The spectrum of myocarditis: from pathology to the clinics

Endosomal Toll-Like Receptors intermediate negative impacts of viral diseases, autoimmune diseases, and inflammatory immune responses on the cardiovascular system

INTRODUCTION

Cardiovascular disease (CVD) is the leading cause of morbidity globally, with chronic inflammation as a key modifiable risk factor. Toll-like receptors (TLRs), pivotal components of the innate immune system, including TLR-3, -7, -8, and -9 within endosomes, trigger intracellular cascades, leading to inflammatory cytokine production by various cell types, contributing to systemic inflammation and atherosclerosis. Recent research highlights the role of endosomal TLRs in recognizing self-derived nucleic acids during sterile inflammation, implicated in autoimmune conditions like myocarditis.

AREAS COVERED

This review explores the impact of endosomal TLRs on viral infections, autoimmunity, and inflammatory responses, shedding light on their intricate involvement in cardiovascular health and disease by examining literature on TLR-mediated mechanisms and their roles in CVD pathophysiology.

EXPERT OPINION

Removal of endosomal TLRs mitigates myocardial damage and immune reactions, applicable in myocardial injury. Targeting TLRs with agonists enhances innate immunity against fatal viruses, lowering viral loads and mortality. Prophylactic TLR agonist administration upregulates TLRs, protecting against fatal viruses and improving survival. TLRs play a complex role in CVDs like atherosclerosis and myocarditis, with therapeutic potential in modulating TLR reactions for cardiovascular health.

Efficacy and safety of creatine phosphate sodium in the treatment of viral myocarditis: A systematic review and meta-analysis

PURPOSE

To systematically evaluate the efficacy and safety of creatine phosphate sodium in the treatment of viral myocarditis, and to provide guidance for its clinical treatment.

METHODS

We conducted a search of The Cochrane Library, PubMed, EMbase, and Web of Science databases to retrieve randomized controlled trials (RCTs) on the use of creatine phosphate sodium (CPS) in the treatment of viral myocarditis. The search was conducted up to April 2024. After screening the literature, extracting data, and evaluating the risk of bias in the included studies, we performed a meta-analysis using RevMan 5.4 and Stata17.0 statistical software.

RESULTS

A total of 104 articles were retrieved, and 9 articles with a combined total of 1,116 patients were ultimately included in the meta-analysis. The results of the meta-analysis indicated that the overall efficacy rate in the phosphocreatine sodium treatment group was higher than that in the control group [RR = 1.22, 95%CI (1.15, 1.28), P<0.00001]. Furthermore, post-treatment levels of cardiac troponin I [MD = 0.1, 95%CI (0.07, 0.13), P<0.00001] and creatine kinase isoenzyme [MD = 9.43, 95%CI (7.04,11 .82), P<0 .00001] in the phosphocreatine treatment group were lower compared to those in the control group; both differences between groups were statistically significant. Additionally, there was no significant difference observed in adverse reaction incidence between the phosphocreatine sodium treatment group and conventional treatment group [RR = 1 .07, 95% CI (0 .68, 1 .67), P = O .77].

CONCLUSION

Creatine phosphate sodium treatment can significantly improve the therapeutic effect of patients with viral myocarditis, and can reduce the levels of cTnI and CK-MB. Compared with conventional treatment, it has good safety.

Creatine phosphate improves myocardial function and myocardial enzyme profile in children with myocarditis

Myocarditis in children is more common in clinical practice, which can cause different degrees of cardiac function damage. We investigated the effects of creatine phosphate in the treatment of myocarditis in children. Children in the control group were treated with sodium fructose diphosphate, and children in the observation group were treated with creatine phosphate on the basis of the control group. After treatment, the myocardial enzyme profile and cardiac function of children in the observation group were better than the control group. The total effective rate of treatment for children in the observation group was higher than that in the control group. In conclusion, creatine phosphate could significantly improve myocardial function, improve myocardial enzyme profile and reduce myocardial damage in children with pediatric myocarditis and had a high safety of use, which was worthy of clinical promotion.

Atlas of Regional Left Ventricular Scar in Nonischemic Cardiomyopathies: Substrates and Etiologies

Most acquired and inherited cardiomyopathies are characterized by regional left ventricular involvement and nonischemic myocardial scars, often with a disease-specific pattern. Irrespective of the etiology and pathophysiological mechanisms, myocardial disorders are invariably associated with cardiac fibrosis, which contributes to dysfunction and electrical instability. Accordingly, cardiac magnetic resonance plays a central role in the diagnostic work-up and prognostic risk stratification of cardiomyopathies, particularly with the increasing correlation between genetic background and specific disease phenotype. Starting from pattern and distribution of myocardial fibrosis at cardiac magnetic resonance, we provide a practical regional atlas of nonischemic myocardial scar to guide the diagnostic approach to nonischemic cardiomyopathies.

Diagnostic Value of Cardiovascular Magnetic Resonance T1 and T2 Mapping in Acute Myocarditis: A Systematic Literature Review

Background and Objectives: Over the past decade, there has been increasing attention paid to advanced and innovative cardiovascular magnetic resonance (CMR) modalities, such as T1 and T2 mapping, which play a major role in diagnosing diffuse myocardial disease. There is little data summarizing the current evidence regarding the diagnostic accuracy of T1 and T2 mapping, and extracellular volume (ECV) in acute myocarditis. The aim of our study was to select, analyze, and systematically review the recent scientific literature on the diagnostic value of CMR T1 and T2 parametric mapping in clinically suspected acute myocarditis. Materials and Methods: The literature search was performed in the PubMed database. Articles published in the years 2014-2024 were included in the analysis. At the initial stage, 458 articles were reviewed, and 13 exploratory research studies were further analyzed and presented in this systematic literature review. Results: The analysis included 686 patients with clinically suspected myocarditis and 372 subjects in the control group. The average age of patients with suspected myocarditis was 40.25 years; 26% of them were women. Prolonged native myocardial T1 relaxation time provides diagnostic accuracy in the setting of suspected acute myocarditis ranging from 69 to 99%, with sensitivity from 64 to 98% and specificity from 87 to 100%. Diagnostic accuracy of prolonged T2 relaxation time ranges from 47 to 87%, with sensitivity being from 48% to 94% and specificity from 60% to 92%. ECV alone showed moderate diagnostic performance, with diagnostic accuracy ranging from 62% to 76%, sensitivity from 47% to 73%, and specificity from 76% to 90%. T1 and T2 mapping and ECV, combined with the late gadolinium enhancement (LGE) technique, increases the probability of detecting myocardial inflammatory changes at various stages of the disease, improving the diagnostic accuracy to 96%. Conclusions: New quantitative CMR techniques, i.e., T1 and T2 mapping, have an advantage over conventional CMR sequences in detecting inflammatory myocardial structural changes and play an important role in diagnosing acute myocarditis. Incorporating these sequences in daily clinical practice increases the diagnostic value of CMR in acute myocarditis and becomes an alternative to endomyocardial biopsy, which has been considered the gold standard until now.

Neutrophilic Myocarditis: Insights from a Forensic Centre's Retrospective Study

BACKGROUND

Neutrophilic myocarditis often stems from bacterial or fungal infections, and it is typically detectable through blood cultures or analyses of the primary infection site. However, research specifically addressing the morphological features of acute myocarditis in complex sepsis cases is scarce, with existing studies primarily dating back to the pre-antibiotic era.

METHODS

This study constitutes a retrospective and descriptive analysis encompassing 22 forensic cases. We collected data from forensic reports emphasising clinical details, disease history, gross observations, and histopathological findings.

RESULTS

The results show that using positive-air-pressure ventilation could be related to cardiac inflammation (45.45%, 10/22). Despite large-spectrum antibiotic therapy, the blood samples were positive for Staphylococcus aureus (MRSA strain), Klebsiella pneumoniae (ESBL strain), Acinetobacter baumannii, and Pseudomonas aeruginosa. Colonies developed in the myocardium of 36% of the patients (8/22), where 4 of them had septic emboli. Fungal myocarditis accompanied bacterial infections (2/8) and were unsuspected clinically. Background changes, such as interstitial fibrosis and arteriosclerosis, were associated with a greater degree of inflammation and septic embolism.

CONCLUSION

Neutrophilic myocarditis in patients with emerging sepsis is linked to fatal virulent infections, where bacteria and/or fungi contaminate and impair the myocardium syncytium. Prolonged hospitalisation and positive-air-pressure ventilation may be a risk factor for this condition and needs further 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.

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.

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.

The inflammatory spectrum of cardiomyopathies

Infiltration of the myocardium with various cell types, cytokines and chemokines plays a crucial role in the pathogenesis of cardiomyopathies including inflammatory cardiomyopathies and myocarditis. A more comprehensive understanding of the precise immune mechanisms involved in acute and chronic myocarditis is essential to develop novel therapeutic approaches. This review offers a comprehensive overview of the current knowledge of the immune landscape in cardiomyopathies based on etiology. It identifies gaps in our knowledge about cardiac inflammation and emphasizes the need for new translational approaches to improve our understanding thus enabling development of novel early detection methods and more effective treatments.

Optimal timing of follow-up cardiac magnetic resonance in patients with uncomplicated acute myocarditis

BACKGROUND

Cardiac magnetic resonance (CMR) is central in the diagnosis and prognostic stratification of acute myocarditis (AM) but the timing of repeated CMR scans to assess edema resolution and late gadolinium enhancement (LGE) stabilization remain unclear. We assessed edema and LGE evolution over 12 months to identify the optimal timing of repeat CMR evaluation in AM.

METHODS AND RESULTS

Thirty-three consecutive patients with AM underwent CMR at clinical presentation (CMR-1), after 3 months (CMR-2) and after 12-months (CMR-3). CMR included assessment of edema and LGE, left ventricular ejection fraction (LVEF) and left ventricular mass index (LVMi). After CMR-3 patients were followed-up every three-months by clinical evaluation, Holter-monitoring, and echocardiography. All patients had edema and LGE at CMR-1. At CMR-2 edema-positive segments (0.42 ± 0.34 vs. 3.18 ± 2.33, p < 0.005), LGE (4.98 ± 4.56 vs. 9.60 ± 8.58 g, and 4.22 ± 3.97% vs 7.50 ± 5.61%) and LVMi (69.82 ± 11.83 vs 76.06 ± 13.13 g/m2) (all p < 0.0001) significantly reduced, while LVEF (63.12 ± 5.47% vs.61.15 ± 6.87% p < 0.05) significantly improved, compared to CMR-1. At CMR-2 edema persisted in 7 patients (21%) but resolved at CMR-3 with no further changes of LVMi, LVEF and LGE. During follow-up (85 ± 15 months), 5 (15%) patients showed persistent ventricular arrhythmias. Univariate predictors of arrhythmic persistence were LGE extension at CMR-2 and CMR-3 (both p < 0.05), but not at CMR-1 (p = 0.07).

CONCLUSIONS

Most patients with uncomplicated AM show edema resolution with LGE stabilization after 3 months. Further CMR evaluations should be limited to patients with persisting edema at this time. LGE extent measured after edema resolution is associated with persistent ventricular arrhythmias.

Fatal Myocarditis following COVID-19 mRNA Immunization: A Case Report and Differential Diagnosis Review

Carditis in childhood is a rare disease with several etiologies. We report a case of infant death due to pericarditis and myocarditis after the mRNA vaccine against COVID-19 (COVIDmRNAV). A 7-year-old male child received the first dose of the COVIDmRNAV and presented with monoarthritis and a fever non-responsive to oral antibiotics. The laboratory investigation showed signs of infection (leukocytosis, high levels of c-reactive protein). His condition rapidly deteriorated, and the patient died. The autopsy identified pericardial fibrin deposits, hemorrhagic areas in the myocardium, and normal valves. A diffuse intermyocardial inflammatory infiltrate composed of T CD8+ lymphocytes and histiocytes was identified. An antistreptolysin O (ASO) dosage showed high titers. The presence of arthritis, elevated ASO, and carditis fulfills the criteria for rheumatic fever. However, valve disease and Aschoff's nodules, present in 90% of rheumatic carditis cases, were absent in this case. The temporal correlation with mRNA vaccination prompted its inclusion as one of the etiologies. In cases of myocardial damage related to COVID-19mRNAV, it appears to be related to the expression of exosomes and lipid nanoparticles, leading to a cytokine storm. The potential effects of the COVID-19mRNAV must be considered in the pathogenesis of this disease, whether as an etiology or a contributing factor to a previously initiated myocardial injury.

Investigation into Cardiac Myhc-α 334-352-Specific TCR Transgenic Mice Reveals a Role for Cytotoxic CD4 T Cells in the Development of Cardiac Autoimmunity

Myocarditis is one of the major causes of heart failure in children and young adults and can lead to dilated cardiomyopathy. Lymphocytic myocarditis could result from autoreactive CD4+ and CD8+ T cells, but defining antigen specificity in disease pathogenesis is challenging. To address this issue, we generated T cell receptor (TCR) transgenic (Tg) C57BL/6J mice specific to cardiac myosin heavy chain (Myhc)-α 334-352 and found that Myhc-α-specific TCRs were expressed in both CD4+ and CD8+ T cells. To investigate if the phenotype is more pronounced in a myocarditis-susceptible genetic background, we backcrossed with A/J mice. At the fourth generation of backcrossing, we observed that Tg T cells from naïve mice responded to Myhc-α 334-352, as evaluated by proliferation assay and carboxyfluorescein succinimidyl ester staining. The T cell responses included significant production of mainly pro-inflammatory cytokines, namely interferon (IFN)-γ, interleukin-17, and granulocyte macrophage-colony stimulating factor. While the naïve Tg mice had isolated myocardial lesions, immunization with Myhc-α 334-352 led to mild myocarditis, suggesting that further backcrossing to increase the percentage of A/J genome close to 99.99% might show a more severe disease phenotype. Further investigations led us to note that CD4+ T cells displayed the phenotype of cytotoxic T cells (CTLs) akin to those of conventional CD8+ CTLs, as determined by the expression of CD107a, IFN-γ, granzyme B natural killer cell receptor (NKG)2A, NKG2D, cytotoxic and regulatory T cell molecules, and eomesodermin. Taken together, the transgenic system described in this report may be a helpful tool to distinguish the roles of cytotoxic cardiac antigen-specific CD4+ T cells vs. those of CD8+ T cells in the pathogenesis of myocarditis.

Post-COVID-19 Vaccination Myocarditis: A Histopathologic Study on a Monocentric Series of Six Cases

Many reports on the development of myocarditis following coronavirus disease 2019 (COVID-19) vaccination (PCVM) have emerged. However, only a few case studies have investigated endomyocardial biopsy (EMB) results. This study describes the clinicopathologic features of PCVM. We surveyed all hospitalized patients in a single university hospital in Korea and identified six cases of PCVM. All six patients underwent EMB, five of whom were men aged 15-85 years. All patients developed cardiac dysfunction. Among these patients, two had mild disease without sequelae, whereas the other four had dilated cardiomyopathy with depressed cardiac function. All six cases demonstrated lymphohistiocytic myocarditis. Two of our cases fulfilled the criterion of CD3+ T lymphocytes > 7 cells/mm2 (Case nos. 3 and 6), while the remaining four cases did not fulfill the Dallas criteria. In conclusion, most PCVM cases showed mild degree inflammation histopathologically, and some cases could not fulfill the Dallas criteria and were classified as borderline myocarditis.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

Multifunctional nanoparticle-mediated combining therapy for human diseases

Combining existing drug therapy is essential in developing new therapeutic agents in disease prevention and treatment. In preclinical investigations, combined effect of certain known drugs has been well established in treating extensive human diseases. Attributed to synergistic effects by targeting various disease pathways and advantages, such as reduced administration dose, decreased toxicity, and alleviated drug resistance, combinatorial treatment is now being pursued by delivering therapeutic agents to combat major clinical illnesses, such as cancer, atherosclerosis, pulmonary hypertension, myocarditis, rheumatoid arthritis, inflammatory bowel disease, metabolic disorders and neurodegenerative diseases. Combinatorial therapy involves combining or co-delivering two or more drugs for treating a specific disease. Nanoparticle (NP)-mediated drug delivery systems, i.e., liposomal NPs, polymeric NPs and nanocrystals, are of great interest in combinatorial therapy for a wide range of disorders due to targeted drug delivery, extended drug release, and higher drug stability to avoid rapid clearance at infected areas. This review summarizes various targets of diseases, preclinical or clinically approved drug combinations and the development of multifunctional NPs for combining therapy and emphasizes combinatorial therapeutic strategies based on drug delivery for treating severe clinical diseases. Ultimately, we discuss the challenging of developing NP-codelivery and translation and provide potential approaches to address the limitations. This review offers a comprehensive overview for recent cutting-edge and challenging in developing NP-mediated combination therapy for human diseases.

Acute myocarditis secondary to Campylobacter jejuni enteritis: A case report

Acute myocarditis is a rare complication of Campylobacter jejuni enteritis. Herein, we report the case of a 20-year-old man who presented with chest pain that developed three days after the onset of enteritis. Electrocardiogram, echocardiogram, and cardiac enzyme levels suggested myocarditis. Cardiac magnetic resonance imaging revealed a late gadolinium enhancement in the inferior wall. Degeneration and necrosis of myocardial cells and lymphocyte-dominant inflammatory cell infiltration were found in the tissue obtained by endomyocardial biopsy. Acute myocarditis associated with C. jejuni enteritis was confirmed by these findings and C. jejuni detected in the stool culture. The symptoms of enteritis and myocarditis remitted 10 days after the onset. The left ventricular ejection fraction was improved from 40 % to 57 %.In previous cases, endomyocardial biopsy has not been performed because of mild myocarditis. The lack of pathological reports makes the mechanism of myocarditis associated with C. jejuni enteritis unknown. We report a case of myocarditis associated with C. jejuni enteritis, which was diagnosed using cardiac magnetic resonance imaging and endomyocardial biopsy.

Learning objective

Acute myocarditis is a rare but important complication of Campylobacter jejuni enteritis. Cardiac magnetic resonance imaging is useful for diagnosis. Most cases of myocarditis associated with C. jejuni enteritis were mild and remitted without specific treatment. In the present case, endomyocardial biopsy was performed and CD4-positive lymphocytes were predominantly detected in the myocardial tissue.

Transgenic Mice Expressing Functional TCRs Specific to Cardiac Myhc-α 334-352 on Both CD4 and CD8 T Cells Are Resistant to the Development of Myocarditis on C57BL/6 Genetic Background

Myocarditis is a predominant cause of congestive heart failure and sudden death in children and young adolescents that can lead to dilated cardiomyopathy. Lymphocytic myocarditis mediated by T cells can result from the recognition of cardiac antigens that may involve CD4 or CD8 T cells or both. In this report, we describe the generation of T cell receptor (TCR) transgenic mice on a C57BL/6 genetic background specific to cardiac myosin heavy chain (Myhc)-α 334-352 and make the following observations: First, we verified that Myhc-α 334-352 was immunogenic in wild-type C57BL/6 mice and induced antigen-specific CD4 T cell responses despite being a poor binder of IAb; however, the immunized animals developed only mild myocarditis. Second, TCRs specific to Myhc-α 334-352 in transgenic mice were expressed in both CD4 and CD8 T cells, suggesting that the expression of epitope-specific TCR is common to both cell types. Third, although T cells from naïve transgenic mice did not respond to Myhc-α 334-352, both CD4 and CD8 T cells from animals immunized with Myhc-α 334-352 responded to the peptide, indicating that antigen priming is necessary to break tolerance. Fourth, although the transgenic T cells could produce significant amounts of interferon-γ and interleukin-17, the immunized animals developed only mild disease, indicating that other soluble factors might be necessary for developing severe myocarditis. Alternatively, the C57BL/6 genetic background might be a major contributing factor for resistance to the development of myocarditis. Taken together, our model permits the determination of the roles of both CD4 and CD8 T cells to understand the disease-resistance mechanisms of myocarditis in a single transgenic system antigen-specifically.

Aggravation of TGFβ1-Smad Pathway and Autoimmune Myocarditis by Fungicide (Tebuconazole) Exposure

Myocarditis is an inflammatory cardiac disorder and the primary cause of heart failure in young adults. Its origins can be attributed to various factors, including bacterial or viral infections, exposure to toxins or drugs, endocrine disruptors (EDs), and autoimmune processes. Tebuconazole (TEB), which is a member of the triazole fungicide family, is utilized to safeguard agricultural crop plants against fungal pathogens. Although TEB poses serious threats to mammal health, the information about how it induces toxic effects through various pathways, particularly in autoimmune diseases, are still limited. Thus, the aim of this paper was to evaluate the effect of TEB exposure in autoimmune myocarditis (AM). To induce AM, rats were immunized with porcine cardiac myosin and exposed to TEB for 21 days. Thereafter, animals were sacrificed, and histological, biochemical, and molecular analyses were performed. TEB exposure increased heart weight, systolic blood pressure and heart rate already augmented by AM. Additionally, it significantly increased creatine phosphokinase heart (CK-MB), creatine phosphokinase (CPK), cardiac troponin T (cTnT), and cardiac troponin I (cTnI), as compared to the control. From the histological perspective, TEB exacerbates the histological damage induced by AM (necrosis, inflammation and cell infiltration) and increased fibrosis and collagen deposition. TEB exposure strongly increased pro-inflammatory cytokines and prooxidant levels (O2^-, H₂O₂, NO₂^-, lipid peroxidation) and reduced antioxidant enzyme levels, which were already dysregulated by AM. Additionally, TEB increased NOX-4 expression and the TGFβ1-Smads pathway already activated by AM. Overall, our results showed that TEB exposure strongly aggravated the cardiotoxicity induced by AM.

Could Zonulin and Presepsin Be Biomarkers and Therapeutic Targets for Acute Myocarditis?

BACKGROUND

The diagnosis of acute myocarditis is usually made with clinical and laboratory parameters. This can sometimes be mixed up with diseases that have similar clinical features, making the diagnosis difficult. Therefore, the use of more specific biomarkers, in addition to the classically used biomarkers such as troponin, will accelerate the diagnosis. In addition, these biomarkers may help us to understand the mechanism of myocarditis development and thus predict unpredictable clinical outcomes.

OBJECTIVE

This study aims to reveal the possible relationship between intestinal permeability and acute myocarditis.

METHODS

In this study, we wanted to evaluate serum levels of zonulin and presepsin in 138 consecutive subjects, including 68 patients with myocarditis and another 70 as the control group, matched for age, gender, and cardiovascular risk factors. P-values <0.05 were considered to be statistically significant.

RESULTS

Compared to the control group, zonulin and presepsin were significantly higher in the patient group with myocarditis (p < 0.001, for all). Zonulin levels were positively correlated with presepsin, peak CK-MB, and peak troponin levels (r = 0.461, p < 0.001; r = 0.744, p < 0.001; r = 0.627, p < 0.001; respectively). In regression analysis, presepsin and zonulin were determined as independent predictors for myocarditis (OR 1.002, 95% CI 1.001-1.003, p = 0.025; OR 12.331, 95% CI 4.261-35.689; p < 0.001; respectively). The predictive value of acute myocarditis of presepsin and zonulin in ROC curve analysis was statistically significant (p < 0.001, for both).

CONCLUSION

This study showed that zonulin and presepsin could be biomarkers that can be used in the diagnosis of myocarditis, and they can also be therapeutic targets by shedding light on the developmental mechanism of myocarditis.

Immunomodulatory Therapy for Giant Cell Myocarditis: A Narrative Review

Giant cell myocarditis (GCM) is a rare, often rapidly progressive, and potentially fatal disease because of myocardium inflammation due to the infiltration of giant cells triggered by infectious as well as non-infectious etiologies. Several studies have reported that GCM can occur in patients of all ages but is more commonly found in adults. It is relatively more common among African American and Hispanic patients than in the White population. Early diagnosis and treatment are critical. Electrocardiogram (EKG), complete blood count, erythrocyte sedimentation rate, C-reactive protein, and cardiac biomarkers such as troponin and brain natriuretic peptide (BNP), echocardiogram, cardiac magnetic resonance imaging (MRI), myocardial biopsy, and myocardial gene profiling are useful diagnostic tools. Current research has identified several potential biomarkers for GCM, including myocarditis-associated immune cells, cytokines, and other chemicals. The standard of care for GCM includes aggressive immunosuppressive therapy with corticosteroids and immunomodulatory agents like rituximab, cyclosporine, and infliximab, which have shown promising results in GCM by balancing the immune system and preventing the attack on healthy tissues, resulting in the reduction of inflammation, promotion of healing, and decreasing the necessity for cardiac transplantation. Without immunosuppression, the chance of mortality or cardiac surgery was 100%. Multiple studies have revealed that a treatment combination of corticosteroids and immunomodulatory agents is superior to corticosteroids alone. Combination therapy significantly increased transplant-free survival (TFS) and decreased the likelihood of heart transplantation, hence improving overall survival. It is important to balance the benefits of immunosuppression with its potentially adverse effects. In conclusion, immunomodulatory therapy adds significant long-term survival benefits to GCM.

Revitalizing myocarditis treatment through gut microbiota modulation: unveiling a promising therapeutic avenue

Numerous studies have demonstrated that gut microbiota plays an important role in the development and treatment of different cardiovascular diseases, including hypertension, heart failure, myocardial infarction, arrhythmia, and atherosclerosis. Furthermore, evidence from recent studies has shown that gut microbiota contributes to the development of myocarditis. Myocarditis is an inflammatory disease that often results in myocardial damage. Myocarditis is a common cause of sudden cardiac death in young adults. The incidence of myocarditis and its associated dilated cardiomyopathy has been increasing yearly. Myocarditis has gained significant attention on social media due to its association with both COVID-19 and COVID-19 vaccinations. However, the current therapeutic options for myocarditis are limited. In addition, little is known about the potential therapeutic targets of myocarditis. In this study, we review (1) the evidence on the gut-heart axis, (2) the crosslink between gut microbiota and the immune system, (3) the association between myocarditis and the immune system, (4) the impact of gut microbiota and its metabolites on myocarditis, (5) current strategies for modulating gut microbiota, (6) challenges and future directions for targeted gut microbiota in the treatment of myocarditis. The approach of targeting the gut microbiota in myocarditis is still in its infancy, and this is the study to explore the gut microbiota-immune system-myocarditis axis. Our findings are expected to pave the way for the use of gut microbiota as a potential therapeutic target in the treatment of myocarditis.

Commentary on why implementing and standardizing histologic diagnosis of myocarditis is crucial for the clinical setting and patient care

Histological examination of endomyocardial biopsy or myocardium at autopsy is key to the diagnosis of myocarditis. Among pathologists there is currently extensive variability in routine practice and criteria used to define, diagnose, and report myocarditis as well as to achieve consensus on cases. Two manuscripts emphasizing the need to standardize and implement histopathological diagnostic criteria for myocarditis are reviewed.

COVID-19-Induced Myocarditis: Pathophysiological Roles of ACE2 and Toll-like Receptors

The clinical manifestations of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection responsible for coronavirus disease 2019 (COVID-19) commonly include dyspnoea and fatigue, and they primarily involve the lungs. However, extra-pulmonary organ dysfunctions, particularly affecting the cardiovascular system, have also been observed following COVID-19 infection. In this context, several cardiac complications have been reported, including hypertension, thromboembolism, arrythmia and heart failure, with myocardial injury and myocarditis being the most frequent. These secondary myocardial inflammatory responses appear to be associated with a poorer disease course and increased mortality in patients with severe COVID-19. In addition, numerous episodes of myocarditis have been reported as a complication of COVID-19 mRNA vaccinations, especially in young adult males. Changes in the cell surface expression of angiotensin-converting enzyme 2 (ACE2) and direct injury to cardiomyocytes resulting from exaggerated immune responses to COVID-19 are just some of the mechanisms that may explain the pathogenesis of COVID-19-induced myocarditis. Here, we review the pathophysiological mechanisms underlying myocarditis associated with COVID-19 infection, with a particular focus on the involvement of ACE2 and Toll-like receptors (TLRs).

Ultra Short Heart Rate Variability Predicts Clinical Outcomes in Patients with a Clinical Presentation Consistent with Myocarditis: A Derivation Cohort Analysis

Myocarditis prognosis varies substantially, hence identification of novel prognostic factors is crucial. The prognostic role of ultra-short heart-rate variability (HRV) in myocarditis remains unknown. In a retrospective study, adult patients admitted to a tertiary hospital due to clinically suspected myocarditis were included. Clinical, laboratory and HRV parameters were assessed as predictors of severe short term complications (heart failure (HF), dilated cardiomyopathy—DCM, ventricular arrhythmia—VA and death), utilizing logistic regression (LR). Accuracy was evaluated with receiver operating characteristic (ROC) curve area under the curve (AUC). HRV indices included standard deviation of normal beat intervals (SDNN) and root mean square of successive differences (RMSSD). 115 patients, aged 34 (±13) years old, were examined. Six patients (5%) developed severe HFrEF. RMSSD was included in a multivariate LR model (RMSSD < 10.72 ms adjusted odds ratio (AOR) 14.056, p-value 0.024). Model classification accuracy was very good, with an AUC of 86%. Eight patients (7%) developed DCM. RMSSD < 10.72 ms was included in a multivariate classification model (AOR 8.826, p-value 0.013); model classification AUC of 82%. HRV did not predict development of VA or death. SDNN and especially RMSSD may be prognostic indicators in myocarditis.

Deep Learning-Based Medical Data Association Rules to Explore the Connectivity and Regulation Mechanism of miRNA-mRNA Network in Myocarditis

Acute, chronic myocarditis as myocardial localized or diffuse inflammation lesions is usually involving cardiac function in patients with severe adverse outcomes such as heart failure, sudden death, and no unified, but its pathogenesis clinical is mainly composed of a number of factors including infection and autoimmune defects, such as physical and chemical factors; therefore, it is of great significance to explore the regulation mechanism of myocarditis-related miRNA network connectivity and temperament for in-depth understanding of the pathogenesis of myocarditis and the direction of targeted therapy. Based on this, this study explored the miRNA network related to the pathogenesis of myocarditis through deep learning medical data association rules and analyzed its specific mechanism. The results showed that 39 upregulated miRNAs, 88 downregulated miRNAs, 109 upregulated differentially expressed miRNAs, and 589 downregulated mRNAs were obtained by data association through GSE126677 and GSE4172 databases. GO enrichment and KRGG enrichment analysis showed that the differentially expressed mRNAs were involved in the regulation of a variety of biological processes, cellular components, and molecular functions. At the same time, the miRNA with differentially expressed miRNAs and their corresponding mRNAs were connected to further clarify the specific molecular mechanism of the pathological changes of myocarditis by constructing miRNA-mRNA network. It provides effective potential molecular targets for subsequent treatment and diagnosis.

Diagnostics of messenger ribonucleic acid (mRNA) severe acute respiratory syndrome-corona virus‑2 (SARS-CoV‑2) vaccination-associated myocarditis—A systematic review

Background

Objective

Methods

Results

Conclusion

Supplementary Information

A common oral pathogen Porphyromonas gingivalis induces myocarditis in rats

AIM

To evaluate whether Porphyromonas gingivalis (P. gingivalis) inoculation could induce cardiac remodelling in rats.

MATERIALS AND METHODS

The study was conducted on 33 Wistar rats, which were distributed in the following experimental groups: not inoculated; inoculated with 1 × 10⁸ CFU/ml of bacteria; inoculated with 3 × 10⁸ CFU/ml of bacteria. The animals were inoculated at baseline and on the 15th day of follow-up. Blood collection was performed at baseline and 60 min after each inoculation. At 29 days, the animals were subjected to echocardiography and at 30 days to haemodynamic studies before sacrificing them.

RESULTS

Impact of the bacteria was more evident in rats that received higher P. gingivalis concentration. Thus, 3 × 10⁸ CFU/ml of bacteria increased the rectal temperature and water content in the lung as well as myocardial necrosis and fibrosis. P. gingivalis induced the intensification of DNA fragmentation and increased the levels of malondialdehyde, oxidized proteins, and macrophage expression in the myocardium. These findings were associated with lower LV isovolumetric relaxation time, +dP/dt, -dP/dt, and higher end-diastolic pressure.

CONCLUSIONS

P. gingivalis bacteraemia is significantly associated with adverse cardiac remodelling and may play a biological role in the genesis of heart failure.

Eosinophilic Myocarditis: When Allergies Attack the Heart!

Eosinophilic myocarditis is a clinical condition whereby myocardial injury is mediated by eosinophilic infiltration. A number of underlying causes, including reactive, clonal, or idiopathic hypereosinophilic syndrome, may trigger eosinophilia. Disease presentation may vary from mild subclinical variants to fulminant myocarditis with thromboembolic complications, and in some cases, endomyocardial and valvular fibrosis may be seen. A detailed examination coupled with the use of multimodality imaging, and endomyocardial biopsy may help establish diagnosis. Treatment is aimed at symptomatic management and treating the underlying cause of eosinophilia, such as withdrawal of implicated drugs, antihelminthic therapy for infection, immunosuppression for autoimmune conditions, and targeted therapy with tyrosine kinase inhibitors in cases with clonal myeloid disorders.

Isolated Atrial Neutrophilic Myocarditis: A Rare Cause of Death and Potential "Blind Spot" for Postmortem Computed Tomography and Postmortem Examination

ABSTRACT

Myocarditis can focally or diffusely involve the myocardium and is associated with arrhythmia, cardiac failure, and sudden death. The majority of cases of myocarditis are lymphocytic in etiology, and neutrophilic myocarditis is relatively uncommon. Although reported in lymphocytic myocarditis, isolated/focal neutrophilic myocarditis of the atrium causing death is not reported in the postmortem literature, and its postmortem computed tomography correlation is not documented. We report a fatal case of isolated neutrophilic atrial myocarditis affecting only the left atrium in a 33-year-old woman presenting as a sudden unexpected death. Microscopy of the left atrium, a not commonly sampled area of the heart, showed florid neutrophilic myocarditis with the remaining right atrium, conduction system, and both ventricles uninvolved. Similar to previously reported fatal isolated atrial lymphocytic myocarditis, postmortem computed tomography was unable to detect any atrial abnormalities. This case highlights a potential "blind spot" for both routine postmortem imaging and examination.

Emerging Role of Cardiac Magnetic Resonance Imaging in Diagnosing Myocarditis: A Blunder or The Way To Get the Problem Sorted?

Acute myocarditis is a disease affecting the myocardial tissue, which is caused by infections, rheumatic diseases, especially sarcoidosis, or certain therapies. Its diagnosis may be difficult, owing to its variable clinical presentation. In this setting, cardiac magnetic resonance plays a pivotal role in detecting myocardial inflammation through qualitative, semiquantitative, and quantitative parameters, in particular with the new quantitative techniques such as T1 and T2 mapping, combined or not with late gadolinium enhancement evaluation. This is in accordance with the revised Lake Louise criteria. In this review, the emerging role of the new cutting-edge cardiac magnetic resonance imaging techniques in diagnosing myocarditis is extensively presented.

Autopsy Histopathologic Cardiac Findings in Two Adolescents Following the Second COVID-19 Vaccine Dose

CONTEXT

- Myocarditis in adolescents has been diagnosed clinically following the administration of the second dose of an mRNA vaccine for coronavirus disease 2019 (COVID-19).

OBJECTIVE

- To examine the autopsy microscopic cardiac findings in adolescent deaths that occurred shortly following administration of the second Pfizer-BioNTech COVID-19 dose to determine if the "myocarditis" described in these instances has the typical histopathology of myocarditis.

DESIGN

- Clinical and autopsy investigation of two teenage boys who died shortly following administration of the second Pfizer-BioNTech COVID-19 dose.

RESULTS

- The microscopic examination revealed features resembling a catecholamine-induced injury, not typical myocarditis pathology.

CONCLUSIONS

- The myocardial injury seen in these post-vaccine hearts is different from typical myocarditis and has an appearance most closely resembling a catecholamine-mediated stress (toxic) cardiomyopathy. Understanding that these instances are different from typical myocarditis and that cytokine storm has a known feedback loop with catecholamines may help guide screening and therapy.

Fulminant Giant Cell Myocarditis vs. Lymphocytic Myocarditis: A Comparison of Their Clinical Characteristics, Treatments, and Outcomes

Objectives: Fulminant myocarditis (FM) is a rapidly progressive and frequently fatal form of myocarditis that has been difficult to classify. This study aims to compare the clinical characteristics, treatments and outcomes in patients with fulminant giant cell myocarditis (FGCM) and fulminant lymphocytic myocarditis (FLM).

Methods and Results: In our retrospective study, nine patients with FGCM (mean age 47.9 ± 7.5 years, six female) and 7 FLM (mean age 42.1 ± 12.3 years, four female) patients confirmed by histology in the last 11 years were included. Most patients with FGCM and FLM were NYHA functional class IV (56 vs. 100%, p = 0.132). Patients with FGCM had significantly lower levels of high-sensitivity C-reactive protein [hs-CRP, 4.4 (2.0–10.2) mg/L vs. 13.6 (12.6–14.6) mg/L, P = 0.004, data shown as the median with IQR], creatine kinase-myoglobin [CK-MB, 1.4 (1.0–3.2) ng/ml vs. 14.6 (3.0–64.9) ng/ml, P = 0.025, median with IQR], and alanine aminotransferase [ALT, 38.0 (25.0–61.5) IU/L vs. 997.0 (50.0–3,080.0) IU/L, P = 0.030, median with IQR] and greater right ventricular end-diastolic diameter (RVEDD) [2.9 ± 0.3 cm vs. 2.4 ± 0.6 cm, P = 0.034, mean ± SD] than those with FLM. No differences were observed in the use of intra-aortic balloon pump (44 vs. 43%, p = 1.000) and extracorporeal membrane oxygenation (11 vs. 43%, p = 0.262) between the two groups. The long-term survival rate was significantly lower in FGCM group compared with FLM group (0 vs. 71.4%, p = 0.022). A multivariate cox regression analysis showed the level of hs-CRP (hazard ratio = 0.871, 95% confidence interval: 0.761–0.996, P = 0.043) was an independent prognostic factor for FM patients. Furthermore, the level of hs-CRP had a good ability to discriminate between patients with FGCM and FLM (AUC = 0.94, 95% confidence interval: 0.4213–0.9964).

Conclusions: The inflammatory response and myocardial damage in the patients with FGCM were milder than those with FLM. Patients with FGCM had distinctly poorer prognoses compared with those with FLM. Our results suggest that hs-CRP could be a promising prognostic biomarker and a hs-CRP level of 11.71 mg/L is an appropriate cutoff point for the differentiating diagnosis between patients with FGCM and FLM.

The histopathological spectrum of myocardial inflammation in relation to circumstance of death: a retrospective cohort study in clinical and forensic autopsies

Interpreting a myocardial inflammation as causal, contributory or as of no significance at all in the cause of death can be challenging, especially in cases where other pathologic and/or medico-legal findings are also present. To further evaluate the significance of myocardial inflammation as a cause of death we performed a retrospective cohort study of forensic and clinical autopsy cases. We revised the spectrum of histological inflammatory parameters in the myocardium of 79 adult autopsy cases and related these to the reported cause of death. Myocardial slides were reviewed for the distribution and intensity of inflammatory cell infiltrations, the predominant inflammatory cell type, and the presence of inflammation-associated myocyte injury, fibrosis, edema and hemorrhage. Next, the cases were divided over three groups, based on the reported cause of death. Group 1 (n = 27) consisted of all individuals with an obvious unnatural cause of death. Group 2 (n = 29) included all individuals in which myocarditis was interpreted to be one out of more possible causes of death. Group 3 (n = 23) consisted of all individuals in which myocarditis was reported to be the only significant finding at autopsy, and no other cause of death was found. Systematic application of our histological parameters showed that only a diffuse increase of inflammatory cells could discriminate between an incidental presence of inflammation (Group 1) or a potentially significant one (Groups 2 and 3). No other histological parameter showed significant differences between the groups. Our results suggest that generally used histological parameters are often insufficient to differentiate an incidental myocarditis from a (potentially) significant one.

Early application of extracorporeal membrane oxygenation for myocarditis with shock: a case report

The current therapy for myocarditis is immunosuppressive therapy. However, in rare cases in which patients do not respond to intervention, their condition can rapidly deteriorate to myocarditis with shock, which is characterized by extensive and diffuse lymphocyte infiltration in the myocardium. Most cases of myocarditis are caused by virus-mediated damage of cardiomyocytes, and its clinical manifestations are ventricular arrhythmia and hemodynamic disturbances. Extracorporeal membrane oxygenation is an effective intervention, which regulates hemodynamic stability and avoids systemic hypoperfusion. This intervention has been used to sustain hemodynamic stability in patients with myocarditis and shock. We report here early application of extracorporeal membrane oxygenation for successful treatment of a patient with myocarditis and shock.

Viral Myocarditis-From Pathophysiology to Treatment

The diagnosis of acute and chronic myocarditis remains a challenge for clinicians. Characterization of this disease has been hampered by its diverse etiologies and heterogeneous clinical presentations. Most cases of myocarditis are caused by infectious agents. Despite successful research in the last few years, the pathophysiology of viral myocarditis and its sequelae leading to severe heart failure with a poor prognosis is not fully understood and represents a significant public health issue globally. Most likely, at a certain point, besides viral persistence, several etiological types merge into a common pathogenic autoimmune process leading to chronic inflammation and tissue remodeling, ultimately resulting in the clinical phenotype of dilated cardiomyopathy. Understanding the underlying molecular mechanisms is necessary to assess the prognosis of patients and is fundamental to appropriate specific and personalized therapeutic strategies. To reach this clinical prerequisite, there is the need for advanced diagnostic tools, including an endomyocardial biopsy and guidelines to optimize the management of this disease. The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has currently led to the worst pandemic in a century and has awakened a special sensitivity throughout the world to viral infections. This work aims to summarize the pathophysiology of viral myocarditis, advanced diagnostic methods and the current state of treatment options.

Myocardial involvement in anti-phospholipid syndrome: Beyond acute myocardial infarction

Anti-phospholipid antibodies (aPL) are the serological biomarkers of anti-phospholipid syndrome (APS), an autoimmune disorder characterized by vascular events and/or pregnancy morbidity. APS is a unique condition as thrombosis might occur in arterial, venous or capillary circulations. The heart provides a frequent target for circulating aPL, leading to a wide variety of clinical manifestations. The most common cardiac presentation in APS, valvular involvement, acknowledges a dual etiology comprising both microthrombotic and inflammatory mechanisms. We describe the cases of 4 patients with primary APS who presented a clinically manifest myocardiopathy without epicardial macrovascular distribution. We propose that microthrombotic/inflammatory myocardiopathy might be an overlooked complication of high-risk APS. As extensively hereby reviewed, the literature provides support to this hypothesis in terms of anecdotal case-reports, in some cases with myocardial bioptic specimens. In aPL-positive subjects, microthrombotic/inflammatory myocardial involvement might also clinically manifest as dilated cardiomyopathy, a clinical entity characterized by ventricular dilation and reduced cardiac output. Furthermore, microthrombotic/inflammatory myocardial involvement might be subclinical, presenting as diastolic dysfunction. Currently, there is no single clinical or imaging finding to firmly confirm the diagnosis; an integrated approach including clinical history, clinical assessment, laboratory tests and cardiac magnetic resonance should be pursued in patients with suggestive clinical presentation.

Myocarditis and Pericarditis following COVID-19 Vaccination: Inequalities in Age and Vaccine Types

An increasing number of myocarditis/pericarditis incidences has been reported after coronavirus disease-19 (COVID-19) vaccination in adolescents and young adults. This study was designed to investigate the incidence rate of-and risk for-myocarditis and pericarditis following COVID-19 vaccination in the United States according to age and vaccine type. This study used the Vaccine Adverse Events Reporting System (VAERS) from 11 December 2020 to 13 August 2021. A population-based data mining approach was performed based on the reporting odds ratio (ROR). Adverse events of myocarditis and pericarditis following COVID-19 vaccination were rare, with an incidence rate of 5.98 (95% CI = 5.73-6.24) cases per million doses administered. The incidence rate was higher in adolescents and after the administration of the second dose of messenger RNA (mRNA) vaccines. Overall, two mRNA vaccines were significantly associated with increased risks for myocarditis/pericarditis (mRNA-1273 (Moderna): ROR = 2.91, 95% CI = 2.21-3.83; BNT162b2 (Pfizer-BioNTech): ROR = 5.37, 95% CI = 4.10-7.04) compared to all other vaccines from VAERS. The viral vector vaccine of Ad26.COV2.S (Janssen) was not associated with signals of myocarditis/pericarditis (ROR = 1.39; 95% CI = 0.99-1.97). This study found increased risks for myocarditis/pericarditis following mRNA COVID-19 vaccines. For patients at high risk for myocarditis/pericarditis or with myocardial injuries, the viral vector vaccine may be an alternative for consideration.

Myocarditis-induced Sudden Death after BNT162b2 mRNA COVID-19 Vaccination in Korea: Case Report Focusing on Histopathological Findings

We present autopsy findings of a 22-year-old man who developed chest pain 5 days after the first dose of the BNT162b2 mRNA vaccine and died 7 hours later. Histological examination of the heart revealed isolated atrial myocarditis, with neutrophil and histiocyte predominance. Immunohistochemical C4d staining revealed scattered single-cell necrosis of myocytes which was not accompanied by inflammatory infiltrates. Extensive contraction band necrosis was observed in the atria and ventricles. There was no evidence of microthrombosis or infection in the heart and other organs. The primary cause of death was determined to be myocarditis, causally-associated with the BNT162b2 vaccine.

Cardiovascular consequences of viral infections: from COVID to other viral diseases

Infection of the heart muscle with cardiotropic viruses is one of the major aetiologies of myocarditis and acute and chronic inflammatory cardiomyopathy (DCMi). However, viral myocarditis and subsequent dilated cardiomyopathy is still a challenging disease to diagnose and to treat and is therefore a significant public health issue globally. Advances in clinical examination and thorough molecular genetic analysis of intramyocardial viruses and their activation status have incrementally improved our understanding of molecular pathogenesis and pathophysiology of viral infections of the heart muscle. To date, several cardiotropic viruses have been implicated as causes of myocarditis and DCMi. These include, among others, classical cardiotropic enteroviruses (Coxsackieviruses B), the most commonly detected parvovirus B19, and human herpes virus 6. A newcomer is the respiratory virus that has triggered the worst pandemic in a century, SARS-CoV-2, whose involvement and impact in viral cardiovascular disease is under scrutiny. Despite extensive research into the pathomechanisms of viral infections of the cardiovascular system, our knowledge regarding their treatment and management is still incomplete. Accordingly, in this review, we aim to explore and summarize the current knowledge and available evidence on viral infections of the heart. We focus on diagnostics, clinical relevance and cardiovascular consequences, pathophysiology, and current and novel treatment strategies.

Myocarditis occurrence with cancer immunotherapy across indications in clinical trial and post-marketing data

Antibodies targeting the PD-1, PD-L1, and CTLA-4 immune checkpoint axis have been used in a variety of tumor types. They achieve anti-tumor activity through activating the patient’s own immune system to target immune response evading cancer cells. However, this unique mechanism of action may cause immune-related adverse events, irAEs. One of these irAEs is myocarditis which is associated with an alarming mortality rate. In this study we presented clinical cases of myocarditis from safety trial datasets submitted to the U.S. Food and Drug Administration, FDA. Additionally, we analyzed over fourteen million FDA Adverse Event Reporting System, FAERS, submissions. The statistical analysis of the FAERS data provided evidence of significantly increased reporting of myocarditis in patients administered immune checkpoint inhibitors alone, in combination with another immune checkpoint inhibitor, the kinase inhibitor axitinib, or chemotherapy, for all cancer types, when compared to patients administered chemotherapy. All combination therapies led to further increased reporting odds ratios of myocarditis. We further analyzed the occurrence of myocarditis by stratifying the reports into sub-cohorts based on specific cancer types and treatment/control groups in major cancer immunotherapy efficacy trials and confirmed the observed trend for each cohort.

Immune Checkpoint Inhibitors Mediated Lymphocytic and Giant Cell Myocarditis: Uncovering Etiological Mechanisms

The advent of immune checkpoint inhibitors (ICIs) has revolutionized the field of oncology, but these are associated with immune related adverse events. One such adverse event, is myocarditis, which has limited the continued immunosuppressive treatment options in patients afflicted by the disease. Pre-clinical and clinical data have found that specific ICI targets and precipitate distinct myocardial infiltrates, consistent with lymphocytic or giant cell myocarditis. Specifically, it has been reported that CTLA-4 inhibition preferentially results in giant cell myocarditis with a predominately CD4+ T cell infiltrate and PD-1 inhibition leads to lymphocytic myocarditis, with a predominately CD8+ T cell infiltrate. Our manuscript discusses the latest literature surrounding ICI pathways and targets, while detailing proposed mechanisms behind ICI mediated myocarditis.

Immune checkpoint inhibitor-induced myocarditis in cancer patients: a case report and review of reported cases

BACKGROUND

Immune checkpoint inhibitor (ICI) induced myocarditis is a rare, severe, and often fatal adverse event. Evidence to guide appropriate immunosuppressive therapy is scarce. We present a case of ICI-induced myocarditis and a review of ICI-induced myocarditis cases to determine the most effective immunosuppressive therapeutic strategy for ICI-induced myocarditis.

METHODS

A systematic search of PubMed was carried out for treatment of ICI-induced myocarditis. Reference lists from identified articles were manually reviewed for additional cases.

RESULTS

A total of 87 cases with ICI-induced myocarditis were identified. The majority were melanoma (n = 39), lung cancer (n = 19), renal cell cancer (n = 10), and thymoma cancer patients (n = 4). In 38 (44%) cases, patients received high-dose steroid treatment only. A total of 49 (56%) cases were treated with immunosuppressive agents other than steroid; a total of 13 different immunosuppressive agents were used, including alemtuzumab or abatacept. The median time to onset of symptoms after initiation of ICI was 16 days (range, 1-196 days); cardiotoxic symptoms developed after 2 cycles of ICI (range, 1-13 cycles). A total of 48% of cases were fatal. In cases treated with high-dose steroids only vs. cases treated with other immunosuppressive agents, fatality was 55% and 43% respectively. In 64 out of the 87 cases, tumor control was not described. In patients treated with high-dose steroids only, two patients had stable disease as best tumor response; in patients treated with other immunosuppressive agents, one complete response, one partial response and seven stable disease were noted as best tumor response. Overall, 11 studies were at low risk of bias (12.6%), 38 at moderate risk of bias (43.7%) and 38 at high risk of bias (43.7%).

CONCLUSION

Immune checkpoint inhibitor induced myocarditis is a serious and often fatal adverse event. High-dose prednisolone, alemtuzumab or abatacept are all possible treatments options for ICI-induced myocarditis, whereas infliximab increases the risk of death from cardiovascular causes, and should be avoided. Further research is needed.

Monitoring for myocarditis during treatment initiation with clozapine

OBJECTIVE

Clozapine use is associated with myocarditis. In this study, we investigated what clinical signs and symptoms, and/or laboratory test(s), alert clinicians to presumptive myocarditis (PrMy) most accurately and at the earliest time point. We also investigated the incidence of PrMy during the initial exposure to clozapine versus in patients restarted on clozapine after extended interruption of prior prolonged treatment.

METHODS

100 patients admitted to state psychiatric hospital started on clozapine were recruited into the study. 76 patients were treated with clozapine for the first time and 24 patients were restarts. Creatine kinase (CK), troponin I (TROP), eosinophil count (EOS), and C-reactive protein (CRP) were obtained at baseline and weeks 1, 2, 3, and 4. Descriptive statistics were calculated for demographic and clinical variables. Student's t test and chi-squared test were used to compare means and proportions between initial exposure and restart groups.

RESULTS

Clinical features and laboratory tests suggestive of PrMy were seen in 4 patients (5.3%) in initial exposure group and none in restart group. 3.5% of TROP levels were abnormal in initial exposure group and no abnormal levels were found in the restart group. 30% and 46% of CK, 23% and 39% of CRP, and 14% and 23% of EOS were abnormal in initial exposure group and restart groups, respectively.

CONCLUSIONS

PrMy was common (5.3%) during clozapine initiation. Prospective management through serial laboratory monitoring with weekly TROP levels was sensitive enough to allow for timely clozapine discontinuation.