Clinical and genetic characterization of families with arrhythmogenic right ventricular dysplasia/cardiomyopathy provides novel insights into patterns of disease expression

Desmosomal molecules in and out of adhering junctions: normal and diseased States of epidermal, cardiac and mesenchymally derived cells

Current cell biology textbooks mention only two kinds of cell-to-cell adhering junctions coated with the cytoplasmic plaques: the desmosomes (maculae adhaerentes), anchoring intermediate-sized filaments (IFs), and the actin microfilament-anchoring adherens junctions (AJs), including both punctate (puncta adhaerentia) and elongate (fasciae adhaerentes) structures. In addition, however, a series of other junction types has been identified and characterized which contain desmosomal molecules but do not fit the definition of desmosomes. Of these special cell-cell junctions containing desmosomal glycoproteins or proteins we review the composite junctions (areae compositae) connecting the cardiomyocytes of mature mammalian hearts and their importance in relation to human arrhythmogenic cardiomyopathies. We also emphasize the various plakophilin-2-positive plaques in AJs (coniunctiones adhaerentes) connecting proliferatively active mesenchymally-derived cells, including interstitial cells of the heart and several soft tissue tumor cell types. Moreover, desmoplakin has also been recognized as a constituent of the plaques of the complexus adhaerentes connecting certain lymphatic endothelial cells. Finally, we emphasize the occurrence of the desmosomal transmembrane glycoprotein, desmoglein Dsg2, out of the context of any junction as dispersed cell surface molecules in certain types of melanoma cells and melanocytes. This broadening of our knowledge on the diversity of AJ structures indicates that it may still be too premature to close the textbook chapters on cell-cell junctions.

Lack of uniform progression of endocardial scar in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy and ventricular tachycardia

BACKGROUND

The endocardial substrate for ventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is thought to be caused by a progressive degenerative process. Many clinical decisions and treatment plans are guided by this pathophysiologic assumption, but the extent of progression of macroscopic endocardial scar and right ventricular (RV) dilatation have not been assessed.

METHODS AND RESULTS

Eleven patients with ARVD/C and ventricular tachycardia had 2 detailed sinus rhythm electroanatomic endocardial voltage maps (average, 291+/-122 points per map; range, 114 to 558 points) performed a mean of 57 months apart (minimum, 9 months) as part of ventricular tachycardia ablation procedures. Voltage-defined scar (<1.5 mV) and RV volume were measured by area and volume measurement software and compared. Two of the 11 patients had a clear increase in scar area (47 cm(2); 32 cm(2)) confirmed by visual inspection. The remaining 9 (81%; 95% CI, 48% to 98%) patients had no increase (<10-cm(2) difference) in scar area between studies. In contrast, 10 of the 11 patients had a significant increase in RV volume, with an average increase of 24% (212+/-67 mL to 263+/-52 mL; P< or =0.01).

CONCLUSIONS

In patients with ARVD/C and ventricular tachycardia, progressive RV dilatation is the rule, and rapid progression of significant macroscopic endocardial scar occurs in only a subset of patients. These results have important management implications, suggesting that efforts to prevent RV dilatation in this population are needed and that an aggressive substrate-based ablation strategy offers the potential to provide long-term ventricular tachycardia control.

Arrhythmogenic cardiomyopathy: etiology, diagnosis, and treatment

Arrhythmogenic right ventricular cardiomyopathy (ARVC) has a prevalence of at least 1 in 1000, is a leading cause of sudden cardiac death in people aged < or =35 years, and accounts for up to 10% of deaths from undiagnosed cardiac disease in the <65 age group. The classic form of the disease has an early predilection for the right ventricle, but recognition of left-dominant and biventricular subtypes has prompted proposal of the broader term arrhythmogenic cardiomyopathy. The clinical profile of the disease bridges the gap between the cardiomyopathies and inherited arrhythmia syndromes. The early "concealed" phase is characterized by propensity toward ventricular tachyarrhythmia in the setting of well-preserved morphology, histology, and ventricular function. As the disease progresses, however, myocyte loss, inflammation, and fibroadiposis become evident. Up to 40% of cases harbor rare variants in genes encoding components of the desmosome, specialized intercellular junctions that confer mechanical strength to cardiac and epithelial tissue, and may also participate in signaling networks. Phenotypic heterogeneity and the nonspecific nature of associated features complicate clinical diagnosis, which requires multipronged cardiovascular investigation rather than a single test. Development of a prospectively validated risk-stratification algorithm for the full disease spectrum remains the foremost clinical challenge.

Desmosomal gene analysis in arrhythmogenic right ventricular dysplasia/cardiomyopathy: spectrum of mutations and clinical impact in practice

AIMS

Five desmosomal genes have been recently implicated in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) but the clinical impact of genetics remains poorly understood. We wanted to address the potential impact of genotyping.

METHODS AND RESULTS

Direct sequencing of the five genes (JUP, DSP, PKP2, DSG2, and DSC2) was performed in 135 unrelated patients with ARVD/C. We identified 41 different disease-causing mutations, including 28 novel ones, in 62 patients (46%). In addition, a genetic variant of unknown significance was identified in nine additional patients (7%). Distribution of genes was 31% (PKP2), 10% (DSG2), 4.5% (DSP), 1.5% (DSC2), and 0% (JUP). The presence of desmosomal mutations was not associated with familial context but was associated with young age, symptoms, electrical substrate, and extensive structural damage. When compared with other genes, DSG2 mutations were associated with more frequent left ventricular involvement (P = 0.006). Finally, complex genetic status with multiple mutations was identified in 4% of patients and was associated with more frequent sudden death (P = 0.047).

CONCLUSION

This study supports the use of genetic testing as a new diagnostic tool in ARVC/D and also suggests a prognostic impact, as the severity of the disease appears different according to the underlying gene or the presence of multiple mutations.

Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria

BACKGROUND

In 1994, an International Task Force proposed criteria for the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) that facilitated recognition and interpretation of the frequently nonspecific clinical features of ARVC/D. This enabled confirmatory clinical diagnosis in index cases through exclusion of phenocopies and provided a standard on which clinical research and genetic studies could be based. Structural, histological, electrocardiographic, arrhythmic, and familial features of the disease were incorporated into the criteria, subdivided into major and minor categories according to the specificity of their association with ARVC/D. At that time, clinical experience with ARVC/D was dominated by symptomatic index cases and sudden cardiac death victims-the overt or severe end of the disease spectrum. Consequently, the 1994 criteria were highly specific but lacked sensitivity for early and familial disease.

METHODS AND RESULTS

Revision of the diagnostic criteria provides guidance on the role of emerging diagnostic modalities and advances in the genetics of ARVC/D. The criteria have been modified to incorporate new knowledge and technology to improve diagnostic sensitivity, but with the important requisite of maintaining diagnostic specificity. The approach of classifying structural, histological, electrocardiographic, arrhythmic, and genetic features of the disease as major and minor criteria has been maintained. In this modification of the Task Force criteria, quantitative criteria are proposed and abnormalities are defined on the basis of comparison with normal subject data.

CONCLUSIONS

The present modifications of the Task Force Criteria represent a working framework to improve the diagnosis and management of this condition.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00024505.

Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the Task Force Criteria

BACKGROUND

In 1994, an International Task Force proposed criteria for the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) that facilitated recognition and interpretation of the frequently nonspecific clinical features of ARVC/D. This enabled confirmatory clinical diagnosis in index cases through exclusion of phenocopies and provided a standard on which clinical research and genetic studies could be based. Structural, histological, electrocardiographic, arrhythmic, and familial features of the disease were incorporated into the criteria, subdivided into major and minor categories according to the specificity of their association with ARVC/D. At that time, clinical experience with ARVC/D was dominated by symptomatic index cases and sudden cardiac death victims-the overt or severe end of the disease spectrum. Consequently, the 1994 criteria were highly specific but lacked sensitivity for early and familial disease.

METHODS AND RESULTS

Revision of the diagnostic criteria provides guidance on the role of emerging diagnostic modalities and advances in the genetics of ARVC/D. The criteria have been modified to incorporate new knowledge and technology to improve diagnostic sensitivity, but with the important requisite of maintaining diagnostic specificity. The approach of classifying structural, histological, electrocardiographic, arrhythmic, and genetic features of the disease as major and minor criteria has been maintained. In this modification of the Task Force criteria, quantitative criteria are proposed and abnormalities are defined on the basis of comparison with normal subject data.

CONCLUSIONS

The present modifications of the Task Force Criteria represent a working framework to improve the diagnosis and management of this condition. Clinical Trial Registration clinicaltrials.gov Identifier: NCT00024505.

Prevalence of left ventricular regional dysfunction in arrhythmogenic right ventricular dysplasia: a tagged MRI study

BACKGROUND

Although arrhythmogenic right ventricular dysplasia (ARVD) predominantly affects the right ventricle (RV), genetic/molecular and histological changes are biventricular. Regional left ventricular (LV) function has not been systematically studied in ARVD.

METHODS AND RESULTS

The study population included 21 patients with suspected ARVD who underwent evaluation with MRI including tagging. Eleven healthy volunteers served as control subjects. Peak systolic regional circumferential strain (Ecc, %) was calculated by harmonic phase from tagged MRI based on the 16-segment model. Patients who met ARVD Task Force criteria were classified as definite ARVD, whereas patients with a positive family history who had 1 additional minor criterion and patients without a family history with 1 major or 2 minor criteria were classified as probable ARVD. Of the 21 ARVD subjects, 11 had definite ARVD and 10 had probable ARVD. Compared with control subjects, probable ARVD patients had similar RV ejection fraction (58.9+/-6.2% versus 53.5+/-7.6%, P=0.20), but definite ARVD patients had significantly reduced RV ejection fraction (58.9+/-6.2% versus 45.2+/-6.0%, P=0.001). LV ejection fraction was similar in all 3 groups. Compared with control subjects, peak systolic Ecc was significantly less negative in 6 of 16 (37.5%) segments in definite ARVD and 3 of 16 segments (18.7%) in probable ARVD (all P<0.05).

CONCLUSIONS

ARVD is associated with regional LV dysfunction, which appears to parallel degree of RV dysfunction. Further large studies are needed to validate this finding and to better define implications of subclinical segmental LV dysfunction.

A case of cardiac sarcoidosis masquerading as arrhythmogenic right ventricular cardiomyopathy awaiting heart transplant

We report a case of 45-year-old man, who was diagnosed with arrhythmogenic right ventricular cardiomyopathy (ARVC) and presented with right ventricular (RV) enlargement with a global decrease in RV contractility accompanied by impairment of left ventricular function. He was placed on the heart transplant waiting list. Endomyocardial biopsy from RV septal wall did not show any evidence of sarcoidosis or inflammatory change. Four years after he was put on the heart transplant waiting list, a computed tomography chest scan for the purpose of anatomical evaluation for coronary sinus prior to biventricular pacing lead implantation incidentally showed bilateral hilar lymphadenopathy, which suggested the possibility of sarcoidosis. Biopsy of the inguinal lymph node pathologically was consistent with sarcoidosis. The 2[¹⁸F]fluoro-2-deoxy-d-glucose positron emission tomography scanning (FDG-PET) demonstrated intense uptake in the myocardium, and the patient was finally diagnosed as having cardiac sarcoidosis. After steroid treatment, the abnormal FDG-PET uptake disappeared. The patient therefore represented a case of cardiac sarcoidosis masquerading as ARVC. It should be recognized that RV involvement is one of the manifestations in cardiac sarcoidosis.

Progress with genetic cardiomyopathies: screening, counseling, and testing in dilated, hypertrophic, and arrhythmogenic right ventricular dysplasia/cardiomyopathy

This review focuses on the genetic cardiomyopathies: principally dilated cardiomyopathy, with salient features of hypertrophic cardiomyopathy and arrhythmogenic right ventricular dysplasia/cardiomyopathy, regarding genetic etiology, genetic testing, and genetic counseling. Enormous progress has recently been made in identifying genetic causes for each cardiomyopathy, and key phenotype and genotype information is reviewed. Clinical genetic testing is rapidly emerging with a principal rationale of identifying at-risk asymptomatic or disease-free relatives. Knowledge of a disease-causing mutation can guide clinical surveillance for disease onset, thereby enhancing preventive and treatment interventions. Genetic counseling is also indicated for patients and their family members regarding the symptoms of their cardiomyopathy, its inheritance pattern, family screening recommendations, and genetic testing options and possible results.

Role of genetic testing in arrhythmogenic right ventricular cardiomyopathy/dysplasia

In a cohort of patients with confirmed or suspected arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), genetic testing is useful in confirming the diagnosis, particularly in individuals who do not completely fulfil Task Force criteria for the disease, thereby also enabling the adoption of preventive measures in family members. Due to the high percentage of novel mutations that are expected to be identified in ARVC/D, the use of genetic screening technology based on the identification of known mutations seems to have very restricted value. Our results support that the presence of certain genetic variations could play a role in the final phenotype of patients with ARVC/D, where single and compound mutation carriers would have more symptomatic forms of the disease and the polymorphism P366L could be associated to a more benign phenotype.

The junctions that don't fit the scheme: special symmetrical cell-cell junctions of their own kind

Immunocytochemical, electron-, and immunoelectron-microscopical studies have revealed that, in addition to the four major "textbook categories" of cell-cell junctions (gap junctions, tight junctions, adherens junctions, and desmosomes), a broad range of other junctions exists, such as the tiny puncta adhaerentia minima, the taproot junctions (manubria adhaerentia), the plakophilin-2-containing adherens junctions of mesenchymal or mesenchymally derived cell types including malignantly transformed cells, the composite junctions (areae compositae) of the mature mammalian myocardium, the cortex adhaerens of the eye lens, the interdesmosomal "sandwich" or "stud" junctions in the subapical layers of stratified epithelia and the tumors derived therefrom, and the complexus adhaerentes of the endothelial and virgultar cells of the lymph node sinus. On the basis of their sizes and shapes, other morphological criteria, and their specific molecular ensembles, these junctions and the genes that encode them cannot be subsumed under one of the major categories mentioned above but represent special structures in their own right, appear to serve special functions, and can give rise to specific pathological disorders.

Desmoglein-2 and desmocollin-2 mutations in dutch arrhythmogenic right ventricular dysplasia/cardiomypathy patients: results from a multicenter study

BACKGROUND

This study aimed to evaluate the prevalence and type of mutations in the major desmosomal genes, Plakophilin-2 (PKP2), Desmoglein-2 (DSG2), and Desmocollin-2 (DSC2), in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) patients. We also aimed to distinguish relevant clinical and ECG parameters.

METHODS AND RESULTS

Clinical evaluation was performed according to the Task Force Criteria (TFC). We analyzed the genes in (a) 57 patients who fulfilled the ARVD/C TFC (TFC+), (b) 28 patients with probable ARVD/C (1 major and 1 minor, or 3 minor criteria), and (c) 31 patients with 2 minor or 1 major criteria. In the TFC+ ARVD/C group, 23 patients (40%) had PKP2 mutations, 4 (7%) had DSG2 mutations, and 1 patient (2%) carried a mutation in DSC2, whereas 1 patient (2%) had a mutation in both DSG2 and DSC2. Among the DSG2 and DSC2 mutation-positive TFC+ ARVD/C probands, 2 carried compound heterozygous mutations and 1 had digenic mutations. In probable ARVD/C patients and those with 2 minor or 1 major criteria for ARVD/C, mutations were less frequent and they were all heterozygous. Negative T waves in the precordial leads were observed more (P<0.002) among mutation carriers than noncarriers and in particular in PKP2 mutation carriers.

CONCLUSIONS

Mutations in DSG2 and DSC2 are together less prevalent (10%) than PKP2 mutations (40%) in Dutch TFC+ ARVD/C patients. Interestingly, biallelic or digenic DSC2 and/or DSG2 mutations are frequently identified in TFC+ ARVD/C patients, suggesting that a single mutation is less likely to cause a full-blown ARVD/C phenotype. Negative T waves on ECG were prevalent among mutation carriers (P<0.002).

Penetrance and risk profile in inherited cardiac diseases studied in a dedicated screening clinic

Genetically transmitted cardiomyopathies can affect several members in a family. Identification of high-risk patients could lead to a preventive treatment. We report the results of a 5-year experience of a dedicated clinic. Family screening was offered to 493 consecutive unrelated patients; 2,328 subjects (40 +/- 19 years old, 52% men) were evaluated (mean 4.4 relatives/family). Electrocardiography and echocardiography were performed in all cases; additional tests were indicated depending on the disease. Familial study was recommended because of a proband with hypertrophic cardiomyopathy (HC) in 57%, idiopathic dilated cardiomyopathy (IDC) in 14%, arrhythmogenic right ventricular cardiomyopathy (ARVC) in 2%, left ventricular noncompaction in 2%, Brugada syndrome (BS) in 15%, long QT syndrome (LQTS) in 3%, and other conditions in 6%. Familial disease was confirmed in 164 (39%); 43% with HC, 47% with IDC, 25% with ARVC, 33% with left ventricular noncompaction, 28% with BS, and 30% with LQTS. Two hundred twenty-two (44 +/- 20 years old, 60% men) affected relatives were identified (129 of whom were newly diagnosed). Sixty-four patients were newly diagnosed with HC, 40 with IDC, 2 with ARVC, 5 with left ventricular noncompaction, 14 with BS, and 2 with LQTS, in whom appropriate risk stratification and medication, if needed, were initiated (specific medication in 40, 31.0%). Cardioverter-defibrillator implantation was indicated in 4 relatives for primary prevention. Ninety-two (18.7%) had a family history of sudden death (FHSCD). Consanguinity was rare but significantly associated to a higher percentage of family disease (75.0% vs 38.3%, p = 0.003) and family history of sudden death (42.1% vs 17.8, p <0.001). In conclusion, the prevalence of familial disease in inherited cardiac conditions is high. Systematic familial study identified many asymptomatic affected patients who could benefit from early treatment to prevent complications. Dedicated clinics and multidisciplinary teams are needed for proper screening programs.

Genetic testing in specific cardiomyopathies

An increasing number of genetic tests for cardiomyopathies are becoming available for clinical use. This commentary will give a short overview of indications and challenges concerning genetic testing for these conditions.

Proteomic analysis reveals significant elevation of heat shock protein 70 in patients with chronic heart failure due to arrhythmogenic right ventricular cardiomyopathy

As proteins are the ultimate biological determinants of phenotype of disease, we screened altered proteins associated with heart failure due to arrhythmogenic right ventricular cardiomyopathy (ARVC) to identify biomarkers potential for rapid diagnosis of heart failure. By 2-dimensional gel electrophoresis and mass spectrometry, we identified five commonly altered proteins with more than 1.5 fold changes in eight ARVC failing hearts using eight non-failing hearts as reference. Noticeably, one of the altered proteins, heat shock protein 70 (HSP70), was increased by 1.64 fold in ARVC failing hearts compared with non-failing hearts. The increase of cardiac HSP70 was further validated by Western blot, immunochemistry, and enzyme-linked immunosorbent assay (ELISA) in failing hearts due to not only ARVC, but also dilated (DCM, n = 18) and ischemic cardiomyopathy (ICM, n = 8). Serum HSP70 was also observed to be significantly increased in heart failure patients derived from the three forms of cardiomyopathies. In addition, we observed hypoxia/serum depletion stimulation induced significantly elevation of intracellular and extracellular HSP70 in cultured neonatal rat cardiomyocytes. For the first time to our knowledge, we revealed and clearly demonstrated significant up-regulation of cardiac and serum HSP70 in ARVC heart failure patients. Our results indicate that elevated HSP70 is the common feature of heart failure due to ARVC, DCM, and ICM, which suggests that HSP70 may be used as a biomarker for the presence of heart failure due to cardiomyopathies of different etiologies and may hold diagnostic/prognostic potential in clinical practice.

Comprehensive desmosome mutation analysis in north americans with arrhythmogenic right ventricular dysplasia/cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited disorder typically caused by mutations in components of the cardiac desmosome. The prevalence and significance of desmosome mutations among patients with ARVD/C in North America have not been described previously. We report comprehensive desmosome genetic analysis for 100 North Americans with clinically confirmed or suspected ARVD/C.

METHODS AND RESULTS

In 82 individuals with ARVD/C and 18 people with suspected ARVD/C, DNA sequence analysis was performed on PKP2, DSG2, DSP, DSC2, and JUP. In those with ARVD/C, 52% harbored a desmosome mutation. A majority of these mutations occurred in PKP2. Notably, 3 of the individuals studied have a mutation in more than 1 gene. Patients with a desmosome mutation were more likely to have experienced ventricular tachycardia (73% versus 44%), and they presented at a younger age (33 versus 41 years) compared with those without a desmosome mutation. Men with ARVD/C were more likely than women to carry a desmosome mutation (63% versus 38%). A mutation was identified in 5 of 18 patients (28%) with suspected ARVD. In this smaller subgroup, there were no significant phenotypic differences identified between individuals with a desmosome mutation compared with those without a mutation.

CONCLUSIONS

Our study shows that in 52% of North Americans with ARVD/C a mutation in one of the cardiac desmosome genes can be identified. Compared with those without a desmosome gene mutation, individuals with a desmosome gene mutation had earlier-onset ARVD/C and were more likely to have ventricular tachycardia.

Morphologic variants of familial arrhythmogenic right ventricular dysplasia/cardiomyopathy a genetics-magnetic resonance imaging correlation study

OBJECTIVES

The purpose of this study was to determine the extent of left ventricular (LV) involvement in individuals predisposed to developing arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), and to investigate novel morphologic variants of ARVD/C.

BACKGROUND

The discovery of desmosomal mutations associated with ARVD/C has led researchers to hypothesize equal right ventricular (RV) and LV affliction in the disease process.

METHODS

Thirty-eight (age 30 +/- 17 years; 18 males) family members of 12 desmosomal mutation-carrying ARVD/C probands underwent genotyping and cardiac magnetic resonance imaging (CMR). The CMR investigators were blinded to clinical and genetic data.

RESULTS

Twenty-five individuals had mutations in PKP2, DSP, and/or DSG2 genes. RV abnormalities were associated with the presence of mutation(s) and with disease severity determined by criteria (minor = 1; major = 2) points for ARVD/C diagnosis. The only LV abnormality detected, the presence of intramyocardial fat, was present in 4 individuals. Each of these individuals was a mutation carrier, whereas 1 had no previously described ARVD/C-related abnormality. On detailed CMR, a focal "crinkling" of the RV outflow tract and subtricuspid regions ("accordion sign") was observed in 60% of the mutation carriers and none of the noncarriers (p < 0.001). The sign was present in 0%, 37%, 71%, and 75% of individuals who met 1, 2, 3, and 4+ criteria points, respectively (p < 0.01).

CONCLUSIONS

Despite a possible LV involvement in ARVD/C, the overall LV structure and function are well preserved. Independent LV involvement is of rare occurrence. The accordion sign is a promising tool for early diagnosis of ARVD/C. Its diagnostic utility should be confirmed in larger cohorts.

Electrocardiographic pattern in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a cardiac disease characterized by progressive myocardial atrophy and fibrofatty replacement. Standard electrocardiograms (ECGs) and signal-averaged ECGs (SAECGs) were relatively low cost and repeatable diagnostic tools. In this study, ECGs and SAECGs of patients with ARVC were analyzed with the aim to assess the diagnostic capability of these noninvasive techniques. A total of 205 patients with ARVC were analyzed. ECGs were abnormal in 74% of patients and SAECGs were positive in 60%, with normal ECGs mostly related to mild forms of the disease. The most common electrocardiographic abnormalities were localized right QRS prolongation, poor r wave progression in the right precordial leads, incomplete right branch bundle block, prolonged S-wave upstroke in V(1) to V(3), parietal block, ST-segment elevation in V(1) to V(3), inversion of T waves beyond V(2), and epsilon wave. Low QRS voltages in the precordial leads were frequently present in all patients with ARVC compared with a group of 120 healthy subjects (p = 0.00001). T-wave inversion beyond V(3) characterized subjects with severe right ventricular dilatation, whereas in subjects with left ventricular involvement, T-wave inversion in lateral leads was more commonly detected. Overall, the extent of electrocardiographic abnormalities was related to disease extent. In conclusion, abnormalities in ECGs and SAECGs were frequent in patients with ARVC and correlated with disease extent, even if a stereotypical electrocardiographic pattern did not exist. ECGs and SAECGs remain an important tool for the diagnosis and assessment of ARVC extent. Nonetheless, a normal ECG does not exclude the presence of the disease.

Arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy is a rare inherited heart-muscle disease that is a cause of sudden death in young people and athletes. Causative mutations in genes encoding desmosomal proteins have been identified and the disease is nowadays regarded as a genetically determined myocardial dystrophy. The left ventricle is so frequently involved as to support the adoption of the broad term arrhythmogenic cardiomyopathy. Clinical diagnosis can be achieved by demonstrating function and structure changes of the right ventricle, electrocardiogram depolarisation and repolarisation abnormalities, ventricular arrhythmias, and fibrofatty replacement through endomyocardial biopsy. Although specific, the standardised diagnostic criteria lack sensitivity for early disease and their primary application remains in establishing the diagnosis in probands. However, the main clinical targets are early detection of concealed forms and risk stratification for preventive strategies, which include physical exercise restriction, antiarrhythmic drugs, and implantable cardioverter-defibrillator therapy. Cascade genetic screening of family members of gene-positive probands allows the identification of asymptomatic carriers who would require lifelong follow-up due to the age-related penetrance.

Upregulated expression of cardiac ankyrin repeat protein in human failing hearts due to arrhythmogenic right ventricular cardiomyopathy

AIMS

Expression of cardiac ankyrin repeat protein (CARP) is augmented in heart failure due to dilated or ischaemic cardiomyopathy. It is unclear whether CARP is upregulated in heart failure due to arrhythmogenic right ventricular cardiomyopathy (ARVC). In the present study, we investigated the expression pattern of CARP and the correlation between CARP and the well-known heart failure marker pro-atrial natriuretic peptide (proANP) in ARVC failing hearts.

METHODS AND RESULTS

Gene microarray analysis demonstrated increased CARP expression in ARVC failing hearts compared with non-failing control hearts, which was further validated by real-time RT-PCR, western blot, and ELISA at the mRNA and protein levels. Fractionation experiments revealed that the upregulation of CARP expression is restricted to the nuclei of residual cardiac cells in ARVC failing hearts. Regression analysis showed a positive correlation between CARP and proANP in ARVC failing hearts.

CONCLUSION

Augmented CARP expression may be a common molecular event in failing hearts regardless of cardiomyopathic aetiology. The upregulation of nuclear CARP expression and positive correlation between cardiac CARP and proANP suggests that CARP may be used as a genetic marker existing in the nuclei in contrast to proANP existing in the cytosol of cardiac cells in heart failure patients.

Canadian Cardiovascular Society Consensus Conference guidelines on heart failure, update 2009: diagnosis and management of right-sided heart failure, myocarditis, device therapy and recent important clinical trials

The Canadian Cardiovascular Society published a comprehensive set of recommendations on the diagnosis and management of heart failure in January 2006. Based on feedback obtained through a national program of heart failure workshops and through active solicitation of stakeholders, several topics were identified because of their importance to the practicing clinician. Topics chosen for the present update include best practices for the diagnosis and management of right-sided heart failure, myocarditis and device therapy, and a review of recent important or landmark clinical trials. These recommendations were developed using the structured approach for the review and assessment of evidence adopted and previously described by the Society. The present update has been written from a clinical perspective to provide a user-friendly and practical approach. Specific clinical questions that are addressed include: What is right-sided heart failure and how should one approach the diagnostic work-up? What other clinical entities may masquerade as this nebulous condition and how can we tell them apart? When should we be concerned about the presence of myocarditis and how quickly should patients with this condition be referred to an experienced centre? Among the myriad of recently published landmark clinical trials, which ones will impact our standards of clinical care? The goals are to aid physicians and other health care providers to optimally treat heart failure patients, resulting in a measurable impact on patient health and clinical outcomes in Canada.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia clinical presentation and diagnostic evaluation: results from the North American Multidisciplinary Study

BACKGROUND

Prior reports on patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) focused on individuals with advanced forms of the disease. Data on the diagnostic performance of various testing modalities in newly identified individuals suspected of having ARVC/D are limited.

OBJECTIVE

The purpose of the Multidisciplinary Study of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia was to study the clinical characteristics and diagnostic evaluation of a large group of patients newly identified with ARVC/D.

METHODS

A total of 108 newly diagnosed patients with suspected ARVC/D were prospectively enrolled in the United States and Canada. The patients underwent noninvasive and invasive tests using standardized protocols that initially were interpreted by the enrolling center and adjudicated by blind analysis in six core laboratories. Patients were followed for a mean of 27 +/- 16 months (range 0.2-63 months).

RESULTS

The clinical profile of these newly diagnosed patients differs from the profile of reported patients with more advanced disease. There was considerable difference in the initial and final classification of the presence of ARVC/D after the diagnostic tests were evaluated by the core laboratories. Final clinical diagnosis was 73 affected, 28 borderline, and 7 unaffected. Individual tests agreed with the final diagnosis in 50% to 70% of the 73 patients with a final classification of affected.

CONCLUSION

The clinical profile of 108 newly diagnosed probands with suspected ARVC/D indicates that a combination of diagnostic tests is needed to evaluate the presence of right ventricular structural, functional, and electrical abnormalities. Echocardiography, right ventricular angiography, signal-averaged ECG, and Holter monitoring provide optimal clinical evaluation of patients suspected of ARVC/D.

Left-dominant arrhythmogenic cardiomyopathy: an under-recognized clinical entity

OBJECTIVES

We sought to investigate the clinical-genetic profile of left-dominant arrhythmogenic cardiomyopathy (LDAC).

BACKGROUND

In the absence of coronary disease and left ventricular (LV) systolic dysfunction, lateral T-wave inversion and arrhythmia of LV origin are often considered benign. Similarly, chest pain with enzyme release might be attributed to viral myocarditis. We hypothesized that these abnormalities might be manifestations of the "left-dominant" subtype of arrhythmogenic right ventricular cardiomyopathy.

METHODS

The 42-patient cohort was established through clinical evaluation of individuals with unexplained (infero)lateral T-wave inversion, arrhythmia of LV origin, and/or proven LDAC/idiopathic myocardial fibrosis in the family.

RESULTS

Patients presented from adolescence to age >80 years with arrhythmia or chest pain but not heart failure. Desmosomal mutations were identified in 8 of 24 families (15 of 33 patients). Magnetic resonance findings included LV late-enhancement in a subepicardial/midwall distribution, corresponding to fibrofatty replacement and fibrosis on histopathology. Fifty percent had previously been misdiagnosed with viral myocarditis, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy, or idiopathic ventricular tachycardia. Arrhythmic events included presentation with ventricular fibrillatory arrest in 1 patient and 2 instances of sudden cardiac death during follow-up.

CONCLUSIONS

Arrhythmogenic cardiomyopathy is distinguished from DCM by a propensity towards arrhythmia exceeding the degree of ventricular dysfunction. The left-dominant subtype is under-recognized owing to misattribution to other disorders and lack of specific diagnostic criteria. Clinicians are alerted to the possibility of LDAC in patients of any age with unexplained arrhythmia of LV origin, (infero)lateral T-wave inversion, apparent DCM (with arrhythmic presentation), or myocarditis (chest pain and enzyme rise with unobstructed coronary arteries).

Anaesthetic implications of arrhythmogenic right ventricular dysplasia/cardiomyopathy

Arrhythmogenic right ventricular dysplasia, also called right ventricular cardiomyopathy, is a genetically determined heart muscle disease, characterised by life-threatening ventricular arrhythmias in apparently healthy young people. The primary myocardial pathology is that the myocardium of the right ventricular free wall is replaced by fibrous or fibrofatty tissue, with scattered residual myocardial cells. Right ventricular function is abnormal and in severe cases is associated with global right ventricular dilation and overt biventricular heart failure. Although still relatively rare, arrhythmogenic right ventricular cardiomyopathy is a well recognised cause of sudden unexpected peri-operative death. In this review, we describe the basic characteristics of this disease, emphasising the diagnosis and we offer some suggestions for the anaesthetic management of these patients in the peri-operative period.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: an update

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a genetic cardiomyopathy characterized by ventricular arrhythmias and structural abnormalities of the right ventricle (RV). The diagnosis is based on the International Task Force criteria. Cardiologists may not be aware of these diagnostic criteria for ARVC/D and may place too much importance on the results of MRI imaging of the right ventricle. Patients with ARVC/D usually have an abnormal 12-lead electrocardiogram, abnormal echocardiogram, and ventricular arrhythmias with a left bundle branch block morphology. If noninvasive testing suggests ARVC/D, invasive testing with an RV angiogram, RV biopsy, and electrophysiologic study is recommended. Once a diagnosis of ARVC/D is established, the main treatment decision involves whether to implant an implantable cardioverter-defibrillator. We also recommend treatment with beta blockers. Patients with ARVC/D are encouraged to avoid competitive athletics. Recent advances in the understanding of the genetic basis of ARVC/D have revealed that ARVC/D is a disease of desmosomal dysfunction.

Molecular genetics of sudden cardiac death

Sudden cardiac death (SCD) is one of the most common causes of death. An important number of sudden deaths, especially in the young, are due to genetic heart disorders, both with structural and arrhythmogenic abnormalities. In recent years, significant advances have been made in understanding the genetic basis of SCD. Identification of the genetic causes of sudden death is important because close relatives are also at potential risk of having a fatal cardiac condition. A comprehensive post-mortem investigation is vital to determine the cause and manner of death and provides the opportunity to assess the potential risk to the family after appropriate genetic counselling. In this paper, we present an update of the different genetic causes of sudden death, emphasizing their importance for the forensic pathologist due to his relevant role in the diagnosis and prevention of SCD.

Cardiac involvement in patients with Becker muscular dystrophy: new diagnostic and pathophysiological insights by a CMR approach

BACKGROUND

Becker-Kiener muscular dystrophy (BMD) represents an X-linked genetic disease associated with myocardial involvement potentially resulting in dilated cardiomyopathy (DCM). Early diagnosis of cardiac involvement may permit earlier institution of heart failure treatment and extend life span in these patients. Both echocardiography and nuclear imaging methods are capable of detecting later stages of cardiac involvement characterised by wall motion abnormalities. Cardiovascular magnetic resonance (CMR) has the potential to detect cardiac involvement by depicting early scar formation that may appear before onset of wall motion abnormalities.

METHODS

In a prospective two-center-study, 15 male patients with BMD (median age 37 years; range 11 years to 56 years) underwent comprehensive neurological and cardiac evaluations including physical examination, echocardiography and CMR. A 16-segment model was applied for evaluation of regional wall motion abnormalities (rWMA). The CMR study included late gadolinium enhancement (LGE) imaging with quantification of myocardial damage.

RESULTS

Abnormal echocardiographic results were found in eight of 15 (53.3%) patients with all of them demonstrating reduced left ventricular ejection fraction (LVEF) and rWMA. CMR revealed abnormal findings in 12 of 15 (80.0%) patients (p = 0.04) with 10 (66.6%) having reduced LVEF (p = 0.16) and 9 (64.3%) demonstrating rWMA (p = 0.38). Myocardial damage as assessed by LGE-imaging was detected in 11 of 15 (73.3%) patients with a median myocardial damage extent of 13.0% (range 0 to 38.0%), an age-related increase and a typical subepicardial distribution pattern in the inferolateral wall. Ten patients (66.7%) were in need of medical heart failure therapy based on CMR results. However, only 4 patients (26.7%) were already taking medication based on clinical criteria (p = 0.009).

CONCLUSION

Cardiac involvement in patients with BMD is underdiagnosed by echocardiographic methods resulting in undertreatment of heart failure. The degree and severity of cardiac involvement in this population is best characterised when state-of-the-art CMR methods are applied. Further studies need to demonstrate whether earlier diagnosis and institution of heart failure therapy will extend the life span of these patients.

Role of cardiac magnetic resonance imaging in assessment of nonischemic cardiomyopathies

Diagnosis of nonischemic cardiomyopathy is a challenging process that influences patient morbidity and mortality. Currently, the well known World Health Organization classification has been revisited by an American Heart Association expert consensus panel. The contemporary classification is compatible with the rapid evolution in molecular genetics and evolving diagnostic tools such as cardiac magnetic resonance imaging (MRI). Magnetic resonance imaging is a robust diagnostic tool that offers various techniques to assess the function, morphology, perfusion, and scarring of myocardial tissue thus providing better understanding of the underlying causes of nonischemic cardiomyopathies. In this review, we discuss the current role of cardiac MRI in the evaluation of nonischemic cardiomyopathy, in the context of the current American Heart Association classification of these disorders.

Recently defined cardiomyopathies: a clinician's update

Cardiomyopathy is a generic term for any heart disease in which the heart muscle is involved and functions abnormally. Recent developments and ongoing research in cardiology have led to descriptions of 3 previously less recognized or incompletely characterized cardiomyopathies. These entities are being increasingly noticed in adult patient populations. Primary care providers and cardiovascular specialists need to be aware of the clinical features of these illnesses and the best strategies for diagnosis and management. We have discussed the causes and diagnostic methods for these newly described cardiomyopathies and ways to manage them.

Left ventricular noncompaction and cardiomyopathy: cause, contributor, or epiphenomenon?

PURPOSE OF REVIEW

To discuss unresolved issues pertaining to aetiology and diagnosis of isolated left ventricular noncompaction.

RECENT FINDINGS

Left ventricular noncompaction may be sporadic or familial and is linked to mutations in mitochondrial, cytoskeletal, Z-line, and sarcomeric proteins. Severe childhood manifestations include fetal hydrops or sudden infant death syndrome. Adults with severe phenotypes have a similarly guarded prognosis due to heart failure, arrhythmia and thromboembolism. Conversely, healthy individuals may fulfil current imaging criteria for diagnosis. Left ventricular noncompaction is also observed in families with hypertrophic or dilated cardiomyopathy, casting doubt on its acceptance as a distinct disease entity.

SUMMARY

The extent of myocardial compaction may be a continuous trait within the population. Sensitive imaging techniques may detect subtle variations in morphology that fall within the normal range, underscoring the need for more restrictive diagnostic criteria, as in mitral valve prolapse. Conversely, rather than being a root cause of myocardial dysfunction, left ventricular noncompaction may represent a secondary consequence of a genetic alteration, well-tolerated when the heart is otherwise normal. In the presence of a pathogenic mutation, disruption to myocyte function at a molecular level may be the primary disease determinant, with noncompaction arising as a maladaptive remodelling response that compounds the disease process through subendocardial ischaemia and fibrosis.

The challenge of diagnosing arrhythmogenic right ventricular cardiomyopathy in the young

We report two cases of arrhythmogenic right ventricular cardiomyopathy (ARVC) in the pediatric age group. In both cases, the diagnosis was considered and pursued but would not be made utilizing Task Force Criteria. The diagnosis was made based on the morphology of a single beat during exercise testing. We illustrate the difficulty of diagnosing ARVC in the young even with a heightened index of suspicion.

Role of cardiovascular magnetic resonance imaging in arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a genetic cardiomyopathy characterized clinically by ventricular arrhythmias and progressive right ventricular (RV) dysfunction. The histopathologic hallmark is fibro-fatty replacement of RV myocardium. It is inherited in an autosomal pattern with variable penetrance. ARVD is unique in that it most commonly presents in young, otherwise healthy and highly athletic individuals. The cause of ARVD is not well-known but recent evidence suggests strongly that it is a disease of desmosomal dysfunction. The disease involvement is not limited only to the RV as left ventricle (LV) has also been reportedly affected. Diagnosis of ARVD is challenging and is currently based upon a multi-disciplinary work-up of the patient as defined by the Task Force. Currently, implanted cardioverter defibrillators (ICD) are routinely used to prevent sudden death in patients with ARVD. Cardiovascular MR is an important non-invasive diagnostic modality that allows both qualitative and quantitative evaluation of RV. This article reviews the genetics of ARVD, current status and role of CMR in the diagnosis of ARVD and LV involvement in ARVD.