Myocarditis

Advances in the diagnosis of myocarditis in idiopathic inflammatory myopathies: an overview of diagnostic tests

Cardiac involvement in idiopathic inflammatory myopathies (IIM) purports to worse clinical outcomes, and therefore early identification is important. Research has focused on blood biomarkers and basic investigations such as ECG and echocardiography, which have the advantage of wide availability and low cost but are limited in their sensitivity and specificity. Imaging the myocardium to directly look for inflammation and scarring has therefore been explored, with a number of new methods for doing this gaining wider research interest and clinical availability. Cardiovascular magnetic resonance (CMR) with contemporary multiparametric mapping techniques and late gadolinium enhancement imaging, is an extremely valuable and increasingly used non-invasive imaging modality for the diagnosis of myocarditis. The recently updated CMR-based Lake Louise Criteria for the diagnosis of myocarditis incorporate the newer T1 and T2 mapping techniques, which have greatly improved the diagnostic accuracy for IIM myocarditis.18F-FDG-PET/CT is a well-utilized imaging modality in the diagnosis of malignancies in IIM, and it also has a role for the diagnosis of myocarditis in multiple systemic inflammatory diseases. Endomyocardial biopsy, however, remains the gold standard technique for the diagnosis of myocarditis and is necessary for the diagnosis of specific cases of myocarditis. This article provides an overview of the important tests and imaging modalities that clinicians should consider when faced with an IIM patient with potential myocarditis.

Global burden of myocarditis in youth and middle age (1990-2019): A systematic analysis of the disease burden and thirty-year forecast

BACKGROUND

Myocarditis is increasingly recognized as a critical health issue, particularly among youth and middle-aged populations. This study aims to analyze the global burden and trends of myocarditis in these age groups to emphasize the need for region-specific prevention and treatment strategies.

METHODS

Using data from the Global Burden of Disease (GBD) study (1990-2019), we evaluated the age-standardized rates (ASR) of myocarditis in individuals aged 10 to 54 years. We calculated average annual percentage changes (AAPC) and estimated annual percentage changes (EAPC). Additionally, we examined the correlation between myocarditis incidence and the Human Development Index (HDI) and Socio-demographic Index (SDI). Age and sex trends in myocarditis were analyzed, and Bayesian age-period-cohort (BAPC) models were used to forecast prevalence trends up to 2050.

RESULTS

The High-income Asia Pacific region had the highest ASR of myocarditis, while North Africa and the Middle East had the lowest. North Africa and the Middle East also experienced the fastest average annual growth in ASR, whereas High-income North America saw the most significant decline. Correlational analysis showed that countries with a high SDI exhibited higher myocarditis ASR. The burden of myocarditis was greater among males than females, with this disparity increasing with age. Projections indicate a stable trend in the incidence of myocarditis among the youth and middle-aged population up to 2050, although the total number of cases is expected to rise.

CONCLUSION

Our study reveals a significant upward trend in myocarditis among youth and middle-aged populations, highlighting the urgency for early monitoring and preventative strategies.

Autoimmune Myocarditis, Old Dogs and New Tricks

Autoimmunity significantly contributes to the pathogenesis of myocarditis, underscored by its increased frequency in autoimmune diseases such as systemic lupus erythematosus and polymyositis. Even in cases of myocarditis caused by viral infections, dysregulated immune responses contribute to pathogenesis. However, whether triggered by existing autoimmune conditions or viral infections, the precise antigens and immunologic pathways driving myocarditis remain incompletely understood. The emergence of myocarditis associated with immune checkpoint inhibitor therapy, commonly used for treating cancer, has afforded an opportunity to understand autoimmune mechanisms in myocarditis, with autoreactive T cells specific for cardiac myosin playing a pivotal role. Despite their self-antigen recognition, cardiac myosin-specific T cells can be present in healthy individuals due to bypassing the thymic selection stage. In recent studies, novel modalities in suppressing the activity of pathogenic T cells including cardiac myosin-specific T cells have proven effective in treating autoimmune myocarditis. This review offers an overview of the current understanding of heart antigens, autoantibodies, and immune cells as the autoimmune mechanisms underlying various forms of myocarditis, along with the latest updates on clinical management and prospects for future research.

Acute myocarditis: an overview of pathogenesis, diagnosis and management

Acute myocarditis encompasses a diverse presentation of inflammatory cardiomyopathies with infectious and non-infectious triggers. The clinical presentation is heterogeneous, from subtle symptoms like mild chest pain to life-threatening fulminant heart failure requiring urgent advanced hemodynamic support. This review provides a comprehensive overview of the current state of knowledge regarding the pathogenesis, diagnostic approach, management strategies, and directions for future research in acute myocarditis. The pathogenesis of myocarditis involves interplay between the inciting factors and the subsequent host immune response. Infectious causes, especially cardiotropic viruses, are the most frequently identified precipitants. However, autoimmune processes independent of microbial triggers, as well as toxic myocardial injury from drugs, chemicals or metabolic derangements also contribute to the development of myocarditis through diverse mechanisms. Furthermore, medications like immune checkpoint inhibitor therapies are increasingly recognized as causes of myocarditis. Elucidating the nuances of viral, autoimmune, hypersensitivity, and toxic subtypes of myocarditis is key to guiding appropriate therapy. The heterogeneous clinical presentation coupled with non-specific symptoms creates diagnostic challenges. A multifaceted approach is required, incorporating clinical evaluation, electrocardiography, biomarkers, imaging studies, and endomyocardial biopsy. Cardiovascular magnetic resonance imaging has become pivotal for non-invasive assessment of myocardial inflammation and fibrosis. However, biopsy remains the gold standard for histological classification and definitively establishing the underlying etiology. Management relies on supportive care, while disease-specific therapies are limited. Although some patients recover well with conservative measures, severe or fulminant myocarditis necessitates aggressive interventions such as mechanical circulatory support devices and transplantation. While immunosuppression is beneficial in certain histological subtypes, clear evidence supporting antiviral or immunomodulatory therapies for the majority of acute viral myocarditis cases remains insufficient. Substantial knowledge gaps persist regarding validated diagnostic biomarkers, optimal imaging surveillance strategies, evidence-based medical therapies, and risk stratification schema. A deeper understanding of the immunopathological mechanisms, rigorous clinical trials of targeted therapies, and longitudinal outcome studies are imperative to advance management and improve the prognosis across the myocarditis spectrum.

CaMKIIδ, Stabilized by RNA N6-Methyladenosine Reader IGF2BP2, Boosts Coxsackievirus B3-Induced Myocardial Inflammation via Interacting with TIRAP

Calcium/calmodulin-dependent protein kinase II (CaMKII) has been demonstrated to be aberrantly activated in viral myocarditis (VMC), but the role of its subtype CaMKIIδ in VMC remains unclear.VMC mice and cardiomyocytes models were induced by Coxsackievirus B3 (CVB3) treatment. Mice that underwent sham surgery and saline-treated cardiomyocytes served as controls. Body weight, survival, left ventricular ejection fraction (LVEF), and fractional shortening (LVFS) were measured, and HE staining was performed to evaluate heart function in VMC mice model and sham control. Inflammation factors in serum or cell supernatant were detected by ELISA. Expressions of CaMKIIδ, Toll/interleukin-1 receptor domain containing adaptor protein (TIRAP), insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2), nuclear factor NF-kappaB (NF-κB) signals, and inflammation factors were examined by quantitative real time polymerase chain reaction (qRT-PCR) or western blot. CCK-8, EdU, and flow cytometry were used to evaluate cell behaviors. Co-immunoprecipitation (Co-IP), RNA immunoprecipitation (RIP), and RNA pull-down were utilized to validate molecule interaction. Methylated RNA immunoprecipitation (MeRIP) was performed to measure N6-methyladenosine (m6A) level of specific molecule.CaMKIIδ was upregulated in VMC mice and CVB3-treated primary cardiomyocytes, of which knockdown improved cell viability, proliferation, and suppressed cell apoptosis in vitro, thereby alleviating myocarditis in vivo. The stability of CaMKIIδ was attributed to the presence of IGF2BP2 through m6A modification. Loss of CaMKIIδ repressed NF-κB pathway via negatively and directly regulating TIRAP to be involved in inflammatory damage.CaMKIIδ, stabilized by m6A reader IGF2BP2, modulated NF-κB pathway via interacting with TIRAP to alter cell viability, proliferation, and apoptosis, thereby affecting VMC outcome.

Infectious factors in myocarditis: a comprehensive review of common and rare pathogens

BACKGROUND

Myocarditis is a significant health threat today, with infectious agents being the most common cause. Accurate diagnosis of the etiology of infectious myocarditis is crucial for effective treatment.

MAIN BODY

Infectious myocarditis can be caused by viruses, prokaryotes, parasites, and fungi. Viral infections are typically the primary cause. However, some rare opportunistic pathogens can also damage heart muscle cells in patients with immunodeficiencies, neoplasms and those who have undergone heart surgery.

CONCLUSIONS

This article reviews research on common and rare pathogens of infectious myocarditis, emphasizing the complexity of its etiology, with the aim of helping clinicians make an accurate diagnosis of infectious myocarditis.

Abundant Neutrophil-Initiated Acute Myocardial Injury Following Coxsackievirus A6 Infection

Coxsackievirus A6 (CVA6) is currently considered as a predominant pathogen of hand, foot, and mouth disease (HFMD), and is occasionally linked to myocardial injury. We first established a mouse model of CVA6-induced myocardial injury. Next, we analyzed the immune cell phenotypes CVA6-infected mice hearts by fluorescence-activated cell sorting, and found that CVA6 led to massive neutrophils infiltration, suggesting their potential link with the occurrence of myocardial injury. We further used either αGr-1 or αLy6G antibody to deplete neutrophils, and found that neutrophil-depleted animals showed decreased cardiac enzymes, lower degree of pathology in hearts, and reduced inflammatory cytokine production compared to isotype controls. Finally, we confirmed the involvement of neutrophils in myocardial injury of clinical patients with severe HFMD. Our study suggests that excessive neutrophils contribute to myocardial injury caused by CVA6 infection, which provides new insights into myocardial injury during the development of HFMD severity and the outcome of immune cell-mediated therapies.

Case Report: Three cases of clinically suspected viral myocarditis with recovery of left ventricular dysfunction

Viral myocarditis is an important cause of non-ischemic cardiomyopathy. Multiple clinical manifestations have been reported, including acute heart failure, cardiogenic shock, and ventricular arrhythmias. We present three patients with clinically suspected viral myocarditis causing acute heart failure. Serum coxsackievirus B antibodies were positive in all three patients. Each case resulted in significant clinical improvement with hemodynamic support and acute recovery of left ventricular ejection fraction. Despite an initial critical presentation concerning for cardiogenic shock, we highlight three cases of clinically suspected coxsackie myocarditis with an excellent short-term prognosis.

ISG15 blocks cardiac glycolysis and ensures sufficient mitochondrial energy production during Coxsackievirus B3 infection

AIMS

Virus infection triggers inflammation and, may impose nutrient shortage to the heart. Supported by type I interferon (IFN) signalling, cardiomyocytes counteract infection by various effector processes, with the IFN-stimulated gene of 15 kDa (ISG15) system being intensively regulated and protein modification with ISG15 protecting mice Coxsackievirus B3 (CVB3) infection. The underlying molecular aspects how the ISG15 system affects the functional properties of respective protein substrates in the heart are unknown.

METHODS AND RESULTS

Based on the protective properties due to protein ISGylation, we set out a study investigating CVB3-infected mice in depth and found cardiac atrophy with lower cardiac output in ISG15-/- mice. By mass spectrometry, we identified the protein targets of the ISG15 conjugation machinery in heart tissue and explored how ISGylation affects their function. The cardiac ISGylome showed a strong enrichment of ISGylation substrates within glycolytic metabolic processes. Two control enzymes of the glycolytic pathway, hexokinase 2 (HK2) and phosphofructokinase muscle form (PFK1), were identified as bona fide ISGylation targets during infection. In an integrative approach complemented with enzymatic functional testing and structural modelling, we demonstrate that protein ISGylation obstructs the activity of HK2 and PFK1. Seahorse-based investigation of glycolysis in cardiomyocytes revealed that, by conjugating proteins, the ISG15 system prevents the infection-/IFN-induced up-regulation of glycolysis. We complemented our analysis with proteomics-based advanced computational modelling of cardiac energy metabolism. Our calculations revealed an ISG15-dependent preservation of the metabolic capacity in cardiac tissue during CVB3 infection. Functional profiling of mitochondrial respiration in cardiomyocytes and mouse heart tissue by Seahorse technology showed an enhanced oxidative activity in cells with a competent ISG15 system.

CONCLUSION

Our study demonstrates that ISG15 controls critical nodes in cardiac metabolism. ISG15 reduces the glucose demand, supports higher ATP production capacity in the heart, despite nutrient shortage in infection, and counteracts cardiac atrophy and dysfunction.

Therapeutic potential of cannabidiol (CBD) in the treatment of cardiovascular diseases

INTRODUCTION

Cannabidiol (CBD) is the primary non-psychoactive chemical derived from Cannabis Sativa, and its growing popularity is due to its potential therapeutic properties while avoiding the psychotropic effects of other phytocannabinoids, such as tetrahydrocannabinol (THC). Numerous pre-clinical studies in cellular and animal models and human clinical trials have demonstrated a positive impact of CBD on physiological and pathological processes. Recently, the FDA approved its use for the treatment of seizures, and clinical trials to test the efficacy of CBD in myocarditis and pericarditis are ongoing.

AREAS COVERED

We herein reviewed the current literature on the reported effects of CBD in the cardiovascular system, highlighting the physiological effects and the outcomes of using CBD as a therapeutic tool in pathological conditions to address this significant global health concern.

EXPERT OPINION

The comprehensive examination of the literature emphasizes the potential of CBD as a therapeutic option for treating cardiovascular diseases through its anti-inflammatory, vasodilatory, anti-fibrotic, and antioxidant properties in different conditions such as diabetic cardiomyopathy, myocarditis, doxorubicin-induced cardiotoxicity, and ischemia-reperfusion injury.

Cardiovascular magnetic resonance in the identification of extra-cardiac causes of myocarditis: a case series

Background

Myocarditis is challenging to diagnose due to its varied presentations. Endomyocardial biopsy is the gold standard for diagnosis, but its invasive nature has led to alternative non-invasive modalities, notably cardiovascular magnetic resonance (CMR). Identifying the precise aetiology of myocarditis is crucial for effective treatment, yet extra-cardiac causes are often overlooked. In this paper, we spotlight the underexplored role of CMR in diagnosing extra-cardiac aetiologies, utilizing three insightful cases for illustration.

Case summary

The first case is a 31-year-old patient with myocarditis secondary to a pyogenic liver abscess, identified through CMR, who improved after abscess drainage. The second case involves a 54-year-old patient with myocarditis attributed to adult T-cell leukaemia-lymphoma, with the loco-regional thickening process identified thanks to CMR. This patient had an unfavourable disease progression due to the underlying malignancy. The third case concerns a 23-year-old patient suffering from myocarditis associated with pneumonia, again illustrated effectively through CMR imaging, who recovered after antibiotic treatment.

Discussion

These cases underline the overlooked potential of CMR in diagnosing extra-cardiac aetiologies of myocarditis, even though such causes are rare. Despite current guidelines recognizing the importance of identifying the aetiology of myocarditis, they do not explicitly address the role of CMR in diagnosing extra-cardiac aetiologies. This article, therefore, proposes that future guidelines could emphasize the utility of CMR in exploring these causes, potentially leading to more accurate diagnoses and improved patient outcomes. It also advocates for a comprehensive, multidisciplinary approach to myocarditis diagnosis, encouraging vigilance for potential loco-regional causes, and calls for further research in this area.

Multiorgan Dysfunction in a Patient With Adult-Onset Still's Disease Flare: A Case Report

Adult-onset Still's disease (AOSD) is a rare multisystem inflammatory disorder. A 71-year-old lady who was on treatment for AOSD presented with clinical evidence of heart failure and was subsequently found to have impaired renal and hepatic function. Following extensive workup including a liver biopsy, the cause of liver dysfunction was determined to be congestive hepatopathy, while renal dysfunction was presumed to stem from the low output state. The etiology of myocardial dysfunction, driving liver and kidney injury, was considered to be myocarditis from AOSD or global myocardial dysfunction from a systemic inflammatory state. Management involved pulse-dose glucocorticoids followed by taper and anakinra for AOSD, alongside goal-directed medical therapy for cardiac failure. At follow-up after a month, hepatic and renal function had fully recovered, whereas cardiac function remained compromised, evidenced by persistently depressed ejection fraction and global hypokinesia on a repeat echocardiogram. This report delineates a systematic approach to multiorgan dysfunction in a patient with a rare condition such as AOSD and reviews the reported causes of hepatic and cardiac involvement in AOSD.

RNA m5C methylation modification: a potential therapeutic target for SARS-CoV-2-associated myocarditis

The Corona Virus Disease (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has quickly spread worldwide and resulted in significant morbidity and mortality. Although most infections are mild, some patients can also develop severe and fatal myocarditis. In eukaryotic RNAs, 5-methylcytosine (m5C) is a common kind of post-transcriptional modification, which is involved in regulating various biological processes (such as RNA export, translation, and stability maintenance). With the rapid development of m5C modification detection technology, studies related to viral m5C modification are ever-increasing. These studies have revealed that m5C modification plays an important role in various stages of viral replication, including transcription and translation. According to recent studies, m5C methylation modification can regulate SARS-CoV-2 infection by modulating innate immune signaling pathways. However, the specific role of m5C modification in SARS-CoV-2-induced myocarditis remains unclear. Therefore, this review aims to provide insights into the molecular mechanisms of m5C methylation in SARS-CoV-2 infection. Moreover, the regulatory role of NSUN2 in viral infection and host innate immune response was also highlighted. This review may provide new directions for developing therapeutic strategies for SARS-CoV-2-associated myocarditis.

Elucidation for the pharmacological effects and mechanism of Shen Bai formula in treating myocardial injury based on energy metabolism and serum metabolomic approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Shen Bai formula (SBF) is a proven effective traditional Chinese medicine for treating viral myocarditis (VMC) sequelae in clinic, and myocardial injury is the pathological basis of VMC sequelae. However, the pharmacological action and mechanism of SBF have not been systematically elucidated.

AIM OF THE STUDY

In present research, the doxorubicin-induced myocardial injury rat model was used to evaluate the efficacy of SBF, and energy metabolism and metabolomics approaches were applied to elucidate the effects of SBF on myocardial injury.

MATERIALS AND METHODS

Through energy metabolism measurement system and UPLC-Q-TOF-MS/MS oriented blood metabolomics, directly reflected the therapeutic effect of SBF at a macro level, and identified biomarkers of myocardial injury in microcosmic, revealing its metabolomic mechanism.

RESULTS

Results showed that SBF significantly improved the electrocardiogram (ECG), heart rate (HR), extent of myocardial tissue lesion, and ratio of heart and spleen. In addition, the serum levels of AST, CK, LDH, α-HBDH, cTnI, BNP, and MDA decreased, whereas SOD and ATP activity and content increased. Moreover, SBF increased locomotor activity and basic daily metabolism in rats with myocardial injury, restoring their usual level of energy metabolism. A total of 45 potential metabolomic biomarkers were identified. Among them, 44 biomarkers were significantly recalled by SBF, including representative biomarkers arachidonic acid (AA), 12-HETE, prostaglandin J2 (PGJ2), 15-deoxy-Δ-12,14-PGJ2, 15-keto-PGE2, 15(S)-HPETE, 15(S)-HETE, 8,11,14-eicosatrienoic acid and 9(S)-HODE, which involved AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism.

CONCLUSION

We successfully replicated a myocardial injury rat model with the intraperitoneal injection of doxorubicin, and elucidated the mechanism of SBF in treating myocardial injury. This key mechanism may be achieved by targeting action on COX, Alox, CYP, and 15-PGDH to increase or decrease the level of myocardial injury biomarker, and then emphatically interven in AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism, and participate in regulating purine metabolism, sphingolipid metabolism, primary bile acid biosynthesis, and steroid hormone synthesis.

An Update on Myocarditis in Forensic Pathology

In forensic medicine, myocarditis is a complicated topic in the context of sudden death and medical malpractice. A good knowledge of the etiopathology, histopathology, and available literature are both indispensable and essential for the correct management and evaluation of the causal link. Some agents, which are rarely lethal for humans, are not necessarily related to death from myocarditis, even if an infection in other organs such as the gastrointestinal tract is documented. The diagnosis of the causes of death is often difficult and confusing. In some cases, the hypothetical diagnosis of myocarditis as the cause of death is formulated by deduction, causing error and misleading the correct temporal evaluation of pathological events. We reviewed the literature realizing that histomorphological data are scarce and often poorly documented. Only after COVID-19 have the histomorphological aspects of myocarditis been better documented. This is due to poor autopsy practice and poor accuracy in identifying the specific histotype of myocarditis with identification of the responsible agent. We believe that four points are essential for a better understanding and complete diagnosis of the disease: (1) clinical classification of myocarditis; (2) etiological classification of myocarditis; (3) pathophysiology of viral and bacterial infections with host response; and (4) histopathological diagnosis with precise identification of the histotype and pathogen. In the review we provide histological images from authoritative scientific references with the aim of providing useful information and food for thought to readers.

Blood transcriptome analysis uncovered COVID-19-myocarditis crosstalk

BACKGROUND

The condition of COVID-19-related myocarditis has emerged as a prominent contributor to COVID-19 mortality. As the epidemic persists, its incidence continues to rise. Despite ongoing efforts, the elucidation of COVID-19-related myocarditis underlying molecular mechanisms still requires further investigation.

METHODS

Hub genes for COVID-19-related myocarditis were screened by integrating gene expression profile analysis via differential expression in COVID-19 (GSE196822) and myocarditis (GSE148153 and GSE147517). After verification with independent datasets (GSE211979, GSE167028, GSE178491 and GSE215865), the hub genes were studied using a range of systems-biology approaches, such as ceRNA, TF-mRNA networks and PPI networks, as well as gene ontology, pathway enrichment, immune infiltration analysis and drug target identification.

RESULTS

TBKBP1 and ERGIC1 were identified as COVID-19-related myocarditis hub genes via integrated bioinformatics analysis. In addition, receiver operating characteristic curves constructed based on the expression levels of TBKBP1 and ERGIC1 could effectively distinguish healthy control individuals from patients with COVID-19. Functional enrichment analysis suggested several enriched biological pathways related to inflammation and immune response. Immune cell changes correlated with TBKBP1 and ERGIC1 levels in patients with COVID-19 or patients with COVID-19 and myocarditis. Tamibarotene, methotrexate and theophylline were identified as a potential drug targeting TBKBP1 and ERGIC1.

CONCLUSION

TBKBP1 and ERGIC1 were identified as crucial genes in the development of COVID-19-related myocarditis and have demonstrated a strong association with innate antiviral immunity. The present work may be helpful for further investigation of the molecular mechanisms and new therapeutic drug targets correlated with myocarditis in COVID-19.

Fatal ventricular arrhythmias in myocarditis: A review of current indications for defibrillator devices

Historically, patients with myocarditis were considered for implantable cardioverter defibrillator (ICD) utilization only in the chronic phase of the disease following the development of persistent cardiomyopathy refractory to medical therapy or occurrence of a major ventricular arrhythmic event. However, recent literature has indicated that ventricular arrhythmias are frequently reported even in the acute phase of the disease, challenging the long-standing perception that this disease process was largely reversible. Given this changing environment of information, the latest US and European guidelines were recently updated in 2022 to now consider ICD implantation during the acute phase which has significantly increased the number of individuals eligible for these devices. Additionally, several studies with small subgroups of patients have demonstrated a possible benefit of wearable cardioverter defibrillators (WCDs) in this patient demographic. Assuming that larger studies confirm their utility, it is possible that WCDs can assist in detection of ventricular arrhythmias and selection of high-risk candidates for ICD implantation, while providing temporary protection for a small percentage of patients before the development of a major arrhythmic event. This review ultimately serves as a comprehensive review of the most recent guidelines for defibrillator use in acute and chronic myocarditis. OPINION STATEMENT: The latest US and European guidelines support ICD use for myocarditis patients following the development of persistent cardiomyopathy refractory to medical therapy or occurrence of a major ventricular arrhythmic event. Previously, patients in the acute phase were excluded from ICD utilization even after experiencing malignant ventricular tachycardia or ventricular fibrillation due to the long-standing perception that this disease process was largely reversible. However, recent literature has indicated that ventricular arrhythmias are frequently reported even in the acute phase of the disease. Additionally, we found that the myocardial damage that is inflicted persists many years after the initial episode. Given this changing environment of information, guidelines were recently updated in 2022 to now consider ICD implantation during the acute phase which has significantly increased the number of individuals eligible for these devices. We support possible ICD utilization for secondary prevention during the acute phase of myocarditis given the elevated risk of arrhythmia recurrence and the fact that any ventricular arrhythmia can induce sudden cardiac death. Future prospective studies are needed to assess which patients may benefit most from early ICD implantation. WCDs have improved survival in patient populations at high-risk for sudden cardiac death who are not candidates for ICD implantation. After analyzing several recent studies with small subgroups of patients, WCDs appear to demonstrate similar efficacy for myocarditis patients as well. Assuming that larger studies confirm their utility, we believe that WCDs can assist in detection of ventricular arrhythmias and selection of high-risk candidates for ICD implantation. Furthermore, WCDs have the additional benefit of acting as primary prevention by providing temporary protection for a small percentage of myocarditis patients before they develop a major arrhythmic event.

The role of deubiquitinases in cardiac disease

Deubiquitinases are a group of proteins that identify and digest monoubiquitin chains or polyubiquitin chains attached to substrate proteins, preventing the substrate protein from being degraded by the ubiquitin-proteasome system. Deubiquitinases regulate cellular autophagy, metabolism and oxidative stress by acting on different substrate proteins. Recent studies have revealed that deubiquitinases act as a critical regulator in various cardiac diseases, and control the onset and progression of cardiac disease through a board range of mechanism. This review summarizes the function of different deubiquitinases in cardiac disease, including cardiac hypertrophy, myocardial infarction and diabetes mellitus-related cardiac disease. Besides, this review briefly recapitulates the role of deubiquitinases modulators in cardiac disease, providing the potential therapeutic targets in the future.

Integration of transcriptomics and metabolomics reveals toxicological mechanisms of ZhuRiHeng drop pill in the 180-day repeated oral toxicity study

Background: ZhuRiHeng Drop Pill (ZRH) is a traditional Mongolian medicinal preparation. Despite its long history of use for the treatment of coronary heart disease, there have been few toxicological studies of the safety profile of ZRH. Purpose: In order to comprehensively elucidate the underlying mechanisms behind the observed toxicity of ZRH on rat livers in the 180-day repeated oral toxicity study, we conducted a comprehensive analysis by integrating transcriptomic and metabolomic data. Methods: High-resolution mass spectrometry was conducted to evaluate the constituents of ZRH. For the acute oral toxicity study, mice were administered a dose of 32 g/(kg·d) of ZRH, while rats were instead orally administered 0.934, 1.868, or 3.736 g/(kg·d) of ZRH over a 180-day period in a 180-day repeated oral toxicity study. Conventional index and organ weights/histology were then monitored to detect any potential ZRH treatment-related toxicity. To identify key genes and metabolites involved in ZRH toxicological processes, we performed transcriptomic and metabolomic analyses of liver tissue upon ZRH treatment using RNA-seq techniques, qPCR and liquid chromatography-mass spectrometry analyses. Results: A total of 60 compounds in ZRH were identified and speculated in positive and negative ion modes. Mice in the acute toxicity study exhibited no signs of ZRH-related toxicity. In a protracted oral toxicity investigation spanning 180 days, discernible elevations in liver ratios were noted in both male and female rats across all three dose cohorts, relative to the control group (p < 0.05 or p < 0.01). Upon subjecting to ZRH treatment, our transcriptomic and qPCR analyses unveiled notable upregulation of crucial genes, exemplified by Abcb1b and Cyp2b2, known for theirs involvement in liver drug transport and metabolism function. Furthermore, our untargeted metabolomic analysis provided supplementary insights, revealing significant regulation in pyrimidine metabolism, as well as alanine, aspartate, and glutamate metabolism pathways. Conclusion: Our study unveils a panoramic understanding of the temporal, dosage-specific, and gene dimensions surrounding the metabolic and transcriptional shifts induced by ZRH exposure. As we peer into the future, recommendations emerge for further exploration, encompassing aspects such as time dynamics, dosage considerations, and gene-centric avenues to enhance therapeutic efficacy.

Paradigm shift in myocarditis treatment

Although most cases of myocarditis are self-limiting with a gradual improvement in cardiac function, the involvement of myocarditis in sudden cardiac death among children and young adults remains substantial, with rates of 3-17 % and 8.6-12 %, respectively. Moreover, the risk of developing chronic dilated cardiomyopathy ranges from 21 % to 30 % in all cases confirmed by biopsy. Current therapeutic strategies for myocarditis and its complications range from standard supportive care for heart failure and arrhythmias to etiologically oriented, case-based therapeutic options. For example, immunosuppression is indicated only in certain forms of acute myocarditis with clinical or endomyocardial biopsy evidence of immune checkpoint inhibitor-induced myocarditis and autoimmune diseases, including giant cell myocarditis, eosinophilic myocarditis, vasculitis, or cardiac sarcoidosis. However, our views on myocarditis treatment have changed considerably over the past two decades, thanks to the emergence of regenerative cells/tissues as well as drug and gene delivery systems. Cell-based therapies are now growing in popularity in any field of medicine. Studies evaluating the therapeutic efficacy of different stem cells in the treatment of acute myocarditis and its chronic complications have shown that although the experimental characteristics varied from study to study, in general, these strategies reduced inflammation and myocardial fibrosis while preventing myocarditis-induced systolic dysfunction and adverse remodeling in animal models.

Approach to Imaging of Patients Presenting With Acute Coronary Syndrome With No Culprit Lesion Identified at Angiography

Chest pain is a common chief complaint among patients presenting to the emergency department. However, in the scenario where the clinical presentation is consistent with acute coronary syndrome and no culprit lesions are identified on angiography, clinicians and cardiac imagers should be informed of the differential diagnosis and appropriate imaging modalities used to investigate the potential causes. This review describes an imaging-based algorithm that highlights the diagnostic possibilities, their differentiating imaging features, and the important role of cardiovascular magnetic resonance imaging for narrowing the differential diagnosis.

Multidisciplinary approach in cardiomyopathies: From genetics to advanced imaging

Cardiomyopathies are myocardial diseases characterized by mechanical and electrical dysfunction of the heart muscle which could lead to heart failure and life-threatening arrhythmias. Certainly, an accurate anamnesis, a meticulous physical examination, and an ECG are cornerstones in raising the diagnostic suspicion. However, cardiovascular imaging techniques are indispensable to diagnose a specific cardiomyopathy, to stratify the risk related to the disease and even to track the response to the therapy. Echocardiography is often the first exam that the patient undergoes, because of its non-invasiveness, wide availability, and cost-effectiveness. Cardiac magnetic resonance imaging allows to integrate and implement the information obtained with the echography. Furthermore, cardiomyopathies' genetic basis has been investigated over the years and the list of genetic mutations deemed potentially pathogenic is expected to grow further. The aim of this review is to show echocardiographic, cardiac magnetic resonance imaging, and genetic features of several cardiomyopathies: dilated cardiomyopathy (DMC), hypertrophic cardiomyopathy (HCM), arrhythmogenic cardiomyopathy (ACM), left ventricular noncompaction cardiomyopathy (LVNC), myocarditis, and takotsubo cardiomyopathy.

Mechanical Circulatory Support Systems in Fulminant Myocarditis: Recent Advances and Outlook

Background: Fulminant myocarditis (FM) constitutes a severe and life-threatening form of acute cardiac injury associated with cardiogenic shock. The condition is characterised by rapidly progressing myocardial inflammation, leading to significant impairment of cardiac function. Due to the acute and severe nature of the disease, affected patients require urgent medical attention to mitigate adverse outcomes. Besides symptom-oriented treatment in specialised intensive care units (ICUs), the necessity for temporary mechanical cardiac support (MCS) may arise. Numerous patients depend on these treatment methods as a bridge to recovery or heart transplantation, while, in certain situations, permanent MCS systems can also be utilised as a long-term treatment option. Methods: This review consolidates the existing evidence concerning the currently available MCS options. Notably, data on venoarterial extracorporeal membrane oxygenation (VA-ECMO), microaxial flow pump, and ventricular assist device (VAD) implantation are highlighted within the landscape of FM. Results: Indications for the use of MCS, strategies for ventricular unloading, and suggested weaning approaches are assessed and systematically reviewed. Conclusions: Besides general recommendations, emphasis is put on the differences in underlying pathomechanisms in FM. Focusing on specific aetiologies, such as lymphocytic-, giant cell-, eosinophilic-, and COVID-19-associated myocarditis, this review delineates the indications and efficacy of MCS strategies in this context.

A Narrative Review of Preclinical In Vitro Studies Investigating microRNAs in Myocarditis

According to the World Health Organization's statement, myocarditis is an inflammatory myocardium disease. Although an endometrial biopsy remains the diagnostic gold standard, it is an invasive procedure, and thus, cardiac magnetic resonance imaging has become more widely used and is called a non-invasive diagnostic gold standard. Myocarditis treatment is challenging, with primarily symptomatic therapies. An increasing number of studies are searching for novel diagnostic biomarkers and potential therapeutic targets. Microribonucleic acids (miRNAs) are small, non-coding RNA molecules that decrease gene expression by inhibiting the translation or promoting the degradation of complementary mRNAs. Their role in different fields of medicine has been recently extensively studied. This review discusses all relevant preclinical in vitro studies regarding microRNAs in myocarditis. We searched the PubMed database, and after excluding unsuitable studies and clinical and preclinical in vivo trials, we included and discussed 22 preclinical in vitro studies in this narrative review. Several microRNAs presented altered levels in myocarditis patients in comparison to healthy controls. Moreover, microRNAs influenced inflammation, cell apoptosis, and viral replication. Finally, microRNAs were also found to determine the level of myocardial damage. Further studies may show the vital role of microRNAs as novel therapeutic agents or diagnostic/prognostic biomarkers in myocarditis management.

Sex differences in myocarditis hospitalizations: Rates, outcomes, and hospital characteristics in the National Readmission Database

Inflammation of the myocardium, or myocarditis, presents with varied severity, from mild to life-threatening such as cardiogenic shock or ventricular tachycardia storm. Existing data on sex-related differences in its presentation and outcomes are scarce. Using the Nationwide Readmission Database (2016-2019), we identified myocarditis hospitalizations and stratified them according to sex to either males or females. Multivariable regression analyses were used to determine the association between sex and myocarditis outcomes. The primary outcome was in-hospital mortality, and the secondary outcomes included sudden cardiac death (SCD), cardiogenic shock (CS), use of mechanical circulatory support (MCS), and 90-day readmissions. We found a total of 12,997 myocarditis hospitalizations, among which 4,884 (37.6 %) were females. Compared to males, females were older (51 ± 15.6 years vs. 41.9 ± 14.8 in males) and more likely to have connective tissue disease, obesity, and a history of coronary artery disease. No differences were noted between the two groups with regards to in-hospital mortality (adjusted odds ratio [aOR] 1.20; confidence interval [CI] 0.93-1.53; P = 0.16), SCD (aOR:1.18; CI 0.84-1.64; P = 0.34), CS (aOR: 1.01; CI 0.85-1.20;P = 0.87), or use of MCS (aOR: 1.07; CI:0.86-1.34; P = 0.56). In terms of interventional procedures, females had lower rates of coronary angiography (aOR: 0.78; CI 0.70-0.88; P < 0.01), however, similar rates of right heart catheterization (aOR 0.93; CI:0.79-1.09; P = 0.36) and myocardial biopsy (aOR: 1.16; CI:0.83-1.62; P = 0.38) compared to males. Additionally, females had a higher risk of 90-day all-cause readmission (aOR: 1.25; CI: 1.16-1.56; P < 0.01) and myocarditis readmission (aOR:1.58; CI 1.02-2.44; P = 0.04). Specific predictors of readmission included essential hypertension, congestive heart failure, malignancy, and peripheral vascular disease. In conclusion, females admitted with myocarditis tend to have similar in-hospital outcomes with males; however, they are at higher risk of readmission within 90 days from hospitalization. Further studies are needed to identify those at higher risk of readmission.

Myocarditis: A multi-omics approach

Myocarditis, an inflammatory condition of weakened heart muscles often triggered by a variety of causes, that can result in heart failure and sudden death. Novel ways to enhance our understanding of myocarditis pathogenesis is available through newer modalities (omics). In this review, we examine the roles of various biomolecules and associated functional pathways across genomics, transcriptomics, proteomics, and metabolomics in the pathogenesis of myocarditis. Our analysis further explores the reproducibility and variability intrinsic to omics studies, underscoring the necessity and significance of employing a multi-omics approach to gain profound insights into myocarditis pathogenesis. This integrated strategy not only enhances our understanding of the disease, but also confirms the critical importance of a holistic multi-omics approach in disease analysis.

Multitargeted Immunomodulatory Therapy for Viral Myocarditis by Engineered Extracellular Vesicles

Immune regulation therapies are considered promising for treating classically activated macrophage (M1)-driven viral myocarditis (VM). Alternatively, activated macrophage (M2)-derived extracellular vesicles (M2 EVs) have great immunomodulatory potential owing to their ability to reprogram macrophages, but their therapeutic efficacy is hampered by insufficient targeting capacity in vivo. Therefore, we developed cardiac-targeting peptide (CTP) and platelet membrane (PM)-engineered M2 EVs enriched with viral macrophage inflammatory protein-II (vMIP-II), termed CTP/PM-M2 EVsvMIP-II-Lamp2b, to improve the delivery of EVs "cargo" to the heart tissues. In a mouse model of VM, the intravenously injected CTP/PM-M2 EVsvMIP-II-Lamp2b could be carried into the myocardium via CTP, PM, and vMIP-II. In the inflammatory microenvironment, macrophages differentiated from circulating monocytes and macrophages residing in the heart showed enhanced endocytosis rates for CTP/PM-M2 EVsvMIP-II-Lamp2b. Subsequently, CTP/PM-M2 EVsvMIP-II-Lamp2b successfully released functional M2 EVsvMIP-II-Lamp2b into the cytosol, which facilitated the reprogramming of inflammatory M1 macrophages to reparative M2 macrophages. vMIP-II not only helps to increase the targeting ability of M2 EVs but also collaborates with M2 EVs to regulate M1 macrophages in the inflammatory microenvironment and downregulate the levels of multiple chemokine receptors. Finally, the cardiac immune microenvironment was protectively regulated to achieve cardiac repair. Taken together, our findings suggest that CTP-and-PM-engineered M2 EVsvMIP-II-Lamp2b represent an effective means for treating VM and show promise for clinical applications.

Determinants of COVID-19 vaccine-induced myocarditis

Background

Following the roll-out of the Pfizer-BioNTech BNT162b2, Moderna mRNA-1273, and Janssen Ad26.COV2.S coronavirus disease 2019 (COVID-19) injections in the United States, millions of individuals have reported adverse events (AEs) using the vaccine adverse events reports system (VAERS). The objective of this analysis is to describe the myocarditis data in VAERS and the COVID-19 vaccines as potential determinants of myocarditis.

Methods

We used VAERS data to examine the frequency of reporting myocarditis since the beginning of the mass vaccination campaign and compared this with historical values in VAERS and COVID-19 vaccine administration data from the Our World in Data database. We examined myocarditis reports in VAERS in the context of sex, age, and dose. Statistical analysis was done using the Student's t-test to determine statistically significant differences between ages among myocarditis adverse events (AEs) and the chi-square test to determine relationships between categorical variables with statistical significance.

Results

We found the number of myocarditis reports in VAERS after COVID-19 vaccination in 2021 was 223 times higher than the average of all vaccines combined for the past 30 years. This represented a 2500% increase in the absolute number of reports in the first year of the campaign when comparing historical values prior to 2021. Demographic data revealed that myocarditis occurred most in youths (50%) and males (69%). A total of 76% of cases resulted in emergency care and hospitalization. Of the total myocarditis reports, 92 individuals died (3%). Myocarditis was more likely after dose 2 (p < 0.00001) and individuals less than 30 years of age were more likely than individuals older than 30 to acquire myocarditis (p < 0.00001).

Conclusion

COVID-19 vaccination is strongly associated with a serious adverse safety signal of myocarditis, particularly in children and young adults resulting in hospitalization and death. Further investigation into the underlying mechanisms of COVID-19 vaccine-induced myocarditis is imperative to create effective mitigation strategies and ensure the safety of COVID-19 vaccination programs across populations.

Role of immune cells in the pathogenesis of myocarditis

Myocarditis is an inflammatory heart disease that mostly affects young people. Myocarditis involves a complex immune network; however, its detailed pathogenesis is currently unclear. The diversity and plasticity of immune cells, either in the peripheral blood or in the heart, have been partially revealed in a number of previous studies involving patients and several kinds of animal models with myocarditis. It is the complexity of immune cells, rather than one cell type that is the culprit. Thus, recognizing the individual intricacies within immune cells in the context of myocarditis pathogenesis and finding the key intersection of the immune network may help in the diagnosis and treatment of this condition. With the vast amount of cell data gained on myocarditis and the recent application of single-cell sequencing, we summarize the multiple functions of currently recognized key immune cells in the pathogenesis of myocarditis to provide an immune background for subsequent investigations.

Targeting the Translocator Protein (18 kDa) in Cardiac Diseases: State of the Art and Future Opportunities

Mitochondria dysfunctions are typical hallmarks of cardiac disorders (CDs). The multiple tasks of this energy-producing organelle are well documented, but its pathophysiologic involvement in several manifestations of heart diseases, such as altered electromechanical coupling, excitability, and arrhythmias, is still under investigation. The human 18 kDa translocator protein (TSPO) is a protein located on the outer mitochondrial membrane whose expression is altered in different pathological conditions, including CDs, making it an attractive therapeutic and diagnostic target. Currently, only a few TSPO ligands are employed in CDs and cardiac imaging. In this Perspective, we report an overview of the emerging role of TSPO at the heart level, focusing on the recent literature concerning the development of TSPO ligands used for fighting and imaging heart-related disease conditions. Accordingly, targeting TSPO might represent a successful strategy to achieve novel therapeutic and diagnostic strategies to unravel the fundamental mechanisms and to provide solutions to still unanswered questions in CDs.

Functions and Clinical Significance of Myocardial Cell-Derived Immunoglobulins

Immunoglobulins (Igs) have been widely accepted to be exclusively expressed by B cells. Nonetheless, this theory is challenged by mounting evidence which suggests that Igs can also be generated by non B cells (non B-Ig), including cardiomyocytes (CM). Non B-Ig exhibits unique physical and chemical characteristics, unique variable region sequences and functions, which diverge from those of B-Ig. For instance, non B-Ig demonstrates hydrophobicity, limited diversity in the variable region, and extracellular matrix protein activity. Likewise, cardiomyocytes can express different classes of Igs, including IgM, IgG, and free Igκ light chains (cardiomyocyte derived-Igs, CM-Igs). In particular, CM-Igs can be secreted into the extracellular space in various cardiovascular diseases, such as myocardial ischaemia and myocardial fibrosis where they might be involved in complement activation and direct damage to cardiomyocytes. Nevertheless, the precise pathological activity of CM-Igs remains unclear. Recently, Zhu et al. focused on studying the sequence characteristics and functions of CM-Igκ; they discovered that the CM-Igκ exhibits a unique VJ recombination pattern, high hydrophobicity, and is principally located on the intercalated discs and cross striations of the cardiomyocytes. Interestingly, loss of Igκ in cardiomyocytes results in structural disorders in intercalated discs and dysfunction in myocardial contraction and conduction. Mechanically, Igκ promotes the stabilisation of plectin, a cytoskeleton cross-linker protein that connects desmin to desomsome, to maintain the normal structure of the intercalated disc. This finding indicates that CM-Igκ plays an integral role in maintaining cytoskeleton structure. Consequently, it is imperative to reveal the physiological functions and mechanisms of pathological injury associated with CM-Igs.

Transcriptional and functional analysis of plasma exosomal microRNAs in acute viral myocarditis

AIM

To assess the differential expression profiles of exosome-derived microRNA (miRNA) and reveal their potential functions in patients with acute viral myocarditis (AVMC).

MATERIALS & METHODS

Peripheral blood samples were collected from 9 patients diagnosed with AVMC and 9 healthy controls (HC) in the Affiliated Hospital of Qingdao University from July 2021 to September 2022. The exosomal miRNA expression were tested using RNA high-throughput sequencing. We conducted the GO and KEGG functional analysis to predict the potential molecular, biological functions and related signaling pathways of miRNAs in exosomes. Target genes of exosomal miRNAs were predicted and miRNA-target gene network was mapped using gene databases. Differentially expressed exosomal miRNAs were selected and their expression levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR) to verify the sequencing results.

RESULTS

P < 0.05 and Fold Change>2 were considered as cut-off value to screen miRNAs that were differently expressed. This study identified 14 upregulated and 14 downregulated exosome-derived miRNAs. GO and KEGG analysis showed that differentially expressed miRNAs may be related to β-catenin binding, DNA transcription activities, ubiquitin ligase, PI3K-Akt, FoxO, P53, MAPK, and etc.. The target genes of differentially expressed miRNAs were predicted using gene databases. Real-time PCR confirmed the upregulation of hsa-miR-548a-3p and downregulation of hsa-miR-500b-5p in AVMC.

CONCLUSIONS

Hsa-miR-548a-3p and hsa-miR-500b-5p could serve as a promising biomarker of AVMC. Exosomal miRNAs may have substantial roles in the mechanisms of AVMC.

Fulminant myocarditis proven by early biopsy and outcomes

BACKGROUND AND AIMS

While endomyocardial biopsy (EMB) is recommended in adult patients with fulminant myocarditis, the clinical impact of its timing is still unclear.

METHODS

Data were collected from 419 adult patients with clinically suspected fulminant myocarditis admitted to intensive care units across 36 tertiary centres in 15 countries worldwide. The diagnosis of myocarditis was histologically proven in 210 (50%) patients, either by EMB (n = 183, 44%) or by autopsy/explanted heart examination (n = 27, 6%), and clinically suspected cardiac magnetic resonance imaging confirmed in 96 (23%) patients. The primary outcome of survival free of heart transplantation (HTx) or left ventricular assist device (LVAD) at 1 year was specifically compared between patients with early EMB (within 2 days after intensive care unit admission, n = 103) and delayed EMB (n = 80). A propensity score-weighted analysis was done to control for confounders.

RESULTS

Median age on admission was 40 (29-52) years, and 322 (77%) patients received temporary mechanical circulatory support. A total of 273 (65%) patients survived without HTx/LVAD. The primary outcome was significantly different between patients with early and delayed EMB (70% vs. 49%, P = .004). After propensity score weighting, the early EMB group still significantly differed from the delayed EMB group in terms of survival free of HTx/LVAD (63% vs. 40%, P = .021). Moreover, early EMB was independently associated with a lower rate of death or HTx/LVAD at 1 year (odds ratio of 0.44; 95% confidence interval: 0.22-0.86; P = .016).

CONCLUSIONS

Endomyocardial biopsy should be broadly and promptly used in patients admitted to the intensive care unit for clinically suspected fulminant myocarditis.

Causal relationship between COVID-19 and myocarditis or pericarditis risk: a bidirectional Mendelian randomization study

Background & aims

Coronavirus disease 2019 (COVID-19) is strongly associated with myocarditis or pericarditis risk in observational studies, however, there are still studies that do not support the above conclusion. Whether the observed association reflects causation needs to be confirmed. We performed a bidirectional Mendelian randomization (MR) study to assess the causal relationship of COVID-19, which was divided into three groups, namely severe COVID-19, hospitalized COVID-19, and COVID-19 infection, measured by myocarditis or pericarditis.

Methods

We extracted summary genome-wide association statistics for the severe COVID-19 (case: 13,769, control: 1,072,442), hospitalized COVID-19 (case: 32,519, control: 2,062,805), COVID-19 infection (case: 122,616, control: 2,475,240), myocarditis (case 1,521, control 191,924), and pericarditis (case 979, control 286,109) among individuals of European ancestry. Independent genetic variants that exhibited a significant association with each phenotype at the genome-wide level of significance were utilized as instrumental variables. Estimation of the causal effect was mainly performed using the random effects inverse-variance weighted method (IVW). Additionally, other tests such as MR-Egger intercept, MR-PRESSO, Cochran's Q-test, "Leave-one-out", and funnel plots were conducted to assess the extent of pleiotropy and heterogeneity.

Results

Non-associations in the IVW and sensitivity analyses were observed for COVID-19 with myocarditis or pericarditis. Severe COVID-19 was not associated with myocarditis [odds ratio (OR), 1.00; 95% confidence interval (CI), 0.89-1.12; P = 0.99], pericarditis (OR = 0.90, 95% CI, 0.78-1.04, P = 0.17). Similar results can be observed in hospitalized COVID-19, and COVID-19 infection. At the same time, null associations were observed for myocarditis or pericarditis with COVID-19 traits in the reverse direction. The main results are kept stable in the sensitivity analysis.

Conclusion

There is no evidence that COVID-19 is independently and causally associated with myocarditis or pericarditis.

A novel case of acute glomerulonephritis with concurrent acute non-rheumatic myocarditis following group a streptococcal infection

Streptococcal infection is a common cause of acute glomerulonephritis. Cardiac damage associated with streptococcal infection commonly occurs in acute rheumatic fever. However, cases of acute non-rheumatic streptococcal myocarditis have been reported in recent years. We report a novel case of concurrent acute glomerulonephritis and non-rheumatic myocarditis following streptococcal infection. A good prognosis was achieved with antibiotic and immunosuppressive therapy, indicating that Streptococcus causes cardiorenal syndrome type 5 via an immune-mediated response. A better understanding of post-streptococcal cardiorenal syndrome is warranted to enable the early diagnosis and treatment of affected patients.

Mechanisms and therapeutic strategies of extracellular vesicles in cardiovascular diseases

Cardiovascular disease (CVD) significantly impacts global society since it is the leading cause of death and disability worldwide, and extracellular vesicle (EV)-based therapies have been extensively investigated. EV delivery is involved in mediating the progression of CVDs and has great potential to be biomarker and therapeutic molecular carrier. Besides, EVs from stem cells and cardiac cells can effectively protect the heart from various pathologic conditions, and then serve as an alternative treatment for CVDs. Moreover, the research of using EVs as delivery carriers of therapeutic molecules, membrane engineering modification of EVs, or combining EVs with biomaterials further improves the application potential of EVs in clinical treatment. However, currently there are only a few articles summarizing the application of EVs in CVDs. This review provides an overview of the role of EVs in the pathogenesis and diagnosis of CVDs. It also focuses on how EVs promote the repair of myocardial injury and therapeutic methods of CVDs. In conclusion, it is of great significance to review the research on the application of EVs in the treatment of CVDs, which lays a foundation for further exploration of the role of EVs, and clarifies the prospect of EVs in the treatment of myocardial injury.

Thalidomide and a Dipeptidyl Peptidase 4 Inhibitor in a Rat Model of Experimental Autoimmune Myocarditis

BACKGROUND AND OBJECTIVES

Myocarditis is a potentially fatal disease, but curative treatments have not yet been established. Myocardial inflammation is an important pathogenesis of this disease, and immunosuppressants such as methylprednisolone and immunoglobulin have been used for treatment; however, the effectiveness needs to be improved. Thalidomide and dipeptidyl peptidase (DPP) 4 inhibitors were recently investigated regarding their immunomodulatory properties. This study aimed to test whether thalidomide or a DPP4 inhibitor (evogliptin) can improve the effectiveness of myocarditis treatment using a rat model of experimental autoimmune myocarditis (EAM).

METHODS

Rats with or without myocarditis were administered thalidomide at 100 mg/kg/day and DPP4 inhibitor at 10 mg/kg/day orally. Measurement of echocardiography, serum inflammatory cytokines, myocardial histopathological examination, and immunohistochemical staining for leukocytes, macrophages, CD4+ T cells, and cytoskeleton were performed after 3 weeks, and the fibrosis area was measured after 3 and 6 weeks.

RESULTS

Thalidomide and DPP4 inhibitor did not reduce the severity of myocarditis compared with the EAM without treatment rats by comparing the echocardiographic data, myocardial CD4+, macrophages, neutrophil infiltrations, and the heart weight/body weight ratio in 3 weeks. The levels of inflammatory cytokines were not lower in the thalidomide and DPP4 inhibitor-treated group than in the untreated group in 3 weeks. In 6 weeks, thalidomide and DPP4 inhibitors did not reduce the fibrosis area compared to untreated groups.

CONCLUSIONS

Although thalidomide and the DPP4 inhibitor had an immunomodulatory effect and are used against inflammatory diseases, they did not ameliorate myocardial inflammation and fibrosis in this rat model of EAM.

Characterization of Subclinical Cardiac Dysfunction by Speckle Tracking Echocardiography in Patients With Non-severe Acute-Phase Myocarditis

Subclinical changes in left ventricular (LV) function have been demonstrated in patients with acute-phase myocarditis (AM) despite normal LV ejection fraction. The impact of AM on right ventricular (RV) and left atrial (LA) function has not been well described. This study aimed to assess for subclinical chamber dysfunction by speckle tracking echocardiography and its clinical relevance in this population. Patients with a diagnosis of AM (as per the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases) admitted to our institution from 2013 to 2018 were assessed. Patients with elevated serum troponin, normal coronary assessment, and normal LV ejection fraction on transthoracic echocardiogram were included. Clinical and echocardiographic parameters were compared with healthy age-, gender- and risk-factor matched controls. Global longitudinal strain assessed through speckle tracking echocardiography was performed using vendor independent software (v4.6; TomTec Arena, Munich, Germany). The final cohort consisted of 80 patients (40 AM patients and 40 controls). No significant differences in baseline clinical characteristics were observed between groups. Of the echocardiographic parameters, AM patients had lower LV-global longitudinal strain (p <0.01), lower RV free-wall strain (p = 0.02) and lower peak LA strain (p <0.01). There were no differences in traditional echocardiographic measures of LV, RV, and LA function appreciated between groups. The presence of multichamber involvement was associated with peak Troponin levels (p <0.01). In conclusion, our study demonstrates the presence of global subclinical myocardial dysfunction in patients with AM. Additionally, the presence of multichamber involvement was significantly associated with degree of myocardial necrosis.

Myocardial Mitochondrial DNA Drives Macrophage Inflammatory Response through STING Signaling in Coxsackievirus B3-Induced Viral Myocarditis

Coxsackievirus B3 (CVB3), a single-stranded positive RNA virus, primarily infects cardiac myocytes and is a major causative pathogen for viral myocarditis (VMC), driving cardiac inflammation and organ dysfunction. However, whether and how myocardial damage is involved in CVB3-induced VMC remains unclear. Herein, we demonstrate that the CVB3 infection of cardiac myocytes results in the release of mitochondrial DNA (mtDNA), which functions as an important driver of cardiac macrophage inflammation through the stimulator of interferon genes (STING) dependent mechanism. More specifically, the CVB3 infection of cardiac myocytes promotes the accumulation of extracellular mtDNA. Such myocardial mtDNA is indispensable for CVB3-infected myocytes in that it induces a macrophage inflammatory response. Mechanistically, a CVB3 infection upregulates the expression of the classical DNA sensor STING, which is predominantly localized within cardiac macrophages in VMC murine models. Myocardial mtDNA efficiently triggers STING signaling in those macrophages, resulting in strong NF-kB activation when inducing the inflammatory response. Accordingly, STING-deficient mice are able to resist CVB3-induced cardiac inflammation, exhibiting minimal inflammation with regard to their functional cardiac capacities, and they exhibit higher survival rates. Moreover, our findings pinpoint myocardial mtDNA as a central element driving the cardiac inflammation of CVB3-induced VMC, and we consider the DNA sensor, STING, to be a promising therapeutic target for protecting against RNA viral infections.

Role for advanced heart failure therapies in the management of influenza B-associated fulminant myocarditis with recovery

A woman presented to the emergency department for syncope after developing influenza-like symptoms. She tested positive for influenza B. The patient rapidly decompensated into cardiogenic shock over 2 days, requiring aggressive pharmacological therapy and temporary mechanical circulatory support. She made a full recovery. This case highlights the importance of early intervention, urgent transplant evaluation and guideline directed medical therapy in the treatment of fulminant myocarditis secondary to influenza B infection.

ET-1 receptor type B (ETBR) overexpression associated with ICAM-1 downregulation leads to inflammatory attenuation in experimental autoimmune myocarditis

Background

An experimental autoimmune myocarditis rat model was established by subcutaneous injection of porcine myocardial myosin (PCM). The effect of ET-1 receptor type B (ETBR) overexpression on autoimmune myocarditis was observed via tail vein injection of ETBR overexpression lentivirus in rats. We further investigated the mechanisms involved in the regulation of autoimmune myocarditis by ETBR overexpression.

Methods

Six rats were randomly selected from 24 male Lewis rats as the NC group, and the remaining 18 rats were injected with PCM on Day 0 and Day 7, to establish the experimental autoimmune myocarditis (EAM) rat model. The 18 rats initially immunized were randomly divided into three groups: the EAM group, ETBR-oe group, and GFP group. On Day 21 after the initial immunization of rats, cardiac echocardiography and serum brain natriuretic peptide (BNP) analysis were performed to evaluate cardiac function, myocardial tissue HE staining was performed to assess myocardial tissue inflammatory infiltration and the myocarditis score, and mRNA expression of IFN-γ, IL-12, and IL-17 was detected by qRT-PCR. Subsequently, immunohistochemical analysis was performed to detect the localization and expression of the ETBR and ICAM-1 proteins, and the expression of ETBR and ICAM-1 was verified by qRT-PCR and western blotting methods.

Results

On Day 21 after initial immunization, left ventricular end-diastolic diameter (LVEDd), left ventricular end-systolic diameter (LVEDs), and serum BNP concentrations increased in the hearts of rats in the EAM group compared with the NC group (P < 0.01), and ejection fraction (EF) and fractional shortening (FS) decreased compared with those of the normal control (NC) group (P < 0.01). LVEDd, LVEDs, and serum BNP concentrations decreased in the ETBR-oe group compared with the EAM group, while EF and FS increased significantly (P < 0.01). HE staining showed that a large number of inflammatory cell infiltrates, mainly lymphocytes, were observed in the EAM group, and the myocarditis score was significantly higher than that of the NC group (P < 0.01). Compared with that of the EAM group, myocardial tissue inflammatory cell infiltration was significantly reduced in the ETBR-oe group, and the myocarditis scores were significantly lower (P < 0.01). The mRNAs of the inflammatory factors IFN-γ, IL-12 and IL-17 in myocardial tissue of rats in the EAM group exhibited elevated levels compared with those of the NC group (P < 0.01) while the mRNAs of IFN-γ, IL-12 and IL-17 were significantly decreased in the ETBR-oe group compared with the EAM group (P < 0.01). Immunohistochemistry showed that the staining depth of ETBR protein in myocardial tissue was greater in the EAM group than in the NC group, and significantly greater in the ETBR-oe group than in the EAM group, while the staining depth of ICAM-1 was significantly greater in the EAM group than in the NC group, and significantly lower in the ETBR-oe group than in the EAM group. The ICAM-1 expression level was significantly higher in the EAM group than in the NC group (P < 0.01), and was significantly lower in the ETBR-oe groupthan in the EAM group (P < 0.01).

The Balance of CD8-Positive T Cells and PD-L1 Expression in the Myocardium Predicts Prognosis in Lymphocytic Fulminant Myocarditis

INTRODUCTION

The clinical significance and prognostic value of T cell involvement and programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) have not been established in lymphocytic fulminant myocarditis (FM). We investigated the prognostic impact of the number of CD4+, CD8+, FoxP3+, and PD-1+ T cells, as well as PD-L1 expression, in cardiomyocytes in lymphocytic FM.

METHODS

This is a single-center observational cohort study. Myocardial tissue was obtained from 16 consecutive patients at lymphocytic FM onset. The median follow-up was 140 days. Cardiac events were defined as a composite of cardiac death and left ventricular-assist device implantation. CD4, CD8, FoxP3, PD-1, and PD-L1 immunostaining were performed on myocardial specimens.

RESULTS

The median age of the patients was 52 years (seven men and nine women). There was no significant difference in the number of CD4+ cells. The number of CD8+ cells and the CD8+/CD4+ T cell ratio were higher in the cardiac event group (Event+) than in the group without cardiac events (Event-) (p = 0.048 and p = 0.022, respectively). The number of FoxP3+ T cells was higher in the Event+ group (p = 0.049). Although there was no difference in the number of PD-1+ cells, cardiomyocyte PD-L1 expression was higher in the Event+ group (p = 0.112). Event-free survival was worse in the group with a high CD8+ cell count (p = 0.012) and high PD-L1 expression (p = 0.049). When divided into three groups based on the number of CD8+ cells and PD-L1 expression (CD8highPD-L1high [n = 8], CD8lowPD-L1high [n = 1], and CD8lowPD-L1low [n = 7]), the CD8highPD-L1high group demonstrated the worst event-free survival, while the CD8lowPD-L1high group had a favorable prognosis without cardiac events (p = 0.041).

CONCLUSION

High myocardial expression of CD8+ T cells and PD-L1 may predict a poor prognosis in lymphocytic FM.

MicroRNAs in Myocarditis-Review of the Preclinical In Vivo Trials

Myocarditis is an inflammatory heart disease with viruses as the most common cause. Regardless of multiple studies that have recently been conducted, the diagnostic options still need to be improved. Although endomyocardial biopsy is known as a diagnostic gold standard, it is invasive and, thus, only sometimes performed. Novel techniques of cardiac magnetic resonance are not readily available. Therapy in viral infections is based mainly on symptomatic treatment, while steroids and intravenous immunoglobulins are used in autoimmune myocarditis. The effectiveness of neither of these methods has been explicitly proven to date. Therefore, novel diagnostic and therapeutic strategies are highly needed. MiRNAs are small, non-coding molecules that regulate fundamental cell functions, including differentiation, metabolism, and apoptosis. They present altered levels in different diseases, including myocarditis. Numerous studies investigating the role of miRNAs in myocarditis have already been conducted. In this review, we discussed only the original preclinical in vivo research. We eventually included 30 studies relevant to the discussed area. The altered miRNA levels have been observed, including upregulation and downregulation of different miRNAs in the mice models of myocarditis. Furthermore, the administration of mimics or inhibitors of particular miRNAs was shown to significantly influence inflammation, morphology, and function of the heart and overall survival. Finally, some studies presented prospective advantages in vaccine development.

Similarities and differences between myocarditis following COVID-19 mRNA vaccine and multiple inflammatory syndrome with cardiac involvement in children

Despite the multiple benefits of vaccination, cardiac adverse Events Following COVID-19 Immunization (c-AEFI) have been reported. These events as well as the severe cardiac involvement reported in Multisystem inflammatory syndrome in children (MIS-C) appear more frequent in young adult males. Herein, we firstly report on the inflammatory profiles of patients experiencing c-AEFI in comparison with age, pubertal age and gender matched MIS-C with cardiac involvement. Proteins related to systemic inflammation were found higher in MIS-C compared to c-AEFI, whereas a higher level in proteins related to myocardial injury was found in c-AEFI. In addition, higher levels of DHEAS, DHEA, and cortisone were found in c-AEFI which persisted at follow-up. No anti-heart muscle and anti-endothelial cell antibodies have been detected. Overall current comparative data showed a distinct inflammatory and androgens profile in c-AEFI patients which results to be well restricted on heart and to persist months after the acute event.

Rationale and design of the ARAMIS trial: Anakinra versus placebo, a double blind randomized controlled trial for the treatment of acute myocarditis

BACKGROUND

Acute myocarditis is an inflammation of the myocardium that can cause life-threatening events. However, anti-inflammatory strategies did not reduce the risk of clinical outcomes in randomized trials. Recently, experimental studies have suggested that specific blockade of the interleukin-1β immune innate pathway could be effective in acute myocarditis.

AIM

To test the hypothesis that inhibition of the interleukin-1β immune innate pathway can reduce the risk of clinical events in acute myocarditis.

METHODS

The "Anakinra versus placebo double blind Randomized controlled trial for the treatment of Acute MyocarditIS" (ARAMIS) trial (ClinicalTrials.gov identifier: NCT03018834) is a national multicentre randomized parallel-group double blind study among symptomatic patients with elevated cardiac troponin and cardiac magnetic resonance-proven acute myocarditis. Patients (n=120) are randomized within 72hours of hospital admission to receive a daily subcutaneous dose of anakinra 100mg or placebo during the hospitalization, in addition to standard of care, including an angiotensin-converting enzyme inhibitor and a beta-blocker. The primary endpoint is the number of days alive free from any myocarditis complication, including ventricular arrhythmias, heart failure, recurrent chest pain requiring medication and ventricular dysfunction (defined as left ventricular ejection fraction<50%), from randomization to 28 days after hospital discharge. At 28 days after discharge, patients with normal left ventricular ejection fraction are then randomized to angiotensin-converting enzyme inhibitor continuation or discontinuation and all patients are followed for 1 year, with regular left ventricular function evaluation.

CONCLUSIONS

ARAMIS is the first trial evaluating inhibition of the interleukin-1β immune innate pathway in the setting of acute myocarditis. Although of small size, it will be the largest randomized trial in acute myocarditis, a serious and poorly studied cardiac condition.

Development and Validation of a Prediction Model on Adult Emergency Department Patients for Early Identification of Fulminant Myocarditis

OBJECTIVE

It is difficult to predict fulminant myocarditis at an early stage in the emergency department. The objective of this study was to construct and validate a simple prediction model for the early identification of fulminant myocarditis.

METHODS

A total of 61 patients with fulminant myocarditis and 160 patients with acute myocarditis were enrolled in the training and internal validation cohorts. LASSO regression and multivariate logistic regression were selected to develop the prediction model. The selection of the model was based on overall performance and simplicity. A nomogram based on the optimal model was built, and its clinical usefulness was evaluated by decision curve analysis. The predictive model was further validated in an external validation group.

RESULTS

The resulting prediction model was based on 4 factors: systolic blood pressure, troponin I, left ventricular ejection fraction, and ventricular wall motion abnormality. The Brier scores of the final model were 0.078 in the training data set and 0.061 in the internal testing data set, respectively. The C-indexes of the training data set and the testing data set were 0.952 and 0.968, respectively. Decision curve analysis showed that the nomogram model developed based on the 4 predictors above had a positive net benefit for predicting probability thresholds. In the external validation cohort, the model also showed good performance (Brier score=0.007, and C-index=0.989).

CONCLUSION

We developed and validated an early prediction model consisting of 4 clinical factors (systolic blood pressure, troponin I, left ventricular ejection fraction, and ventricular wall motion abnormality) to identify potential fulminant myocarditis patients in the emergency department.

Association between recently raised anticholinergic burden and risk of acute cardiovascular events: nationwide case-case-time-control study

OBJECTIVE

To evaluate the association between recently raised anticholinergic burden and risk of acute cardiovascular events in older adults.

DESIGN

Case-case-time-control study (ie, incorporating a case crossover design and a control crossover design consisting of future cases).

SETTING

Taiwan's National Health Insurance Research Database.

PARTICIPANTS

317 446 adults aged ≥65 who were admitted to hospital because of an incident acute cardiovascular event between 2011 and 2018. Acute cardiovascular events included myocardial infarction, strokes, arrhythmias, conduction disorders, and cardiovascular death.

MAIN OUTCOME MEASURES

The anticholinergic burden was measured for each participant by adding up the anticholinergic scores for individual drugs using the Anticholinergic Cognitive Burden Scale. Scores were classified into three levels (0 points, 1-2 points, and ≥3 points). For each participant, anticholinergic burden levels during hazard periods (day -1 to -30 before the cardiovascular event) were compared with randomly selected 30 day reference periods (ie, periods between days -61 and -180). Conditional logistic regression determined odds ratios with 95% confidence intervals to evaluate the association between acute cardiovascular events and recently raised anticholinergic burden.

RESULTS

The crossover analyses included 248 579 current cases. Participants' average age on the index date was 78.4 years (standard deviation 0.01), and 53.4% were men. The most frequently prescribed drugs with anticholinergic activity were antihistamines (68.9%), gastrointestinal antispasmodics (40.9%), and diuretics (33.8%). Among patients with varying levels of anticholinergic burden in different periods, more patients carried higher levels of anticholinergic burden during hazard periods than during reference periods. For example, 17 603 current cases had 1-2 points of anticholinergic burden in the hazard period with 0 points in the reference period, while 8507 current cases had 0 points in the hazard period and 1-2 points in the reference period. In the comparison of 1-2 points versus 0 points of anticholinergic burden, the odds ratio was 1.86 (95% confidence interval 1.83 to 1.90) in the case crossover analysis and 1.35 (1.33 to 1.38) in the control crossover analysis, which yielded a case-case-time-control odds ratio of 1.38 (1.34 to 1.42). Similar results were found in the comparison of ≥3 versus 0 points (2.03, 1.98 to 2.09) and ≥3 versus 1-2 points (1.48, 1.44 to 1.52). The findings remained consistent throughout a series of sensitivity analyses (eg, cut-off points for anticholinergic burden categories were redefined and different scales were used to measure anticholinergic burden).

CONCLUSIONS

An association was found between recently raised anticholinergic burden and increased risk of acute cardiovascular events. Furthermore, a greater increase in anticholinergic burden was associated with a higher risk of acute cardiovascular events.

Myocarditis post-COVID-19 vaccination

There has been much interest in the possible adverse events associated with available anti-coronavirus disease of 2019 (COVID-19) vaccines, given the rapid pace at which they had to be developed during the pandemic. One such adverse event is myocarditis post-COVID-19 vaccination. Several pathophysiological mechanisms have been proposed that might help us understand the relationship between the messenger ribonucleic acid (mRNA) vaccine and the occurrence of myocarditis, though we are yet to ascertain the causal link between them. Although the actual absolute incidence of myocarditis post-COVID-19 vaccination remains low among the large, general population that has been vaccinated, there has been a high relative incidence of this adverse event. We aim to review the existing literature and bring to light what we have so far understood with respect to the association between COVID-19 vaccination and myocarditis. This will help in better understanding the burden of the pathology along with alleviating apprehensions associated with it.

KEY MESSAGES

Immunopathogenesis and immunomodulatory therapy for myocarditis

Myocarditis is an inflammatory cardiac disease characterized by the destruction of myocardial cells, infiltration of interstitial inflammatory cells, and fibrosis, and is becoming a major public health concern. The aetiology of myocarditis continues to broaden as new pathogens and drugs emerge. The relationship between immune checkpoint inhibitors, severe acute respiratory syndrome coronavirus 2, vaccines against coronavirus disease-2019, and myocarditis has attracted increased attention. Immunopathological processes play an important role in the different phases of myocarditis, affecting disease occurrence, development, and prognosis. Excessive immune activation can induce severe myocardial injury and lead to fulminant myocarditis, whereas chronic inflammation can lead to cardiac remodelling and inflammatory dilated cardiomyopathy. The use of immunosuppressive treatments, particularly cytotoxic agents, for myocarditis, remains controversial. While reasonable and effective immunomodulatory therapy is the general trend. This review focuses on the current understanding of the aetiology and immunopathogenesis of myocarditis and offers new perspectives on immunomodulatory therapies.

Epidemiology, characteristics, treatments, and outcomes of adult-onset Still's disease in Afro-Caribbeans: Results from a population-based study in Martinique, French West Indies

OBJECTIVES

To describe the epidemiology, characteristics, response to initial treatment, and outcomes of Adult-Onset Still's disease (AOSD) in the Afro-Caribbean population of Martinique with free and easy access to specialised care.

METHODS

We conducted a retrospective study from 2004 to 2022 in the island of Martinique, French West-Indies which total population was 354 800 in 2021. Patients were identified from multiple sources including standardised databases. To be included, patients had to be residents of the island and fulfilled Yamaguchi and/or Fautrel's criteria for AOSD, or have a compatible disease course, without a diagnosis of cancer, auto-immune disease or another auto-inflammatory disorder. Date of diagnosis, clinical and biological characteristics, treatments, and outcomes were collected.

RESULTS

The prevalence was 7.6/100 000 inhabitants in 2021. The mean incidence was 0.4/100 000 during study period. Thirty-three patients (70.6% females) with a median follow-up of 35 months [7.5 to 119] were included. Twenty-six patients (78.8%) had a systemic pattern. Patients with a systemic monocyclic pattern had significantly more polyarticular involvement than patients with systemic polycyclic pattern (p = 0.016). Pulmonary involvement occurred in 51.5% of patients at diagnosis and systemic Pouchot score has been identified as an independent predictive factor for pulmonary involvement; OR of 3.29 [CI 95% 1.20; 9.01]. At first flare, all patients but one received oral glucocorticoids, 11 patients (32.4%) received intravenous glucocorticoids pulse and 12 patients (33%) received anti-IL1 therapy. Nineteen patients (57%) relapsed in a median time of 9 months [6 to 12] Three patients (9%) developed hemophagocytosis lymphohistiocytosis, fatal in 1 case. All deceased patients (n = 4, 11.76%) belonged to the systemic polycyclic pattern, with an event-free survival of 13.6 months [IQR 5.7; 29.5] CONCLUSION: AOSD in the Afro-Caribbean population of Martinique shares some similarities with other ethnic groups, but exhibit differences, such as a high proportion of lung involvement. Comparative studies are needed to confirm these results.