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

Clinical manifestations of arrhythmogenic right ventricular cardiomyopathy in Korean patients

BACKGROUND

The clinical manifestations of the Korean patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) are not well known.

METHODS

The clinical data of Korean patients who met the Task Force Criteria for ARVC were analyzed.

RESULTS

Thirty-seven patients (41.2+/-14.8 years old, 19 males) were diagnosed with ARVC. The commonest presenting symptoms were palpitations (30%), syncope/presyncope (30%) and no symptoms (30%). Four patients had a family history of premature sudden death or ARVC. Most patients with no symptoms were evaluated due to ECG abnormalities or asymptomatic ventricular arrhythmias. Ventricular tachycardia, ventricular fibrillation and frequent premature ventricular contractions only were observed in 35%, 5% and 24%, respectively. Wall motion abnormalities of the right and left ventricles were detected in 92% and 41%, respectively. Fatty or fibrofatty infiltration was observed in 26 of the 32 (81%) patients who underwent an endomyocardial biopsy. Two patients had signs of heart failure. Two patients with syncope/presyncope were diagnosed with vasovagal syncope and another was due to side effects from a medication. Most of the patients with ventricular arrhythmias were treated with beta-blockers and/or amiodarone. Implantable cardioverter-defibrillators (ICDs) were implanted in 3 patients. During a mean follow-up of 27.4+/-26.5 months no syncope or sudden death developed except for in one patient with an ICD who suffered from recurrent shocks due to ventricular fibrillation.

CONCLUSIONS

ARVC may be an important cause of syncope, ventricular arrhythmias, and ECG and wall motion abnormalities of the ventricles in Koreans. The Korean patients with ARVC exhibited various clinical manifestations.

Treatment of athletes with cardiac disease or arrhythmias

Ventricular arrhythmias and sudden cardiac death in the athlete are uncommon but extremely visible because of the high profile of amateur and professional athletes. In athletes under the age of 30 years, the incidence of sudden death is low and in most cases occurs in individuals with inherited heart disease. In the older athlete, sudden death is more common and is generally due to arrhythmias in the context of coronary artery disease. Many athletes with aborted sudden death, arrhythmia-related syncope, or high-risk genetic disorders benefit from therapy with implantable cardioverter-defibrillators (ICDs). Although ICD therapy can effectively abort sudden death, implantation of an ICD generally prohibits an individual from all competitive athletics except low-intensity sports. Recommendations for participation in competitive athletics generally follow the recently published 36th Bethesda Conference Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities.

Sudden cardiac death in Athletes

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD), and coronary artery anomalies, each with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have emerged in Europe, where the Italian experience of mandatory annual screening of athletes has been the forerunner in efforts to identify individuals at risk. Ongoing clinical efforts are underway to help define the role of implantable cardioverter defibrillators as a preventive measure in appropriate candidates with HCM or ARVD, as well as methods to limit the potential for SCD as a result of chest blows sustained in sports and other recreational activities by means of chest protectors and special sporting equipment for young athletes.

Arrhythmogenic right-ventricular dysplasia/cardiomyopathy

PURPOSE OF REVIEW

Arrhythmogenic right-ventricular dysplasia is a rare inherited disease characterized by right-ventricular dysfunction and ventricular arrhythmias. The purpose of this article is to review recent developments concerning the diagnosis, genetics, and management of patients with this disease.

RECENT FINDINGS

In the past few years important new information has emerged regarding the role of magnetic resonance imaging in the diagnosis of arrhythmogenic right-ventricular dysplasia. Although magnetic resonance imaging is a very sensitive tool, it is also the most common reason for over diagnosis of this condition. There have also been important new breakthroughs in the genetic basis of arrhythmogenic right-ventricular dysplasia; it now appears that most forms result from mutations in genes encoding desmosomal junction proteins. This may explain why arrhythmogenic right-ventricular dysplasia preferentially impacts the thin right ventricle. Other studies have demonstrated the important role of implantable cardioverter defibrillator therapy in the management of patients with arrhythmogenic right-ventricular dysplasia. In the USA, most patients who meet the Task Force criteria for the disease undergo placement of an implantable cardioverter defibrillator for prevention of sudden cardiac death.

SUMMARY

Arrhythmogenic right-ventricular dysplasia is a rare disease. Recent new findings concerning the diagnosis and management of these patients should have direct implications regarding the evaluation and management of patients with this rare, but potentially life-threatening, disorder.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: screening, diagnosis, and treatment

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a heart muscle disorder characterized pathologically by fatty or fibrofatty replacement and electrical instability of the right ventricular myocardium. Clinical manifestations include structural and functional malformations (fatty infiltration, dilatation, aneurysms) of the right ventricle, ECG abnormalities, and presentation with ventricular tachycardias with left bundle branch block pattern or sudden death. The disease often is familial with an autosomal inheritance. The typical hallmarks of ARVD/C are distributed in the so-called "triangle of dysplasia." The functional and morphologic characteristics are relevant to clinical imaging approaches such as contrast angiography, echocardiography, radionuclide angiography, ultrafast computed tomography, and cardiovascular magnetic resonance imaging. Evident forms of the disease are straightforward to diagnose based on a series of diagnostic criteria proposed by the International Task Force for Cardiomyopathy. However, the diagnosis of early and mild forms of the disease often is difficult. Treatment is directed toward preventing life-threatening ventricular arrhythmias in which radiofrequency ablation and implantable defibrillators play an increasing role. Despite new diagnostic and therapeutic approaches in ARVD/C, uncertainties about the etiology of the disease, the genetic basis, the appropriate diagnosis and therapy, and the clinical course of patients with ARVD/C have resulted in several registries to increase our knowledge of this intriguing disease.

Arrhythmogenic right ventricular cardiomyopathy due to a novel plakophilin 2 mutation: wide spectrum of disease in mutation carriers within a family

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial disease, with male preponderance, characterized by progressive fibrofatty replacement of the right ventricle and ventricular arrhythmias. Mutations in plakophilin-2 (PKP2), a desmosomal protein, have been reported to underlie familial ARVC. We report a novel ARVC PKP2 mutation and present the clinical findings in three female mutation carriers.

METHODS

We sequenced PKP2 from genomic DNA isolated from peripheral blood lymphocytes in a female proband who presented with cardiac arrest and in her four first-degree relatives. Clinical testing and diagnosis of ARVC was based on International Task Force criteria.

RESULTS

The proband was diagnosed with ARVC due to right ventricular enlargement and regional hypokinesis, along with repolarization abnormalities and frequent ventricular ectopy. A novel 28 bp insertion in exon 11 of the PKP2 gene was found which causes a frameshift in the coding region. This results in a change in the amino acid sequence of the protein with a premature stop codon at position 740. Of the four relatives, only the mother and younger sister were identified as mutation carriers. The mother was phenotypically normal, while the younger sister has repolarization abnormalities and frequent ventricular ectopy.

CONCLUSIONS

We report a novel PKP2 mutation that causes familial ARVC. All mutation carriers in this kindred group were women, and the family showed incomplete penetrance and variable expression of ARVC. Premature truncation of the plakophilin-2 protein appears to be the predominant mechanism whereby PKP2 mutations elicit the ARVC phenotype.

Plakophilin-2 mutations are the major determinant of familial arrhythmogenic right ventricular dysplasia/cardiomyopathy

BACKGROUND

Mutations in the plakophilin-2 gene (PKP2) have been found in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC). Hence, genetic screening can potentially be a valuable tool in the diagnostic workup of patients with ARVC.

METHODS AND RESULTS

To establish the prevalence and character of PKP2 mutations and to study potential differences in the associated phenotype, we evaluated 96 index patients, including 56 who fulfilled the published task force criteria. In addition, 114 family members from 34 of these 56 ARVC index patients were phenotyped. In 24 of these 56 ARVC patients (43%), 14 different (11 novel) PKP2 mutations were identified. Four different mutations were found more than once; haplotype analyses revealed identical haplotypes in the different mutation carriers, suggesting founder mutations. No specific genotype-phenotype correlations could be identified, except that negative T waves in V(2) and V(3) occurred more often in PKP2 mutation carriers (P<0.05). Of the 34 index patients whose family members were phenotyped, 23 familial cases were identified. PKP2 mutations were identified in 16 of these 23 ARVC index patients (70%) with familial ARVC. On the other hand, no PKP2 mutations at all were found in 11 probands without additional affected family members (P<0.001).

CONCLUSIONS

PKP2 mutations can be identified in nearly half of the Dutch patients fulfilling the ARVC criteria. In familial ARVC, even the vast majority (70%) is caused by PKP2 mutations. However, nonfamilial ARVC is not related to PKP2. The high yield of mutational analysis in familial ARVC is unique in inherited cardiomyopathies.

Clinical features of arrhythmogenic right ventricular dysplasia/cardiomyopathy associated with mutations in plakophilin-2

BACKGROUND

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited cardiomyopathy characterized by right ventricular dysfunction and ventricular arrhythmias. A recent study reported mutations in PKP2, encoding the desmosomal protein plakophilin-2, associated with ARVD/C. The purpose of our study was to validate the frequency of PKP2 mutations in another large series of ARVD/C patients and to examine the phenotypic characteristics associated with PKP2 mutations.

METHODS AND RESULTS

DNA from 58 ARVD/C patients was sequenced to determine the presence of mutations in PKP2. Clinical features of ARVD/C were compared between 2 groups of patients: those with a PKP2 mutation and those with no detectable PKP2 mutation. Thirteen different PKP2 mutations were identified in 25 (43%) of the patients. Six of these mutations have not been reported previously; 4 occurred in multiple, apparently unrelated, families. The mean age at presentation was lower among those with a PKP2 mutation (28+/-11 years) than in those without (36+/-16 years) (P<0.05). The age at median cumulative symptom-free survival (32 versus 42 years) and at the median cumulative arrhythmia-free survival (34 versus 46 years) was lower among patients with a PKP2 mutation than among those without a PKP2 mutation (P<0.05). Inducibility of ventricular arrhythmias on an electrophysiology study, diffuse nature of right ventricular disease, and presence of prior spontaneous ventricular tachycardia were identified as predictors of implanted cardioverter/defibrillator (ICD) intervention only among patients without a PKP2 mutation (P<0.05).

CONCLUSIONS

Our study highlights the clinical relevance of PKP2 mutations in ARVD/C. Presence of a PKP2 mutation in ARVD/C correlates with earlier onset of symptoms and arrhythmia. Patients with a PKP2 mutation experience ICD interventions irrespective of the classic risk factors determining ICD intervention in ARVD/C patients.

Ventricular tachycardia in arrhythmogenic right ventricular dysplasia/cardiomyopathy: Clinical presentation, risk stratification and results of long-term follow-up

BACKGROUND

Not all patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) are at risk for sudden cardiac death. The aim of the study was to evaluate the risk stratification in patients with ARVD/C.

METHODS AND RESULTS

Programmed ventricular stimulation (PVS) was performed in 34 ARVD/C patients. Twenty-two, 7 and 4 patients had documented sustained monomorphic ventricular tachycardia (smVT), non-smVT and ventricular fibrillation, respectively. One patient experienced syncope only. An implantable cardioverter defibrillator (ICD) was implanted in 11 patients inducible in smVT with hemodynamic compromise, in 4 patients with documented ventricular fibrillation and in one patient with non-smVT (194 ms tachycardia cycle length) (ICD group, n = 16). Ten patients were left without any antiarrhythmic therapy, 5 patients received antiarrhythmic drugs and 3 patients underwent successful VT ablation (non-ICD group, n = 18). Thirteen patients had an abnormal signal averaged ECG. During 6.5 +/- 2.4 years 69% of ICD patients received appropriate discharges and one non-ICD patient had a hemodynamically tolerated smVT recurrence (no sudden cardiac death in both groups). Comparison between the cycle lengths of clinical VT, induced VT and follow-up VT revealed a strong relationship (R = 0.62-0.88). On multivariate analysis abnormal signal averaged ECG and decreased left ventricular ejection fraction were statistically significant predictors for VT recurrence.

CONCLUSIONS

In ARVD/C the tachycardia cycle length of clinical VT, PVS-induced VT and follow-up VT correlate well implicating that a PVS-guided approach does not provide additional information. Spontaneous arrhythmia in combination with clinical presentation allows identification of patients in need for an ICD.

Predictors of appropriate implantable defibrillator therapies in patients with arrhythmogenic right ventricular dysplasia

BACKGROUND

Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by ventricular arrhythmias and sudden cardiac death. The risk factors for sudden death and indications for implantable cardioverter-defibrillator (ICD) placement in patients with ARVD are not well defined.

OBJECTIVES

The purpose of this study was to determine which clinical and electrophysiologic variables best predict appropriate ICD therapies in patients with ARVD. Particular attention focused on whether the ICD was implanted for primary or second prevention.

METHODS

We enrolled 67 patients (mean age 36 +/- 14 years) with definite or probable ARVD who had undergone ICD placement. Appropriate ICD therapies were recorded, and Kaplan-Meier analysis was used to compare the event-free survival time between patients based upon the indication for ICD placement (primary vs secondary prevention), results of electrophysiologic testing, and whether the patient had probable or definite ARVD.

RESULTS

Over a mean follow-up of 4.4 +/- 2.9 years, 40 (73%) of 55 patients who met task force criteria for ARVD and 4 (33%) of 12 patients with probable ARVD had appropriate ICD therapies for ventricular tachycardia/ventricular fibrillation (VT/VF; P = .027). Mean time to ICD therapy was 1.1 +/- 1.4 years. Eleven of 28 patients who received an ICD for primary prevention (39%) and 33 of 35 patients who received an ICD for secondary prevention (85%) experienced appropriate ICD therapies (P = .001). Electrophysiologic testing did not predict appropriate ICD interventions in patients who received an ICD for primary prevention. Fourteen patients (21%) received ICD therapy for life-threatening (VT/VF >240 bpm) arrhythmias. There was no difference in the incidence of life-threatening arrhythmias in the primary and secondary prevention groups (P = .29).

CONCLUSION

Patients who meet task force criteria for ARVD are at high risk for sudden cardiac death and should undergo ICD placement for primary and secondary prevention, regardless of electrophysiologic testing results. Further research is needed to confirm that a low-risk subset of patients who may not require ICD placement can be identified.

Arrhythmogenic right ventricular dysplasia: a United States experience

BACKGROUND

Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by right ventricular dysfunction and ventricular arrhythmias. The purpose of our study was to describe the presentation, clinical features, survival, and natural history of ARVD in a large cohort of patients from the United States.

METHODS AND RESULTS

The patient population included 100 ARVD patients (51 male; median age at presentation, 26 [interquartile range {IQR}, 18 to 38; range, 2 to 70] years). A familial pattern was observed in 32 patients. The most common presenting symptoms were palpitations, syncope, and sudden cardiac death (SCD) in 27%, 26%, and 23% of patients, respectively. Among those who were diagnosed while living (n=69), the median time between first presentation and diagnosis was 1 (range, 0 to 37) year. During a median follow-up of 6 (IQR, 2 to 13; range, 0 to 37) years, implantable cardioverter/defibrillators (ICD) were implanted in 47 patients, 29 of whom received an appropriate ICD discharge, including 3 patients who received the ICD for primary prevention. At follow-up, 66 patients were alive, of whom 44 had an ICD in place, 5 developed signs of heart failure, 2 had a heart transplant, and 18 were on drug therapy. Thirty-four patients died either at presentation (n=23: 21 SCD, 2 noncardiac deaths) or during follow-up (n=11: 10 SCD, 1 of biventricular heart failure), of whom only 3 were diagnosed while living and 1 had an ICD implanted. On Kaplan-Meier analysis, the median survival in the entire population was 60 years.

CONCLUSIONS

ARVD patients present between the second and fifth decades of life either with symptoms of palpitations and syncope associated with ventricular tachycardia or with SCD. Diagnosis is often delayed. Once diagnosed and treated with an ICD, mortality is low. There is a wide variation in presentation and course of ARVD patients, which can likely be explained by the genetic heterogeneity of the disease.

[Right ventricular tachyarrhythmias--diagnostics and therapy]

Ventricular tachyarrhythmias originating from the right ventricle frequently occur in young, apparently healthy patients with rare underlying cardiac diseases. Among these are arrhythmogenic right ventricular cardiomyopathy (ARVC), idiopathic right ventricular outflow-tract tachycardia (RVOVT), and Brugada syndrome (BrS). All harbor the risk of sudden cardiac death, whereas they differ substantially as to diagnosis, therapy and prognosis. This is the reason why detailed investigations are an essential prerequisite for further efficient individualized management strategies which are mainly directed to prevent sudden cardiac death and to minimize the risk of arrhythmia recurrences in affected patients, respectively. Both antiarrhythmic drug therapy, catheter ablation, and the implantation of an automatic cardioverter defibrillator may, therefore, be a first-line therapeutic option in tailored treatment regimens. This review is a summary of the available literature on pathogenesis, diagnosis, treatment, and prognosis of such diseases associated with right ventricular tachyarrhythmias.

Arrhythmogenic right ventricular dysplasia/ cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a genetic cardiomyopathy characterized by ventricular arrhythmias and structural abnormalities of the right ventricle (RV). The most important aspect in the treatment of ARVD/C is establishing a correct diagnosis based on the International Task Force criteria. In our experience, cardiologists are not aware of these diagnostic criteria for ARVD/C and place too much importance on the results of magnetic resonance imaging of the RV. Patients with ARVD/C generally all have an abnormal 12-lead electrocardiogram, abnormal echocardiogram, and ventricular arrhythmias with a left bundle branch block morphology. If noninvasive testing suggests ARVD, invasive testing with an RV angiogram, RV biopsy, and electrophysiology study are recommended. We encourage patients to participate in the National Institutes of Health-sponsored multicenter clinical trial of ARVD/C (http://www.ARVD.comorhttp://www.ARVD.org). Once a diagnosis of ARVD/C is established, the main treatment decision involves whether to implant an implantable cardioverter-defibrillator (ICD). ICDs are recommended for patients who have experienced syncope, sudden death, or a sustained ventricular arrhythmia, and also for patients with overt evidence of ARVD, particularly if the electrophysiology study is abnormal or there is a family history of sudden death. We also recommend treatment of patients with ARVD/C with beta blockers and angiotensin-converting enzyme inhibitors, and that all patients with ARVD/C be screened for a mutation in the gene for plakophilin-2, because this is present in more than one third of patients with ARVD/C and may be helpful in the management of first-degree relatives.

Primary Prophylaxis of Sudden Death in Hypertrophic Cardiomyopathy, Arrhythmogenic Right Ventricular Cardiomyopathy, and Dilated Cardiomyopathy

We present an evidence-based overview of primary prevention of sudden cardiac death. Several recent studies have provided important data regarding pharmacologic and device-based therapy for patients with conditions that confer high risk for sudden death. A rational approach to these therapies, with emphasis on implanted cardiovertor defibrillators, is discussed.

Short- and long-term success of substrate-based mapping and ablation of ventricular tachycardia in arrhythmogenic right ventricular dysplasia

BACKGROUND

Multiple morphologies, hemodynamic instability, or noninducibility may limit ventricular tachycardia (VT) ablation in patients with arrhythmogenic right ventricular dysplasia (ARVD). Substrate-based mapping and ablation may overcome these limitations. We report the results and success of substrate-based VT ablation in ARVD.

METHODS AND RESULTS

Twenty-two patients with ARVD were studied. Traditional mapping for VT was limited because of multiple/changing VT morphologies (n=14), nonsustained VT (n=10), or hemodynamic intolerance (n=5). Sinus rhythm CARTO mapping was performed to define areas of "scar" (<0.5 mV) and "abnormal" myocardium (0.5 to 1.5 mV). Ablation was performed in "abnormal" regions, targeting sites with good pace maps compared with the induced VT(s). Linear lesions were created in these areas to (1) connect the scar/abnormal region to a valve continuity or other scar or (2) encircle the scar/abnormal region. Eighteen patients had implanted cardioverter defibrillators, 15 had implanted cardioverter defibrillator therapies, and 7 had sustained VT (6 with syncope). VTs (3+/-2 per patient) were induced (cycle length, 339+/-94 ms), and scar was identified in all patients. Scar areas were related to the tricuspid annulus, proximal right ventricular outflow tract, and anterior/inferior-apical walls. Lesions connected abnormal regions to the annulus (n=12) or other scars (n=4) and/or encircled abnormal regions (n=13). Per patient, a mean of 38+/-22 radiofrequency lesions was applied. Short-term success was achieved in 18 patients (82%). VT recurred in 23%, 27%, and 47% of patients after 1, 2, and 3 years' follow-up, respectively.

CONCLUSIONS

Substrate-based ablation of VT in ARVD can achieve a good short-term success rate. However, recurrences become increasingly common during long-term follow-up.

[Arrhythmogenic right ventricular dysplasia and sudden cardiac death]

ARVD manifests itself by a wide spectrum of clinical presentations from asymptomatic patients to a broad range of ventricular arrhythmia, extrasystoles, tachycardia, or sudden arrhythmic death which can be the first symptom. It is a major cause for sudden death in young people and sportsmen. In known ARVD the risk of sudden death is not easy to assess from the literature, as its natural history is modulated by the wide variety of antiarrhythmic therapies. Hemodynamically ill tolerated ventricular arrhythmia, left ventricular involvement, sports, a youger age below 35, and uncontrolled therapy seem to predict an adverse outcome for these patients. These data may be helpful to decide for an AICD.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy is recognized as an important cause of death in young patients, particularly athletes. In the past 5 years, cardiac MRI techniques have evolved rapidly in an attempt to improve the noninvasive diagnosis of this disorder. Steady-state free precession sequences and more rapid fat saturation techniques have permitted a comprehensive and well-tolerated examination. The first formal testing of diagnostic accuracy among a broad range of readers has recently been completed. Despite these advances, limited spatial resolution and interobserver variability have prevented successful implementation of these methods. Future approaches may include high-field imaging at 3 Tesla, and viability imaging to improve diagnostic accuracy.