Myocarditis

SARS-CoV-2 damages cardiomyocyte mitochondria and implicates long COVID-associated cardiovascular manifestations

INTRODUCTION

With the COVID-19 pandemic becoming endemic, vigilance for Long COVID-related cardiovascular issues remains essential, though their specific pathophysiology is largely unexplored.

OBJECTIVES

Our study investigates the persistent cardiovascular symptoms observed in individuals long after contracting SARS-CoV-2, a condition commonly referred to as "Long COVID", which has significantly affected millions globally.

METHODS

We meticulously describe the cardiovascular outcomes in five patients, encompassing a range of severe conditions such as sudden cardiac death during exercise, coronary atherosclerotic heart disease, palpitation, chest tightness, and acute myocarditis.

RESULTS

All five patients were diagnosed with myocarditis, confirmed through endomyocardial biopsy and histochemical staining, which identified inflammatory cell infiltration in their heart tissue. Crucially, electron microscopy revealed widespread mitochondrial vacuolations and the presence of myofilament degradation within the cardiomyocytes of these patients. These findings were mirrored in SARS-CoV-2-infected mice, suggesting a potential underlying cellular mechanism for the cardiac effects associated with Long COVID.

CONCLUSION

Our findings demonstrate a profound impact of SARS-CoV-2 on mitochondrial integrity, shedding light on the cardiovascular implications of Long COVID.

Clinical Characteristics and Outcomes of Acute Myocarditis: An Analysis of Korean Multicenter Registry

BACKGROUND AND OBJECTIVES

Data are limited on the clinical manifestations and outcomes of acute myocarditis from a large-scale registry. We investigated acute myocarditis's clinical characteristics and prognosis from a large-scale, multi-center registry in the Republic of Korea.

METHODS

We collected data from seven hospitals between 2001 and 2021. Clinical variables and outcomes during the index hospitalization and follow-up periods were analyzed. We also evaluated inter-center and temporal differences in diagnostic and treatment patterns.

RESULTS

Eight hundred forty-one patients diagnosed with acute myocarditis were included. Common symptoms included chest pain (60.4%), followed by fever or myalgia (46.3%), and dyspnea (45.7%). Fulminant myocarditis occurred in 421 (50.1%), with 217 requiring extracorporeal membrane oxygenation (ECMO) support. Endomyocardial biopsy (EMB) was performed in 276 (32.8%) patients, and biopsy-proven diagnosis was made in 234 (27.8%). Based on the EMB results, lymphocytic myocarditis was the predominant form (69.6%), followed by eosinophilic (13.8%) and giant cell myocarditis (1.4%). Eighty-three in-hospital (9.9%) and 16 (1.9%) additional mortality during the follow-up occurred. An increase in the use of EMB, cardiac imaging, and immunosuppressive therapy was noted over time, but in-hospital mortality remained unchanged. Remarkable variations in diagnosis and treatment were observed across different centers.

CONCLUSIONS

This study unveiled clinical features of acute myocarditis in the Republic of Korea, including a high incidence of fulminant myocarditis and complex cases requiring ECMO. Given the considerable inter-center variation in diagnostic and treatment patterns and prognosis, protocolized future trials are needed to clarify diagnosis and treatment in patients with acute myocarditis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05933902.

Friend or foe of tripartite motif-containing protein 21 in cardiovascular disease: A review

As an E3 ubiquitin ligase and an Fc receptor, tripartite motif-containing protein 21 (TRIM21) plays a crucial role in immune defense, signal transduction, and cellular regulation. TRIM21 is widely expressed in various tissues, but it is particularly abundant in cardiovascular tissues and is involved in the pathogenesis of various cardiovascular diseases (CVDs). However, although TRIM21 is involved in the regulation of several key molecular pathways in the immune system, its specific role in CVD remains unclear. In this review, we comprehensively summarize the regulatory role of TRIM21 in signaling pathways and discuss the function of TRIM21 in CVD, to provide a systematic understanding of this important protein in CVD and offer insights for further research into the pathogenesis of CVD and its potential applications.

Global, regional, and national burden of myocarditis and its attributable risk factors in 204 countries and territories from 1990 to 2021: updated systematic analysis

Background

Comprehending the current epidemiological trends and risk factors of myocarditis is crucial for guiding future targeted prevention and treatment strategies.

Methods

Utilizing data from the Global Burden of Diseases, Injuries, and Risk Factors Study 2021, we conducted a secondary analysis of the incidence, prevalence, death, and disability-adjusted life years (DALYs) of myocarditis by sex, age group and socio-demographic index (SDI) across 204 countries and territories from 1990 to 2021. And non-optimal temperatures, defined as same-day exposure to ambient temperatures deviating from the minimum death risk threshold, were identified as risk-factors for myocarditis-related death and DALYs.

Results

From 1990 to 2021, the global prevalence of myocarditis increased from 320,623 (95% uncertainty interval: 268,557 to 371,912) to 505,030 (432,295 to 587,819). Concurrently, the age-standardized prevalence rate (ASPR) per 100,000 people also saw a slight increase (no statistical significance) from 6.35 (5.37 to 7.36) to 6.41 (5.48 to 7.44). However, the age-standardized incidence rate (ASIR), age-standardized death rate (ASDR) and age-standardized DALY rate (ASYR) exhibited declines, with estimated annual percentage changes of -0.20 (-0.23 to -0.17), -1.37 (-1.81 to -0.92) and -1.71 (-1.95 to -1.46), respectively. SDI quintile analysis showed that the high SDI quintile had the highest ASIR and ASPR, while the middle and high-middle SDI quintiles exhibited the highest ASDR and ASYR. Furthermore, the burden of myocarditis was notably high among males and older adult populations. Non-optimal temperature, particularly low temperature, emerged as a key risk factor for myocarditis-related ASDR and ASYR.

Conclusion

Although the ASIR, ASDR and ASYR for myocarditis exhibited decreasing trends from 1990 to 2019, further efforts are needed to develop targeted public health strategies, especially for low SDI regions, males, and older adult populations.

The occurrence of and risk factors for depressive symptomatology in myocarditis survivors: a cross-sectional survey-based study using machine learning

Background

The frequency and impact of depressive symptoms in myocarditis survivors are poorly understood.

Objectives

We conducted a cross-sectional study to identify risk factors and the relative importance of each for predicting clinically significant depressive symptomatology in myocarditis survivors.

Methods

Participants completed an electronic survey assessing sociodemographic, general health, and myocarditis-related variables, as well as self-reported cardiac symptoms and personal and family mental health history. Participants also completed the Center for Epidemiologic Studies Depression Scale (CES-D), Beck Anxiety Inventory (BAI), revised Impact of Events Scale (IES-R), and other validated measures of social support, quality of life, resiliency, childhood adversity, treatment distress, and somatic symptom burden. Clinically significant depressive symptomatology was defined as a CES-D total score ≥ 16. We used supervised machine learning to examine which and how well psychosocial and other types of variables predicted clinically significant depressive symptomatology in myocarditis survivors. Finally, we calculated the variable importance for each variable from the trained models and examined the rank ordering of predictors.

Results

Ninety-six of 113 respondents (85.0%) with complete survey data were included in the analyses. Forty-three (44.8%) respondents had clinically significant depressive symptomatology. When predicting depressive symptomatology, random forests achieved a mean AUC of 0.91 (95% CI 0.87-0.95) and a significantly higher accuracy than that of the null information rate (0.84 vs 0.55, p < 0.005), with correspondingly high sensitivity (0.84) and specificity (0.85). Emotional wellbeing, quality of life, history of depression, anxiety, and resilience were the top predictors in variable importance analyses, ahead of self-reported cardiovascular symptoms, other myocarditis-related variables, and family history of depression.

Conclusions

Myocarditis survivors are at high risk for clinically significant depressive symptomatology. Psychosocial factors that are measurable in routine practice may be more predictive of significant depressive symptomatology than demographics, family history, or self-reported cardiovascular symptoms.

Revisiting Secondary Dilative Cardiomyopathy

Secondary dilated cardiomyopathy (DCM) refers to left ventricular dilation and impaired systolic function arising from identifiable extrinsic causes, such as ischemia, hypertension, toxins, infections, systemic diseases, or metabolic disorders. Unlike primary DCM, which is predominantly genetic, secondary DCM represents a diverse spectrum of pathophysiological mechanisms linked to external insults on myocardial structure and function. The increasing prevalence of conditions such as alcohol use disorder, chemotherapy-induced cardiotoxicity, and viral myocarditis underscores the need for heightened awareness and early recognition of secondary DCM. A comprehensive analysis of clinical trial data and observational studies involving secondary dilative cardiomyopathy was conducted, with a focus on mortality, symptom relief, and major adverse events. A systematic literature review was performed using databases, including PubMed, Embase, and ClinicalTrials.gov, following PRISMA guidelines for study selection. Data were extracted on patient demographics, etiology of dilation, trial design, outcomes, and follow-up duration. Advances in diagnostic modalities have refined the ability to identify underlying causes of secondary DCM. For example, high-sensitivity troponin and cardiac magnetic resonance imaging are pivotal in diagnosing myocarditis and differentiating it from ischemic cardiomyopathy. Novel insights into toxin-induced cardiomyopathies, such as those related to anthracyclines and immune checkpoint inhibitors, have highlighted pathways of mitochondrial dysfunction and oxidative stress. Treatment strategies emphasize the management of the causing condition alongside standard heart failure therapies, including RAAS inhibitors and beta-blockers. Emerging therapies, such as myocardial recovery protocols in peripartum cardiomyopathy and immune-modulating treatments in myocarditis, are promising in reversing myocardial dysfunction. Secondary DCM encompasses a heterogeneous group of disorders that require a precise etiological diagnosis for effective management. Timely identification and treatment of the underlying cause, combined with optimized heart failure therapies, can significantly improve outcomes. Future research focuses on developing targeted therapies and exploring the role of biomarkers and precision medicine in tailoring treatment strategies for secondary DCM.

Macrophages of the Heart: Homeostasis and Disease

Cardiac macrophages (CMs) are the most abundant immune cell type in the heart. They are critical for maintaining cardiac homeostasis and in the orchestration of immune responses to ischemic and non-ischemic cardiomyopathies. Their functions are highly heterogeneous and regulated by their tissue microenvironment. CMs have high plasticity, which allows them to perform various functions in the myocardium to bring about homeostasis within the cardiovascular system (CVS). CMs also play critical roles in coronary development and angiogenesis, tissue repair and remodeling, cardiac conduction and in the clearance of necrotic and apoptotic cells. However, there is a paucity of studies on the biology of cardiac macrophages in both steady state and disease, especially, in humans. In this review, we discuss the multifaceted roles of CMs in the heart, focusing on their ontogeny, homeostatic functions and immunological responses during inflammation and reparative processes post-injury. We highlight the heterogeneity of CMs in their ontogeny, phenotypes and functions as well as their roles in the pathogenesis of pathological conditions such as myocarditis, myocardial fibrosis and heart failure. Understanding the unique characteristics of cardiac macrophages in the cardiac milieu is critical for the development of macrophage-specific therapeutic interventions to alleviate the global burden of cardiovascular disease (CVD). Therefore, future studies should focus on further improving the understanding of the biology of cardiac macrophages to harness their potential as therapeutic targets for cardiovascular disorders.

Effects of Cardiac Remodeling and Altered Mechanics on Cardiac Outcomes in Fulminant Myocarditis in Children: Insight from a Longitudinal Pilot Study

Fulminant presentations of acute myocarditis can predict cardiac functional and patient outcomes. This longitudinal study compared pediatric cohorts with fulminant Multisystem Inflammatory Syndrome-related myocarditis (MISCM) vs non-COVID-19 viral myocarditis (VM) to test the hypothesis that the adverse left ventricular (LV) remodeling rather than the phenotype of presentation predicts clinical outcomes. This is a retrospective analysis of 54 children with MISCM (age 6 ± 4 years, weight 32.5 ± 24.6 kg, male 44%) and 26 children with VM (age 3.8 ± 4.8 years, weight 17.7 ± 17.7 kg, male 56%) on hospitalization and one-year follow-up. VM patients exhibited acute LV remodeling, but MISC patients did not (LV end-diastolic dimension z score 2.05 ± 2.50 vs 0.04 ± 1.10, p = 0.00). Compared to the MISCM, VM patients had severe LV systolic and diastolic dysfunction (ejection fraction 54.6% vs 39.9%, four-chamber longitudinal strain - 15.6% vs - 8.7%, and left atrial strain 25.5% vs 13.9% p = 0.000), increased need for mechanical circulatory support (39% vs 7%), 2 mortalities, one cardiac transplant, and stage C heart failure in the 17 survivors at discharge. Ejection fraction normalized but abnormal segmental four-chamber longitudinal strain persisted in both cohorts with most VM patients remaining on anti-failure treatment at one-year follow-up. Inflammation-mediated acute LV remodeling rather than the phenotype of presentation may determine LV function and patient outcomes. Non-invasive imaging can play a useful role in the assessment of the mechanism of LV remodeling and defining the trajectory of LV function and cardiac outcomes.

Multifaceted roles of neutrophils in cardiac disease

Neutrophils, the most abundant leukocytes in human blood, have long been recognized as critical first responders in the innate immune system's defense against pathogens. Some of the more notable innate antimicrobial properties of neutrophils include generation of superoxide free radicals like myeloperoxidase, production of proteases that reshape the extracellular matrix allowing for easier access to infected tissues, and release of neutrophil extracellular traps, extruded pieces of DNA that ensnare bacterial and fungi. These mechanisms developed to provide neutrophils with a vast array of specialized functions to provide the host defense against infection in an acute setting. However, emerging evidence over the past few decades has revealed a far more complex and nuanced role for these neutrophil-driven processes in various chronic conditions, particularly in cardiovascular diseases. The pathophysiology of cardiac diseases involves a complex interplay of hemodynamic, neurohumoral, and inflammatory factors. Neutrophils, as key mediators of inflammation, contribute significantly to this intricate network. Their involvement extends far beyond their classical role in pathogen clearance, encompassing diverse functions that can both exacerbate tissue damage and contribute to repair processes. Here, we consider the contributions of neutrophils to myocardial infarction, heart failure, cardiac arrhythmias, and nonischemic cardiomyopathies. Understanding these complex interactions is crucial for developing novel therapeutic strategies aimed at modulating neutrophil functions in these highly morbid cardiac diseases.

Global, regional and national epidemiology of myocarditis: health inequalities, risk factors and forecasted burden based on the Global Burden of Disease Study 2021

BACKGROUND

Myocarditis is a global epidemic that causes various medical conditions associated with an increased incidence and death numbers. This study aimed to investigate the trends in myocarditis-associated incidence, mortality, and disability-adjusted life-years (DALYs) with health inequalities, risk factors, and predict the disease burden, thereby mitigating the health hazards of myocarditis.

METHODS

This was a modelling study that used data from the Global Burden of Diseases 2021, from which myocarditis was included in the analysis. Incidence, death, DALYs, age-standardised incidence rate (ASIR), age-standardised mortality rate (ASMR), age-standardised DALYs rate (ASDR), cases change, corresponding estimated annual percentage change (EAPC), Slope Inequality of Index (SII) and Concentration Index were analysed.

RESULTS

From 1990 to 2021, incidence and death cases increased by 66.88% and 45.94%, respectively. The myocarditis-associated incidence and death cases increased in all five sociodemographic index (SDI) regions. Among the five SDI regions, the High SDI region had the highest myocarditis-associated ASIR with the least ASMR and ASDR in 2021. Regionally, Central Asia had the largest increase in EAPC of ASIR, ASMR and ASDR. Among 204 countries, Japan had the highest ASIR in 2021 and Romania had the highest ASMR and ASDR. Between 1990 and 2021, the SII and Concentration Index for DALYs have shown declining trends. The extreme temperatures were major contributors to the burden of myocarditis during 1990-2021. The projections suggested that the myocarditis-related global number of new cases and death would increase over the next 15 years. There may be upward trends in people of 15+of incidence number and 40+of death and DALYs number.

CONCLUSIONS

Myocarditis is an increasing global health challenge with rising incidence and death. Management of extreme temperatures remains a major challenge. The number of incidence, death and DALYs in different age groups would continue to grow over the next 15 years. Therefore, measures should be taken to target risk factors and high-risk groups.

Metabolic Profiling Reveals Diagnostic Biomarkers for Distinguishing Myocarditis From Acute Myocardial Infarction

Background: Distinguishing between myocarditis (MC) and acute myocardial infarction (AMI) in the early stages is crucial due to their similar symptoms yet vastly different treatment protocols. This study seeks to utilize metabolomics techniques to differentiate between MC and AMI. Methods: Plasma samples from 15 patients with MC and 12 patients with AMI were collected. Metabolic profiles of plasma from the two groups of patients were obtained using ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS), identifying metabolites with significant differences. Results: We identified 30 significantly different metabolites in both diseases. In patients with MC, 17 metabolites were upregulated, including 5-hydroxy-L-tryptophan and LysoPC (18:2(9Z,12Z)), while 13 metabolites were downregulated, such as 11-cis-retinol, L-glutamate, and hydroxynicotinic acid. KEGG enrichment analysis revealed that the altered metabolites were enriched in tryptophan metabolism, linoleic acid metabolism, primary bile acid biosynthesis, nitrogen metabolism, and retinol metabolism. Biomarker analysis via receiver-operating characteristic curves highlighted 11-cis-retinol as the predominant biomarker, with an AUC value of 0.917. Conclusions: In conclusion, patients experiencing AMI and MC undergo significant metabolic reprogramming. Metabolites exhibiting abnormal expression in peripheral blood hold diagnostic value for distinguishing between AMI and MC in clinical settings. 11-cis-retinol proved to be the pivotal biomarker for AMI, potentially aiding in the development of a robust predictive model for distinguishing between MC and AMI in clinical settings.

The mortality of myasthenia gravis with myocarditis: A single-center retrospective study

BACKGROUND

While numerous studies have investigated the onset features of myasthenia gravis (MG) complicated with myocarditis, there are few articles focusing on the prognosis of patients with both diseases. This study aims to examine mortality in patients with MG who also have myocarditis, and to summarize the clinical characteristics of deceased patients with both conditions.

RESULTS

A total of 91 patients with MG were included in our study, of which 19 (20.9 %) were diagnosed with myocarditis. Shorter MG duration, thymoma, history of myasthenia crisis (MC) and use of immune checkpoint inhibitors (ICIs) were risk factors for developing myocarditis in MG patients. Among the 13 myocarditis-MG patients who did not receive ICIs, 11(84.6 %) had thymoma and 5 (71.4 %) of the 7 tested were positive for titin-IgG. In all myocarditis-MG patients, 11 (57.9 %) died from myocarditis (average age 51 ± 18 years), with 9 (81.8 %) having thymoma and 5 (45 %) having a history of myasthenia crisis. Compared to the mortality rates of MC patients (16.1 %) and the general MG patients (1.8 %), the mortality rate of myocarditis-MG patients is significantly higher.

CONCLUSIONS

The study highlights that MG patients with myocarditis face a significantly increased risk of mortality. Thymoma and a history of MC were identified as potential risk factors for mortality, irrespective of prior ICI use.

Epidemiological Analysis of the Decline of Myocarditis Burden - China, 1992-2021

What is already known about this topic?

Myocarditis is a prevalent cardiovascular condition that can lead to severe complications. The number of patients with myocarditis, new cases, and deaths in China has been on an upward trend over the years, causing a certain disease burden.

What is added by this report?

The overall burden of myocarditis in China is on a downward trend; however, the age-standardized mortality rate (ASMR) and age-standardized disability-adjusted life years (DALYs) rate remain higher than the global average. The age-standardized incidence rate (ASIR), ASMR and age-standardized DALYs rate were higher in men than in women. Individuals younger than 5 years or older than 70 years, the period from 2002-2016, and birth cohort earlier than 1957 were identified as risk factors for myocarditis-related mortality.

What are the implications for public health practices?

We should still prioritize the prevention and treatment of myocarditis. It is recommended that primary and secondary prevention efforts focus on individuals younger than 5 years, older than 70 years, and males, with an emphasis on proactive health education and management.

Anti-RNApol3-Associated myocarditis: an emerging disease linking autoimmunity and infection

BACKGROUND

Fulminant myocarditis (FM) is a severe condition primarily triggered by viruses. Anti-RNA polymerase III autoantibodies (RNApol3) which are typically found in patients with severe systemic sclerosis, have been reported in patients with influenza-related FM. Our objective is to provide additional insight into RNApol3-associated FM.

METHODS

We retrospectively included all patients admitted to our institution between January 2013 and June 2023 with acute myocarditis and positive serum RNApol3. We compared their characteristics, etiologies, and outcomes with those of a cohort of RNApol3 negative acute myocarditis.

RESULTS

Twenty-nine RNApol3-positive patients, comprising 83% females with a mean age of 39 ± 12 years, were included in this study. Each patient was admitted to the intensive care unit at least once and 11 (38%) relapsed. Triggers included influenza virus in 55% and SARS-CoV-2 virus in 48% of cases. The lowest left ventricular ejection fraction was 10 [5-10] % and the highest troponin value was 82 [22-360] times the ULN. Patients required dobutamine (94%), veno-arterial extracorporeal membrane oxygenation (85%) and pericardiocentesis (38%). At the last follow-up, 76% of patients were still alive, while 7% had undergone cardiac transplantation, and 3% required a left ventricular assist device. Compared to RNApol3-negative cases, RNApol3-positive myocarditis was associated with female gender, fulminant evolution, tamponade, a higher likelihood of being caused by a proven viral infection, and a higher rate of relapse.

CONCLUSION

RNApol3-associated myocarditis is an emerging disease linking autoimmunity and infection and a unique cause of acquired, pathogen-specific, organ-specific immunodeficiency. RNApol3 should be screened in all cases of FM, especially in young women infected by RNA viruses. The risk of FM in RNApol3-positive systemic sclerosis needs further investigation.

Neurogenic differentiation 2 promotes inflammatory activation of macrophages in doxorubicin-induced myocarditis via regulating protein kinase D

BACKGROUND

Although it has been established that protein kinase D (PKD) plays a crucial role in various diseases, its precise role in myocarditis remains elusive.

METHODS

To investigate PKD's involvement in myocarditis, we established a mouse model of myocarditis using doxorubicin (DOX) to assess cardiac function, observe pathological changes, and quantify inflammatory cytokine levels in heart tissues. Additionally, macrophages were isolated from heart tissues of both control and DOX-treated groups to assess PKD expression and inflammatory cytokines in these macrophages. We explored the molecular mechanism of Neurogenic Differentiation 2 (NeuroD2) in myocarditis by utilizing NeuroD2 overexpression plasmids and NeuroD2 small interfering RNA (siRNA). Furthermore, we conducted dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays to investigate the interaction between NeuroD2 and PKD.

RESULTS

We observed significant upregulation of PKD in macrophages and heart tissues induced by DOX. The administration of a PKD inhibitor reduced inflammatory cytokine levels, improved cardiac function, and mitigated pathological changes in myocarditis-afflicted mice. Mechanistically, we found upregulated expression of NeuroD2 in both macrophages and heart tissues exposed to DOX. NeuroD2 could directly target PKD, enhancing the NLRP3/NF-κB signaling pathway and exacerbating macrophage inflammation.

CONCLUSIONS

Our study demonstrates that NeuroD2 can directly bind to the PKD promoter, potentially promoting inflammatory activation of macrophages in DOX-induced myocarditis via the NLRP3/NF-κB pathway. This suggests that the NeuroD2/PKD axis may hold promise as a potential therapeutic approach for treating DOX-induced myocarditis.

Macrophage-derived SPP1 exacerbate myocardial injury by interacting with fibroblasts in viral myocarditis

BACKGROUND

Viral myocarditis (VMC) is an inflammatory myocardial condition triggered by viral infections which involves pathogenic-related damage and immune-mediated damage. However, the precise immunopathogenic mechanisms underlying VMC remain elusive.

METHODS

We performed single-cell RNA sequencing on mouse hearts during the acute phase of CVB3-induced VMC. After manually annotating cell types, functional analyses of macrophage were performed by cell ratio changes, customized gene set module scoring and CellPhoneDB. Utilizing indirect co-culture experiments in vitro, the effects of macrophage-derived SPP1 on cardiac fibroblasts were investigated. Depletion of macrophages and inhibition of SPP1 expression in mice were carried out to study the effects of macrophage-derived SPP1 on cardiac function, inflammation levels, and myocardial injury in mice with VMC.

RESULTS

Our data revealed that macrophages are the major immune cells which infiltrate the heart during the acute phase of VMC, particularly a macrophage subpopulation which highly expresses Spp1 (Spp1+ macrophages) and exhibited characteristics of peripheral blood monocytes. Spp1+ macrophages communicate extensively with fibroblasts during VMC, and that SPP1 promotes fibroblast conversion to an inflammatory phenotype with high Ccl2/Ccl7 expression. This in turn increases monocyte chemotaxis to the heart. Besides, a partial depletion of macrophages in the early stages of VMC attenuated myocardial inflammation and myocardial injury in mice. Inhibition of SPP1 reduced cardiac macrophage infiltration, attenuated myocardial inflammation, and improved cardiac function in VMC mice.

CONCLUSION

Our findings suggested that Spp1+ macrophages could self-recruit, and macrophage-derived SPP1 exacerbated myocardial immune injury by promoting high Ccl2/Ccl7 expression in fibroblasts. Our study advances understandings of VMC pathogenesis, and provides novel insight into potential immunotherapies for VMC.

Immune Checkpoint Inhibitor-induced Myocarditis: A Case Report of Complete Heart Block and Challenges in a Patient on Pembrolizumab

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment by modulating immune responses, leading to enhanced anti-tumor activity. ICIs, including agents targeting cytotoxic T-lymphocyte antigen 4, programmed cell death 1, and programmed cell death ligand, are now widely used in various malignancies, either as monotherapy or in combination with chemotherapy, radiotherapy, or targeted therapies. However, ICIs are associated with immune-related adverse events, affecting multiple organ systems, with myocarditis emerging as a rare but potentially fatal complication. We present a 67-year-old man with a history of prostate and renal cell carcinoma treated with pembrolizumab and lenvatinib, who developed myocarditis secondary to ICI therapy. The patient initially presented with generalized fatigue and bradycardia, later progressing to more severe symptoms, including sinus bradycardia and elevated troponin levels. An electrocardiogram revealed a sinus rhythm with first-degree atrioventricular block, non-specific intraventricular conduction delay, and elevated high-sensitivity troponin levels progressively increasing to 50,000 pg/mL. A comprehensive diagnostic workup ruled out ischemic causes, leading to the diagnosis of ICI-induced myocarditis. The patient was treated with high-dose corticosteroids, intravenous immunoglobulin, and temporary pacemaker insertion, resulting in clinical improvement. This case highlights the need for vigilance and prompt intervention in patients receiving ICI therapy, as early recognition and treatment of myocarditis are crucial to optimizing patient outcomes in this high-risk population.

Analysis of Cytokine Profiles in Pediatric Myocarditis Multicenter Study

Acute myocarditis (AM) is an inflammatory disease of the heart muscle that can progress to fulminant myocarditis (FM), a severe and life-threatening condition. The cytokine profile of myocarditis in children, especially in relation to fulminant myocarditis, is not well understood. This study aims to evaluate the cytokine profiles of acute and fulminant myocarditis in children. Pediatric patients diagnosed with myocarditis were included in the study. Cytokine levels were measured using a multiplexed fluorescent bead-based immunoassay. Statistical analysis was performed to compare patient characteristics and cytokine levels between FM, AM, and healthy control (HC) groups. Principal component analysis (PCA) was applied to cytokine groups that were independent among the FM, AM, and HC groups. The study included 22 patients with FM and 14 with AM patients. We identified four cytokines that were significantly higher in the FM group compared to the AM group: IL1-RA (p = 0.002), IL-8 (p = 0.005), IL-10 (p = 0.011), and IL-15 (p = 0.005). IL-4 was significantly higher in the AM group compared to FM and HC groups (p = 0.006 and 0.0015). PDGF-AA, and VEGF-A were significantly lower in the FM group than in the AM group (p = 0.013 and <0.001). Similar results were obtained in PCA. Cytokine profiles might be used to differentiate pediatric FM from AM, stratify severity, and predict prognosis. The targeted therapy that works individual cytokines might provide a potential treatment for reducing the onset of the FM and calming the condition, and further studies are needed.

Clinical Characteristics and Outcomes of Takotsubo Syndrome Patients with Gastrointestinal Diseases: A Systematic Review

Background

Takotsubo syndrome (TTS) is identified by its acute and transient impairment of left ventricular systolic function. Although recent research has highlighted occurrences of TTS among individuals with gastrointestinal diseases (GI diseases), comprehensive and systematic investigations focusing on this patient demographic are still scarce.

Methods

This retrospective study analyzed case reports and series that documented an association between gastrointestinal diseases (GI diseases) and Takotsubo syndrome (TTS). We conducted comprehensive searches across PubMed, Embase, and the Cochrane Database to identify relevant cases.

Results

In patients with gastrointestinal-induced Takotsubo syndrome (GI-TTS), the primary reasons for admission were pancreatitis (15.48 %), liver failure (10.71 %), bowel obstruction (5.95 %) and liver cirrhosis (5.95 %). It is noteworthy that the main triggers for Takotsubo syndrome are surgeries related to gastrointestinal diseases (29.76 %), including liver transplantation (15.48 %) and cholecystectomy (2.38 %). Dyspnea (45.71 %) was the most common symptom, followed by abdominal pain (35.71 %) and chest pain (34.29 %). The apical type was the most frequent TTS variant (81.25 %). Compared with the All-TTS cohort, GI-TTS patients were younger, and had a lower proportion of women (69.05 % vs. 89.77 %, P < 0.001). GI-TTS patients had higher ventilation use and lower usage of β-blockers, ACEI/ARBs, aspirin, and statins, while catecholamine use was more prevalent.

Conclusions

The study underscores the potential of gastrointestinal diseases and their treatments to trigger TTS, often presenting atypical clinical features compared to TTS of all types. Given these differences, an elevated level of clinical vigilance is imperative for the timely diagnosis of TTS in patients with gastrointestinal conditions.

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.

Incremental Prognostic Value of Left Atrial Strain in Patients With Suspected Myocarditis and Preserved Left Ventricular Ejection Fraction

BACKGROUND

Analysis of left atrial (LA) strain and left atrioventricular coupling index (LACI) have prognostic value in cardiovascular diseases. However, the prognostic value of LA strain and LACI in patients with suspected myocarditis and preserved left ventricular ejection fraction (LVEF) is unclear.

PURPOSE

To investigate the prognostic value of LA strain and LACI in patients with suspected myocarditis and preserved LVEF in comparison with conventional MRI outcome predictors.

STUDY TYPE

Retrospective.

POPULATION

One hundred sixty-five patients with clinically suspected myocarditis and preserved LVEF with available follow-up data.

FIELD STRENGTH/SEQUENCE

Steady-state free precession cine and phase-sensitive inversion recovery segmented gradient echo late gadolinium enhancement sequences at 3.0 T.

ASSESSMENT

Left ventricular (LV) and LA strain were evaluated using feature tracking. LACI was calculated as the ratio of LA and LV volumes at LV end-diastole. Patients were followed-up with the primary endpoint being major adverse cardiovascular events (MACE).

STATISTICAL TESTS

Independent-samples t-test and Mann-Whitney U test to compare patients with and without MACE, receiver operating characteristic (ROC) curve analysis to define high/low risk groups, Kaplan-Meier survival analysis and Cox proportional hazards regression to assess prognosis. A P value of <0.05 was considered statistically significant.

RESULTS

The associations of LV strain parameters (including global radial, circumferential, and longitudinal strain) and LACI with MACE were not significant (P = 0.511, 0.108, 0.148, and 0.847, respectively). An optimal LA conduit strain (Ԑe) cutoff value of 10.4% was identified to best classify patients into low- and high-risk groups. Only Ԑe was significantly associated with MACE in both univariable (hazards ratio [HR] 0.936, 95% confidence interval [CI] 0.884-0.991) and multivariable Cox survival analyses (HR 0.937, 95% CI 0.884-0.994).

DATA CONCLUSION

LA conduit strain has prognostic value in patients with suspected myocarditis and preserved LVEF, incremental to conventional MRI outcome predictors, whereas LACI was not associated with MACE occurrence.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Unraveling Cardiovascular Risks and Benefits of COVID-19 Vaccines: A Systematic Review

The rapid development and deployment of mRNA and non-mRNA COVID-19 vaccines have played a pivotal role in mitigating the global pandemic. Despite their success in reducing severe disease outcomes, emerging concerns about cardiovascular complications have raised questions regarding their safety. This systematic review critically evaluates the evidence on the cardiovascular effects of COVID-19 vaccines, assessing both their protective and adverse impacts, while considering the challenges posed by the limited availability of randomized controlled trial (RCT) data on these rare adverse events. In adherence to PRISMA 2020 guidelines, we conducted a systematic review using the Scopus database, incorporating articles published from January 2020 to July 2024. Our search included terms related to COVID-19 vaccines and cardiovascular conditions. We selected relevant studies from case-control studies, cohort studies, and clinical trials, while excluding descriptive analyses, cross-sectional studies, and conference reports. Case reports were also included due to the limited availability of extensive RCT data on the rare cardiovascular adverse events associated with COVID-19 vaccines. Of the 6037 articles initially screened, 410 were assessed in detail and 175 studies were ultimately included. The review identified a variety of cardiovascular adverse effects associated with COVID-19 vaccines. mRNA vaccines were primarily linked to myocarditis and pericarditis, particularly in younger males, with lower cardiac risks compared to COVID-19 infection. Adenoviral vector vaccines were associated with thrombosis and thrombocytopenia. Inactivated vaccines had fewer severe cardiovascular reports but still presented risks. Takotsubo cardiomyopathy was most commonly observed following mRNA vaccination. Case reports provided valuable additional insights into these rare events, highlighting clinical presentations and potential risk factors not fully captured by larger epidemiological studies. This review reveals a nuanced cardiovascular risk profile for COVID-19 vaccines, with mRNA vaccines linked to rare myocarditis and pericarditis in young males and a higher incidence of Takotsubo cardiomyopathy in females. Adenoviral vaccines show a notable association with thrombosis. Despite these risks, the benefits of vaccination in preventing severe COVID-19 outcomes outweigh the potential complications, underscoring the importance of continued surveillance, case report documentation, and personalized risk assessment. The inclusion of case reports was critical, as they provided valuable real-world data that complemented the findings from large-scale studies and RCTs.

Cardiovascular magnetic resonance parametric mapping in the risk stratification of patients affected by chronic myocarditis

OBJECTIVES

Chronic myocardial inflammation is the substrate for arrhythmias and dilated cardiomyopathy onset, causing morbidity and mortality. Cardiovascular magnetic resonance (CMR) is the noninvasive gold standard for myocardial inflammation detection, due to the high sensitivity of the parametric mapping techniques. However, the potential prognostic capabilities of CMR mapping have not been studied in the setting of chronic myocarditis.

METHODS

This is a retrospective study on consecutive patients undergoing CMR with suspicion of chronic myocarditis from September 2017 to November 2021. CMR was acquired according to 2018 Lake Louise Criteria recommendations. The outcome (chronic heart failure, recurrent chronic myocarditic chest pain, ICD/PM implantation, arrhythmias [Lown class ≥ 2]) was collected at follow-up. The extent and degree of native T1, T2, and extracellular volume fraction alterations were used to create multivariate binary logistic regression models for outcome prediction, with or without left ventricle ejection fraction; their AUCs were compared with DeLong test. Differences between other parameters were assessed using Chi-square test, Fisher's exact test, or Mann-Whitney U-test.

RESULTS

The population included 88 patients (age 43 [32-52] yo), mostly male (53/88, 60%). After a median follow-up of 21 (17-34) months, 31/88 (35%) patients experienced the outcome. The model based on the extension of mapping alterations and LV dysfunction reached a good predictability (AUC 0.71). The model based on the intensity of mapping alterations and LV dysfunction had a very good performance (AUC 0.80).

CONCLUSION

The quantitative analysis of CMR mapping parameters indicative of myocardial damage severity may improve risk stratification in patients with chronic myocarditis.

CLINICAL RELEVANCE STATEMENT

The intensity of myocardial damage, assessed as the degree of native T1, T2, and ECV alteration, together with left ventricle dysfunction, improved patient risk stratification. Further prospective studies will be necessary for validation before clinical application.

KEY POINTS

Risk stratification of patients affected by chronic myocarditis is an unmet clinical need. Cardiovascular MRI (CMR) can role in risk stratification thanks to its multiparametric capabilities of tissue characterization. A model based on CMR parametric mapping and left ventricle ejection fraction can predict arrhythmia, heart failure, and recurrent symptoms.

Successful management of coagulation dysfunction in a patient with fulminant myocarditis: a case report

Fulminant myocarditis (FM) is an acute, diffuse inflammatory myocardial disease characterized by abrupt onset and extremely rapid progression. Patients typically exhibit haemodynamic abnormalities that may lead to respiratory failure, liver and renal failure, and subsequent coagulopathy. Collectively, these complications significantly increase the risk of early mortality. Currently, there is limited research on coagulation dysfunction associated with FM; therefore, achieving a rebalancing of the coagulation system is a challenge for successful treatment. We report a case of coagulation disorder secondary to FM, in which the patient recovered successfully and was discharged following comprehensive treatment and correction of coagulation function. By analyzing the etiology of this condition and emphasizing strategies for correcting coagulation disorders, we aim to provide valuable references for clinical diagnosis and management.

Global burden and attributable risk factors of inflammatory cardiomyopathy and myocarditis from 1990 to 2019

BACKGROUND

Our understanding of the global burden distribution of inflammatory cardiomyopathy and myocarditis is very limited.

OBJECTIVE

To comprehensively assess the global burden distribution and attributable risk factors of inflammatory cardiomyopathy and myocarditis from 1990 to 2019.

METHODS

We extracted the data on death, disability-adjusted life years (DALY), and age-standardized rate (ASR) of inflammatory cardiomyopathy and myocarditis from the 2019 Global Burden of Disease (GBD) study, including the comprehensive data and the data classified by age/sex. Evaluate the epidemic trend by calculating the estimated annual percentage change (EAPC) of the above variables. This paper discusses the spatial differences from four aspects: global, five socio-demographic index regions, 21 GBD regions, and 204 countries and regions. We also estimated the risk factors attributable to inflammatory cardiomyopathy and myocarditis-related deaths.

RESULTS

In 2019, the global death toll from inflammatory cardiomyopathy and myocarditis was 340,349, and the age-standardized mortality rate (ASDR) was 4.40/100,000, of which the elderly and men were the majority. Although ASR has decreased in developed areas, inflammatory cardiomyopathy and myocarditis are still important health problems in those relatively underdeveloped areas. Similar DALYs burden pattern of inflammatory cardiomyopathy and myocarditis was also observed during the study period. Globally, among men over 60 and women over 65, the proportion of deaths caused by high systolic blood pressure in 2019 was higher than that in 1990.

CONCLUSIONS

Inflammatory cardiomyopathy and myocarditis are still important global public health problems. The changing pattern of the burden of inflammatory cardiomyopathy and myocarditis varies with location, age, and sex, so it is essential to improve resource allocation to formulate more effective and targeted prevention strategies. In addition, the control of blood pressure should be emphasized.

Advancing Myocarditis Research: Evaluating Animal Models for Enhanced Pathophysiological Insights

PURPOSE OF REVIEW

This review aims to assess the current landscape of animal models used in myocarditis research, with a focus on understanding their utility in uncovering the pathophysiology of the disease. The goal is to evaluate these models' strengths and weaknesses and propose optimizations to make them more relevant and reliable for both mechanistic studies and therapeutic interventions in myocarditis.

RECENT FINDINGS

Recent studies have primarily utilized animal models, particularly viral and autoimmune myocarditis models, to study disease mechanisms. Coxsackievirus remains the most common virus used in viral myocarditis models, offering high success rates but limited applicability to human cases due to differences in infection patterns. Autoimmune myocarditis models, often involving humanized mice, have made strides in mimicking human immune responses but still face challenges in accuracy and clinical relevance. COVID-19 has introduced new avenues for research, especially concerning vaccine-induced myocarditis, although findings remain preliminary. Animal models remain crucial for myocarditis research, but each comes with distinct challenges. Viral models excel in success rate but suffer from partial relevance to human conditions. Autoimmune models are useful in immunological studies, though costly and less replicable. Vaccine-associated models are closely related to modern clinical conditions, but lack theoretical support and therefore lack reliability. Optimizing these models could improve our understanding of myocarditis and lead to more effective treatments. Future research should aim to refine these models to better simulate human conditions and enhance their clinical applicability, ultimately advancing the diagnosis and treatment of myocarditis.

COVID-19 Associated Myocarditis: Prevalence, Pathophysiology, Diagnosis, and Management

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a pandemic and affected public health greatly. While COVID-19 primarily damages the lungs, leading to cough, sore throat, pneumonia, or acute respiratory distress syndrome, it also infects other organs and tissues, including the cardiovascular system. In particular, myocarditis is a well-recognized severe complication of COVID-19 infection and could result in adverse outcomes. Angiotensin-Converting Enzyme2 is thought to play a pivotal role in SARS-CoV-2 infection, and immune overresponse causes overwhelming damage to the host's myocardium. Direct viral infection and injury do take a part as well, but more evidence is needed to strengthen this proposal. The clinical abnormalities include elevated cardiac biomarkers and electrocardiogram changes and impaired cardiac function that might be presented in echocardiography and cardiovascular magnetic resonance imaging. If necessary, the endomyocardial biopsy would give more forceful information to diagnosis and aid in treatment. Comparisons between COVID-19 myocarditis and other viral myocarditis are also discussed briefly.

Challenges in clinical translation of cardiac magnetic resonance imaging radiomics in non-ischemic cardiomyopathy: a narrative review

Background and Objective

Radiomics is an emerging technology that facilitates the quantitative analysis of multi-modal cardiac magnetic resonance imaging (MRI). This study aims to introduce a standardized workflow for applying radiomics to non-ischemic cardiomyopathies, enabling clinicians to comprehensively understand and implement this technology in clinical practice.

Methods

A computerized literature search (up to August 1, 2024) was conducted using PubMed to identify relevant studies on the roles and workflows of radiomics in non-ischemic cardiomyopathy. Expert discussions were also held to ensure the accuracy and relevance of the findings. Only English-language publications were reviewed.

Key Content and Findings

The paper details the essential processes of radiomics, including feature extraction, feature engineering, model construction, and data analysis. It emphasizes the role of MRI in assessing cardiac structure and function and demonstrates how MRI-based radiomics can aid in diagnosing and differentiating non-ischemic cardiomyopathies such as hypertrophic cardiomyopathy, dilated cardiomyopathy, and myocarditis. The study also investigates various cardiac MRI sequences to enhance the clinical application of radiomics.

Conclusions

The standardized radiomics workflow presented in this study aims to assist clinicians in effectively utilizing MRI-based radiomics for the diagnosis and management of non-ischemic cardiomyopathies, thereby improving clinical decision-making.

Global burden of myocarditis from 1990 to 2021: findings from the Global Burden of Disease Study 2021

BACKGROUND

Myocarditis is a major public health, social, and economic issue. Currently, few studies have provided comprehensive analyses of the global burden of myocarditis based on GBD (Global Burden Disease) 2021. We therefore analyzed long-term trends in the global burden of myocarditis from 1990 to 2021, described risk factors, examined the impact of COVID-19 (coronavirus infection disease 2019), and predicted future trends to inform health policy development and healthcare resource allocation.

METHOD

From the GBD 2021 database, incident cases, deaths, and DALYs (disability-adjusted life years) were obtained for countries, regions, ages, and sexes globally. The estimated annual percentage change (EAPC) was used to analyze Trends in age-standardized rates of myocarditis and significant time points were examined using joinpoint regression analysis.

RESULTS

Globally, the age-standardized incidence rate (ASIR), DALYs rate (ASDALYsR), and death rate (ASDR) for myocarditis in 2021 were 16.16 [(13.11 to 19.76) per 100 000 people], 12.41 [10.37 to 14.76) per 100 000 people], and 0.40 [0.32 to 0.47) per 100 000 people], respectively. High-income Asia Pacific had the highest myocarditis ASIR in 2021, whereas Central Europe had the highest ASDALYsR and ASDR. Gender comparison showed myocarditis was more common in men. The burden of myocarditis was larger in the elderly aged 80 and older, but children should not be neglected. Analysis revealed a rise in worldwide ASIR from 2016 to 2021 (APC = 0.0945, 95%CI: 0.0709 to 0.1440, p < 0.001). During COVID-19, myocarditis burden did not peak. Both high and low temperatures increase myocarditis risk. The Bayesian age-period-cohort (BAPC) model predicted that myocarditis ASIR would rise while ASDALYsR and ASDR would decrease.

CONCLUSIONS

The global burden of myocarditis remains a health issue that cannot be ignored and shows significant regional and sex-based differences. Effective and targeted strategies for the prevention and management of myocarditis in this population are needed to reduce the overall burden.

CLINICAL TRIAL NUMBER

Not applicable.

Global, regional, and national burden of myocarditis in children aged 0-14 years, 1990-2021: analysis for the global burden of disease study 2021

Objective

There are limited epidemiological data on myocarditis in children aged 0-14 years. This study aims to investigate the trends in incidence, mortality, disability-adjusted life years (DALYs), and corresponding estimated annual percentage change (EAPC) of myocarditis in children aged 0-14 years from 1990 to 2021.

Methods

We utilized the 2021 Global Burden of Disease, Injuries, and Risk Factors Study (GBD) analytical tools to examine the incidence, mortality, and DALYs of myocarditis in children aged 0-14 years, considering factors such as age, sex, region, sociodemographic index (SDI), and data from 204 countries or regions.

Results

In 2021, a total of 155.45/1000 people cases of myocarditis were reported globally in children. The cases of myocarditis in children increased from 143.80/1000 people (95% uncertainty interval [UI], 93.13-214.67) in 1990 to 155.45/1000 people (95% UI, 100.31-232.31) in 2021, increasing by 8.1% (95% UI, 6.04-9.73%). Over 30 years, the global incidence rate decreased from 8.27 (95% UI, 5.35-12.34) to 7.73 (95% UI, 4.99-11.55) per 100,000 population. The myocarditis-associated mortality rate decreased from 0.36 (95% UI, 0.25-0.51) to 0.13 (95% UI, 0.10-0.16) per 100,000 population. In 2021, the highest incidence of myocarditis in children occurred in High SDI regions. Regionally, High-income Asia Pacific had the greatest increase in incidence (EAPC, 0.25; 95% CI, 0.22-0.28). Japan had the highest incidence rate of myocarditis in children, while Haiti reported the highest myocarditis-associated mortality rate and DALYs rate. Globally, environmental/occupational risk, nonoptimal temperature, high temperature, and low temperature were key risk factors for myocarditis-associated mortality in children.

Conclusion

Between 1990 and 2021, myocarditis in children saw declining mortality and DALYs but rising incidence, especially in males. Children under 1 year face higher mortality and DALY rates despite lower incidence, stressing early diagnosis. High SDI regions report higher incidence but lower mortality, while low SDI areas need standardized treatment. Japan had the highest 2021 incidence, and China had the most deaths. Underscoring the urgency for enhanced medical resources, comprehensive research into the disease's etiology, and improved prevention strategies.

Management of acute myocarditis: a systematic review of clinical practice guidelines and recommendations

The management of acute myocarditis (AM) is addressed in multiple clinical guidelines. We systematically reviewed current guidelines developed by national and international medical organizations on the management of AM to aid clinical practice. Publications in MEDLINE, EMBASE and Cochrane were identified between 1 January 2013 and 12 April 2024. Additionally, the websites of relevant organizations and the Guidelines International Network, Guideline Central, and NHS knowledge and library hub were reviewed. Two reviewers independently screened titles and abstracts, two reviewers assessed the rigour of guideline development, and one reviewer extracted the recommendations. Two of the three guidelines identified showed good rigour of development. Those rigorously developed agreed on the definition of AM, sampling serum troponin as part of the workflow for AM, testing for B-type natriuretic peptides in heart failure, key diagnostic imaging in the form of cardiovascular magnetic resonance, coronary angiography to exclude significant coronary disease, indications for endomyocardial biopsy (EMB), and indications for immunosuppression and advanced treatment options. Discrepancies exist in sampling creatine kinase-myocardial bound as a marker of myocardial injury, indications for EMB, and indications for immunosuppression and treatment of uncomplicated AM. Evidence is lacking for the use of 18F-Fluorodeoxyglucose Positron Emission Tomography for myocardial imaging, exercise restriction, follow-up measures, and genetic testing, and there are few high-quality randomized trials to support treatment recommendations. Recommendations for management of AM in the guidelines have largely been developed from expert opinion rather than trial data.

Deep learning automatically distinguishes myocarditis patients from normal subjects based on MRI

Myocarditis, characterized by inflammation of the myocardial tissue, presents substantial risks to cardiovascular functionality, potentially precipitating critical outcomes including heart failure and arrhythmias. This investigation primarily aims to identify the optimal cardiovascular magnetic resonance imaging (CMRI) views for distinguishing between normal and myocarditis cases, using deep learning (DL) methodologies. Analyzing CMRI data from a cohort of 269 individuals, with 231 confirmed myocarditis cases and 38 as control participants, we implemented an innovative DL framework to facilitate the automated detection of myocarditis. Our approach was divided into single-frame and multi-frame analyses to evaluate different views and types of acquisitions for optimal diagnostic accuracy. The results demonstrated a weighted accuracy of 96.9%, with the highest accuracy achieved using the late gadolinium enhancement (LGE) 2-chamber view, underscoring the potential of DL in distinguishing myocarditis from normal cases on CMRI data.

Emerging Biomarkers in Cardiac Sarcoidosis and Other Inflammatory Cardiomyopathies

PURPOSE OF REVIEW

Cardiac sarcoidosis and other inflammatory cardiomyopathies are disorders causing cardiac inflammation and leading to heart failure, arrythmias and cardiac arrest. Diagnosis of these entities remains challenging and multimodal. Thus, there is a growing need to develop reliable biomarkers that can aid in the diagnosis. This review aims to summarize and highlight recent findings in the field of biomarkers for cardiac sarcoidosis and inflammatory cardiomyopathy.

RECENT FINDINGS

Multiple categories of biomarkers including novel molecules are being investigated with the latest evidence showing promising results. Some of these biomarkers are proven to be useful as diagnostic and prognostic aids in cardiac sarcoid and inflammatory cardiomyopathy. The identification of cost-effective and accurate biomarkers is useful not only for enhancing diagnostic accuracy but also for informing therapeutic decision-making processes. This advancement would facilitate the timely institution of immunosuppressive therapies, ultimately leading to improved patient outcomes.

Rotavirus-Associated Myocarditis in an Immunocompetent Adult: A Case Report

A previously healthy, 28-year-old man presented with a two-day history of diarrhea and chest pain, suggestive of infectious myocarditis. Initial workup revealed elevated troponin-I levels and diffuse ST-segment elevations on electrocardiogram (ECG). Transthoracic echocardiography showed a reduced left ventricular ejection fraction (40-45%), posteroinferior wall akinesis, and a small pericardial effusion. Stool studies were positive for rotavirus antigen via enzyme immunoassay (EIA). Cardiac magnetic resonance imaging (MRI) and endomyocardial biopsy (EMB) were not performed due to facility limitations; however, clinical findings, troponin-I trends, and echocardiographic abnormalities supported the diagnosis of rotavirus-associated myocarditis. The patient was treated with oral rehydration, colchicine, and metoprolol, leading to symptom resolution and a decline in troponin-I levels. This case underscores the importance of considering rotavirus as a potential etiologic agent in myocarditis, even in immunocompetent adults without significant comorbidities, and highlights the need for clinicians to recognize gastrointestinal viruses as possible causes of cardiac inflammation.

Changing Epidemiology of Myocarditis in Australia: A Population-Based Cohort Study

Background: Myocarditis is a serious disease that has drawn increasing attention due to its association with COVID-19 and vaccination. This study investigates the epidemiology of myocarditis beyond the COVID-19 pandemic, including its incidence and outcomes over time. Methods: We analyzed the population-wide retrospective data from the Admitted-Patient-Data-Collection database of patients admitted to hospitals in New South Wales (NSW), Australia, with a diagnosis of myocarditis from 2001 to 2022. The incidence of myocarditis, changing classification of myocarditis over time, and complications of myocarditis over time were all calculated. Results: There were 4071 patients diagnosed with their first episode of myocarditis, with a median age of 42 years old, and 66% were male. The incidence of myocarditis in NSW has tripled over 20-years to 8.3 per-100,000-persons by 2022. Reactive myocarditis (i.e., myocarditis within 30-days of a respiratory or digestive illness) accounted for 38% of first presentations of myocarditis. Post COVID-19 myocarditis, a subset of reactive myocarditis, accounted for 42% of myocarditis admissions since the onset of the COVID-19 pandemic in Australia. Eight percent of patients had a background history of malignancy, and 6% had a history of autoimmune disease. In-hospital mortality was 4.5% during the entire study period but has been falling by 11% per year. During follow up, most readmissions for myocarditis occurred within 6-months; with 5.1% recurrence at 6-months compared to only 6.7% at 5-years. Conclusions: Myocarditis is an important condition with increasing incidence in Australia and with markedly changing characteristics in the pandemic and post pandemic era.

Puerarin inhibits macrophage M1 polarization by combining STAT1 to reduce myocardial damage in EAM model mice

Myocarditis is an inflammatory lesion of the myocardium that is caused by a variety of factors. At present, treatment of symptoms remains the main clinical intervention, but it cannot reduce the myocarditis damage caused by inflammation. M1 macrophages are thought to contribute significantly to the occurrence and development of inflammation by secreting a large number of proinflammatory factors. Puerarin is an isoflavone derivative isolated from pueraria that can be used as a dietary supplement and exerts wide range of anti-inflammatory and antioxidant effects. However, the mechanism underlying its anti-inflammatory effects needs to be further studied. The objective of this study was to investigate whether puerarin inhibited M1 polarization by affecting the JAK-STAT signaling pathway in a mouse model of autoimmune myocarditis, thus inhibiting the occurrence of inflammation in experimental autoimmune myocarditis (EAM) model mice. The results showed that EAM model mice treated with puerarin showed milder clinical symptoms and inflammatory infiltration than EAM model mice. Puerarin suppressed the in vivo and in vitro JAK1/2-STAT1 signal transduction in macrophages, thus inhibiting M1 polarization, reducing the secretion of proinflammatory factors, and ultimately decreasing IFN-γ and TNF-α levels in vivo, which led to myocardial apoptosis. Thus, puerarin could alleviate myocardial damage caused by inflammation. The conclusion of this study was that puerarin reduced myocardial damage in EAM model mice by regulating the polarization of macrophages toward M1, and this inhibitory effect may be achieved by inhibiting JAK1/2-STAT1 signaling.

Viral myocarditis: From molecular mechanisms to therapeutic prospects

Myocarditis is characterized as local or diffuse inflammatory lesions in the myocardium, primarily caused by viruses and other infections. It is a common cause of sudden cardiac death and dilated cardiomyopathy. In recent years, the global prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the widespread vaccination have coincided with a notable increase in the number of reported cases of myocarditis. In light of the potential threat that myocarditis poses to global public health, numerous studies have sought to elucidate the pathogenesis of this condition. However, despite these efforts, effective treatment strategies remain elusive. To collate the current research advances in myocarditis, and thereby provide possible directions for further research, this review summarizes the mechanisms involved in viral invasion of the organism and primarily focuses on how viruses trigger excessive inflammatory responses and in result in different types of cell death. Furthermore, this article outlines existing therapeutic approaches and potential therapeutic targets for the acute phase of myocarditis. In particular, immunomodulatory treatments are emphasized and suggested as the most extensively studied and clinically promising therapeutic options.

Exploring the therapeutic mechanisms of heart failure with Chinese herbal medicine: a focus on miRNA-mediated regulation

Heart failure (HF) is a clinical condition caused by abnormalities in the heart's structure or function, primarily manifested as diminished ability of the heart to pump blood, which leads to compensatory activation of neurohormones and increased left ventricular filling pressure. HF is one of the fastest-growing cardiovascular diseases globally in terms of incidence and mortality, negatively impacting patients' quality of life and imposing significant medical and economic burdens. Despite advancements in the treatment of HF, hospitalization and mortality remain rates high. In China, Chinese herbal medicine (CHM) has historically played a prominent role in addressing HF, with significant proven efficacy. MicroRNA (miRNA) exerts a pivotal regulatory influence on the maintenance of regular cardiac activity and the progression of HF. MiRNAs, a category of single-stranded RNA molecules, are characterized by their inability to code for proteins. They regulate gene expression by binding to the 3'-untranslated region (3'-UTR) of target mRNAs, thereby influencing the onset and progression of various diseases. Abnormal expression of specific miRNAs is closely associated with HF pathological processes, such as cardiomyocyte apoptosis, myocardial fibrosis, and cardiac hypertrophy. This abnormal expression can influence the pathological progression of HF through the regulation of miRNA expression. This article reviews the regulatory role of miRNAs in HF pathology discusses how CHM compounds and their active ingredients can ameliorate HF pathology through the regulation of miRNA expression. In conclusion, miRNAs represent promising therapeutic targets for HF, and CHM provides a novel strategy for treatment through the regulation of miRNA expression. Future studies must delve deeper into the precise mechanisms by which CHM modulates miRNAs and fully explore its potential for clinical application in HF treatment.

Association between human blood metabolome and risk of myocarditis: a mendelian randomization study

Myocarditis is a common disease of the cardiovascular and immune systems, but the relationship between relevant blood metabolites and the risk of myocarditis has not been well-established. To identify potential biometabolic markers associated with myocarditis, we conducted a two-sample Mendelian randomization (MR) study. We performed preliminary MR analysis using the inverse variance weighted (IVW) method, supplemented by MR-Egger, weighted median, and weighted mode methods to adjust for false discovery rate (FDR). Confounders were screened using the GWAS Catalog website. Sensitivity analyses included Cochrane Q-test, Egger regression, Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO), scatterplots, funnel plots, and forest plots. For genetic and directional analysis, we employed co-localization analysis and the Steiger test. MR analysis was performed using the FinnGen database and meta-analysis was performed using the IEU database. MR analysis identified significant correlations for five metabolic biomarkers after FDR correction. These included four known metabolites: kynurenine, 1-stearoyl-GPE (18:0), deoxycarnitine, and 5-acetylamino-6-formylamino-3-methyluracil, as well as one unknown metabolite, X-25,422. Among these, kynurenine (OR = 1.441, 95%CI = 1.089-1.906, p-value = 0.018) and 1-stearoyl-GPE (18:0) (OR = 1.263, 95%CI = 1.029-1.550, p-value = 0.029) were identified as risk factors for myocarditis, while deoxycarnitine (OR = 0.813, 95%CI = 0.676-0.979, p-value = 0.029), 5-acetylamino-6-formylamino-3-methyluracil (OR = 0.864, 95% CI = 0.775-0.962, p-value = 0.018), and X-25,422 (OR = 0.721, 95%CI = 0.587-0.886, p-value = 0.009) were found to be protective factors. No evidence of heterogeneity, horizontal pleiotropy, or sensitivity issues was observed, and no shared genetic factors between exposure and outcome were detected. The causality was in the correct direction. Meta-analysis further confirmed the causal relationship between the five metabolites and myocarditis. This study identifies a causal relationship between five circulating metabolites and myocarditis. Kynurenine, 1-stearoyl-GPE (18:0), deoxycarnitine, X-25,422, and 5-acetylamino-6-formylamino-3-methyluracil may serve as potential drug targets for myocarditis, providing a theoretical basis for the prevention, diagnosis, and treatment of the condition.

High Mobility Group Box 1 and Cardiovascular Diseases: Study of Act and Connect

Cardiovascular disease is the deadly disease that can result in sudden death, and inflammation plays an important role in its onset and progression. High mobility group box 1 (HMGB1) is a nuclear protein that regulates transcription, DNA replication, repair, and nucleosome assembly. HMGB1 is released passively by necrotic tissues and actively secreted by stressed cells. Extracellular HMGB1 functions as a damage associated molecular patterns molecule, producing numerous redox forms that induce a range of cellular responses by binding to distinct receptors and interactors, including tissue inflammation and regeneration. Extracellular HMGB1 inhibition reduces inflammation and is protective in experimental models of myocardial ischemia/reperfusion damage, myocarditis, cardiomyopathies caused by mechanical stress, diabetes, bacterial infection, or chemotherapeutic drugs. HMGB1 administration following a myocardial infarction followed by permanent coronary artery ligation improves cardiac function by stimulating tissue regeneration. HMGB1 inhibits contractility and produces hypertrophy and death in cardiomyocytes, while also stimulating cardiac fibroblast activity and promoting cardiac stem cell proliferation and differentiation. Maintaining normal nuclear HMGB1 levels, interestingly, protects cardiomyocytes from apoptosis by limiting DNA oxidative stress, and mice with HMGB1cardiomyocyte-specific overexpression are partially protected from cardiac injury. Finally, elevated levels of circulating HMGB1 have been linked to human heart disease. As a result, following cardiac damage, HMGB1 elicits both detrimental and helpful responses, which may be due to the formation and stability of the various redox forms, the particular activities of which in this context are mostly unknown. This review covers recent findings in HMGB1 biology and cardiac dysfunction.

Fulminant myocarditis associated with human rhinovirus A66 infection: a case report

Background

Human rhinoviruses (HRVs) are among the most common pathogens of upper respiratory infections, and they are responsible for the common cold. An increasing number of studies have shown that HRV is associated with more severe illness. However, HRV-associated fulminant myocarditis has rarely been reported.

Patient presentation

A previously healthy 8-year-old boy developed fever, fatigue, and vomiting for 3 days, with a subsequent exacerbation accompanied by confusion lasting for 9 h. The day before admission, the patient presented with oliguria, confusion, and hypotension, and he was suspected of having myocarditis. The patient was transferred to our hospital for further diagnosis and treatment. On admission, rough and moist rales were detected, and the heart sounds were muffled, accompanied by an irregular heart rhythm and a gallop. An electrocardiogram (EKG) revealed a wide QRS complex, ST-segment depression, premature ventricular contractions, and complete right bundle branch block. Laboratory tests revealed that brain natriuretic peptide (BNP), N-terminal pro BNP (NT-pro BNP), and cardiac biomarkers, such as troponin I, creatinine kinase (CK), and creatinine kinase-MB (CK-MB) were elevated. Additionally, echocardiography revealed an ejection fraction of approximately 28%. The child developed severe cardiac dysfunction and tissue hypoperfusion, and the cardiogenic shock could not be corrected despite active drug therapy. He had indications for ECMO implantation. A rarely reported rhinovirus, namely, A66, was detected in his bronchoalveolar lavage fluid and oropharyngeal swabs via metagenomic next-generation sequencing and a PCR assay. Bacterial culture of all the samples yielded negative results.

Conclusions

This case presents a patient with severe human rhinovirus A66 infection, which is likely responsible for fulminant myocarditis. This report facilitates prompt diagnosis and treatment of fulminant myocarditis. Clinicians should consider rhinovirus as a possible pathogen of fulminant myocarditis, especially when patients present with symptoms or signs of heart involvement.

Prognostic Implications of Clinical and Imaging Diagnostic Criteria for Myocarditis

BACKGROUND

The European Society of Cardiology (ESC), the American College of Cardiology, the American Heart Association, and expert consensus documents provide different diagnostic criteria for myocarditis. Their overlap and prognostic value have never been compared.

OBJECTIVES

This study aims to assess and compare the predictive value of ESC criteria for clinically suspected myocarditis, updated Lake-Louise criteria (LLC), American Heart Association criteria for probable acute myocarditis (pAM), and expert consensus criteria for acute myocarditis (AM) and complicated myocarditis (CM).

METHODS

Patients with a clinical suspicion of myocarditis referred for cardiac magnetic resonance were enrolled at 2 centers. Those with any prior cardiomyopathy were excluded. The association of composite outcome events (heart failure hospitalization, recurrent myocarditis, sustained ventricular tachycardia, or death) with ESC diagnostic criteria, LLC, pAM, AM, and CM were compared.

RESULTS

Among 1,557 consecutive patients referred for cardiac magnetic resonance with possible myocarditis, 1,050 (62.6% male; 48.9 ± 16.8 years of age) were without an alternative diagnosis. Of those, 938 (89.3%) met ESC criteria for clinically suspected myocarditis, 299 (28.5%) LLC, and 356 (33.9%), 216 (20.6%), and 77 (7.3%) pAM, AM, and CM, respectively. Adverse events occurred in 161 patients (15.3%) during a median follow-up of 3.4 years. The highest annualized event rates (6.6%) were observed in patients meeting LLC, whereas negative ESC criteria indicated excellent prognosis (0.7% annualized event rate). Among all myocarditis definitions, ESC criteria and LLC were the strongest multivariable outcome predictors and had independent and incremental prognostic value (HRadjusted: 3.87; 95% CI: 1.22-12.2; P = 0.021, and HRadjusted: 2.53; 95% CI: 1.83-3.49; P < 0.001, respectively) when adjusted for clinical characteristics.

CONCLUSIONS

In a real-world cohort of patients with possible myocarditis, diagnosis was reached in most patients using ESC criteria whereas only approximately one-quarter of patients reached a diagnosis with LLC. The independent prognostic value of ESC-criteria and LLC highlights the complementary role of clinical and CMR-based findings in the diagnosis and risk stratification of myocarditis.

Multiparametric Cardiac Magnetic Resonance Imaging to Discriminate Endomyocardial Biopsy-Proven Chronic Myocarditis From Healed Myocarditis

BACKGROUND

Detecting ongoing inflammation in myocarditis patients has prognostic relevance, but there are limited data on the detection of chronic myocarditis and its differentiation from healed myocarditis.

OBJECTIVES

This study sought to assess the performance of cardiac magnetic resonance (CMR) for the detection of ongoing inflammation and the discrimination of chronic myocarditis from healed myocarditis.

METHODS

Consecutive patients with persistent symptoms (>30 days) suggestive of myocarditis were prospectively enrolled from a single tertiary center. All patients underwent a multiparametric 1.5-T CMR protocol including biventricular strain, T1/T2 mapping, and late gadolinium enhancement (LGE). Endomyocardial biopsy was chosen for the reference standard diagnosis.

RESULTS

Among 452 consecutive patients, 103 (median age: 50 years; 66 men) had evaluable CMR and cardiopathologic reference diagnosis: 53 (51%) with chronic lymphocytic myocarditis and 50 (49%) with healed myocarditis. T2 mapping as a single parameter showed the best accuracy in detecting chronic myocarditis, if abnormal in ≥3 segments (92%; 95% CI: 85-97), and provided the best discrimination from healed myocarditis, as defined by the area under the receiver-operating characteristic curve (0.87 [95% CI: 0.79-0.93]; P < 0.001), followed by radial peak systolic strain rate of the left ventricle (0.86) and the right ventricle (0.84); T1 mapping (0.64), extracellular volume fraction (0.62), and LGE (0.57). Specificity increased when T2 mapping was combined with elevation of either troponin or C-reactive protein.

CONCLUSIONS

A multiparametric CMR protocol allows detection of ongoing myocardial inflammation and discrimination of chronic myocarditis from healed myocarditis, with segmental T2 mapping and biventricular strain analysis showing higher diagnostic accuracy compared with T1 mapping, extracellular volume fraction, and LGE. The use of biomarkers (troponin or C-reactive protein) may improve specificity.

Pancreatitis-associated Myocarditis: Systematic Review and Meta-analysis of a Deadly Duo

Myocardial injury is a recognized complication of acute pancreatitis, whereas myocarditis has only been occasionally reported and has not been systematically evaluated. We systematically reviewed PubMed literature published up to January 2024 for studies including both "myocarditis" and "pancreatitis" as keywords. Relevant data regarding patient characteristics and outcomes were collected and analyzed. A total of 31 patients from 31 independent studies were included. The etiology of pancreatitis was viral in 52%, bacterial in 20%, toxic in 16%, autoimmune in 9%, and idiopathic in 3%. 23% of patients were immunocompromised. Median high sensitivity-cardiac troponin T was 342 (IQR 73-890) ng/L and N-terminus-pro-brain natriuretic peptide was 11053 (IQR 1397-26150) pg/mL. The average left ventricular ejection fraction was 33±13%. Fulminant myocarditis, presenting with cardiogenic shock and/or malignant ventricular arrhythmias occurred in 48% of patients, more frequently in men than in women (P=0.026). Severe myocarditis occurred in 42% of edematous and 60% of necrotizing pancreatitis (P=0.56). No association was found between the severity of myocarditis and plasma levels of amylase (P=0.98) and lipase (P=0.83). The relative frequency of severe myocarditis was 80% in pancreatitis due to Leptospirosis, and 40% in pancreatitis due to viral infections. The mortality rate was 22%: 13% died during hospitalization and 9% after. Myocarditis is a potentially lethal complication of pancreatitis and is more frequently associated with viral etiology in immunocompromised individuals. Based on such findings, cardiac troponin measurements and an electrocardiogram are advisable to exclude myocardial involvement in selected patients. Confirmatory diagnosis and prognostic assessments should be based on cardiac magnetic resonance imaging.

Acute myocarditis in a paediatric patient with pre-existing dilated cardiomyopathy following SARS-COV-2 infection: a journey from decompensation to heart transplantation

A 10-year-old child with stabilised idiopathic dilated cardiomyopathy was admitted to the hospital with sudden worsening of heart failure. Further analysis showed increased NT-proBNP and positive for COVID-19. Myocarditis secondary to COVID-19 was assumed. Recurrent hospitalizations with inotropic support were required due to the progressive worsening of cardiac function. Seven months after SARS-CoV-2 myocarditis, she underwent heart transplantation.

Regulatory T Cells in Pathological Cardiac Hypertrophy: Mechanisms and Therapeutic Potential

BACKGROUND

Pathological cardiac hypertrophy is linked to immune-inflammatory injury, and regulatory T cells (Tregs) play a crucial role in suppressing immune-inflammatory responses. However, the precise role of Tregs in pathological cardiac hypertrophy remains unclear.

OBJECTIVE

To summarize the current knowledge on the role and mechanisms of Tregs in pathological cardiac hypertrophy and explore their perspectives and challenges as a new therapeutic approach.

RESULTS

Treg cells may play an important protective role in pressure overload (hypertension, aortic stenosis), myocardial infarction, metabolic disorders (diabetes, obesity), acute myocarditis, cardiomyopathy (hypertrophic cardiomyopathy, storage diseases), and chronic obstructive pulmonary disease-related pathological cardiac hypertrophy. Although some challenges remain, the safety and efficacy of Treg-based therapies have been confirmed in some clinical trials, and engineered antigen-specific Treg cells may have better clinical application prospects due to stronger immunosuppressive function and stability.

CONCLUSION

Targeting the immune-inflammatory response via Treg-based therapies might provide a promising and novel future approach to the prevention and treatment of pathological cardiac hypertrophy.

Novel Treatment for Pre-XDR Tuberculosis Linked to a Lethal Case of Acute Myocarditis

The management of resistant tuberculosis (tb) can be extremely difficult, especially in case of novel unpredicted complications. In this report, we present a case of a 48-year-old patient with pre-extensively drug-resistant (XDR) tb who received a treatment regimen including pretomanid, bedaquiline, linezolid, cycloserine, and amikacin and died due to myocarditis. Acquired resistance to first- and second-line drugs developed due to previous poor adherence to medication. The clinical presentation of the patient, along with her initial ultrasonographical, electrocardiogram (ECG), and laboratory examinations, were typical for acute myocarditis; however, the patient was considered unstable, and further investigations, including magnetic resonance imaging (MRI), pericardiocentesis, and endomyocardial biopsy were not performed. To our knowledge, this is the first case of myocarditis in such a patient, the clinical features of which raised a high suspicion of drug induction that could be attributed to the treatment regimen that was administered. Clinicians who manage cases of drug-resistant tb should be aware of this newly reported, potentially lethal, adverse event.

Coxsackievirus group B3 regulates ASS1-mediated metabolic reprogramming and promotes macrophage inflammatory polarization in viral myocarditis

Coxsackievirus group B3 (CVB3) belongs to the genus Enteroviruses of the family Picornaviridae and is the main pathogen underlying viral myocarditis (VMC). No specific therapeutic is available for this condition. Argininosuccinate synthase 1 (ASS1) is a key enzyme in the urea cycle that converts citrulline and aspartic acid to argininosuccinate. Here, we found that CVB3 and its capsid protein VP2 inhibit the autophagic degradation of ASS1 and that CVB3 consumes citrulline to upregulate ASS1, triggers urea cycle metabolic reprogramming, and then activates macrophages to develop pro-inflammatory polarization, thereby promoting the occurrence and development of VMC. Conversely, citrulline supplementation to prevent depletion can downregulate ASS1, rescue macrophage polarization, and alleviate the pathogenicity of VMC. These findings provide a new perspective on the occurrence and development of VMC, revealing ASS1 as a potential new target for treating this disease.

IMPORTANCE

Viral myocarditis (VMC) is a common and potentially life-threatening myocardial inflammatory disease, most commonly caused by CVB3 infection. So far, the pathogenesis of VMC caused by CVB3 is mainly focused on two aspects: one is the direct myocardial injury caused by a large number of viral replication in the early stage of infection, and the other is the local immune cell infiltration and inflammatory damage of the myocardium in the adaptive immune response stage. There are few studies on the early innate immunity of CVB3 infection in myocardial tissue, but the appearance of macrophages in the early stage of CVB3 infection suggests that they can play a regulatory role as early innate immune response cells in myocardial tissue. Here, we discovered a possible new mechanism of VMC caused by CVB3, revealed new drug targets for anti-CVB3, and discovered the therapeutic potential of citrulline for VMC.

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.

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.