Arrythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) and cathecholaminergic polymorphic ventricular tachycardia (CPVT): A phenotypic spectrum seen in same patient.

ARVD/C and CPVT are rare inheritable sudden cardiac death syndromes predominantly expressed in younger individuals. ARVD/C is characterized by a progressive fibrofatty replacement of the myocardium that predisposes to ventricular tachycardia while CPVT is characterized by exercise induced bidirectional/polymorphic ventricular tachycardia (VT) and a structurally normal heart. A mutation in different genes causes these syndromes but recently, mutation in a common gene RYR2 has been associated with both disorders and it has been suggested that CPVT and ARVD/C represent a phenotypic spectrum. We present a case unique in expressing both these phenotypes.

The use of fontaine leads in the diagnosis of arrhythmogenic right ventricular dysplasia.

We report a case of a 68-year-old man admitted to the emergency department with syncope preceded by rapid palpitations. His admission ECG demonstrated a sustained ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT). This report highlights the importance of distinguishing ventricular tachycardia caused by arrhythmogenic right ventricular dysplasia (ARVD) from the more benign idiopathic RVOT-VT. Furthermore, we demonstrate the utility of the Fontaine leads placement in increasing the sensitivity for uncovering epsilon waves, a highly specific electrocardiographic feature that increases diagnostic accuracy in patients with ARVD.

A Novel Homozygous PKP2 Variant in Severe Neonatal Non-compaction and Concomitant Ventricular Septal Defect: A Case Report.

Left ventricular non-compaction (LVNC) is a rare and genetically heterogeneous cardiomyopathy. The disorder vastly affects infants and young children. Severe neonatal LVNC is relatively rare. The prevalence of genetic defects underlying pediatric and adult-onset LVNC is about 17-40%. Mutations of MYH7 and MYBPC3 sarcomeric genes are found in the vast majority of the positive pediatric cases. PKP2 encodes plakophilin-2, a non-sarcomeric desmosomal protein, which has multiple roles in cardiac myocytes including cell-cell adhesion, tightening gap junction, and transcriptional factor. Most of the reported PKP2 mutations are heterozygous missense and truncating variants, and they are associated with an adult-onset autosomal dominant disorder, namely arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). Homozygous PKP2 mutations have been rarely described. Herein, we present a rare case of an infant with neonatal onset of congestive heart failure owing to severe LVNC and multiple muscular VSD. Medical treatments failed to control the heart failure and the patient died at 11 months of age. Whole-exome sequencing identified a novel homozygous PKP2 variant, c.1511-1G>C, in the patient. An mRNA analysis revealed aberrant transcript lacking exon 7, which was predicted to cause a frameshift and truncated peptide (p.Gly460GlufsTer2). The heterozygous parents had normal cardiac structures and functions as demonstrated by electrocardiogram and echocardiography. Pathogenic variants of sarcomeric genes analyzed were not found in the patient. We conducted a literature review and identified eight families with biallelic PKP2 mutations. We observed that three families (our included) with null variants were linked to lethal phenotypes, while homozygous missense mutations resulted in less severe manifestations: adolescent-onset ARVD/C and childhood-onset DCM. Our data support a previous notion that severe neonatal LVNC might represent a unique entity and had distinct genetic spectrum. In conclusion, the present study has extended the phenotypes and genotypes of PKP2-related disorders and lethal LVNC.

Uhl's Anomaly With Left Ventricular Noncompaction: Role of Multimodality Imaging in a Rare Association.

Uhl's anomaly is a rare congenital heart disease characterized by partial or complete absence of the right ventricle myocardium. We report the first case, in a 21-year-old man, of Uhl's anomaly-associated left ventricular noncompaction. This association represents a unique clinical entity and has important implications for management strategies. (Level of Difficulty: Intermediate.).

Clinical picture of arrhythmogenic right ventricular dysplasia / cardiomyopathy patients from Indian origin.

OBJECTIVE: Among the inherited cardiomyopathies, Arrhythmogenic right ventricular dysplasia/cardiomyopathy is unique with a peculiar pathology of fibro-fatty replacement. Studies have been carried out all over the world and several groups have reported clinical heterogeneity in manifestation of ARVD/C related symptoms. Present study is an attempt to identify the clinical profile of ARVD/C patients from Asian Indian origin. METHODS: 31 patients in the span of three years were diagnosed with ARVD/C. Diagnosis was based on proposed task force criteria. RESULTS: The mean age at diagnosis was 32.9 +/- 16.4 years with slight tilt in male to female ratio (1.46). About 80% cases had palpitations, syncope in 45.16% and dyspnea in 22.5%, whereas 16% of patients were asymptomatic. About 50% of patients revealed a family history of confirmed ARVD/C or sudden death of a family member without any known cause. ECG showed T-wave inversion in about 60% cases, prolongation of QRS was observed in 20% cases. RV dilatation was observed in 80% of patients and 66.7% showed systolic dysfunction. RV free wall motion abnormalities were found in 33% patients. Most of the early onset cases with less than 30 years of age showed family history indicative of ARVD/C. Familial study in three patients indicated early onset of condition in younger generations in two families. CONCLUSIONS: ARVD/C in India shows relatively early age at onset when compared with other Asian populations with more than half of patients showing the disease below the age of 30 years. History in most of the early onset cases revealed family history indicating strong genetic influence.

The Prognostic Value of Right Ventricular Deformation Imaging in Early Arrhythmogenic Right Ventricular Cardiomyopathy.

OBJECTIVES: The aim of this study was to investigate the prognostic value of echocardiographic deformation imaging in arrhythmogenic right ventricular cardiomyopathy (ARVC) to optimize family screening protocols. BACKGROUND: ARVC is characterized by variable disease expressivity among family members, which complicates family screening protocols. Previous reports have shown that echocardiographic deformation imaging detects abnormal right ventricular (RV) deformation in the absence of established disease expression in ARVC. METHODS: First-degree relatives of patients with ARVC were evaluated according to 2010 task force criteria, including RV deformation imaging (n = 128). Relatives fulfilling structural task force criteria were excluded for further analysis. At baseline, deformation patterns of the subtricuspid region were scored as type I (normal deformation), type II (delayed onset, decreased systolic peak, and post-systolic shortening), or type III (systolic stretching and large post-systolic shortening). The final study population comprised relatives who underwent a second evaluation during follow-up. Disease progression was defined as the development of a new 2010 task force criterion during follow-up that was absent at baseline. RESULTS: Sixty-five relatives underwent a second evaluation after a mean follow-up period of 3.7 ± 2.1 years. At baseline, 28 relatives (43%) had normal deformation (type I), and 37 relatives (57%) had abnormal deformation (type II or III) in the subtricuspid region. Disease progression occurred in 4% of the relatives with normal deformation at baseline and in 43% of the relatives with abnormal deformation at baseline (p < 0.001). Positive and negative predictive values of abnormal deformation were, respectively, 43% (95% confidence interval: 27% to 61%) and 96% (95% confidence interval: 82% to 100%). CONCLUSIONS: Normal RV deformation in the subtricuspid region is associated with absence of disease progression during nearly 4-year follow-up in relatives of patients with ARVC. Abnormal RV deformation seems to precede the established signs of ARVC. RV deformation imaging may potentially play an important role in ARVC family screening protocols.

Exercise-related sudden cardiac death of an American football player with arrhythmogenic right ventricular dysplasia/cardiomyopathy AND sarcoidosis.

This case emphasizes the value of cardiac MRI and genetic testing in the early phase of ARVD/C. It also emphasizes the increased risk of SCD for patients with ARVD/C participating in competitive sports, even with immediate cardiopulmonary resuscitation.

The application of signal average ECG in the prediction of recurrences after catheter ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy.

BACKGROUND: The changes of signal averaged ECG (SAECG) in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) undergoing radiofrequency catheter ablation (RFCA) of ventricular arrhythmias (VAs) remains unknown. METHODS: Between 2010 and 2014, a total of 81 ARVD/C patients underwent endocardial and/or epicardial RFCA for drug-refractory VAs. Seventy patients (mean age 46.2±14.1years, 37 males) achieving acute procedure success (negative inducibility) were enrolled. Baseline characteristics, non-invasive examinations and SAECG (before and 3months after RFCA) were collected retrospectively. RESULTS: After successful RFCA, the electrical parameters of SAECG changed in 39 patients (55.7%), including 28 patients (40%) with electrical regression (group 1), and 11 patients (15.7%) with electrical progression (group 3). Thirty-one patients (44.3%) showed no significant SAECG change (group 2). During a mean follow-up of 17.8±10.7months, 23 patients (32.9%) had VA recurrences, including 4 in group 1, 12 in group 2, and 7 in group 3. In comparisons with groups 2 and 3, group 1 patients had a significantly better VA recurrence-free survival (P=0.02). In multivariable Cox regression analysis, electrical regression was found to be associated with fewer VA recurrences (P=0.02, OR: 0.28, 95% CI: 0.10-0.83). CONCLUSIONS: Electrical regression of SAECG after RFCA in ARVD/C was found to be associated with fewer VA recurrences.

Clinical Genetic Testing for the Cardiomyopathies and Arrhythmias: A Systematic Framework for Establishing Clinical Validity and Addressing Genotypic and Phenotypic Heterogeneity.

Advances in DNA sequencing have made large, diagnostic gene panels affordable and efficient. Broad adoption of such panels has begun to deliver on the promises of personalized medicine, but has also brought new challenges such as the presence of unexpected results, or results of uncertain clinical significance. Genetic analysis of inherited cardiac conditions is particularly challenging due to the extensive genetic heterogeneity underlying cardiac phenotypes, and the overlapping, variable, and incompletely penetrant nature of their clinical presentations. The design of effective diagnostic tests and the effective use of the results depend on a clear understanding of the relationship between each gene and each considered condition. To address these issues, we developed simple, systematic approaches to three fundamental challenges: (1) evaluating the strength of the evidence suggesting that a particular condition is caused by pathogenic variants in a particular gene, (2) evaluating whether unusual genotype/phenotype observations represent a plausible expansion of clinical phenotype associated with a gene, and (3) establishing a molecular diagnostic strategy to capture overlapping clinical presentations. These approaches focus on the systematic evaluation of the pathogenicity of variants identified in clinically affected individuals, and the natural history of disease in those individuals. Here, we applied these approaches to the evaluation of more than 100 genes reported to be associated with inherited cardiomyopathies and arrhythmias including hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular dysplasia or cardiomyopathy, long QT syndrome, short QT syndrome, Brugada, and catecholaminergic polymorphic ventricular tachycardia, and to a set of related syndromes such as Noonan Syndrome and Fabry disease. These approaches provide a framework for delivering meaningful and accurate genetic test results to individuals with hereditary cardiac conditions.

Recent advances in genetic testing and counseling for inherited arrhythmias.

Inherited arrhythmias, such as cardiomyopathies and cardiac ion channelopathies, along with coronary heart disease (CHD) are three most common disorders that predispose adults to sudden cardiac death. In the last three decades, causal genes in inherited arrhythmias have been successfully identified. At the same time, it has become evident that the genetic architectures are more complex than previously known. Recent advancements in DNA sequencing technology (next generation sequencing) have enabled us to study such complex genetic traits. This article discusses indications for genetic testing of patients with inherited arrhythmias. Further, it describes the benefits and challenges that we face in the era of next generation sequencing. Finally, it briefly discusses genetic counseling, in which a multidisciplinary approach is required due to the increased complexity of the genetic information related to inherited arrhythmias.

Left Ventricular Involvement in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Assessed by Echocardiography Predicts Adverse Clinical Outcome.

BACKGROUND: Among studies describing the phenotype of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), significant discrepancy exists regarding the extent and impact of left ventricular (LV) involvement. The capability of conventional and new quantitative echocardiographic techniques to accurately detect LV involvement in ARVD/C remains unknown. The aim of this study was to test the hypothesis that accurate detection of LV involvement on echocardiography identifies patients at additional risk for cardiac events during follow-up. METHODS: Thirty-eight patients with ARVD/C, 16 pathogenic mutation-positive relatives, and 55 healthy control subjects were prospectively enrolled. Conventional echocardiography with additional deformation imaging was performed in all subjects to detect LV involvement. In a subgroup (n = 27), cardiac magnetic resonance imaging was performed with late enhancement. All patients and relatives were prospectively followed for events (sustained ventricular tachycardia, appropriate implantable cardioverter-defibrillator intervention, sudden cardiac death, and heart transplantation). RESULTS: Conventional echocardiography detected LV involvement in 32% of patients with ARVD/C and in none of the relatives. Deformation imaging revealed LV involvement in 68% of patients with ARVD/C and 25% of relatives and was correlated closely with late enhancement on cardiac magnetic resonance imaging. During a mean follow-up period of 5.9 ± 2.3 years, 20 patients with ARVD/C (53%) experienced events, and no events occurred in the relatives. LV involvement detected by deformation imaging (hazard ratio, 4.9; 95% CI, 1.7-14.2) and right ventricular outflow tract enlargement (hazard ratio, 1.2; 95% CI, 1.1-1.3) were the only independent predictors of outcomes. CONCLUSIONS: Deformation imaging detected a high incidence of LV involvement in patients with ARVD/C and their relatives. Compared with conventional echocardiography, deformation imaging is superior in detecting minor LV involvement. LV involvement and an enlarged right ventricular outflow tract are independent prognostic markers of outcomes.

Statistical evaluation of reproducibility of automated ECG measurements: an example from arrhythmogenic right ventricular dysplasia/cardiomyopathy clinic.

BACKGROUND: Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is characterized by delay in depolarization of the right ventricle, detected by prolonged terminal activation duration (TAD) in V1-V3. However, manual ECG measurements have shown moderate-to-low intra- and inter-reader agreement. The goal of this study was to assess reproducibility of automated ECG measurements in the right precordial leads. METHODS: Pairs of ECGs recorded in the same day from Johns Hopkins ARVD/C Registry participants [n=247, mean age 35.2±15.6 y, 58% men, 92% whites, 11(4.5%) with definite ARVD/C] were retrospectively analyzed. QRS duration, intrinsicoid deflection, TAD, and T-wave amplitude in the right precordial leads, as well as averaged across all leads QRS duration, QRS axis, T axis, QTc interval, and heart rate was measured automatically, using 12SL TM algorithm (GE Healthcare, Wauwatosa, WI, USA). Intrinsicoid deflection was measured as the time from QRS complex onset to the alignment point of the QRS complex. TAD was calculated as the difference between QRS duration and intrinsicoid in V1, V2, V3. Reproducibility was quantified by Bland-Altman analysis (bias with 95% limits of agreement), Lin's concordance coefficient, and Bradley-Blackwood procedure. RESULTS: Bland-Altman analysis revealed satisfactory reproducibility of tested parameters. V1 QRS duration bias was -0.10ms [95% limits of agreement -12.77 to 12.56ms], V2 QRS duration bias -0.09ms [-11.13 to 10.96ms]; V1 TAD bias 0.14ms [-13.23 to 13.51ms], V2 TAD bias 0.008ms [-12.42 to 12.44ms]. CONCLUSION: Comprehensive statistical evaluation of reproducibility of automated ECG measurements is important for appropriate interpretation of ECG. Automated ECG measurements are reproducible to within 25%.

Clinico-radiological profile of arrhythmogenic right ventricular dysplasia at a tertiary care center: Two year experience.

BACKGROUND: Arrythmogenic right ventricular dysplasia (ARVD/C) refers to fibro fatty infiltration replacement of ventricular myocardium especially that of right ventricle. The clinical presentation varies from asymptomatic state to ventricular tachycardia, heart failure and even sudden death. Diagnosis is established using modified ARVD/C taskforce criteria. Among all the various modalities of diagnosis, magnetic resonance imaging (MRI) gives most comprehensive evaluation of both morphological and functional abnormalities in this disease. MRI may not only obviate need for myocardial biopsy but also give insights into the nature of disease like presence of left ventricular myocardial involvement. We present our 2 years experience of ARVD/C patents who were admitted in our center and in whom diagnosis of ARVD/C was supported by excellent MR imaging. MATERIALS AND METHODS: This study was conducted by Department of Radiology and Cardiology SKIMS, a tertiary care center for a period of 2 years. Patients with suspected ARVD/C based on clinical, electrophysiological and echocardiographic findings were subjected to MR imaging. Patients were excluded if they had history metallic implants, claustrophobia or were uncooperative. In this study stress was laid on diagnostic role of MRI in ARVD/C. RESULTS: The median age at presentation was 31 years (range 21-43 years). 80% of patients were males. Most common clinical presentation was palpatations (40%). Syncope was present in 27% and heart failure in 13%. EKG suggestive of ARVD was seen in 87%. Echocardiographic features suggestive of ARVD/C was seen in all 15 patients. Family history of premature sudden death less than 35 years old was present in one patient only. MRI evidence classical for ARVD/C was seen in 80%. CONCLUSION: Demographic features and mode of presentation of our patients is consistent with what has been rest of the world. We performed MRI in all patients to increase the specificity of our diagnosis. MR imaging allows a three-dimensional evaluation of the right ventricle and provides the most important anatomic, functional, and morphologic criteria for diagnosis of ARVD/C within one single study. MR imaging appears to be the optimal imaging technique for detection and follow-up of clinically suspected ARVD/C.

Incremental value of cardiac magnetic resonance imaging in arrhythmic risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy-associated desmosomal mutation carriers.

OBJECTIVES: The aim of this study was to identify the incremental value and optimal role of cardiac magnetic resonance (CMR) imaging in arrhythmic risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)-associated desmosomal mutation carriers without histories of sustained ventricular arrhythmia. BACKGROUND: Risk stratification of ARVD/C mutation carriers is challenging. METHODS: Sixty-nine patients (mean age 27.0 ± 15.3 years, 42% men) harboring ARVD/C-associated pathogenic mutations (83% plakophilin 2) without prior sustained ventricular arrhythmias were included. Electrocardiographic and 24-h Holter monitoring findings closest to presentation were analyzed for electrical abnormalities per revised task force criteria. CMR studies were done to identify abnormal cardiac structure and function according to the revised task force criteria. RESULTS: Overall, 42 patients (61%) presented with electrical abnormalities on the basis of electrocardiography and Holter monitoring, of whom 20 (48%) had abnormal results on CMR. Only 1 of 27 patients (4%) without electrical abnormalities at initial evaluation had abnormal CMR results. Over a mean follow-up period of 5.8 ± 4.4 years, 11 patients (16%) experienced sustained ventricular arrhythmias, exclusively in patients with both electrical abnormalities (electrocardiography and/or Holter monitoring) and abnormal CMR results. CONCLUSIONS: These results suggest that electrical abnormalities on electrocardiography and Holter monitoring precede detectable structural abnormalities in ARVD/C mutation carriers. Therefore, evaluation of cardiac structure and function using CMR is probably not necessary in the absence of baseline electrical abnormalities. Among ARVD/C mutation carriers, the presence of both electrical and CMR abnormalities identifies patients at high risk for events and thus patients who might benefit from prophylactic implantable cardioverter-defibrillator placement.

Seasonal variation in the frequency of sudden cardiac death and ventricular tachyarrhythmia in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy: the effect of meteorological factors.

BACKGROUND: Sudden cardiac death (SCD) is the most catastrophic presentation in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). OBJECTIVES: To investigate the seasonal variations in the frequency of SCD and ventricular tachyarrhythmia in patients with AVRD/C and to elucidate the meteorological factors that trigger these events. METHODS: From 1998 to 2012, we enrolled 88 consecutive patients with ARVD/C from Taipei City. The cohort included 20 living patients who received implantable cardioverter-defibrillator (ICD) and 68 autopsied patients with SCD from the Taiwan National Forensic Institute registry. The baseline clinical characteristics, seasonal distribution, and associated meteorological factors were explored to predict the occurrences of events, which include appropriate ICD interventions and SCD. RESULTS: There were 106 events, including 38 (35.8%, 1.9 episodes per patient) appropriate ICD interventions in living patients with ARVD/C and 68 (64.2%) SCD events. The seasonal peak occurred predominantly in summer (P < .05) in both groups. For meteorological factors, the onset of event was associated with higher average daily temperature and longer sunshine duration. The variation in humidity within 3 days of events was significantly increased. After multivariate logistic regression analysis, higher average daily temperature and larger variation in humidity were associated with increase in events (odds ratio 1.23, 95% confidence interval 1.16-1.31, P < .001, and odds ratio 1.19, 95% confidence interval 1.15-1.23, P < .001, respectively). CONCLUSIONS: There was seasonal variation with a summer peak in the occurrence of ventricular arrhythmias and SCD in patients with ARVD/C. Meteorological factors including higher temperature and larger variation in humidity within 3 days of events were independently associated with the development of events.

Prevalence of atrial arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy.

BACKGROUND: Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited cardiomyopathy, characterized by right ventricular dysfunction and ventricular arrhythmias. Limited information is available concerning atrial arrhythmias in ARVD/C. OBJECTIVE: The purpose of this study was to characterize spontaneous atrial arrhythmias in a large registry population of ARVD/C patients. METHODS: Patients (n = 248) from the Johns Hopkins ARVD/C registry who met the diagnostic criteria and had undertaken genotype analysis were included. Medical records of each were reviewed to ascertain incidence and characteristics of atrial arrhythmia episodes. Detailed demographic, phenotypic, and structural information was obtained from registry data. RESULTS: Thirty-five patients with ARVD/C (14%) experienced one or more types of atrial arrhythmia during median follow-up of 5.78 (interquartile range 8.52) years. Atrial fibrillation was the most common atrial arrhythmia, occurring in 80% of ARVD/C patients with atrial arrhythmias. Patients developed atrial arrhythmias at a mean age of 43.0 ± 14.0 years. Atrial arrhythmia patients obtained a total of 22 inappropriate implantable cardioverter-defibrillator shocks during follow-up. Older age at last follow-up (P <.001) and male gender (P = .044) were associated with atrial arrhythmia development. Patients with atrial arrhythmias had a higher occurrence of death (P = .028), heart failure (P <.001), and left atrial enlargement on echocardiography (P = .004). CONCLUSION: Atrial arrhythmias are common in ARVD/C and present at a younger age than in the general population. They are associated with male gender, increasing age, and left atrial enlargement. Atrial arrhythmias are clinically important as they are associated with inappropriate implantable cardioverter-defibrillator shocks and increased risk of both death and heart failure.

Exercise increases age-related penetrance and arrhythmic risk in arrhythmogenic right ventricular dysplasia/cardiomyopathy-associated desmosomal mutation carriers.

OBJECTIVES: This study sought to determine how exercise influences penetrance of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) among patients with desmosomal mutations. BACKGROUND: Although animal models and anecdotal evidence suggest that exercise is a risk factor for ARVD/C, there have been no systematic human studies. METHODS: Eighty-seven carriers (46 male; mean age, 44 ± 18 years) were interviewed about regular physical activity from 10 years of age. The relationship of exercise with sustained ventricular arrhythmia (ventricular tachycardia/ventricular fibrillation [VT/VF]), stage C heart failure (HF), and meeting diagnostic criteria for ARVD/C (2010 Revised Task Force Criteria [TFC]) was studied. RESULTS: Symptoms developed in endurance athletes (N = 56) at a younger age (30.1 ± 13.0 years vs. 40.6 ± 21.1 years, p = 0.05); they were more likely to meet TFC at last follow-up (82% vs. 35%, p < 0.001) and have a lower lifetime survival free of VT/VF (p = 0.013) and HF (p = 0.004). Compared with those who did the least exercise per year (lowest quartile) before presentation, those in the second (odds ratio [OR]: 6.64, p = 0.013), third (OR: 16.7, p = 0.001), and top (OR: 25.3, p < 0.0001) quartiles were increasingly likely to meet TFC. Among 61 individuals who did not present with VT/VF, the 13 subjects experiencing a first VT/VF event over a mean follow-up of 8.4 ± 6.7 years were all endurance athletes (p = 0.002). Survival from a first VT/VF event was lowest among those who exercised most (top quartile) both before (p = 0.036) and after (p = 0.005) clinical presentation. Among individuals in the top quartile, a reduction in exercise decreased VT/VF risk (p = 0.04). CONCLUSIONS: Endurance exercise and frequent exercise increase the risk of VT/VF, HF, and ARVD/C in desmosomal mutation carriers. These findings support exercise restriction for these patients.

Malignant arrhythmogenic right ventricular dysplasia/cardiomyopathy with a normal 12-lead electrocardiogram: a rare but underrecognized clinical entity.

BACKGROUND: In Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C), a normal electrocardiogram (ECG) is considered reassuring. However, some patients with ARVD/C experiencing ventricular arrhythmias have a normal ECG. OBJECTIVES: To estimate how often patients with ARVD/C experiencing ventricular arrhythmias have a normal ECG during sinus rhythm, and to provide a clinical profile of these patients. METHODS: We included 145 patients with ARVD/C experiencing a documented sustained ventricular arrhythmia. Conventional 12-lead sinus rhythm ECGs within 6 months of the event were reviewed for diagnostic Task Force Criteria (TFC). ECGs were classified as abnormal (≥1 TFC), nonspecific (abnormal, no TFC), or normal. Cardiologic investigations within 6 months of the event were evaluated as per TFC in those with a nonspecific or normal ECG. RESULTS: The ECG was nonspecific or normal in 17 of 145 (12%) subjects. Mean age of these patients was 41.3 ± 12.4 years and 14 (82%) were men, comparable to those with an abnormal ECG. Most patients with a nonspecific or normal ECG showed ≥1 TFC on Holter monitoring (n = 9 of 10) and signal-averaged ECG (n = 4 of 5), and all had nonsustained ventricular tachycardia recorded. Among 15 patients who underwent structural evaluation, 11 (73%) showed structural TFC (9 major and 2 minor). CONCLUSIONS: Although most patients with ARVD/C experiencing arrhythmias have an abnormal ECG, a nonspecific or normal ECG does not preclude ARVD/C diagnosis. All patients with a nonspecific or normal ECG had alternative evidence of disease expression. These results alert the physician not to rely exclusively on ECG in ARVD/C, but to assess arrhythmic risk by comprehensive clinical evaluation.