Sudden Death In Adults Research Articles

Abstract Su706: New risk markers of sudden cardiac death in the young : insights from machine learning on EHR data

Background: Sudden Cardiac Death (SCD) in young adults is a significant public health issue, with survival rates often less than 15%. Effective prevention is critical as many SCD cases go undetected due to nonspecific symptoms and ineffective risk stratification methods, especially among the youth. Objective: To explore risk markers specific to SCD in younger populations using Artificial Intelligence (AI) trained on systematically collected Electronic Health Records (EHR) data, and to compare these markers with those in older populations. Methods: We conducted a retrospective cohort study using data from 46,060 participants in Paris and its inner suburbs, spanning 2011 to 2020. The cohort included 1,100 SCD cases and 1,100 controls aged 40 years or younger, and 21,930 SCD cases and 21,930 controls aged over 40. A machine learning model was developed, trained, and validated on these cohorts. We used the Catboost algorithm and evaluated model performance using AUC, sensitivity, and specificity. The SHAP algorithm was employed to elucidate the relationship between variables and predicted risk. Results: The model achieved on validation sets an AUC of 0.75 (95% CI 0.67-0.83) for the younger cohort and AUC of 0.82 (95% CI: 0.70-0.83), for the older cohort. Neuropsychiatric drugs were the most influential predictors for the younger cohort, whereas age and cardiovascular drugs were most predictive for the older cohort. The results indicate that traditional cardiovascular risk factors play a secondary role in predicting SCD among younger individuals. Conclusion: In analyzing predictors of sudden death in individuals under 40, we developed a personalized SCD prediction model using EHR data tailored to this demographic. Psychiatric medications, and possibly underlying psychiatric conditions, emerged as significant predictors. Our findings emphasize the need for a multidisciplinary approach to SCD prevention, integrating neuropsychiatric and cardiovascular considerations.

Abstract 4134426: Targeting the TRIM29-PERK signaling axis for treating viral myocarditis

Introduction: Viral myocarditis is an inflammatory disease of the myocardium that significantly contributes to sudden death in children and young adults. The COVID-19 pandemic underscores the critical need to understand the pathogenesis and develop effective treatment strategies for viral myocarditis. Methods: To investigate the role of the novel E3 ligase TRIM29 in viral myocarditis, we used wild-type and TRIM29 knockout mice infected with coxsackievirus B3 (CVB3) and encephalomyocarditis virus (EMCV), to induce the myocarditis. Additionally, wild-type mice infected with CVB3 were treated with the protein kinase RNA-like endoplasmic reticulum kinase (PERK) inhibitor GSK2656157 or a DMSO control to evaluate potential therapeutic interventions. Mice survival and heart function were monitored using transthoracic echocardiography, and hearts were harvested for histological and immunohistochemical analysis. Techniques including real-time PCR, western blotting, co-immunoprecipitation, enzyme-linked immunoassay, flow cytometry, over-expression, and knockdown were employed to elucidate the pathogenic mechanisms by which TRIM29 regulates the endoplasmic reticulum stress response after viral infection. Results: We found that TRIM29 was highly induced by cardiotropic viruses, including CVB3 and EMCV, and promoted PERK-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses, which restricted viral replication in cardiomyocytes in vitro . TRIM29 deficiency protected mice from viral myocarditis by enhancing cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive cells in vivo . Mechanistically, TRIM29 interacted with PERK to catalyze the SUMOylation of PERK, maintaining its stability and thereby promoting PERK-mediated signaling pathways. Furthermore, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK interaction, which improved cardiac function, enhanced cardiac antiviral responses, and reduced inflammation and immunosuppressive cells in vivo . Conclusions: Our findings provide the first evidence that the TRIM29-PERK signaling axis can be targeted for the treatment of viral myocarditis. This suggests that targeting the TRIM29-PERK axis could effectively mitigate viral myocarditis and associated cardiovascular diseases.

Current approaches and future perspectives on hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder characterized by significant myocardial hypertrophy and varying degrees of fibrosis, affecting approximately 0.2% of the general population, with a higher prevalence in those with cardiac conditions. Despite its frequency, HCM remains underdiagnosed due to its broad clinical spectrum. The disease is equally prevalent in men and women, presenting in forms ranging from mild to severe, and it is the leading cause of sudden cardiac death in adolescents and young adults, particularly athletes. Recent advances in genetic engineering and biotechnology have significantly improved the understanding, diagnosis, and treatment of HCM, emphasizing the importance of early diagnosis in preventing severe complications. This review synthesizes findings from a narrative literature review, highlighting advances in risk stratification, gene therapy, biomarker utilization, and the need for further research to make these innovations more widely available in clinical practice. The study also examines the disease's pathophysiology, genetics, diagnostic methods, and treatment strategies, underlining the importance of personalized approaches to managing HCM.

A Rare Noncoding Enhancer Variant in SCN5A Contributes to the High Prevalence of Brugada Syndrome in Thailand.

Brugada syndrome (BrS) is a cardiac arrhythmia disorder that causes sudden death in young adults. Rare genetic variants in the SCN5A gene encoding the Nav1.5 sodium channel and common noncoding variants at this locus are robustly associated with the condition. BrS is particularly prevalent in Southeast Asia but the underlying ancestry-specific factors remain largely unknown. Genome sequencing of BrS probands and population-matched controls from Thailand was performed to identify rare noncoding variants at the SCN5A-SCN10A locus that were enriched in patients with BrS. A likely causal variant was prioritized by computational methods and introduced into human induced pluripotent stem cell (hiPSC) lines using CRISPR-Cas9. The effect of the variant on SCN5A expression and Nav1.5 sodium channel current was then assessed in hiPSC-derived cardiomyocytes (hiPSC-CMs). A rare noncoding variant in an SCN5A intronic enhancer region was highly enriched in patients with BrS (detected in 3.9% of cases with a case-control odds ratio of 45.2). The variant affects a nucleotide conserved across all mammalian species and predicted to disrupt a Mef2 transcription factor binding site. Heterozygous introduction of the enhancer variant in hiPSC-CMs caused significantly reduced SCN5A expression from the variant-containing allele and a 30% reduction in Nav1.5-mediated sodium current density compared with isogenic controls, confirming its pathogenicity. Patients with the variant had severe phenotypes, with 89% experiencing cardiac arrest. This is the first example of a functionally validated rare noncoding variant at the SCN5A locus and highlights how genome sequencing in understudied populations can identify novel disease mechanisms. The variant partly explains the increased prevalence of BrS in this region and enables the identification of at-risk variant carriers to reduce the burden of sudden cardiac death in Thailand.

Desmoplakin CSM models unravel mechanisms regulating the binding to intermediate filaments and putative therapeutics for cardiocutaneous diseases.

Arrhythmogenic cardiomyopathy (AC) is a common cause of sudden cardiac arrest and death in young adults. It can be induced by different types of mutations throughout the desmoplakin gene including the R2834H mutation in the extreme carboxyterminus tail of desmoplakin (DP CT) which remains structurally uncharacterized and poorly understood. Here, we have created 3D models of DP CT which show the structural effects of AC-inducing mutations as well as the implications of post-translational modifications (PTMs). Our results suggest that, in absence of PTMs, positively charged wildtype DP CT likely folds back onto negatively-charged plectin repeat 14 of nearby plakin repeat domain C (PRD C) contributing to the recruitment of intermediate filaments (IFs). When phosphorylated and methylated, negatively-charged wildtype DP CT would then fold back onto positively-charged plectin repeat 17 of PRD C, promoting the repulsion of intermediate filaments. However, by preventing PTMs, the R2834H mutation would lead to the formation of a cytoplasmic mutant desmoplakin with a constitutively positive DP CT tail that would be aberrantly recruited by cytoplasmic IFs instead of desmosomes, potentially weakening cell-cell contacts and promoting AC. Virtual screening of FDA-approved drug libraries identified several promising drug candidates for the treatment of cardiocutaneous diseases through drug repurposing.

Association between cardiovascular risk factors and dilated and hypertrophic cardiomyopathy: Mendelian randomization analysis

Backgroundand aims: Dilated cardiomyopathy is a major cause of heart failure, and hypertrophic cardiomyopathy is a common cause of sudden cardiac death in young adults. Epidemiological studies reporting the association between these cardiomyopathies and common cardiovascular risk factors, including smoking, alcohol, and obesity, are limited, and the published studies are mostly observational, making them vulnerable to bias. Methods and resultsWe performed a two-sample Mendelian randomization analysis to assess whether cardiovascular risk factors were causally associated with dilated and hypertrophic cardiomyopathies. Independent genetic variants associated with body mass index, smoking, and alcohol were selected as instrumental variables, with two sets of instrumental variables utilized for alcohol. Dilated cardiomyopathy data on 355,318 samples and hypertrophic cardiomyopathy data on 489,727 samples were obtained from a European population-based genome-wide association study (GWAS) meta-analysis. The large GWAS data sample size improved the statistical power. Our results showed significant associations between a genetic predisposition for smoking and the risk of dilated cardiomyopathy (odds ratio (OR) = 1.33; 95% confidence level (CI): 1.07–1.67; p = 0.012) and between a genetic predisposition for obesity and the risk of dilated cardiomyopathy (OR = 1.62; 95% CI, 1.30 – 2.02; p = 1.51 × 10-5). The results of the other associations were not significant. ConclusionsThis study suggests that smoking and obesity are causally associated with an increased risk of dilated cardiomyopathy.

Abstract We119: Treatment of Viral Myocarditis by Targeting the TRIM29-PERK Axis-Mediated ER Stress Immune Response

Viral myocarditis, an inflammatory disease of the myocardium, is a significant cause of sudden death in children and young adults. The current coronavirus disease 19 pandemic emphasizes the need to understand the pathogenesis mechanisms and potential treatment strategies for viral myocarditis. Here, we found that TRIM29 was highly induced by cardiotropic viruses and promoted protein kinase RNA-like endoplasmic reticulum kinase (PERK)-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses that promote viral replication in cardiomyocytes in vitro . TRIM29 deficiency protected mice from viral myocarditis by promoting cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive monocytic myeloid-derived suppressor cells (mMDSC) in vivo . Mechanistically, TRIM29 interacted with PERK to promote SUMOylation of PERK to maintain its stability, thereby promoting PERK-mediated signaling pathways. Finally, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK connection, thereby bolstering cardiac function, enhancing cardiac antiviral responses, and curbing inflammation and immunosuppressive mMDSC in vivo . Our findings offer insight into how cardiotropic viruses exploit TRIM29-regulated PERK signaling pathways to instigate viral myocarditis, suggesting that targeting the TRIM29-PERK axis could mitigate disease severity.

Idiopathic Ventricular Fibrillation - Just How Much Idiopathic is it?

Idiopathic ventricular fibrillation is diagnosed in survivors of sudden cardiac death that has been caused by ventricular fibrillation without known structural or electrical abnormalities, even after extensive investigation. It is a common cause of sudden death in young adults. Although idiopathic ventricular fibrillation is a diagnosis of exclusion, in many cases only a partial investigation algorithm is performed. The aim of this review is to present a comprehensive diagnostic evaluation algorithm with a focus on diagnostic assessment of inherited arrhythmic syndromes and genetic background.

Myocardial infarction as a cause of sudden death in healthy young adults- A post mortem study

Myocardial infarction as a cause of sudden death in healthy young adults- A post mortem study

Cardiac channelopathies in the context of hereditary arrhythmia syndromes

Genetic arrhythmia disorders are rare diseases; however, they are acommon cause of sudden cardiac death in children, adolescents, and young adults. In principle, adistinction can be made between channelopathies and cardiomyopathies in the context of genetic diseases. This paper focuses on the channelopathies long and short QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT). Early diagnosis of these diseases is essential, as drug therapy, behavioral measures, and if necessary, implantation of acardioverter defibrillator can significantly improve the prognosis and quality of life of patients. This paper highlights the pathophysiological and genetic basis of these channelopathies, describes their clinical manifestations, and comments on the principles of diagnosis, risk stratification and therapy.

Combination of arrythmogenic right ventricular cardiomyopathy with Loeys-Dietz syndrome: case report

Arrhythmogenic right ventricular dysplasia is a hereditary cardiomyopathy - a common cause of sudden cardiac death in children and young adults. Loeys-Dietz syndrome is an ultra-rare connective tissue disorder characterized by aneurysms of the aorta and other large arteries, arterial tortuosity, and joint hypermobility and is associated with pathogenic variants in genes encoding protein components TGF-β pathway. We present a rare case of a two-abovementioned genetic disorders combination in a proband with a complex and rapidly progressive cardiovascular syndrome.

BRUGADA SYNDROME: NEWEST DATA ON RISK STRATIFICATION

Abstract Background Brugada Syndrome (BrS) is a rare genetically based channelopathy responsible for malignant arrhythmias and sudden cardiac death (SCD) in young adults. Objectives The aims was to evaluate prognostic indicators useful for accurate arrhythmic risk stratification in BrS by studying genetic, clinical, anamnestic, instrumental parameters, and those derived from electrophysiological study (EPS) and intracavitary mapping. Materials and Methods 209 patients with Brugada type 1 were recruited between 01/01/2018 and 01/10/2023. Results In the first study, predictive factors related to high arrhythmic risk from the data obtained for the total population of 209 Brugada patients enrolled in our case series include a positive history of cardiogenic syncope (p value 0.000041), having had a resuscitated cardiac arrest (p value 0.00025), presenting positive EPS for inducibility of ventricular tachycardia (p value 0.00032), having a family history of sudden cardiac death (p value < 0.00001), and presenting positive cardiac mapping and MRI for pathological alterations (both with p value > 0.00001). From the data obtained for the subset of 80 Brugada patients with ICD in our case series, predictive factors related to high arrhythmic risk are different from the previously analyzed population: presenting spontaneous type 1 ECG (p value 0.0015), having had a resuscitated cardiac arrest (p value 0.014028), having a family history of sudden cardiac death (p value < 0.00001), and presenting positive mapping, genetics, and cardiac MRI for pathological alterations. Positive EPS and syncope in this subset do not appear to be risk factors, unlike the population of all 209 enrolled patients. Conclusions Multiparametric scores, including the mentioned markers, have been introduced in clinical practice for a better approach in selection. However, new markers are needed to improve risk stratification in BrS patients, especially those in the so–called "gray zone" with intermediate risk. In the future, it will be evaluated through experimental models and genotype–phenotype integration whether such electrical heterogeneity is also associated with specific genetic or structural abnormalities and may represent a new therapeutic target for etiological treatment in BrS patients. In conclusion, there is an urgent need to develop new methods for risk stratification in Brugada syndrome that are sufficiently sensitive, specific, reproducible, and easy to apply.

Loss of TRIM29 mitigates viral myocarditis by attenuating PERK-driven ER stress response in male mice

Viral myocarditis, an inflammatory disease of the myocardium, is a significant cause of sudden death in children and young adults. The current coronavirus disease 19 pandemic emphasizes the need to understand the pathogenesis mechanisms and potential treatment strategies for viral myocarditis. Here, we found that TRIM29 was highly induced by cardiotropic viruses and promoted protein kinase RNA-like endoplasmic reticulum kinase (PERK)-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses that promote viral replication in cardiomyocytes in vitro. TRIM29 deficiency protected mice from viral myocarditis by promoting cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive monocytic myeloid-derived suppressor cells (mMDSC) in vivo. Mechanistically, TRIM29 interacted with PERK to promote SUMOylation of PERK to maintain its stability, thereby promoting PERK-mediated signaling pathways. Finally, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK connection, thereby bolstering cardiac function, enhancing cardiac antiviral responses, and curbing inflammation and immunosuppressive mMDSC in vivo. Our findings offer insight into how cardiotropic viruses exploit TRIM29-regulated PERK signaling pathways to instigate viral myocarditis, suggesting that targeting the TRIM29-PERK axis could mitigate disease severity.

Genetics in the diagnosis and treatment of cardiovascular diseases

Cardiovascular diseases (CVDs) remain one of the leading causes of morbidity and mortality worldwide, with genetics being a major risk factor. Genetic cardiovascular disease can occur either because of single variant (Mendelian) or polygenic influences and has been linked to inherited cardiovascular conditions (ICC) such as arrhythmias, cardiomyopathies, dyslipidemias, and aortopathies which are significant factors leading to sudden cardiac death in young adults. Timely screening, diagnosis, and management of ICC can not only provide life-saving treatment to a patient, but also identify at-risk family members. The field of pharmacogenomics (PGx) helped to understand the variable action of medications such as clopidogrel, aspirin, warfarin, and statin according to genotype. Newer technologies such as multi-omics can combine data from multiple sources such as genomics, epigenomics, transcriptomics, proteomics, metabolomics, and microbiome. These advancements can contribute to the development of polygenic prediction scores and precision medicine tailored to individual genotypes. Substantial strides have been made in genetic-based therapeutics, gene editing technologies, and drug delivery systems, which have significantly expanded treatment options for patients with acquired or inherited CVDs. Although variable, the country- and society-specific guidelines on genetic testing for ICC and PGx and treatment are being continuously updated to keep up with ongoing research in the field. Along with appropriate knowledge, other factors including cost and availability of genetic testing play a vital role in the usage by both physicians and patients. With the advent of newer genetic testing for CVDs, a key factor is the availability of genetic counselors (GCs) who are specifically trained in cardiovascular genomics. The current review provides a concise summary of the major influences of genetics in the diagnosis and treatment of CVDs.

Cardiac-Specific Deletion of Scn8a Mitigates Dravet Syndrome-Associated Sudden Death in Adults

BackgroundSudden unexpected death in epilepsy (SUDEP) is a fatal complication experienced by otherwise healthy epilepsy patients. Dravet syndrome (DS) is an inherited epileptic disorder resulting from loss of function of the voltage-gated sodium channel, NaV 1.1, and is associated with particularly high SUDEP risk. Evidence is mounting that NaVs abundant in the brain also occur in the heart, suggesting that the very molecular mechanisms underlying epilepsy could also precipitate cardiac arrhythmias and sudden death. Despite marked reduction of NaV 1.1 functional expression in DS, pathogenic late sodium current (INa,L) is paradoxically increased in DS hearts. However, the mechanisms by which DS directly impacts the heart to promote sudden death remain unclear. ObjectivesIn this study, the authors sought to provide evidence implicating remodeling of Na+ - and Ca2+ -handling machinery, including NaV 1.6 and Na+/Ca2+exchanger (NCX) within transverse (T)-tubules in DS-associated arrhythmias. MethodsThe authors undertook scanning ion conductance microscopy (SICM)-guided patch clamp, super-resolution microscopy, confocal Ca2+ imaging, and in vivo electrocardiography studies in Scn1a haploinsufficient murine model of DS. ResultsDS promotes INa,L in T-tubular nanodomains, but not in other subcellular regions. Consistent with increased NaV activity in these regions, super-resolution microscopy revealed increased NaV 1.6 density near Ca2+release channels, the ryanodine receptors (RyR2) and NCX in DS relative to WT hearts. The resulting INa,L in these regions promoted aberrant Ca2+ release, leading to ventricular arrhythmias in vivo. Cardiac-specific deletion of NaV 1.6 protects adult DS mice from increased T-tubular late NaV activity and the resulting arrhythmias, as well as sudden death. ConclusionsThese data demonstrate that NaV 1.6 undergoes remodeling within T-tubules of adult DS hearts serving as a substrate for Ca2+ -mediated cardiac arrhythmias and may be a druggable target for the prevention of SUDEP in adult DS subjects.

Acute Adenoviral Infection Elicits an Arrhythmogenic Substrate Prior to Myocarditis.

Viral cardiac infection represents a significant clinical challenge encompassing several etiological agents, disease stages, complex presentation, and a resulting lack of mechanistic understanding. Myocarditis is a major cause of sudden cardiac death in young adults, where current knowledge in the field is dominated by later disease phases and pathological immune responses. However, little is known regarding how infection can acutely induce an arrhythmogenic substrate before significant immune responses. Adenovirus is a leading cause of myocarditis, but due to species specificity, models of infection are lacking, and it is not understood how adenoviral infection may underlie sudden cardiac arrest. Mouse adenovirus type-3 was previously reported as cardiotropic, yet it has not been utilized to understand the mechanisms of cardiac infection and pathology. We have developed mouse adenovirus type-3 infection as a model to investigate acute cardiac infection and molecular alterations to the infected heart before an appreciable immune response or gross cardiomyopathy. Optical mapping of infected hearts exposes decreases in conduction velocity concomitant with increased Cx43Ser368 phosphorylation, a residue known to regulate gap junction function. Hearts from animals harboring a phospho-null mutation at Cx43Ser368 are protected against mouse adenovirus type-3-induced conduction velocity slowing. Additional to gap junction alterations, patch clamping of mouse adenovirus type-3-infected adult mouse ventricular cardiomyocytes reveals prolonged action potential duration as a result of decreased IK1 and IKs current density. Turning to human systems, we find human adenovirus type-5 increases phosphorylation of Cx43Ser368 and disrupts synchrony in human induced pluripotent stem cell-derived cardiomyocytes, indicating common mechanisms with our mouse whole heart and adult cardiomyocyte data. Together, these findings demonstrate that adenoviral infection creates an arrhythmogenic substrate through direct targeting of gap junction and ion channel function in the heart. Such alterations are known to precipitate arrhythmias and likely contribute to sudden cardiac death in acutely infected patients.

Myocarditis in children.Etiology. Pathogenesis. Epidemiology. Clinical presentation

Readers will be presented with a series of articles on myocarditis in children, which are based on clinical guidelines developed by a group of authors on this topic. Myocarditis is an inflammatory myocardial disease characterized by a wide range of clinical manifestations — from minor to sudden cardiac death. Given the absence of pathognomonic symptoms, as well as the similarity of manifestations in the onset with common childhood diseases such as respiratory distress, gastrointestinal diseases, infectious pathology, specialists often overlook the likelihood of a diagnosis of “myocarditis”, which causes a late start of therapy and an adverse outcome. Considering that myocarditis accounts for 12% of cases of sudden cardiac death in adolescents and young adults, suspicion of this disease in differential diagnosis in children with nonspecific symptoms and disease progression may be the key to the formation of a proper treatment strategy. Despite significant advances in the study of myocarditis in both adults and children, there are still many unresolved issues. The purpose of this article is to highlight the current view of the etiology, pathogenesis, epidemiology and clinical features in children with various types of myocarditis in order to increase the knowledge of practitioners for better clinical management of patients with myocarditis.

Macrophage membrane-modified targeted phase-change nanoparticles for multimodal imaging of experimental autoimmune myocarditis.

Myocarditis is an important public health issue due to the high prevalence of sudden death in adolescents and young adults. Nevertheless, the early identification of myocarditis remains a serious problem for clinicians. There is no single non-invasive method to diagnose myocarditis in the currently available clinical guidelines and consensus. Molecular imaging is an effective approach for accurate diagnosis. Poly(lactic acid-glycolic acid) (PLGA) is considered to be the preferred carrier for molecular imaging because of its biosafety and modifiability. Macrophage membrane-modified biomimetic nanoprobes (MM-NPs) possess low immunogenicity and inflammation-directed chemotaxis capabilities and are repeatedly chosen as materials for targeted diagnosis and treatment of inflammatory diseases. In this study, experimental autoimmune myocarditis (EAM) was used as an animal model of inflammation. Previous studies have confirmed that this model is similar to pathological injury caused by acute myocarditis in humans. In multimodal imaging (US/PA/MRI), a phase-change material (PFH) and superparamagnetic iron oxide (SPIO) are used as imaging substances. Early identification of myocardial inflammatory sites was achieved by the tail vein injection of MM/NPs loaded with PFH and SPIO. This probe is expected to be a powerful tool for clinicians to diagnose myocarditis.

Association between anti-cardiac autoantibodies in acute myocarditis and downstream clinical outcomes

Abstract Introduction Myocarditis is an inflammatory heart muscle disease that can result in cardiac dysfunction and arrhythmias. Its aetiology includes infectious, toxic or autoimmune causes. Myocarditis is responsible for sudden cardiac death in young adults (1) and can result in heart failure due to dilated cardiomyopathy in 20% of patients (2). The pathogenesis of myocarditis may involve immune system dysregulation leading to a cascade of inflammation and myocardial damage (3). For those patients that rapidly progress to end-stage dilated cardiomyopathy, an important dilemma is whether there is any prospect of heart function recovery. Therefore, there is an unmet need for a better understanding of key causal pathways and for developing a biological signature of disease progression. Hypothesis The progression of acute myocarditis depends on a persistent adaptive immune response against the heart, leading to ongoing inflammation, myocardial fibrosis and ultimately tissue destruction and remodelling. Aims We sought to explore anti-cardiac IgG serum levels, their temporal profile throughout follow up and their association with clinical and imaging data, in patients presenting with acute myocarditis. Methods We prospectively recruited 80 patients with a clinical diagnosis of acute myocarditis. We measured their total anti-cardiac IgG levels at admisssion, 3- and 12-months follow-up using an enzyme-linked immunosorbent assay (ELISA). We explored the association between the anti-cardiac IgG levels, cardiac MRI parameters (CMR) and clinical data. Results We detect an adaptive immune response against the heart in a subgroup of patients with acute myocarditis. 20% of patients develop high systemic titres of anti-cardiac IgG (OD threshold >0.65), within the first 7 days of presentation (Figure 1a). These patients continue to have persistent and significantly higher anti-cardiac IgG levels at 12 months (Figure 1b). Importantly, patients that mount a strong initial adaptive immune response against the heart, are more likely to show evidence of persistent oedema on CMR at 12 months(Figure 1c). Clinical event rates in our cohort have remained low at five-year follow-up. A small signal exists to indicate potentially higher rates of persistent symptoms (70% vs 47%), hospitalisations for heart failure (12% vs 8%) and new heart failure diagnosis (18% vs 11%), in patients that mount a strong adaptive immune response compared to those that do not. Conclusion A subset of patients with acute myocarditis develops a strong and persistent adaptive immune response against the heart. This may be associated with more myocardial oedema on cardiac MRI, persistent symptoms and higher rates of heart failure diagnoses and hospitalisations. Further work Plasma proteomics (targeted and un-targeted discovery) with validation in myocardial tissue. Analysis of CMR data with a focus on fibrosis assessment. ELISA for IgG subtypes and total IgG against myosin and troponin I.

Abstract 13301: TRIM29 Causes Pathogenesis of Viral Myocarditis by Inducing PERK-Mediated Endoplasmic Reticulum Stress and Reactive Oxygen Species Responses

Introduction: Viral myocarditis is an inflammatory disease of the myocardium which contributes to a significant fraction of sudden death in children and young adults. The ongoing coronavirus disease 19 pandemic emphasizes the need for understanding the pathogenesis mechanisms and potential treatment strategies for viral myocarditis. Methods: To understand the role of the novel E3 ligase TRIM29 in controlling viral myocarditis, wild-type and TRIM29 knockout mice were infected with coxsackievirus B3 (CVB3) for inducing viral myocarditis. Mice survival and heart function were monitored by transthoracic echocardiography, and hearts were harvested for histology and immunohistochemistry analysis. Real-time PCR, western blotting, co-immunoprecipitation, enzyme-linked immunoassay, flow cytometry, over-expression and knockdown techniques were used to understand the pathogenic mechanisms of TRIM29 in regulating endoplasmic reticulum stress response after virus infection in this study. Results: We found that TRIM29 was highly induced by cardiotropic viruses, including CVB3 and encephalomyocarditis (EMCV), and promoted protein kinase RNA-like endoplasmic reticulum kinase (PERK) mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses that restrict viral replication in cardiomyocytes in vitro . TRIM29 deficiency protected mice from viral myocarditis by promoting cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive cells in vivo . Mechanistically, TRIM29 interacted with PERK to catalyze SUMOylation of PERK for maintaining its stability, thereby promoting PERK-mediated signaling pathways. Conclusions: Our data provide the first evidence that TRIM29-mediated PERK signaling pathways cause pathogenesis of viral myocarditis and identify the TRIM29-PERK axis as a potential therapeutic target for treating viral induced cardiovascular diseases.