a DPC (group A) at the time of ECLS implantation, whereas 27 (28%) (group B) did not or received later (14 patients owing to limb ischemia). 44 patients (45%) developed limb ischemia as a complication of ECLS therapy (31% in group A and 81% in group B- p < 0.001). The 6-month survival rate was 28% in our study cohort (30% in group A and 22% in group B- p = 0.469). Conclusion: Lower limb ischemia remains a serious complication after peripheral ECLS cannulation in CS, especially when a DPC is absent. Standardised DPC implementation may reduce the rate of severe limb complications in peripheral ECLS.

Introduction of machine perfusion of donor hearts in a single center in Germany.

Introduction: Organ shortage, subsequent use of extended donor criteria organs and high-risk recipients needing redo-surgery are increasing the complexity of heart transplantation. Donor organ machine perfusion (MP) is an emerging technology allowing reduction of ischemia time as well as standardized evaluation of the organ. The aim of this study was to review the introduction of MP and analyze the results of heart transplantation after MP in our center. Methods: In a retrospective single-center study, data from a prospectively collected database were analysed. From July 2018 to August 2021, fourteen hearts were retrieved and perfused using the Organ Care System (OCS), 12 hearts were transplanted. Criteria to use the OCS were based on donor/recipient characteristics. Primary objective was 30-day survival, secondary objectives were major cardiac adverse events, graft function, rejection episodes as well as overall survival in the follow-up and assessment of MP technical reliability. Results: All patients survived the procedure and the postoperative 30-day interval. No MP related complications were noted. Graft ejection fraction beyond 14 days was ≥ 50% in all cases. Endomyocardial biopsy showed excellent results with no or mild rejection. Two donor hearts were rejected after OCS perfusion and evaluation. Conclusion: Ex vivo normothermic MP during organ procurement is a safe and promising technique to expand the donor pool. Reduction of cold ischemic time while providing additional donor heart assessment and reconditioning options increased the number of acceptable donor hearts. Additional clinical trials are necessary to develop guidelines regarding the application of MP.

Central extracorporeal circulatory life support (cECLS) in selected patients with critical cardiogenic shock.

Background: Percutaneous extracorporeal life support (pECLS) is increasingly applied in cardiogenic shock (CS) despite a lack of evidence from randomized trials. The in-hospital mortality rate of pECLS still reaches up to 60%, while vascular access site complications remain a shortcoming. Surgical approaches with central cannulation for ECLS (cELCS) have emerged as a bail-out option. To date, no systematic approach exists that allows a definition of inclusion or exclusion criteria for cECLS. Methods and results: This single-center, retrospective, case-control study includes all patients fulfilling criteria for CS at the West German Heart and Vascular Center Essen/Germany between 2015 and 2020 who underwent cECLS (n = 58), excluding post-cardiotomy patients. Seventeen patients received cECLS (29.3%) as a first-line treatment strategy and 41 patients as a second-line strategy (70.7%). The main complications leading to the use of cECLS as a second-line strategy were limb ischemia (32.8%) and ongoing insufficient hemodynamic support (27.6%). The first-line cECLS cohort showed a 30-day mortality rate of 53.3% that was constant during follow-up. The 30-day mortality rate of secondary cECLS candidates was 69.8% and the rate at 3 and 6 months was 79.1%. Younger patients (<55 years) were more likely to exhibit survival benefit with cECLS (p = 0.043). Conclusion: Surgical cECLS in CS is a feasible therapy for highly selected patients with hemodynamic instability, vascular complications, or peripheral access site limitations as complementary strategy in experienced centers.

Downregulation of FKBP5 Promotes Atrial Arrhythmogenesis.

BACKGROUND: Atrial fibrillation (AF), the most common arrhythmia, is associated with the downregulation of FKBP5 (encoding FKBP5 [FK506 binding protein 5]). However, the function of FKBP5 in the heart remains unknown. Here, we elucidate the consequences of cardiomyocyte-restricted loss of FKBP5 on cardiac function and AF development and study the underlying mechanisms. METHODS: Right atrial samples from patients with AF were used to assess the protein levels of FKBP5. A cardiomyocyte-specific FKBP5 knockdown mouse model was established by crossbreeding Fkbp5flox/flox mice with Myh6MerCreMer/+ mice. Cardiac function and AF inducibility were assessed by echocardiography and programmed intracardiac stimulation. Histology, optical mapping, cellular electrophysiology, and biochemistry were employed to elucidate the proarrhythmic mechanisms due to loss of cardiomyocyte FKBP5. RESULTS: FKBP5 protein levels were lower in the atrial lysates of patients with paroxysmal AF or long-lasting persistent (chronic) AF. Cardiomyocyte-specific knockdown mice exhibited increased AF inducibility and duration compared with control mice. Enhanced AF susceptibility in cardiomyocyte-specific knockdown mice was associated with the development of action potential alternans and spontaneous Ca2+ waves, and increased protein levels and activity of the NCX1 (Na+/Ca2+-exchanger 1), mimicking the cellular phenotype of chronic AF patients. FKBP5-deficiency enhanced transcription of Slc8a1 (encoding NCX1) via transcription factor hypoxia-inducible factor 1α. In vitro studies revealed that FKBP5 negatively modulated the protein levels of hypoxia-inducible factor 1α by competitively interacting with heat-shock protein 90. Injections of the heat-shock protein 90 inhibitor 17-AAG normalized protein levels of hypoxia-inducible factor 1α and NCX1 and reduced AF susceptibility in cardiomyocyte-specific knockdown mice. Furthermore, the atrial cardiomyocyte-selective knockdown of FKBP5 was sufficient to enhance AF arrhythmogenesis. CONCLUSIONS: This is the first study to demonstrate a role for the FKBP5-deficiency in atrial arrhythmogenesis and to establish FKBP5 as a negative regulator of hypoxia-inducible factor 1α in cardiomyocytes. Our results identify a potential molecular mechanism for the proarrhythmic NCX1 upregulation in chronic AF patients.

Enhanced Ca2+-Dependent SK-Channel Gating and Membrane Trafficking in Human Atrial Fibrillation.

BACKGROUND: Small-conductance Ca2+-activated K+ (SK)-channel inhibitors have antiarrhythmic effects in animal models of atrial fibrillation (AF), presenting a potential novel antiarrhythmic option. However, the regulation of SK-channels in human atrial cardiomyocytes and its modification in patients with AF are poorly understood and were the object of this study. METHODS: Apamin-sensitive SK-channel current (ISK) and action potentials were recorded in human right-atrial cardiomyocytes from sinus rhythm control (Ctl) patients or patients with (long-standing persistent) chronic AF (cAF). RESULTS: ISK was significantly higher, and apamin caused larger action potential prolongation in cAF- versus Ctl-cardiomyocytes. Sensitivity analyses in an in silico human atrial cardiomyocyte model identified IK1 and ISK as major regulators of repolarization. Increased ISK in cAF was not associated with increases in mRNA/protein levels of SK-channel subunits in either right- or left-atrial tissue homogenates or right-atrial cardiomyocytes, but the abundance of SK2 at the sarcolemma was larger in cAF versus Ctl in both tissue-slices and cardiomyocytes. Latrunculin-A and primaquine (anterograde and retrograde protein-trafficking inhibitors) eliminated the differences in SK2 membrane levels and ISK between Ctl- and cAF-cardiomyocytes. In addition, the phosphatase-inhibitor okadaic acid reduced ISK amplitude and abolished the difference between Ctl- and cAF-cardiomyocytes, indicating that reduced calmodulin-Thr80 phosphorylation due to increased protein phosphatase-2A levels in the SK-channel complex likely contribute to the greater ISK in cAF-cardiomyocytes. Finally, rapid electrical activation (5 Hz, 10 minutes) of Ctl-cardiomyocytes promoted SK2 membrane-localization, increased ISK and reduced action potential duration, effects greatly attenuated by apamin. Latrunculin-A or primaquine prevented the 5-Hz-induced ISK-upregulation. CONCLUSIONS: ISK is upregulated in patients with cAF due to enhanced channel function, mediated by phosphatase-2A-dependent calmodulin-Thr80 dephosphorylation and tachycardia-dependent enhanced trafficking and targeting of SK-channel subunits to the sarcolemma. The observed AF-associated increases in ISK, which promote reentry-stabilizing action potential duration shortening, suggest an important role for SK-channels in AF auto-promotion and provide a rationale for pursuing the antiarrhythmic effects of SK-channel inhibition in humans.

Phosphodiesterase 8 governs cAMP/PKA-dependent reduction of L-type calcium current in human atrial fibrillation: a novel arrhythmogenic mechanism.

AIMS: Atrial fibrillation (AF) is associated with altered cAMP/PKA signaling and an AF-promoting reduction of L-type Ca2+-current (ICa,L), the mechanisms of which are poorly understood. Cyclic-nucleotide phosphodiesterases (PDEs) degrade cAMP and regulate PKA-dependent phosphorylation of key calcium-handling proteins, including the ICa,L-carrying Cav1.2α1C subunit. The aim was to assess whether altered function of PDE type-8 (PDE8) isoforms contributes to the reduction of ICa,L in persistent (chronic) AF (cAF) patients. METHODS AND RESULTS: mRNA, protein levels, and localization of PDE8A and PDE8B isoforms were measured by RT-qPCR, western blot, co-immunoprecipitation and immunofluorescence. PDE8 function was assessed by FRET, patch-clamp and sharp-electrode recordings. PDE8A gene and protein levels were higher in paroxysmal AF (pAF) vs. sinus rhythm (SR) patients, whereas PDE8B was upregulated in cAF only. Cytosolic abundance of PDE8A was higher in atrial pAF myocytes, whereas PDE8B tended to be more abundant at the plasmalemma in cAF myocytes. In co-immunoprecipitation, only PDE8B2 showed binding to Cav1.2α1C subunit which was strongly increased in cAF. Accordingly, Cav1.2α1C showed a lower phosphorylation at Ser1928 in association with decreased ICa,L in cAF. Selective PDE8 inhibition increased Ser1928 phosphorylation of Cav1.2α1C, enhanced cAMP at the subsarcolemma and rescued the lower ICa,L in cAF, which was accompanied by a prolongation of action potential duration at 50% of repolarization. CONCLUSION: Both PDE8A and PDE8B are expressed in human heart. Upregulation of PDE8B isoforms in cAF reduces ICa,L via direct interaction of PDE8B2 with the Cav1.2α1C subunit. Thus, upregulated PDE8B2 might serve as a novel molecular mechanism of the proarrhythmic reduction of ICa,L in cAF.

Five-year follow-up of mitral valve repair versus replacement: a propensity score analysis.

BACKGROUND: Mitral valve repair (MVRe) is considered to have a superior outcome compared to replacement (MVRp) in patients with mitral valve regurgitation (MVR). It was the aim of the study to analyse the clinical results and identify risk factors for short and long-term mortality. METHODS: In a retrospective single-center analysis, patients undergoing an isolated mitral valve procedure from June 2010 to December 2016 were identified. These were subsequently homogenized using 10 baseline characteristics for propensity-score matching. Comparative analyses were performed for early and long-term results, using adequate statistical tools, and identifying risk factors for the investigated endpoints, primary end-point: all-cause mortality within 5 years and secondary end-points: recurrent MVR, reoperation, endocarditis and/or mortality with 30 days, 1, 3 and 5 years. RESULTS: 241 patients were identified in the entire patient cohort. After matching, patients were divided into 2 groups of 64 each respectively. The median age was similar in the two groups. There was a significant interaction between early mortality risk of MV in patients with coronary artery disease (CAD) (OR 11.94, 95% CI 1.49-285.92, p = 0.04) and late mortality in patients with higher EuroSCORE II (HR 1.14, 95% CI 1.06-1.23, p < 0.001). The primary end-point showed 5-year survival rate was significantly higher in MVRe versus MVRp (90.06% vs. 79.54% respectively, p = 0.04). The secondary end-point demonstrated recurrent MVR not to be statistically significant between the 2 groups (p = 0.09) as well as reoperation (p = 0.28). Endocarditis was observed in one patient after MVRp. CONCLUSIONS: We concluded MVRe to be associated with lower operative and 5-year mortality and good postoperative outcomes compared to patients undergoing MVRp. Concomitant CAD was identified as one of the risk factors for increasing the in-hospital mortality rate. There was no significant difference in rehospitalisation over the follow-up period. MVRe should be the treatment of choice for severe MVR and should remain a central aspect in valve centers' treatment algorithms and quality measures.

Prevention of Mitral Ring Dehiscence by a Simple Modification of Suture Placement.

Ring dehiscence is a serious complication after mitral valve annuloplasty, tending to occur primarily from the posterior annulus. The tension on the ring sutures during the cardiac cycle is one of the suspected reasons; to minimize this tension, we apply four additional pledgeted sutures positioned supra-annularly at critical hinge points and could achieve a marked reduction of annular dehiscence since.