Distribution of biventricular disease in arrhythmogenic cardiomyopathy: an autopsy study

The Many Faces of Arrhythmogenic Cardiomyopathy: An Overview

Arrhythmogenic cardiomyopathy (AC) is a disease that involves electromechanical uncoupling of cardiomyocytes. This leads to characteristic histologic changes that ultimately lead to the arrhythmogenic clinical features of the disease. Initially thought to affect the right ventricle predominantly, more recent data show that it can affect both the ventricles or the left ventricle alone. Throughout the recent era, diagnostic modalities and criteria for AC have continued to evolve and our understanding of its clinical features in different age groups as well as the genotype to the phenotype correlations have improved. In this review, we set out to detail the epidemiology, etiologies, presentations, evaluation, and management of AC across the age continuum.

DSP-Related Cardiomyopathy as a Distinct Clinical Entity? Emerging Evidence from an Italian Cohort

Variants in desmoplakin gene (DSP MIM *125647) have been usually associated with Arrhythmogenic Cardiomyopathy (ACM), or Dilated Cardiomyopathy (DCM) inherited in an autosomal dominant manner. A cohort of 18 probands, characterized as heterozygotes for DSP variants by a target Next Generation Sequencing (NGS) cardiomyopathy panel, was analyzed. Cardiological, genetic data, and imaging features were retrospectively collected. A total of 16 DSP heterozygous pathogenic or likely pathogenic variants were identified, 75% (n = 12) truncating variants, n = 2 missense variants, n = 1 splicing variant, and n = 1 duplication variant. The mean age at diagnosis was 40.61 years (IQR 31-47.25), 61% of patients being asymptomatic (n = 11, New York Heart Association (NYHA) class I) and 39% mildly symptomatic (n = 7, NYHA class II). Notably, 39% of patients (n = 7) presented with a clinical history of presumed myocarditis episodes, characterized by chest pain, myocardial enzyme release, 12-lead electrocardiogram abnormalities with normal coronary arteries, which were recurrent in 57% of cases (n = 4). About half of the patients (55%, n = 10) presented with a varied degree of left ventricular enlargement (LVE), four showing biventricular involvement. Eleven patients (61%) underwent implantable cardioverter defibrillator (ICD) implantation, with a mean age of 46.81 years (IQR 36.00-64.00). Cardiac magnetic resonance imaging (CMRI) identified in all 18 patients a delayed enhancement (DE) area consistent with left ventricular (LV) myocardial fibrosis, with a larger localization and extent in patients presenting with recurrent episodes of myocardial injury. These clinical and genetic data confirm that DSP-related cardiomyopathy may represent a distinct clinical entity characterized by a high arrhythmic burden, variable degrees of LVE, Late Gadolinium Enhancement (LGE) with subepicardial distribution and episodes of myocarditis-like picture.

Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) encompasses a group of conditions characterized by right ventricular fibrofatty infiltration, with a predominant arrhythmic presentation. First described in the late 1970s and early 1980s, it is now frequently recognized to have biventricular involvement. The prevalence is ∼1:2,000 to 1:5,000, depending on geographic location, and it has a slight male predominance. The diagnosis of ARVC is determined on the basis of fulfillment of task force criteria incorporating electrophysiological parameters, cardiac imaging findings, genetic factors, and histopathologic features. Risk stratification of patients with ARVC aims to identify those who are at increased risk of sudden cardiac death or sustained ventricular tachycardia. Factors including age, sex, electrophysiological features, and cardiac imaging investigations all contribute to risk stratification. The current management of ARVC includes exercise restriction, β-blocker therapy, consideration for implantable cardioverter-defibrillator insertion, and catheter ablation. This review summarizes our current understanding of ARVC and provides clinicians with a practical approach to diagnosis and management.

Contribution of concomitant myocarditis to the development of various clinical types of arrhythmogenic right ventricular cardiomyopathy

Aim. To assess the contribution of genetic and inflammatory factors to the development of arrhythmogenic right ventricular cardiomyopathy (ARVC).

Material and methods. The study involved 54 patients with ARVC (age, 38,7±14,1 years; men, 42,6%; mean follow-up period, 21 [6; 60] months). All patients underwent electrocardiography (ECG), 24-hour ECG monitoring, echocardiography, determination of anticardiac antibodies and DNA of cardiotropic viruses in the blood, molecular genetic ARVC testing, as well as cardiac magnetic resonance imaging (n=49), high-resolution ECG (n=18), right ventricular endomyocardial biopsy (n=2), and autopsy (n=2).

Results. Following four clinical types of ARVC were identified: I. Latent arrhythmic form: characterized by frequent premature ventricular contractions and/or nonsustained ventricular tachycardia (VT). II. Manifested arrhythmic form (n=11) — SVT/ventricular fibrillation (VF). III. ARVC with progressive heart failure (HF, n=8). IV. Combination of ARVC with left ventricular noncompaction (LVNC, n=8). Superimposed myocarditis was identified in 74%, 36%, 87,5% and 85,7% of patients in forms I-IV, respectively. Mutations were detected in 11%, 46%, 50%, and 38% of patients in forms I-IV, respectively. Clinical forms were stable: there was no transition from one clinical form to another during follow-up period.

Conclusion. The contribution of genetic and inflammatory mechanisms to the clinical picture is different: in the latent arrhythmic form, the leading role belongs to inflammation; in the manifested arrhythmic form, the contribution of pathogenic mutations prevails, and in ARVC with progressive HF and in combination with LVNC, the contribution of genetic and inflammatory factors is equally important.

Left ventricular fibro-fatty replacement in arrhythmogenic right ventricular dysplasia/cardiomyopathy: prevalence, patterns, and association with arrhythmias

BACKGROUND

Left ventricular (LV) fibrofatty infiltration in arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) has been reported, however, detailed cardiovascular magnetic resonance (CMR) characteristics and association with outcomes are uncertain. We aim to describe LV findings on CMR in ARVD/C patients and their relationship with arrhythmic outcomes.

METHODS

CMR of 73 subjects with ARVD/C according to the 2010 Task Force Criteria (TFC) were analyzed for LV involvement, defined as ≥ 1 of the following features: LV wall motion abnormality, LV late gadolinium enhancement (LGE), LV fat infiltration, or LV ejection fraction (LVEF) < 50%. Ventricular volumes and function, regional wall motion abnormalities, and the presence of ventricular fat or fibrosis were recorded. Findings on CMR were correlated with arrhythmic outcomes.

RESULTS

Of the 73 subjects, 50.7% had CMR evidence for LV involvement. Proband status and advanced RV dysfunction were independently associated with LV abnormalities. The most common pattern of LV involvement was focal fatty infiltration in the sub-epicardium of the apicolateral LV with a "bite-like" pattern. LGE in the LV was found in the same distribution and most often had a linear appearance. LV involvement was more common with non-PKP2 genetic mutation variants, regardless of proband status. Only RV structural disease on CMR (HR 3.47, 95% CI 1.13-10.70) and prior arrhythmia (HR 2.85, 95% CI 1.33-6.10) were independently associated with arrhythmic events.

CONCLUSION

Among patients with 2010 TFC for ARVD/C, CMR evidence for LV abnormalities are seen in half of patients and typically manifest as fibrofatty infiltration in the subepicardium of the apicolateral wall and are not associated with arrhythmic outcomes.

A 3D high resolution MRI method for the visualization of cardiac fibro-fatty infiltrations

Modifications of the myocardial architecture can cause abnormal electrical activity of the heart. Fibro-fatty infiltrations have been implicated in various cardiac pathologies associated with arrhythmias and sudden cardiac death, such as arrhythmogenic right ventricular cardiomyopathy (ARVC). Here, we report the development of an MRI protocol to observe these modifications at 9.4 T. Two fixed ex vivo human hearts, one healthy and one ARVC, were imaged with an Iterative decomposition with echo asymmetry and least-square estimations (IDEAL) and a magnetization transfer (MT) 3D sequences. The resulting fat fraction and MT ratio (MTR) were analyzed and compared to histological analysis of the three regions (“ARVC triangle”) primarily involved in ARVC structural remodeling. In the ARVC heart, high fat content was observed in the “ARVC triangle” and the superimposition of the MTR and fat fraction allowed the identification of fibrotic regions in areas without the presence of fat. The healthy heart exhibited twice less fat than the ARVC heart (31.9%, 28.7% and 1.3% of fat in the same regions, respectively). Localization of fat and fibrosis were confirmed by means of histology. This non-destructive approach allows the investigation of structural remodeling in human pathologies where fibrosis and/or fatty tissue infiltrations are expected to occur.

Arrhythmogenic Cardiomyopathy: Molecular Insights for Improved Therapeutic Design

Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder characterized by structural and electrical cardiac abnormalities, including myocardial fibro-fatty replacement. Its pathological ventricular substrate predisposes subjects to an increased risk of sudden cardiac death (SCD). ACM is a notorious cause of SCD in young athletes, and exercise has been documented to accelerate its progression. Although the genetic culprits are not exclusively limited to the intercalated disc, the majority of ACM-linked variants reside within desmosomal genes and are transmitted via Mendelian inheritance patterns; however, penetrance is highly variable. Its natural history features an initial “concealed phase” that results in patients being vulnerable to malignant arrhythmias prior to the onset of structural changes. Lack of effective therapies that target its pathophysiology renders management of patients challenging due to its progressive nature, and has highlighted a critical need to improve our understanding of its underlying mechanistic basis. In vitro and in vivo studies have begun to unravel the molecular consequences associated with disease causing variants, including altered Wnt/β-catenin signaling. Characterization of ACM mouse models has facilitated the evaluation of new therapeutic approaches. Improved molecular insight into the condition promises to usher in novel forms of therapy that will lead to improved care at the clinical bedside.

Phenotypic expression of ARVC: How 12 lead ECG can predict left or right ventricle involvement. A familiar case series and a review of literature

AIMS

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart-muscle disease primarily affecting the right ventricle (RV) and potentially causing sudden death in young people. The natural history of the disease is firstly characterized by a concealed form progressing over a biventricular involvement. Three different cases coming from the same family are presented together with a review of the literature.

METHODS AND RESULTS

Multi-parameter analysis including imaging and electrocardiographic analysis is presented since the first medical referral with follow-up ranging from 11 to 38years. Case 1 presented a typical RV involvement in agreement with the ECG pattern. Case 2 presented a prevalent left ventricular involvement leading from the beginning to a pattern of dilated cardiomyopathy in agreement with his ECG evolution over the years. On the other side, Case 3 came to observation with a typical RV involvement (similar to Case 1) but with ECG evolution of typical left ventricle involvement (similar to Case 2). The genetic analysis showed a mutation in desmoglein-2 (DSG2) gene: p. Arg49His. Comparison between size and localization of ventricular dyskinesia at cardiovascular imaging and the surface 12 lead electrocardiography are proposed.

CONCLUSIONS

ARVC may lead to an extreme phenotypic variability in clinical manifestations even within patients coming from the same family in which ARVC is caused by the same genetic mutation. ECG progression over time reflects disease evolution and in particular cases may anticipate wall motion abnormalities by years.

Nonischemic left ventricular scar and cardiac sudden death in the young

Nonischemic left ventricular scar (NLVS) is a pattern of myocardial injury characterized by midventricular and/or subepicardial gadolinium hyperenhancement at cardiac magnetic resonance, in absence of significant coronary artery disease. We aimed to evaluate the prevalence of NLVS in juvenile sudden cardiac death and to ascertain its etiology at autopsy. We examined 281 consecutive cases of sudden death of subjects aged 1 to 35 years. NLVS was defined as a thin, gray rim of subepicardial and/or midmyocardial scar in the left ventricular free wall and/or the septum, in absence of significant stenosis of coronary arteries. NLVS was the most frequent finding (25%) in sudden deaths occurring during sports. Myocardial scar was localized most frequently within the left ventricular posterior wall and affected the subepicardial myocardium, often extending to the midventricular layer. On histology, it consisted of fibrous or fibroadipose tissue. Right ventricular involvement was always present. Patchy lymphocytic infiltrates were frequent. Genetic and molecular analyses clarified the etiology of NLVS in a subset of cases. Electrocardiographic (ECG) recordings were available in more than half of subjects. The most frequent abnormality was the presence of low QRS voltages (<0.5 mV) in limb leads. In serial ECG tracings, the decrease in QRS voltages appeared, in some way, progressive. NLVS is the most frequent morphologic substrate of juvenile cardiac sudden death in sports. It can be suspected based on ECG findings. Autopsy study and clinical screening of family members are required to differentiate between arrhythmogenic right ventricular cardiomyopathy/dysplasia and chronic acquired myocarditis.

Mutations of desmoglein-2 in sudden death from arrhythmogenic right ventricular cardiomyopathy and sudden unexplained death

Desmoglein-2 (DSG2), a member of the desmosomal cadherin superfamily, has been linked to arrhythmogenic right ventricular cardiomyopathy (ARVC)which may cause life-threatening ventricular arrhythmias and sudden death. Fatal arrhythmias resulting in sudden death also occur in the absence of morphologic cardiac abnormalities at autopsy. We sequenced all 15 exons of DSG2 in DNA extracted from post-mortem heart tissues of 25 patients dying with ARVC and 25 from sudden unexplained death (SUD). The primers were designed using the Primer Express 3.0 software. Direct sequencing for both sense and antisense strands was performed with a BigDye Terminator DNA sequencing kit on a 3130 xl Genetic Analyzer. Mutation damage prediction was made using Mutation Taster, Polyphen and SIFT software. 2 DSG2 mutations (p. S1026Q fsX12, p. G678R)in two ARVC samples and 2 DSG2 mutations(p. E 896K, p. A858 V) in two SUD samples were identified, all the mutations were novel. We concluded that DSG2 mutations may not specific for ARVC and may be related to the fatal arrhythmic events even in patients with a morphological normal heart.

[Arrhythomgenic right ventricular dysplasia and sudden death: An autopsy and histological study]

Arrhythmogenic right ventricular dysplasia (ARVD) is cardiomyopathy where normal myocardial tissue is replaced with fibrofatty tissue. Histological examination performed on myocardial biopsy or on autopsy samples are used to confirm the diagnosis. However, in many cases, the diagnosis cannot be made on a simple macroscopic and histological study and requires genetic analysis and molecular biology. In this work, we propose to describe the main macroscopic and histological findings of ARVD through the study of an autopsy series. We report 12 autopsy cases of sudden death in ARVD collected in the Department of Forensic Medicine of the University Hospital Fattouma Bourguiba Monastir (Tunisia) during a period of 20years. Microscopic examination was performed on 5microns thick histological sections. All slides were reviewed by two operators in a double blind (physician pathologist, pathologist) and in each, the percentage of adipose tissue, fibrosis and infarction in the right ventricle, left ventricle and interventricular septum, the presence or absence of inflammatory infiltrate, the presence or absence of signs of degeneration of myocytes were noticed. ARVD was found in 12 cases (1.8% of sudden cardiac death). The age ranged between 13 and 67years (mean age: 45.3years). The death occurred in half of the cases during exercise. Macroscopic examination of the RV showed the presence of a wall thinning (thickness<3mm) in 9 cases. Histological study highlight RV adipose infiltration in all cases with a percentage between 15% and 60%, fibrotic lesions were observed in only 9 cases with an average percentage of 10.25% and signs of degeneration of myocytes were noted in 10 cases. In concordance with what has been reported in the literature, there is still no consensus regarding the criteria to be adopted to pose with certainty the diagnosis of ARVD and the presence of adipose tissue remains the criterion more suggestive.

Left ventricular involvement in arrhythmogenic right ventricular cardiomyopathy - a cardiac magnetic resonance imaging study

BACKGROUND

Few studies evaluated left ventricular (LV) involvement in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). The aim of this study is to determine the frequency, clinical presentation, and pattern of LV involvement in ARVD/C (LV-ARVD/C).

METHODS

We retrospectively evaluated the cardiac magnetic resonance (CMR) in 202 patients referred between 2008 and 2012 to our institution, and we determined the presence or the absence of CMR criteria in the revised task force criteria 2010 for the diagnosis of ARVD/C. A total of 21 patients were diagnosed with ARVD/C according to the revised task force criteria 2010. All included patients had no previous history of myocarditis, acute coronary syndrome, or any other cardiac disease that could interfere with the interpretations of structural abnormalities. The LV involvement in ARVD/C was defined by the presence of one or more of the following criteria: LV end-diastolic volume (LVEDV; >95 mL/m²), LV ejection fraction (LVEF; <55%), LV late enhancement of gadolinium (LVLE) in a non-ischemic pattern, and LV wall motion abnormalities (WMAs). In the follow-up for the occurrence of cardiac death, ventricular tachycardia (VT) was obtained at a mean of 31 ± 20.6 months.

RESULTS

A total of 21 patients had ARVD/C. The median age was 48 (33–63) years. In all, 11 patients (52.4%) had LV-ARVD/C. The demographic characteristics of patients with or without LV were similar. There was a higher frequency of left bundle-branch block (LBBB) VT morphology in ARVD/C (P = 0.04). In CMR, regional WMAs of right ventricle (RV) and RV ejection fraction (RVEF; <45%) were strongly correlated with LV-WMAs (r = 0.72, P = 0.02, r = 0.75, P = 0.02, respectively). RV late enhancement of gadolinium (RVLE) was associated with LV-WMs and LVLE (r = 0.7, P = 0.03; r = 0.8, P = 0.006). LVLE was associated with LV-WMAs, LVEF, and LVEDV (r = 0.9, P = 0.001; r = 0.8, P = 0.001; r = 0.8, P = 0.01).

CONCLUSION

LV involvement in ARVD/C is common and frequently associated with moderate to severe right ventricular (RV) abnormalities. The impact of LV involvement in ARVD/C on the prognosis needs further investigations.

Is cardiac MRI an effective test for arrhythmogenic right ventricular cardiomyopathy diagnosis?

AIM: To evaluate the referrals with suspected arrhythmogenic right ventricular cardiomyopathy (ARVC) and compare cardiac MR (cMR) findings against clinical diagnosis.

METHODS: A retrospective analysis of 114 (age range 16 to 83, males 55% and females 45%) patients referred for cMR with a suspected diagnosis of ARVC between May 2006 and February 2010 was performed after obtaining institutional approval for service evaluation. Reasons for referral including clinical symptoms and family history of sudden death, electrocardiogram and echo abnormalities, cMR findings, final clinical diagnosis and information about clinical management were obtained. The results of cMR were classified as major, minor, non-specific or negative depending on both functional and tissue characterisation and the cMR results were compared against the final clinical diagnosis.

RESULTS: The most common reasons for referral included arrhythmias (30%) and a family history of sudden death (20%). Of the total cohort of 114 patients: 4 patients (4%) had major cMR findings for ARVC, 13 patients (11%) had minor cMR findings, 2 patients had non-specific cMR findings relating to the right ventricle and 95 patients had a negative cMR. Of the 4 patients who had major cMR findings, 3 (75%) had a positive clinical diagnosis. In contrast, of the 13 patients who had minor cMR findings, only 2 (15%) had a positive clinical diagnosis. Out of the 95 negative patients, clinical details were available for 81 patients and none of them had ARVC. Excluding the 14 patients with no clinical data and final diagnosis, the sensitivity of the test was 100%, specificity 87%, positive predictive value 29% and the negative predictive value 100%.

CONCLUSION: CMR is a useful tool for ARVC evaluation because of the high negative predictive value as the outcome has a significant impact on the clinical decision-making.

Recognizing life-threatening causes of syncope

While the overall prognosis of syncope is favorable, the identification of individuals with a potentially life-threatening cause is of paramount importance. Cardiac syncope is associated with an elevated risk of mortality, and includes both primary arrhythmic and obstructive etiologies. Identification of these individuals is contingent on careful clinical assessment and judicious use of diagnostic investigations. This article focuses on life-threatening causes of syncope and a diagnostic approach to facilitate their identification.

Quantitative Immunohistochemistry of Desmosomal Proteins (Plakoglobin, Desmoplakin and Plakophilin), Connexin-43, and N-cadherin in Arrhythmogenic Cardiomyopathy: An Autopsy Study

Background:

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder related to mutations in desmosomal proteins. The current study tests the hypothesis that immunohistochemical staining for desmosomal proteins is of diagnostic utility by studying autopsy-confirmed cases of ARVC.

Methods and Results:

We studied 23 hearts from patients dying suddenly with ARVC. Control subject tissues were 21 hearts from people dying from non-cardiac causes (n=15), dilated cardiomyopathy (n=3) and coronary artery disease (n=3).

Areas free of fibrofatty change or scarring were assessed on 50 sections from ARVC (24 left ventricle, 26 right ventricle) and 28 sections from controls. Immunohistochemical stains against plakoglobin, plakophilin, desmoplakin, connexin-43, and N-cadherin were applied and area expression analyzed by computerized morphometry. Desmin was stained as a control for fixation and similarly analyzed.

The mean area of desmin expression was similar in controls and ARVC (86% vs. 85%, p=0.6). Plakoglobin expression was 4.9% ± 0.3% in controls, vs. 4.6% ± 0.3% in ARVC (p=0.3). Plakophilin staining was 4.8% ± 0.3% in controls vs. 4.4% ± 03% in ARVC (p=0.3). Desmoplakin staining was 3.4% in controls vs. 3.2 ± 0.2% in ARVC (p=0.6). There were no significant differences when staining was compared between right and left ventricles (all p > 0.1).

For non-desmosomal proteins, the mean area of connexin-43 staining showed no significant difference by presence of disease.

Conclusions:

The small and insignificant decrease in junction protein expression in ARVC suggests that immunohistochemistry is not a useful tool for the diagnosis.

In vitro functional analyses of arrhythmogenic right ventricular cardiomyopathy-associated desmoglein-2-missense variations

Background

Although numerous sequence variants in desmoglein-2 (DSG2) have been associated with arrhythmogenic right ventricular cardiomyopathy (ARVC), the functional impact of new sequence variations is difficult to estimate.

Methodology/Principal Findings

To test the functional consequences of DSG2-variants, we established an expression system for the extracellular domain and the full-length DSG2 using the human cell line HT1080. We established new tools to investigate ARVC-associated DSG2 variations and compared wild-type proteins and proteins with one of the five selected variations (DSG2-p.R46Q, -p.D154E, -p.D187G, -p.K294E, -p.V392I) with respect to prodomain cleavage, adhesion properties and cellular localisation.

Conclusions/Significance

The ARVC-associated DSG2-p.R46Q variation was predicted to be probably damaging by bioinformatics tools and to concern a conserved proprotein convertase cleavage site. In this study an impaired prodomain cleavage and an influence on the DSG2-properties could be demonstrated for the R46Q-variant leading to the classification of the variant as a potential gain-of-function mutant. In contrast, the variants DSG2-p.K294E and -p.V392I, which have an arguable impact on ARVC pathogenesis and are predicted to be benign, did not show functional differences to the wild-type protein in our study. Notably, the variants DSG2-p.D154E and -p.D187G, which were predicted to be damaging by bioinformatics tools, had no detectable effects on the DSG2 protein properties in our study.

A case of arrhythmogenic right ventricular cardiomyopathy without arrhythmias

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by recurrent coma, ventricular tachycardias and the replacement of the myocardium with fatty and fibrous tissue. We described a 42-year-old female patient without clinical arrhythmias which was diagnosed as ARVC by magnetic resonance imaging (MRI), but the transvenous endomyocardial biopsy was not specific. The patient received heart transplantation due to her refractory heart failure and the pathology of explanted heart demonstrated typical replacement of fatty and fibrous tissue and piles of infiltrated lymphocytes in myocardial tissue. It is concluded that ARVC might not have any arrhythmias and inflammatory process may be involved in the mechanism of ARVC. Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/6573514507145351.