Catheter ablation of stable and unstable ventricular tachycardias in patients with arrhythmogenic right ventricular dysplasia

Clinical outcomes of catheter ablation of ventricular tachycardia in patients with arrhythmogenic right ventricular cardiomyopathy: Insights from the Johns Hopkins ARVC Program

BACKGROUND

Previous studies of radiofrequency catheter ablation (RFA) of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), relying on limited numbers of procedures, have not reported VT-free survival in parallel for single and multiple procedures (ie, after the last procedure). Data regarding the impact of RFA on VT burden are scarce.

OBJECTIVE

The purpose of this study was to provide new insights on clinical outcomes based on a large series of VT ablation procedures from the current era in ARVC patients.

METHODS

We evaluated consecutive patients with definite ARVC who underwent RFA procedures between 2009 and 2019 at our center. We assessed VT-free survival, for single and multiple procedures, and changes in VT burden and antiarrhythmic drugs (AADs) after RFA.

RESULTS

Among 116 patients, there were 166 RFA procedures, 106 (63.9%) of which involved epicardial ablation. Cumulative freedom from VT after a single procedure was 68.6% and 49.8% at 1 and 5 years, respectively. Cumulative VT-free survival after multiple procedures was 81.8% and 69.6% at 1 and 5 years, respectively. VT burden per RFA was reduced after vs before ablation (mean 0.7 vs 10.0 events/year; P <.001). Furthermore, VT burden per patient was reduced after last ablation vs before first ablation (mean 0.5 vs 10.9 events/year; P <.001). Use of AADs decreased after ablation (22.2% vs 51.9%; P <.001).

CONCLUSION

In ARVC patients, RFA provided good VT-free survival after a single procedure, with multiple procedures required for more sustained freedom from VT recurrence. Marked reduction in VT burden permitted discontinuation of AADs.

Spatial and transmural properties of the reentrant ventricular tachycardia circuit in arrhythmogenic right ventricular cardiomyopathy: Simultaneous epicardial and endocardial recordings

BACKGROUND

While advances in the characterization of the structural substrate in arrhythmogenic right ventricular cardiomyopathy (ARVC) have been made, the ventricular tachycardia (VT) circuit remains incompletely described.

OBJECTIVE

The purpose of this study was to delineate the reentrant VT circuit with simultaneous epicardial and endocardial mapping (SEEM) in ARVC.

METHODS

Twenty-three consecutive patients with ARVC and VT underwent SEEM at 4 centers between 2014 and 2020. Retrospective analysis was performed on combined isochronal activation maps.

RESULTS

Of the 30 VT circuits, 24 were delineated with SEEM (956 [341-1843] endocardial points and 1763 [882-3054] epicardial points). The apex and outflow tract rarely harbored VT circuits, with 50% distributed in the inferior wall and 43% in the free wall. The entire tachycardia cycle length was recorded from the epicardium in 71% of circuits. In all circuits, a large proportion of the tachycardia cycle length was recorded from the epicardium relative to the endocardium. Localized epicardial reentry was observed in 35% of patients (14 mm × 15 mm), which was associated with smaller endocardial low voltage area (39 cm² vs 104 cm²; P = .002) and preserved right ventricular ejection fraction (35% vs 25%; P = .046) compared with those with larger circuit dimensions. Seventy percent of termination sites were achieved from the epicardium.

CONCLUSION

High-resolution recordings from both myocardial surfaces confirm a consistent predominance of epicardial participation during reentry in ARVC. Only the perivalvular inflow region of the "triangle of dysplasia" had a strong propensity to harbor VT circuits, with the greatest proportion located in the inferior wall. Localized epicardial reentry may be a manifestation of earlier stage disease with a relative paucity of endocardial substrate.

Re-entrant ventricular tachycardia as a complication of ablation of idiopathic ventricular premature beats from the right outflow tract: a case report

Background

We report an unusual case of non-sustained ventricular tachycardia (NSVT) from the epicardial part of the right ventricular outflow tract (RVOT).

Case summary

A 37-year-old woman who underwent in 2006 an ablation for idiopathic ventricular premature beats (VPBs) from the RVOT presented with pre-syncopal NSVT in 2016. A cardiac workup showed no coronary disease, normal biventricular function, and no enhancement on cardiac magnetic resonance imaging. A metabolic positron emission tomography scan excluded inflammation. Biopsies revealed normal desmosomal proteins. An endocardial mapping revealed an area of low voltage potential (<0.5 mV) at the antero-septal aspect of the RVOT corresponding to the initial site of ablation from 2006. Activation mapping revealed poor prematurity and pace-mapping showed unsatisfactory morphologies in the RVOT, the left ventricle outflow tract and the right coronary cusp. An epicardial map revealed a low voltage area at the antero-septal aspect of the RVOT with fragmented potentials opposite to the endocardial scar. Pace-mapping demonstrated perfect match. An NSVT was induced and local electrocardiogram showed mid-diastolic potentials. Ablation was applied epicardially and endocardially without any complication. The patient was arrhythmia free at 4-year follow-up.

Discussion

Cardiac workup allowed to exclude specific conditions such as arrhythmogenic cardiomyopathy, tetralogy of Fallot, sarcoidosis, or myocarditis as a cause for NSVT from the RVOT. The epi and endocardial map showed residual scar subsequent to the first ablation which served as substrate for the re-entrant NSVT. This is the first case which describes NSVT from the epicardial RVOT as a complication from a previous endocardial ablation for idiopathic VPB.

Ablation strategies for arrhythmogenic right ventricular cardiomyopathy: a systematic review and meta-analysis

Background

Catheter ablation for ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) has significantly evolved over the past decade. However, different ablation strategies showed inconsistency in acute and long-term outcomes.

Methods

We searched the databases of Medline, Embase and Cochrane Library through October 17, 2019 for studies describing the clinical outcomes of VT ablation in ARVC. Data including VT recurrence, all-cause mortality, acute procedural efficacy and major procedural complications were extracted. A meta-analysis with trial sequential analysis was further performed in comparative studies of endo-epicardial versus endocardial-only ablation.

Results

A total of 24 studies with 717 participants were enrolled. The literatures of epicardial ablation were mainly published after 2010 with total ICD implantation of 73.7%, acute efficacy of 89.8%, major complication of 5.2%, follow-up of 28.9 months, VT freedom of 75.3%, all-cause mortality of 1.1% and heart transplantation of 0.6%. Meta-analysis of 10 comparative studies revealed that compared with endocardial-only approach, epicardial ablation significantly decreased VT recurrence (OR: 0.50; 95% CI: 0.30-0.85; P = 0.010), but somehow increased major procedural complications (OR: 4.64; 95% CI: 1.28-16.92; P= 0.02), with not evident improvement of acute efficacy (OR: 2.74; 95% CI: 0.98-7.65; P = 0.051) or all-cause mortality (OR: 0.87; 95% CI: 0.09-8.31; P = 0.90).

Conclusion

Catheter ablation for VT in ARVC is feasible and effective. Epicardial ablation is associated with better long-term VT freedom, but with more major complications and unremarkable survival or acute efficacy benefit.

Catheter Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is predominantly an inherited cardiomyopathy with typical histopathological characteristics of fibro-fatty infiltration mainly involving the right ventricular (RV) inflow tract, RV outflow tract, and RV apex in the majority of patients. The above pathologic evolution frequently brings patients with ARVD/C to medical attention owing to the manifestation of syncope, sudden cardiac death (SCD), ventricular arrhythmogenesis, or heart failure. To prevent future or recurrent SCD, an implantable cardiac defibrillator (ICD) is highly desirable in patients with ARVD/C who had experienced unexplained syncope, hemodynamically intolerable ventricular tachycardia (VT), ventricular fibrillation, and/or aborted SCD. Notably, the management of frequent ventricular tachyarrhythmias in ARVD/C is challenging, and the use of antiarrhythmic drugs could be unsatisfactory or limited by the unfavorable side effects. Therefore, radiofrequency catheter ablation (RFCA) has been implemented to treat the drug-refractory VT in ARVD/C for decades. However, the initial understanding of the link between fibro-fatty pathogenesis and ventricular arrhythmogenesis in ARVD/C is scarce, the efficacy and prognosis of endocardial RFCA alone were limited and disappointing. The electrophysiologists had broken through this frontier after better illustration of epicardial substrates and broadly application of epicardial approaches in ARVD/C. In recent works of literature, the application of epicardial ablation also successfully results in higher procedural success and decreases VT recurrences in patients with ARVD/C who are refractory to the endocardial approach during long-term follow-up. In this article, we review the important evolution on the delineation of arrhythmogenic substrates, ablation strategies, and ablation outcome of VT in patients with ARVD/C.

Isolated Late Activation Detected by Magnetocardiography Predicts Future Lethal Ventricular Arrhythmic Events in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy

BACKGROUND

Risk stratification of ventricular arrhythmias is vital to the optimal management in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). We hypothesized that 64-channel magnetocardiography (MCG) would be useful to detect isolated late activation (ILA) by overcoming the limitations of conventional noninvasive predictors of ventricular tachyarrhythmias, including epsilon waves, late potential (LP), and right ventricular ejection fraction (RVEF), in ARVC patients.Methods and Results:We evaluated ILA on MCG, defined as discrete activations re-emerging after the decay of main RV activation (%magnitude >5%), and conventional noninvasive predictors of ventricular tachyarrhythmias (epsilon waves, LP, and RVEF) in 40 patients with ARVC. ILA was noted in 24 (60%) patients. Most ILAs were found in RV lateral or inferior areas (17/24, 71%). We defined "delayed ILA" as ILA in which the conduction delay exceeded its median (50 ms). During a median follow-up of 42.5 months, major arrhythmic events (MAEs: 1 sudden cardiac death, 3 sustained ventricular tachycardias, and 4 appropriate implantable cardioverter defibrillator discharges) occurred more frequently in patients with delayed ILA (6/12) than in those without (2/28; log-rank: P=0.004). Cox regression analysis identified delayed ILA as the only independent predictor of MAEs (hazard ratio 7.63, 95% confidence interval 1.72-52.6, P=0.007), and other noninvasive parameters were not significant predictors.

CONCLUSIONS

MCG is useful to identify ARVC patients at high risk of future lethal ventricular arrhythmias.

Heart Failure and Sudden Cardiac Death

The Centers for Diseases Control and Prevention estimates that 5.7 million adults in the United States suffer from heart failure and 1 in 9 deaths in 2009 cited heart failure as a contributing cause. Almost 50% of patients who are diagnosed with heart failure die within 5 years of diagnosis. Cardiovascular disease is a public health burden. The prognosis of patients with heart failure has improved significantly. However, the risk for death remains high. Managing sudden death risk and intervening appropriately with primary or secondary prevention strategies are of paramount importance.

Medical therapy to prevent recurrence of ventricular arrhythmia in normal and structural heart disease patients

INTRODUCTION

Recurrent ventricular arrhythmias (VA) are a source of significant morbidity in patients without structural heart disease (SHD) and also mortality in patients with SHD. The treatment goals for these two patient populations differ greatly. Areas covered: The secondary prevention of recurrent VA in patients without and with SHD will be reviewed, focusing on clinical data (especially randomized, controlled trials) in the literature as determined through searches in PubMed and ClinicalTrials.gov. This will include β blockers, non-dihydropyridine calcium channel blockers and antiarrhythmic drugs in both subgroups and non-antiarrhythmic medications in SHD. Expert commentary: The available options for medical therapy for VA in both normal hearts and SHD are insufficient, due to substandard efficacy and toxicities. While non-pharmacologic therapies may provide an excellent option, further drug development and randomized trials are needed, as is a reappraisal of the current mode of utilization.

Long-term outcomes of catheter ablation of ventricular tachycardia in patients with structural heart disease

BACKGROUND

Catheter ablation of ventricular tachycardia (VT) is feasible. However, the long-term outcomes for different underlying diseases have not been well defined.

METHODS

Eighty-eight consecutive patients who underwent catheter ablation of VT using a three-dimensional mapping system were analyzed. The primary endpoint was any VT or ventricular fibrillation (VF) recurrence. Secondary endpoints were a composite of death or any VT/VF recurrence. Underlying heart diseases were remote myocardial infarction (remote MI) in 51 patients and non-ischemic cardiomyopathy in 37 (arrhythmogenic right ventricular cardiomyopathy [ARVC] in 18 patients, and dilated cardiomyopathy [NIDCM] in 19).

RESULTS

Acute success was achieved in 82 of 88 (93%) patients. During a follow-up period of 39.2±4.6 months, VT recurred in 26 of 87 (30%), and VT/VF recurrence or death occurred in 39 of 87 (45%) patients. ARVC had better outcomes than NIDCM for the primary (p<0.05) and secondary endpoints (p<0.05). Remote MI-VT revealed a midrange outcome.

CONCLUSIONS

The long-term outcomes after catheter ablation of VT varied according to the underlying heart disease. ARVC-VT ablation was associated with better long-term prognosis than NIDCM. Remote MI-VT demonstrated a midrange outcome.

Treatment of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: An International Task Force Consensus Statement

Supplemental Digital Content is available in the text.

Contemporary Mapping Techniques of Complex Cardiac Arrhythmias - Identifying and Modifying the Arrhythmogenic Substrate

Cardiac electrophysiology has moved a long way forward during recent decades in the comprehension and treatment of complex cardiac arrhythmias. Contemporary electroanatomical mapping systems, along with state-of-the-art technology in the manufacture of electrophysiology catheters and cardiac imaging modalities, have significantly enriched our armamentarium, enabling the implementation of various mapping strategies and techniques in electrophysiology procedures. Beyond conventional mapping strategies, ablation of complex fractionated electrograms and rotor ablation in atrial fibrillation ablation procedures, the identification and modification of the underlying arrhythmogenic substrate has emerged as a strategy that leads to improved outcomes. Arrhythmogenic substrate modification also has a major role in ventricular tachycardia ablation procedures. Optimisation of contact between tissue and catheter and image integration are a further step forward to augment our precision and effectiveness. Hybridisation of existing technologies with a reasonable cost should be our goal over the next few years.

Right Ventricular Outflow Tract Arrhythmias: Benign Or Early Stage Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia?

Ventricular arrhythmias (VAs) arising from the right ventricular outflow tract (RVOT) are a common and heterogeneous entity. Idiopathic right ventricular arrhythmias (IdioVAs) are generally benign, with excellent ablation outcomes and long-term arrhythmia-free survival, and must be distinguished from other conditions associated with VAs arising from the right ventricle: the differential diagnosis with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is therefore crucial because VAs are one of the most important causes of sudden cardiac death (SCD) in young individuals even with early stage of the disease. Radiofrequency catheter ablation (RFCA) is a current option for the treatment of VAs but important differences must be considered in terms of indication, purposes and procedural strategies in the treatment of the two conditions. In this review, we comprehensively discuss clinical and electrophysiological features, diagnostic and therapeutic techniques in a compared analysis of these two entities.

Ventricular tachycardia mapping and ablation in arrhythmogenic right ventricular cardiomyopathy/dysplasia: Lessons Learned

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is primarily believed to be an inherited cardiomyopathy that subsequently results in significant myocardial fibrosis. The arrhythmogenic consequences that result from the development of fibrosis are similar to other nonischemic cardiomyopathies, but the unique endocardial-epicardial disease process of ARVC/D requires a specialized approach for arrhythmia treatment in the electrophysiology laboratory. Although the association between ARVC/D and development of ventricular arrhythmias has become increasingly clear over the last 2 decades, our understanding of the arrhythmia mechanisms, underlying electrophysiologic substrate, and treatment strategies were significantly limited. Prospective studies performed in the electrophysiology laboratory allowed detailed characterization of the electrophysiologic and electroanatomic substrate underlying ventricular tachycardia in patients with ARVC/D. This has allowed clinician scientists to better characterize the arrhythmia mechanism and develop the necessary strategies to perform successful catheter ablation. Early in this experience, catheter ablation was considered a limited and largely unsuccessful treatment for patients experiencing painful and recurrent defibrillator therapy. Through our increased understanding of the disease process, catheter ablation has evolved to become an effective and preferred therapy for a majority of these patients. Our understanding of the disease and necessary approaches to provide successful treatment continues to evolve as the clinical experience grows. This article will review these important insights from the electrophysiology laboratory and how application of this knowledge has facilitated the development of a methodical approach to successfully perform ventricular tachycardia ablation in patients with ARVC/D.

Predictors of success in ablation of scar-related ventricular tachycardia

During ablation of re-entrant ventricular tachycardia (VT) 3-dimensional mapping systems are now used to properly delineate the scar tissue and aid ablation of scar-related VT. The aim of our study was to outline how the mode of ablation predicts success and recurrence in large scar-related VT. When comparing patients with recurrence and patients with no recurrence, univariate analysis showed that number of ablation lesions (28 ± 8 vs. 12 ± 8, P = 0.01) and more linear ablation lesions rather than focal lesions (P = 0.03) were associated with long-term success. We demonstrated that more extensive ablation lesions and creation of linear lesions is associated with better success rate and lower recurrence rate during ablation of large scar-related ventricular tachycardia.

Epicardial ablation for ventricular tachycardia

Epicardial ablation has lately become a necessary tool to approach some ventricular tachycardias in different types of cardiomyopathy. Its diffusion is now limited to a few high volume centers not because of the difficulty of the pericardial puncture but since it requires high competence not only in the VT ablation field but also in knowing and recognizing the possible complications each of which require a careful treatment.

This article will review the state of the art of epicardial ablation with special attention to the procedural aspects and to the possible selection criteria of the patients

The Emerging Role of Epicardial Ablation

Sosa and colleagues first described a percutaneous approach (via the subxiphoid area) to access the pericardial space in 1996. Epicardial mapping and ablation is increasingly used for the treatment of supraventricular and ventricular arrhythmias and represents an adjunctive approach for challenging arrhythmias to improve procedural success rates. Epicardial ablation should be considered not only after the failure of an endocardial ablation but often as a first-line approach. Complications may occur during percutaneous access and epicardial ablation, and these might be reduced or avoided by improved operator skills and experience. New tools to access the epicardial space are being evaluated.

Outcomes of catheter ablation of ventricular tachycardia in arrhythmogenic right ventricular dysplasia/cardiomyopathy

BACKGROUND

Prior studies evaluating the efficacy of catheter ablation of ventricular tachycardia (VT) among patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) have reported varied outcomes. More recently, studies have suggested that an epicardial ablation is necessary for improved outcomes after catheter ablation of VT. The overall objective of the present study was to assess the efficacy of radiofrequency catheter ablation (RFA) of VT in ARVD/C, with particular focus on newer ablation strategies, including epicardial catheter ablation.

METHODS AND RESULTS

The study population included 87 patients with ARVD/C who underwent a total of 175 RFA procedures between 1992 and 2011 at 80 different electrophysiology centers. Recurrence of VT following RFA and effect of RFA on the burden of VT were assessed. The mean age of the cohort was 38±13 years. Over a mean follow-up of 88.3±66 months, the overall freedom from VT of the 175 procedures was 47%, 21%, and 15%, at 1, 5, and 10 years, respectively. The cumulative freedom from VT following epicardial RFA was 64% and 45% at 1 and 5 years, respectively, which was significantly longer than endocardial RFA (P=0.021). Survival free of VT among procedures with 3D electroanatomic mapping was significantly longer compared to those without (P=0.016). Burden of VT was reduced irrespective of the ablation strategy (P<0.001).

CONCLUSIONS

Although VT recurrences are common, RFA results in a significant reduction in the burden of VT in patients with ARVD/C. Further, although the use of 3D electroanatomic mapping systems and epicardial ablation strategies are associated with longer survival free of VT, recurrence rates remain considerable.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Role of catheter ablation of ventricular tachycardia associated with structural heart disease

In patients with structural heart disease, ventricular tachycardia (VT) worsens the clinical condition and may severely affect the short- and long-term prognosis. Several therapeutic options can be considered for the management of this arrhythmia. Among others, catheter ablation, a closed-chest therapy, can prevent arrhythmia recurrences by abolishing the arrhythmogenic substrate. Over the last two decades, different techniques have been developed for an effective approach to both tolerated and untolerated VTs. The clinical outcome of patients undergoing ablation has been evaluated in multiple studies. This editorial gives an overview of the role, methodology, clinical outcome and innovative approaches in catheter ablation of VT.

Ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy: arrhythmia-free survival after endo-epicardial substrate based mapping and ablation

BACKGROUND

In patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy, freedom from ventricular arrhythmias (VAs) after endocardial ablation is limited. We compared the long-term freedom from recurrent VAs by using endocardial-alone ablation versus endo-epicardial substrate-based ablation.

METHODS AND RESULTS

Forty-nine patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy undergoing ablation of ventricular tachycardia (VT) were divided into 2 groups: endocardial-alone ablation (group 1, n = 23) and endo-epicardial ablation (group 2, n = 26). All patients had an implantable cardioverter-defibrillator (ICD). Conventional and 3D mappings were used to determine the mechanism of induced VTs and to identify area of "scar" or "abnormal" myocardium. All critical sites responsible for VTs and points with "abnormal" potential were targeted for ablation from endocardium (group 1) or from both endocardium and epicardium (group 2). The procedural end point was noninducibility of sustained, monomorphic VT with isoproterenol. The presence of frequent premature ventricular contractions at the end of ablation was recorded. Patients were followed up by ECG, Holter, and ICD interrogation. After a follow-up of at least 3 years, freedom from VAs or ICD therapy was 52.2% (12/23) in group 1 and 84.6% (22/26) in group 2 (P = 0.029), with 21.7% (5/23) and 69.2% (18/26) patients off antiarrhythmic drugs (P < 0.001), respectively. Compared with patients with no premature ventricular contractions after ablation, patients with frequent premature ventricular contractions after ablation were more likely to have VA recurrence/ICD therapy [3/33 (9%) versus 12/16 (75%); log-rank P<0.001].

CONCLUSIONS

An endo-epicardial-based ablation strategy achieves higher long-term freedom from recurrent VAs off antiarrhythmic therapy in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy when compared with endocardial-alone ablation. The presence of ≥ 10 premature ventricular contractions per minute after ablation is associated with more VA recurrence.

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.

Lack of uniform progression of endocardial scar in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy and ventricular tachycardia

BACKGROUND

The endocardial substrate for ventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is thought to be caused by a progressive degenerative process. Many clinical decisions and treatment plans are guided by this pathophysiologic assumption, but the extent of progression of macroscopic endocardial scar and right ventricular (RV) dilatation have not been assessed.

METHODS AND RESULTS

Eleven patients with ARVD/C and ventricular tachycardia had 2 detailed sinus rhythm electroanatomic endocardial voltage maps (average, 291+/-122 points per map; range, 114 to 558 points) performed a mean of 57 months apart (minimum, 9 months) as part of ventricular tachycardia ablation procedures. Voltage-defined scar (<1.5 mV) and RV volume were measured by area and volume measurement software and compared. Two of the 11 patients had a clear increase in scar area (47 cm(2); 32 cm(2)) confirmed by visual inspection. The remaining 9 (81%; 95% CI, 48% to 98%) patients had no increase (<10-cm(2) difference) in scar area between studies. In contrast, 10 of the 11 patients had a significant increase in RV volume, with an average increase of 24% (212+/-67 mL to 263+/-52 mL; P< or =0.01).

CONCLUSIONS

In patients with ARVD/C and ventricular tachycardia, progressive RV dilatation is the rule, and rapid progression of significant macroscopic endocardial scar occurs in only a subset of patients. These results have important management implications, suggesting that efforts to prevent RV dilatation in this population are needed and that an aggressive substrate-based ablation strategy offers the potential to provide long-term ventricular tachycardia control.

Ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a genetically determined myocardial disease characterized by fibrofatty replacement of the right ventricular wall. Ventricular tachyarrhythmias can be seen in the early stages of the disease, which is one of the most important causes of sudden death in young healthy individuals. Radiofrequency (RF) catheter ablation is an option for the treatment of medically refractory ventricular arrhythmias and it has shown to successfully abolish recurrent ventricular tachycardias (VT) as well as reduce the frequency in defibrillator therapies. However, variable acute and long-term success rates have been reported. The current mapping and ablation techniques include activation and entrainment mapping during tolerated VT and substrate ablation using 3-dimensional electroanatomic mapping systems. This article aims at providing a comprehensive review of RF catheter ablation of ventricular arrhythmias in the context of ARVD.

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.

Evaluation and Management of Syncope

Context

Syncope is a commonly encountered by primary care physicians and cardiologists. Etiology is frequently not apparent, and patients may undergo unnecessary tests. Treatment must be tailored to the likely etiology. Complexities of diagnosis and treatment often warrant referral to a specialist.

Objective

To highlight the evolving recommendations for managing syncope in a clinically and cost effective manner.

Evidence Acquisition

An electronic literature search was undertaken of the Medline database from January 1996 to April 2006, using the Medical Subject Heading syncope, defibrillators, pacemakers, echocardiogram, cardiomyopathy, long QT syndrome, Arrhythmogenic right ventricular dysplasia, and Brugada syndrome. Abstracts and titles were reviewed to identify English-language trials. Bibliographies from the references as well as scientific statements from the Heart Rhythm Society, American Heart Association, and American College of Cardiology were reviewed.

Evidence Synthesis

A methodical approach to syncope can improve diagnosis, limit testing, and identify patients at risk of fatal outcome. A thorough history, physical exam and electrocardiogram are critical to the initial diagnosis. Presence of heart disease determines the extent of work-up and treatment. A trans-thoracic echocardiogram should be performed in patients with an unclear diagnosis and a positive cardiac history or an abnormal ECG. Ventricular arrhythmias are the most common cause of syncope in patients with structural heart disease. Patients with an ejection fraction less than 30 percent should receive an implantable defibrillator with few exceptions. An electrophysiology study may assist risk stratification in syncopal patients with borderline ventricular function. In patients without structural heart disease, the presence of a well defined arrhythmia syndrome consistent with a genetically determined risk of sudden death must be sought. The 12-lead electrocardiogram, family history and clinical presentation will identify most high-risk patients. Patients without structural heart disease can often be managed conservatively with well defined strategies for preventing neurocardiogenic syncope.

Conclusions

Managing syncope requires a methodical approach. An understanding of the limitations of the diagnostic tools and treatments is important. Lethal causes of syncope make it imperative to recognize the appropriate timing of referring patients to specialists.

Changes in the isolated delayed component as an endpoint of catheter ablation in arrhythmogenic right ventricular cardiomyopathy: predictor for long-term success

INTRODUCTION

Although successful ablation of ventricular tachycardia (VT) is feasible in arrhythmogenic right ventricular cardiomyopathy (ARVC), long-term recurrence is common. The aim of this study was to assess the usefulness of a change in the isolated delayed component (IDC) as an endpoint of the catheter ablation in ARVC.

METHODS AND RESULTS

Eighteen patients (48 +/- 11 years) with ARVC were studied. Detailed endocardial mapping of the right ventricle (RV) was performed during sinus rhythm. IDCs were recorded in 16 patients and the latest IDCs were related to the VT circuit. Catheter ablation was carried out in the areas with the IDCs. At the end of the session, the IDC was electrically dissociated in one, disappeared in five, exhibited second-degree block in one, was significantly delayed (>or=50 ms) in three, and remained unchanged in six. The change in the IDC was correlated with the change in the type II/III late potentials in the signal-averaged electrocardiography (ECG) and the inducibility of the clinical VT after the ablation. During a follow-up of 61 +/- 38 months, VT recurred in six. The patients with a changed IDC had a significantly lower VT recurrence than those with no IDC or an unchanged IDC (P < 0.02).

CONCLUSION

In patients with ARVC, (1) the IDCs during sinus rhythm are related to the clinical VT and can be a target for the ablation, (2) a change in the IDC can be used as an endpoint, and (3) qualitative analyses of the serial signal-averaged ECGs may be useful for the long-term follow-up.