Antimyosin scintigraphy and immunohistologic analysis of endomyocardial biopsy in patients with clinically suspected myocarditis--evidence of myocardial cell damage and inflammation in the absence of histologic signs of myocarditis

A Review of the Role of Imaging Modalities in the Evaluation of Viral Myocarditis with a Special Focus on COVID-19-Related Myocarditis

Viral myocarditis is inflammation of the myocardium secondary to viral infection. The clinical presentation of viral myocarditis is very heterogeneous and can range from nonspecific symptoms of malaise and fatigue in subclinical disease to a more florid presentation, such as acute cardiogenic shock and sudden cardiac death in severe cases. The accurate and prompt diagnosis of viral myocarditis is very challenging. Endomyocardial biopsy is considered to be the gold standard test to confirm viral myocarditis; however, it is an invasive procedure, and the sensitivity is low when myocardial involvement is focal. Cardiac imaging hence plays an essential role in the noninvasive evaluation of viral myocarditis. The current coronavirus disease 2019 (COVID-19) pandemic has generated considerable interest in the use of imaging in the early detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related myocarditis. This article reviews the role of various cardiac imaging modalities used in the diagnosis and assessment of viral myocarditis, including COVID-19-related myocarditis.

Acute Myocarditis in Children: An Overview of Treatment and Recent Patents

BACKGROUND

Pediatric myocarditis is rare but challenging. This overview summarized the current knowledge and recent patents on childhood myocarditis.

METHODS

Clinical queries and keywords of "myocarditis" and "childhood" were used as search engine.

RESULTS

Viral infections are the most common causes of acute myocarditis. Affected children often have a prodrome of fever, malaise, and myalgia. Clinical manifestations of acute myocarditis in children can be nonspecific. Some children may present with easy fatigability, poor appetite, vomiting, abdominal pain, exercise intolerance, respiratory distress/tachypnea, dyspnea at rest, orthopnea, chronic cough with wheezing, chest pain, unexplained tachycardia, hypotension, syncope, and hepatomegaly. Supraventricular arrhythmias, ventricular arrhythmias, and heart block may be present. A subset of patients have fulminant myocarditis and present with cardiovascular collapse, which may progress to severe cardiogenic shock, and even death. A high index of suspicion is crucial to its diagnosis and timely management. Cardiac magnetic resonance imaging is important in aiding clinical diagnosis while, endomyocardial biopsy remains the gold standard. The treatment consists of supportive therapy, ranging from supplemental oxygen and fluid restriction to mechanical circulatory support. Angiotensinconverting enzyme inhibitors, angio-tensin II receptor blockers, β-blockers, and aldosterone antagonists might be used for the treatment of heart failure while, immunosuppression treatments remain controversial. There are a few recent patents targeting prevention or treatment of viral myocarditis, including an immunogenic composition comprising a PCV-2 antigen, glutathione-S-transferase P1, neuregulins, NF-[kappa] B inhibitor, a pharmaceutical composition which contains 2-amino-2- (2- (4-octyl phenyl) - ethyl) propane 1,3-diol, a composition containing pycnojenol, Chinese herbal concoctions, and a Korean oral rapamycin. Evidence of their efficacy is still lacking.

CONCLUSION

This article reviews the current literature regarding etiology, clinical manifestations, diagnosis, and management of acute myocarditis in children.

Myocardial Involvement in Rheumatic Disorders

PURPOSE OF REVIEW

Autoimmune rheumatic diseases (ARDs) affect 8% of the population and approximately 78% of patients are women. Myocardial disease in ARDs is the endpoint of various pathophysiologic mechanisms including atherosclerosis, valvular disease, systemic, myocardial, and/or vascular inflammation, as well as myocardial ischemia and replacement/diffuse fibrosis.

RECENT FINDINGS

The increased risk of CVD in ARDs leads to excess comorbidity not fully explained by traditional cardiovascular risk factors. It seems that the chronic inflammatory status typically seen in ARDs, promotes both the development of myocardial inflammation/fibrosis and the acceleration of atherosclerosis. CMR (cardio-vascular magnetic resonance) is the ideal imaging modality for the evaluation of cardiac involvement in patients with ARDs, as it can simultaneously assess cardiac function and characterize myocardial tissues with regard to oedema and fibrosis. Due to its high spatial resolution, CMR is capable of identifying various disease entities such as myocardial oedema /inflammation, subendocardial vasculitis and myocardial fibrosis, that are often missed by other imaging modalities, notably at an early stage of development. Although generally accepted guidelines about the application of CMR in ARDs have not yet been formulated, according to our experience and the available published literature, we recommend CMR in ARD patientS with new-onset heart failure (HF), arrhythmia, for treatment evaluation/change or if there is any mismatch between patient symptoms and routine non-invasive evaluation.

Recognition and Initial Management of Fulminant Myocarditis: A Scientific Statement From the American Heart Association

Fulminant myocarditis (FM) is an uncommon syndrome characterized by sudden and severe diffuse cardiac inflammation often leading to death resulting from cardiogenic shock, ventricular arrhythmias, or multiorgan system failure. Historically, FM was almost exclusively diagnosed at autopsy. By definition, all patients with FM will need some form of inotropic or mechanical circulatory support to maintain end-organ perfusion until transplantation or recovery. Specific subtypes of FM may respond to immunomodulatory therapy in addition to guideline-directed medical care. Despite the increasing availability of circulatory support, orthotopic heart transplantation, and disease-specific treatments, patients with FM experience significant morbidity and mortality as a result of a delay in diagnosis and initiation of circulatory support and lack of appropriately trained specialists to manage the condition. This scientific statement outlines the resources necessary to manage the spectrum of FM, including extracorporeal life support, percutaneous and durable ventricular assist devices, transplantation capabilities, and specialists in advanced heart failure, cardiothoracic surgery, cardiac pathology, immunology, and infectious disease. Education of frontline providers who are most likely to encounter FM first is essential to increase timely access to appropriately resourced facilities, to prevent multiorgan system failure, and to tailor disease-specific therapy as early as possible in the disease process.

The Clinical and Histological Spectrum of Idiopathic Inflammatory Myopathies

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of myositis, characterised by chronic muscle weakness, cutaneous features, different extra-muscular manifestations and circulating autoantibodies. IIMs included classical polymyositis (PM), dermatomyositis (DM) and other different types of myositis with a wide range of muscle involvement. A complete autoantibody profile and a muscle biopsy are mandatory to correctly diagnose different clinical entities and to define their different prognosis. Bohan and Peter's criteria included five items to diagnose adult onset PM and DM. The sensitivity was 74-100 %, while the specificity is low, due to a poor ability to differentiate PM from neuromuscular diseases. Other criteria included a more accurate histological definition of PM, DM or amyopathic DM, obtaining a higher specificity. Autoantibodies' association, interstitial lung disease and clinical cardiac involvement represent the main items that could define the prognosis of these patients. On the other hand, inclusion body myositis is a different myopathy characterised by a peculiar muscle mass involvement, muscle atrophy and progressive loss of function, due to complete failure to all immunosuppressive drugs used. Treatment of IIMs is based on corticosteroids (CS), which show rapid clinical response and functional improvement. Different immunosuppressant drugs are given to obtain a better control of the disease during CS tapering dose. No controlled double blind trials demonstrated the superiority of one immunesuppressant on another. The occurrence of interstitial lung involvement requires the immediate introduction of immunosuppressants in addiction to CS. Severe dysphagia seems to improve with intravenous immunoglobulins (Ig). Physical therapy could be started after the acute phase of diseases and seems to have a beneficial role in muscle strength recovery.

How to approach the great mimic? Improving techniques for the diagnosis of myocarditis

Myocarditis is characterized by inflammation of the myocardium, assessed by histological, immunological and immunohistochemical criteria, due to exogenous or endogenous causes. Abnormal QRS, increased troponin T and left ventricular regional or global dysfunction may be detected. Strain Doppler echocardiography can detect longitudinal segmental dysfunction of the myocardium, due to edema, which is in agreement with cardiac magnetic resonance imaging. Nuclear imaging shows a good sensitivity, but carries serious limitations. Somatostatin receptor positron emission tomography/computed tomography seems promising. Cardiac magnetic resonance imaging, using T2-weighted, early T1-weighted, delayed enhanced images and recently T2 and T1 mapping, has the best diagnostic capability. Endomyocardial biopsy has further contributed to the etiologic diagnosis of myocarditis. To conclude, cardiac magnetic resonance and endomyocardial biopsy have both significantly increased our diagnostic performance. However, further assessment by multicenter studies is needed to establish a clinically useful algorithm.

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.

Heart involvement in rheumatoid arthritis: multimodality imaging and the emerging role of cardiac magnetic resonance

OBJECTIVES

Patients with rheumatoid arthritis (RA) exhibit a high risk of cardiovascular disease (CVD). CVD in RA can present in many guises, commonly detected at a subclinical level only.

METHODS

Modern imaging modalities that allow the noninvasive assessment of myocardial performance and are able to identify cardiac abnormalities in early asymptomatic stages may be useful tools in terms of screening, diagnostic evaluation, and risk stratification in RA.

RESULTS

The currently used imaging techniques are echocardiography, single-photon emission computed tomography (SPECT), and cardiac magnetic resonance (CMR). Between them, echocardiography provides information about cardiac function, valves, and perfusion; SPECT provides information about myocardial perfusion and carries a high amount of radiation; and CMR-the most promising imaging modality-evaluates myocardial function, inflammation, microvascular dysfunction, valvular disease, perfusion, and presence of scar. Depending on availability, expertise, and clinical queries, "right technique should be applied for the right patient at the right time."

CONCLUSIONS

In this review, we present a short overview of CVD in RA focusing on the clinical implication of multimodality imaging and mainly on the evolving role of CMR in identifying high-risk patients who could benefit from prevention strategies and early specific treatment targeting the heart. Advantages and disadvantages of each imaging technique in the evaluation of RA are discussed.

[Cardiac involvement in polymyositis]

Cardiovascular involvement in polymyositis constitutes a major cause of death. However, the cardiac location is rarely symptomatic and does not usually represent the principle clinical feature at the time of the initial presentation. We present here an unusual case of polymyositis with severe and polymorph cardiac disturbances that predominant the muscular signs.

Cardiological features in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) represent a heterogeneous group of autoimmune systemic diseases characterized by chronic muscle weakness and inflammatory cell infiltrates in skeletal muscle. The most frequent IIMs, such as adult-onset polymyositis and dermatomyositis, display a wide range of clinical manifestations other than myositis, including skin changes, Raynaud's phenomenon and interstitial lung disease. Cardiac involvement is now well recognized as a clinically important manifestation in patients with polymyositis or dermatomyositis, although its actual frequency is still uncertain. Cardiovascular complications represent one of the most frequent causes of death in myositis, apart from cancer and lung involvement. Despite the fact that clinical manifestations are relatively rare, asymptomatic cardiovascular features are frequently reported in patients with polydermatomyositis and dermatomyositis. They are characterized by isolated electrocardiographic changes, valve disease, coronary vasculitis, ischemic abnormalities, heart failure and myocarditis. Chronic inflammation producing myocyte degeneration, tissues fibrosis and vascular alterations can explain the majority of reported cardiac features in myositic patients. Although previous works reported an association between heart involvement and some myositis-specific autoantibodies (namely anti-signal recognition particle), electrocardiography, echocardiography and, where necessary, heart magnetic resonance remain the mainstay for diagnosing and monitoring myocardial inflammation in these diseases. Anyway, a complete multiorgan assessment and a careful analysis of autoantibodies should be performed in every patient in order to define any possible distinct disease entities with different prognosis within the spectrum of IIMs.

Non-invasive imaging in the diagnosis of acute viral myocarditis

Autopsy series of consecutive cases have demonstrated an incidence of myocarditis at approximately 1–10%; on the contrary, myocarditis is seriously underdiagnosed clinically. In a traditional view, the gold standard has been myocardial biopsy. However, it is generally specific but invasive and less sensitive, mostly because of the focal nature of the disease. Thus, non-invasive approaches to detect myocarditis are necessary. The traditional diagnostic tools are electrocardiography, laboratory values, especially troponin T or I, creatine kinase and echocardiography. For a long period, nuclear technique with indium-111 antimyosin antibody has been used as a diagnostic approach. In the last years, the use of this technique has declined because of radiation exposure and 48-h delay in obtaining imaging after injection to prevent blood pool effect. Thus, a non-invasive diagnostic approach without radiation and online image availability has been awaited. Cardiac magnetic resonance imaging has these promising characteristics. With this technique, it is possible to analyse inflammation, oedema and necrosis in addition to functional parameters such as left ventricular function, regional wall motion and dimensions. Thus, cardiovascular magnetic resonance imaging has emerged as the most important imaging tool in the diagnostic procedure and the review focus on this field. But there are also advances in echocardiography and computer tomography, which are described in detail.

High prevalence of chronic myocarditis in dilated cardiomyopathy referred for left ventriculoplasty: expression of tenascin C as a possible marker for inflammation

The objectives of this study were to analyze the incidence of chronic myocarditis in dilated cardiomyopathy and to evaluate the diagnostic value of tenascin C for assessing inflammatory activity in the resected myocardium. Dilated cardiomyopathy patients with chronic myocarditis have a poor clinical outcome despite recent advances in medical treatments. Therefore, a precise diagnosis of inflammatory activity is critical to ensuring appropriate therapy. Tenascin C is an extracellular matrix glycoprotein that plays an important role in tissue remodeling in various heart diseases. Myocardial samples obtained during left ventriculoplasty from 64 patients (50 +/- 13 years, 56 men and 8 women) with dilated cardiomyopathy were examined by immunostaining for tenascin C. Histologic diagnosis was based on the Dallas criteria modified by the International Society and Federation of Cardiology task force. Nine cases (14%) had active myocarditis, 21 (33%) had borderline myocarditis, and 34 (53%) had no myocarditis. Intense tenascin C expression was observed at the site of active inflammation, with abundant cell accumulation, and in organized granulation tissue during the resolving phase but not in scar tissue during the healing phase. The ratio of tenascin C-positive area to the whole myocardium in the active and borderline myocarditis groups was significantly greater than that in the noninflammatory group. These findings suggest a high prevalence of chronic myocarditis in dilated cardiomyopathy patients and that tenascin C may prove to be a useful marker for distinguishing inflammatory cardiomyopathy from other types of dilated cardiomyopathy.

Gated myocardial perfusion scintigraphy in children with myocarditis: can it be considered as an indicator of clinical outcome?

PURPOSE

Myocarditis is an inflammation of the heart muscle and represents a challenge for diagnosis and treatment. On account of the lack of sensitivity and specificity of routine cardiac tests, there is a need for accurate diagnostic imaging. The aim of this study is to review the role of gated 99Tc-methoxyisobutylisonitrile myocardial perfusion scintigraphy (G-MPS) in the diagnosis and follow-up of the patients with myocarditis in comparison with gallium scintigraphy.

MATERIALS AND METHODS

Thirteen patients with a clinical diagnosis of myocarditis were included in the study. All underwent rest G-MPS and the images were then evaluated by quantitative perfusion single-photon emission computed tomography and quantitative gated single photon emission computed tomography software program. Visual evaluation of perfusion was performed as well as analysis of motion with thickening function [expressed as summed rest score, summed motion score, and summed thickening score (STS)] with calculation of ejection fraction (EF) and lung-to-heart (L/H) ratio. Eight patients underwent 67Ga scintigraphy. Clinical, echocardiography, and cardiac enzymes (creatinine kinase-MB, myoglobulin, troponin T, brain natriuretic peptide) data were gathered from the patients' charts. Clinical outcome was grouped according to prognosis. Spearman's correlation (SC) test was used for comparison analysis.

RESULTS

Myocardial perfusion defects were observed in eight patients. Perfusion defects in the left ventricle involve a mean of 7.25% (range: 1-11%), whereas wall motion abnormality on G-MPS was more prominent, which showed to be a better marker for myocardial inflammation and necrosis. The 67Ga scintigraphy findings were normal in all, but two. The G-MPS EF (33+/-21%) was slightly lower than the echocardiography EF (40+/-15%), but with close correlation (SC coefficient: 0.635). Comparison of scintigraphic findings with clinical parameters showed that summed motion score with G-MPS EF and STS with L/H ratios were highly correlated (0.932 and 0.622, respectively). The maximum brain natriuretic peptide and L/H ratio with STS were highly correlated with the patients' outcomes (SC coefficient: -0.621, 0.821, and 0.579, respectively), as well.

CONCLUSION

Tc-methoxyisobutylisonitrile G-MPS is therefore helpful in providing additional diagnostic and prognostic information in patients with myocarditis.

Myopericarditis: Etiology, management, and prognosis

Acute pericarditis is often accompanied by some degree of myocarditis. In clinical practice both pericarditis and myocarditis coexist because they share common etiologic agents, mainly cardiotropic viruses. The term "myopericarditis" indicates a primarily "pericarditic syndrome" and it is responsible for the majority of cases. The clinical presentation is varied, reflecting the variability of myocardial involvement, that may be focal or diffuse, affecting any or all cardiac chambers. Probably many cases may be subclinical and subtle cardiac symptoms and signs may be overshadowed by the systemic manifestations of the viral infection. Echocardiography is essential for the diagnosis of left ventricular dysfunction in even subclinical cases and for follow-up of patients with apparently normal left ventricular function. Magnetic resonance imaging holds promise for an effective non-invasive diagnostic tool. Either for acute pericarditis or myopericarditis there is a lack for adequate controlled clinical trials. In myopericarditis the use of NSAID should be cautious, because in animal models of myocarditis, NSAID are not effective and may actually enhance the myocarditic process and increase mortality. In clinical practice lower anti-inflammatory doses are mainly considered to control symptoms. The natural history of myopericarditis in large populations is not known with accuracy. On follow-up, the majority of these cases had objective normalization of echocardiography, electrocardiography, laboratory testing, and functional status, although up to 14% may report atypical, non-limiting chest discomfort. Unfortunately, few data have been published on myopericarditis, the paper reviews current available evidence on the presentation, management, and prognosis of myopericarditis.

Noninvasive imaging in myocarditis

Increased recognition of the role of inflammation in acute and chronic dilated cardiomyopathy has revived an interest in noninvasive imaging for detection of myocarditis. Diagnostic strategies that are based on molecular imaging promise to further advance our understanding and improve diagnostic precision. This article reviews the strengths and limitations of common clinical tests used for the diagnosis of myocarditis, with a focus on the emerging role of cardiovascular magnetic resonance imaging. Novel imaging modalities that are currently in preclinical development are discussed with recommendations for future clinical research.

Effects of corticosteroids and immunosuppressors on idiopathic inflammatory myopathy related myocarditis evaluated by magnetic resonance imaging

BACKGROUND

Cardiac involvement in idiopathic inflammatory myopathy has been recognised as an important prognostic factor, but treatment remains empirical.

OBJECTIVE

To investigate the effects of corticosteroids and immunosuppressors on myocarditis in patients with inflammatory myopathies.

METHODS

Patients with inflammatory myositis of recent onset who had not received treatment were evaluated for associated myocarditis by magnetic resonance imaging (MRI) and reinvestigated after treatment with high dose corticosteroids and immunosuppressors.

RESULTS

Four patients with histologically proven myositis were included. Two patients with polymyositis had cardiac clinical symptoms. Two other patients with dermatomyositis and diffuse cutaneous systemic sclerosis-polymyositis overlap syndrome were asymptomatic. In three cases the usual conventional screening tests were normal. For all patients an area of contrast enhancement and hypokinesia detected by cardiac MRI was markedly reduced after treatment with corticosteroids and immunosuppressors for 6 months.

CONCLUSION

Treatment with intravenous methylprednisolone followed by prednisone and immunosuppressive therapy seems to be effective for treating myocardial involvement in patients with idiopathic inflammatory myopathies, either alone or presenting as overlap syndromes. Cardiovascular MRI is a non-invasive technique that may be a powerful tool for diagnosis and monitoring of myocardial inflammation in this setting.

The Evolving Role of Cardiovascular Magnetic Resonance Imaging in Nonischemic Cardiomyopathy

Over the last several years, the role of cardiac magnetic resonance imaging in the diagnosis and management of heart failure has been rapidly expanding. The techniques unrivaled flexibility, accuracy in defining ventricular structure and function, and capacity to characterize tissue makes it particularly well suited for the study of the nonischemic cardiomyopathies. In this article, we provide an overview of the existing literature highlighting the diagnostic utility and prognostic power of cardiac magnetic resonance imaging in the nonischemic cardiomyopathies.

The significance of autoimmunity in myocarditis

A growing body of evidence supports the view that some forms of human myocarditis and dilated cardiomyopathy result from a pathogenic autoimmune response. The evidence is based first on the presence of heart-specific antibodies in many patients with these diseases, including antibodies with demonstrated functional effects. These antibodies may be present before the onset of dilated cardiomyopathy and may be predictive of the course of disease in terms of deterioration of cardiac function. Depletion of the heart-specific antibodies by extracorporeal immunoadsorption may result in amelioration of disease in some patients, often continuing for long periods of time. Clinical investigations show that a subpopulation of patients with dilated cardiomyopathy benefit from immunosuppressive treatment. In one report, this subpopulation was identified as autoantibody-positive and virus-negative. Finally, animal experiments have shown that autoimmune myocarditis can be induced by viral infection and that this autoimmune response can be duplicated by immunization with a well-characterized antigen, cardiac myosin. Based on this evidence, we propose that some forms of dilated cardiomyopathy and myocarditis result from pathogenic autoimmune responses that represent the final common pathogenetic pathway of various infectious and even non-infectious injuries.

Diagnostic performance of cardiovascular magnetic resonance in patients with suspected acute myocarditis: comparison of different approaches

OBJECTIVES

The aim of this research was to identify the diagnostic performance of gadolinium-enhanced and T2-weighted cardiovascular magnetic resonance (CMR) in suspected acute myocarditis.

BACKGROUND

Acute myocarditis is difficult to diagnose; CMR provides various means to visualize myocardial inflammatory changes. A CMR approach with clear-cut diagnostic criteria would be desirable.

METHODS

We investigated 25 patients with suspected acute myocarditis (18 males, 44 +/- 17 years) and 23 healthy controls (13 males, 29 +/- 10 years). Cardiovascular magnetic resonance studies included the following sequences: 1) T2-weighted triple inversion recovery; 2) T1-weighted spin echo before and over 4 min after gadolinium injection; and 3) inversion recovery-gradient echo 10 min after gadolinium injection. Qualitative and quantitative image analysis was performed for: 1) focal and global T2 signal intensity (SI); 2) myocardial global relative enhancement (gRE); and 3) areas of late gadolinium enhancement (LGE).

RESULTS

Both global T2 SI and gRE were higher in patients than in controls (T2: 2.3 +/- 0.4 vs. 1.7 +/- 0.4; p < 0.0001, gRE: 6.8 +/- 4.0 vs. 3.7 +/- 2.3; p < 0.001). The sensitivity, specificity, and diagnostic accuracy for T2 (cutoff value of 1.9) were 84%, 74%, and 79%, respectively; gRE: (cutoff value of 4.0) 80%, 68%, and 74.5% respectively; LGE: 44%, 100%, and 71%, respectively. The best diagnostic performance was obtained when "any-two" of the three sequences were positive in the same patient yielding a 76% sensitivity, 95.5% specificity, and 85% diagnostic accuracy.

CONCLUSIONS

A combined CMR approach using T2-weighted imaging, early and late gadolinium enhancement, provides a high diagnostic accuracy and is a useful tool in the diagnosis and assessment of patients with suspected acute myocarditis.

Diagnostic utility of tenascin-C for evaluation of the activity of human acute myocarditis

Tenascin-C (TN-C) is an extracellular matrix protein that is expressed transiently in close association with tissue remodelling in various body sites. In the heart, TN-C is only present during early stages of development, is not expressed in the normal adult, but reappears in pathological states. The purpose of this study was to analyse the expression of TN-C in myocardial tissue from myocarditis patients, and to evaluate the diagnostic value of immunostaining for TN-C in the assessment of inflammatory activity in biopsy specimens. A total of 113 biopsy specimens obtained from 32 patients with a clinical diagnosis of acute myocarditis were examined by immunohistochemistry and in situ hybridization for TN-C. The immunostaining was semi-quantified and compared with histological diagnosis according to the Dallas criteria. Furthermore, serial biopsies from 22 patients were taken during convalescence, and sequential changes in TN-C levels were analysed. Expression of TN-C was specifically detected in endomyocardial biopsy specimens from patients with active-stage inflammation, and disappeared in healed stages. The degree of expression of TN-C correlated with the severity of histological lesions. These data suggest that TN-C reflects disease activity in cases of human myocarditis. Immunostaining for TN-C could enhance the sensitivity and accuracy of diagnosis using biopsy specimens.

Smallpox vaccination and myopericarditis: a clinical review

Smallpox is a devastating viral illness that was eradicated after an aggressive, widespread vaccination campaign. Routine U.S. childhood vaccinations ended in 1972, and routine military vaccinations ended in 1990. Recently, the threat of bioterrorist use of smallpox has revived the need for vaccination. Over 450,000 U.S. military personnel received the vaccination between December 2002 and June 2003, with rates of non-cardiac complications at or below historical levels. The rate of cardiac complications, however, has been higher than expected, with two confirmed cases and over 50 probable cases of myopericarditis after vaccination reported to the Department of Defense Smallpox Vaccination Program. The practicing physician should use the history and physical, electrocardiogram, and cardiac biomarkers in the initial evaluation of a post-vaccination patient with chest pain. Echocardiogram, cardiac catheterization, magnetic resonance imaging, nuclear imaging, and cardiac biopsy may be of use in further workup. Treatment is with non-steroidal anti-inflammatory agents, four to six weeks of limited exertion, and conventional heart failure treatment as necessary. Immune suppressant therapy with steroids may be uniquely beneficial in myopericarditis related to smallpox vaccination, compared with other types of myopericarditis. If a widespread vaccination program is undertaken in the future, many more cases of post-vaccinial myopericarditis could be seen. Practicing physicians should be aware that smallpox vaccine-associated myopericarditis is a real entity, and symptoms after vaccination should be appropriately evaluated, treated if necessary, and reported to the Vaccine Adverse Events Reporting System.

Immunomodulatory treatment strategies in inflammatory cardiomyopathy: current status and future perspectives

Chronic autoimmunity and viral persistence constitute prognostic factors for adverse outcome in dilated cardiomyopathy patients. Inflammatory cardiomyopathy is a specific cardiomyopathy entity diagnosed in approximately 50% of dilated cardiopmyopathy patients by immunohistological quantification of immunocompetent infiltrates and cell adhesion molecule abundance. Patients with autoimmune inflammatory cardiomyopathy benefit from immunosuppressive treatment and immunoadsorption by improvement of left ventricular ejection fraction and heart failure symptoms, paralleled by a significant suppression of intramyocardial inflammation. However, dilated cardiomyopathy patients with viral persistence do not respond favorably to immunosuppression.

MRI of acute myocarditis: a comprehensive approach based on various imaging sequences

STUDY OBJECTIVES

To explore the diagnostic performance of MRI for the diagnosis of acute myocarditis, using a comprehensive imaging approach.

DESIGN AND SETTINGS

Twenty patients with myocarditis and 7 age-matched and gender-matched control subjects underwent comprehensive MRI. Magnetic resonance (MR) examinations included axial T2-weighted sequences, precontrast and postcontrast ECG-gated T1-weighted sequences in axial and short heart axis, cine-MRI, and serial dynamic turbo fast low-angle shot (turboFLASH) acquisitions in the short axis following Gd injection for a period of 2 min. Precontrast and postcontrast images were postprocessed using subtraction. Two observers read all images qualitatively and quantitatively. Myocardial enhancement was compared between patients and control subjects.

PATIENTS

Myocardial involvement was focal in 6 patients examined within 1 week from clinical onset, and diffuse in the remaining 14 patients examined later.

RESULTS

Qualitatively, contrast-enhanced T1-weighted subtracted images had 100% sensitivity and specificity for myocardial involvement. Postcontrast T1-weighted images were able to discriminate the early phase (nodular enhancement) from the later phase of myocarditis (diffuse enhancement). Quantitatively, myocardial enhancement was 56% +/- 3.2% in patients, vs 29% +/- 3.1% in control subjects using T1-weighted MRI (p < 0.0001). Serial turboFLASH images displayed greater myocardial enhancement between 25 s and 120 s in patients than in control subjects (p < 0.0001); however, there was marked enhancement of skeletal muscles in both early and late stages of myocarditis compared to control subjects (p < 0.0001).

CONCLUSION

On the basis of subtracted cardiac-gated T1-weighted images and serial postinjection turboFLASH images, our study shows that myocarditis is largely, at least in the early stages, a focal process in the myocardium. It also provides evidence of transient skeletal muscle involvement, which may actually be useful for diagnosis.

Myocarditis in systemic lupus erythematosus

Although clinical manifestations of myocarditis in systemic lupus erythematosus are uncommon, noninvasive cardiac testing may detect subclinical cases. The pathogenesis of myocarditis in systemic lupus erythematosus has been ascribed to many factors, including autoimmunity, medications, and coexisting diseases. Lupus myocarditis merits urgent clinical attention because of the likely progression to arrhythmias, conduction disturbances and heart block, dilated cardiomyopathy, and heart failure. Endomyocardial biopsy can be used to identify the underlying inflammatory histopathology. Usual therapy includes high-dose corticosteroids, in addition to standard cardiac medications.

Myocarditis in patients with clinical presentation of myocardial infarction and normal coronary angiograms

OBJECTIVES

The aim of this study was to assess the diagnosis of myocarditis in patients presenting with acute myocardial infarction (MI) and normal coronary angiograms.

BACKGROUND

Most often in these patients, the etiologic diagnosis remains unclear once they are found to have normal coronary arteries. The diagnosis of myocarditis mimicking MI is clinically relevant, because numerous arguments suggest a relation between myocarditis and dilated cardiomyopathy. Myocardial indium-111 (111In)-antimyosin antibody (AMA)/rest thallium-201 (201Tl) imaging allows noninvasive detection of myocarditis.

METHODS

Forty-five patients admitted to three intensive care units for suspicion of acute MI, with normal coronary angiograms, were investigated. Indium-111-AMA planar images and then a dual-isotope rest AMA/201Tl tomographic study were performed. Six-month echocardiographic follow-up was obtained in 80% of the patients with initial left ventricular (LV) wall motion abnormalities.

RESULTS

In eight patients, AMA and 201Tl scintigraphy were negative. In two patients, a matched 201Tl defect and focal AMA uptake suggested acute MI (due to prolonged vasospasm or spontaneously reperfused coronary occlusion). In 17 patients, diffuse AMA uptake over the whole LV suggested diffuse myocarditis. In 18 patients, focal AMA uptake with a normal 201Tl scan suggested diffuse but heterogeneous, or focal myocarditis. Complete functional recovery was observed in 81% of the patients with a pattern of myocarditis.

CONCLUSIONS

Among 45 patients presenting with acute MI and normal coronary angiograms, 38% had diffuse myocarditis and 40% had a scintigraphic pattern of heterogeneous or focal myocarditis. Short-term follow-up showed complete LV functional recovery in 81% of these patients.

Giant cell myocarditis: most fatal of autoimmune diseases

OBJECTIVE

To increase awareness of giant cell myocarditis (GCM), its pathogenesis, and treatment.

METHODS

Review of relevant publications from the English-language literature.

RESULTS

GCM is a rare, frequently fatal inflammatory disorder of cardiac muscle of unknown origin, characterized by widespread degeneration and necrosis of myocardial fibers.Congestive heart failure and ventricular tachycardia are common clinical manifestations. GCM occurs primarily in previously healthy adults, although it is frequently associated with various systemic diseases, primarily of autoimmune causes. The inflammatory infiltrate is characterized by the presence of multinucleated giant cells and is distinct from cardiac sarcoidosis. Animal models of GCM are similar to models of other autoimmune disorders such as rheumatoid arthritis. The prognosis, which is poor despite partial responsiveness to immunosuppressive medications, is improved with cardiac transplantation.

CONCLUSIONS

The clinical and immunopathogenetic similarities with classical rheumatologic diseases, the differential diagnosis with sarcoidosis and other inflammatory conditions, and the use of standard immunosuppressive medications make GCM a disease process that should be added to the rheumatologist's expertise.