Natural history and risk stratification of arrhythmogenic right ventricular dysplasia/cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy: an update on pathophysiology, genetics, diagnosis, and risk stratification

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy accounting for life-threatening ventricular tachyarrhythmias and sudden death in young individuals and athletes. Over the past years, mutations in desmosomal genes have been identified as disease-causative. However, genetic heterogeneity and variable phenotypic expression alongside with diverse disease progression still render the evaluation of its prognostic implication difficult. ARVC was initially entered into the canon of cardiomyopathies of the World Health Organization in 1995, and international efforts have resulted in the 2010 modified diagnostic criteria for ARVC. Despite all additional insights into pathophysiology, clinical management, and modern risk stratification, under-/misdiagnosing of ARVC remains a problem and hampers reliable statements on the incidence, prevalence, and natural course of the disease.This review provides a comprehensive overview of the current literature on the pathogenesis, diagnosis, treatment, and prognosis of ARVC and sheds some light on potential new developments in these areas.

Impact of new electrocardiographic criteria in arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (AC) has originally been described as a disorder characterized by fibrofatty replacement of the myocardium, primarily of the right ventricle (RV), and ventricular tachyarrhythmias, sudden death, and at a late stage progressive heart failure. Arrhythmogenic right ventricular dysplasia or cardiomyopathy (ARVD/C) was the previous name of the disease. However, similar histopathologic changes are also found in the left ventricle (LV). AC is also considered a hereditary disease. Recent molecular genetic studies provide accumulating evidence that fibrofatty replacement is preceded by mutation-related desmosomal changes. Desmosomal dysfunction may lead to mechanical and thereafter electrical uncoupling, ultimately resulting in conduction delay. This activation delay and conduction block, provide a substrate for re-entrant mechanisms and thereby ventricular tachycardia (VT). The gold standard for AC diagnosis is demonstration of transmural fibrofatty replacement in cardiac tissue obtained by autopsy or surgery. To facilitate diagnosis in clinical practice, an international Task Force defined in 1994 a set of criteria (TFC) based on electrocardiographic, functional and morphologic features, and family history. These criteria have recently been revised. Routine 12-lead electrocardiography is one of the most important tools for AC diagnosis in all stages of the disease. Even in the absence of other markers in the early concealed stage of the disease, in line with early slow conduction and electrical uncoupling ECG analysis may contribute to early diagnosis. Activation delay and site of origin of VT are reflected in various characteristics of the surface 12-lead electrocardiogram. Since the ECG is easy to obtain, this technique is particularly useful, for both diagnosis and follow up of disease progression.

Prognostic value of QRS fragmentation in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

CONTEXT

QRS fragmentation, including epsilon potentials, terminal activation delay and prolonged S wave upstroke, has been recently described as a diagnostic criterion of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). Whether QRS fragmentation is a marker of recurrent ventricular tachycardia, primary ventricular fibrillation, implantable cardioverter defibrillator (ICD) discharge and sudden cardiac death in these patients is unknown.

RESULTS

Three hundred and thirty-five patients (167 men, mean age 46.3 ± 14.6 years) with ARVC/D according to International Society and Federation of Cardiology/European Society of Cardiology (ISFC/ESC) criteria were analyzed retrospectively. Patients with complete and incomplete right bundle branch block were excluded from the analysis. At 6.3 ± 3.1 years mean follow-up, seven patients (0.02%) had died suddenly, 39 patients (0.13%) experienced recurrent ventricular tachycardia, 32 patients (0.1%) presented with primary ventricular fibrillation and 30 patients (0.1%) had recurrent ICD discharges. QRS fragmentation was significantly associated with arrhythmic events (P < 0.0000001 for the endpoint of sudden cardiac death, P < 0.01 for recurrent ventricular tachycardia, P < 0.0001 for primary ventricular fibrillation and P < 0.001 for recurrent ICD discharges, respectively).

CONCLUSION

QRS fragmentation predicts arrhythmic events in patients with ARVC/D. Further, properly designed prospective studies are warranted to confirm these findings.

Early detection of regional functional abnormalities in asymptomatic ARVD/C gene carriers

BACKGROUND

The overt stage of arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) is preceded by a concealed stage with minor or no signs of disease. However, sudden death may occur in this early phase. Deformation imaging may contribute to early diagnosis. The aims of this study were to compare the diagnostic accuracy of the conventional (1994) versus the recently published (2010) new echocardiographic criteria for ARVD/C and to evaluate the additional value of echocardiographic tissue deformation imaging to detect subclinical RV functional abnormalities in asymptomatic carriers of pathogenic ARVD/C mutations.

METHODS

Fourteen asymptomatic first-degree relatives of ARVD/C probands (the ARVD/C-r group; mean age, 38.0 ± 13.2 years) with a pathogenic plakophilin-2 mutation and a group of age-matched controls (n = 56; mean age, 38.2 ± 12.7 years) were included at a 1:4 ratio. A complete echocardiographic evaluation (dimensions, global systolic parameters, and visual assessment and deformation imaging of the RV free wall including Doppler tissue imaging and two-dimensional strain echocardiography) was obtained. Peak systolic strain less negative than -18% and/or postsystolic shortening (postsystolic index > 15%) in any RV segment was considered abnormal.

RESULTS

RV dimensions in the ARVD/C-r group were similar to those in controls (RV outflow tract, 15.4 ± 2.9 vs 14.4 ± 1.9 mm/m(2), P = NS; RV inflow tract, 18.6 ± 2.6 vs 19.1 ± 2.6 mm/m(2), P = NS), and global systolic parameters were moderately reduced (tricuspid annular plane systolic excursion, 20.0 ± 3.2 vs 23.9 ± 2.8 mm, P = .001; RV fractional area change, 40.3 ± 8.4 vs 40.6 ± 7.1, P = NS). According to task force criteria, 57% of the ARVD/C-r group and 29% of controls were classified as abnormal when applying the 1994 criteria and 29% and 4% when applying the 2010 criteria, respectively. Doppler tissue imaging and two-dimensional strain deformation (and strain rate) values were reduced in the ARVD/C-r group in the basal and mid RV segments compared with controls (P < .001). In the ARVD/C-r group, peak systolic strain less negative than -18% was seen in six patients (43%), postsystolic strain in nine (64%), and either abnormality in 10 (71%), almost exclusively in the basal segment; these findings were observed in none of the controls.

CONCLUSIONS

The 2010 criteria for ARVD/C improve specificity, whereas sensitivity is significantly reduced in this asymptomatic population. In contrast, echocardiographic deformation imaging detects functional abnormalities in the subtricuspid region in 71% of asymptomatic carriers of a pathogenic plakophilin-2 mutation, while regional deformation was normal in all control subjects, indicating superiority of both sensitivity and specificity with these new modalities.

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.

Restricting sports for athletes with heart disease: are we saving lives, avoiding lawsuits, or just promoting obesity and sedentary living?

Sudden cardiac death in young competitive athletes is tragic and usually due to unsuspected cardiovascular disease. Screening programs for athletes remain debatable, and restriction of athletes from sports can have physical, emotional, and legal ramifications. In this article, we review the epidemiology of the more common inherited arrhythmias and congenital heart diseases that are of concern in a newly diagnosed athlete. A comparison of the current American Heart Association/American College of Cardiology and European Society guidelines, which are primarily based on expert opinion due to lack of randomized studies, is then undertaken. Furthermore, certain legal repercussions associated with both qualifying and restricting athletes from competitive sports are discussed. Lastly, we urge physicians to keep in mind that disqualifying an athlete from competitive sports does not mean restriction of all activities, and even patients with inherited arrhythmias and congenital heart disease can participate in low to moderate activity complementary with a healthy lifestyle.

Long-term follow-up in patients with arrhythmogenic right ventricular cardiomyopathy

INTRODUCTION

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of sudden cardiac death due to tachyarrhythmias. The purpose of this study was to investigate the long-term prognosis in patients with ARVC and the incidence of rapid ventricular arrhythmias during follow-up.

METHODS

Thirty ARVC patients (19 male, 63.3%, mean age 48 ± 15 years) fulfilling modified Task Force criteria 2010 were included. Of them, 13 patients (43.3%) received implantable cardioverter-defibrillator (ICD) implantation. Rapid ventricular arrhythmia was defined as electrical storm or the occurrence of ventricular tachycardia (VT) or ventricular fibrillation (VF) with a cycle length of 240 ms or less that necessitate shock delivery to 2 or more times within a 24-hour period.

RESULTS

With a mean follow-up of 68 ± 10 months, 6 patients (20%) with ICD implantation had recurrent rapid VT/VF. One (3.3%) of them died of multiple shocks and SCD, and 5 (16.7%) had multiple ICD therapies due to VT/VF and electrical storm. The interval between the diagnosis of ARVC and occurrence of rapid VT/VF was 13.4 ± 4.9 months. Most (5/6, 83.3%) events of recurrent rapid VT/VF occurred within 2 years. Ablated patients who did not receive an ICD implant were totally free of rapid VT/VF.

CONCLUSIONS

For patients with ARVC, long-term prognosis is favorable. During a long-term follow-up, patients meeting the criteria for ICD implantation have a higher rate of rapid and potentially life-threatening arrhythmias. However, early and clustered recurrence of rapid VT/VF in patients with an ICD is common, whereas late occurrence of rapid VT/VF is very rare.

Plasma BIN1 correlates with heart failure and predicts arrhythmia in patients with arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disorder involving diseased cardiac muscle. Bridging integrator 1 (BIN1) is a membrane-associated protein important to cardiomyocyte homeostasis and is downregulated in cardiomyopathy. We hypothesized that BIN1 could be released into the circulation and that blood-available BIN1 can provide useful data on the cardiac status of patients whose hearts are failing secondary to ARVC.

OBJECTIVE

To determine whether plasma BIN1 levels can be used to measure disease severity in patients with ARVC.

METHODS

We performed a retrospective cohort study of 24 patients with ARVC. Plasma BIN1 levels were assessed for their ability to correlate with cardiac functional status and predict ventricular arrhythmias.

RESULTS

Mean plasma BIN1 levels were decreased in patients with ARVC with heart failure (15 ± 7 vs 60 ± 17 in patients without heart failure, P <.05; the plasma BIN1 level was 60 ± 10 in non-ARVC normal controls). BIN1 levels correlated inversely with number of previous ventricular arrhythmia (R = -.47; P <.05), and low BIN1 levels correctly classified patients with advanced heart failure or ventricular arrhythmia (receiver operator curve area under the curve of 0.88 ± 0.07). Low BIN1 levels also predicted future ventricular arrhythmias (receiver operator curve area under the curve of 0.89 ± 0.09). In a stratified analysis, BIN1 levels could predict future arrhythmias in patients without severe heart failure (n = 20) with an accuracy of 82%. In the 7 patients with ARVC with serial blood samples, all of whom had evidence of disease progression during follow-up, plasma BIN1 levels decreased significantly (a decrease of 63%; P <.05).

CONCLUSIONS

Plasma BIN1 level seems to correlate with cardiac functional status and the presence or absence of sustained ventricular arrhythmias in a small cohort of patients with ARVC and can predict future ventricular arrhythmias.

[Arrhythmogenic cardiomyopathy. Patterns of ventricular involvement using cardiac magnetic resonance]

INTRODUCTION AND OBJECTIVES

Biventricular arrhythmogenic cardiomyopathy and left dominant arrhythmogenic cardiomyopathy forms had recently been included in the spectrum of arrhythmogenic cardiomyopathy. The aim of the study was to describe, using cardiovascular magnetic resonance, the patterns of ventricular involvement as well as late gadolinium enhancement in these conditions.

METHODS

Medical databases and records from the cardiology units of 3 hospitals were reviewed to obtain data from patients with arrhythmogenic cardiomyopathy.

RESULTS

Twenty-six consecutive patients were included (40 [16] years, 16 males). Right ventricle involvement was present in 19 patients (73%). Among them, 13 patients (50%) had volumes over the upper limit of normality, 11 (42%) patients had late gadolinium enhancement in right ventricle and 6 patients (23%) had just mild involvement with wall motion abnormalities or microaneurysms. Left ventricle involvement was present in 24 patients (92%), all of them with late gadolinium enhancement. In 15 patients (57%) left ventricular systolic dysfunction was observed, and dilatation in 3 patients (11%). Late gadolinium enhancement was more frequent in the inferior, lateral, and inferolateral walls (65%, 57%, and 61% of patients, respectively) while septum was seldom affected (26% of cases). The pattern of late gadolinium enhancement was mainly subepicardial (46% of patients) or transmural (19%), and was intramyocardial in only 12% of the cases.

CONCLUSIONS

In this sample, left ventricle involvement is very common. The most frequent finding was left ventricular late gadolinium enhancement, while the least frequent was dilatation. The pattern of late gadolinium enhancement was more frequently subepicardial and located in the inferior and inferolateral walls.

A case of arrythmogenic right ventricular cardiomyopathy in a middle-aged woman

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a kind of heart muscle disease characterized by the gradual replacement of the right ventricular myocardium with fibrous tissue and fat. It could be the major cause of sudden cardiac death with ventricular tachycardia, and there is a variation in the history of the disease. We reported an unusual case of ARVC in a middle-aged woman with congestive heart failure as her first presentation for a long time.

Diagnostic accuracy and variability of three semi-quantitative methods for assessing right ventricular systolic function from cardiac MRI in patients with acquired heart disease

OBJECTIVES

To evaluate the diagnostic accuracy and variability of 3 semi-quantitative (SQt) methods for assessing right ventricular (RV) systolic function from cardiac MRI in patients with acquired heart disease: tricuspid annular plane systolic excursion (TAPSE), RV fractional-shortening (RVFS) and RV fractional area change (RVFAC).

METHODS

Sixty consecutive patients were enrolled. Reference RV ejection fraction (RVEF) was determined from short axis cine sequences. TAPSE, RVFS and RVFAC were measured on a 4-chamber cine sequence. All SQt analyses were performed twice by 3 observers with various degrees of training in cardiac MRI. Correlation with RVEF, intra- and inter-observer variability, and receiver operating characteristic (ROC) curve analysis were performed for each SQt method.

RESULTS

Correlation between RVFAC and RVEF was good for all observers and did not depend on previous cardiac MRI experience (R range = 0.716-0.741). Conversely, RVFS (R range = 0.534-0.720) and TAPSE (R range = 0.482-0.646) correlated less with RVEF and depended on previous experience. Intra- and inter-observer variability was much lower for RVFAC than for RVFS and TAPSE. ROC analysis demonstrated that RVFAC <41% could predict a RVEF <45% with 90% sensitivity and 94% specificity.

CONCLUSIONS

RVFAC appears to be more accurate and reproducible than RVFS and TAPSE for SQt assessment of RV function by cardiac MRI.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: a review and update

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a predominantly genetically determined and heritable form of cardiomyopathy that is characterized pathologically by the replacement of myocytes by adipose and fibrous tissue and leads to right ventricular failure, arrhythmias, and sudden cardiac death. The estimated prevalence of ARVC/D in the general population ranges from 1 in 2,000 to 1 in 5,000, men are more frequently affected than women, with an approximate ratio of 3:1. ARVC/D can be inherited as an autosomal dominant disease with reduced penetrance and variable expression, autosomal recessive inheritance is also described. There have been 12 genes identified which are linked to ARVC/D, encoding several components of the cardiac desmosome. Dysfunctional desmosomes resulting in defective cell adhesion proteins, such as plakoglobin (JUP), desmoplakin (DSP), plakophilin-2 (PKP-2), and desmoglein-2 (DSG-2) consequently cause loss of electrical coupling between cardiac myocytes, leading to myocyte cell death, fibrofatty replacement and arrhythmias. Diagnosis is based on the finding a combination of characteristic abnormalities in family history, electrocardiography, cardiac imaging as well as endomyocardial biopsy (original task force criteria). Therapeutic options remain limited because of the progressive nature of ARVC/D. Competitive athletics should be avoided. Patients with ARVC/D with a history of having been resuscitated from sudden cardiac death, patients with syncope, very young patients, and those who have marked right ventricular involvement are at the highest risk for arrhythmic death and also, the presence of left ventricular involvement is a risk factor. Several authors concluded that patients who meet the Task Force criteria for ARVC/D are at high risk for sudden cardiac death and should undergo ICD placement for primary and secondary prevention, regardless of electrophysiologic testing results. The role of electrophysiologic study and VT catheter ablation in ARVC/D remains poorly defined, and is frequently used as a palliative measure for patients with refractory VT. The progressive nature of ARVC/D suggests that catheter ablation would not be a long-term curative procedure. Sotalol proved to be highly effective in patients with ARVC/D and inducible as well as non-inducible ventricular tachycardia; if it is ineffective in inducible ventricular tachycardia response to other antiarrhythmic drugs is unlikely and therefore non-pharmacological therapy without further drug testing should be considered. Orthotopic heart transplantation is considered in patients with progressive heart failure and intractable recurrent ventricular arrhythmias.

Prognostic predictors in arrhythmogenic right ventricular cardiomyopathy: results from a 10-year registry

AIMS

We sought to examine the clinical presentation and natural history and to identify long-term prognostic predictors in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) as information concerning the natural history and risk stratification of ARVC is still incomplete.

METHODS AND RESULTS

A cohort of 96 ARVC patients (68% males, 35 ± 15 years) was enrolled and underwent structured diagnostic protocol and follow-up. Primary study endpoints were death and heart transplantation (HTx). Clinical and echo-Doppler data were assessed as prognostic indicators. Sixty-five per cent of patients had right ventricular (RV) systolic dysfunction (RV fractional area change < 33%) and 24% had left ventricular (LV) systolic dysfunction (LV ejection fraction <50%). During a mean follow-up of 128 ± 92 months, 20 patients (21%) experienced cardiac death or underwent HTx. At multivariate analysis (Model 1), RV dysfunction [hazard ratio (HR): 4.12; 95% confidence interval (CI): 1.01-18.0; P = 0.05], significant tricuspid regurgitation (HR: 7.6; 95% CI: 2.6-22.0; P < 0.001), and amiodarone treatment (HR: 3.4; 95% CI: 1.3-8.8; P = 0.01) resulted as predictors of death/HTx. When inserting in the model, the 'ordinal dysfunction' (Model 2), which considers the presence of both RV and LV dysfunctions, this variable emerged as an independent prognostic predictor (HR: 6.3; 95% CI: 2.17-17.45; P < 0.001). At the receiver operating characteristic analysis, Model 2 was significantly more accurate in predicting long-term outcome compared with Model 1 (area under the curve 0.84 vs. 0.78, respectively; P = 0.04).

CONCLUSION

In our tertiary referral centre ARVC population, the presence of LV dysfunction at diagnosis has an incremental power in predicting adverse outcome compared with RV dysfunction alone.

Arrhythmogenic forms of heart failure in children

There are various underlying causes of tachycardia-induced cardiomyopathy (TIC), and it is critical that it be considered in any patient who presents with a newly diagnosed dilated cardiomyopathy. Unlike most other forms of cardiomyopathy, TIC should be considered a treatable form of cardiomyopathy and it is imperative that the diagnosis be fully considered. A 12-lead ECG should be obtained in all patients with a dilated cardiomyopathy. Prompt diagnosis and therapy of this relatively uncommon cause of heart failure is critical and has the potential to completely reverse the ventricular dysfunction that may be present in this abnormality.

Arrhythmia and right heart disease: from genetic basis to clinical practice

Historically, left ventricular cardiomyopathy and coronary heart disease have been regarded as the main causes of ventricular arrhythmia and sudden cardiac death. However, within last two decades, arrhythmias originating from the right ventricle have begun to attract the attention of the scientific world for a number of reasons. Ventricular arrhythmias originating from the right ventricle usually affect younger patients and can lead to sudden cardiac death. The pathophysiologic mechanism of these arrhythmias is not fully understood, which can leave room for a range of different interpretations. Moreover, the intriguing world of genetics is increasingly being drawn into the pathogenesis, diagnosis and prognosis of some of these arrhythmias. This review considers the pathogenesis, diagnosis and treatment of arrhythmogenic right ventricular cardiomyopathy or dysplasia (ARVD), Brugada syndrome, right ventricular outflow tract ventricular tachycardia, and arrhythmias in the right side of the heart due to congenital heart disease. In addition, because ventricular arrhythmias associated with right ventricular heart diseases such as Brugada syndrome and ARVD can explain up to 10-30% of sudden cardiac deaths in young adults in the general population and an even greater percentage in young athletes, this article contains a brief analysis of screening tests used before participation in sports, life-style modification, and treatment options for athletes affected by these conduction disorders.

[Arrhytmogenic right ventricle--prognostic significance of exercise test]

The authors summarize the present knowledge on arrhythmogenic right ventricular cardiomyopathy/dysplasia. Limited data are available about natural history of asymptomatic patients with arrhythmogenic right ventricle cardiomyopathy/dysplasia, who have a ventricular tachycardia during exercise test. A 25-year old female patient was treated with osteosynthesis because of ankle injury. Cardiology consultation was performed because of an abnormal ECG. Physical examination was normal. ECG showed a normal sinus rhythm, left axis deviation, negative T waves in leads II, III, aVF and V2-V6. Chest X-ray and laboratory findings were normal. Echocardiography showed normal left ventricular ejection fraction along with inferior akinesis and dilated right ventricle. Bicycle exercise test revealed a good exercise tolerability (9 MET), and after sporadic ventricular extra systoles ventricular tachycardia developed lasting for 3 minutes, which spontaneously stopped after aborting the test and performed abdominal strain. MRI was performed which has shown normal left ventricular size, wall motion and ejection fraction and depressed right ventricle function (ejection fraction 31.6%) enlarged right ventricular end-systolic and diastolic volumes, hypo-akinetic regions without aneurysm and bulging. No contrast enhancement was seen in the thin right ventricular wall. According to abnormal ECG and MRI findings arrhythmogenic right ventricle cardiomyopathy/dysplasia was diagnosed. No ICD implantation was indicated because the patient was asymptomatic, and no sudden cardiac death occurred in the family. Three month later the patient was found dead. At autopsy the right ventricular chamber was markedly enlarged, with multiple translucent areas of fatty accumulation accompanied with extended myocytes loss. There was a characteristic triangle dysplasia: the inflow, outflow tracts and apical areas. The coronaries were free of atherosclerosis. Mallory's phosphotungstic acid-hematoxilin stain demonstrated the presence of fibrosis within the scattered myocardium.

CONCLUSION

malignant ventricular arrhythmia provoked by exercise test in an asymptomatic arrhythmogenic right ventricle cardiomyopathy/dysplasia patient with negative family history should be an indication for ICD implantation.

Value of the signal-averaged electrocardiogram in arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited disease that causes structural and functional abnormalities of the right ventricle (RV). The presence of late potentials as assessed by the signal-averaged electrocardiogram (SAECG) is a minor task force criterion.

OBJECTIVE

The purpose of this study was to examine the diagnostic and clinical value of the SAECG in a large population of genotyped ARVC/D probands.

METHODS

We compared the SAECGs of 87 ARVC/D probands (age 37 ± 13 years, 47 males) diagnosed as affected or borderline by task force criteria without using the SAECG criterion with 103 control subjects. The association of SAECG abnormalities was also correlated with clinical presentation, surface ECG, ventricular tachycardia (VT) inducibility at electrophysiologic testing, implantable cardioverter-defibrillator therapy for VT, and RV abnormalities as assessed by cardiac magnetic resonance imaging (cMRI).

RESULTS

Compared with controls, all three components of the SAECG were highly associated with the diagnosis of ARVC/D (P <.001). They include the filtered QRS duration (97.8 ± 8.7 ms vs 119.6 ± 23.8 ms), low-amplitude signal (24.4 ± 9.2 ms vs 46.2 ± 23.7 ms), and root mean square amplitude of the last 40 ms of the QRS (50.4 ± 26.9 μV vs 27.9 ± 36.3 μV). The sensitivity of using SAECG for diagnosis of ARVC/D was increased from 47% using the established 2 of 3 criteria (i.e., late potentials) to 69% by using a modified criterion of any 1 of 3 criteria, while maintaining a high specificity of 95%. Abnormal SAECG as defined by this modified criterion was associated with a dilated RV volume and decreased RV ejection fraction detected by cMRI (P <.05). SAECG abnormalities did not vary with clinical presentation or reliably predict spontaneous or inducible VT and had limited correlation with ECG findings.

CONCLUSION

Using 1 of 3 SAECG criteria contributed to increased sensitivity and specificity for the diagnosis of ARVC/D. This finding is incorporated in the recent modification of the task force criteria.

Prophylactic implantable defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation or sustained ventricular tachycardia

BACKGROUND

The role of implantable cardioverter-defibrillator (ICD) in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior ventricular fibrillation (VF) or sustained ventricular tachycardia is an unsolved issue.

METHODS AND RESULTS

We studied 106 consecutive patients (62 men and 44 women; age, 35.6±18 years) with arrhythmogenic right ventricular cardiomyopathy/dysplasia who received an ICD based on 1 or more arrhythmic risk factors such as syncope, nonsustained ventricular tachycardia, familial sudden death, and inducibility at programmed ventricular stimulation. During follow-up of 58±35 months, 25 patients (24%) had appropriate ICD interventions and 17 (16%) had shocks for life-threatening VF or ventricular flutter. At 48 months, the actual survival rate was 100% compared with the VF/ventricular flutter-free survival rate of 77% (log-rank P=0.01). Syncope significantly predicted any appropriate ICD interventions (hazard ratio, 2.94; 95% confidence interval, 1.83 to 4.67; P=0.013) and shocks for VF/ventricular flutter (hazard ratio, 3.16; 95% confidence interval, 1.39 to 5.63; P=0.005). The positive predictive value of programmed ventricular stimulation was 35% for any appropriate ICD intervention and 20% for shocks for VF/ventricular flutter, with a negative predictive value of 70% and 74%. None of the 27 asymptomatic patients with isolated familial sudden death had appropriate ICD therapy. Twenty patients (19%) had inappropriate ICD interventions, and 18 (17%) had device-related complications.

CONCLUSIONS

One fourth of patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia and no prior sustained ventricular tachycardia or VF had appropriate ICD interventions. Syncope was an important predictor of life-saving ICD intervention and is an indication for ICD. Prophylactic ICD may not be indicated in asymptomatic patients because of their low arrhythmic risk regardless of familial sudden death and programmed ventricular stimulation findings. Programmed ventricular stimulation had a low predictive accuracy for ICD therapy.

Magnetic resonance imaging assessment of arrhythmogenic right ventricular cardiomyopathy/dysplasia in children

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a genetically determined disease that progresses continuously from conception and throughout life. ARVC/D manifests predominantly in young adulthood. Early identification of the concealed cases in childhood is of utmost importance for the prevention of sudden cardiac death later in life. Magnetic resonance imaging (MRI) is routinely requested in patients with a confirmed or suspected diagnosis of ARVC/D and in family members of the patients with ARVC/D. Although the utility of MRI in the assessment of ARVC/D is well recognized in adults, MRI is a low-yield test in children as the anatomical, histological, and functional changes are frequently subtle or not present in the early phase of the disease. MRI findings of ARVC/D include morphologic changes such as right ventricular dilatation, wall thinning, and aneurismal outpouchings, as well as abnormal tissue characteristics such as myocardial fibrosis and fatty infiltration, and functional abnormalities such as global ventricular dysfunction and regional wall motion abnormalities. Among these findings, regional wall motion abnormalities are the most reliable MRI findings both in children and adults, while myocardial fibrosis and fat infiltration are rarely seen in children. Therefore, an MRI protocol should be tailored according to the patient's age and compliance, as well as the presence of other findings, instead of using the protocol that is used for adults. We propose that MRI in children with ARVC/D should focus on the detection of regional wall motion abnormalities and global ventricular function by using a cine imaging sequence and that the sequences for myocardial fat and late gadolinium enhancement of the myocardium are reserved for those who show abnormal findings at cine imaging. Importantly, MRI should be performed and interpreted by experienced examiners to reduce the number of false positive and false negative readings.

Arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) originally emerged as a pathologic diagnosis based on distinctive autopsy findings in cases of premature sudden death. Subsequently these characteristic pathologic features were associated with ventricular tachycardia of right ventricular origin and syncope. ARVC is a rare condition and our understanding of the disorder has been confounded by multiple small, highly selected series. Driven by both family studies and improved non-invasive imaging tools the clinical diagnosis of ARVC has broadened, in some instances extending far beyond the original limits of the syndrome. In recent years false-positive diagnoses have increased, thus stimulating investigators to move toward more rigorous clinical criteria. Despite the efforts of a Task Force to establish a baseline for subsequent empiric testing, these criteria have often inadvertently been used as a definitive diagnostic tool in the absence of prospective data. Recent genetic studies have revealed substantial etiologic heterogeneity, and ARVC is emerging as a syndrome consisting of multiple discrete disease entities, in part explaining the tremendous variation in clinical features and natural history seen in prior reports.

Some previously neglected examples of arrhythmogenic right ventricular dysplasia/cardiomyopathy and frequency of its various reported manifestations

Four patients are described with either parchment-like thinning or partial but extensive myocyte depletion with severe fatty or fibrofatty infiltration of the free wall of the right ventricle in its outflow tract, including 2 previously reported patients who also had focal parchment-like thinning of the left ventricular free wall. Three had documented ventricular tachycardia, and the remaining patient had sudden death as his first and only manifestation of heart disease. Three patients had severe heart failure: in 1, it was fatal, and the other 2 underwent cardiac transplantation. Necropsy cases of parchment-heart syndrome before 1980 are reviewed, as well as large series of cases with arrhythmogenic right ventricular dysplasia (ARVD) reported subsequently. It is suggested that ARVD is not an ideal name for this condition, because malignant ventricular arrhythmias are not universal, the left ventricular free wall and/or ventricular septum are sometimes involved, and the name "ARVD" neglects the fact that severe heart failure may be prominent in these patients. The right ventricular wall can be thin or parchment-like, or it may not be thinned but consist mainly of adipose tissue with or without focal fibrous tissue and a few islands of myocytes. Nevertheless, because the name "ARVD" has been commonly used and recognized for >30 years, it is probably best retained for this condition.

Usefulness of precordial T-wave inversion to distinguish arrhythmogenic right ventricular cardiomyopathy from idiopathic ventricular tachycardia arising from the right ventricular outflow tract

The 2 predominant causes of ventricular tachycardia (VT) arising from the right ventricle are arrhythmogenic right ventricular cardiomyopathy (ARVC) and idiopathic VT arising from the right ventricular outflow tract (RVOT). These arrhythmias can be adrenergically mediated and may be difficult to distinguish clinically. A minor criterion for the diagnosis of ARVC is T-wave inversion (TWI) in the right precordial leads during sinus rhythm. However, there have been reports of precordial TWI identified in patients with RVOT tachycardia. The purpose of this study was to determine whether patterns of precordial TWI could differentiate between the 2 groups. A multicenter registry of 229 patients with VT of right ventricular origin was evaluated. After appropriate exclusions (n = 29), 79 patients (58% men, mean age 40 +/- 14 years) had ARVC, and 121 patients (41% men, mean age 48 +/- 14 years) had RVOT tachycardia. During sinus rhythm, 37 patients (47%) with ARVC and 5 patients (4%) with RVOT tachycardia had TWI in leads V(1) to V(3). For the diagnosis of ARVC, TWI in leads V(1) to V(3) had sensitivity of 47% and specificity of 96%. In conclusion, in patients with VT of right ventricular origin, the presence of TWI in electrocardiographic leads V(1) to V(3) supports the diagnosis of ARVC.

Ordered assembly of the adhesive and electrochemical connections within newly formed intercalated disks in primary cultures of adult rat cardiomyocytes

The intercalated disk (ID) is a complex structure that electromechanically couples adjoining cardiac myocytes into a functional syncitium. The integrity of the disk is essential for normal cardiac function, but how the diverse elements are assembled into a fully integrated structure is not well understood. In this study, we examined the assembly of new IDs in primary cultures of adult rat cardiac myocytes. From 2 to 5 days after dissociation, the cells flatten and spread, establishing new cell-cell contacts in a manner that recapitulates the in vivo processes that occur during heart development and myocardial remodeling. As cells make contact with their neighbors, transmembrane adhesion proteins localize along the line of apposition, concentrating at the sites of membrane attachment of the terminal sarcomeres. Cx43 gap junctions and ankyrin-G, an essential cytoskeletal component of voltage gated sodium channel complexes, were secondarily recruited to membrane domains involved in cell-cell contacts. The consistent order of the assembly process suggests that there are specific scaffolding requirements for integration of the mechanical and electrochemical elements of the disk. Defining the relationships that are the foundation of disk assembly has important implications for understanding the mechanical dysfunction and cardiac arrhythmias that accompany alterations of ID architecture.