Anette Richter

Inflammatory Dilated Cardiomyopathy (DCMI)

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/mm2), 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 factors shared by other autoimmune diseases. Preliminary investigations suggest, that this is the case, because the frequency of autoimmune disorders other than DCM was higher in first-degree relatives of the subjects with DCM including juvenile diabetes, rheumatoid arthritis, thyroiditis, psoriasis, and asthma.The nature of the genetic risk is undetermined and probably involves genes in the major histocompatibility (MHC) locus as well as other susceptibility loci. Therefore, the authors started their investigation with the search for MHC class 2 DQ polymorphisms in the peripheral blood of patients with DCM in parallel to the search for new interesting susceptibility loci by the use of the microarray analysis regarding genes responsible for inflammatory and autoimmune diseases. By this approach a new insight in the familial clustering of other autoimmune diseases in patients with DCM and in genetic predisposition can be expected.ZusammenfassungKardiomyopathien werden nach der letzten Klassifikation der WHO/ISFC-(WHF-)Task Force nach ihren makropathologischen und hämodynamischen Kriterien in fünf Formen eingeteilt: dilatative (DCM), hypertrophische (HCM), restriktive (RCM), rechtsventrikuläre (RVCM) und nicht klassifizierbare Herzmuskelerkrankungen (NCCM). Unter den spezifischen Kardiomyopathien wurde die inflammatorische Kardiomyopathie als Myokarditis mit hämodynamischer Dysfunktion eingereiht. Eine virale Kardiomyopathie wurde als Persistenz viralen Genoms bei einer DCM definiert, die mit einer histologisch validierten Entzündung einhergehen kann. Inflammation liegt nach den Empfehlungen der WHF-Task Force vor, wenn sich ≥ 14 Lymphozyten und Makrophagen/mm2 in einer Myokardbiopsie finden. Dann liegt eine virale inflammatorische Kardiomyopathie oder Virusmyokarditis vor.Im Herzinsuffizienznetz geht das Projekt der Autoren von der Hypothese aus, dass die DCM ein genetisches Risikoprofil mit anderen Autoimmunkrankheiten teilt und deshalb verschiedene Gene (Polymorphismen) zusammen mit Umweltfaktoren zu autoimmunen Krankheitsbildern führen, zu denen auch die DCM zählt. Mit dieser Hypothese gut vereinbar sind der Nachweis von viraler DNA oder RNA im Myokard oder autoimmune Phänomene bei Patienten, z. T. auch ihren (noch) nicht betroffenen Angehörigen. Ungeklärt sind bisher allerdings die kausalen ätiopathogenetischen Verknüpfungen oder Trennlinien zwischen den beiden Befunden: So lassen sich bei einem Großteil der DCM-Patienten zirkulierende und biopsiegebundene organspezifische Autoantikörper, entzündliche Infiltrate und die Freisetzung proinflammatorischer Zytokine nachweisen. Andererseits ist anzunehmen, dass mindestens 20–30% der DCMs familiär gehäuft auftreten, allerdings ohne dass dabei in allen Fällen eine monogenetische Erkrankung vorliegen muss. Es ist anzunehmen, dass genetische Faktoren deshalb entweder als Suszeptibilitätsfaktoren für Umwelteinflüsse (wie eine Virusinfektion, Stress usw.) oder als direkte Determinanten des funktionellen und strukturellen Phänotyps Kardiomyopathie verantwortlich sind. Dabei ist es weiteren Untersuchungen vorbehalten zu klären, ob die Prädisposition für eine autoreaktive kardiale Schädigung sich derselben genetischen Mechanismen wie bei anderen Autoimmunerkrankungen bedient. Bemerkenswert ist die Prävalenz anderer autoimmuner Erkrankungen bei einem substantiellen Anteil von Indexpatienten mit DCM und Verwandten ersten Grades, wie z. B. juveniler Diabetes, Rheuma, Thyreoiditis, Psoriasis, Asthma usw., in eigenen bisherigen Untersuchungen.Die Autoren leiten daraus ab, dass für die Abschätzung des genetisch prädisponierenden Risikos auch Gene des MHC („major histocompatibility complex“) eine Rolle spielen, und haben sich in einem ersten Ansatz deren Untersuchung vorgenommen.

Genetic association study identifies HSPB7 as a risk gene for idiopathic dilated cardiomyopathy.

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.

Mutations in the ANKRD1 gene encoding CARP are responsible for human dilated cardiomyopathy

AIMS Dilated cardiomyopathy (DCM) is familial in approximately 30% of cases, and mutations have been identified in several genes. However, in a majority of familial cases, the responsible genes are still to be discovered. The ANKRD1 gene is over-expressed in heart failure in human and animal models. The encoded protein CARP interacts with partners such as myopalladin or titin, previously shown to be involved in DCM. We hypothesized that mutations in ANKRD1 could be responsible for DCM. METHODS AND RESULTS We sequenced the coding region of ANKRD1 from 231 independent DCM cases. We identified five missense mutations (three sporadic and two familial) absent from 400 controls and affecting highly conserved residues. Expression of the mutant CARP proteins after transfection in rat neonate cardiomyocytes indicated that most of them led to both significantly less repressor activity measured in a reporter gene assay and greater phenylephrin-induced hypertrophy, suggesting altered function of CARP mutant proteins. CONCLUSION On the basis of genetic and functional analysis of CARP mutations, we have identified ANKRD1 as a new gene associated with DCM, accounting for approximately 2% of cases.

Identification of mutational hot spots in LMNA encoding lamin A/C in patients with familial dilated cardiomyopathy

The familial form of dilated cardiomyopathy (DCM) occurs in about 20%–50% of DCM cases. It is a heterogenous 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 inportant 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.

A missense variant in desmoglein-2 predisposes to dilated cardiomyopathy.

Familial Dilated Cardiomyopathy (FDCM) is caused by mutations in genes encoding myocardial force transduction proteins. Desmoglein-2 (DSG2) and Desmocollin-2 (DSC2) provide cellular adhesion and force transduction by cell-to-cell anchorage. To test whether perturbations of DSG2 or DSC2 exhibit a pathogenic impact on DCM pathogenesis, we sequenced both genes in 73 patients with FDCM and assessed prevalence of missense variations in matched control cohorts. We detected two missense variations in DSG2 (V55M and V919G) which were absent in 360 control alleles. Surprisingly, both variants were previously reported in patients with arrhythmogenic right ventricular cardiomyopathy. Yet, in the present study only the DSG2-V55M variant showed segregation with DCM in a family pedigree. Subsequent, analysis of 538 patients with idiopathic DCM and 617 consecutive control individuals resulted in identification of thirteen DSG2-V55M carriers with DCM, whereas only three control subjects harbored the variant. DSG2 immunostaining revealed pale structures of the intercalated disc in myocardium of one unique homozygous DSG2-V55M carrier. Furthermore, myocardial desmosomal structures were significantly shortened when compared to DCM myocardium negative for DSG2-V55M. Thus, our study identified the DSG2-V55M polymorphism as a novel risk variant for DCM associated with shortened desmosomes of the cardiac intercalated disc.

Management of patients with suspected (peri-)myocarditis and inflammatory dilated cardiomyopathy.

Inflammatory cardiomyopathy and myocarditis are considered acquired forms of dilated cardiomyopathy. Whereas consensus documents on the diagnosis of myocarditis and perimyocarditis do exist, guidelines on the specific treatment have been established only for the management of pericardial diseases, which at least partly can be applied in analogy to myocarditis. Presently, feasible clinical pathways are available, which can lead to a correct diagnosis and specific treatment. This is illustrated with two cases of fulminant myocarditis, in one with successful diagnosis and treatment of a cardiac sarcoid and another one in which diagnostic nihilism led to a lethal outcome in giant cell myocarditis at necropsy. A case of active parvo B19-positive myocarditis demonstrates the role of immunoglobulin treatment under these conditions.ZusammenfassungMyokarditis und inflammatorische Kardiomyopathie gehören zu den erworbenen Kardiomyopathieformen. Gegenwärtig gibt es zwar Konsensusdokumente zur adäquaten Diagnostik der Myokarditis sowie eine Leitlinie der European Society of Cardiology zur Perikarditis, aber keine Leitlinien zur Therapie der Myokarditis, so dass wir auf rationale Behandlungspfade in der Betreuung von Patienten mit entzündlichen Myokarderkrankungen angewiesen sind. Der Sinn der Behandlungspfade wird anhand deren erfolgreicher Anwendung bei fulminanter Myokarditis und Herzsarkoidose sowie einer mit i.v. Immunglobulinen behandelten Parvo-B19-assoziierten Myokarditis illustriert. Diagnostischer Nihilismus führte in einem weiteren Fall erst post mortem zur korrekten Diagnose.

Cardiomyopathies: Classification, Diagnosis, and Treatment

This article comments on the recent classifications of cardiomyopathies by the American Heart Association and the European Society of Cardiology with respect to their clinical applicability. Taking them and the statement on the role of endomyocardial biopsies in different clinical scenarios together, the clinician is now able to identify genetic, autoimmune, and viral causative factors by using a thorough and logical approach to reach a diagnosis in patients with familial and nonfamilial forms of the underlying structural heart muscle diseases. In this overview, a special emphasis is also placed on the management of inflammatory and viral cardiomyopathies.

Familial inflammatory dilated cardiomyopathy

Systematic family screening has recently identified dilated cardiomyopathy as an inherited disorder in up to 30% of cases. Mutations in genes encoding proteins responsible for myocardial architecture have been identified, but additional pathophysiological mechanisms including inflammatory reactions have been proposed.

Kardiomyopathien und Myokardbiopsie im Spiegel der neuen Klassifikationen

ZusammenfassungEine erste Klassifikation der Kardiomyopathien wurde 1980 durch die World Health Organization und die International Society and Federation of Cardiology (WHO/ISFC) erstellt. 1996 wurde sie um die Kategorien der spezifischen Kardiomyopathien inklusive der Myokarditis und der arrhythmogenen rechtsventrikulären Kardiomyopathie erweitert und beschrieb Kardiomyopathien als „Erkrankungen des Myokards mit kardialer Dysfunktion“, die die Phänotypen einer dilatativen (DCM), restriktiven (RCM), hypertrophen (HCM) und arrhythmogenen rechtsventrikulären Kardiomyopathie (ARVC) unterscheidet. Zu den spezifischen Kardiomyopathien zählten seither Herzmuskelerkrankungen, die durch spezifische kardiale oder Systemerkrankungen wie myokardiale Entzündung (Myokarditis, inflammatorische Kardiomyopathie), Morbus Fabry, Amyloidose o.Ä. hervorgerufen werden. 1999 wurden im Rahmen eines Konsensustreffens der World Heart Federation die Kriterien der inflammatorischen Kardiomyopathie und der molekularen Differenzierung der Ätiologie (viral, bakteriell, autoimmun) definiert.Untersuchungen zu genetischen Ursachen von familiär gehäuft auftretenden Kardiomyopathien führten zu der Auffassung, dass eine Reihe von Kardiomyopathien die Konsequenz eines einzelnen Gendefekts (monogen) und damit angeboren ist. Als genomische/postgenomische Klassifikation der angeborenen Kardiomyopathien wurde vorgeschlagen, Erkrankungen des Zytoskeletts (DCM, ARVC), des Sarkomers (HCM, RCM) und der Ionenkanäle (Long- und Short-QT-Syndrom, Brugada-Syndrom, katecholaminerge polymorphe ventrikuläre Tachykardien) zu unterscheiden. Anfang 2006 wurde dann eine Einteilung der Kardiomyopathien von der American Heart Association (AHA) publiziert, die der möglichen Dominanz genetischer Veränderungen als Ursache der Kardiomyopathien Rechnung tragen sollte. Diese Einteilung blieb nicht unwidersprochen.Die Arbeitsgruppe für Myo- und Perikarderkrankungen der Europäischen Gesellschaft für Kardiologie überarbeitete die Klassifikation von 1995, die sich am klinischen Phänotyp orientiert hatte, mit dem Ziel, die Kardiomyopathien weiterhin bezüglich ihrer morphologischen und funktionellen Phänotypen einzuteilen und die unnötige Unterscheidung zwischen primären und sekundären Kardiomyopathien zu vermeiden. Kardiomyopathien werden in der neuen europäischen Klassifikation als myokardiale Erkrankungen bezeichnet, die einen strukturell oder funktionell veränderten Herzmuskel in Abwesenheit einer koronaren Herzerkrankung, eines Hochdrucks, einer Herzklappen- oder angeborenen Herzerkrankung aufweisen. Parallel dazu wurde im Jahr 2007 eine Empfehlung der AHA und des American College of Cardiology unter Beteiligung einer europäischen Vertretung zur Entnahme von Endomyokardbiopsien für die klinische Praxis veröffentlicht. Diese definiert insgesamt 14 klinische Szenarien, bei denen die Biopsieentnahme eine diagnostische, prognostische und therapeutische Relevanz hat, und versieht diese mit Evidenzgraden. Die Einteilung erfolgte bewusst aufgrund klinischer Symptome und Befunde, mit denen sich Patienten im klinischen Alltag vorstellen.Unter Zugrundelegung beider Klassifikationen der Kardiomyopathien zusammen mit der klinischen Empfehlung zur Durchführung von Endomyokardbiopsien besitzt der Kliniker nun einen auf Expertenmeinung und Studien beruhenden Behandlungsrahmen. Die Erfassung von Ätiologie und Pathophysiologie struktureller Herzmuskelerkrankungen durch Erhebung der Familienanamnese, die Durchführung genetischer Untersuchungen sowie immunhistochemische und molekularbiologische Untersuchungen der Endomyokardbiopsien sind damit in ein etabliertes diagnostischen Konzept eingebunden und ermöglichen eine in Studien und Register dokumentierte Therapie.AbstractThe first classifications of cardiomyopathies from 1980 and 1996 described them as heart muscle diseases, with dilated (DCM), hypertrophic (HCM), restrictive (RCM), arrhythmogenic right ventricular (ARVC), and nonclassifiable cardiomyopathies. Furthermore, the World Health Organization/International Society and Federation of Cardiology (WHO/ISFC) classification from 1996 listed among the specific cardiomyopathies inflammatory cardiomyopathy as a new and distinct entity, which was defined histologically as myocarditis in association with cardiac dysfunction. Infectious and autoimmune forms of inflammatory cardiomyopathy were recognized. Viral cardiomyopathy was defined as viral persistence in a dilated heart without ongoing inflammation. If it was accompanied by myocardial inflammation, it was termed inflammatory viral cardiomyopathy (or viral myocarditis with cardiomegaly). This entity was further elucidated in a World Heart Federation consensus meeting in 1999 by quantitative immunohistological criteria (< 14 infiltrating cells/mm2) and the etiology by molecular biological methods, e.g., polymerase chain reaction, as viral, bacterial, or autoimmune (= nonmicrobial).The development of molecular genetics, with the discovery of a genetic background in several forms of cardiomyopathies previously alluded to as “of unknown origin”, was the origin of a debate on a new classification based on genomics. A genomic/postgenomic classification was postulated taking the underlying gene mutations and the cellular level of expression of encoded proteins into account, thus distinguishing cytoskeleton (cytoskeletalopathies, e.g., DCM or ARVC), sarcomeric (sarcomyopathies as in HCM and RCM) and ion channel (channelopathies, e.g., long or short QT syndrome and Brugada’s syndrome) cardiomyopathies. Such a classification of cardiomyopathies was proposed in 2006 by the American Heart Association (AHA), which took the rapid evolution of molecular genetics in cardiology into account. It also introduced several recently described diseases, and is unique in that it incorporated ion channelopathies even without hemodynamic dysfunction as a “primary” cardiomyopathy.The ESC (European Society of Cardiology) Working Group on Myocardial and Pericardial Diseases has deliberately taken a different approach based on a clinically oriented classification in which heart muscle disorders were grouped according to morphology and function. This obviously remains the clinically most useful approach for the diagnosis and management of patients and families with heart muscle disease. In the ESC position statement published in 2008, cardiomyopathies were defined as myocardial disorders in which the heart muscle is structurally and functionally abnormal, and in which coronary artery disease, hypertension, valvular and congenital heart disease are absent or do not sufficiently explain the observed myocardial abnormality. The aim was to help clinicians look beyond generic diagnostic labels in order to reach more specific diagnoses. In parallel, a scientific statement on the role of endomyocardial biopsy in the management of cardiovascular disease was published at the end of 2007 making useful recommendations for clinical practice and providing an understanding for the use of endomyocardial biopsy in an individual patient.Taking the classification of cardiomyopathies and the statement on the role of endomyocardial biopsies in different clinical scenarios together, the clinician is now able to identify genetic, autoimmune and viral causative factors by using a thorough and logical approach to reach a diagnosis in patients with familial and nonfamilial forms of the underlying structural heart muscle diseases.

Novel mutations in the sarcomeric protein myopalladin in patients with dilated cardiomyopathy

Recently, missense mutations in titin-associated proteins have been linked to the pathogenesis of dilated cardiomyopathy (DCM). The objective of this study was to search for novel disease-associated mutations in the two human titin-binding proteins myopalladin and its amino-terminal-interacting partner cardiac ankyrin-repeat protein (CARP). In a cohort of 255 cases with familial and sporadic DCM, we analyzed the coding regions and all corresponding intron flanks located in the MYPN and CARP-encoding ANKRD1 gene. Two heterozygous missense mutations were detected in the MYPN gene (p.R955W and p.P961L), but neither of these mutations was found in 300 healthy controls. Both mutations were located in the α-actinin-binding region of myopalladin. Endomyocardial biopsies from the p.R955W carrier showed normal subcellular localization of myopalladin and α-actinin in cardiac myocytes, while their regular sarcomeric staining pattern was significantly disrupted in the p.P961L carrier, indicating that disturbed myofibrillogenesis and altered sarcomere assembly are the cause of the disease. In the ANKRD1 gene, we identified synonymous base exchanges (c.108T>C and c.-79C>T, respectively), but no non-synonymous mutations. In summary, we have identified novel missense mutations in the third immunoglobulin-like domain of myopalladin, which have either no or profound effects on the molecular composition of the sarcomere. According to our epidemiological data, the prevalence of ANKRD1 mutations seems to be lower than that of its binding partner myopalladin, indicating the clinical significance of myopalladin for the functional integrity of the sarcomeric apparatus and the protection against DCM.