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

Programmed Ventricular Stimulation: Risk Stratification and Guiding Antiarrhythmic Therapies

Electrophysiologic testing with programmed ventricular stimulation (PVS) has been utilized to induce ventricular tachycardia (VT), thereby improving risk stratification for patients with ischemic and nonischemic cardiomyopathies and determining the effectiveness of antiarrhythmic therapies, especially catheter ablation. A variety of procedural aspects can be modified during PVS in order to alter the sensitivity and specificity of the test including the addition of multiple baseline pacing cycle lengths, extrastimuli, and pacing locations. The definition of a positive result is also critically important, which has varied from exclusively sustained monomorphic VT (>30 seconds) to any ventricular arrhythmia regardless of morphology. In this review, we discuss the history of PVS and evaluate its role in sudden cardiac death risk stratification in a variety of patient populations. We propose an approach to future investigations that will capitalize on the unique ability to vary the sensitivity and specificity of this test. We then discuss the application of PVS during and following catheter ablation. The strategies that have been utilized to improve the efficacy of intraprocedural PVS are highlighted during a discussion of the limitations of this probabilistic strategy. The role of noninvasive programmed stimulation is also reviewed in predicting recurrent VT and informing management decisions including repeat ablations, modifications in antiarrhythmic drugs, and implantable cardioverter-defibrillator programming. Based on the available evidence and guidelines, we propose an approach to future investigations that will allow clinicians to optimize the use of PVS for risk stratification and assessment of therapeutic efficacy.

The role of fibrosis in cardiomyopathies: An opportunity to develop novel biomarkers of disease activity

Cardiomyopathies encompass a spectrum of heart disorders with diverse causes and presentations. Fibrosis stands out as a shared hallmark among various cardiomyopathies, reflecting a common thread in their pathogenesis. This prevalent fibrotic response is intricately linked to the consequences of dysregulated extracellular matrix (ECM) remodeling, emphasizing its significance in the development and progression the disease. This review explores the ECM involvement in various cardiomyopathies and its impact on myocardial stiffness and fibrosis. Additionally, we discuss the potential of ECM fragments as early diagnosis, prognosis, and risk stratification. Biomarkers deriving from turnover of collagens and other ECM proteins hold promise in clinical applications. We outline current clinical management, future directions, and the potential for personalized ECM-targeted therapies with specific focus on microRNAs. In summary, this review examines the role of the fibrosis in cardiomyopathies, highlighting the potential of ECM-derived biomarkers in improving disease management with implications for precision medicine.

Risk of malignant ventricular arrhythmias in patients with mildly to moderately reduced ejection fraction after permanent pacemaker implantation

BACKGROUND

Many patients with mildly to moderately reduced left ventricular ejection fraction (LVEF) who require permanent pacemaker (PPM) implantation do not have a concurrent indication for implantable cardioverter-defibrillator (ICD) therapy. However, the risk of ventricular tachycardia/ventricular fibrillation (VT/VF) in this population is unknown.

OBJECTIVE

The aim of this study was to describe the risk of VT/VF after PPM implantation in patients with mildly to moderately reduced LVEF.

METHODS

Retrospective analysis was performed of 243 patients with LVEF between 35% and 49% who underwent PPM placement and did not meet indications for an ICD. The primary end point was occurrence of sustained VT/VF. Competing risks regression was performed to calculate subhazard ratios for the primary end point.

RESULTS

Median follow-up was 27 months; 73% of patients were male, average age was 79 ± 10 years, average LVEF was 42% ± 4%, and 70% were New York Heart Association class II or above. Most PPMs were implanted for sick sinus syndrome (34%) or atrioventricular block (50%). Of 243 total patients, 11 (4.5%) met the primary end point of VT/VF. Multivessel coronary artery disease (CAD) was associated with significantly higher rates of VT/VF, with a subhazard ratio of 5.4 (95% CI, 1.5-20.1; P = .01). Of patients with multivessel CAD, 8 of 82 (9.8%) patients met the primary end point for an annualized risk of 4.3% per year.

CONCLUSION

Patients with mildly to moderately reduced LVEF and multivessel CAD undergoing PPM implantation are at increased risk for the development of malignant ventricular arrhythmias. Patients in this population may benefit from additional risk stratification for VT/VF and consideration for upfront ICD implantation.

Implantable cardioverter defibrillator use in arrhythmogenic right ventricular cardiomyopathy in North America and Europe

BACKGROUND AND AIMS

Implantable cardioverter-defibrillators (ICDs) are critical for preventing sudden cardiac death (SCD) in arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aims to identify cross-continental differences in utilization of primary prevention ICDs and survival free from sustained ventricular arrhythmia (VA) in ARVC.

METHODS

This was a retrospective analysis of ARVC patients without prior VA enrolled in clinical registries from 11 countries throughout Europe and North America. Patients were classified according to whether they received treatment in North America or Europe and were further stratified by baseline predicted VA risk into low- (<10%/5 years), intermediate- (10%-25%/5 years), and high-risk (>25%/5 years) groups. Differences in ICD implantation and survival free from sustained VA events (including appropriate ICD therapy) were assessed.

RESULTS

One thousand ninety-eight patients were followed for a median of 5.1 years; 554 (50.5%) received a primary prevention ICD, and 286 (26.0%) experienced a first VA event. After adjusting for baseline risk factors, North Americans were more than three times as likely to receive ICDs {hazard ratio (HR) 3.1 [95% confidence interval (CI) 2.5, 3.8]} but had only mildly increased risk for incident sustained VA [HR 1.4 (95% CI 1.1, 1.8)]. North Americans without ICDs were at higher risk for incident sustained VA [HR 2.1 (95% CI 1.3, 3.4)] than Europeans.

CONCLUSIONS

North American ARVC patients were substantially more likely than Europeans to receive primary prevention ICDs across all arrhythmic risk strata. A lower rate of ICD implantation in Europe was not associated with a higher rate of VA events in those without ICDs.

A case report of isolated arrhythmogenic left ventricular cardiomyopathy: phenotypes, diagnosis, and treatment

Background

Isolated arrhythmogenic left ventricular cardiomyopathy (IALVC) is a hereditary cardiomyopathy that is characterized by the replacement of left ventricular (LV) cardiomyocytes with fibrous and adipose tissue.

Case summary

A 55-year-old male patient presented with recurrent chest pain and palpitations characterized by episodes of monomorphic ventricular tachycardia and T-wave inversion. Coronary angiography was conducted to rule out myocardial ischaemia as the cause of chest pain. Echocardiography results revealed ventricular aneurysm formation at the apex of the left ventricle. Structural alterations of the cardiac magnetic resonance were consistent with the diagnosis of arrhythmogenic left ventricular cardiomyopathy with LV alterations without right ventricular involvement. Pathological staining of the lesion area further confirmed the diagnosis of IALVC. The TTN1 c.17617 C>A mutation in arrhythmogenic cardiomyopathy was identified using whole exome sequencing. His symptoms improved by the treatments including implantable cardioverter defibrillator (ICD) implantation, radiofrequency ablation, and ventricular aneurysm resection.

Discussion

The patient presented with IALVC with apical fibrofatty displacement and underwent surgical management, highlighting the importance of multimodal imaging, gene analysis, and histopathological findings for timely diagnosis, and emphasizing the benefits of life-saving therapy, including ICD implantation, radiofrequency ablation, and ventricular aneurysm resection. These findings contribute to a deeper understanding of the clinical presentation and outcome of IALVC.

The pivotal role of compelling high-risk electrocardiographic markers in prediction of ventricular arrhythmic risk in arrhythmogenic right ventricular cardiomyopathy: A systematic review and meta-analysis

INTRODUCTION

Several investigations have shown that existing risk stratification processes remain insufficient for stratifying sudden cardiac death risk in arrhythmogenic right ventricular cardiomyopathy (ARVC). Multiple auxiliary parameters are investigated to offer a more precise prognostic model. Our aim was to assess the association between several ECG markers (epsilon waves, prolonged terminal activation duration (TAD) of QRS, fragmented QRS (fQRS), late potentials on signal-averaged electrocardiogram (SA-ECG), T-wave inversion (TWI) in right precordial leads, and extension of TWI in inferior leads) with the risk of developing poor outcomes in ARVC.

METHODS

A systematic literature search from several databases was conducted until September 9th, 2023. Studies were eligible if it investigated the relationship between the ECG markers with the risk of developing ventricular arrhythmic events.

RESULTS

This meta-analysis encompassed 25 studies with a total of 3767 participants. Our study disclosed that epsilon waves, prolonged TAD of QRS, fQRS, late potentials on SA-ECG, TWI in right precordial leads, and extension of TWI in inferior leads were associated with the incremental risk of ventricular arrhythmias, implantable cardioverter-defibrillator shock, and sudden cardiac death, with the risk ratios ranging from 1.46 to 2.11. In addition, diagnostic test accuracy meta-analysis stipulated that the extension of TWI in inferior leads had the uppermost overall area under curve (AUC) value amidst other ECG markers apropos of our outcomes of interest.

CONCLUSION

A multivariable risk assessment strategy based on the previously stated ECG markers potentially enhances the current risk stratification models in ARVC patients, especially extension of TWI in inferior leads.

Prevention of Protease-Induced Degradation of Desmoplakin via Small Molecule Binding

Desmoplakin (DSP) is a large (~260 kDa) protein found in the desmosome, the subcellular structure that links the intermediate filament network of one cell to its neighbor. A mutation "hot-spot" within the NH2-terminal of the DSP protein (residues 299-515) is associated with arrhythmogenic cardiomyopathy. In a subset of DSP variants, disease is linked to calpain hypersensitivity. Previous studies show that calpain hypersensitivity can be corrected in vitro through the addition of a bulky residue neighboring the cleavage site, suggesting that physically blocking calpain accessibility is a viable strategy to restore DSP levels. Here, we aim to find drug-like molecules that also block calpain-dependent degradation of DSP. To do this, we screened ~2500 small molecules to identify compounds that specifically rescue DSP protein levels in the presence of proteases. We find that several molecules, including sodium dodecyl sulfate, palmitoylethanolamide, GW0742, salirasib, eprosarten mesylate, and GSK1838705A prevent wildtype and disease-variant-carrying DSP protein degradation in the presence of both trypsin and calpain without altering protease function. Computational screenings did not predict which molecules would protect DSP, likely due to a lack of specific DSP-drug interactions. Molecular dynamic simulations of DSP-drug complexes suggest that some long hydrophobic molecules can bind in a shallow hydrophobic groove that runs alongside the protease cleavage site. Identification of these compounds lays the groundwork for pharmacological treatment for individuals harboring these hypersensitive DSP variants.

Management of arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease characterised by fibrofatty replacement of the ventricular myocardium due to specific mutations, leading to ventricular arrhythmias and sudden cardiac death. Treating this condition can be challenging due to progressive fibrosis, phenotypic variations and small patient cohorts limiting the feasibility of conducting meaningful clinical trials. Although widely used, the evidence base for anti-arrhythmic drugs is limited. Beta-blockers are theoretically sound, yet their efficacy in reducing arrhythmic risk is not robust. Additionally, the impact of sotalol and amiodarone is inconsistent with studies reporting contradictory results. Emerging evidence suggests that combining flecainide and bisoprolol may be efficacious.Radiofrequency ablation has shown some potential in disrupting ventricular tachycardia circuits, with combined endo and epicardial ablation yielding better results which could be considered at the index procedure. In addition, stereotactic radiotherapy may be a future option that can decrease arrhythmias beyond simple scar formation by altering levels of Nav1.5 channels, Connexin 43 and Wnt signalling, potentially modifying myocardial fibrosis.Future therapies, such as adenoviruses and GSk3b modulation, are still in early-stage research. While implantable cardioverter-defibrillator implantation is a key intervention for reducing arrhythmic death, the risks of inappropriate shocks and device complications must be carefully considered.

Inherited Arrhythmias in the Pediatric Population: An Updated Overview

Pediatric cardiomyopathies (CMs) and electrical diseases constitute a heterogeneous spectrum of disorders distinguished by structural and electrical abnormalities in the heart muscle, attributed to a genetic variant. They rank among the main causes of morbidity and mortality in the pediatric population, with an annual incidence of 1.1-1.5 per 100,000 in children under the age of 18. The most common conditions are dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Despite great enthusiasm for research in this field, studies in this population are still limited, and the management and treatment often follow adult recommendations, which have significantly more data on treatment benefits. Although adult and pediatric cardiac diseases share similar morphological and clinical manifestations, their outcomes significantly differ. This review summarizes the latest evidence on genetics, clinical characteristics, management, and updated outcomes of primary pediatric CMs and electrical diseases, including DCM, HCM, arrhythmogenic right ventricular cardiomyopathy (ARVC), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), long QT syndrome (LQTS), and short QT syndrome (SQTS).

ICD outcome in pediatric arrhythmogenic cardiomyopathy

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is a very rare condition among pediatric patients. Sudden cardiac death (SCD) is the main complication and often requires ICD implantation. Aim of the study is the evaluation of the outcomes of ICD implanted ACM pediatric patients in terms of safety, efficacy and complications.

METHODS

All pediatric patients (<18 y.o.) diagnosed with ACM and who were implanted with ICD since 2009 in Our Institution were collected. Implantation was decided according to current recommendations/ guidelines, and outcome was recorded during follow-up.

RESULTS

Nineteen consecutive ACM patients were implanted with ICD. Subcutaneous ICDs (S-ICD) were implanted in 15 patients (79%) while transvenous ICDs (TV-ICD) in 4 patients (21%). Mean age at implantation was 14.3 ± 2.1 y.o. ICDs were implanted for secondary prevention in 4 (21%) patients, and for primary prevention in 15 (79%). During the follow-up (5.59 ± 3.4 years), appropriate ICD interventions were delivered in 4 (21%) patients for sustained VTs, [2 implanted in primary prevention (13%) and 2 in secondary prevention (50%)]. No defibrillation failures occurred. Inappropriate shocks occurred in 2 cases (10.5%). Device-related complications requiring device revision occurred in 3 (16%): lead dislodgement, surgical skin erosion and sensing defect.

CONCLUSIONS

In a pediatric ACM cohort, appropriate ICD therapies occurred in a minority of primary prevention patients and frequently in secondary prevention patients. The rate of inappropriate shocks and device-related complications were even more rare and mostly wound related. Therefore, ICD therapy in pediatric ACM is effective and safe.

Utility of Left and Right Ventricular Strain in Arrhythmogenic Right Ventricular Cardiomyopathy: A Prospective Multicenter Registry

BACKGROUND

Imaging evaluation of arrhythmogenic right ventricular cardiomyopathy (ARVC) remains challenging. Myocardial strain assessment by echocardiography is an increasingly utilized technique for detecting subclinical left ventricular (LV) and right ventricular (RV) dysfunction. We aimed to evaluate the diagnostic and prognostic utility of LV and RV strain in ARVC.

METHODS

Patients with suspected ARVC (n = 109) from a multicenter registry were clinically phenotyped using the 2010 ARVC Revised Task Force Criteria and underwent baseline strain echocardiography. Diagnostic performance of LV and RV strain was evaluated using the area under the receiver operating characteristic curve analysis against the 2010 ARVC Revised Task Force Criteria, and the prognostic value was assessed using the Kaplan-Meier analysis.

RESULTS

Mean age was 45.3±14.7 years, and 48% of patients were female. Estimation of RV strain was feasible in 99/109 (91%), and LV strain was feasible in 85/109 (78%) patients. ARVC prevalence by 2010 ARVC Revised Task Force Criteria is 91/109 (83%) and 83/99 (84%) in those with RV strain measurements. RV global longitudinal strain and RV free wall strain had diagnostic area under the receiver operating characteristic curve of 0.76 and 0.77, respectively (both P<0.001; difference NS). Abnormal RV global longitudinal strain phenotype (RV global longitudinal strain > -17.9%) and RV free wall strain phenotype (RV free wall strain > -21.2%) were identified in 41/69 (59%) and 56/69 (81%) of subjects, respectively, who were not identified by conventional echocardiographic criteria but still met the overall 2010 ARVC Revised Task Force Criteria for ARVC. LV global longitudinal strain did not add diagnostic value but was prognostic for composite end points of death, heart transplantation, or ventricular arrhythmia (log-rank P=0.04).

CONCLUSIONS

In a prospective, multicenter registry of ARVC, RV strain assessment added diagnostic value to current echocardiographic criteria by identifying patients who are missed by current echocardiographic criteria yet still fulfill the diagnosis of ARVC. LV strain, by contrast, did not add incremental diagnostic value but was prognostic for identification of high-risk patients.

Incidence, risk assessment and prevention of sudden cardiac death in cardiomyopathies

Cardiomyopathies are a significant contributor to cardiovascular morbidity and mortality, mainly due to the development of heart failure and increased risk of sudden cardiac death (SCD). Despite improvement in survival with contemporary treatment, SCD remains an important cause of mortality in cardiomyopathies. It occurs at a rate ranging between 0.15% and 0.7% per year (depending on the cardiomyopathy), which significantly surpasses SCD incidence in the age- and sex-matched general population. The risk of SCD is affected by multiple factors including the aetiology, genetic basis, age, sex, physical exertion, the extent of myocardial disease severity, conduction system abnormalities, and electrical instability, as measured by various metrics. Over the past decades, the knowledge on the mechanisms and risk factors for SCD has substantially improved, allowing for a better-informed risk stratification. However, unresolved issues still challenge the guidance of SCD prevention in patients with cardiomyopathies. In this review, we aim to provide an in-depth discussion of the contemporary concepts pertinent to understanding the burden, risk assessment and prevention of SCD in cardiomyopathies (dilated, non-dilated left ventricular, hypertrophic, arrhythmogenic right ventricular, and restrictive). The review first focuses on SCD incidence in cardiomyopathies and then summarizes established and emerging risk factors for life-threatening arrhythmias/SCD. Finally, it discusses validated approaches to the risk assessment and evidence-based measures for SCD prevention in cardiomyopathies, pointing to the gaps in evidence and areas of uncertainties that merit future clarification.

Risk of cardioembolic ischemic events and relation to atrial fibrillation/flutter in patients with arrhythmogenic cardiomyopathy during a long-term follow-up

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease characterized by fibro-fatty replacement of myocardium. Limited data is available concerning cardioembolic stroke. This study sought to determine the occurrence of cardioembolic ischemic events (CIEs) in ACM patients and to identify clinical and imaging predictors of CIEs.

METHODS

Every consecutive ACM patient was enrolled. ECG, Holter monitoring or implantable cardiac devices were used to detect atrial arrhythmias (AAs). CIEs were defined according to TOAST classification.

RESULTS

In our cohort of 111 patients, CIEs were observed in eleven (10%) over a 12.9-year median follow-up, with an incidence of 7.9 event/1000 patient-year (HR 4.12 compared to general population). Mean age at the event was 42 ± 9 years. Female sex (p = 0.03), T-wave inversion (p = 0.03), RVOT dilatation (p = 0.006) and lower LVEF (p = 0.006) were associated with CIEs. Among patients with AAs (23/111, 20.7%), 5 (21.7%) experienced CIEs. CHA2DS2-VASc did not prove useful to define patients at higher risk of CIEs (p = 0.098). 60% of stroke suffering patients had a pre-event score between 0 and 1 (if female).

CONCLUSIONS

In ACM patients, CIEs are much more common than in general population and present a high burden at younger age. AAs relate to less than half of these events. In AAs patients, CHA2DS2-VASc is not useful to stratify those requiring oral anticoagulation. As a hypothesis-generating study, our research proposes the role of atrial myopathy, irrespective of AAs, as a pivotal factor in thrombogenesis risk, pointing out a definite unmet need in ACM therapeutic algorithm.

Arrhythmogenic Cardiomyopathy: Evolving Diagnostic Criteria and Insight from Cardiac Magnetic Resonance Imaging

Arrhythmogenic cardiomyopathy (ACM) is an umbrella term encompassing a wide variety of overlapping hereditary and nonhereditary disorders that can result in malignant ventricular arrhythmias and sudden cardiac death. Cardiac MRI plays a critical role in accurate diagnosis of various ACM entities and is increasingly showing promise in risk stratification that can further guide management particularly in decisions regarding use of implantable cardioverter defibrillator. Genotyping plays an important role in cascade testing but challenges remain due to incomplete penetrance and wide phenotypic variability of ACM as well as the presence of gene-elusive cases.

Prevention of Sudden Death and Management of Ventricular Arrhythmias in Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy is an umbrella term for a group of inherited diseases of the cardiac muscle characterized by progressive fibro-fatty replacement of the myocardium. As suggested by the name, the disease confers electrical instability to the heart and increases the risk of the development of life-threatening arrhythmias, representing one of the leading causes of sudden cardiac death (SCD), especially in young athletes. In this review, the authors review the current knowledge of the disease, highlighting the state-of-the-art approaches to the prevention of the occurrence of SCD.

cAMP: A master regulator of cadherin-mediated binding in endothelium, epithelium and myocardium

Regulation of cadherin-mediated cell adhesion is crucial not only for maintaining tissue integrity and barrier function in the endothelium and epithelium but also for electromechanical coupling within the myocardium. Therefore, loss of cadherin-mediated adhesion causes various disorders, including vascular inflammation and desmosome-related diseases such as the autoimmune blistering skin dermatosis pemphigus and arrhythmogenic cardiomyopathy. Mechanisms regulating cadherin-mediated binding contribute to the pathogenesis of diseases and may also be used as therapeutic targets. Over the last 30 years, cyclic adenosine 3',5'-monophosphate (cAMP) has emerged as one of the master regulators of cell adhesion in endothelium and, more recently, also in epithelial cells as well as in cardiomyocytes. A broad spectrum of experimental models from vascular physiology and cell biology applied by different generations of researchers provided evidence that not only cadherins of endothelial adherens junctions (AJ) but also desmosomal contacts in keratinocytes and the cardiomyocyte intercalated discs are central targets in this scenario. The molecular mechanisms involve protein kinase A- and exchange protein directly activated by cAMP-mediated regulation of Rho family GTPases and S665 phosphorylation of the AJ and desmosome adaptor protein plakoglobin. In line with this, phosphodiesterase 4 inhibitors such as apremilast have been proposed as a therapeutic strategy to stabilize cadherin-mediated adhesion in pemphigus and may also be effective to treat other disorders where cadherin-mediated binding is compromised.

Arrhythmogenic Right Ventricular Cardiomyopathy With Extensive Abnormal Substrate: Is Isolation Possible?

BACKGROUND

In arrhythmogenic right ventricular cardiomyopathy (ARVC) patients with extensive right ventricular free wall (RVFW) abnormal substrate, large-area homogenization with combined epicardial and endocardial approach is time consuming and often inadequate for modification.

OBJECTIVES

This study aimed to explore the feasibility and efficacy of RVFW abnormal substrate isolation in such patients to control ventricular tachycardia (VT).

METHODS

Eight consecutive ARVC patients with VT who had extensive abnormal RVFW substrate were included. VT induction was performed before substrate mapping and modification. Detailed voltage mapping was done during sinus rhythm. A circumferential linear lesion was deployed along the border zone of low-voltage area on the RVFW to achieve electrical isolation. Other small areas with fractionated or late potentials were further homogenized.

RESULTS

All 8 patients had RVFW endocardial low-voltage area. The entire RV low-voltage area was 113.8 ± 84.1 cm2 (49.6% ± 29.8%) and the dense scar was 59.6 ± 39.8 cm2 (25.0% ± 14.1%). Electrical isolation of abnormal substrate was achieved in 5 of 8 (62.5%) patients via endocardial approach alone and 3 of 8 (37.5%) patients via a combination of endocardial and epicardial approach. Electrical isolation was verified by slow automaticity (5 of 8, 62.5%) or RV noncapture (3 of 8, 37.5%) during high-output pacing inside the encircled area. VTs were induced in 6 patients before ablation, and all patients were rendered noninducible after ablation. During a median follow-up of 43 months (range: 24-53 months), 7 of 8 (87.5%) patients remained free of sustained VT.

CONCLUSIONS

Electrical isolation of RVFW is feasible and can be the option in ARVC patients with extensive abnormal substrate.

T-wave Inversions in Precordial Leads: A Case Study of Arrhythmogenic Right Ventricular Cardiomyopathy in a Patient With Recurrent Syncope

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare sudden cardiac death (SCD) syndrome characterized by ventricular arrhythmias of right ventricular (RV) origin. This case follows the presentation of ARVC in an otherwise healthy 26-year-old male. The patient was observed for one week after being admitted from the emergency department secondary to pre-syncope with pathognomonic findings on his electrocardiogram (EKG), echocardiogram, and cardiac imaging. The patient was started on beta-blockers, which ultimately he could not tolerate due to bradycardia, and the recommendation of an automatic implantable cardioverter-defibrillator (AICD) was refused. He was discharged without any complications or ventricular arrhythmias on telemetry while hospitalized.

Development of the Implantable Cardioverter-Defibrillator: JACC Historical Breakthroughs in Perspective

Implantable cardioverter-defibrillators (ICDs) represent transformational technology, arguably the most significant advance in cardiovascular medicine in 50 years. The vision and determination of pioneers Mirowski and Mower was fundamental to this monumental achievement, working with limited resources and confronted by skepticism/criticism from medical establishment. The inventors were followed >35 years in which a multitude of innovative clinical scientists and engineers introduced technological advances leading to the sophisticated devices in practice today. A pivotal patient experiment with automated termination of ventricular fibrillation (1980) led to U.S. Food and Drug Administration approval. Transvenous lead systems converted ICDs from thoracotomy-based secondary prevention to primary prevention of sudden death devices in countless patients worldwide. ICD acceptance was solidified by prospective randomized controlled trials showing reduced mortality superior to antiarrhythmic drugs. ICDs eventually expanded from coronary disease to inherited arrhythmia conditions (eg, hypertrophic cardiomyopathy). The ICD breakthrough story demonstrates how significant progress is possible in medicine against all odds, given fearless imagination to pursue novel ideas that conflict with accepted wisdom.

Individualized Family Screening for Arrhythmogenic Right Ventricular Cardiomyopathy

BACKGROUND

Clinical guidelines recommend regular screening for arrhythmogenic right ventricular cardiomyopathy (ARVC) to monitor at-risk relatives, resulting in a significant burden on clinical resources. Prioritizing relatives on their probability of developing definite ARVC may provide more efficient patient care.

OBJECTIVES

The aim of this study was to determine the predictors and probability of ARVC development over time among at-risk relatives.

METHODS

A total of 136 relatives (46% men, median age 25.5 years [IQR: 15.8-44.4 years]) from the Netherlands Arrhythmogenic Cardiomyopathy Registry without definite ARVC by 2010 task force criteria were included. Phenotype was ascertained using electrocardiography, Holter monitoring, and cardiac imaging. Subjects were divided into groups with "possible ARVC" (only genetic or familial predisposition) and "borderline ARVC" (1 minor task force criterion plus genetic or familial predisposition). Cox regression was performed to determine predictors and multistate modeling to assess the probability of ARVC development. Results were replicated in an unrelated Italian cohort (57% men, median age 37.0 years [IQR: 25.4-50.4 years]).

RESULTS

At baseline, 93 subjects (68%) had possible ARVC, and 43 (32%) had borderline ARVC. Follow-up was available for 123 relatives (90%). After 8.1 years (IQR: 4.2-11.4 years), 41 (33%) had developed definite ARVC. Independent of baseline phenotype, symptomatic subjects (P = 0.014) and those 20 to 30 years of age (P = 0.002) had a higher hazard of developing definite ARVC. Furthermore, patients with borderline ARVC had a higher probability of developing definite ARVC compared with those with possible ARVC (1-year probability 13% vs 0.6%, 3-year probability 35% vs 5%; P < 0.01). External replication showed comparable results (P > 0.05).

CONCLUSIONS

Symptomatic relatives, those 20 to 30 years of age, and those with borderline ARVC have a higher probability of developing definite ARVC. These patients may benefit from more frequent follow-up, while others may be monitored less often.

Arrhythmogenic Left Ventricular Cardiomyopathy Associated With a Phospholamban Gene Mutation in a Young Female: A Case Report and Literature Review

Arrhythmogenic cardiomyopathy (ACM) is a myocardium disease characterized by phenotypic features of myocardial scarring due to fibrofatty myocardial replacement often associated with global or regional ventricular dysfunction. For years after arrhythmogenic right ventricular cardiomyopathy (ARVC) was first described, the left ventricle (LV) was generally considered normal or minimally involved. In recent years, however, LV involvement has been recognized. It usually presents with early-on arrhythmias more than heart failure symptoms compared to dilated cardiomyopathy. It can be right ventricular, biventricular, or left ventricular. The underlying pathophysiology involves either desmosomal or non-desmosomal mutations. Phospholamban (PLN) mutation is one of those and is associated with more severe arrhythmias and SCD. Primary prevention with ICD implantation should be considered in these patients, even the ones with an ejection fraction greater than 35%. In addition, if such patients progress to Stage D heart failure, they need to be evaluated for advanced heart failure therapies.

Application of next generation sequencing in cardiology: current and future precision medicine implications

Inherited cardiovascular diseases are highly heterogeneous conditions with multiple genetic loci involved. The application of advanced molecular tools, such as Next Generation Sequencing, has facilitated the genetic analysis of these disorders. Accurate analysis and variant identification are required to maximize the quality of the sequencing data. Therefore, the application of NGS for clinical purposes should be limited to laboratories with a high level of technological expertise and resources. In addition, appropriate gene selection and variant interpretation can result in the highest possible diagnostic yield. Implementation of genetics in cardiology is imperative for the accurate diagnosis, prognosis and management of several inherited disorders and could eventually lead to the realization of precision medicine in this field. However, genetic testing should also be accompanied by an appropriate genetic counseling procedure that clarifies the significance of the genetic analysis results for the proband and his family. In this regard, a multidisciplinary collaboration among physicians, geneticists, and bioinformaticians is imperative. In the present review, we address the current state of knowledge regarding genetic analysis strategies employed in the field of cardiogenetics. Variant interpretation and reporting guidelines are explored. Additionally, gene selection procedures are accessed, with a particular emphasis on information concerning gene-disease associations collected from international alliances such as the Gene Curation Coalition (GenCC). In this context, a novel approach to gene categorization is proposed. Moreover, a sub-analysis is conducted on the 1,502,769 variation records with submitted interpretations in the Clinical Variation (ClinVar) database, focusing on cardiology-related genes. Finally, the most recent information on genetic analysis's clinical utility is reviewed.

Arrhythmogenic Cardiomyopathy and Athletes - A Dangerous Relationship

Arrhythmogenic cardiomyopathy (ACM) is a disease characterized by a progressive replacement of myocardium by fibro-adipose material, predisposing to ventricular arrhythmias (VA) and sudden cardiac death (SCD). Its prevalence is estimated at 1:2000 to 1:5000, with a higher incidence in males, and clinical onset is usually between the 2nd and 4th decade of life. The prevalence of ACM in SCD victims is relatively high, making it one of the most common etiologies in young patients with SCD, especially if they are athletes. Cardiac events occur more frequently in individuals with ACM who participate in competitive sports and/or high-intensity training. In effect, exercise activity can worsen RV function in cases of hereditary ACM. Estimating the incidence of SCD caused by ACM in athletes remains challenging, being reported frequency ranging from 3-20%. Here, we review the potential implications of exercising on the clinical course of the classical genetic form of ACM, as well as the diagnostic tools, risk stratification, and the different therapeutic tools available for managing ACM.

Electrocardiogram in arrhytmogenic cardiomyopathy

Criteria for diagnosis of arrhythmogenic cardiomyopathy (ACM) were first proposed in 1994 and subsequently revised in 2010 and in 2020 by an international task force. According to the last consensus of 2020, ACM is defined as a heart muscle disease affecting right ventricle, left ventricle or both, whose principal pathologic feature is fibrofatty myocardial replacement that impairs systolic ventricular function and predisposes to lethal ventricular arrhythmias. ECG findings not only could help to early recognize affected patients but also could identify the ones with maximum risk of ventricular arrhythmias and sudden cardiac death.

Antiarrhythmic Drug Therapy in Arrhythmogenic Right Ventricular Cardiomyopathy

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

Third-generation subcutaneous implantable cardioverter defibrillator and intermuscular two-incision implantation technique in patients with Arrhythmogenic cardiomyopathy: 3-year follow-up

BACKGROUND

Long-term data on the potential advantages of combining the third-generation subcutaneous implantable cardioverter defibrillator (S-ICD) with modern software upgrade including the "SMART Pass", modern programming strategies and the intermuscular (IM) two-incision implantation technique in arrhythmogenic cardiomyopathy (ACM) with different phenotypic variants are lacking. In this study we evaluated the long-term outcome of patients with ACM who underwent third-generation S-ICD (Emblem, Boston Scientific) and IM two-incision technique.

METHODS

The study population included 23 consecutive patients [70% male, median age 31 (24-46) years] diagnosed with ACM with different phenotypic variants who received third-generation S-ICD implantation with the IM two-incision technique.

RESULTS

During a median follow-up of 45.5 months [16-65], 4 patients (17.4%) received a at least one inappropriate shock (IS), with median annual event rate of 4.5%. Extra-cardiac oversensing (myopotential) during effort represented the only cause of IS. No IS due to T-wave oversensing (TWOS) were recorded. Only one patient (4.3%) experienced device-related complication consisting of premature cell battery depletion requiring device replacement. No device explantation because of need for anti-tachycardia pacing or ineffective therapy occurred. There was no significant difference between patients who did and did not experienced IS with regard to baseline clinical, ECG and technical characteristics. Five patients (21.7%) received appropriate shock on ventricular arrythmias.

CONCLUSIONS

According to our finding, although the third-generation S-ICD implanted with the IM two-incision technique appears to be associated with a low risk of complications and IS due to cardiac oversensing, the risk of IS due to myopotential mainly during effort should be considered.

Diagnosis and management of arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disorder of the myocardium that can lead to ventricular arrhythmia and sudden cardiac death. The condition has been identified as a significant cause of arrhythmic death among young people and athletes, therefore, early recognition of the disease by emergency clinicians is critical to prevent subsequent death. The diagnosis of ARVC can be very challenging and requires a systematic approach. This publication reviews the pathophysiology, classification, clinical presentations, and appropriate approach to diagnosis and management of ARVC.

Clinical Features, Genetic Findings, and Risk Stratification in Arrhythmogenic Right Ventricular Cardiomyopathy: Data From a Brazilian Cohort

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC), a rare inherited disease, causes ventricular tachycardia, sudden cardiac death, and heart failure (HF). We investigated ARVC clinical features, genetic findings, natural history, and the occurrence of life-threatening arrhythmic events (LTAEs), HF death, or heart transplantation (HF-death/HTx) to identify risk factors.

METHODS

The clinical course of 111 consecutive patients with definite ARVC, predictors of LTAE, HF-death/HTx, and combined events were analyzed in the entire cohort and in a subgroup of 40 patients without sustained ventricular arrhythmia before diagnosis.

RESULTS

The 5-year cumulative probability of LTAE was 30% and HF-death/HTx was 10%. Predictors of HF-death/HTx were reduced right ventricle ejection fraction (HR: 0.93; P=0.010), HF symptoms (HR: 4.37; P=0.010), epsilon wave (HR: 4.99; P=0.015), and number of leads with low QRS voltage (HR: 1.28; P=0.001). Each additional lead with low QRS voltage increased the risk of HF-death/HTx by 28%. Predictors of LTAE were prior syncope (HR: 1.81; P=0.040), number of leads with T wave inversion (HR: 1.17; P=0.039), low QRS voltage (HR: 1.12; P=0.021), younger age (HR: 0.97; P=0.006), and prior ventricular arrhythmia/ventricular fibrillation (HR: 2.45; P=0.012). Each additional lead with low QRS voltage increased the risk of LTAE by 17%. In patients without ventricular arrhythmia before clinical diagnosis of ARVC, the number of leads with low QRS voltage (HR: 1.68; P=0.023) was independently associated with HF-death/HTx.

CONCLUSIONS

Our study demonstrated the characteristics of a specific cohort with a high prevalence of arrhythmic burden at presentation, male predominance, younger age and HF severe outcomes. Our main results suggest that the presence and extension of low QRS voltage can be a risk predictor for HF-death/HTx in ARVC patients, regardless of the arrhythmic risk. This study can contribute to the global ARVC risk stratification, adding new insights to the international current scientific knowledge.

Radial and Circumferential CMR-Based RV Strain Predicts Low R Wave Amplitude after ICD Implantation in Patients with Arrhythmogenic Cardiomyopathy

Inadequate R wave amplitude (RWA) after implantable cardiac defibrillator (ICD) implantation in patients with arrhythmogenic cardiomyopathy (ACM) was suspected to relate to right ventricle impairment. However, little data-based evidence was provided to quantify the association. We retrospectively enrolled ACM patients receiving CMR examinations before transvenous ICD implantation from Fuwai Hospital. The RWA was obtained within 24 h and at 2-6-month follow-up after the operation. Structural, functional, as well as tissue characterization of the left ventricle (LV) and right ventricle (RV), were analyzed in relation to RWA. Among the 87 ACM patients (median RWA: 8.0 mV), 19 (21.8%) patients were found with low initial RWA (<5 mV) despite attempts in multiple positions. RV end diastolic diameter (RVEDD), (r = -0.44), RV ejection fraction (RVEF, r = 0.43), RV end diastolic volume index (RVEDVi, r = -0.49), RV end systolic volume index (RVESVi, r = -0.53), RV global circumferential (RVGCS, r = -0.64), and radial strain (RVGRS, r = 0.61, all p < 0.001) rather than LV metrics correlated strongly with initial RWA. RVGCS, RVESVi, and RVGRS were decent predictors of low RWA (areas under the curve AUC: 0.814, 0.769, 0.757, respectively) early after implantation and during 2-6-month follow-up. To summarize, low RWA of ICD lead in ACM patients was associated with RV abnormalities. The RVGCS, RVGRS, and RVESVi can be valuable predictors for identifying low RWA prior to ICD implantation.

A Case Report of a Young Patient Presenting With Syncope Secondary to Arrhythmogenic Ventricular Cardiomyopathy

Arrhythmogenic ventricular cardiomyopathy is an inherited condition mainly affecting adults. A 35-year-old Asian male patient presented with syncope while walking home. He experienced a number of episodes of light-headedness and dizziness over the past few weeks. A clinical examination found visible injuries to his face and hands. An electrocardiogram showed right axis deviation and right bundle branch block. Echocardiography showed normal biventricular function and the left ventricular ejection fraction was > 55%. A computerized tomography scan of the head and face showed a small fracture to the superior maxillary wall and a computerized tomography pulmonary angiogram demonstrated an inflammatory nodule with right upper and middle lobes changes as well as right hilar lymphadenopathy, suggestive of possible tuberculosis. Blood tests were unremarkable, and troponin was negative. Cardiovascular magnetic resonance imaging showed preserved biventricular function, mild bi-atrial dilatation, and extensive, crescentic-shaped, subepicardial late gadolinium enhancement from basal to apical inferior, basal to apical lateral, and mid to apical anterior segments of the left ventricle suggestive of arrhythmogenic ventricular cardiomyopathy. The patient was commenced on bisoprolol and had an implantable cardioverter defibrillator fitted. He was discharged home with outpatient cardiology follow-up.

Clinical course of arrhythmogenic right ventricular cardiomyopathy with end-stage heart failure and outcome after heart transplantation

BACKGROUND

Few data exist on the characteristics and outcomes of patients with arrhythmogenic right ventricular cardiomyopathy and advanced heart failure who undergo heart transplantation.

AIM

To explore the pretransplant course and outcomes of patients with arrhythmogenic right ventricular cardiomyopathy after heart transplantation.

METHODS

This observational retrospective monocentric study included all consecutive patients with arrhythmogenic right ventricular cardiomyopathy who underwent heart transplantation during a 13-year period (2006-2019) at Pitié-Salpêtrière University Hospital (Paris).

RESULTS

A total of 23 patients with arrhythmogenic right ventricular cardiomyopathy underwent heart transplantation between 2006 and 2019. The median time from diagnosis to heart transplantation was 9 years, and the median age at transplantation was 50 years. At diagnosis, half of the patients had left ventricular dysfunction, 59% had extensive T-wave inversion and 43% had a history of sustained ventricular tachycardia. Only five patients were involved in intensive sport activity. Indications for heart transplantation were end-stage biventricular dysfunction in 13 patients, end-stage right ventricular heart failure in seven and electrical storm in three. Only three patients had pulmonary hypertension, and half of the patients had atrial arrhythmias. The survival rate 1 year after heart transplantation was 74% (95% confidence interval 53-88%). Eight patients experienced primary graft dysfunction needing extracorporeal membrane oxygenation.

CONCLUSIONS

Patients with arrhythmogenic right ventricular cardiomyopathy who eventually needed heart transplantation mostly exhibited extended disease with biventricular dysfunction at diagnosis. Intensive sport activity did not seem to be a major determinant. Advanced heart failure usually occurred late in the course of the disease. Primary graft dysfunction after heart transplantation was frequent, and should be anticipated. Additional data are needed to identify the optimal timing for heart transplantation and predictors of end-stage heart failure in patients with arrhythmogenic right ventricular cardiomyopathy.

Varied Presentation of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C): A Case Series

Arrhythmogenic right ventricular dysplasia (ARVD) is a genetically predisposed form of cardiomyopathy that mainly affects young individuals resulting in fatal ventricular arrhythmias leading to sudden cardiac death. ARVD has 50% of cases that involve both the right ventricle (RV) and left ventricle (LV), but only a small number of cases involve an isolated left ventricle. In this case series, five patients (four males and one female) with a diagnosis of ARVD presented to our center with varied clinical presentations across a wide range of age groups. The MRI of all five cases showed dilated right atrium (RA)/RV with right ventricular free wall dyskinesia. Two-dimensional (2D) MRI showed aneurysmal outpouching with diffuse free wall enhancement. Automated implantable cardioverter defibrillator (AICD) was implanted uneventfully in all five patients, and the patients were discharged with oral medications such as low-dose diuretics, beta-blockers, spironolactone, angiotensin-converting enzymes (ACE) inhibitors, amiodarone, and anxiolytics. Until now, the patients were doing well on follow-up visits. The therapeutic management of patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) has evolved over the years and continues to be an important challenge. To further improve risk stratification and treatment of patients, more information is needed on natural history, long-term prognosis, and risk assessment. Special attention should be focused on the identification of patients who would benefit from implantable cardioverter-defibrillator (ICD) implantation in comparison to pharmacological and other nonpharmacological approaches.

From background to solutions: Eliminating sex gaps in clinical electrophysiology practice

Sex, a biological construct, and gender, a sociocultural construct, both influence the epidemiology and outcomes of various cardiac arrhythmias, leading to disparities that have been observed in clinical practice. Addressing disparities is crucial to improve the quality of clinical care. We recognize gender equality as the ultimate goal to ensuring equitable health care and propose the following strategies to achieve the goal: sex- and gender-stratified research, quality improvement initiatives, implicit bias training, promotion of women into leadership positions in cardiology, peer support, and shared decision-making to help mitigate disparities. However, further research on how to improve the widespread adoption and implementation of such strategies in the clinical setting is required.

Impact of Amiodarone Therapy on the Ablation Outcome of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy

(1) Background: Catheter ablation (CA) is an accepted treatment option for drug-refractory ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study investigates the effect of amiodarone on ablation outcomes in ARVC. (2) Methods: The study enrolled patients with ARVC undergoing CA of sustained VT. In all patients, substrate modification was performed to achieve non-inducible VT. The patients were categorized into two groups according to whether they had used amiodarone before CA. Baseline and electrophysiological characteristics, substrate, and outcomes were compared. (3) Results: A total of 72 ARVC patients were studied, including 29 (40.3%) "off" amiodarone and 43 (56.7%) "on" amiodarone. The scar area was similar between the two groups. Patients "off" amiodarone had smaller endocardial and epicardial areas with abnormal electrograms. Twenty of 43 patients (47.5%) "on" amiodarone discontinued it within 3 months after CA. During a mean follow-up period of 43.2 ± 29.5 months, higher VT recurrence was observed in patients "on" amiodarone. Patients "on" amiodarone who discontinued amiodarone after CA had a lower recurrence than those without. (4) Conclusions: Patients with ARVC "on" amiodarone before CA had distinct substrate characteristics and worse ablation outcomes than patients "off" amiodarone, especially in those who had used amiodarone continuously.

Using marginal structural joint models to estimate the effect of a time-varying treatment on recurrent events and survival: An application on arrhythmogenic cardiomyopathy

In many clinical applications to evaluate the effect of a treatment, randomized control trials are difficult to carry out. On the other hand, clinical observational registries are often available and they contain longitudinal data regarding clinical parameters, drug therapies, and outcomes. In the past, much research has addressed causal methods to estimate treatment effects from observational studies. In the context of time-varying treatments, marginal structural models are often used. However, most analyses have focused on binary outcomes or time-to-the-first event analyses. The novelty of our approach is to combine the marginal structural methodology with the case where correlated recurrent events and survival are the outcomes of interest. Our work focuses on solving the nontrivial problem of defining the measures of effect, specifying the model for the time-dependent weights and the model to estimate the outcome, implementing them, and finally estimating the final treatment effects in this life-history setting. Our approach provides a strategy that allows obtaining treatment effect estimates both on the recurrent events and the survival with a clear causal and clinical interpretation. At the same time, the strategy we propose is based on flexible modeling choices such as the use of joint models to capture the correlation within events from the same subject and the specification of time-dependent treatment effects. The clinical problem which motivated our work is the evaluation of the treatment effect of beta-blockers in arrhythmogenic right ventricular cardiomyopathy (ARVC/D), and the dataset comes from the Trieste Heart Muscle Disease Registry.

Catheter Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy is an inherited desmosomal myopathy characterized by progressive fibrofatty replacement of the myocardium, right ventricular enlargement, and malignant ventricular arrhythmias. Ventricular tachycardias is one of the most common initial presentation of ARVC. This manuscript addresses invasive VT ablation options for the managmenet of VT in patients with ARVC.

Selection of patients eligible for implantable cardioverter defibrillator: beyond left ventricular ejection fraction

The selection of patients eligible for implantable cardioverter defibrillator (ICD), in primary prevention, is a critical moment in the management of the patients with cardiomyopathies as it needs a right balance of the patients’ arrhythmic risk and the risks related to the implantation, as well as the device costs. Several data indicate that left ventricular ejection fraction alone is not a sufficient criterion for a proper identification of patients who could benefit most from ICD. Numerous findings show that genetic analysis and characterization of myocardial fibrosis with magnetic resonance imaging allow an important improvement of this process.

Arrhythmic risk prediction in arrhythmogenic right ventricular cardiomyopathy: external validation of the arrhythmogenic right ventricular cardiomyopathy risk calculator

AIMS

Arrhythmogenic right ventricular cardiomyopathy (ARVC) causes ventricular arrhythmias (VAs) and sudden cardiac death (SCD). In 2019, a risk prediction model that estimates the 5-year risk of incident VAs in ARVC was developed (ARVCrisk.com). This study aimed to externally validate this prediction model in a large international multicentre cohort and to compare its performance with the risk factor approach recommended for implantable cardioverter-defibrillator (ICD) use by published guidelines and expert consensus.

METHODS AND RESULTS

In a retrospective cohort of 429 individuals from 29 centres in North America and Europe, 103 (24%) experienced sustained VA during a median follow-up of 5.02 (2.05-7.90) years following diagnosis of ARVC. External validation yielded good discrimination [C-index of 0.70 (95% confidence interval-CI 0.65-0.75)] and calibration slope of 1.01 (95% CI 0.99-1.03). Compared with the three published consensus-based decision algorithms for ICD use in ARVC (Heart Rhythm Society consensus on arrhythmogenic cardiomyopathy, International Task Force consensus statement on the treatment of ARVC, and American Heart Association guidelines for VA and SCD), the risk calculator performed better with a superior net clinical benefit below risk threshold of 35%.

CONCLUSION

Using a large independent cohort of patients, this study shows that the ARVC risk model provides good prognostic information and outperforms other published decision algorithms for ICD use. These findings support the use of the model to facilitate shared decision making regarding ICD implantation in the primary prevention of SCD in ARVC.

Implantable defibrillators in primary prevention of genetic arrhythmias. A shocking choice?

Many previously unexplained life-threatening ventricular arrhythmias and sudden cardiac deaths (SCDs) in young individuals are now recognized to be genetic in nature and are ascribed to a growing number of distinct inherited arrhythmogenic diseases. These include hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia (VT), and short QT syndrome. Because of their lower frequency compared to coronary disease, risk factors for SCD are not very precise in patients with inherited arrhythmogenic diseases. As randomized studies are generally non-feasible and may even be ethically unjustifiable, especially in the presence of effective therapies, the risk assessment of malignant arrhythmic events such as SCD, cardiac arrest due to ventricular fibrillation (VF), appropriate implantable cardioverter defibrillator (ICD) interventions, or ICD therapy on fast VT/VF to guide ICD implantation is based on observational data and expert consensus. In this document, we review risk factors for SCD and indications for ICD implantation and additional therapies. What emerges is that, allowing for some important differences between cardiomyopathies and channelopathies, there is a growing and disquieting trend to create, and then use, semi-automated systems (risk scores, risk calculators, and, to some extent, even guidelines) which then dictate therapeutic choices. Their common denominator is a tendency to favour ICD implantation, sometime with reason, sometime without it. This contrasts with the time-honoured approach of selecting, among the available therapies, the best option (ICDs included) based on the clinical judgement for the specific patient and after having assessed the protection provided by optimal medical treatment.