State of the Art Inflammatory Cardiomyopathy

Transcription

1 Hellenic J Cardiol 47: 54-65, 2006 State of the Art Inflammatory Cardiomyopathy KONSTANTINOS KARATOLIOS, SABINE PANKUWEIT, CHRISTIANE KISSELBACH, BERNHARD MAISCH Department of Internal Medicine and Cardiology, University Hospital of Giessen and Marburg, Philipps University Marburg, Germany Key words: Inflammatory cardiomyopathy, viral infection, polymerase chain reaction, immunohistochemistry. Manuscript received: December 28, 2005; Accepted: January 17, Address: Bernhard Maisch Department of Internal Medicine and Cardiology Philipps-University Marburg Baldingerst Marburg Germany maisch@med.unimarburg.de C ardiomyopathies are defined as diseases of the heart muscle (myocardium) associated with cardiac dysfunction. They are classified into five major forms by their central haemodynamics and macropathology: dilated, hypertrophic, restrictive, right ventricular, and non-classifiable cardiomyopathies. In 1995, a Task Force of the World Health Organisation and the International Society and Federation of Cardiology (ISFC, presently the World Heart Federation: WHF) introduced several changes in the definition and classification of heart muscle disease. 1 Previously the cardiomyopathies were defined as heart muscle diseases of unknown aetiology and were differentiated from the specific heart muscle diseases with known aetiology. 2 With the increasing understanding of their aetiopathogenesis, the difference between cardiomyopathies and specific heart muscle diseases has become indistinct. The term cardiomyopathy is now no longer reserved for the idiopathic forms but can be used interchangeably with the term heart muscle diseases. Right ventricular, valvular, hypertensive, ischaemic and inflammatory cardiomyopathy have been introduced as specific cardiomyopathies. This new WHO/ISFC definition also comprises inflammatory cardiomyopathy as a distinct entity among the specific heart muscle diseases. The inflammatory cardiomyopathy is defined by myocarditis in association with cardiac dysfunction. Myocarditis is an inflammatory disease of the heart muscle and is diagnosed by established histological, immunological and immunohistochemical criteria. Idiopathic, autoimmune, and infectious subtypes were recognised. 1 Viral cardiomyopathy is defined as viral persistence in a dilated heart. It may be accompanied by myocardial inflammation and is then termed inflammatory viral cardiomyopathy. The term viral cardiomyopathy or viral persistence in dilated cardiomyopathy should be applied if only viral RNA or DNA without inflammation is present. If both viral nucleid acid and inflammation are present, then the correct term is viral inflammatory cardiomyopathy. 3 If no viral or bacterial RNA or DNA is detected but inflammatory processes with preserved cardiac function are present, the correct term is autoreactive myocarditis. Both myocarditis and inflammatory cardiomyopathy reflect an inflammatory process in cardiac tissue. 4 Inflammation plays an important role in the pathogenesis of many common cardiovascular diseases. In most cases, the role of inflammation is a natural response to injury and an important mechanism for healing and tissue repair. However, the inflammatory reaction can be inadequate or overwhelming, leading to direct injury and severe host disease. Accumulating data show that inflammation is an important component in the pathogenesis of dilated cardiomyopathy. There is also growing evidence that 54 ñ HJC (Hellenic Journal of Cardiology)

2 Inflammatory Cardiomyopathy myocarditis is a precursor of dilated cardiomyopathy. Myocarditis can result in dilated cardiomyopathy with progression to heart failure in up to 30% of cases, where prognosis is poor, with a survival rate less than 40% after 10 years. 5 Post-mortem studies suggest that myocarditis is a major cause of sudden unexpected death in young adults less than 40 years of age, accounting for up to 20% in the population of those who die from cardiovascular causes. 6 In 1980, the introduction of the endomyocardial biopsy provided a method for assessing the presence of myocarditis and inflammation in the human heart. 7 However, early biopsy studies had highly variable results, with the incidence of myocarditis ranging from 0-80%. To resolve this problem arising from differences between the methods of diagnostic evaluation the Dallas criteria for the histological diagnosis of myocarditis by haematoxylin and eosin staining were introduced in Causes of myocarditis A large variety of infectious agents, systemic diseases, drugs and toxins have been associated with the development of myocarditis. 9,10 However, the aetiology of myocarditis often remains unknown. The spectrum of the infectious agents varies with the geographical region, the age of the patient, application of different therapeutic procedures and additional diseases. In general, viruses such as parvovirus B19, enteroviruses and adenoviruses represent the most commonly identified aetiological agents of viral cardiomyopathy. In addition, bacteria such as borrelia burgdorferi and chlamydia pneumoniae, protozoa and even fungi can also cause myocarditis (Table 1) In our area Parvo B19, sometimes with double infections including herpes viruses, is the leading aetiological agent. We regularly carry out a review of the most frequent cardiotropic viruses, including: Parvo B19, enteroviruses, CMV, EBV, influenza, herpes, in addition to chlamydia pneumoniae and borrelia burgdorferi. In our registry a rise of Parvo B19 to around 30% of the biopsied dilated cardiomyopathy and inflammatory dilated cardiomyopathy / myocarditis patients can be observed. An example of a positive polymerase chain reaction (PCR) is given in Figure 1. Viral infections are postulated to be the most common cause of myocarditis in Europe and North America. Initially, rising antibody titres against specific viruses in the serum of patients during acute myocarditis and reconvalescence were used to demonstrate aetiological relevance. 17 Recently, genomes of parvovirus B19, enterovirus, cytomegalovirus, influenza virus and hepatitis C virus have been identified in endomyocardial biopsies in patients with myocarditis and dilated cardiomyopathy using PCR However, the association of specific viruses with the pathogenesis of myocarditis remain controversial. In various investigations viral genomes were found in endomyocardial tissue in less then 40%, so that autoreactive forms still appear to be the most frequent subgroup. 19,20 Histology of inflammatory cardiomyopathy In 1999, the WHF/ISFC updated the conventional histological criteria for the diagnosis of inflammatory cardiomyopathy/myocarditis according to the Dallas classification by the introduction of immunohistochemical methods (Table 2). 20 Myocarditis was defined as a process characterised by an inflammatory Table 1. Infective agents of myocarditis. Viruses Bacteria Mycobacteria Fungi Protozoa Rickettsiae Chlamydiae Parasitic Enterovirus, rhinovirus, influenza A B, rubeola, mumps, HIV-1, hepatitis C virus, adenovirus, cytomegalovirus, Epstein-Barr virus, varicella-zoster, Parvovirus B19, human herpes 6 virus Staphylococcus, streptococcus, pneumococcus, meningococcus, gonococcus, salmonella, corynebacterium diphtheriae, haemophilus influenzae, mycoplasma pneumoniae, brucella Tuberculosis, avium intracellulare Aspergillus, candida, actinomyces, blastomyces, cryptococcus, histoplasma Toxoplasma gondii, trypanosoma cruzi Coxiella burnetti (Q fever), rickettsia rickettsii, Trachomatis, psittaci Trichinella spiralis (Hellenic Journal of Cardiology) HJC ñ 55

3 K. Karatolios et al Figure 1. Positive PCR for Parvo B 19 with a 600 basepair product in the Southern Blot in a 25 year old patient with myocarditis and congestive heart failure. infiltrate of the myocardium. The inflammatory infiltrate should be subclassified as lymphocytic, eosinophilic, neutrophilic, giant cell, granulomatous or mixed. The distribution of the infiltrate should be classified as focal, confluent or diffuse. In acute myocarditis necrosis and or degeneration of adjacent myocytes is required. In chronic myocarditis necrosis of myocytes is not obligatory. The WHF committee chose a minimum of 14 infiltrating leukocytes/mm 2 for the definition of myocarditis, preferably activated leukocytes (CD45ro) or T-lymphocytes (e.g. CD3)+. Up to 4 macrophages may be included in this total amount. In case of nests of leukocytes (>3 lymphocytes, preferably T-cells) located outside the lumen of a vessel, a focal inflammatory process (myocarditis) is diagnosed. If those foci are present, myocarditis can be diagnosed due to the nature of the infiltrate even when the critical number of 14 leukocytes is not reached. If the focal or diffused leukocytes are localised in fibrotic areas the process may be termed reparative. 20 The amount of fibrosis should also be classified as none (grade 0), mild (grade 1), moderate (grade 2) or severe (grade 3). The distribution of the fibrosis should be described as endocardial, replacement or interstitial. 20, 21 The following terminology has been suggested: First biopsy: 1. Acute (active) myocarditis: a clear-cut infiltrate (diffuse, focal or confluent) of 14 leukocytes (preferably activated T-cells) and macrophages/mm 2 (Figure 2). Quantification of the amount of the infiltrate should be made with immunohistochemical methods. Necrosis and degeneration are mandatory. Fibrosis may be absent or present and should be graded. 2. Chronic myocarditis: an infiltrate of 14 leukocytes and macrophages/mm 2 (diffuse, focal or confluent, preferably activated T-cells) quantitated by immunohistochemistry. Necrosis or degeneration are usually not evident. Fibrosis should be graded if present. 3. No myocarditis: no infiltrating cells or <14 leukocytes/mm 2. Subsequent biopsies: 1. Ongoing (persistent) myocarditis: Criteria as in 1 or 2 above (features of an acute or chronic myocarditis). Table 2. Histological criteria for the diagnosis of myocarditis according to the Dallas classification 8 and WHF. 20,21 Dallas terminology Histopathology WHF terminology Immunohistochemistry Infiltrate Myocytolysis Oedema First biopsy Active myocarditis Active myocarditis Corresponds to Dallas criteria Borderline + Chronic 14 lymphocytes/mm 2 myocarditis myocarditis/dcmi Second biopsy Ongoing myocarditis Ongoing myocarditis Corresponds to Dallas criteria Resolving/healing + Resolving or chronic 14 lymphocytes/mm 2 myocarditis myocarditis/dcmi Resolved Resolved myocarditis <14 lymphocytes/mm 2 myocarditis Immunohistochemistry aids in subclassification of infiltrating cells. DCMI inflammatory dilated cardiomyopathy. 56 ñ HJC (Hellenic Journal of Cardiology)

4 Inflammatory Cardiomyopathy Figure 2. Active myocarditis in the same patient as in Figure 1. Positive immunohistochemistry with Anti-CD 3 monoclonal antibody. 2. Resolving (healing) myocarditis: Criteria as in 1 or 2 above, but the immunologic processes are sparser than in the first biopsy. 3. Resolved (healed) myocarditis: Criteria corresponding to the Dallas classification. With the introduction of these quantitative criteria consensus could be reached in a large majority of cases of inflammatory cardiomyopathy. Pathophysiology of inflammatory cardiomyopathy/myocarditis Our understanding of the pathophysiology of myocarditis stems largely from murine studies With the application of cellular and molecular biological methods our understanding of myocarditis and its progression to dilated cardiomyopathy has increased remarkably. A clarification of the pathophysiology of induction and development of heart muscle damage and progression to dilated cardiomyopathy is important for diagnosis and therapy of the disease. Myocarditis is a continuum of three distinct disease processes, one evolving into the other with transitional periods of overlapping. Pathogenesis, diagnosis and management differ for each of the three processes. Precise knowledge of the point to which the patient s myocarditis has evolved in this triphasic continuum is essential for diagnostic and therapeutic strategies. In the majority of cases of myocarditis, except in countries in which Chagas disease or diphtheria is common, viral infection triggers the triphasic cascade, which may progress to an autoimmune phase after the initial infection and then finally progress to dilated cardiomyopa- thy. However, other forms of injury may also trigger the triphasic cascade, e.g. systemic diseases, chemicals and toxins. 26,27 In the first phase (initial myocardial injury by viral infection) an initial insult to the myocardium occurs. During phase I overt congestive heart failure does not occur in most cases and the initial injury may go unnoticed, unless fulminant myocarditis arises. In the second phase an autoimmune myocardial injury occurs, triggered by the initial injury despite elimination of the virus. Congestive heart failure often develops in this phase. In the third phase the typical clinical picture of dilated cardiomyopathy develops independently after the other two processes (infection and autoimmunity) have abated. Phase I: Initial myocardial injury The first phase is believed to be induced by infections (most commonly viral) in the majority of cases. During this phase in most patients severe heart failure does not occur and the initial myocardial injury may go unnoticed. Only in a few cases fulminant myocarditis arises, induced by direct myocytolysis of the normally replicating virus in the absence of a specific immune response. 28 Complete recovery from the disease in this phase depends on an effective immune response in the absence of subsequent autoimmune processes or viral persistence. In addition, the effectiveness of the immune response regulates the severity of virus-induced damage to the heart. 29 The factors responsible for clearance of the infectious agent on the one hand and the myocardial damage on the other are, first of all, cytotoxic T- lymphocytes (CD4+ and/or CD8+). Second, lymphocyte-derived perforins and serin esterases may be responsible for inducing apoptosis. Third, the different cytokines play a role in the initial myocardial injury. Recent evidence suggests that both B- and T-cells, natural killer and dendritic cells are involved in the production of polarising cytokines Inactivation of T-cells and associated cytokines after clearance of the infectious agent is necessary for complete recovery from the disease. Molecular mimicry, production of cross-reacting antibodies, or further activation of virally induced killer T-cells may give rise to the extension of myocarditis into the second phase of autoimmune myocardial injury. 26,27,30,31 Phase II: Autoimmune myocardial injury The immune system (cellular and humoral), normally (Hellenic Journal of Cardiology) HJC ñ 57

5 K. Karatolios et al down regulates to a resting state once viral proliferation is controlled. However, if the immune response continues despite elimination of the virus, autoimmune disease may result, initiating the second phase of the disease. In fact, the secondary immune response probably plays a greater role in disease pathogenesis than the primary infection. 26 Important mechanisms of the cellular immune response which may trigger pathogenic heart-specific autoreactivity are: 1. Activation by a foreign antigen: Processing of a foreign antigen might result in the presentation of an epitope highly homologous to cardiac myosin and other myocardial proteins. This leads to activation of crossreactive T-cells. 31,33 2. Increased presentation of self peptides: Viral infection and necrosis of myocytes may lead to the release of intracellular antigens, extracellular concentrations of which are normally very low. Release of these proteins in large quantities increases the threshold necessary for an immune response, resulting in activation of self-reacting T-cells. 31,33 3. Presentation of cryptic self-peptides: In addition, altered processing of intracellular localised proteins might occur, resulting in activation of self-reactive T- cells. This mechanism may then propagate an immune response to a cardiac antigen in the absence of further infectious triggers. 31,33 The role of the humoral immune response includes, first, the activation of cross-reactive antibodies, which alone are known to induce autoimmune inflammatory heart disease in animals. 34 Auto-antibodies belong to the effector mechanisms of the immune system responsible for tissue damage in various autoimmune disorders. These auto-antibodies are produced as a result of failure or breakdown of the mechanisms normally responsible for maintaining self-tolerance. Patients with myocarditis display serum antibodies to a number of cardiac antigens (Table 3). 35,36 Occurrence of these antibodies in sera of patients correlates with the extent of inflammation in the myocardium. Antibodies induce cytotoxicity in vitro, with or without complement, and binding of antibodies is inhibited by absorption with viral proteins indicating crossreactivity. 37 However, it is now widely accepted that the majority of antibodies directed against cardiac antigens found in the serum of patients with inflammatory cardiomyopathy do not play a major pathogenetic role but are indicative of damage to cardiac tissue and show a tendency to autoimmune disease. 38 In patients with inflammatory dilated cardiomyopathy, immune complexes have been found more frequently than in healthy individuals and in patients with dilated cardiomyopathy without inflammation. 39 These circulating immune complexes consisted of IgG, IgM, C3 and C4; in myocarditis IgM predominated. 30 Up to now, the nature of the soluble antigen (foreign or self?) has not been determined. However, immune complex deposition does not seem to play a major role in the pathogenesis of dilated cardiomyopathy. In this phase, the importance of latent or persistent virus in the pathogenesis of the disease is uncertain, but considerable. A low level or intermittent replication of persistent or latent viruses may induce chronic, direct immune or autoimmune injury to the myocardium. 27,31 Ongoing viral persistence is associated with a much worse outcome for the patient (need for heart transplantation or early sudden cardiac death). 26,40 Phase III: Dilated cardiomyopathy In phase III, after both the infectious and autoimmune processes have abated, the disease shows the characteristics of idiopathic dilated cardiomyopathy. The diagnosis is made by echocardiography, when other causes of dilatation are excluded (e.g. coronary artery disease). The therapy in this stage aims at prevention and reversal of adverse remodelling. 31 Separation of the three phases is not always possible. The three phases may overlap one another chronologically. Furthermore, phases I and II can recur after the triphasic cascade has progressed to dilated cardiomyopathy, resulting in multiple cycles of disease occurring simultaneously. 27 Diagnosis The clinical characteristics of myocarditis vary. The patients may remain asymptomatic and have electrocardiographic abnormalities. Other patients may show signs and symptoms of chronic heart failure and ventricular dilatation. Some patients may present with fulminant heart failure and severe left ventricular dysfunction, with or without cardiac dilatation. Unfortunately, myocarditis can also result in sudden unexpected death. In fact, myocarditis is the major cause of sudden unexpected death in patients less than 40 years of age. 6 Mason et al found that 60% of patients with myocarditis have antecedent flu-like symptoms. We have to bear in mind that the patients can present with a clinical syndrome mimicking that of an acute myocardial infarction with chest pain, ECG and laboratory find- 58 ñ HJC (Hellenic Journal of Cardiology)

6 Inflammatory Cardiomyopathy Table 3. Compilation of antibodies to cardiac antigen and their possible cross-reactivity and pathomechanism. Antigen Antibody Cross-reactivity with Pathomechanism Author (Reference) Actin Anti-actin Unknown Unknown Maisch et al. Ach receptor Anti-Ach Unknown Bradycardia Goin et al. AH Anti-AH Unknown Impairment of energy Pankuweit et al. metabolism PK Anti-PK DLD Anti-DLD CK Anti-CK ANT Anti-ANT Enterovirus Impairment of energy Schulze and metabolism Schultheiss b1-receptor Anti-b1 Enterovirus Positive chronotropic Wallukat et al. b1-receptor Anti-b1 Negative inotropic 1 Limas et al. Ca 2+ channel Anti-Ca 2+ ANT Enterovirus Unknown Schulze et al. Carnitin Anti-carnitin Unknown Otto et al. Conduction system Anti-sinus Unknown Conduction defect Maisch et al. Anti-AV node Anti-Purkinje Desmin Anti-desmin Unknown Maisch et al. Obermayer et al. Hsp60, hsp70, Anti-hsp60, Multiple Unknown Portig et al. vimentin Anti-hsp70, Anti-vimentin Laminin Anti-laminin Unknown Maisch et al. Mitochondria/microsomes AMA Multiple Inhibition of sarcosin Klein et al. dehydrogenase Pohlner et al. Myolemma AMLA Enterovirus Lytic Maisch et al. Myosin Anti-myosin Negative inotropic Maisch Myosin Anti-myosin Enterovirus Negative inotropic Caforio et al. NADD Anti-NADD Unknown Impairment of energy Pohlner et al. metabolism UCR Anti-UCR Nuclear antigen ANA Unknown Immune complex-mediated Naparstek and Poltz degranulation of neutrophils, AV-block ENA ENA ANCA Anti-SSA Anti-SSB Sarcolemma ASA Enterovirus 2 Lytic Maisch et al. SR-Ca-ATPase Metabolic interactions Khaw et al. From reference 21. Used with permission. 1 Hypothetical. 2 Experimentally proven. Ach acetylecholine; AH aconitate hydratase; AMA antimitochondrial antibody; AMLA antimyolemmal antibody; ANA antinuclear antigen; ANCA antineutrophil cytoplasmic antigen; ANT adenine nucleotide translocator; ASA antisarcolemmal antibody; CK creatine kinase; DLD dihydrolipoamide dehydrogenase; hsp heat-shock protein; NADD nicotinamideadenine dinucleotide dehydrogenase; PK pyruvate kinase; SR-Ca-ATPase sarcoplasmatic reticulum calcium ATPase; UCR ubiquinol-cytochrome-c reductase. ings of myocardial injury. The subsequent angiography shows normal coronary arteries. This large spectrum of clinical forms depends on several factors, such as genetic determinants of the infective agent, the genetics, age, gender and immunocompetence of the host. 10 To date, with the development of various new diagnostic methods, early and definite diagnosis of dilated inflammatory or infectious cardiomyopathy depends first on the detection of inflammatory infiltrates in the endomyocardial biopsies, according to the WHO/ ISFC and the Dallas criteria, using immunohistochemi- (Hellenic Journal of Cardiology) HJC ñ 59

7 K. Karatolios et al stry. 1,8,20 Molecular techniques such as PCR, gene sequencing and real time PCR, often applied on the same endomyocardial specimen, are essential for the rapid, specific and sensitive identification of the infective agents and discrimination between viral and autoimmune myocarditis. PCR investigation should include the following cardiotropic viruses: enterovirus, Epstein Barr virus, Parvo B19 virus, adenovirus, cytomegalovirus, human herpes virus 6, hepatitis C virus, and influenza viruses A and B. 37 The advantages of PCR analysis for definitive diagnosis of viral inflammatory cardiomyopathy can be summarised as follows: 1) rapid detection of specific microbial nucleid acid sequences; 2) detection of agents that are difficult to cultivate or cannot be cultivated; 3) detection of latent or active infections; 4) strain typing; and 5) detection of virulence and antimicrobial determinants. 41 The correct application of these methods may allow us to obtain information on epidemiology, risk stratification in a given patient and a more appropriate treatment. The role of endomyocardial biopsy Endomyocardial biopsy is the gold standard for the final diagnosis of myocarditis. The major limitation of endomyocardial biopsy remains the low sensitivity due to sampling error, particularly in the presence of focal disease. The size and number of the biopsy specimens, as well as the processing of the specimens, influence the sensitivity of endomyocardial biopsy in the detection of myocarditis. The number of biopsy samples directly increases the likelihood of detecting foci of myocarditis. 42,43 Furthermore, serial sectioning and multiple level examination of endomyocardial biopsies increase the sensitivity of endomyocardial biopsy in the evaluation of myocarditis, facilitating the diagnosis of focal myocarditis. 41,44 Some authors have demonstrated that biventricular endomyocardial biopsy, obtaining samples from multiple areas of the left and right ventricles, may increase the sensitivity in detection of myocarditis. 45 The high morbidity and mortality of myocarditis/inflammatory cardiomyopathy calls for a precise aetiological diagnosis, which is essential for the optimal treatment of the patient. Aetiological diagnosis of myocarditis can only be achieved with endomyocardial biopsy and subsequent molecular investigation of the biopsy samples. Echocardiographic findings in myocarditis may provide indirect evidence of inflammation by segmen- tal wall motion abnormality and associated pericardial effusion. 71 Magnetic resonance tomography may also be useful for the non-invasive localisation and assessment of the extent of inflammation in patients with myocarditis. Late enhancement may be a sign of interstitial oedema, as is the demonstration of increased pericardial fluid. However, additional studies are required to confirm the usefulness of the procedure. Treatment The design of the appropriate therapy for myocarditis is challenging because of the overlap of the pathophysiological stages of the disease. Appropriate therapy requires knowledge of the phase of the disease at the time therapy is applied. Such an evaluation requires immunohistochemical and molecular biological investigations of endomyocardial biopsies in parallel. 37 Phase-specific therapy is important because the appropriate therapy for one stage (e.g. immunosuppression in phase II) may worsen rather than improve myocarditis if administered at another stage (e.g. during active infection in phase I) (Figure 3). Phase I: Viral infection and replication Therapy for the first viral or bacterial induced phase requires an effective antiviral or antibacterial treatment, especially as viral infection represents an independent unfavourable prognostic factor in patients. 11,46 Kühl et al 68 investigated the effects of antiviral IFN- therapy in patients with myocardial virus persistence, with respect to the safety of the treatment regimen and virus clearance. They included 22 virus-positive patients with a long history of persistent or progressive left ventricular dysfunction despite medication with ACE inhibitors, -blockers, glycosides and diuretics. They found that a 6-month IFN- treatment was associated with myocardial virus clearance in all IFN- treated patients. Virus clearance was associated with haemodynamic improvement in these patients. Intravenous immunoglobulins have been more often used in the treatment of inflammatory dilated cardiomyopathy. It has been shown that immunoglobulins have both an antimicrobial, that is antiviral, and an anti-inflammatory effect. They prevent the formation of proinflammatory cytokines and downregulate their production, and supposedly reduce oxidative stress. 47 Thus, the use of intravenous immunoglobulin 60 ñ HJC (Hellenic Journal of Cardiology)

8 Inflammatory Cardiomyopathy may be a therapeutic option in all phases of myocarditis, since it has been shown that they have antiviral and anti-inflammatory effects. Table 4 gives an overview of all reports on high dose immunoglobulin treatment. Six of them are reported cases, one a series of cases, 56 one is a retrospective cohort study 56 and another is an uncontrolled trial. 49 Apart from the treatment of Coxsackie virus A19 with intravenous gamma-globulin by Wang et al, 55 clinical improvement was reported in all cases. It is of note that Drucker et al 56 compared the outcome and function of 21 children treated with intravenous gamma-globulin to 26 historic controls and found a significant improvement of cardiac function and a trend for improved survival. McNamara s uncontrolled trial 49 included ten adults, of whom nine showed considerable improvement of cardiac function and ejection fraction even after 12 months. However, one patient died from heart failure and ventricular arrhythmias. The only randomised controlled trial evaluating intravenous gammaglobulins in myocarditis was reported by McNamara et al. 48 Of the 62 adult patients enrolled, only ten demonstrated a cellular infiltrate compatible with active myocarditis according to the Dallas criteria, and three had borderline myocarditis in the respective endomyocardial biopsies. No assessment of viral aetiology was done. Thus the histological entrance criteria varied considerably and most importantly the aetiopathogenesis was unclear. Not unexpectedly, due to the incoherent group of patients with different possible aetiologies, there was no significant difference in event-free survival, nor a significant difference in the improvement of left ventricular ejection fraction for treated cases and controls at six and 12 months. These data are in conflict with an earlier non-randomised, uncontrolled trial by the same authors, 49 which showed some benefit. We would thus advocate a randomised-placebo controlled trial based on the viral aetiology or autoreactive pathology in patients with inflammatory cardiomyopathy. In biopsy-proven cytomegalovirus myocarditis, so far one controlled trial has demonstrated the eradication of inflammation and of the virus. 57 The trial enrolled 35 patients of whom 18 received intravenous cytomegalovirus hyperimmunoglobulin. The control group consisted of 17 patients with cytomegalovirus myocarditis who did not receive the treatment. Comparing the two groups, the effect of cytomegalovirus hyperimmunoglobulin treatment was clear (p<0.05 for Figure 3. Recommendation for a rational diagnostic pathway and treatment algorithm in the Marburg University Hospital for a patient admitted with suspected myocarditis (modified from reference 21, used with permission). (Hellenic Journal of Cardiology) HJC ñ 61

9 K. Karatolios et al Table 4. Trials and reports on intravenous immunoglobulins in suspected myocarditis. Authors Design n Histology Viral PCR IvIG dose Outcome McNamara et al, Randomised, 62 Only 10 active Not done 2 g/kg No improvement vs controlled trial and 3 borderline single shot controls myocarditis Drucker et al, Retrospective, cohort 46 children Only partly Not done 2 g/kg Pos. trend in mortality, study, historical cohort myocarditis single dose reduction in LVEDD McNamara et al, Case series 10 adults Only partly Not done 2 g/kg over Improvement of EF done, few 2-4 days after 12 months myocarditis Kishimoto et al, Case report 9 adults 4 myocarditis Not done 1-2 g/kg Improvement of NYHA, only over 2 days EF and FS Alter et al, Case report 1 Myocarditis Varicella 2 g/kg over Normalisation 2 days Takeda et al, Case report 1 Borderline EBV 2 g/kg over Improvement myocarditis 2 days Nigro et al, Case report 1 child Myocarditis Parvo B19 2 g/kg over Improvement, PCR days negative Tsai et al, Case report 1 child Not done Mycoplasma 2 g/kg over Improvement pneumoniae 2 days (serology) Shioji et al, Case report 1 adult Fulminant Not done, 2 g/kg over Improvement myocarditis negative 2 days serology Tedeschi et al, Case report 1 adult Not done Not done, 2 g/kg over Improvement negative 5 days serology Wang et al, Case report 1 child Fulminant Coxsackie A16 1 g/kg for Patient died myocarditis 2 days From reference 59, used with permission. EBV Epstein-Barr virus; EF ejection fraction; FS fractional shortening; IvIG intravenous immunoglobulin; LVEDD left ventricular end-diastolic diameter; NYHA New York Heart Association class; PCR polymerase chain reaction. cytomegalovirus-elimination and eradication of inflammation), which is in accordance with case reports. 58 In summary, whereas in cytomegalovirus myocarditis immunoglobulin data are promising, in merely suspected but unproven viral myocarditis the data are conflicting. A trial taking into account the different aetiologies (different viruses assessed separately versus non-viral/autoreactive versus placebo) would add important new information. In the Marburg Registry data support a positive effect of moderate-dose intravenous immunoglobulins (IgG and IgM pentaglobin) in adenovirus positive myocarditis for clinical improvement, eradication of both the inflammation and the virus. In Parvo B19 myocarditis the same registry indicates that clinical improvement can be noted, but only inflammation is successfully eliminated, whereas Parvo B19 persistence remains a problem in the majority of patients. 59 Phase II: Autoimmune myocardial injury Therapy for the second stage is an anti-inflammatory agent, which may be harmful if the virus persists in the myocardium. Immunosuppressive therapy has been demonstrated to be effective only when the autoimmune reaction is associated with dilated cardiomyopathy in the absence of viral genome. 60 The only published truly randomised and doubleblind immunosuppression treatment trial in patients with myocarditis diagnosed according to the Dallas 62 ñ HJC (Hellenic Journal of Cardiology)

10 Inflammatory Cardiomyopathy criteria was the Myocarditis Treatment Trial. 61,62 It showed neither a benefit nor increased mortality after six months of treatment with cyclosporine A and prednisone. It was underpowered and did not distinguish viral from non-viral disease. Frustaci et al, 67 in a retrospective analysis of patients with lymphocytic myocarditis, tried to define the virological and immunological profile of responders and non-responders to immunosuppressive therapy. They found that 85% of non-responders had viral genomes in the myocardium and no detectable cardiac antibodies in the serum. Conversely, only 14% of responders had viral particles in the myocardium, but 90% had cardiac autoantibodies. In conclusion, in patients with active lymphocytic myocarditis, the presence of detectable cardiac autoantibodies and the absence of viral genome in myocardial biopsy specimens represent a strong indication for immunosuppressive strategies. The European Study on the Epidemiology and Treatment of Cardiac Inflammatory Disease (ESET- CID) is a double-blind, randomised, placebo-controlled three-armed trial with prednisolone and azathioprine for autoreactive (virus-negative) inflammatory dilated cardiomyopathy (DCMi), interferon for enterovirus positive DCMi, high-dose immunoglobulin for cytomegalovirus and intermediate-dose for adenovirus and Parvo B19 virus DCMi. 63,64 It has now randomised more than 120 patients to the different arms. Its final results are still awaited. Patients not willing to be randomised in the trial were included in a registry followup, which shows improvement of haemodynamic parameters and elimination of the inflammation in the majority of patients. Since evidence is conflicting, treatment with immunosuppressives in aetiologically undefined myocarditis cannot be generally recommended. We should await further evaluation of double-blind, randomised clinical trials or at least controlled trials and registries. For the treatment of virus-negative (autoreactive) myocarditis it is recommended to await the results of ESET- CID. Some studies have demonstrated an important role for autoantibodies in the second and third phase of dilated cardiomyopathy and have also introduced a new therapeutic tool with the removal of immunoglobulins from the plasma of patients with dilated cardiomyopathy by immunoadsorption. 65,66 This new approach has been shown to improve ventricular function, 65 but the studies were not randomised and only poorly controlled. Phase III: Dilated cardiomyopathy In the absence of chronic, ongoing viral infection or recurrent autoimmune activity, the patients in stage III should be managed in the same way as those with idiopathic dilated cardiomyopathy and congestive heart failure. Further adverse ventricular remodelling may be prevented with -blockers, angiotensin-converting enzyme inhibitors and spironolactone. However, the facts that each phase may recur when one of the other two phases is well established, and that the virus may persist until phase III, causing further cardiac damage, underlines the need for monitoring for persistent viral infection and replication and recurrent autoimmunity. 26 Conclusion With the introduction of immunohistochemical and molecular biological methods an important improvement in the quantitative diagnosis of inflammatory heart diseases has been achieved. In addition, molecular techniques (e.g. PCR, gene sequencing) for viral genome detection have been introduced. Both methods make endomyocardial biopsy the gold standard for the definite diagnosis of the disease. Understanding the triphasic nature of myocarditis is the key to the treatment of the disease. However, overlap of the pathophysiological stages requires careful evaluation before the application of any specific therapy. Phase I is dominated by viral infection, phase II by the induction of autoimmune reactions, and phase III by the progression to cardiac dilatation. During phase I appropriate treatment includes eradication of the virus and amelioration of injury caused by the virus. During phase II immunosuppression is the most appropriate therapy. During phase III, dilated cardiomyopathy, though a result of viral and autoimmune injury, may then progress independently. References 1. Richardson P, McKenna W, Bristow M, et al: Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the Definition and Classification of Cardiomyopathies. Circulation 1996; 93: Report of the WHO/ISFC Task Force on the Definition and Classification of Cardiomyopathies. Br Heart J 1980; 44: Maisch B, Portig I, Ristic AD, et al: Definition of inflammatory cardiomyopathy myocarditis: on the way to consensus - a status report. Herz 2000; 25: Mattingly TW: Changing concepts of myocardial disease. JAMA 1965; 191: (Hellenic Journal of Cardiology) HJC ñ 63

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