Clinical profile of concealed form of arrhythmogenic right ventricular cardiomyopathy presenting with apparently idiopathic ventricular arrhythmias

Diagnosis and management of arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder of the myocardium that can lead to ventricular arrhythmia and sudden cardiac death. The condition has been identified as a significant cause of arrhythmic death among young people and athletes, therefore, early recognition of the disease by emergency clinicians is critical to prevent subsequent death. The diagnosis of ARVC can be very challenging and requires a systematic approach. This publication reviews the pathophysiology, classification, clinical presentations, and appropriate approach to diagnosis and management of ARVC.

Disease modeling of cardiac arrhythmias using human induced pluripotent stem cells

INTRODUCTION

Inherited arrhythmias are an uncommon, but malignant family of cardiac diseases that result from genetic abnormalities in the ion channels and/or structural proteins within cardiomyocytes. Given the inherent differences between species and the limited reproducibility of in vitro heterologous cell models, progress in understanding the mechanisms underlying these malignant diseases has always languished far behind the clinical science and need. The ability to study human induced pluripotent stem cells (iPSCs) derived cardiomyocytes promises to change this paradigm as patient cells have the potential to become testing platforms for disease phenotyping or therapeutic discovery.

AREAS COVERED

This review will outline methods developed to genetically reprogram adult cells into iPSCs, differentiate iPSCs into ex vivo models of adult cardiac tissue and iPSCs-based progress in exploring the mechanisms underlying pro-arrhythmic disease phenotypes.

EXPERT OPINION

Despite being discovered less than 15 years ago, several studies have successfully leveraged iPSCs-derived cardiomyocytes to study malignant arrhythmogenic diseases. These models promise to increase our understanding of the pathophysiology underlying these complex diseases and may identify personalized approaches to treatment.

Arrhythmogenic right ventricular cardiomyopathy with biventricular involvement and heart failure in a 9-year old girl

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is seldom recognized clinically in infancy or under the age of 10. We report a case of a 9-year-old girl with ARVC, who presented with signs and symptoms of heart failure and palpitations. Holter monitoring showed frequent premature ventricular beats and echocardiogram revealed dilated and dysfunctional right ventricle with normal tricuspid valve and no evidence of intracardiac shunt. Cardiac magnetic resonance showed classical features of ARVC with both ventricular involvements. After optimization of medical treatment the patient was referred for ICD implantation.

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC/D): A Systematic Literature Review

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a genetic form of cardiomyopathy (CM) usually transmitted with an autosomal dominant pattern. It primary affects the right ventricle (RV), but may involve the left ventricle (LV) and culminate in biventricular heart failure (HF), life threatening ventricular arrhythmias and sudden cardiac death (SCD). It accounts for 11%-22% of cases of SCD in the young athlete population. Pathologically is characterized by myocardial atrophy, fibrofatty replacement and chamber dilation. Diagnosis is often difficult due to the nonspecific nature of the disease and the broad spectrum of phenotypic variations. Therefore consensus diagnostic criteria have been developed and combined electrocardiography, echocardiography, cardiac magnetic resonance imaging (CMRI) and myocardial biopsy. Early detection, family screening and risk stratification are the cornerstones in the diagnostic evaluation. Implantable cardioverter-defibrillator (ICD) implantation, ablative procedures and heart transplantation are currently the main therapeutic options.

Arrhythmogenic right ventricular cardiomyopathy a still underrecognized clinic entity

Arrhythmogenic right ventricular cardiomyopathy is a new morbid entity that was discovered thanks to the study of sudden death in the young. This heart muscle disease is characterized by myocardial atrophy, mostly of the right ventricle, with massive fibro-fatty infiltration, accounting for ventricular electrical instability at risk of severe arrhythmias and even cardiac arrest. The disease was found to be the major cause of sudden death in young people and athletes in the Veneto Region, Italy. A familial occurrence with autosomal dominant transmission was then discovered, and the prevalence was estimated to be higher than 1 in 5000. The disease is genetically heterogeneous: Linkage analysis, carried out in a large family with recurrence of sudden deaths, led to map the gene to chromosome 14q23-q24. Linkage analysis in a second family allowed mapping of another gene to chromosome 1q42-q43. Clinical diagnosis can be achieved through electrocardiography, echocardiography, angiocardiography, magnetic resonance imaging, and endomyocardial biopsy. Diagnostic criteria have been put forward by a committee of the International Society and Federation of Cardiology. The disease was recently included among the cardiomyopathies in the revised World Health Organization (WHO) classification. Study of the natural history allowed us to distinguish (a) a covert phase in apparently normal subjects who have a risk of abrupt electrical instability and sudden death, (b) an overt arrhythmic phase with palpitations and impending cardiac arrest, (c) congestive heart failure with pump depression, sometimes so severe as to require heart transplantation. Both the etiology and pathogenesis of the disease are unknown. In particular, the mechanisms leading to progressive loss of myocardium and fibro-fatty replacement are still speculative. Apoptosis in the right ventricle occurring not only in infancy, as in the normal heart, but also in childhood and adulthood might account for the progressive disappearance of myocardial tissue. (Trends Cardiovasc Med 1997;7:84-90). © 1997, Elsevier Science Inc.

Correlation between the parameters of signal-averaged ECG and two-dimensional echocardiography in patients with arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

The correlation between parameters of two-dimensional echocardiography and signal-averaged ECG (SAECG) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) is not known well.

METHODS

Thirty-three patients (13 females, 40.3 +/- 14.4 years old) were included in this study. Both the right and left ventricular dimensions and systolic function were assessed with two-dimensional echocardiography. The SAECG was performed with high-gain amplification and filtered using bidirectional Butterworth filters between 40 and 250 Hz. We evaluated the correlation between the parameters of the SAECG and two-dimensional echocardiography.

RESULTS

The right ventricular (RV) outflow tract was the most frequently (n = 18, 54%) involved segment. Six (18%) patients had only mildly decreased RV systolic function. All the other patients had normal RV systolic function. Although localized left ventricular wall motion abnormalities were observed in 14 (42%) patients, the left ventricular ejection fraction was normal in most (n = 32, 97%). Late potentials were positive in 22 (63%) patients. There was no significant correlation between parameters of the SAECG and two-dimensional echocardiography for the entire patient population.

CONCLUSIONS

The SAECG parameters exhibited no correlation to any of two-dimensional echocardiography parameters in the patients with ARVC. Fragmented electrical activity may develop with no significant relation to the anatomical changes in the patients with ARVC.

Arrhythmogenic right ventricular cardiomyopathy: a survey of the investigations at the University of Padua

The purpose of this paper is to review the history of the clinico-pathologic investigations performed at the University of Padua on an old morbid entity ("parchment heart"), which, in the 1960s, led to the clinical description of the disease, in the 1980s to the revival of the scientific interest, and in the mid 1990s to the understanding of the genetic background. All the steps of the progressive knowledge are reviewed: necropsy of young people who died suddenly, in vivo diagnosis by ECG, echocardiography, angiocardiography, endomyocardial biopsy, nuclear magnetic resonance, and diagnostic criteria. Familial occurrence with autosomic dominant transmission and various penetrance was documented. Gene defects were recently mapped both to chromosome 14q23-q24 and 1q42-q43, thus providing evidence for genetic heterogeneity. The pathologic substrates of arrhythmogenic right ventricular cardiomyopathy pointed to an acquired progressive myocardial atrophy with fibro-fatty replacement of dying myocytes. Nowadays the disease is definitively regarded as a primary myocardial disorder and it has been included in the revised WHO classification of cardiomyopathies.

Idiopathic ventricular arrhythmias originating from the tricuspid annulus: Prevalence, electrocardiographic characteristics, and results of radiofrequency catheter ablation

BACKGROUND

Idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) arising from the tricuspid annulus have been reported.

OBJECTIVE

The purpose of this study was to clarify the prevalence and characteristics of VT/PVCs originating from the tricuspid annulus.

METHODS

The ECG characteristics and results of radiofrequency (RF) catheter ablation were analyzed in 454 patients with idiopathic VT/PVCs.

RESULTS

Thirty-eight (8%) patients had VT/PVCs arising from the tricuspid annulus: 28 VT/PVCs (74%) originated from the septal portion of the tricuspid annulus and the remaining 10 (26%) from the free wall of the tricuspid annulus. QRS duration and Q-wave amplitude in each of leads V1-V3 were greater in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (all P < .01). "Notching" of the QRS complex was observed more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .01). A Q wave in lead V1 was observed more often in VT/PVCs arising from the septum of the tricuspid annulus than those from the free wall of the tricuspid annulus (P < .005). R-wave transition occurred beyond lead V3 more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .005). RF catheter ablation eliminated 90% of the VT/PVCs arising from the free wall of the tricuspid annulus but only 57% of the VT/PVCs arising from septum of the tricuspid annulus.

CONCLUSION

Idiopathic VT/PVCs arising from tricuspid annulus are not rare, and the detailed origin can be determined by ECG analysis. The preferential site of origin was the septum but also could be the free wall of the tricuspid annulus.

Correlation of magnetic resonance imaging with histopathology in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an asymptomatic cardiac disease characterized by fatty infiltration of the right ventricular myocardium and often results in sudden cardiac death. ARVD/C diagnosis includes the assessment of fatty infiltration, which can be achieved noninvasively with cardiovascular magnetic resonance (CMR). The standard CMR protocol places the signal-generating coil directly on the anterior chest wall and produces a nonspecific high intensity signal that obscures the high signal from fatty infiltration. The aim of this study was to determine whether increasing the coil-to-chest distance would improve identification of fatty infiltration. Thoraces from seven embalmed cadavers were imaged on a conventional 1.5 Tesla CMR scanner using the control protocol and an experimental protocol, with a 6 cm coil-to-chest distance. A representative axial MR image and corresponding gross section of the heart were analyzed in each case. Fatty infiltration was graded in a blinded fashion on the MR images with independent histopathologic assessment. In five of the seven cases, the experimental protocol provided a correlation between CMR and histopathology that was as good as or better than the control protocol. The experimental protocol was also better in preventing false positive diagnosis in cases of minimal infiltration. Thus, the experimental protocol showed a stronger correlation with histopathology than did the control protocol. Increasing the distance between the anterior surface coil and chest wall may improve classification of presence or absence of fatty infiltration in the right ventricular myocardium, potentially improving the noninvasive detection of ARVD/C with CMR.

Ablation of Idiopathic Right Ventricular Outflow Tract Tachycardia: Current Perspectives

Ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) in the absence of overt structural heart disease is a common entity. Exclusion of occult structural disease such as arrhythmogenic right ventricular cardiomyopathy is critical as this diagnosis impacts both ablation outcomes and long-term prognosis. VT is most commonly due to triggered activity. Induction of the target arrhythmia in the laboratory is often problematic, and is frequently facilitated by catecholamine infusion. Recent data indicate that high-density three-dimensional activation mapping facilitates identification of target sites for ablation, and that the spatial resolution of pacemapping may be more limited than previously recognized. A standard 12-lead electrocardiogram is useful in providing an initial approximation of the site of origin within the outflow tract, and may contain subtle clues to potentially confounding foci on the left ventricular endocardial or epicardial surface. When sufficient arrhythmia is present to permit mapping, successful ablation can be expected in 90-95% of patients, with a recurrence risk of approximately 5%. In experienced centers, major complications are <or=1% and outcomes should approach those obtained for the common forms of supraventricular tachycardia.

Noninvasive detection of myocardial fibrosis in arrhythmogenic right ventricular cardiomyopathy using delayed-enhancement magnetic resonance imaging

OBJECTIVES

We evaluated the role of myocardial delayed-enhancement (MDE) magnetic resonance imaging (MRI) for noninvasive detection of fibrosis in Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).

BACKGROUND

Arrhythmogenic right ventricular dysplasia/cardiomyopathy is characterized by fibro-fatty replacement of the right ventricle (RV) leading to arrhythmias and RV failure. Endomyocardial biopsy can demonstrate fibro-fatty replacement of the RV myocardium; however, the test is invasive and carries a risk of perforation.

METHODS

Thirty consecutive patients were prospectively evaluated for ARVD/C. Magnetic resonance imaging was performed on a 1.5-T scanner. Ten minutes after intravenous administration of 0.2 mmol/kg of gadodiamide, MDE-MRI was obtained. Diagnosis of ARVD/C was based upon the Task Force criteria and did not include MRI findings.

RESULTS

Twelve (40%) of 30 patients met the Task Force criteria for ARVD/C. Eight (67%) of the 12 ARVD/C patients demonstrated increased signal on MDE-MRI in the RV compared with none (0%) of the 18 patients without ARVD/C (p <0.001). Endomyocardial biopsy was performed in 9 of the 12 ARVD/C patients. Of the nine patients, four had fibro-fatty changes consistent with the diagnosis of ARVD/C. Each of these patients had increased RV signal on MDE-MRI. None of the patients without ARVD/C had any abnormalities either on histopathology or on MDE-MRI. Electrophysiologic testing revealed inducible sustained ventricular tachycardia (VT) in six of the eight ARVD/C patients with delayed enhancement, compared with none of the ARVD/C patients without delayed enhancement (p=0.01).

CONCLUSIONS

Noninvasive detection of RV myocardial fibro-fatty changes in ARVD/C is possible by MDE-MRI. Magnetic resonance imaging findings had an excellent correlation with histopathology and predicted inducible VT on programmed electrical stimulation, suggesting a possible role in evaluation and diagnosis of patients with suspected ARVD/C.

Electrophysiological characteristics and outcome in patients with idiopathic right ventricular arrhythmia compared with arrhythmogenic right ventricular dysplasia

BACKGROUND

Idiopathic right ventricular arrhythmias (IRVA) are responsive to medical and ablative treatment and have a benign prognosis. Arrhythmias caused by right ventricular dysplasia (ARVD) are refractory to treatment and may cause sudden death. It is difficult to distinguish between these two types of arrhythmia.

OBJECTIVE

To differentiate patients with IRVA and ARVD by a conventional electrophysiological study.

METHODS

56 patients with a right ventricular arrhythmia were studied. They had no history or signs of any cardiac disease other than right ventricular dysplasia. They were classified as having IRVA (n = 41) or ARVD (n = 15) on the basis of family history, ECG characteristics, and various imaging techniques. They were further investigated by standard diagnostic electrophysiology.

RESULTS

The two groups were clearly distinguished by the electrophysiological study in the following ways: inducibility of ventricular tachycardia by programmed electrical stimulation with ventricular extrastimuli (IRVA 3% v ARVD 93%, p < 0.0001); presence of more than one ECG morphology during tachycardia (IRVA 0% v ARVD 73%, p < 0.0001); and fragmented diastolic potentials during ventricular arrhythmia (IRVA 0% v ARVD 93%, p < 0.0001). Data from the clinical follow up in these patients supported the diagnosis derived from the electrophysiological study.

CONCLUSIONS

Patients with IRVA or ARVD can be distinguished by specific electrophysiological criteria. A diagnosis of ARVD can be made reliably on the basis of clinical presentation, imaging techniques, and an electrophysiological study.

Arrhythmogenic right ventricular cardiomyopathy: current diagnostic and management strategies

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease of unknown etiology characterized by the peculiar right ventricular (RV) involvement. Distinctive pathologic features are myocardial atrophy and fibro-fatty replacement of the RV free wall, and clinical presentation is usually related to ventricular tachycardias with a left bundle branch block pattern or ventricular fibrillation leading to cardiac arrest, mostly in young people and athletes. Later in the disease evolution, progression and extension of RV muscle disease and left ventricular involvement may result in right or biventricular heart failure. The diagnosis of ARVC may be difficult because of several problems with specificity of ECG abnormalities, different potential etiologies of ventricular arrhythmias with a left bundle branch morphology, assessment of RV structure and function, and interpretation of endomyocardial biopsy findings. Therefore, standardized diagnostic criteria have been proposed by the Study Group on ARVC of the European Society of Cardiology. According to these guidelines, the diagnosis of ARVC is based on the presence of major and minor criteria encompassing electrocardiographic, arrhythmic, morphofunctional, histopathologic, and genetic factors. Since the assessment of sudden death risk in patients with ARVC is still not well established, there are no precise guidelines to determine which patients need to be treated and what is the best management approach. The therapeutic options include beta-blockers, antiarrhythmic drugs, catheter ablation, and implantable cardioverter defibrillator (ICD). The ICD is the most effective safeguard against arrhythmic sudden death. However, its precise role in changing the natural history of ARVC by preventing sudden and nonsudden death needs to be evaluated by a prospective study of a large series of patients. In patients in whom ARVC has progressed to severe RV or biventricular systolic dysfunction with risk of thromboembolic complications, treatment consists of current therapy for heart failure including anticoagulant therapy. In cases of refractory congestive heart failure, patients may become candidates for heart transplantation.

Clinical diagnosis and management strategies in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease, often familial, that is characterized by fibro-fatty replacement of the right ventricular (RV) myocardium. The most common clinical manifestations of ARVC consists of ventricular arrhythmias of RV origin, which may lead to sudden death mostly in young people and athletes, electrocardiograph depolarization/repolarization changes mostly localized to right precordial leads, and global and/or regional dysfunction and structural alterations of the RV. The diagnosis of ARVC may be difficult due to several problems with the specificity of the electrocardiograph abnormalities, the different potential etiologies of ventricular arrhythmias with a left bundle branch morphology, the assessment of the RV structure and function, and the interpretation of endomyocardial biopsy findings. Therefore, standardized diagnostic criteria have been proposed by the Study Group on ARVC of the European Society of Cardiology. According to these guidelines, the diagnosis of ARVC is based on the presence of major and minor criteria encompassing electrocardiograph, arrhythmic, morphofunctional, histopathologic, and genetic factors. Because the assessment of sudden death risk in patients with ARVC is still not well established, there are no precise guidelines to determine which are the patients who need to be treated and which is the best management approach. The therapeutic options include beta blockers, antiarrhythmic drugs, catheter ablation, and implantable cardioverter defibrillator. The implantable defibrillator is the most effective safe-guard against arrhythmic sudden death. However, its precise role in changing natural history of ARVC by preventing sudden and nonsudden death needs to be evaluated by a prospective study of a large series of patients. In patients in whom ARVC has progressed to severe RV or biventricular systolic dysfunction with risk of thromboembolic complications, treatment consists of current therapy for heart failure including anticoagulant therapy. In case of refractory congestive heart failure, the patients may become candidates for heart transplantation.

Clinical profile and long-term follow-up of 37 families with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVES

We sought to define the clinical picture and natural history of familial arrhythmogenic right ventricular cardiomyopathy (ARVC).

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy is a myocardial disease, often familial, clinically characterized by the impending risk of ventricular arrhythmias and sudden death.

METHODS

Thirty-seven ARVC families of northeast Italy were studied. Probands had a histologic diagnosis of ARVC, either at autopsy (19 families) or endomyocardial biopsy (18 families). Protocol of the investigation included basal electrocardiogram (ECG), 24-hour ECG, signal-averaged ECG, stress test and two-dimensional Doppler echocardiography. Invasive evaluation was performed when deemed necessary.

RESULTS

Of the 365 subjects, 151 (41%) were affected, 157 (43%) were unaffected, 17 (5%) were healthy carriers, and 40 (11%) were uncertain. Mean age at diagnosis was 31+/-13 years. By echocardiography, 64% had mild, 30% had moderate, and 6% had severe form. Forty percent had ventricular arrhythmias, 49 were treated with antiarrhythmic drugs, and two were treated with implantable cardioverter defibrillators. Sport activity was restricted in all. Of the 28 families who underwent linkage analysis, 6 mapped to chromosome 14q23-q24, 4 to 1q42-q43, and 4 to 2q32.1-q32.3. No linkage with known loci was found in four families and 10 had uninformative results. During a follow-up of 8.5+/-4.6 years, one patient died (0.08 patient/year mortality), and 15 developed an overt form of ARVC.

CONCLUSIONS

Arrhythmogenic right ventricular cardiomyopathy is a progressive disease appearing during adolescence and early adulthood. Systematic evaluation of family members leads to early identification of ARVC, characterized by a broad clinical spectrum with a favorable outcome. In the setting of positive family history, even minor ECG and echocardiographic abnormalities are diagnostic.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. European Society of Cardiology and the Scientific Council on Cardiomyopathies of the World Heart Federation

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disease characterized by peculiar right ventricular involvement and electrical instability that precipitates ventricular arrhythmias and sudden death. The purpose of the present consensus report of the Study Group of the European Society of Cardiology and the Scientific Council on Cardiomyopathies of the World Heart Federation is to review the considerable progress in our understanding of the etiopathogenesis, morbid anatomy, and clinical presentation of ARVD/C since its first description in 1977. This article will focus on the important but still unanswered issues, mostly regarding risk stratification, clinical outcome, and management of affected patients. Because ARVD/C is relatively uncommon and any one center may have experience with only a few patients, an international registry is being established to accumulate information and enhance the numbers of patients that can be analyzed to answer the pending questions. The registry also will facilitate pathologic, molecular, and genetics research on the etiology and pathogenesis of the disease. Furthermore, availability of an international database will enhance awareness of this largely unrecognized condition among the medical community. Physicians are encouraged to enroll patients in the International Registry of ARVD/C.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. Study Group on Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy of the Working Groups on Myocardial and Pericardial Disease and Arrhythmias of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the World Heart Federation

Arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disease characterized by peculiar RV involvement and electrical instability that precipitates ventricular arrhythmias and sudden death. The purpose of the present consensus report of the Study Group on ARVD/C of the Working Groups on Myocardial and Pericardial Disease and Arrhythmias of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the World Heart Federation is to review the considerable progress in our understanding of the etiopathogenesis, morbid anatomy, and clinical presentation of ARVD/C since it first was described in 1977. The present article focuses on important but still unanswered issues, mostly regarding risk stratification, clinical outcome, and management of affected patients. Because ARVD/C is relatively uncommon and any one center may have experience with only a few patients, an international registry is being established to accumulate information and enhance the numbers of patients that can be analyzed and thus answer pending questions. The registry also will facilitate pathological, molecular, and genetics research on the causes and pathogenesis of the ARVD/C. Furthermore, availability of an international database will enhance awareness of this largely unrecognized condition among the medical community. Physicians are encouraged to enroll patients in the International Registry of ARVD/C.

Familial effort polymorphic ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy map to chromosome 1q42-43

In the present study we report on another cause of an arrhythmia associated with familial arrhythmogenic right ventricular cardiomyopathy (ARVC), which is linked to chromosome 1q42-43. Two families with 48 subjects were studied with 12-lead electrocardiography, 24-hour ambulatory electrocardiography, chest x-ray, M-mode and 2-dimensional echocardiography, signal-averaging electrocardiography, and exercise stress testing. Six subjects also underwent right and left ventricular angiography and electrophysiologic study. An endomyocardial biopsy was performed in 1 subject. The genetic study included pedigree reconstruction and linkage analysis with polymorphic DNA markers. Five young subjects died suddenly during exercise; autopsy was performed in 3 and showed segmental fibro-fatty replacement of the right ventricle, mostly at the apex. Two of them experienced syncopal attacks during effort. Sixteen living subjects, without arrhythmias at rest had polymorphic ventricular arrhythmias during effort; ARVC was diagnosed in 15, whereas 1 did not have any demonstrable cardiac abnormality. The remaining family members were healthy and did not have arrhythmias. The linkage study assigned the disease locus to chromosome 1q42-q43, in close proximity to the alpha-actinin 2 locus (maximal lod score was 5.754 at theta = 0) with a 95% penetrance. Thus, these data suggest that effort-induced polymorphic ventricular arrhythmias and juvenile sudden death can be due to adrenergic stimulation in a particular genetic group of ARVC patients. In these cases the pathology was segmental, mostly localized to the right ventricular apex. Ventricular arrhythmias that are present in these families differ from the monomorphic ones that are usually seen in patients with ARVC.

Gene for arrhythmogenic right ventricular cardiomyopathy with diffuse nonepidermolytic palmoplantar keratoderma and woolly hair (Naxos disease) maps to 17q21

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease of unknown etiology that causes arrhythmias, heart failure, and sudden death. Diagnosis can be difficult, and this hampers investigation of its molecular basis. Forms of ARVC in which gene penetrance and disease expression are greater should facilitate genetic study. We undertook a clinical and genetic investigation of Naxos disease, originally described by Protonotarios in 1986. This disease constitutes the triad of ARVC, diffuse nonepidermolytic palmoplantar keratoderma, and woolly hair.

METHODS AND RESULTS

We evaluated the population of Naxos, Greece, to identify probands, which was followed by family screening. Twenty-one affected persons from 9 families of 150 persons were identified. Linkage analysis was performed with microsatellite markers. The disease locus mapped to 17q21. A peak 2-point LOD score of 3.62 at theta=0.0 was found with a marker within intron 4 of the keratin 9 gene, a member of the type I (acidic) keratin family. A preserved homozygous disease haplotype was identified. Haplotype analysis delimited the disease interval.

CONCLUSIONS

Hair and skin abnormalities were found to be reliable markers of subsequent heart disease. This suggests the presence of a single mutant gene with novel cardiac, skin, and hair function or two or more tightly linked disease genes. Recessive inheritance of Naxos disease and a founder effect were demonstrated. Identification of a fully informative genetic marker linked to the disease and uncommon in the background population may be of use as a test to identify disease gene carriers.

Electrocardiographic and morphometric features in patients with ventricular tachycardia of right ventricular origin

OBJECTIVE

To study differences between repetitive monomorphic ventricular tachycardia (RMVT) of right ventricular origin, and ventricular tachycardia in arrhythmogenic right ventricular dysplasia (ARVD).

PATIENTS

Consecutive groups with RMVT (n = 15) or ARVD (n = 12), comparable for age and function.

METHODS

Analysis of baseline, tachycardia, and signal averaged ECGs, clinical data, and right endomyocardial biopsies. Pathological findings were related to regional depolarisation (QRS width) and repolarisation (QT interval, QT dispersion).

RESULTS

There was no difference in age, ejection fraction, QRS width in leads I, V1, and V6, and QT indices. During ventricular tachycardia, more patients with ARVD had a QS wave in V1 (p < 0.05). There were significant differences for unfiltered QRS, filtered QRS, low amplitude signal duration, and the root mean square voltage content. In the absence of bundle branch block, differences became non-significant for unfiltered and filtered QRS duration. Mean (SD) percentage of biopsy surface differed between RMVT and ARVD: normal myocytes (74(3.4)% v 64.5(9.3)%; p < 0.05); fibrosis (3(1.7)% v 8.9(5.2)%; p < 0.05). When all patients were included, there were significant correlations between fibrosis and age (r = 0.6761), and fibrosis and QRS width (r = 0.5524 for lead I; r = 0.5254 for lead V1; and r = 0.6017 for lead V6).

CONCLUSIONS

The ECG during tachycardia and signal averaging are helpful in discriminating between ARVD and RMVT patients. There are differences in the proportions of normal myocytes and fibrosis. The QRS duration is correlated with the amount of fibrous tissue in patients with ventricular tachycardia of right ventricular origin.

Arrhythmogenic right ventricular dysplasia as a cause of sudden death

Arrhythmogenic right ventricular dysplasia (ARVD) is a poorly understood and often underdiagnosed disorder of the right ventricle, characterized by replacement of myocardium by fibroadipose tissue, arrhythmic manifestations, and sudden death. The disease occurs in families and is inherited as an autosomal dominant trait. This report describes five cases of ARVD identified by autopsy. In three of the cases, sudden death occurred in the young (16-28 years old) during or shortly after exercise. In another case, a 46-year-old man with no relevant medical history was found dead in his bathroom. In the last case, a 57-year-old woman died from pulmonary thromboembolism. In none of the subjects had the disease been diagnosed or suspected before death. Only one (a 21-year-old man) had previous typical symptoms of the disease. Autopsy examination showed right ventricle dilation and, in four cases, cardiomegaly. The right ventricular myocardium of all hearts was almost replaced by adipose tissue and to a variable degree by fibrous tissue, while the left ventricle myocardium demonstrated no, or only scattered, fibro-fatty infiltration. Postmortem diagnosis of ARVD can be important in identifying possible affected family members in order to initiate treatment.

Spectrum of clinicopathologic manifestations of arrhythmogenic right ventricular cardiomyopathy/dysplasia: a multicenter study

OBJECTIVES

The aim of the present investigation was to redefine the clinicopathologic profile of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC), with special reference to disease progression and left ventricular (LV) involvement.

BACKGROUND

Long-term follow-up data from clinical studies indicate that ARVC is a progressive heart muscle disease that with time may lead to more diffuse right ventricular (RV) involvement and LV abnormalities and culminate in heart failure.

METHODS

Forty-two patients (27 male, 15 female; 9 to 65 years old, mean [+/-SD] age 29.6 +/- 18) from six collaborative medical centers, with a pathologic diagnosis of ARVC at autopsy or heart transplantation, and with the whole heart available, were studied according to a specific clinicomorphologic protocol.

RESULTS

Thirty-four patients died suddenly (16 during effort); 4 underwent heart transplantation; 2 died as a result of advanced heart failure; and 2 died of other causes. Sudden death was the first sign of disease in 12 patients; the other 30 had palpitations, with syncope in 11, heart failure in 8 and stroke in 3. Twenty-seven patients experienced ventricular arrhythmias (ventricular tachycardia in 17), and 5 received a pacemaker. Ten patients had isolated RV involvement (group A); the remaining 32 (76%) also had fibrofatty LV involvement that was observed histologically only in 15 (group B) and histologically and macroscopically in 17 (group C). Patients in group C were significantly older than those in groups A and B (39 +/- 15 years vs. 20 +/- 8.8 and 25 +/- 9.7 years, respectively), had significantly longer clinical follow-up (9.3 +/- 7.3 years vs. 1.2 +/- 2.1 and 3.4 +/- 2.2 years, respectively) and developed heart failure significantly more often (47% vs. 0 and 0, respectively). Patients in groups B and C had warning symptoms (80% and 87%, respectively, vs. 30%) and clinical ventricular arrhythmias (73% and 82%, respectively, vs. 20%) significantly more often than patients in group A. Hearts from patients in group C weighed significantly more than those from patients in groups A and B (500 +/- 150 g vs. 328 +/- 40 and 380 +/- 95 g, respectively), whereas hearts from both group B and C patients had severe RV thinning (87% and 71%, respectively, vs. 20%) and inflammatory infiltrates (73% and 88%, respectively, vs. 30%) significantly more often than those from group A patients.

CONCLUSIONS

LV involvement was found in 76% of hearts with ARVC, was age dependent and was associated with clinical arrhythmic events, more severe cardiomegaly, inflammatory infiltrates and heart failure. ARVC can no longer be regarded as an isolated disease of the right ventricle.

Arrhythmogenic right ventricular cardiomyopathy. Dysplasia, dystrophy, or myocarditis?

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a frequent cause of sudden death in young individuals and athletes. Although familial occurrence has been documented and a gene defect was recently localized on chromosome 14q23-q24 the etiopathogenesis of the disease is still obscure.

METHODS AND RESULTS

A pathological study was conducted in 30 hearts with ARVC (age range, 15 to 65 years; mean, 28 years). In the 27 autopsy cases, the mode of death was sudden in 24 and congestive heart failure in 3. ECG, available in 19 cases, showed inverted T waves in the right precordial leads in 15 cases (79%) and ventricular arrhythmias in 15 (79%). Right ventricular aneurysms were present in 15 hearts (50%) and located in the inferior wall in 12. Left ventricle and ventricular septum were involved in 14 (47%) and 6 (20%) cases, respectively. Scattered foci of lymphocytes with myocardial death were observed in 20 cases (67%). Electron microscopy studies, although confirming the myocardial death and lymphocyte infiltrates, did not show any specific ultrastructural substrate. Two pathological patterns, fatty (40%) and fibrofatty (60%), were identified. The fibrofatty pattern was associated with a thinner right ventricular wall (P < .0001) and a higher occurrence of focal myocarditis (P < .001). In sections of right ventricular free wall with maximal fatty infiltration, the mean percentage area of fatty tissue was 35.9 +/- 11.1% in control versus 80.4 +/- 9.6% in the ARVC, fatty variety (P < .00001). Involvement of the left ventricle and/or ventricular septum, right ventricular aneurysms, and inflammation were found almost exclusively in the fibrofatty variety.

CONCLUSIONS

In the fibrofatty variety of ARVC, the myocardial atrophy appears to be the consequence of acquired injury (myocyte death) and repair (fibrofatty replacement), mediated by patchy myocarditis. Whether the inflammation is a primary event or a reaction to spontaneous cell death remains unclear.

Signal-averaged electrocardiography in familial form of arrhythmogenic right ventricular cardiomyopathy

This study was performed to establish whether signal-averaged electrocardiography can aid in the diagnosis of the familial form of arrhythmogenic right ventricular cardiomyopathy in order to determine the severity of the disease and to predict ventricular arrhythmias. In arrhythmogenic right ventricular cardiomyopathy there is a fatty fibrous substitution of myocardium, which is the substrate for delayed myocardial activation; this is responsible for the abnormalities seen on the signal-averaged electrocardiogram (SAECG). Seventy-five members of 11 families, both healthy and with various forms of the disease, were studied using a signal-averaged electrocardiographic technique. Forty-seven members, 16 with a severe and 31 with a minor form of the disease, were found to be affected. Forty-three subjects had abnormal results on the SAECG; of these, 39 had the disease (100% in patients with widespread disease and 74.1% in patients with a minor form), whereas the other 4 had no sign of the disease. Only 44.1% of the subjects with an abnormal SAECG had ventricular arrhythmias, whereas 76% of the subjects with ventricular arrhythmias had an abnormal SAECG. In contrast, 90.6% of patients with an abnormal SAECG had the disease, and only subjects with arrhythmogenic right ventricular cardiomyopathy had ventricular arrhythmias. The abnormality on the SAECG appears to be correlated with the severity of the disease. Signal-averaged electrocardiography does not seem useful in diagnosing the minor forms of the disease and it does not give precise information about electrical instability in these patients.

Arrhythmogenic right ventricular cardiomyopathy in young versus adult patients: similarities and differences

OBJECTIVES

This study was designed to evaluate and compare the patterns of arrhythmogenic right ventricular cardiomyopathy in young people and adults.

BACKGROUND

Few data are available on this cardiomyopathy in young people because clinical and morphologic findings considered pathognomonic are normally based on observations in adults. However, a familial occurrence with a probable genetic transmission led to the study of children and to early detection of this disease, in which sudden death has been reported even in young people.

METHODS

Seventeen young patients with arrhythmogenic right ventricular cardiomyopathy diagnosed at a mean age +/- SD of 14.9 +/- 4.9 years were studied. Clinical, electrocardiographic, echocardiographic, cineangiographic and biopsy findings were compared with those of 19 adult patients whose condition was diagnosed at a mean age of 38.1 +/- 13.4 years.

RESULTS

Syncope occurred in 23.5% of the young patients but in none of the adults (odds ratio of familial sudden death 5.54, p = 0.1). Ventricular couplets (odds ratio 16.0, p = 0.004) and subtricuspid bulging on echocardiography (odds ratio 5.95, p = 0.036) were prevalent in the young group. Cineangiographic data in the two groups were similar, except that more hypokinetic areas were found in adults (odds ratio 4.44, p = 0.05). Morphometric analysis of biopsy sections showed a greater amount of fibrous tissue in the young patients (p = 0.04) and a prevalence of fatty tissue in the adults (odds ratio 12, p = 0.005). During an equivalent follow-up time (mean 7 years), two young patients died suddenly, and two had ventricular fibrillation in the absence of antiarrhythmic therapy.

CONCLUSIONS

The pathognomonic criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy in adults are also valid for young people. Sudden or aborted death occurred frequently in young untreated patients.

Regional myocardial sympathetic dysinnervation in arrhythmogenic right ventricular cardiomyopathy. An analysis using 123I-meta-iodobenzylguanidine scintigraphy

BACKGROUND

In patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), the frequent provocation of ventricular tachycardia during exercise, the sensitivity toward catecholamines, and the response toward antiarrhythmic drug regimen with antiadrenergic properties suggest an involvement of the sympathetic nervous system in arrhythmogenesis.

METHODS AND RESULTS

To analyze the presence, extent, and location of impaired myocardial sympathetic innervation in ARVC, 123I-meta-iodobenzylguanidine (123I-MIBG) scintigraphy was performed in 48 patients with ARVC. For comparison, 9 patients with idiopathic ventricular tachycardia and a control group of 7 patients without heart disease were investigated. In patients with ARVC, the clinical sustained (n = 25; 52%) or nonsustained (n = 23; 48%) ventricular tachycardia originated in the right ventricular outflow tract in 38 patients (79%), whereas in the remaining 10 patients (21%), the site of origin was the apical (n = 5) or inferior (n = 5) right ventricle. In 33 patients (69%), nonsustained or sustained ventricular tachycardia was provocable by exercise (n = 28 of 48; 58%) and/or by isoproterenol infusion (n = 16 of 37; 43%), whereas programmed ventricular stimulation induced sustained or nonsustained ventricular tachycardia in 16 patients each (33% each). With 123I-MIBG scintigraphy, the right ventricle was not visible in any patient. No areas of intense 123I-MIBG uptake ("hot spots") were observed. All patients of the control group and 7 of 9 patients (78%) with idiopathic ventricular tachycardia showed a uniform tracer uptake in the left ventricle. In contrast, only 8 of 48 ARVC patients (17%) showed a homogeneous distribution of 123I-MIBG uptake, whereas 40 patients (83%) demonstrated regional reductions or defects of tracer uptake. In 3 of 48 patients (6%), the defect area was < 15%; in 21 patients (44%), it was 15% to 30%; and in 16 patients (33%), it was > 30% of the polar map area of the left ventricle (mean, 23 +/- 15%; range, 0% to 57%). In 38 of 40 patients (95%) with an abnormal 123I-MIBG scan, reduced tracer uptake was located in the basal posteroseptal left ventricle, involving the adjacent lateral wall in 10, the anterior wall in 2, and the apex in 12 patients. Only 2 patients demonstrated isolated defects of the anterior or lateral wall; one involved the apex. Perfusion abnormalities in the areas of 123I-MIBG defects were excluded by stress/redistribution 201T1 single-photon emission computed tomography scintigraphy and by normal coronary angiograms in all patients. Abnormalities in 123I-MIBG scintigraphy in patients with ARVC correlated with the site of origin of ventricular tachycardia, demonstrating a regionally reduced tracer uptake in 36 of 38 patients (95%) with right ventricular outflow tract tachycardia compared with only 4 of 10 patients (40%) with other right ventricular origins of tachycardia. There was no correlation between the results of 123I-MIBG scintigraphy and the extent of right ventricular contraction abnormalities, right ventricular ejection fraction, biopsy results, coronary anatomy, or left ventricular involvement in ARVC.

CONCLUSIONS

In patients with ARVC, regional abnormalities of sympathetic innervation are frequent and can be demonstrated by 123I-MIBG scintigraphy. Sympathetic denervation appears to be the underlying mechanism of reduced 123I-MIBG uptake and may be related to frequent provocation of ventricular arrhythmias by exercise or catecholamine exposure in ARVC. Therefore, in patients with ARVC, the noninvasive detection of localized sympathetic denervation by 123I-MIBG imaging may have implications for the early diagnosis and for the choice of antiarrhythmic drugs in the treatment of arrhythmias.

Spectrum of right heart involvement in patients with ventricular tachycardia unrelated to coronary artery disease or left ventricular dysfunction

We studied 41 patients with clinically symptomatic ventricular tachycardia in the absence of coronary artery disease or left ventricular dysfunction to define the extent of right and left heart derangement and their relation to electrophysiologic and clinical data. Individual echocardiographic measurements as well as global assessment scores of the right and left heart demonstrated a wide spectrum of right heart echocardiographic abnormalities. There was much less variation in the left heart, with the majority of patients being close to normal. There was an association between the right heart score, the clinical presentation of arrhythmia, the response to programmed electrical stimulation, and the recurrence of arrhythmia (p < 0.05). Thus echocardiographic findings demonstrate the whole spectrum of right heart involvement in patients with apparent idiopathic ventricular tachycardia and can give insight into clinical history, arrhythmia inducibility, and prognosis.

Determinants of inducible ventricular tachycardia in patients with clinical ventricular tachyarrhythmia and no apparent structural heart disease

Thirty-seven patients with symptomatic ventricular tachyarrhythmia and no apparent structural heart disease were evaluated with multiple cardiovascular tests to establish the relationship between the results of programmed electric stimulation and other clinical and arrhythmia variables. Of 37 patients, 12 (32%) had inducible sustained ventricular tachycardia. Factors associated with the results of programmed electric stimulation included a history of ventricular tachycardia > or = 30 seconds requiring intervention for termination and global right heart abnormality documented by echocardiography. During treatment for a mean follow-up of 50 months, 29 patients did well, 6 patients had recurrences of major arrhythmia symptoms, 1 was lost to follow-up and 1 had a noncardiac death. Those patients with an adverse outcome were more likely to have inducible ventricular tachycardia. Thus certain clinical and echocardiographic data are associated with the results of programmed electric stimulation, which in turn have important prognostic value in this group of patients. Sustained ventricular tachycardia is unlikely to be induced in patients with no evidence of structural heart disease and clinical nonsustained ventricular tachycardia.

Dysplastic conditions of the right ventricular myocardium: Uhl's anomaly vs arrhythmogenic right ventricular dysplasia

OBJECTIVE

Since 1905 there have been many reports of cases in which the right ventricle was deficient in myocardium. Several terms have been used to describe this condition. Of these, "Uhl's anomaly" and "arrhythmogenic right ventricular dysplasia" are most often used. Our study investigates the relation between these entities.

METHOD

Five cases with a primary deficiency of the right ventricular musculature were examined. The findings were compared with those published reports to evaluate the similarities and differences between Uhl's anomaly and arrhythmogenic dysplasia.

RESULTS

The five cases showed two patterns of myocardial deficiency in the right ventricle. On the one hand, the parietal wall was paper thin with complete absence of musculature and apposition of the endocardial and epicardial layers. On the other hand, patchy, localised fibrofatty tissue replacement was found within the parietal musculature. Evidence from our cases, combined with analysis of other publications, showed different modes and timing of clinical presentation of the patients with these two anatomical conditions, congestive heart failure or arrhythmia.

CONCLUSIONS

The conditions variously described as Uhl's anomaly and arrhythmogenic dysplasia are separate and distinct morphological entities.