Contemporary diagnostic approach to arrhythmogenic cardiomyopathy: The three-step work-up

Arrhythmogenic Cardiomyopathy (ACM) is a cardiac disorder characterized by non-ischemic myocardial scarring, which may lead to ventricular electrical instability and systolic dysfunction. Diagnosing ACM is challenging as there is no single gold-standard test and a combination of criteria is required. The first diagnostic criteria were established in 1994 and revised in 2010, focusing primarily on right ventricular involvement. However, in 2019, an international expert report identified limitations of previous diagnostic scoring and developed the 2020 Padua criteria with also included criteria for diagnosis of left ventricular variants and introduced cardiac magnetic resonance tissue characterization findings for detection of left ventricular myocardial scar. These criteria were further refined and published in 2023 as the European Task Force criteria, gaining international recognition. This review provides an overview of the 20 years of progresses on the disease diagnostic from the original 1994 criteria to the most recent 2023 European criteria, highlighting the evolution into our understanding of the pathobiology and morpho-functional features of the disease.

The 2023 European Task Force Criteria for Diagnosis of Arrhythmogenic Cardiomyopathy: Historical Background and Review of Main Changes

Arrhythmogenic cardiomyopathy (ACM) is a cardiac disease featured by non-ischemic myocardial scarring linked to ventricular electrical instability. As there is no single gold-standard test, diagnosing ACM remains challenging and a combination of specific criteria is needed. The diagnostic criteria were first defined and widespread in 1994 and then revised in 2010, approaching and focusing primarily on right ventricular involvement without considering any kind of left ventricular variant or phenotype. Years later, in 2020, with the purpose of overcoming previous limitations, the Padua Criteria were introduced by an international expert report. The main novel elements were the introduction of specific criteria for left ventricular variants as well as the use of cardiac magnetic resonance for tissue characterization and scar detection. The last modifications and refinement of these criteria were published at the end of 2023 as the European Task Force criteria, by a "head-quarter" of ACM international experts, proving the emerging relevance of this condition besides its difficult diagnosis. In this review, emphasizing the progress in understanding the aetiology of the cardiomyopathy, an analysis of the new criteria is presented. The introduction of the term "scarring/arrhythmogenic cardiomyopathy" sets an important milestone in this field, underlying how non-ischemic myocardial scarring-typical of ACM-and arrhythmic susceptibility could be the main pillars of numerous different phenotypic variants regardless of etiology.

Arrhythmogenic Left Ventricular Cardiomyopathy: From Diagnosis to Risk Management

PURPOSE OF REVIEW

Left ventricular arrhythmogenic cardiomyopathy (ALVC) is a rare and poorly characterized cardiomyopathy that has recently been reclassified in the group of non-dilated left ventricular cardiomyopathies. This review aims to summarize the background, diagnosis, and sudden cardiac death risk in patients presenting this cardiomyopathy.

RECENT FINDINGS

Although there is currently a lack of data on this condition, arrhythmogenic left ventricular dysplasia can be considered a specific disease of the left ventricle (LV). We have collected the latest evidence about the management and the risks associated with this cardiomyopathy.

SUMMARY

Left ventricular arrhythmogenic cardiomyopathy is still poorly characterized. ALVC is characterized by fibrofatty replacement in the left ventricular myocardium, with variable phenotypic expression. Diagnosis is based on a multiparametric approach, including cardiac magnetic resonance (CMR) and genetic testing, and is important for sudden cardiac death (SCD) risk stratification and management. Recent guidelines have improved the management of left ventricular arrhythmogenic cardiomyopathy. Further studies are necessary to improve knowledge of this cardiomyopathy.

Proposed diagnostic criteria for arrhythmogenic cardiomyopathy: European Task Force consensus report

Arrhythmogenic cardiomyopathy (ACM) is a heart muscle disease characterized by prominent "non-ischemic" myocardial scarring predisposing to ventricular electrical instability. Diagnostic criteria for the original phenotype, arrhythmogenic right ventricular cardiomyopathy (ARVC), were first proposed in 1994 and revised in 2010 by an international Task Force (TF). A 2019 International Expert report appraised these previous criteria, finding good accuracy for diagnosis of ARVC but a lack of sensitivity for identification of the expanding phenotypic disease spectrum, which includes left-sided variants, i.e., biventricular (ABVC) and arrhythmogenic left ventricular cardiomyopathy (ALVC). The ARVC phenotype together with these left-sided variants are now more appropriately named ACM. The lack of diagnostic criteria for the left ventricular (LV) phenotype has resulted in clinical under-recognition of ACM patients over the 4 decades since the disease discovery. In 2020, the "Padua criteria" were proposed for both right- and left-sided ACM phenotypes. The presently proposed criteria represent a refinement of the 2020 Padua criteria and have been developed by an expert European TF to improve the diagnosis of ACM with upgraded and internationally recognized criteria. The growing recognition of the diagnostic role of CMR has led to the incorporation of myocardial tissue characterization findings for detection of myocardial scar using the late‑gadolinium enhancement (LGE) technique to more fully characterize right, biventricular and left disease variants, whether genetic or acquired (phenocopies), and to exclude other "non-scarring" myocardial disease. The "ring-like' pattern of myocardial LGE/scar is now a recognized diagnostic hallmark of ALVC. Additional diagnostic criteria regarding LV depolarization and repolarization ECG abnormalities and ventricular arrhythmias of LV origin are also provided. These proposed upgrading of diagnostic criteria represents a working framework to improve management of ACM patients.

Electroanatomic mapping in athletes: Why and when. An expert opinion paper from the Italian Society of Sports Cardiology

Three-dimensional electroanatomical mapping (EAM) has the potential to identify the pathological substrate underlying ventricular arrhythmias (VAs) in different clinical settings by detecting myocardial areas with abnormally low voltages, which reflect the presence of different cardiomyopathic substrates. In athletes, the added value of EAM may be to enhance the efficacy of third-level diagnostic tests and cardiac magnetic resonance (CMR) in detecting concealed arrhythmogenic cardiomyopathies. Additional benefits of EAM in the athlete include the potential impact on disease risk stratification and the consequent implications for eligibility to competitive sports. This opinion paper of the Italian Society of Sports Cardiology aims to guide general sports medicine physicians and cardiologists on the clinical decision when to eventually perform an EAM study in the athlete, highlighting strengths and weaknesses for each cardiovascular disease at risk of sudden cardiac death during sport. The importance of early (preclinical) diagnosis to prevent the negative effects of exercise on phenotypic expression, disease progression, and worsening of the arrhythmogenic substrate is also addressed.

Clinical and Electrophysiological Characteristics of Ventricular Tachycardias From the Basal Septum in Structural Heart Disease

OBJECTIVES

This study describes the clinical and electrophysiological characteristics of basal-septal ventricular tachycardias (VTs) in patients with structural heart disease (SHD).

BACKGROUND

The basal septum is a common source of VT in patients with SHD.

METHODS

Data from 312 consecutive patients with SHD undergoing catheter ablation of ventricular arrhythmias were reviewed.

RESULTS

Thirty-three basal-septal VTs in 31 patients (mean age 67.4 ± 14.2 years, mean left ventricular ejection fraction [LVEF] 42% ± 15%) were identified. Patients with VTs with left ventricular basal-septal breakthrough were more likely to have ischemic cardiomyopathy and lower LVEF; patients with right ventricular basal-septal VT were more likely to have sarcoidosis or right ventricular cardiomyopathy of unknown significance, with higher LVEF. Atrioventricular block was present in 45% of patients and intraventricular block including persistent biventricular pacing in 77%. Unipolar scar was larger than bipolar scar (area 18.8% ± 19.4% vs 12.7% ± 14.6%; P < 0.001). VTs with right bundle branch block configuration and S wave in lead V₆ with positive V₃/V₄ polarity consistently indicated left ventricular basal-septal breakthrough. Inferior limb-lead discordance with right bundle branch block configuration and "reverse pattern break in lead V₂" were identified in left ventricular basal inferior-septal origin in 3 patients. VT noninducibility was achieved in 55%, and VT recurred in 42% of patients after a single procedure, but VT burden was significantly reduced after ablation (59 episodes before vs 2 episodes after ablation; P = 0.02).

CONCLUSIONS

Basal-septal VTs in patients with SHD have a distinct clinical, electrocardiographic, and electrophysiological profile depending on the breakthrough site, accompanied by a deep intramural septal substrate that limits procedural success after catheter ablation.

The precordial R' wave: A novel discriminator between cardiac sarcoidosis and arrhythmogenic right ventricular cardiomyopathy in patients presenting with ventricular tachycardia

BACKGROUND

Cardiac sarcoidosis (CS) with right ventricular (RV) involvement can mimic arrhythmogenic right ventricular cardiomyopathy (ARVC). Histopathological differences may result in disease-specific RV activation patterns detectable on the 12-lead electrocardiogram. Dominant subepicardial scar in ARVC leads to delayed activation of areas with reduced voltages, translating into terminal activation delay and occasionally (epsilon) waves with a small amplitude. Conversely, patchy transmural RV scar in CS may lead to conduction block and therefore late activated areas with preserved voltages reflected as preserved R' waves.

OBJECTIVE

The purpose of this study was to evaluate the distinct terminal activation patterns in precordial leads V₁ through V₃ as a discriminator between CS and ARVC.

METHODS

Thirteen patients with CS affecting the RV and 23 patients with gene-positive ARVC referred for ventricular tachycardia ablation were retrospectively included in a multicenter approach. A non-ventricular-paced 12-lead surface electrocardiogram was analyzed for the presence and the surface area of the R' wave (any positive deflection from baseline after an S wave) in leads V₁ through V₃.

RESULTS

An R' wave in leads V₁ through V₃ was present in all patients with CS compared to 11 (48%) patients with ARVC (P = .002). An algorithm including a PR interval of ≥220 ms, the presence of an R' wave, and the surface area of the maximum R' wave in leads V₁ through V₃ of ≥1.65 mm² had 85% sensitivity and 96% specificity for diagnosing CS, validated in a second cohort (18 CS and 40 ARVC) with 83% sensitivity and 88% specificity.

CONCLUSION

An easily applicable algorithm including PR prolongation and the surface area of the maximum R' wave in leads V₁ through V₃ of ≥1.65 mm² distinguishes CS from ARVC. This QRS terminal activation in precordial leads V₁ through V₃ may reflect disease-specific scar patterns.

Management of Cardiac Sarcoidosis in 2020

Sarcoidosis is an inflammatory granulomatous disease that can affect any organ. Up to one-quarter of patients with systemic sarcoidosis may have evidence of cardiac involvement. The clinical manifestations of cardiac sarcoidosis (CS) include heart block, atrial arrhythmias, ventricular arrhythmias and heart failure. The diagnosis of CS can be challenging given the patchy infiltration of the myocardium but, with the increased availability of advanced cardiac imaging, more cases of CS are being identified. Immunosuppression with corticosteroids remains the standard therapy for the acute inflammatory phase of CS, but there is an evolving role of steroid-sparing agents. In this article, the authors provide an update on the diagnosis of CS, including the role of imaging; review the clinical manifestations of CS, namely heart block, atrial and ventricular arrhythmias and heart failure; discuss updated management strategies, including immunosuppression, electrophysiological and heart failure therapies; and identify the current gaps in knowledge and future directions for cardiac sarcoidosis.

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

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

Substrate Mapping and Ablation for Ventricular Tachycardia in Patients with Structural Heart Disease: How to Identify Ventricular Tachycardia Substrate

Catheter ablation for ventricular tachycardia (VT) has been increasingly used over the past two decades in patients with structural heart disease (SHD). In these individuals, a substrate mapping strategy is being more commonly applied to identify targets for VT ablation, which has been shown to be more effective versus targeting mappable VTs alone. There are a number of substrate mapping methods in existence that aim to explore potential VT isthmuses, although their success rates vary. Most of the reported electrogram-based mapping studies have been performed with ablation catheters; meanwhile, the use of multipolar mapping catheters with smaller electrodes and closer interelectrode spacing has emerged, which allows for an assessment of detailed near-field abnormal electrograms at a higher resolution. Another recent advancement has occurred in the use of imaging techniques in VT ablation, particularly in refining the substrate. The goal of this paper is to review the key developments and limitations of current mapping strategies of substrate-based VT ablation and their outcomes. In addition, we briefly summarize the role of cardiac imaging in delineating VT substrate.

Management of Arrhythmias Associated with Cardiac Sarcoidosis

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology. The annual incidence of systemic sarcoidosis is estimated at 10-20 per 100,000 individuals. Owing to the recent advances in imaging modalities, cardiac sarcoidosis (CS) is diagnosed more frequently. The triad of CS includes conduction abnormality, ventricular tachycardia, and heart failure. Atrial and ventricular arrhythmias are caused by either inflammation or scar formation. Inflammation should be treated with immunosuppression and antiarrhythmic agents and scar formation should be treated with antiarrhythmics and/or ablation, in addition to implantable cardioverter defibrillator (ICD) implantation, if necessary. Ablation can provide a good outcome, but it might require bipolar ablation if the critical portion is located mid-myocardium. Late recurrence might be caused by reactivation of sarcoidosis, which would need to be evaluated by positron emission tomography-computed tomography imaging. Risk of sudden cardiac death (SCD) in patients with advanced atrioventricular block is not low, and ICD implantation could be considered instead of a pacemaker. For risk stratification for SCD, late gadolinium enhancement by cardiac magnetic resonance imaging or program stimulation is often used.

Ventricular Arrhythmias in Cardiac Sarcoidosis

The diagnosis of cardiac sarcoidosis (CS), especially in cases where there is limited or no extracardiac involvement, is challenging. Patients with CS are at increased risk of ventricular arrhythmias and sudden cardiac death. Several techniques for risk stratification for sudden cardiac death have been proposed in this population, including advanced cardiac imaging and electrophysiology study. Clinical ventricular arrhythmias in patients with CS may be treated with immunosuppressant therapy, antiarrhythmic drugs, catheter ablation, or implantable cardioverter-defibrillator placement. This article will provide an update on techniques for diagnosing CS, risk stratifying patients with CS for sudden cardiac death, and treating patients with CS with ventricular arrhythmias, focusing on evidence that has become available since publication of the 2014 Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Management of Arrhythmias Associated With Cardiac Sarcoidosis.