Arrhythmogenic right ventricular cardiomyopathy/dysplasia: risk stratification and therapy

Antiarrhythmic Drug Therapy in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable progressive myocardial disorder that predisposes patients to ventricular arrhythmias and sudden cardiac death. Antiarrhythmic medications have an important role in reducing the frequency of ventricular arrhythmias and the morbidity associated with recurrent implantable cardioverter-defibrillator (ICD) shocks. Although several studies have examined the use of antiarrhythmic drugs in ARVC, these have been mostly retrospective in nature and inconsistent in their methodology, patient population and endpoints. Thus, current prescribing practices are largely based on expert opinion and extrapolation from other diseases. Herein, we discuss the major studies of the use of antiarrhythmics in ARVC, present the current approach employed at the Johns Hopkins Hospital and identify areas where further research is needed. Most notably, there is a great need for high-quality studies with consistent methodology and randomized controlled trial data into the use of antiarrhythmic drugs in ARVC. This would improve management of the condition and ensure antiarrhythmic prescribing is based on robust evidence.

Galectin-3 correlates with arrhythmogenic right ventricular cardiomyopathy and predicts the risk of ventricular -arrhythmias in patients with implantable defibrillators

Background Arrhythmogenic right ventricular dysplasia (ARVD) is a heritable disorder characterized by fibro-fatty replacement of right ventricular myocytes, increased risk of ventricular arrhythmias, and sudden cardiac death. Galectin-3 (GAL3) is known to play an important role in a number of fibrotic conditions, including cardiac fibrosis. Many studies have focused on the association between GAL3 levels and cardiac fibrosis in heart failure. However, the role of GAL3 in the pathogenesis of ARVD and ventricular arrhythmias has not yet been evaluated thoroughly. The aim of this study was to explore GAL3 levels in patients with ARVD and its association with ventricular arrhythmias. Methods Twenty-nine patients with ARVD and 24 controls were included. All patients with ARVD had an implantable cardiac defibrillator (ICD) for primary or secondary prevention. Ventricular arrhythmia history was obtained from a chart review and ICD data interrogation. Galectin-3 levels were measured using an enzyme-linked immunosorbent assay. Results Patients with ARVD had higher plasma GAL3 levels (16.9 ± 2.6 ng/mL vs 11.3 ± 1.8 ng/mL, P < 0.001) than the control group. Ten patients had sustained or non-sustained ventricular arrhythmias during follow-up. In the multivariable analysis, left ventricular disease involvement (HR: 1.05; 95% CI: [1.01-1.12]; P = 0.03); functional capacity >2 (HR: 1.21; 95% CI: [1.13-1.31]; P < 0.005); and GAL3 levels (HR: 1.05; 95% CI: [1.00-1.11]; P = 0.01) independently predicted VT/VF. Conclusion We demonstrated that serum GAL3 was significantly elevated in patients with ARVD. Also, serum GAL 3 levels could be regarded as a candidate biomarker in the diagnosis of ARVD which needs to be tested in larger prospective studies. In addition, GAL3 levels were higher in patients with VT/VF as compared with those without VT/VF.

Risk Stratification in Arrhythmic Right Ventricular Cardiomyopathy Without Implantable Cardioverter-Defibrillators

OBJECTIVES

The primary objective of this study is risk stratification of patients with arrhythmic right ventricular cardiomyopathy (ARVC).

BACKGROUND

There is a need to identify those who need an automatic implantable defibrillator (ICD) to prevent sudden death.

METHODS

This is an analysis of 88 patients with ARVC from three centers who were not treated with an ICD.

RESULTS

Risk factors for subsequent arrhythmic deaths were pre-enrollment sustained or nonsustained ventricular tachycardia (VT) and decreased left ventricular function.

CONCLUSION

These factors serve as proposed guidelines for implantation of an ICD in patients with ARVC to prevent sudden death.

12-Lead electrocardiogram as a predictor of sudden cardiac death: from epidemiology to clinical practice

Sudden cardiac death (SCD) causes a high burden of premature deaths in the population affecting subjects of all ages. The identification of subjects at high risk for SCD is of great importance as the prevention of many of these events would be possible with the treatment of underlying cardiac diseases and the use of implantable cardioverter-defibrillators (ICD). However, the current selection of patients for ICD therapy is based solely on left ventricular ejection fraction, and thus a substantial portion of patients at high risk does not qualify for the therapy. Role of the standard electrocardiogram (ECG) in SCD risk stratification has been under active research during the last decade and multiple abnormalities of depolarization and repolarization on the ECG associated with an increased risk of SCD have been identified. In this review, we describe the basic pathophysiological principles behind these changes. We also review the current knowledge of the prognostic significance of ECG predictors of SCD in the general population, and in patients with coronary heart disease (CHD), heart failure, cardiomyopathies, and in inheritable arrhythmia syndromes. Also, insights into the novel digital ECG signal processing techniques are provided.

Arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (AC) is a heart muscle disease clinically characterized by life-threatening ventricular arrhythmias and pathologically by an acquired and progressive dystrophy of the ventricular myocardium with fibro-fatty replacement. Due to an estimated prevalence of 1:2000-1:5000, AC is listed among rare diseases. A familial background consistent with an autosomal-dominant trait of inheritance is present in most of AC patients; recessive variants have also been reported, either or not associated with palmoplantar keratoderma and woolly hair. AC-causing genes mostly encode major components of the cardiac desmosome and up to 50 % of AC probands harbor mutations in one of them. Mutations in non-desmosomal genes have been also described in a minority of AC patients, predisposing to the same or an overlapping disease phenotype. Compound/digenic heterozygosity was identified in up to 25 % of AC-causing desmosomal gene mutation carriers, in part explaining the phenotypic variability. Abnormal trafficking of intercellular proteins to the intercalated discs of cardiomyocytes and Wnt/beta catenin and Hippo signaling pathways have been implicated in disease pathogenesis.

AC is a major cause of sudden death in the young and in athletes. The clinical picture may include a sub-clinical phase; an overt electrical disorder; and right ventricular or biventricular pump failure. Ventricular fibrillation can occur at any stage. Genotype-phenotype correlation studies led to identify biventricular and dominant left ventricular variants, thus supporting the use of the broader term AC.

Since there is no “gold standard” to reach the diagnosis of AC, multiple categories of diagnostic information have been combined and the criteria recently updated, to improve diagnostic sensitivity while maintaining specificity. Among diagnostic tools, contrast enhanced cardiac magnetic resonance is playing a major role in detecting left dominant forms of AC, even preceding morpho-functional abnormalities. The main differential diagnoses are idiopathic right ventricular outflow tract tachycardia, myocarditis, sarcoidosis, dilated cardiomyopathy, right ventricular infarction, congenital heart diseases with right ventricular overload and athlete heart. A positive genetic test in the affected AC proband allows early identification of asymptomatic carriers by cascade genetic screening of family members. Risk stratification remains a major clinical challenge and antiarrhythmic drugs, catheter ablation and implantable cardioverter defibrillator are the currently available therapeutic tools. Sport disqualification is life-saving, since effort is a major trigger not only of electrical instability but also of disease onset and progression. We review the current knowledge of this rare cardiomyopathy, suggesting a flowchart for primary care clinicians and geneticists.

Pharmacotherapy and other therapeutic modalities for managing Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is a genetically determined rare cardiomyopathy (1 in 5000 to 1 in 2000 in the general population), which can lead to ventricular arrhythmias and sudden death (SD). The classic form of the disease has a predilection for the right ventricle (RV), but recognition of left-dominant and biventricular variants led to the broader term "Arrhythmogenic Cardiomyopathy". The disease affects men more frequently than women and becomes clinically overt usually from the second to the fourth decade of life. Treatment consists of restriction of physical exercise, antiarrhythmic drugs, catheter ablation and ICD implantation. These treatments have the potential to change the natural history of the disease by protecting against SD and offering a good-quality and nearly normal life-expectancy. Antiarrhythmic drugs play an important role in terms of reduction of both the number and the complexity of arrhythmias, but they do not reduce the risk of SD. The results of catheter ablation are poor because of the high rate of VT recurrence. ICD should be reserved to selected patients after an accurate risk stratification. The clinical challenge is to improve risk stratification for better identification of those patients who most benefit from the above therapies. Unfortunately, a curative therapy is not yet available.

Prognostic value of endocardial voltage mapping in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Endocardial voltage mapping (EVM) identifies low-voltage right ventricular (RV) areas, which may represent the electroanatomic scar substrate of life-threatening tachyarrhythmias. We prospectively assessed the prognostic value of EVM in a consecutive series of patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D).

METHODS AND RESULTS

We studied 69 consecutive ARVC/D patients (47 males; median age 35 years [28-45]) who underwent electrophysiological study and both bipolar and unipolar EVM. The extent of confluent bipolar (<1.5 mV) and unipolar (<6.0 mV) low-voltage electrograms was estimated using the CARTO-incorporated area calculation software. Fifty-three patients (77%) showed ≥1 RV electroanatomic scars with an estimated burden of bipolar versus unipolar low-voltage areas of 24.8% (7.2-31.5) and 64.8% (39.8-95.3), respectively (P=0.009). In the remaining patients with normal bipolar EVM (n=16; 23%), the use of unipolar EVM unmasked ≥1 region of low-voltage electrogram affecting 26.2% (11.6-38.2) of RV wall. During a median follow-up of 41 (28-56) months, 19 (27.5%) patients experienced arrhythmic events, such as sudden death (n=1), appropriate implantable cardioverter defibrillator interventions (n=7), or sustained ventricular tachycardia (n=11). Univariate predictors of arrhythmic outcome included previous cardiac arrest or syncope (hazard ratio=3.4; 95% confidence interval, 1.4-8.8; P=0.03) and extent of bipolar low-voltage areas (hazard ratio=1.7 per 5%; 95% confidence interval, 1.5-2; P<0.001), whereas the only independent predictor was the bipolar low-voltage electrogram burden (hazard ratio=1.6 per 5%; 95% confidence interval, 1.2-1.9; P<0.001). Patients with normal bipolar EVM had an uneventful clinical course.

CONCLUSIONS

The extent of bipolar RV endocardial low-voltage area was a powerful predictor of arrhythmic outcome in ARVC/D, independently of history and RV dilatation/dysfunction. A normal bipolar EVM characterized a low-risk subgroup of ARVC/D patients.

Association of heart rate variability with arrhythmic events in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is associated with an increased risk of sudden cardiac death (SCD). Risk stratification of ARVC/D patients, however, remains an unresolved issue. In this study we investigated whether heart rate variability (HRV) can be helpful in identifying ARVC/D patients with increased risk of arrhythmic events.

METHODS AND RESULTS

We studied 30 consecutive patients (17 males; 45.4 ± 18 years) with ARVC/D, diagnosed according to guideline criteria; 15 patients (50%) had received an implantable cardioverter defibrillator (ICD) for primary SCD prevention. HRV was assessed on 24-h ECG Holter monitoring. The primary endpoint was the occurrence of major arrhythmic events (SCD, sustained ventricular tachycardia (VT), ICD therapy for sustained VT or ventricular fibrillation (VF)). During the follow-up period (19 ± 7 months), no deaths occurred, but 5 patients (17%) experienced arrhythmic events (4 VTs and 1 VF, all in the ICD group). All HRV parameters were significantly lower in patients with, compared with those without, arrhythmic events. Low-frequency amplitude was the most significant HRV variable associated with arrhythmic events in univariate Cox regression analysis (P=0.017), and was the only significant predictor of arrhythmic events in multivariable regression analysis (hazard ratio 0.88, P=0.047), together with unexplained syncope (hazard ratio 16.1, P=0.039).

CONCLUSIONS

Our data show that among ARVC/D patients HRV analysis might be helpful in identifying those with increased risk of major arrhythmic events.

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.

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.

Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inheritable heart muscle disease characterized by fibrofatty replacement of the right ventricle (RV) and by ventricular arrhythmias potentially leading to sudden cardiac death, mostly in young people and athletes. Later in the disease history, the RV becomes more diffusely involved and left ventricular involvement may result in biventricular heart failure. However, clinical diagnosis of ARVC is often difficult to make in the early stage of the disease because of the broad spectrum of phenotypic manifestations and the nonspecific nature of the disease features. In 1994, an international task force proposed criteria for the clinical diagnosis of ARVC, which have been recently revised to improve their sensitivity. Causative mutations have been identified in approximately half of patients with ARVC. Advances in molecular genetics of ARVC have provided important insight into our understanding of the pathogenesis and pathophysiology of ARVC, which has contributed to the improvement of clinical management. Therapeutic strategies for the prevention of sudden death and disease progression include antiarrhythmic drugs, catheter ablation, and use of an implantable cardioverter defibrillator (ICD). ICD is the most effective tool against arrhythmic sudden death. The implantation of an ICD should be carefully evaluated because of the possibility of device/lead-related complications and inappropriate interventions. This review article focuses on the most current knowledge regarding clinical presentation, diagnosis, molecular genetics, and management strategies of ARVC.

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.

[The ICD as primary prevention. Rare indications]

The most frequent cause of sudden cardiac death (SCD) is underlying coronary artery disease. Healthy appearing young individuals are affected in a minority of cases. These individuals are usually diagnosed with electrical or genetically determined structural heart disease. Arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, long and short QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, and early repolarization syndrome are generally considered rare underlying causes of SCD in these young patients. Affected patients typically present with syncope or cardiac arrest. Occasionally, disease is diagnosed during family screening. Risk stratification is difficult in this patient population. Risk of sudden death has to be weighed individually against risks associated with an implantable cardioverter defibrillator (ICD) in these young patients.

Late presentation of arrhythmogenic right ventricular cardiomyopathy: a case report

Introduction

Arrhythmogenic right ventricular cardiomyopathy is an inherited myocardial disease affecting predominantly young people and manifests as sustained ventricular tachycardia with left bundle branch block morphology, sudden death or isolated right or biventricular heart failure. However, its first manifestation as sustained ventricular tachycardia in older patients without preceding symptoms of heart failure is infrequent. To our knowledge, our patient is among the oldest reported in the literature presenting with ventricular tachycardia because of arrhythmogenic right ventricular cardiomyopathy without preceding symptoms of heart failure.

Case presentation

We present an unusual case of a very late presentation of a right ventricular cardiomyopathy in a 72-year-old white Caucasian man. The patient was admitted with symptoms of weakness, dizziness and chest discomfort for several hours. His electrocardiogram showed a wide-complex tachycardia with left bundle branch block morphology and left axis deviation. Because of continuing hemodynamic instability, the patient was cardioverted to sinus rhythm with a single 300 J shock. His post-cardioversion electrocardiogram, cardiac echocardiogram, coronary angiogram, magnetic resonance imaging and electrophysiological study confirmed the diagnosis of arrhythmogenic right ventricular cardiomyopathy. The patient was treated with an implantable cardioverter defibrillator and discharged on sotalol.

Conclusion

This case report demonstrates that arrhythmogenic right ventricular cardiomyopathy may have a very late presentation and this diagnosis should be considered as a potential cause of sustained ventricular tachycardia of right ventricular origin among the elderly and should be treated accordingly.

Cardiovascular translational medicine (IV): The genetic basis of malignant arrhythmias and cardiomyopathies

The remarkable advances that have taken place in biomedicine over the past 50 years have resulted in dramatic improvements in the prevention, diagnosis and treatment of many diseases. Although cardiology has adopted these advances at a relatively slow pace, today it is fully immersed in this revolution and has become one of the most innovative medical specialties. Research is continuing to give rise to new developments in genetics and molecular biology that lead, almost daily, to innovative ways of preventing, diagnosing and treating the most severe forms of heart disease. Consequently, it is essential that clinical cardiologists have some basic knowledge of genetics and molecular biology as these disciplines are having an increasing influence on clinical practice.

Cardiomyopathy: an overview

Cardiomyopathy is an anatomic and pathologic diagnosis associated with muscle or electrical dysfunction of the heart. Cardiomyopathies represent a heterogeneous group of diseases that often lead to progressive heart failure with significant morbidity and mortality. Cardiomyopathies may be primary (i.e., genetic, mixed, or acquired) or secondary (e.g., infiltrative, toxic, inflammatory). Major types include dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. Although cardiomyopathy is asymptomatic in the early stages, symptoms are the same as those characteristically seen in any type of heart failure and may include shortness of breath, fatigue, cough, orthopnea, paroxysmal nocturnal dyspnea, and edema. Diagnostic studies include B-type natriuretic peptide levels, baseline serum chemistries, electrocardiography, and echocardiography. Treatment is targeted at relieving the symptoms of heart failure and reducing rates of heart failure-related hospitalization and mortality. Treatment options include pharmacotherapy, implantable cardioverter-defibrillators, cardiac resynchronization therapy, and heart transplantation. Recommended lifestyle changes include restricting alcohol consumption, losing weight, exercising, quitting smoking, and eating a low-sodium diet.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: an update

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

Long-range silencing and position effects at telomeres and centromeres: parallels and differences

Most of the human genome is compacted into heterochromatin, a form that encompasses multiple forms of inactive chromatin structure. Transcriptional silencing mechanisms in budding and fission yeasts have provided genetically tractable models for understanding heritably repressed chromatin. These silent domains are typically found in regions of repetitive DNA, that is, either adjacent to centromeres or telomeres or within the tandemly repeated ribosomal DNA array. Here we address the mechanisms of centromeric, telomeric and locus-specific gene silencing, comparing simple and complex animals with yeast. Some aspects are universally shared, such as histone-tail modifications, while others are unique to either centromeres or telomeres. These may reflect roles for heterochromatin in other chromosomal functions, like kinetochore attachment and DNA ends protection.