Acute myocarditis. Rapid diagnosis by PCR in children

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

BACKGROUND

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

MAIN BODY

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

CONCLUSIONS

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

Persistent viral infections and their role in heart disease

Viral infections are the culprit of many diseases, including inflammation of the heart muscle, known as myocarditis. Acute myocarditis cases have been described in scientific literature, and viruses, such as parvovirus B19, coxsackievirus B3, or more recently, SARS-CoV-2, were the direct cause of cardiac inflammation. If not treated, myocarditis could progress to dilated cardiomyopathy, which permanently impairs the heart and limits a person's lifespan. Accumulated evidence suggests that certain viruses may persist in cardiac tissue after the initial infection, which could open up the door to reactivation under favorable conditions. Whether this chronic infection contributes to, or initiates, cardiac damage over time, remains a pressing issue in the field of virus-induced heart pathology, and it is directly tied to patients' treatment. Previously, large case studies found that a few viruses: parvovirus B19, coxsackievirus, adenovirus, human herpesvirus 6, cytomegalovirus and Epstein-Barr virus, are most commonly found in human endomyocardial biopsy samples derived from patients experiencing cardiac inflammation, or dilated cardiomyopathy. SARS-CoV-2 infection has also been shown to have cardiovascular consequences. This review examines the role of viral persistence in cardiac inflammation and heart disease, and discusses its implications for patients' outcomes.

Pediatric Myocarditis: What Have We Learnt So Far?

Myocarditis is an inflammatory disease of the myocardium that is troublesome to diagnose and manage, especially in children. Since the introduction of endomyocardial biopsy (EMB), new diagnostic tools have provided useful data. Especially when enhanced with immunohistochemistry and polymerase chain reaction (PCR) studies, EMB remains the gold standard for the diagnosis. Notably, cardiac magnetic resonance (MRI) is a non-invasive tool that can confirm the diagnosis and has a particular usefulness during the follow-up. The causes of myocarditis are heterogeneous (mostly viral in children). The course and outcome of the illness in the pediatric population represent a complex interaction between etiologic agents and the immune system, which is still not fully understood. The clinical presentation and course of myocarditis vary widely from paucisymptomatic illness to acute heart failure refractory to therapy, arrhythmias, angina-like presentation and sudden cardiac death. In this setting, cardiac biomarkers (i.e., troponins and BNP), although unspecific, can be used to support the diagnosis. Finally, the efficacy of therapeutic strategies is controversial and not confirmed by clinical trials. In this review, we summarized the milestones in diagnosis and provided an overview of the therapeutic options for myocarditis in children.

Endomyocardial Biopsy in Pediatric Myocarditis and Dilated Cardiomyopathy: A Tool in Search for a Role

Endomyocardial biopsy (EMB) is a well-known diagnostic tool for the investigation and treatment of myocardial diseases and remains the gold standard for the diagnosis of myocarditis. Due to its invasiveness, with a complication rate ranging from 1 to 15%, its role in the diagnostic work-up of pediatric heart failure is not well established. The aim of this review is to define the role of EMB as diagnostic technique in the work up of children presenting with severe left ventricular dysfunction with the support of our center experience.

MicroRNA-324-3p Plays A Protective Role Against Coxsackievirus B3-Induced Viral Myocarditis

Viral myocarditis (VM) is an inflammatory disease of the myocardium associated with heart failure, which is caused by common viral infections. A majority of the infections are initiated by coxsackievirus B3 (CVB3). MicroRNAs (miRNAs) have a major role in various biological processes, including gene expression, cell growth, proliferation, and apoptosis, as well as viral infection and antiviral immune responses. Although, miRNAs have been found to regulate viral infections, their role in CVB3 infection remains poorly understood. In the previous study, miRNA microarray results showed that miR-324-3p expression levels were significantly increased when cells and mice were infected with CVB3. It was also found that miR-324-3p downregulated TRIM27 and decreased CVB3 replication in vitro and in vivo. In vitro, analysis of downstream signaling of TRIM27 revealed that, miR-324-3p inhibited CVB3 infection, and reduced cytopathic effect and viral plaque formation by reducing the expression of TRIM27. In vivo, miR-324-3p decreased the expression of TRIM27, reduced cardiac viral replication and load, thereby strongly attenuating cardiac injury and inflammation. Taken together, this study suggests that miR-324-3p targets TRIM27 to inhibit CVB3 replication and viral load, thereby reducing the cardiac injury associated with VM.

Diagnosis and immunosuppressive treatment of inflammatory cardiomyopathy: a case report

Objectives: Definite diagnosis of myocarditis requires an endomyocardial biopsy (EMB) showing an inflammatory infiltrate. However, there are important limitations on establishing the diagnosis solely upon histological criteria. The main objective of this case report is to highlight the difficulty of diagnosis, but also to evaluate treatment in virus-negative inflammatory cardiomyopathy.Case report: We present the case of a 53-year-old man with an inflammatory cardiomyopathy based on cardiac magnetic resonance (CMR) findings consistent with extensive myocardial inflammation and a significantly depressed left ventricular ejection fraction (LVEF). Treatment with immunosuppressive therapy resulted in improvement of cardiac function and performance status, while also eliminating the need for ICD implantation.Conclusion: Cardiac magnetic resonance (CMR) has a high diagnostic accuracy and has become the primary diagnostic tool for noninvasive assessment of suspected myocarditis. EMBs should be analyzed using immunohistochemistry and viral polymerase chain reaction to increase the diagnostic sensitivity of histology. Immunosuppressive therapy should be considered in virus-negative inflammatory cardiomyopathy.

Epidemiological Impact of Myocarditis

Myocarditis is an inflammatory disease of the heart muscle with a wide range of potential etiological factors and consequently varying clinical patterns across the world. In this review, we address the epidemiology of myocarditis. Myocarditis was considered a rare disease until intensified research efforts in recent decades revealed its true epidemiological importance. While it remains a challenge to determine the true prevalence of myocarditis, studies are underway to obtain better approximations of the proportions of this disease. Nowadays, the prevalence of myocarditis has been reported from 10.2 to 105.6 per 100,000 worldwide, and its annual occurrence is estimated at about 1.8 million cases. This wide range of reported cases reflects the uncertainty surrounding the true prevalence and a potential underdiagnosis of this disease. Since myocarditis continues to be a significant public health issue, particularly in young adults in whom myocarditis is among the most common causes of sudden cardiac death, improved diagnostic and therapeutic procedures are necessary. This manuscript aims to summarize the current knowledge on the epidemiology of myocarditis, new diagnostic approaches and the current epidemiological impact of the COVID-19 pandemic.

Diagnosis, Evaluation, and Treatment of Myocarditis in Children

Myocarditis in the pediatric population can be a challenging diagnosis to make and often requires utilization of multiple diagnostic modalities. The cause is often due to a viral infection with activation of the innate and acquired immune response with either recovery or disease progression. Laboratory testing often includes inflammatory markers, cardiac troponin levels, and natriuretic peptides. Noninvasive testing should include electrocardiogram, echocardiogram, and possibly an MRI. Treatment of myocarditis remains controversial with most providers using immune modulators with intravenous immunoglobulin and corticosteroids.

Inflammatory dilated cardiomyopathy : Etiology and clinical management

Inflammatory dilated cardiomyopathy (DCMi) is a syndrome, not an etiological disease entity. The infective etiology and the immunopathology can be best determined through endomyocardial biopsy with a complete work-up by light microscopy, immunohistology, and polymerase chain reaction for microbial agents. This review focuses on the methodological advances in diagnosis in the past few years and exemplifies the importance of an etiology-orientated treatment in different case scenarios. In fulminant nonviral myocarditis, immunosuppressive treatment together with hemodynamic stabilization of the patient via mechanical circulatory support (e.g., microaxial pumps, extracorporeal membrane oxygenation, left ventricular assist device) can be life-saving. For viral inflammatory cardiomyopathy, intravenous immunoglobulin treatment can resolve inflammation and often eradicate the virus.

Story telling of myocarditis

Myocarditis was discovered as heart disease at autopsy with the use of microscope. In 1900, with the name of acute interstitial myocarditis, Carl Ludwig Alfred Fiedler first reported the history of a sudden cardiac heart failure, in the absence of coronary, valve, pericardial disease or classical specific infections with multiorgan involvement. He postulated a peculiar isolated acute inflammation of the myocardium with poor prognosis due to invisible microorganisms, which years later would have been identified as viruses. Subsequent revision of Fiedler original histologic slides by Schmorl showed cases with either lymphocytic or giant cell infiltrates. The in vivo diagnosis became possible with the right heart catheterism and endomyocardial biopsy. Employment of immunohistochemistry and molecular techniques improved the diagnosis and etiology identification. The mechanism of myocyte injury by coxsackie virus was identified in protease 2A coded by the virus and disrupting the dystrophin in the cytoskeleton. Both RNA and DNA viruses may be cardiotropic, and coxsackie and adenovirus share a common receptor (CAR). Unfortunately, vaccination is not yet available. Cardiac Magnetic Resonance is a revolutionary diagnostic tool by detecting edema, of myocardial inflammation. However endomyocardial biopsy remains the gold standard for etiological and histotype diagnosis, with limited sensitivity due to sampling error. Viral lymphocytic fulminant myocarditis may not be fatal and the employment of mechanical assistant device - ECMO in acute phase for temporary support may be lifesaving with good prognosis.

A case report of myocarditis combined with hepatitis caused by herpes simplex virus

BACKGROUND

Viral myocarditis presents with various symptoms, including fatal arrhythmia and cardiogenic shock, and may develop into chronic myocarditis and dilated cardiomyopathy in some patients. We report a case of viral myocarditis and hepatitis caused by herpes simplex virus.

CASE PRESENTATION

A 20-year-old woman was admitted to our hospital with fever, fatigue, and anorexia. The initial investigation showed elevated liver enzyme levels and elevated creatine phosphokinase, and computed tomography showed diffuse swelling and internal heterogeneous image in the liver. These findings were consistent with acute hepatitis; therefore, we performed a liver biopsy, which showed parenchymal necrosis and lymphocytic infiltration. The night that the liver biopsy was performed, blood pressure gradually decreased and revealed cardiogenic shock. Electrocardiography showed diffuse ST-segment elevation, and echocardiography showed a dilated, spherical ventricle with reduced systolic function and pericardial effusion. An endomyocardial biopsy revealed lymphocyte infiltration of the myocardium, confirming acute myocarditis. After a few days, tests for immunoglobin M and immunoglobin G antibodies against herpes simplex virus were positive.

CONCLUSIONS

We presented a rare case of myocarditis combined with hepatitis that was caused by herpes simplex virus. Acute myocarditis can occur concurrently with hepatitis, pancreatitis, nephritis, and encephalitis; thus, determining the presence of other infectious lesions is necessary to provide appropriate treatment for the patient.

The Repertoire of Adenovirus in Human Disease: The Innocuous to the Deadly

Adenoviridae is a family of double-stranded DNA viruses that are a significant cause of upper respiratory tract infections in children and adults. Less commonly, the adenovirus family can cause a variety of gastrointestinal, ophthalmologic, genitourinary, and neurologic diseases. Most adenovirus infections are self-limited in the immunocompetent host and are treated with supportive measures. Fatal infections can occur in immunocompromised patients and less frequently in the healthy. Adenoviral vectors are being studied for novel biomedical applications including gene therapy and immunization. In this review we will focus on the spectrum of adenoviral infections in humans.

Characterization of rhinovirus C from a 4-year-old boy with acute onset dilated cardiomyopathy in Jakarta, Indonesia

Introduction

Myocarditis, inflammation of the heart muscle, can be caused by infections, autoimmune disease or exposure to toxins. The major cause of myocarditis in the paediatric population is viral infection, including coxsackievirus B3, adenovirus, herpesvirus, parvovirus, influenza A and B, and hepatitis. Here, we report the detection of rhinovirus C in a boy with a clinical presentation of myocarditis, suggesting a possible causative role of this virus in this case.

Case presentation

A previously well 4.5-year-old boy presented with increasing breathlessness for a week prior to admission. He also had upper respiratory tract infection a few days before the event. An echocardiogram revealed severe left ventricle (LV) systolic dysfunction with dilation of the LV. RNA was extracted from serum and two nasal swabs, and tested with conventional PCR at the family level for viruses including enterovirus, dengue, chikungunya, influenza, herpesvirus, paramyxovirus and coronavirus. Further characterization of the enterovirus group was carried out using PCR with primers targeting the VP4/VP2 gene, followed by sequencing. Molecular tests showed the presence of rhinovirus C genetic material in both serum and swab samples. Phylogenetic analysis of the VP4/VP2 region showed 96-97 % similarity with the closest strain isolated in Ulaanbaatar (Mongolia) and Japan in 2012.

Conclusion

We report the possible association of rhinovirus C and myocarditis in a child presenting with acute onset of dilated cardiomyopathy.

Intravenous immunoglobulins in children with new onset dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy is a rare but serious disorder in children. No effective diagnostic or treatment tools are readily available. This study aimed to evaluate the efficacy of intravenous immunoglobulins in children with new onset dilated cardiomyopathy. Methods and results In this retrospective cohort study, 94 children with new onset dilated cardiomyopathy were followed during a median period of 33 months. All patients with secondary dilated cardiomyopathy - for example, genetic, auto-immune or structural defects - had been excluded. Viral tests were performed in all patients and 18 (19%) children met the criteria for the diagnosis "probable or definite viral myocarditis". Intravenous immunoglobulins were administered to 21 (22%) patients. Overall transplant-free survival was 75% in 5 years and did not differ between treatment groups. The treatment was associated with a higher recovery rate within 5 years, compared with non-treated children (70 versus 43%, log rank=0.045). After correction for possible confounders the hazard ratio for recovery with intravenous immunoglobulins was not significant (hazard ratio: 2.1; 95% CI: 1.0-4.6; p=0.056). Administration of intravenous immunoglobulins resulted in a greater improvement in the shortening fraction of the left ventricle.

CONCLUSION

In our population of children with new onset dilated cardiomyopathy, of either viral or idiopathic origin, intravenous immunoglobulins were administered to a minority of the patients and did not influence transplant-free survival, but were associated with better improvement of systolic left ventricular function and with better recovery. Our results support the concept that children with new onset dilated cardiomyopathy might benefit from intravenous immunoglobulins.

Viral Infection of the Heart: Pathogenesis and Diagnosis

Viral infections of the heart cause serious clinical problems, either as infectious myocarditis, which usually is a consequence of acute infection or as idiopathic dilated cardiomyopathy, resulting rather from a chronic infection. This minireview presents an up-to-date view on pathomechanisms of viral infection of the heart tissues, the role of immune system in controlling infectious process at its various stages and current possibilities of recognizing viral infection of the heart with use of both cardiological and virological methods. Our goal was to present the variety of known viral agents causing heart infection, level of complexity in mutual virus-cell interactions, and consequent clinical scenarios.

Virus myocarditis in a 1-month-old boy presenting as two types of paroxysmal supraventricular tachycardia

Herein we describe the case of a 1-month-old boy with acute viral myocarditis, who presented with two kinds of paroxysmal supraventricular tachycardia, and who was cured after medical treatment. He was brought to the emergency room with poor feeding due to fever. On the third day of hospitalization, a narrow QRS tachycardia (180-200 beats/min) was detected. Echocardiography showed a high echoic area at the atrial septum around the atrioventricular node. The patient was clinically diagnosed with acute myocarditis. The narrow QRS tachycardia was diagnosed as incessant junctional ectopic tachycardia. The patient was treated with propranolol and landiolol. The frequency of the tachycardia decreased, but a different narrow QRS tachycardia was detected on the 15th day of hospitalization on electrocardiogram (220 beats/min), which was ascribed to atrioventricular nodal re-entrant tachycardia. Atenolol was effective for the tachycardia. At 2 years follow up, cardiac function was normal and tachycardia had not recurred.

Right ventricular endomyocardial biopsy in children and adolescents with drug-refractory arrhythmia

Purpose This study aimed to assess the results of endomyocardial biopsy from the right ventricle to establish the possible cause for drug-refractory arrhythmias in children. Materials and methods We enrolled 19 consecutive young patients with drug-refractory arrhythmia, from 2010 to 2013, who underwent endomyocardial biopsy. Inclusion criteria were as follows: age <18 years with a structurally normal heart or mild changes in a structure of the heart initially diagnosed as arrhythmia-induced cardiomyopathy. Overall, 86 biopsies were performed in 19 patients. Histopathological analysis, immunohistochemistry, and polymerase chain reaction were used for the interpretation of the endomyocardial biopsy.

RESULTS

The mean age of the patient population was 14.1±2.9 year (range from 7 to 17 years). All these patients had a history of drug-refractory arrhythmia for >5 months (mean 30 months). Patients underwent a complete history investigation, physical examination, laboratory studies, echocardiography, electrocardiography, treadmill test, and Holter monitoring before endomyocardial biopsy; two patients with arrhythmogenic right ventricular dysplasia had implantable cardioverter defibrillator implantation and further appropriate successful device shocks. Myocarditis was diagnosed based on histopathological and immunohistological analyses in nine (47.4%) patients. Polymerase chain reaction was positive for viral genome in four of them; five patients had active myocarditis. Radiofrequency ablation was performed in 17 patients; five out of six (83%) endomyocardial biopsy-proved myocarditis patients had successful radiofrequency ablation. No significant complication was reported during ablation and endomyocardial biopsy.

CONCLUSIONS

Approximately half of the children with drug-refractory arrhythmia had unsuspected myocarditis according to the results of the endomyocardial biopsy.

Clinical applications of multi-parametric CMR in myocarditis and systemic inflammatory diseases

Cardiac magnetic resonance (CMR) has changed the management of suspected viral myocarditis by providing a ‘positive’ diagnostic test and has lead to new insights into myocardial involvement in systemic inflammatory conditions. In this review we analyse the use of CMR tissue characterisation techniques across the available studies including T2 weighted imaging, early gadolinium enhancement, late gadolinium enhancement, Lake Louise Criteria, T2 mapping, T1 mapping and extracellular volume assessment. We also discuss the use of multiparametric CMR in acute cardiac transplant rejection and a variety of inflammatory conditions such as sarcoidosis, systemic lupus erythrematous, rheumatoid arthritis and systemic sclerosis.

Multivalent and Multipathogen Viral Vector Vaccines

The presentation and delivery of antigens are crucial for inducing immunity and, desirably, lifelong protection. Recombinant viral vectors-proven safe and successful in veterinary vaccine applications-are ideal shuttles to deliver foreign proteins to induce an immune response with protective antibody levels by mimicking natural infection. Some examples of viral vectors are adenoviruses, measles virus, or poxviruses. The required attributes to qualify as a vaccine vector are as follows: stable insertion of coding sequences into the genome, induction of a protective immune response, a proven safety record, and the potential for large-scale production. The need to develop new vaccines for infectious diseases, increase vaccine accessibility, reduce health costs, and simplify overloaded immunization schedules has driven the idea to combine antigens from the same or various pathogens. To protect effectively, some vaccines require multiple antigens of one pathogen or different pathogen serotypes/serogroups in combination (multivalent or polyvalent vaccines). Future multivalent vaccine candidates are likely to be required for complex diseases like malaria and HIV. Other novel strategies propose an antigen combination of different pathogens to protect against several diseases at once (multidisease or multipathogen vaccines).

Myocarditis in Paediatric Patients: Unveiling the Progression to Dilated Cardiomyopathy and Heart Failure

Myocarditis is a challenging and potentially life-threatening disease associated with high morbidity in some paediatric patients, due to its ability to present as an acute and fulminant disease and to ultimately progress to dilated cardiomyopathy. It has been described as an inflammatory disease of the myocardium caused by diverse aetiologies. Viral infection is the most frequent cause of myocarditis in developed countries, but bacterial and protozoal infections or drug hypersensitivity may also be causative agents. The prompt diagnosis in paediatric patients is difficult, as the spectrum of clinical manifestation can range from no myocardial dysfunction to sudden cardiac death. Recent studies on myocarditis pathogenesis have revealed a triphasic nature of this disease, which influences the diagnostic and therapeutic strategies to adopt in each patient. Endomyocardial biopsy remains the gold standard for diagnosing myocarditis, and several non-invasive diagnostic tools can be used to support the diagnosis. Intravenous immunoglobulin has become part of routine practice in the treatment of myocarditis in paediatric patients at many centres, but its true effect on the cardiac function has been the target of many studies. The aim of this review is to approach the recently discovered facets of paediatric myocarditis regarding its progression to dilated cardiomyopathy.

Recommendations for participation in competitive sport and leisure-time physical activity in individuals with cardiomyopathies, myocarditis and pericarditis

Several relatively uncommon, but important cardiovascular diseases are associated with increased risk for acute cardiac events during exercise (including sudden death), such as hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and myo-pericarditis. Practising cardiologists are frequently asked to advise on exercise programmes and sport participation in young individuals with these cardiovascular diseases. Indeed, many asymptomatic (or mildly symptomatic) patients with cardiomyopathies aspire to a physically active lifestyle to take advantage of the many documented benefits of exercise. While recommendations dictating the participation in competitive sport for athletes with cardiomyopathies and myo-pericarditis have recently been published as a consensus document of the European Society of Cardiology, no European guidelines have addressed the possible participation of patients with cardiomyopathies in recreational and amateur sport activities. The present document is intended to offer a comprehensive overview to practising cardiologists and sport physicians of the recommendations governing safe participation in different types of competitive sport, as well as the participation in a variety of recreational physical activities and amateur sports in individuals with cardiomyopathies and myo-pericarditis. These recommendations, based largely on the experience and insights of the expert panel appointed by the European Society of Cardiology, include the most up-to-date information concerning regular exercise and sports activity in patients with cardiomyopathies and myo-pericarditis.

Interferon-dependent immunoproteasome activity during mouse adenovirus type 1 infection

The immunoproteasome is an inducible host mechanism that aids in the clearance of damaged proteins. The immunoproteasome also influences immune function by enhancing peptide presentation by MHC class I and promotes inflammation via IκB degradation and activation of NF-κB. We used mouse adenovirus type 1 (MAV-1) to characterize the role of the immunoproteasome in adenovirus pathogenesis. Following intranasal infection of mice, immunoproteasome activity in the heart and lung was significantly increased in an IFN-γ-dependent manner. Absence of the β5i immunoproteasome subunit and pharmacological inhibition of β5i activity had minimal effects on viral replication, virus-induced cellular inflammation, or induction of cytokine expression. Likewise, the establishment of protective immunity following primary infection was not significantly altered by β5i deficiency. Thus, although immunoproteasome activity is robustly induced during acute infection with MAV-1, our data suggest that other mechanisms are capable of compensating for immunoproteasome activity to maintain antiviral immunity and appropriate inflammatory responses.

Role of coxsackievirus and adenovirus receptor (CAR) expression and viral load of adenovirus and enterovirus in patients with dilated cardiomyopathy

Enteroviruses (EVs) and adenoviruses (AdVs) are two important etiological agents of viral myocarditis and dilated cardiomyopathy (DCM). Both these viruses share a common receptor, the coxsackievirus and adenovirus receptor (CAR), for their infection. However, the role of viral load and CAR expression in disease severity has not yet been completely elucidated. The present study aimed to determine viral load of EV and AdV in DCM patients and correlate them with the level of CAR expression in these patients. Sixty-three DCM cases and 30 controls, each of whom died of heart disease other than DCM and non-cardiac disease respectively, were included. Viral load was determined by TaqMan real-time PCR using primers and probes specific for the AdV hexon gene and the 5'UTR region of EV. The CAR mRNA level was semi-quantitated by RT-PCR, and antigen expression was studied by immunohistochemistry. A significantly high AdV load (p < 0.05) and CAR expression (p < 0.05) were observed in DCM cases versus controls, whereas the EV load showed no significant difference. The data suggests a clinical threshold of 128 AdV copies/500 ng of DNA for DCM, with 66.7 % sensitivity and 65 % specificity. A positive correlation between AdV load and CAR expression (p < 0.001) was also observed in DCM cases. The high adenoviral load and increased CAR expression in DCM and their association with adverse disease outcome indicates role of both virus and receptor in disease pathogenesis. Thus, the need for targeting both the virus and the receptor for treatment of viral myocarditis and early DCM requires further confirmation with larger studies.

Proinflammatory effects of interferon gamma in mouse adenovirus 1 myocarditis

Adenoviruses are frequent causes of pediatric myocarditis. Little is known about the pathogenesis of adenovirus myocarditis, and the species specificity of human adenoviruses has limited the development of animal models, which is a significant barrier to strategies for prevention or treatment. We have developed a mouse model of myocarditis following mouse adenovirus 1 (MAV-1) infection to study the pathogenic mechanisms of this important cause of pediatric myocarditis. Following intranasal infection of neonatal C57BL/6 mice, we detected viral replication and induction of interferon gamma (IFN-γ) in the hearts of infected mice. MAV-1 caused myocyte necrosis and induced substantial cellular inflammation that was composed predominantly of CD3(+) T lymphocytes. Depletion of IFN-γ during acute infection reduced cardiac inflammation in MAV-1-infected mice without affecting viral replication. We observed decreased contractility during acute infection of neonatal mice, and persistent viral infection in the heart was associated with cardiac remodeling and hypertrophy in adulthood. IFN-γ is a proinflammatory mediator during adenovirus-induced myocarditis, and persistent adenovirus infection may contribute to ongoing cardiac dysfunction.

IMPORTANCE

Studying the pathogenesis of myocarditis caused by different viruses is essential in order to characterize both virus-specific and generalized factors that contribute to disease. Very little is known about the pathogenesis of adenovirus myocarditis, which is a significant impediment to the development of treatment or prevention strategies. We used MAV-1 to establish a mouse model of human adenovirus myocarditis, providing the means to study host and pathogen factors contributing to adenovirus-induced cardiac disease during acute and persistent infection. The MAV-1 model will enable fundamental studies of viral myocarditis, including IFN-γ modulation as a therapeutic strategy.

Major alteration in coxsackievirus B3 genomic RNA structure distinguishes a virulent strain from an avirulent strain

Coxsackievirus B3 (CV-B3) is a cardiovirulent enterovirus that utilizes a 5′ untranslated region (5′UTR) to complete critical viral processes. Here, we directly compared the structure of a 5′UTR from a virulent strain with that of a naturally occurring avirulent strain. Using chemical probing analysis, we identified a structural difference between the two 5′UTRs in the highly substituted stem-loop II region (SLII). For the remainder of the 5′UTR, we observed conserved structure. Comparative sequence analysis of 170 closely related enteroviruses revealed that the SLII region lacks conservation. To investigate independent folding and function, two chimeric CV-B3 strains were created by exchanging nucleotides 104–184 and repeating the 5′UTR structural analysis. Neither the parent SLII nor the remaining domains of the background 5′UTR were structurally altered by the exchange, supporting an independent mechanism of folding and function. We show that the attenuated 5′UTR lacks structure in the SLII cardiovirulence determinant.

Classification and histological, immunohistochemical, and molecular diagnosis of inflammatory myocardial disease

In the WHO 1996 classification of cardiomyopathies, myocarditis is defined as an "inflammatory disease of the myocardium associated with cardiac dysfunction" and is listed among "specific cardiomyopathies". Myocarditis is diagnosed on endomyocardial biopsy (EMB) by established histological, immunological, and immunohistochemical criteria, and molecular techniques are recommended to identify viral etiology. Infectious, autoimmune, and idiopathic forms of inflammatory cardiomyopathy are recognized that may lead to dilated cardiomyopathy. According to Dallas criteria, myocarditis is diagnosed in the setting of an "inflammatory infiltrate of the myocardium with necrosis and/or degeneration of adjacent myocytes, not typical of ischemic damage associated with coronary artery disease". The majority of experts in the field agree that an actual increase in sensitivity of EMB has now been reached by using immunohistochemistry together with histology. A value of >14 leukocytes/mm(2) with the presence of T lymphocytes >7 cells/mm(2) has been considered a realistic cut off to reach a diagnosis of myocarditis. The development of molecular biological techniques, particularly amplification methods like polymerase chain reaction (PCR) or nested-PCR, allows the detection of low copy viral genomes even from an extremely small amount of tissue such as in EMB specimens. Positive PCR results obtained on EMB should always be accompanied by a parallel investigation on blood samples collected at the time of the EMB. According to the recent Association for European Cardiovascular Pathology guidelines, optimal specimen procurement and triage indicates at least three, preferably four, EMB fragments, each 1-2 mm in size, that should immediately be fixed in 10 % buffered formalin at room temperature for light microscopic examination. In expected focal myocardial lesions, additional sampling is recommended. Moreover, one or two specimens should be snap-frozen in liquid nitrogen and stored at -80 °C or alternatively stored in RNA-later for possible molecular tests or specific stains. A sample of peripheral blood (5-10 ml) in EDTA or citrate from patients with suspected myocarditis allows molecular testing for the same viral genomes sought in the myocardial tissue.

The presence of enterovirus, adenovirus, and parvovirus B19 in myocardial tissue samples from autopsies: an evaluation of their frequencies in deceased individuals with myocarditis and in non-inflamed control hearts

PURPOSE

Multiple viruses have been detected in cardiac tissue, but their role in causing myocarditis remains controversial. Viral diagnostics are increasingly used in forensic medicine, but the interpretation of the results can sometimes be challenging. In this study, we examined the prevalence of adenovirus, enterovirus, and parvovirus B19 (PVB) in myocardial autopsy samples from myocarditis related deaths and in non-inflamed control hearts in an effort to clarify their significance as the causes of myocarditis in a forensic material.

METHODS

We collected all autopsy cases diagnosed with myocarditis from 1992 to 2010. Eighty-four suicidal deaths with morphologically normal hearts served as controls. Polymerase chain reaction was used for the detection of the viral genomes (adenovirus, enterovirus, and PVB) in myocardial tissue specimens. The distinction between acute and persistent PVB infection was made by the serological determination of PVB-specific immunoglobulins M and G.

RESULTS

PVB was detected in 33 of 112 (29 %) myocarditis cases and 37 of 84 (44 %) control cases. All of the samples were negative for the presence of adenovirus and enterovirus. Serological evidence of an acute PVB infection, determined by the presence of immunoglobulin M, was only present in one case. In the remaining cases, PVB was considered to be a bystander with no or limited association to myocardial inflammation.

CONCLUSION

In this study, adenovirus, enterovirus, and PVB were found to be rare causes of myocarditis. The detection of PVB in myocardial autopsy samples most likely represents a persistent infection with no or limited association with myocardial inflammation. The forensic investigation of myocardial inflammation demands a thorough examination, including special attention to non-viral causes and requires a multidisciplinary approach.

Viral endomyocardial infection in the 1st year post transplant is associated with persistent inflammation in children who have undergone cardiac transplant

BACKGROUND

Viral genome in cardiac allograft has been associated with early graft loss in children who have undergone cardiac transplant from unknown mechanisms.

METHODS

This study is a retrospective review of children who have undergone cardiac transplant at a single institution from 1/2004 to 5/2008. Patients underwent cardiac catheterisations with endomyocardial biopsies to evaluate for rejection--graded on Texas Heart Institute scale--and the presence of virus by polymerase chain reaction. Patients with virus identified during the first year post transplant were compared at 1 year post transplant with virus-free patients.

RESULTS

The cohort comprised 59 patients, and the median age at transplant was 5.1 years. Viral genomes were isolated from 18 (31%) patients. The PCR + group had increased inflammation on endomyocardial biopsies, with a median score of 4 (ISHLT IR) versus 1 (ISHLT 1R) in the PCR--group (p = 0.014). The PCR + group had a similar cardiac index (median 3.7 ml/min/m(2)), pulmonary capillary wedge pressure (median 10 mmHg), and pulmonary vascular resistance index (median 1.7 U m(2)) comparatively. PCR + patients were more likely to have experienced an episode of rejection (p = 0.004).

CONCLUSIONS

Children who developed viral endomyocardial infections after a cardiac transplant have increased allograft inflammation compared with virus-free patients. However, the haemodynamic profile is similar between the groups. The ongoing subclinical inflammation may contribute to the early graft loss associated with these patients.

Role of endomyocardial biopsy for children presenting with acute systolic heart failure

Myocarditis, an inflammatory disease of the heart, frequently results from viral infections, postviral immune-mediated responses, or both. It is a common cause of acute-onset systolic heart failure in children. Endomyocardial biopsy (EMB) remains the gold standard for the diagnosis of myocarditis. However, EMB is not performed for most myocarditis cases involving children in the United States. Clinical scenarios in which EMB results added unique prognostic data and guidance to therapy have been defined recently. This review outlines the role of EMB in the diagnosis and management of myocarditis for children presenting with acute-onset systolic heart failure.

Current state of knowledge on aetiology, diagnosis, management, and therapy of myocarditis: a position statement of the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases

In this position statement of the ESC Working Group on Myocardial and Pericardial Diseases an expert consensus group reviews the current knowledge on clinical presentation, diagnosis and treatment of myocarditis, and proposes new diagnostic criteria for clinically suspected myocarditis and its distinct biopsy-proven pathogenetic forms. The aims are to bridge the gap between clinical and tissue-based diagnosis, to improve management and provide a common reference point for future registries and multicentre randomised controlled trials of aetiology-driven treatment in inflammatory heart muscle disease.

Successful IVIG treatment of human parechovirus-associated dilated cardiomyopathy in an infant

Human parechoviruses (HPeVs) are closely related to human enteroviruses and exhibit many similarities in disease spectrum and symptoms. HPeV1 is most commonly associated with mild disease, but rare associations with severe disease such as myocarditis have been reported. Currently, no treatment is available for severe HPeV infections. In this case report we describe an infant with a severe, dilated cardiomyopathy in whom HPeV1 was revealed to be the only identifiable cause. The infant was treated with intravenous immunoglobulins (IVIGs) and recovered completely. In vivo blood samples revealed a high HPeV1 antibody titer after treatment with IVIGs. In vitro IVIGs contained high titers of neutralizing antibodies against HPeV1. Our hypothesis is that patients with myocarditis caused by viruses with a high prevalence in the population and hence high antibody titers in IVIGs are likely to benefit from treatment with IVIGs. More research combining virological and clinical data is needed to see whether this hypothesis is true.

Myocardial injury in patients with chronic hepatitis C infection

BACKGROUND & AIMS

The existence of a direct pathogenic link between hepatitis C virus (HCV) infection and myocardial injury has not been confirmed. We investigated the association between myocardial conditions and HCV in patients with HCV-related chronic hepatitis using thallium-201 myocardial scintigraphy.

METHODS

In 217 consecutive cases of chronic HCV infection without overt heart disease, we performed electrocardiography (ECG), echocardiography, serum tests on myocardial injury and thallium-201 myocardial scintigraphy. Myocardial injury was confirmed by severity score (SS), which was calculated as the sum of thallium-201 perfusion defect scores. SS was followed prior to and after interferon (IFN) therapy in 200 patients with chronic hepatitis C.

RESULTS

An abnormal ECG was found in 9% of the patients with chronic hepatitis C. Abnormal SS was found in 87% of the chronic hepatitis C patients. Independent factors related to higher pretreatment SS were histology activity index score, serum HCV RNA titer, and indocyanine green disappearance rate. After IFN therapy, SS was improved in patients with sustained virologic response. Among relapsers, SS improved at the initial disappearance of HCV RNA, but it worsened with the reappearance of HCV RNA. SS in non-viral responders did not change with IFN therapy.

CONCLUSIONS

Myocardial perfusion defects were found in 87% of the patients with chronic hepatitis C and improved with viral eradication with IFN therapy.

Myocarditis: diagnosis and treatment

OPINION STATEMENT

Myocarditis is a condition that can have a very wide clinical spectrum ranging from asymptomatic forms to fatal disease, but mostly presenting as new onset heart failure with reduced left ventricular ejection fraction, with or without viral syndrome. This condition is an important cause of sudden cardiac death in young patients. High risk features include second and third degree atrioventricular block or malignant arrhythmias. The diagnostic work-up may be challenging, but non-invasive imaging, primarily cardiac magnetic resonance, plays an increasingly important role, although endomyocardial biopsy is still considered a gold standard for diagnosis. Most importantly, myocarditis can transition to non-ischemic cardiomyopathy with eventually poor outcome. In this review, we will summarize the data on different diagnostic and treatment modalities of this disease.

Influenza A/H1N1 (2009) infection as a cause of unexpected out-of-hospital death in the young

Abstract:  In March 2009, a new strain of influenza A/H1N1 virus was identified in Mexico, responsible for a pandemic. Worldwide, more than 13,500 patients died, most often from acute respiratory distress syndrome. Because sudden death cases were rare, involving mostly young apparently healthy persons, influenza A/H1N1 (2009)‐related deaths may be misdiagnosed, which can raise medico‐legal issues. Case history: we report on an unexpected out‐of‐hospital death involving a young male with no past medical history and no vaccination. Fever was his only symptom. Laboratory tests: histology showed patchy necrotic foci with mononuclear inflammation in the lungs. The heart was histologically normal, but virological analyses using molecular biology on frozen myocardial samples showed high virus load. In conclusion, this case report shows that influenza A/H1N1 (2009) virus can be a cause of sudden cardiac death in the young and demonstrates the importance of quantitative virological analyses for the diagnosis of myocarditis.

Comparison of the clinical presentation, treatment, and outcome of fulminant and acute myocarditis in children

BACKGROUND

Myocarditis (MC) is an important cause of cardiac dysfunction in children. Fulminant MC is sometimes fatal, and sequelae may develop during follow-up. We conducted a nationwide survey to determine the clinico-epidemiological features of MC in Japanese children and adolescents.

METHODS AND RESULTS

Survey questionnaires were mailed to 627 hospitals, which were asked if they had treated MC patients aged between 1 month and 17 years during the period from January 1997 through December 2002. Responses were collected until December 2005, and data were collected and analyzed until January 2008. A total of 169 patients were reported: 64 fulminant cases, 89 acute cases, and 8 chronic cases. Incidence was 43.5 cases/year and 0.26 cases/100,000. Pathogens were identified in 37 patients; coxsackie virus accounted for 60%. Major cardiovascular manifestations at onset were congestive heart failure, refractory arrhythmia, and syncope in 70, 37, and 17 patients, respectively. Intravenous immunoglobulin was administered to 73 patients. Mechanical support seemed to be effective and life-saving. Among the 169 patients, 123 survived. Cardiovascular sequelae were reported in 49 patients.

CONCLUSIONS

The survival rate for children with fulminant MC was disappointing. Overall, two-thirds of survivors had no sequelae. Mechanical support may reduce the mortality and the risk of clinical worsening.

MiR-342-5p suppresses coxsackievirus B3 biosynthesis by targeting the 2C-coding region

Coxsackievirus B type 3 (CVB3) is one of the major pathogens associated with human heart disease. miRNAs are a class of short, noncoding RNA that can post-transcriptionally modulate gene expression. By comparing the CVB3 genome and miR-342-5p sequences, we found there were potential miR-342-5p targets in the CVB3 genome. To verify the effect of miR-342-5p on CVB3 biosynthesis, HeLa cells were infected with a Renilla luciferase (RLuc)-expressing CVB3 variant (RLuc-CVB3). We observed that miR-342-5p could significantly inhibit the expression of RLuc in infected cells. In HeLa cells infected with an enhanced green fluorescence protein (EGFP)-expressing CVB3 variant (EGFP-CVB3), EGFP expression was also significantly inhibited by miR-342-5p. The inhibitory effect of miR-342-5p on EGFP expression in EGFP-CVB3-infected cells could be reversed by transfection with anti-miR-342-5p oligonucleotide (AMO-miR-342-5p). Moreover, RNA and protein biosynthesis in wild-type CVB3 was significantly inhibited by miR-342-5p. By mutating the putative targets of miR-342-5p in the 2C-coding region, a sequence, nt4989-nt5015, was identified as the miR-342-5p target. The conserved nt4989-nt5015 sequences of CVB type 1-5 suggest miR-342-5p may exert its inhibitory effect in other types of coxsackievirus besides CVB3. Western blotting indicated that miR-342-5p could indeed suppress protein expression in CVB type 1 and 5. There was a moderate abundance of miR-342-5p in the gut, heart, and brain of Balb/c mice, suggesting that miR-342-5p may interact with CVB3 in vivo. Taken together, these results indicate that miR-342-5p can inhibit CVB3 biosynthesis by targeting its 2C-coding region and therefore may be a potential therapeutic agent in the treatment of CVB3 infection.

A single-amino-acid polymorphism in reovirus protein μ2 determines repression of interferon signaling and modulates myocarditis. J Virol. 2012;86:2302-2311. [PMID: 22156521 DOI: 10.1128/jvi.06236-11]

Myocarditis is indicated as the second leading cause of sudden death in young adults. Reovirus induces myocarditis in neonatal mice, providing a tractable model system for investigation of this important disease. Alpha/beta-interferon (IFN-α/β) treatment improves cardiac function and inhibits viral replication in patients with chronic myocarditis, and the host IFN-α/β response is a determinant of reovirus strain-specific differences in induction of myocarditis. Virus-induced IFN-β stimulates a signaling cascade that establishes an antiviral state and further induces IFN-α/β through an amplification loop. Reovirus strain-specific differences in induction of and sensitivity to IFN-α/β are associated with the viral M1, L2, and S2 genes. The reovirus M1 gene-encoded μ2 protein is a strain-specific repressor of IFN-β signaling, providing one possible mechanism for the variation in resistance to IFN and induction of myocarditis between different reovirus strains. We report here that μ2 amino acid 208 determines repression of IFN-β signaling and modulates reovirus induction of IFN-β in cardiac myocytes. Moreover, μ2 amino acid 208 determines reovirus replication, both in initially infected cardiac myocytes and after viral spread, by regulating the IFN-β response. Amino acid 208 of μ2 also influences the cytopathic effect in cardiac myocytes after spread. Finally, μ2 amino acid 208 modulates myocarditis in neonatal mice. Thus, repression of IFN-β signaling mediated by reovirus μ2 amino acid 208 is a determinant of the IFN-β response, viral replication and damage in cardiac myocytes, and myocarditis. These results demonstrate that a single amino acid difference between viruses can dictate virus strain-specific differences in suppression of the host IFN-β response and, consequently, damage to the heart.

Evaluation of type-specific real-time PCR assays using the LightCycler and J.B.A.I.D.S. for detection of adenoviruses in species HAdV-C

Sporadically, HAdVs from species HAdV-C are detected in acute respiratory disease outbreaks. To rapidly type these viruses, we designed real-time PCR assays that detect and discriminate between adenovirus types HAdV-C1, -C2, -C5, and -C6. Sixteen clinical isolates from the California Department of Public Health were used to validate the new assays. Type-specific TaqMan real-time PCR assays were designed and used independently to successfully identify 16 representative specimens. The lower limit of detection for our LightCycler singleplex real-time PCR assays were calculated to be 100, 100, 100, and 50 genomic copies per reaction for HAdV-C1, HAdV-C2, HAdV-C5 and HAdV-C6, respectively. The results for the singleplex J.B.A.I.D.S. assays were similar. Our assays did not cross-react with other adenoviruses outside of species HAdV-C, respiratory syncytial virus, influenza, or respiratory disease causing bacteria. These assays have the potential to be useful as diagnostic tools for species HAdV-C infection.

The management of myocarditis

Despite considerable advances in our understanding of myocarditis pathogenesis, the clinical management of myocarditis has changed relatively little in the last few years. This review aims to help bridge the widening gap between recent mechanistic insights, which are largely derived from animal models, and their potential impact on disease burden. We illustrate the pathogenetic mechanisms that are prime targets for novel therapeutic interventions. Pathway and pathogen-specific molecular diagnostic tests have expanded the role for endomyocardial biopsy. State of the art cardiac magnetic resonance imaging can now provide non-invasive tissue characterization and localize inflammatory infiltrates but imaging techniques are misleading if infectious agents are involved. We emphasize the gaps in our current clinical knowledge, particularly with respect to aetiology-based therapy, and suggest opportunities for high impact, translational investigations.

State of the art in forensic investigation of sudden cardiac death

The sudden death of a young person is a devastating event for both the family and community. Over the last decade, significant advances have been made in understanding both the clinical and genetic basis of sudden cardiac death. Many of the causes of sudden death are due to genetic heart disorders, which can lead to both structural (eg, hypertrophic cardiomyopathy) and arrhythmogenic abnormalities (eg, familial long QT syndrome, Brugada syndrome). Most commonly, sudden cardiac death can be the first presentation of an underlying heart problem, leaving the family at a loss as to why an otherwise healthy young person has died. Not only is this a tragic event for those involved, but it also presents a great challenge to the forensic pathologist involved in the management of the surviving family members. Evaluation of families requires a multidisciplinary approach, which should include cardiologists, a clinical geneticist, a genetic counselor, and the forensic pathologist directly involved in the sudden death case. This multifaceted cardiac genetic service is crucial in the evaluation and management of the clinical, genetic, psychological, and social complexities observed in families in which there has been a young sudden cardiac death. The present study will address the spectrum of structural substrates of cardiac sudden death with particular emphasis given to the possible role of forensic molecular biology techniques in identifying subtle or even merely functional disorders accounting for electrical instability.

The evolving approach to paediatric myocarditis: a review of the current literature

Paediatric myocarditis remains challenging from the perspectives of diagnosis and management. Multiple aetiologies exist and the majority of cases appear to be related to viral illnesses. Enteroviruses are believed to be the most common cause, although cases related to adenovirus may be more frequent than suspected. The clinical presentation is extremely varied, ranging from asymptomatic to sudden unexpected death. A high index of suspicion is crucial. There is emerging evidence to support investigations such as serum N-terminal B-type natriuretic peptide levels, as well as cardiac magnetic resonance imaging as adjuncts to the clinical diagnosis. In the future, these may reduce the necessity for invasive methods, such as endomyocardial biopsy, which remain the gold standard. Management generally includes supportive care, consisting of cardiac failure medical management, with the potential for mechanical support and cardiac transplantation. Treatments aimed at immunosuppression remain controversial. The paediatric literature is extremely limited with no conclusive evidence to support or refute these strategies. This article summarises the current literature regarding aetiology, clinical presentation, diagnosis, and management of myocarditis in paediatric patients.