By including immunohistochemical parameters the WHF Task Force for the Definition of Acute and Chronic Myocarditis expanded the light microscopical Dallas criteria of myocarditis. The rapid development of new molecular biological techniques such as polymerase chain reaction (PCR) and in-situ hybridization has improved our understanding of the underlying etiological and pathophysiological mechanisms in inflammatory heart disease. Treatment of dilated cardiomyopathy with inflammation is still controversial, however. The American Myocarditis Treatment Trial could not demonstrate a significant difference in the improvement of ejection fraction between patients with active myocarditis in the cyclosporine/prednisolone treated group when compared to placebo. In the European Study of Epidemiology and Treatment of Inflammatory Heart Disease (ESETCID) patients with acute or chronic myocarditis are treated specifically according to the etiology of the disease. Patients are screened not only for infiltrating cells, but also for the presence of persisting viral genome (enterovirus, cytomegalovirus and adenovirus). By investigating endomyocardial biopsies of 3,055 patients ongoing inflammatory processes in the heart could be found in 17.2%. Only 182 showed a reduced ejection fraction below 45% fulfilling the entrance criteria for the ESETCID trial. These data imply that in symptomatic patients inflammatory heart muscle disease has to be considered regardless of left ventricular function and that endomyocardial biopsy can be an important tool for diagnosis. Virus could be detected in 11.8% (enterovirus 2.2%, cytomegalovirus 5.4%, adenovirus 4.2%). These first epidemiological results of this prospective randomized study demonstrate that viral persistence may contribute to the pathogenesis of inflammatory heart muscle disease, and that in chronic myocarditis viral persistence occurs in a smaller percentage of patients compared to previously published studies which were performed on highly selected patients.
Cardiomyopathies are heart muscle diseases, which have been defined by their central hemodynamics and macropathology and divided in five major forms: dilated (DCM), hypertrophic (HCM), restrictive (RCM), right ventricular (RVCM), and nonclassifiable cardiomyopathies (NCCM). Furthermore, the most recent WHO/WHF definition also comprises, among the specific cardiomyopathies, inflammatory cardiomyopathy as a distinct entity, defined as myocarditis in association with cardiac dysfunction. Idiopathic, autoimmune, and infectious forms of inflammatory cardiomyopathy were recognized. Viral cardiomyopathy has been defined as viral persistence in a dilated heart. It may be accompanied by myocardial inflammation and then termed inflammatory viral cardiomyopathy (or viral myocarditis with cardiomegaly). If no inflammation is observed in the biopsy of a dilated heart (< 14 lymphocytes and macrophages/mm(2)), the term viral cardiomyopathy or viral persistence in DCM should be applied according to the WHF Task Force recommendations. Within the German heart failure net it is the authors' working hypothesis, that DCM shares genetic risk factors with other diseases of presumed autoimmune etiology and, therefore, the same multiple genes in combination with environmental factors lead to numerous different autoimmune diseases including DCM. Therefore, the authors' primary goal is to acquire epidemiologic data of patients with DCM regarding an infectious and inflammatory etiology of the disease. Circumstantial evidence points to a major role of viral myocarditis in the etiology of DCM. The common presence of viral genetic material in the myocardium of patients with DCM provides the most compelling evidence, but proof of causality is still lacking. In addition, autoimmune reactions have been described in many studies, indicating them as an important etiologic factor. Nevertheless, data on the proportion of patients, in whom both mechanisms play a role are still missing.A pivotal role for autoimmunity in a substantial proportion of patients with DCM is supported by the presence of organ-specific autoantibodies, inflammatory infiltrates and pro-inflammatory cytotoxic cytokines. Furthermore, familial occurrence of DCM has been described in about 20-30% of cases, with the presence of autoantibodies and abnormal cytokine profiles in first-degree relatives with asymptomatic left ventricular enlargement. This suggests the involvement of a disrupted humoral and cellular immunity early in the development of the disease. A similar pattern of humoral and cellular immune dysregulation has been described in other autoimmune diseases. There is considerable evidence that genetic factors play an important role in the pathogenesis of DCM, either as contributors to the susceptibility to environmental factors or as determinants of functional and structural changes that characterize the phenotypic expression of the disease.Yet, it is not known whether the susceptibility to immunologically mediated myocardial damage reflects the presence of genetic risk fa...
Dilated cardiomyopathy (DCM) is a structural heart disease with strong genetic background. Monogenic forms of DCM are observed in families with mutations located mostly in genes encoding structural and sarcomeric proteins. However, strong evidence suggests that genetic factors also affect the susceptibility to idiopathic DCM. To identify risk alleles for non-familial forms of DCM, we carried out a case-control association study, genotyping 664 DCM cases and 1,874 population-based healthy controls from Germany using a 50K human cardiovascular disease bead chip covering more than 2,000 genes pre-selected for cardiovascular relevance. After quality control, 30,920 single nucleotide polymorphisms (SNP) were tested for association with the disease by logistic regression adjusted for gender, and results were genomic-control corrected. The analysis revealed a significant association between a SNP in HSPB7 gene (rs1739843, minor allele frequency 39%) and idiopathic DCM (p = 1.06×10−6, OR = 0.67 [95% CI 0.57–0.79] for the minor allele T). Three more SNPs showed p < 2.21×10−5. De novo genotyping of these four SNPs was done in three independent case-control studies of idiopathic DCM. Association between SNP rs1739843 and DCM was significant in all replication samples: Germany (n = 564, n = 981 controls, p = 2.07×10−3, OR = 0.79 [95% CI 0.67–0.92]), France 1 (n = 433 cases, n = 395 controls, p = 3.73×10−3, OR = 0.74 [95% CI 0.60–0.91]), and France 2 (n = 249 cases, n = 380 controls, p = 2.26×10−4, OR = 0.63 [95% CI 0.50–0.81]). The combined analysis of all four studies including a total of n = 1,910 cases and n = 3,630 controls showed highly significant evidence for association between rs1739843 and idiopathic DCM (p = 5.28×10−13, OR = 0.72 [95% CI 0.65–0.78]). None of the other three SNPs showed significant results in the replication stage.This finding of the HSPB7 gene from a genetic search for idiopathic DCM using a large SNP panel underscores the influence of common polymorphisms on DCM susceptibility.
The familial form of dilated cardiomyopathy (DCM) occurs in about 20%-50% of DCM cases. It is a heterogeneous genetic disease: mutations in more than 20 different genes have been shown to cause familial DCM. LMNA, encoding the nuclear membrane protein lamin A/C, is one of the most important disease gene for that disease. Therefore, we analyzed the LMNA gene in a large cohort of 73 patients with familial DCM. Clinical examination (ECG, echocardiography, and catheterization) was followed by genetic characterization of LMNA by direct sequencing. We detected five heterozygous missense mutations (prevalence 7%) in five different families characterized by severe DCM and heart failure with conduction system disease necessitating pacemaker implantation and heart transplantation. Four of these variants clustered in the protein domain coil 1B, which is important for lamin B interaction and lamin A/C dimerization. Although we identified two novel mutations (E203V, K219T) besides three known ones (E161K, R190Q, R644C), it was remarkable that four mutations represent LMNA hot spots. DCM patients with LMNA mutations show a notable homogenous severe phenotype as we could confirm in our study. Testing LMNA in such families seems to be recommended because genotype information in an individual could definitely be useful for the clinician.
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.
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