Utility of SAECG in arrhythmogenic right ventricle dysplasia

A Comprehensive Review on the Electrocardiographic Manifestations of Cardiac Sarcoidosis: Patterns and Prognosis

PURPOSE OF REVIEW

Cardiac sarcoidosis (CS) refers to cardiac involvement in sarcoidosis and is usually associated with worse outcomes. This comprehensive review aims to elucidate the electrocardiographic (ECG) signs and features associated with CS, as well as examine modern techniques and their importance in CS evaluation.

RECENT FINDINGS

The exact pathogenesis of CS is still unclear, but it stems from an abnormal immunological response triggered by environmental factors in individuals with genetic predisposition. CS presents with non-cardiac symptoms; however, conduction system abnormalities are common in patients with CS. The most common electrocardiographic (ECG) signs include atrioventricular blocks and ventricular tachyarrhythmia. Distinct patterns, such as fragmented QRS complexes, T-wave alternans, and bundle branch blocks, are critical indicators of myocardial involvement. The application of advanced ECG techniques such as signal-averaged ECG, Holter monitoring, wavelet-transformed ECG, microvolt T-wave alternans, and artificial intelligence-supported analysis holds promising outcomes for opportune detection and monitoring of CS. Timely utilisation of inexpensive and readily available ECG possesses the potential to allow early detection and intervention for CS. The integration of artificial intelligence models into ECG analysis is a promising approach for improving the ECG diagnostic accuracy and further risk stratification of patients with CS.

Impact of the T-wave characteristics on distinguishing arrhythmogenic right ventricular cardiomyopathy from healthy children

BACKGROUND

T-wave inversion (TWI) is not considered useful for diagnosing pediatric arrhythmogenic right ventricular cardiomyopathy (ARVC), because right precordial TWI in ARVC resembles a normal juvenile pattern.

OBJECTIVES

The aims of this study were to clarify the electrocardiographic (ECG) characteristics of pediatric ARVC to distinguish those patients from healthy children.

METHODS

Between 1979 and 2017, 11 ARVC patients under 18 years old were registered and compared with school screening ECGs from 48,401 healthy children.

RESULTS

The mean age at the first arrhythmic event or diagnosis was 13.3 ± 4.7 years. Nine patients were asymptomatic initially and were found by ECG screening, but 6 developed severe symptoms during the follow-up. Healthy children had a normal juvenile pattern, while ARVC children, especially symptomatic patients, had a significant tendency to have inferior and anterior TWI. The phenomenon of T-wave discontinuity (TWD) in which the TWI became deeper from V1 to V3 and suddenly turned positive in V5 was significantly more frequent in ARVC (60%) than healthy children (0.55%). Anterior TWI and TWD were also significantly more frequent in those who developed severe symptoms. The sensitivity and specificity of TWD were 60% (95% CI, 31-83%), and 99% (95% CI, 99-99%) to distinguish ARVC from healthy children, as well as 100% (95% CI, 71-100%) and 80% (95% CI, 51-80%), respectively, to predict severe symptoms in the future.

CONCLUSIONS

The ECG is useful to distinguish ARVC children, even in the early phase. Anterior TWI and TWD could detect ARVC children and to predict the possible serious conditions.

Premature ventricular complexes: diagnostic and therapeutic considerations in clinical practice : A state-of-the-art review by the American College of Cardiology Electrophysiology Council

Premature ventricular complexes (PVCs) are common arrhythmias in the clinical setting. PVCs in the structurally normal heart are usually benign, but in the presence of structural heart disease (SHD), they may indicate increased risk of sudden death. High PVC burden may induce cardiomyopathy and left ventricular (LV) dysfunction or worsen underlying cardiomyopathy. Sometimes PVCs may be a marker of underlying pathophysiologic process such as myocarditis. Identification of PVC burden is important, since cardiomyopathy and LV dysfunction can reverse after catheter ablation or pharmacological suppression. This state-of-the-art review discusses pathophysiology, clinical manifestations, how to differentiate benign and malignant PVCs, PVCs in the structurally normal heart, underlying SHD, diagnostic procedures (physical examination, electrocardiogram, ambulatory monitoring, exercise testing, echocardiography, cardiac magnetic resonance imaging, coronary angiography, electrophysiology study), and treatment (lifestyle modification, electrolyte imbalance, medical, and catheter ablation).

Clinical Diagnosis, Imaging, and Genetics of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: JACC State-of-the-Art Review

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited cardiomyopathy that can lead to sudden cardiac death and heart failure. Our understanding of its pathophysiology and clinical expressivity is continuously evolving. The diagnosis of ARVC/D remains particularly challenging due to the absence of specific unique diagnostic criteria, its variable expressivity, and incomplete penetrance. Advances in genetics have enlarged the clinical spectrum of the disease, highlighting possible phenotypes that overlap with arrhythmogenic dilated cardiomyopathy and channelopathies. The principal challenges for ARVC/D diagnosis include the following: earlier detection of the disease, particularly in cases of focal right ventricular involvement; differential diagnosis from other arrhythmogenic diseases affecting the right ventricle; and the development of new objective electrocardiographic and imaging criteria for diagnosis. This review provides an update on the diagnosis of ARVC/D, focusing on the contribution of emerging imaging techniques, such as echocardiogram/magnetic resonance imaging strain measurements or computed tomography scanning, new electrocardiographic parameters, and high-throughput sequencing.

Epsilon wave: A review of historical aspects

The epsilon wave of the electrocardiogram (ECG) together with fragmented QRS (fQRS), the terminal conduction delay, incomplete right bundle branch block (IRBBB) and complete/advanced RBBB (CRBBB) of peripheral origin are part of a spectrum of ventricular depolarization abnormalities of arrhythmogenic cardiomyopathy(AC). Although the epsilon wave is considered a major diagnostic criterion for AC since 2010 (AC Task Force Criteria), its diagnostic value is limited because it is a sign of the later stage of the disease. It would be more appropriate to say that the epsilon wave is a “hallmark” of AC, but is of low diagnostic sensitivity. Although the epsilon wave has high specificity for AC, it can be present in other pathological conditions. In this update we will cover the nomenclature, association with disease states and electrocardiographic aspects of the epsilon wave.

Naxos disease: from the origin to today

Naxos disease, first described by Dr. Nikos Protonotarios and colleagues on the island of Naxos, Greece, is a special form of arrhythmogenic right ventricular dysplasia (ARVD). It is an inherited condition with a recessive form of transmission and a familial penetrance of 90%. It is associated with thickening of the skin of the hands and sole, and a propensity to woolly hair. The cardiac anomalies characterized by ventricular arrhythmias with ventricular extrasystoles and tachycardia and histologic features of the myocardium are consistent with ARVD, but in a more severe form of dysplasia with major dilatation of the right ventricle. The identification of the responsible first gene on chromosome 17, and its product plakoglobin as the responsible protein for Naxos disease proved to be a milestone in the study of ARVD, which opened a new field of research. Thanks to those with the determination to discover Naxos disease, there is and will be more clarity in understanding the mechanisms of juvenile sudden death in the young who have an apparently otherwise normal heart.

Value of a novel 16-lead High-Definition ECG machine to detect conduction abnormalities in structural heart disease

BACKGROUND

Depolarization abnormalities are hardly detectable by standard 12-lead electrocardiogram (ECG) in some patients.

OBJECTIVE

To evaluate the value of the 16-lead High-Definition (HD)-ECG machine to record conduction abnormalities including Epsilon waves in patients with structural heart disease.

METHODS

Tracings with 12-lead ECG, 16-lead HD-ECG, and signal-averaged ECG were studied.

RESULTS

(1) Case of severe coronary artery disease (CAD): On 16-lead HD-ECG, a tiny intra-QRS signal was noted in lead III, a prolonged P wave in lead II, and fragmentation on top of lead aVL and lead aVF. Proper automatic measurement of the prolonged P wave measuring 190 ms was noted. Signal-averaging by 16-lead HD-ECG in lead III showed the intra-QRS fragmentation and P wave prolongation of 180 ms. (2) First patient with arrhythmogenic right ventricular dysplasia (ARVD): Standard 12-lead ECG indicated Epsilon waves in lead III, V2, V3, and inverted T waves in V1-V3. 16-lead HD-ECG indicated QRS prolongation in lead II, III, aVL, aVF, V2, V3 as opposed to V6, and low amplitudes of QRS complexes in V4R and V3R as a new possible sign of ARVD. Notches in lead V2, widening of QRS complexes in all precordial leads, but shorter QRS in V8-V9 are also considered as a potential new diagnostic sign of ARVD. (3) Second ARVD patient: Notches at the end of the QRS in lead III and a negative initial deflection of the QRS in V1 and V2 were detected by standard 12-lead ECG. On 16-lead HD-ECG, a more pronounced QRS fragmentation was visible.

CONCLUSION

16-lead HD-ECG in both CAD and ARVD seems to be more sensitive than 12-lead ECG to record electrocardiographic abnormalities.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D)

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a progressive genetic cardiomyopathy characterized by progressive fatty and fibrous replacement of ventricular myocardium. The clinical presentation is marked by ventricular arrhythmias, some fatal. The disease has evolved from a primary electrical/electrophysiological disorder (in the 1980s-1990s) to a diagnostic imaging conundrum (in the 2000s) to the current day understanding of a genetic cardiomyopathy caused by defects in cell-cell adhesion proteins or intracellular signaling components. The pathogenesis, clinical presentation, and the genetics of the disease are discussed in this review.

Correlation between signal-averaged ECG and the histologic evaluation of the myocardial substrate in right ventricular outflow tract arrhythmias

BACKGROUND

The differential diagnosis between idiopathic and cardiomyopathy-related right ventricular outflow tract (RVOT) ventricular arrhythmias (VAs) is crucial. Signal-averaged ECG (SAECG) abnormalities are frequent in cardiomyopathy-related RVOT-VAs, although their pathophysiologic basis and diagnostic value in this setting are undefined. We tested the association between SAECG and the myocardial substrate underlying RVOT-VAs.

METHODS AND RESULTS

Twenty-four consecutive patients (median age, 50 years [42-59]; 12 men) with RVOT-VAs (10 with frequent [>1000/24 hours] premature ventricular contractions, 14 with ventricular tachycardias) underwent SAECG with 40-Hz filtering and electroanatomic mapping (EAM) with EAM-guided biopsy for characterization of the RVOT-VAs substrate. A filtered averaged QRS (fQRS) was obtained and analyzed for fQRS duration, low amplitude signal duration<40 mV (LAS40), and root-mean-square voltage in the last 40 ms of the QRS (RMS40). Standard definition of EAM scar was used. EAM-guided biopsy diagnosed ARVC in 11 (46%), myocarditis in 8 (33%), and idiopathic RVOT-VAs in 5 (21%) patients. Patients with cardiomyopathy-related RVOT-VAs had ≥1 EAM scar (median, 2 [1-2]; all with RVOT scar). EAM of patients with idiopathic RVOT-VAs was normal. Patients with cardiomyopathy-related RVOT-VAs had significantly longer fQRS (106 ms [92-132] versus 83 ms [82-84], P=0.01) and LAS40 (39 ms [36-51] versus 19 ms [18-21], P=0.02), and lower RMS40 (18 µV [9-26] versus 33 µV [32-33], P=0.04). A significant linear correlation was found between the extension (cm2) of the RVOT scar and all 3 SAECG parameters (rs=0.76, P<0.001 for the fQRSd; rs=0.73, P<0.001 for the LAS40; and rs=-0.72, P<0.001 for the RMS40). Using the established 2 of 3 criteria (ie, late potentials), SAECG diagnosed cardiomyopathy-related RVOT-VAs with high positive (100%) but low negative (38%) predictive values and missed 7 of 9 (78%) patients with RVOT scar<8 cm2.

CONCLUSIONS

In patients with RVOT-VAs, abnormal SAECG parameters reflect the presence of extensive cardiomyopathic involvement of the RVOT. However, a negative SAECG does not reliably rule out cardiomyopathy-related RVOT-VAs in the presence of a small RVOT scar.

Arrhythmogenic right ventricular dysplasia

OPINION STATEMENT

Arrhythmogenic right ventricular dysplasia (ARVD) is a genetic disorder that is characterized by ventricular arrhythmias and structural abnormalities of the right ventricle. Due to significant heterogeneity in its manifestation, the diagnosis of ARVD is challenging and requires a multifaceted approach to patient evaluation. It is important to not rush and diagnose ARVD prematurely, as the implications both for the patient and also for family members are enormous. Similarly, it is important for clinicians to be aware of this condition because it is potentially life threatening. There are three keys aspects to treatment once a diagnosis is established. The first issue concerns risk stratification and deciding whether to implant an implantable cardioverter defibrillator (ICD). We currently advise ICD implantation for probands who meet the full criteria for the disease, especially if they have experienced cardiac syncope, sustained ventricular tachycardia, or have severe right ventricular or left ventricular dysfunction. In addition, we feel there are sufficient observational clinical data and scientific data from animal models to advise that both competitive sports and high-level athletics be prohibited. We advise our patients to generally limit their activity to activities such as walking and golf. Finally, it is our opinion that most patients with ARVD should be treated with both a β-blocker as well as an angiotensin-converting enzyme inhibitor, provided these drugs are well tolerated.

Diagnostic utility of signal-averaged electrocardiography for detection of cardiac sarcoidosis

INTRODUCTION

Cardiac sarcoidosis (CS) occurs in up to 25% of patients with pulmonary involvement. Early diagnosis is critical because sudden death from ventricular arrhythmias can be the initial presentation. We sought to evaluate the diagnostic utility of signal-averaged ECG (SAECG) for detection of cardiac involvement of sarcoidosis.

METHODS

Subjects with biopsy proven sarcoidosis and symptoms suggestive of possible cardiac involvement were included in the cohort. Standard criteria for SAECG were used. Subjects were considered to have CS if they met criteria established by the Japanese Ministry of Health and Welfare modified to include cardiac MRI.

RESULTS

Of the 88 patients in the cohort 27 had evidence of CS independent of the SAECG results. The SAECG was abnormal in 14 of these 27 patients and 11 of the 61 of the subjects without cardiac involvement (P < 0.01). The sensitivity of SAECG detection of CS was 52% with a specificity of 82%. For the entire cohort, SAECG had a positive predictive value (PPV) of 0.56 and a negative predictive value (NPV) of 0.79. Within a subgroup of 67 patients with an unfiltered QRS duration of <100 ms, the specificity for diagnosing cardiac sarcoidosis improves to 100% with a reduced sensitivity of 36.8. Of the SAECG parameters, LAS40 was significantly associated with the diagnosis of cardiac sarcoidosis for the entire cohort (P < 0.01) and among the subgroup of patients with an unfiltered QRS duration of <100 ms (P < 0.01).

CONCLUSIONS

SAECG is a useful screening tool in the evaluation of sarcoidosis for detection of cardiac involvement.

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.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: a not so rare "disease of the desmosome" with multiple clinical presentations

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a rare but increasingly recognized form of a cardiomyopathy, involving primarily the right ventricle. Mutations in seven candidate genes coding for five desmosomal proteins (plakoglobin, plakophilin-2, desmoplakin, desmoglein-2, desmocollin-2), for the cardiac ryanodine receptor-2, for the transforming growth factor beta-3, and for the transmembrane protein 43, respectively, are pathogenetically important. A typical feature of the disease is the replacement of the right ventricular myocardium by fibrofatty infiltrates, leading to electrical instability including ventricular arrhythmias in the early stages, and reduced contractility and heart failure later on. The left ventricle may also be involved. Unfortunately, the disease is often diagnosed post mortem only, especially in young adults dying suddenly during exercise. Since the disease is inherited in up to 50% of cases, the screening of relatives is important. The implantable cardioverter defibrillator is an important therapeutic tool. Nevertheless, the mortality of the disease remains to be 2%-4% per year. Several clinical, electrocardiographic, and imaging parameters were identified as risk predictors for an adverse outcome. In this paper, we describe distinct clinical presentations of ARVC/D, review the genetic background of the disease, and discuss its diagnosis and treatment.

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.

The electrocardiogram as a prognostic tool for predicting major cardiac events

Among patients with cardiac disease, the identification of those who are at low risk and those who are at high risk for major cardiac events is crucial for a rational clinical management of individual patients. A correct noninvasive risk stratification of cardiac patients, in particular, has relevant clinical implications because it would avoid unnecessary exposure to potentially risky invasive diagnostic or interventional procedures in low-risk patients, whereas it would allow an appropriate aggressive diagnostic and therapeutic approach in high-risk patients. Furthermore, the appropriate identification of low- and high-risk patients would also have social and economic implications by favoring optimization of resource distribution and costs. A large number of studies in previous decades provided evidence that several methods and variables derived from the analysis of the electrocardiogram (ECG) are powerful predictors of major cardiac events in several clinical conditions. Despite that, there has been limited attention about how several of these findings can be used in clinical practice. Furthermore, in recent years, most studies about risk stratification of cardiac patients have mainly been focused on the use of a number of serum/plasma biomarkers with reduced attention to ECG variables. Surprisingly, however, there have been few attempts to establish whether the various proposed risk markers add any significant information to that obtainable from ECG methods. In this article, the evidence for the prognostic value of variables derived from the assessment of the ECG signal by several methods and techniques will be briefly reviewed. Because of the largeness of the topic, this review will be necessarily incomplete. Because most of the clinical research in this field concerned risk stratification of patients with coronary artery disease, the article will be largely focused on this population of patients. The role of ECG methods in specific cardiac diseases and, in particular, in the general population of asymptomatic subjects will be briefly discussed when believed appropriate and helpful. Furthermore, only major clinical events (ie, cardiac death, arrhythmic events, acute myocardial infarction) will be taken into account as end points in this article. Minor clinical events (eg, coronary revascularization procedures, coronary artery restenosis, recurrences of symptoms) are indeed less robust as end points because they are widely biased by subjective judgments.

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: 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.

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.

Misdiagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy

INTRODUCTION

Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) has major implications for the management of patients and their first-degree relatives. Diagnosis is based on a set of criteria proposed by the International Task Force for Cardiomyopathies. We report our experience in providing a re-evaluation for patients who previously have been diagnosed with ARVD/C.

METHODS AND RESULTS

We studied 89 patients who requested a re-evaluation for diagnosis of ARVD/C at our center. Each of these patients had been diagnosed with ARVD/C at their initial evaluation. Each patient was re-evaluated with clinical history, physical examination, and noninvasive testing at our center. Invasive testing, which included electrophysiologic testing, right ventricular angiography, and endomyocardial biopsy, was performed when clinically indicated. Sixty (92%) of the 65 patients who had undergone magnetic resonance imaging (MRI) at an outside institution were reported to have an abnormal MRI consistent with ARVD/C. Among these patients, the only abnormality identified was the qualitative finding of intramyocardial fat/wall thinning in 46 patients. On re-evaluation, these qualitative findings were not confirmed. None of these 46 patients ultimately were diagnosed with ARVD/C. Among the entire patient group, only 24 (27%) of the 89 patients met the Task Force criteria for ARVD/C.

CONCLUSION

This study demonstrates that the high frequency of "misdiagnosis" of ARVD/C is due to over-reliance on the presence of intramyocardial fat/wall thinning on MRI, incomplete diagnostic testing, and lack of awareness of the Task Force criteria. Diagnosis of ARVD/C cannot rely solely upon qualitative features on MRI.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by the patchy replacement of myocardium by fatty or fibrofatty tissue. These changes lead to structural abnormalities including right ventricular enlargement and wall motion abnormalities that can be detected by echocardiography, angiography, and cine MRI. ARVC/D is a genetically heterogeneous disorder, since it has been linked to several chromosomal loci. Myocarditis may also be a contributing etiological factor. Patients are typically diagnosed during adolescence or young adulthood. Presenting symptoms are generally related to ventricular arrhythmias. Concern for the risk of sudden cardiac death may lead to the implantation of an intracardiac defibrillator. An ongoing multicenter international registry should further our understanding of this disease.