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[Viral myocarditis and autoimmunity].

The pathogenesis of viral myocarditis has not been clarified yet especially in the subacute and chronic stages. Recent reports have shown that myocarditis may be caused by autoimmune reactions. Autoantigens and autoantibodies have recently been reported in myocarditis and cardiomyopathy, and most of them may be induced by the cross-reaction between virus and cardiac tissue, molecular mimicry, or by the destruction of immune tolerance. However it is not clear how autoimmune reactions affect viral myocarditis. We have reported that cytokines are increased in the blood of patients with myocarditis and cardiomyopathy. Many kinds of cytokines modulate viral myocarditis in different ways in murine models. Nitric oxide is also recognized as an important factor in viral myocarditis. We have reported that drugs for heart failure modulate cytokine production. Classifying drugs from this point of view may be helpful for developing new therapeutic strategy for patients with myocarditis and cardiomyopathy.

Animals↗

Dynamic Characteristic of Surface Phenotype of Peripheral Blood Lymphocytes in Myocarditis Patients.

A study of the expression of activated markers in peripheral blood lymphocytes makes it possible to carry out continuous monitoring of the immune system of a patient by means of a non-invasive method. This is of great importance for patients with acute myocarditis with immunopathological processes. However, there are very few papers in medical literature which are dedicated to this problem. Wherein, the number of lymphocyte markers being studied is, as a rule, very small. In order to characterize changes in the surface phenotype of lymphocytes during myocarditis, a study was conducted of the dynamics of surface lymphocyte markers in 45 patients with acute myocarditis during 12 weeks from the beginning of the illness. It is shown that a characteristic feature of myocarditis is a reduction in the number of T helpers (CD4(+)) and B lymphocytes (CD72(+)). However, the most marked changes were detected during evaluation of the expression of lymphocyte activation markers. An increase in the expression of all of the activation markers studied was noted two weeks after the beginning of myocarditis exacerbation. However, the earliest and most significant immunological feature indicating that the course of myocarditis has exacerbated is an increase in the portion of CD25(+) cells (the maximum increase is in the third week of the illness). The maximum of the increase of CD71(+) lymphocytes is in the fourth week of the illness, and an increase in the number of cells carrying the antigen HLA DR reaches a peak during the fifth-sixth week of myocarditis. The obtained results show that specific dynamics of expression of lymphocyte activation markers are typical for the immune status of patients with myocarditis. Exacerbation of the process is characterized by a substantial increase in the number of lymphocytes expressing CD25 antigen, later an increase in the number of CD71(+) lymphocytes is observed, and finally, an increase in the content of HLA DR(+) lymphocytes is typical for the inflammatory process developing in the myocardium.

Journal Article↗

Expression of vascular cell adhesion molecule-1 in murine hearts with acute myocarditis caused by coxsackievirus B3.

Cell-mediated autoimmunity has been strongly implicated in the pathogenesis of the myocardial cell damage involved in viral myocarditis. Using a murine model of acute myocarditis caused by Coxsackievirus B3 (CVB3), perforin-expressing killer cells have been shown to infiltrate the heart, and intercellular adhesion molecular-1 (ICAM-1) together with major histocompatibility complex (MHC) antigen was induced on myocardial cells in acute viral myocarditis. To clarify the immunological mechanisms in more detail, the expression of vascular cell adhesion molecular-1 (VCAM-1) has been examined in the heart of acute myocarditis and on cultured cardiac myocytes treated with interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha). The effects of in vivo antibody treatment to VCAM-1 on myocardial damage involved in acute myocarditis were also analysed. CVB3-induced myocarditis resulted in enhanced expression of VCAM-1 on myocardial cells. VCAM-1 expression was also induced on cultured cardiac myocytes by treatment with IFN-gamma and TNF-alpha. The in vivo antibody treatment to VCAM-1 decreased the myocardial damage to some extent, but the effects were not statistically significant. These data suggest that the expression of VCAM-1 on myocardial cells may play at least a partial role in the myocardial damage involved in acute viral myocarditis.

Acute Disease↗

Myocarditis: unresolved issues in diagnosis and treatment.

Myocarditis is an enigmatic disease. Lymphocytic myocarditis is most commonly viral in origin. Considerable evidence suggests that myocardial damage is due to an immune-mediated mechanism rather than to direct effects of the virus itself. The presentation is variable, ranging from a clinically inapparent or relatively benign illness to acute progressive heart failure and death. Although examination of the endomyocardial biopsy specimen is the "gold standard" for the diagnosis of myocarditis there are problems with this technique, relating particularly to sampling error and histologic interpretation. Considerable evidence, both animal and human, suggests that a link between viral myocarditis and dilated cardiomyopathy does exist. There is a rational basis for the use of immunosuppressive therapy in myocarditis. Although many favorable responses have been reported with the use of these agents, the results of more definitive studies are awaited to determine the role of immunosuppressive therapy in myocarditis more clearly. Recommendations for the practical management of patients with myocarditis are made. Whenever possible, patients with this diagnosis should be entered into the ongoing NIH trial.

Animals↗

Quantitative texture analysis in echocardiography: application to the diagnosis of myocarditis.

Altered myocardial texture associated with inflammatory infiltration or fibrosis of the myocardium has already been described using qualitative and subjective analysis of two-dimensional echocardiograms. The aim of this work is to test whether quantitative analysis of regional image texture in two-dimensional echocardiograms would be an accurate method to identify myocarditis and myocardial fibrosis. A set of 20 two-dimensional studies with endomyocardial biopsy evaluation was examined in 13 patients. Biopsy-proven myocarditis was present in 8 studies; myocarditis and fibrosis in 4; fibrosis in 3; healing/healed myocarditis in 5. A control group of 8 normal subjects was also studied by echocardiography. After quantitative texture analysis of the first order, entropy appeared to consistently differentiate myocarditis from controls. Among second-order parameters, patients affected by myocarditis or fibrosis showed a decreased entropy and higher angular second moment versus controls. We conclude that myocarditis and fibrosis induce similar image texture alterations in ultrasonic images, with increased spatial heterogeneity of the gray level distribution, which can be differentiated from normal structures with digital image analysis techniques.

Adult↗

Expression of tumour necrosis factor (TNF) ligand superfamily co-stimulatory molecules CD30L, CD27L, OX40L, and 4-1BBL in murine hearts with acute myocarditis caused by Coxsackievirus B3.

Antigen-specific T-cells infiltrate the heart and play an important role in the myocardial damage involved in acute myocarditis and dilated cardiomyopathy. To investigate the roles of the co-stimulatory molecules CD30/CD30L, CD27/CD27L, OX40/OX40L, and 4-1BB/4-1BBL, which belong to the tumor necrosis factor (TNF) receptor/ligand superfamily, in the development of acute viral myocarditis, the expression of these molecules was first analysed in the hearts of mice with acute myocarditis induced by Coxsackievirus B3 (CVB3) in vivo. Secondly, the induction of these molecules was evaluated on cultured cardiac myocytes treated with interferon (IFN)-gamma and the interleukin (IL)-6 production by cultured cardiac myocytes was analysed by stimulation with monoclonal antibodies (MAbs) against these molecules in vitro. Thirdly, the effects of in vivo administration of anti-CD30L, anti-CD27L, anti-OX40L, or anti-4-1BBL MAb on the development of acute viral myocarditis were examined. CVB3-induced myocarditis resulted in the induction of CD30L and 4-1BBL on the surface of cardiac myocytes, confirmed by treatment with IFN-gamma in vitro. CD27L and OX40L were constitutively expressed on cardiac myocytes in vivo and in vitro. Anti-CD30L and anti-4-1BBL MAbs stimulated IL-6 production by cardiac myocytes in vitro. Furthermore, in vivo anti-4-1BBL MAb treatment significantly decreased the myocardial inflammation, whereas the other MAbs did not. These findings suggest that TNF ligand superfamily co-stimulatory molecules, especially 4-1BBL, play an important role in the development of acute viral myocarditis and raise the possibility that immunotherapy with anti-4-1BBL MAb may be of benefit in acute viral myocarditis.

4-1BB Ligand↗

Chronic myocarditis induced by T cells reactive to a single cardiac myosin peptide: persistent inflammation, cardiac dilatation, myocardial scarring and continuous myocyte apoptosis.

Recent recognition that an autoimmune myocarditis may precede, and result in, dilated cardiomyopathy has focused attention on immune mechanisms of myocardial injury. In this paper, we describe a model of chronic autoimmune myocarditis in the Lewis rat. The production of myocarditis has been previously described by this group and in brief is accomplished by a single tail vein infusion of activated T cells specific for a 17-amino acid peptide from rat cardiac myosin. In this report, animals were followed for approximately 6 months post-T-cell infusion. Hearts from animals which received cardiac myosin specific T cells all showed extensive fibrosis associated with ongoing inflammation. Apoptosis, identified by TdT-mediated dUTP nick end labelling (TUNEL), was identified as a mode of myocyte death in hearts with acute and chronic myocarditis but not in age- and sex-matched controls. Immunohistochemistry was used to characterize the immune infiltrate and adhesion molecules in hearts with chronic myocarditis and these findings were compared to hearts with acute myocarditis. We propose that this rat model of chronic myocarditis mimics human disease, since inflammation results in ventricular dilatation and myocyte hypertrophy reminiscent of dilated cardiomyopathy. This model offers potential for further investigation of immune, functional and possible therapeutic aspects of autoimmune related cardiomyopathies.

Adoptive Transfer↗

Experimental rat model representing both acute and chronic heart failure related to autoimmune myocarditis.

The most important clinical manifestation of myocarditis is congestive heart failure. The precise mechanisms of heart failure during myocarditis have not been elucidated because no animal model that would permit in vivo study of hemodynamics in severe active myocarditis has been available. We monitored hemodynamics and left ventricular function in a rat model of experimental autoimmune myocarditis to determine if this model could be useful for the study of in vivo hemodynamics in severe active myocarditis. Lewis rats were immunized with human cardiac myosin suspended in complete Freund's adjuvant. Baseline hemodynamics were measured using an ultraminiature catheter pressure transducer via the right internal carotid artery, 4 weeks after immunization in one group of rats (acute phase) and 3 months after immunization in another group (chronic phase). Untreated rats served as the control group. Hemodynamic measurements were also obtained after infusion of dobutamine in the acute-phase and chronic-phase groups. The heart weight-to-body weight ratios were significantly higher in both the acute-phase group and the chronic-phase group compared with normal control rats. The baseline left ventricular systolic pressure was significantly lower in the chronic phase group than in the control group. Peak dP/dt and peak -dP/dt were significantly lower in both the acute-phase group and the chronic-phase group compared with the control group. Dobutamine significantly increased left ventricular systolic pressure, peak dP/dt, and peak -dP/dt in the chronic-phase group but caused only minor changes in hemodynamic variables in the acute-phase group. In vivo measurements of hemodynamic variables indicated the presence of left ventricular dysfunction in rats with experimental autoimmune myocarditis. This animal model may be useful for the study of both acute heart failure related to acute myocarditis and chronic heart failure due to diffuse myocardial fibrosis.

Acute Disease↗

Changes in perfusion and fatty acid metabolism of rat heart with autoimmune myocarditis.

To elucidate the change in perfusion and aerobic metabolism in myocarditis, tissue counting and dual tracer ex vivo autoradiography with Tl-201 and a free fatty acid analog, I-123- or I-125-labeled (p-iodophenyl)-methyl-pentadecanoic acid (BMIPP), were performed in rats with myocarditis induced by immunization with cardiac myosin. Inflammatory damage was classified histologically. At the acute stage (2-4 weeks after the antigen-injection), total heart uptakes of Tl and BMIPP and the ratio (BMIPP/Tl) were significantly reduced in myocarditis rats (N = 15) compared with the controls (N = 12). Myocardial distribution of Tl and BMIPP was not homogeneous. Relative uptake of Tl and BMIPP (N = 9, 128 regions) was gradually decreased with the extent of inflammation, and the regional BMIPP/Tl was smaller than the control. At the subacute stage (7 weeks after the antigen-injection), total Tl uptake in myocarditis rats (N = 5) recovered to the control level (N = 4), but that of BMIPP was still significantly lower than the control. BMIPP/Tl was still significantly lower in myocarditis. Myocardial distribution of Tl and BMIPP recovered to be more homogeneous. Relative uptake of Tl and BMIPP (N = 6, 78 regions) still gradually but significantly decreased with the extent of inflammation. Regional BMIPP/Tl was still depressed in myocarditis. These results indicate that myocardial perfusion and aerobic metabolism were discrepant and heterogeneously suppressed with severe inflammation during the acute stages, but the difference decreases with time. Examination with Tl-201 and BMIPP may provide information about the severity of myocarditis.

Animals↗

Cardiac troponin T: its role in the diagnosis of clinically suspected acute myocarditis and chronic dilated cardiomyopathy in children.

This study was conducted to assess the use of the serum cardiac troponin T (cTnT) level as a noninvasive indicator to differentiate acute myocarditis and chronic dilated cardiomyopathy in pediatric patients. Myocarditis and dilated cardiomyopathy are clinically difficult to differentiate. Endomyocardial biopsy proved to be quite useful. However, the nature of the procedure--invasiveness, time-consuming, and limited sensitivity--caused some concerns, especially in pediatric patients. Hence, we attempted to find an alternative method that could give a prompt diagnosis of acute myocarditis. Twenty cases with clinically suspected myocarditis or dilated cardiomyopathy and a control group of 21 cases with moderate left-to-right shunt and congestive heart failure were recruited. History, physical examination, electrocardiogram, chest roentgenogram, echocardiogram, cTnT, creatine kinase MB isoenzyme (CK-MB mass), and/or endomyocardial biopsy were compared. The gold standard used to diagnose myocarditis is endomyocardial biopsy (Dallas criteria) and/or recovery from cardiovascular problems within 6 months of follow-up. Ten patients were diagnosed as having myocarditis (group 1) and 10 with chronic dilated cardiomyopathy (group 2). The control group of 21 cases was designated as group 3. The median serum cTnT levels were 0.088 (0.04-3.11), 0.010 (0.010-0.990), and 0.010 (0.010-0.550) ng/ml in groups 1, 2, and 3, respectively. The mean CK-MB mass level for groups, 1, 2, and 3 were 18.35 (7.14-70.00), 4.80 (0.54-108.00), and 2.26 (0.95-7.06) ng/ml. The study showed that both the cTnT and CK-MB mass levels were significantly higher in group 1 than either group 2 or group 3. Histopathology was studied in 9 cases. In 2 of 5 cases and in all 4 cases in group 1 and group 2 histopathology was pathologically proved. Levels of cTnT and CK-MB were significantly higher for myocarditis than for dilated cardiomyopathy and left-to-right shunt with CHF. Further study is needed to assess the optimum cTnT level for differentiating both conditions.

Acute Disease↗

Treatment of inflammatory dilated cardiomyopathy and (peri)myocarditis with immunosuppression and i.v. immunoglobulins.

OBJECTIVES: Treatment objectives in inflammatory dilated cardiomyopathy (DCMi), myocarditis (M) and peri(myo)carditis are 1) the elimination of inflammatory cells from the myocardium and pericardium, 2) the elimination or (second best) mitigation of B-cell products such as antibodies and immuncomplexes directed against cardiac epitopes such as sarcolemmal, fibrillary and mitochondrial epitopes, and 3) the eradication of the causative viral or microbial agent, if present. ANTIPHLOGISTIC TREATMENT: A "non-specific" anti-inflammatory treatment in peri(myo)carditis can be carried out with antiphlogistics (NSAIDs preferably colchicine 1-3 mg/d) independent from the presence of the infective agent. In larger virus and bacteria negative effusions we recommend intrapericardial instillation of cristalloid triamcinolon (Volon A) at a dose of 500 mg/m(2), which should be left in place to have a sustained effect over at least 4 weeks. This will effectively prevent recurrences particularly when colchicine is added over a period of at least 3-6 months. Taking into account the 2004 ESC task force recommendations on the management of pericardial diseases the treatment recommendation for NSAIDs and colchicine can be classified as level of evidence A, indication class I, for intrapericardial triamcinolon instillation as level of evidence B, indication class IIa. IMMUNOSUPPRESSION: In (immuno)histologically validated autoreactive (virus negative) myocarditis and DCMi double-blind randomized trials are lacking to demonstrate the superiority of immunosuppression over conventional heart failure management. The only published randomized and double-blind immunosuppression treatment trial (American Myocarditis Treatment Trial) was underpowered and did not distinguish viral from non-viral disease. It showed neither benefit nor harm of a combination of cyclosporin and prednisone. A number of retrospective analyses of immunosuppression in myocarditis showed some benefit of surrogate parameters (ejection fraction, exercise tolerance) but improvement under conventional heart failure treatment cannot be ruled out completely as the main cause for amelioration. ESETCID (European Study on the Epidemiology and Treatment of Cardiac Inflammatory Disease) is a double-blind, randomized, placebo-controled three-armed trial with prednisolone and azathioprine for autoreactive (virus negative) DCMi, interferon alpha for enterovirus positive DCMi, high-dose immunoglobulin for cytomegalovirus and intermediate dose for adeno- and Parvo B19 DCMi. It has now randomized more than 120 patients to the different treatment arms. Its final result has still to be awaited.-Patients not willing to randomize in the trial were included in a registry follow-up, which shows improvement of hemodynamic parameters and elimination of the inflammation in the majority of patients. This is in concordance with several non-randomized trials. Since evidence is conflicting (level of evidence C, indication class IIb; if negative viral etiology is taken into consideration class IIa) treatment with immunosuppression cannot be generally recommended but should be further evaluated in doubleblind randomized clinical trials or at least in controlled trials and registries. This also applies to treatment with interferon for enteroviral or other viral infections in the heart. IMMUNOADSORPTION: : The elimination of anticardiac antibodies, which have been associated with DCMi, is a currently discussed concept, which is supported by published registry data and a few very small controlled investigations but not by a randomized double-blind trial with clinical endpoints of relevance. In some studies immunoglobulins have been substituted, so that an additional immunomodulatory effect has to be taken into account. The current proof of concept can be ranked level of evidence C, indication class IIa only. An even more challenging and still more attractive hypothesis is that cardiac inflammation caused by specific circulating beta-adrenoceptor antibodies can be eradicated with the elimination of the beta-receptor antibody thus healing dilated cardiomyopathy. Application of this approach can be ranked level of evidence C, indication class IIb at present only. Therefore these two pathophysiologically attractive concepts have to await further validation by a double-blind, randomized clinical endpoint trial. IMMUNOGLOBULIN TREATMENT: It has been shown that immunoglobulins have both an antiviral and an anti-inflammatory effect. They may suppress proinflammatory cytokines and reduce oxidative stress. HIGH-DOSE I.V. IMMUNOGLOBULINS (IVIG): In biopsy proven CMVmyocarditis a controlled trial demonstrated eradication of inflammation and of the virus (level of evidence B, indication class IIa), which is in accordance with registry data and case reports. In suspected myocarditis (not biopsy proven, no viral etiology established or excluded) conflicting data exist with respect to the improvement of surrogate markers such as the ejection fraction under high-dose immunoglobulins. More evidence can be weighted in favour of a positive treatment effect (level of evidence B, indication class IIb). Importantly there were no detrimental effects of the ivIG reported in these trials. One has to consider the high costs of this treatment, however. A trial taking into account the different etiologies (different viruses assessed separately vs. non-viral/autoreactive vs. placebo) is still lacking. MODERATE-DOSE I.V. IMMUNOGLOBULINS: Registry data support a positive effect of 20 g i.v. pentaglobin (IgG and IgM) in adenovirus positive myocarditis for clinical improvement, eradication of both the inflammation and the virus. In Parvo B19 myocarditis our own registry data indicate that clinical improvement can be noted, but only inflammation is successfully eliminated, whereas Parvo B19 persistence remains a problem in the majority of patients. In Parvo B19 associated DCMi therefore dose finding studies and randomized trials are needed.

Cardiomyopathy, Dilated↗

[Indication for myocardial biopsy in myocarditis and dilated cardiomyopathy].

This review may serve as a basis for evaluating publications on the topic "myocardial biopsy for myocarditis and dilated cardiomyopathy" in the clinical practice. The literature is particularly analyzed to answer the question, whether an endomyocardial catheter biopsy is indicated in patients with these myocardial disorders in the clinical routine besides its unequivocal scientific value. The judgment of the biopsy samples has been based on the classically histological and for years on the additional immunohistochemical and molecular biological-virological examination. The analysis of the literature data shows that outside scientific studies there is no indication to perform myocardial biopsy, or in other words, this procedure is not suitable for diagnosis, therapy, detection of early stages or prognostic evaluation in the disease spectrum "myocarditis, inflammatory heart disease, dilated cardiomyopathy". Reasons are the subjectivity in the judgment and interpretation of bioptic findings resulting in considerable interobserver variability, a missing standardization in biopsy performance, methods of examination and diagnostic criteria, the bioptic sampling error, missing therapeutic and prognostic consequences and potentially severe complications in performing myocardial biopsies. So far, the specificity of inflammatory changes in patients with dilated cardiomyopathy has not been proven in controlled blinded studies. The bioptic changes could be understood also as an unspecific inflammatory process in front of increasing pathophysiological evidence for myocardial inflammation in any form of heart failure. In addition, regarding the specific etiology of dilated cardiomyopathy, primarily a genetic, noninfectious or autoimmunologic origin plays an increasing role. The favorable clinical course and the very good prognosis of the acute, clinically diagnosed or supposed viral myocarditis should also be taken into account for the evaluation of myocardial biopsy. It should also be considered that the proof of causality between acute myocarditis and dilated cardiomyopathy is still lacking. Regarding the diagnosis "inflammatory cardiomyopathy" and multiple inflammatory subsets among patients with dilated cardiomyopathy or unclear regional contraction disorder, there is no adequate clinical validation of different diagnostic methods, criteria and interpretations so far. It is missleading to replace the well-established clinical diagnosis myocarditis by the bioptic diagnosis "inflammatory cardiomyopathy". However, endomyocardial catheter biopsy is clearly indicated in rare patients with fulminant myocarditis, giant-cell myocarditis and myocardial storage disease. Its probably underestimated role in sarcoid heart disease still needs to be clarified by systematic studies.

Acute Disease↗

99mTc-Hynic-annexin V imaging to evaluate inflammation and apoptosis in rats with autoimmune myocarditis.

Inflammation and cell death are two important components of myocarditis. We evaluated the distribution of inflammation and apoptotic cell death in rats with autoimmune myocarditis using two radiotracers - technetium-99m Hynic-annexin V ((99m)Tc-annexin) as a marker of apoptotic cell death and carbon-14 deoxyglucose ((14)C-DG) as a marker of inflammation - in comparison with histologic findings. Three, 7 and 14 weeks after immunization with porcine cardiac myosin (acute, subacute, and chronic phases, respectively) (99m)Tc-annexin and (14)C-DG were injected. The uptake in the total heart was determined as the percentage of injected dose per gram (% ID/g) by tissue counting. Dual-tracer autoradiography with (99m)Tc-annexin and (14)C-DG was performed. The distribution of each of these agents was compared with the results of hematoxylin and eosin staining to identify areas of inflammation, and TUNEL staining to identify areas of apoptosis. Total cardiac uptake of (99m)Tc-annexin in the acute phase of myocarditis was significantly higher than that in normal rats (1.28%+/-0.30% vs 0.46%+/-0.01%; P<0.0001); it then decreased in the subacute phase and reached normal levels (0.56%+/-0.08% vs 0.60%+/-0.08%; P=NS). Total cardiac uptake of (14)C-DG in the acute phase of myocarditis was significantly higher than that in normal rats (2.78%+/-0.95% vs 1.02%+/-0.25%; P<0.0001); it then decreased in the subacute phase, but still remained higher than in controls (2.06%+/-0.52% vs 1.37%+/-0.46%; P<0.05). Using autoradiography and staining of tissue specimens, it was found that most histologic inflammatory foci corresponded to areas of high (14)C-DG uptake; some also corresponded to areas of high (99m)Tc-annexin uptake in the acute phase of myocarditis. (99m)Tc-annexin localization was strongly correlated with the number of TUNEL-positive cells (P<0.0001, r=0.83), but the uptake of (14)C-DG showed no relationship with it. There is a marked difference in the distribution of inflammation and apoptotic cell death in the myocardium of animals with immune myocarditis. These changes are mirrored by the localization of (14)C-DG and (99m)Tc-annexin. Sites of inflammation and zones of apoptotic cell death change over the course of immune myocarditis.

Animals↗

A novel experimental model of giant cell myocarditis induced in rats by immunization with cardiac myosin fraction.

It is suspected that autoimmune disease processes are involved in the pathogenesis of a part of giant cell myocarditis. However, evidence for autoimmunity has rarely been demonstrated in clinical investigations. In this study, we have demonstrated a new animal model of autoimmune myocarditis characterized by the appearance of multinucleated giant cells. Lewis rats were immunized twice with human cardiac myosin fraction in complete Freund's adjuvant. Cardiac myosin fraction was prepared from the ventricular muscle of human hearts. Three weeks after the first immunization, acute and severe myocarditis was elicited in all rats. This myocarditis was characterized by massive pericardial effusion, enlargement of the heart, and gray discoloration of the cardiac muscle. Microscopically, there was marked cellular infiltration consisting of mononuclear cells, neutrophils, fibroblasts, and a considerable number of multinucleated giant cells. Extensive myocardial necrosis was also present. The heart weights increased from the third week to the fourth week and then gradually decreased. The titer of anti-myosin antibodies began to elevate from the second week and remained high until the sixth week. In the sixth week, inflammation became smoldering and the multinucleated giant cells disappeared. These findings indicate that the cardiac myosin fraction contains myocarditogenic antigen and that giant cell myocarditis can be induced by autoimmune involvement. To our knowledge, this is the first report of experimental giant cell myocarditis, which is closely similar to human giant cell myocarditis in its histology and clinical course.

Animals↗

Clinicopathologic characteristics of elderly patients with persistent ST segment elevation and inverted T waves: evidence of insidious or healed myocarditis?

OBJECTIVES: We sought to clarify the clinicopathologic characteristics of insidious or healed myocarditis in the elderly. BACKGROUND: Myocarditis is the cause of unexplained congestive heart failure and dilated cardiomyopathy. However, acute myocarditis of the Fiedler type is rare, and the incidence and implication of insidious or healed myocarditis in the elderly are not yet known. METHODS: In an autopsy study of 3,000 patients aged > or = 60 years, there were 12 (0.4%) with insidious or healed myocarditis, showing extensive and circumferential fibrosis and scattered lymphocytic infiltration of both ventricular walls without acute necrosis of the myocardial fibers. RESULTS: Unexplained congestive heart failure was found in seven cases. In all cases, electrocardiography had demonstrated upward elevation of the ST segment and inverted T waves for durations ranging from 1 month to 12.7 years (mean 5.7 years). Mean (+/- SD) heart weight was 338 +/- 81 g (range 220 to 470). In nine cases, fibrous lesions, which were scattered but extensive and circumferential, were located in the subepicardial and middle layers of the left ventricle. In the remaining three cases, the fibrous lesions were located predominantly in the subepicardial and middle layers, but the subendocardial layer was also locally involved. Fibrous lesions of the right ventricle were predominant in the subepicardial layer and involved the subendocardial layer in four cases. Scattered lymphocytic infiltration was found in the fibrous lesions. CONCLUSIONS: In more than half of the aged cases with insidious or healed myocarditis, unexplained congestive heart failure was also present. Fibrous lesions due to myocarditis were located predominantly in the subepicardial and middle layers and led to persistent upward elevation of the ST segment and inverted T waves.

Aged↗

Survival in biopsy-proven myocarditis: a long-term retrospective analysis of the histopathologic, clinical, and hemodynamic predictors.

OBJECTIVE: We hypothesized that histopathology predicts survival without cardiac transplantation in patients with biopsy-proven myocarditis. BACKGROUND: The role of endomyocardial biopsy in diagnosing myocarditis remains controversial. Histopathology has been integrated with clinical and hemodynamic features to predict prognosis. However, the influence of histopathology on survival > 5 years has not been explored. METHODS: We retrospectively identified 112 consecutive patients with histopathologic confirmation of myocarditis. We examined these patients' clinical presentation, hemodynamic assessment, hospital course, and treatment. We selected 14 variables that might influence survival without cardiac transplantation. RESULTS: A total of 62 (55%) of 112 patients had lymphocytic myocarditis; 88 (79%) and 63 (56%) were alive without cardiac transplantation at 1 and 5 years, respectively. Median follow-up was a mean 95.5 months and median 74.5 months. Among the 55 with complete data of the 14 candidate predictor variables, age, sex, and clinical presentation with congestive heart failure and ventricular (ventricular tachycardia or fibrillation) or atrial arrhythmias (atrial fibrillation or flutter) did not predict the study end point of death or need for transplantation. In univariate analysis, pulmonary capillary wedge pressure > or = 15 mm Hg significantly predicted the study end point. In multivariate analysis, pulmonary capillary wedge pressure > or = 15 mm Hg and histopathology of lymphocytic, granulomatous, or giant cell myocarditis each significantly predicted mortality or transplant (P = .047, P = .013, and P = .054, respectively) on cumulative survival without cardiac transplantation. CONCLUSIONS: Histopathology predicts long-term survival in patients with myocarditis. Clinical presentation, including presentation with congestive heart failure, ventricular tachycardia/ventricular fibrillation, or atrial fibrillation/atrial flutter, does not predict survival without transplantation. Endomyocardial biopsy can play a role in predicting transplant-free survival in patients with myocarditis.

Analysis of Variance↗

An in vivo model of autoimmune post-coxsackievirus B3 myocarditis in severe combined immunodeficiency mouse.

OBJECTIVE: Severe combined immunodeficiency (SCID) mice possess neither T nor B lymphocytes and are thus suitable recipients for adoptively transferred lymphocytes. Because autoimmune mechanisms may be involved in the pathogenesis of coxsackievirus B3 (CB3) myocarditis, we attempted to assess the in vitro cellular damage caused by antigen-sensitized lymphocytes and to determine whether splenic lymphocytes from BALB/c mice with chronic CB3 myocarditis could cause myocarditis into SCID mice. METHODS AND RESULTS: Cytotoxic cellular damage against non-myocytes and myocytes was demonstrated using 51Cr-release assay by lymphocytes cultured from myocarditis specimens or splenocytes from mice with chronic CB3 myocarditis. Severe T lymphocyte infiltration with myocardial necrosis was found in adoptively splenocyte-transferred SCID mice, but myocardial necrosis was not defected in wild-type mice by the same procedure. CONCLUSIONS: Autoimmune mechanisms might operate in mice with post-CB3 myocarditis and could be transferred in to SCID mice by the antigen-sensitized lymphocytes. An in vivo model of autoimmune post-viral myocarditis in SCID mouse was demonstrated.

Animals↗

Short-term prognostic value of initial serum levels of interleukin-10 in patients with acute myocarditis.

The disease course of acute myocarditis has a wide spectrum and the predictors of the prognosis in patients with acute myocarditis have not yet been established. In the pathogenesis of myocarditis, the cytokine environment is important. In this study, we examined the predictive values of serum levels of interleukin-10 (IL-10) and IL-12 in the short-term prognosis of patients with acute myocarditis. Twenty-four consecutive patients who had been diagnosed as having acute active myocarditis were analyzed and monitored for 2 months. The patients with myocarditis were divided into the survival group (n=16) and the non-survival group (n=8). Initial serum levels of IL-10 (P=0.0015) and IL-12 (P=0.012) in the non-survival group were significantly higher than those of the survival group, and there was a significant correlation between IL-10 and IL-12 levels (P<0.0001). The univariate analyses showed that increased serum levels of IL-10 (hazard ratio 1.041, P=0.0004) and IL-12 (hazard ratio 1.128, P=0.0346) were significant predictors of mortality. In the Kaplan-Meier analysis, high levels of IL-10 (>or=7.0 pg/ml) (P=0.0239) strongly predicted high mortality. In conclusion, the elevation in serum IL-10 levels at the initial phase appeared to predict poor short-term prognosis in patients with acute myocarditis.

Acute Disease↗