Mutation-positive arrhythmogenic right ventricular dysplasia/cardiomyopathy: the triangle of dysplasia displaced

Left ventricular fibro-fatty replacement in arrhythmogenic right ventricular dysplasia/cardiomyopathy: prevalence, patterns, and association with arrhythmias

BACKGROUND

Left ventricular (LV) fibrofatty infiltration in arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy (ARVD/C) has been reported, however, detailed cardiovascular magnetic resonance (CMR) characteristics and association with outcomes are uncertain. We aim to describe LV findings on CMR in ARVD/C patients and their relationship with arrhythmic outcomes.

METHODS

CMR of 73 subjects with ARVD/C according to the 2010 Task Force Criteria (TFC) were analyzed for LV involvement, defined as ≥ 1 of the following features: LV wall motion abnormality, LV late gadolinium enhancement (LGE), LV fat infiltration, or LV ejection fraction (LVEF) < 50%. Ventricular volumes and function, regional wall motion abnormalities, and the presence of ventricular fat or fibrosis were recorded. Findings on CMR were correlated with arrhythmic outcomes.

RESULTS

Of the 73 subjects, 50.7% had CMR evidence for LV involvement. Proband status and advanced RV dysfunction were independently associated with LV abnormalities. The most common pattern of LV involvement was focal fatty infiltration in the sub-epicardium of the apicolateral LV with a "bite-like" pattern. LGE in the LV was found in the same distribution and most often had a linear appearance. LV involvement was more common with non-PKP2 genetic mutation variants, regardless of proband status. Only RV structural disease on CMR (HR 3.47, 95% CI 1.13-10.70) and prior arrhythmia (HR 2.85, 95% CI 1.33-6.10) were independently associated with arrhythmic events.

CONCLUSION

Among patients with 2010 TFC for ARVD/C, CMR evidence for LV abnormalities are seen in half of patients and typically manifest as fibrofatty infiltration in the subepicardium of the apicolateral wall and are not associated with arrhythmic outcomes.

Arrhythmogenic right ventricular cardiomyopathy: a focused update on diagnosis and risk stratification

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterised by fibrofatty replacement of predominantly the right ventricle and high risk of ventricular arrhythmias and sudden cardiac death (SCD). Early diagnosis and accurate risk assessment are challenging yet essential for SCD prevention. This manuscript summarises the current state of the art on ARVC diagnosis and risk stratification. Improving the 2010 diagnostic criteria is an ongoing discussion. Several studies suggest that early diagnosis may be facilitated by including deformation imaging ('strain') for objective assessment of wall motion abnormalities, which was shown to have high sensitivity for preclinical disease. Adding fibrofatty replacement detected by late gadolinium enhancement or T1 mapping in cardiac MRI as criterion for diagnosis is increasingly suggested but requires more supporting evidence from consecutive patient cohorts. In addition to the traditional right-dominant ARVC, standard criteria for arrhythmogenic cardiomyopathy (ACM) and arrhythmogenic left ventricular cardiomyopathy (ALVC) are on the horizon. After diagnosis confirmation, the primary management goal is SCD prevention, for which an implantable cardioverter-defibrillator is the only proven therapy. Prior studies determined that younger age, male sex, previous (non-) sustained ventricular tachycardia, syncope, extent of T-wave inversion, frequent premature ectopic beats and lower biventricular ejection fraction are risk factors for subsequent events. Previous implantable cardioverter-defibrillator indication guidelines were however limited to three expert-opinion flow charts stratifying patients in risk groups. Now, two multivariable risk prediction models (arvcrisk.com) combine the abovementioned risk factors to estimate individual risks. Of note, both the flow charts and prediction models require clinical validation studies to determine which should be recommended.

A 3D high resolution MRI method for the visualization of cardiac fibro-fatty infiltrations

Modifications of the myocardial architecture can cause abnormal electrical activity of the heart. Fibro-fatty infiltrations have been implicated in various cardiac pathologies associated with arrhythmias and sudden cardiac death, such as arrhythmogenic right ventricular cardiomyopathy (ARVC). Here, we report the development of an MRI protocol to observe these modifications at 9.4 T. Two fixed ex vivo human hearts, one healthy and one ARVC, were imaged with an Iterative decomposition with echo asymmetry and least-square estimations (IDEAL) and a magnetization transfer (MT) 3D sequences. The resulting fat fraction and MT ratio (MTR) were analyzed and compared to histological analysis of the three regions (“ARVC triangle”) primarily involved in ARVC structural remodeling. In the ARVC heart, high fat content was observed in the “ARVC triangle” and the superimposition of the MTR and fat fraction allowed the identification of fibrotic regions in areas without the presence of fat. The healthy heart exhibited twice less fat than the ARVC heart (31.9%, 28.7% and 1.3% of fat in the same regions, respectively). Localization of fat and fibrosis were confirmed by means of histology. This non-destructive approach allows the investigation of structural remodeling in human pathologies where fibrosis and/or fatty tissue infiltrations are expected to occur.

Right ventricular dysplasia in the elderly: a case report from autopsy

Right ventricular dysplasia (RVD) is a rare disease of the heart that primarily affects the right ventricle. It is a clinical and pathological entity that presents classically with palpitations, syncope, or even sudden death. It presents rarely in the elderly. Where sudden death is the first and only presentation, an autopsy is required to make the diagnosis. However, the pathomorphological features of RVD can easily be overlooked or missed at autopsy. We report the case of a 68-year-old male with the past medical history of hypertension, gout and inflammatory bowel syndrome. He was admitted on account of difficulty in breathing, abdominal swelling and reduced urination. Physical examination revealed hypertension with cardiac murmurs, widespread crepitations, distended abdomen and lower limb oedema. Provisional diagnoses of acute-on-chronic kidney disease and congestive cardiac failure secondary to hypertensive heart disease, precipitated by probable gastrointestinal infection were made. While on admission, he had an episode of syncope. Electrocardiogram revealed bigeminy and bradycardic sinus rhythm with unifocal ventricular premature contraction. He died on the 8^th week of admission. Autopsy revealed an enlarged heart weighing 600gm; there was thinning of the apical aspect of the right ventricular wall with subtotal fibrofatty replacement. Microscopic examination revealed a transmural replacement of cardiac myocytes by fibroadipose tissue extending inwards, in the most parts, from the epicardium to the endocardial surface. Our aim is to increase the awareness of these pathomorphological features among anatomic/forensic pathologists.

Left ventricular involvement assessed by LGE-CMR in predicting the risk of adverse outcomes of arrhythmogenic cardiomyopathy with ICDs

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is characterized by a high incidence of ventricular tachyarrhythmia and sudden death. Implantable cardioverter-defibrillator (ICD) implantation is the cornerstone of management.

OBJECTIVE

This study aims to reveal the prognostic value of the contrast-enhanced cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) amount in predicting varying lethal outcomes among ACM patients with ICDs.

METHODS

The 88 patients with definite ACM who were all referred for contrast-enhanced CMR received an ICD and were followed up for a median of 4.0 years.

RESULTS

Fifty-four patients had no left ventricular (LV) involvement and sixteen had an LV LGE amount > 15%. During the follow-up time, appropriate ICD therapy was seen in 57, electrical storm (ES) in 19, and cardiac death in 9 patients. Compared with those without LV involvement, patients with LV LGE amount > 15% had a higher risk of cardiac death (log-rank P = 0.021). LV LGE amount was associated with an increased risk of ICD therapy [adjusted hazard ratio (HR) 1.035, 95% confidence interval (CI) 1.008-1.062, P = 0.010], and cardiac death (adjusted HR 1.082, 95% 1.006-1.164, P = 0.034), independently of LV ejection fraction. LV LGE mass of >15% demonstrated an over 2-fold increase in ICD therapy (adjusted HR 2.180, 95%CI 1.058-4.488, P = 0.035) and an over 7-fold increase in cardiac death (unadjusted HR 7.198, 95%CI 1.399-37.043, P = 0.018) than those without LV involvement, respectively.

CONCLUSIONS

The LV LGE-CMR in ACM shows a dose-dependent association with ICD therapy and cardiac death. And LV LGE amount of >15% is a strong predictor.

Electromechanical substrate characterization in arrhythmogenic cardiomyopathy using imaging-based patient-specific computer simulations

AIMS

Arrhythmogenic cardiomyopathy (AC) is an inherited cardiac disease, characterized by life-threatening ventricular arrhythmias and progressive cardiac dysfunction. The aim of this study is to use computer simulations to non-invasively estimate the individual patient's myocardial tissue substrates underlying regional right ventricular (RV) deformation abnormalities in a cohort of AC mutation carriers.

METHODS AND RESULTS

In 68 AC mutation carriers and 20 control subjects, regional longitudinal deformation patterns of the RV free wall (RVfw), interventricular septum (IVS), and left ventricular free wall (LVfw) were obtained using speckle-tracking echocardiography. We developed and used a patient-specific parameter estimation protocol based on the multi-scale CircAdapt cardiovascular system model to create virtual AC subjects. Using the individual's deformation data as model input, this protocol automatically estimated regional RVfw and global IVS and LVfw tissue properties. The computational model was able to reproduce clinically measured regional deformation patterns for all subjects, with highly reproducible parameter estimations. Simulations revealed that regional RVfw heterogeneity of both contractile function and compliance were increased in subjects with clinically advanced disease compared to mutation carriers without clinically established disease (17 ± 13% vs. 8 ± 4%, P = 0.01 and 18 ± 11% vs. 10 ± 7%, P < 0.01, respectively). No significant difference in activation delay was found.

CONCLUSION

Regional RV deformation abnormalities in AC mutation carriers were related to reduced regional contractile function and tissue compliance. In clinically advanced disease stages, a characteristic apex-to-base heterogeneity of tissue abnormalities was present in the majority of the subjects, with most pronounced disease in the basal region of the RVfw.

Right Ventricular Functional Abnormalities in Arrhythmogenic Cardiomyopathy: Association With Life-Threatening Ventricular Arrhythmias

OBJECTIVES

This study aimed to perform an external validation of the value of right ventricular (RV) deformation patterns and RV mechanical dispersion in patients with arrhythmogenic cardiomyopathy (AC). Secondly, this study assessed the association of these parameters with life-threatening ventricular arrhythmia (VA).

BACKGROUND

Subtle RV dysfunction assessed by echocardiographic deformation imaging is valuable in AC diagnosis and risk prediction. Two different methods have emerged, the RV deformation pattern recognition and RV mechanical dispersion, but these have neither been externally validated nor compared.

METHODS

We analyzed AC probands and mutation-positive family members, matched from 2 large European referral centers. We performed speckle tracking echocardiography, whereby we classified the subtricuspid deformation patterns from normal to abnormal and assessed RV mechanical dispersion from 6 segments. We defined VA as sustained ventricular tachycardia, appropriate implantable cardioverter-defibrillator therapy, or aborted cardiac arrest.

RESULTS

We included 160 subjects, 80 from each center (43% proband, 55% women, age 41 ± 17 years). VA had occurred in 47 (29%) subjects. In both cohorts, patients with a history of VA showed abnormal deformation patterns (96% and 100%) and had greater RV mechanical dispersion (53 ± 30 ms vs. 30 ± 21 ms; p < 0.001 for the total cohort). Both parameters were independently associated to VA (adjusted odds ratio: 2.71 [95% confidence interval: 1.47 to 5.00] per class step-up, and 1.26 [95% confidence interval: 1.07 to 1.49]/10 ms, respectively). The association with VA significantly improved when adding RV mechanical dispersion to pattern recognition (net reclassification improvement 0.42; p = 0.02 and integrated diagnostic improvement 0.06; p = 0.01).

CONCLUSIONS

We externally validated 2 RV dysfunction parameters in AC. Adding RV mechanical dispersion to RV deformation patterns significantly improved the association with life-threatening VA, indicating incremental value.

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.

[Clinical profile and therapeutic strategies in patients with arrhythmogenic cardiomyopathy treated in a national reference institute]

Objective

To determine the epidemiological, clinical, electrocardiographic, imaging characteristics and main therapeutic strategies performed in patients with arrhythmogenic cardiomyopathy treated in a national reference cardiovascular institute.

Materials and methods

Observational, descriptive and retrospective study that attempts to identify the clinical characteristics, complementary tests and therapeutic strategies performed in patients with arrhythmogenic cardiomyopathy treated at the Instituto Nacional Cardiovascular - INCOR EsSalud in Lima, Peru.

Results

Thirteen patients were found with arrhythmogenic cardiomyopathy. The median age at which the diagnosis was made was 38.2 years and 69.3% were male. The most frequent clinical manifestations were tachycardic palpitations (92.3%), presyncope (84.6%) and heart failure (69.2%). 23% of the patients suffered a cardiac arrest. All the patients presented at least one episode of ventricular tachycardia, 92.3% with complete left bundle branch block morphology and upper axis. 76.9% received an implantable cardioverter defibrillator (ICD), 15.3% underwent ablation and 15.3% received a heart transplant. 84.6% of the patients live to this day.

Conclusions

Arrhythmogenic cardiomyopathy predominantly affected the young and male population. All the patients had a potentially fatal ventricular arrhythmia. Biventricular disease by echocardiography and cardiac magnetic resonance occurred in 69.2% and 100% of the cases, respectively. The therapeutic strategies used were antiarrhythmic medical treatment, placement of an ICD as secondary prevention, ablation, and heart transplantation. To date, 84.6% of patients survive.

Left Ventricular Dysfunction in Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): Can We Separate ARVC From Other Arrhythmogenic Cardiomyopathies?

Arrhythmogenic right ventricular cardiomyopathy was first described as a right ventricular disease that is an important cause of death in young adults. However, with the advent of advanced imaging, arrhythmogenic right ventricular cardiomyopathy has been found to commonly have biventricular involvement, and a small portion of patients have left ventricular–dominant forms. On the other hand, a number of primarily left ventricular disease such as sarcoid and myocarditis can be arrhythmogenic and have right ventricular involvement. A few recent publications on arrhythmogenic right ventricular cardiomyopathy cohorts have average left ventricular functions that are comparable to sarcoid or myocarditis cohorts. We review the current literature and compare these cohorts of patients, and call for left ventricular functional criteria for arrhythmogenic right ventricular cardiomyopathy as inherited arrhythmogenic cardiomyopathy.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Arrhythmogenic Right Ventricular Cardiomyopathy Diagnosis

Arrhythmogenic right ventricular cardiomyopathy, formerly called "arrhythmogenic right ventricular dysplasia," is an under-recognized clinical entity characterized by ventricular arrhythmias and a characteristic ventricular pathology. Diagnosis is often difficult due to the nonspecific nature of the disease and the broad spectrum of phenotypic variations. Therefore, consensus diagnostic criteria have been developed which combine electrocardiographic, echocardiographic, cardiac magnetic resonance imaging and histologic criteria. In 1994, an international task force first proposed the major and minor diagnostic criteria of arrhythmogenic right ventricular cardiomyopathy based on family history, arrhythmias, electrocardiographic abnormalities, tissue characterization, and structural and functional right ventricular abnormalities. In 2010, the task force criteria were revised to include quantitative abnormalities. These diagnostic modalities and the most recent task force criteria are discussed in this review.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

RV Tissue Heterogeneity on CT: A Novel Tool to Identify the VT Substrate in ARVC

OBJECTIVES

This study sought to evaluate whether right ventricular (RV) tissue heterogeneity on computed tomography (CT): 1) is associated with conduction delay in arrhythmogenic right ventricular cardiomyopathy (ARVC); and 2) distinguishes patients with ARVC from those with exercise-induced arrhythmogenic remodeling (EIAR) and control individuals.

BACKGROUND

ARVC is characterized by fibrofatty replacement, related to conduction delay and ventricular tachycardias. Distinguishing ARVC from acquired, EIAR is challenging.

METHODS

Patients with ARVC or EIAR and combined endocardial-epicardial electroanatomic voltage mapping for VT ablation with CT integration were enrolled. Patients without structural heart disease served as control individuals. Tissue heterogeneity on CT (CT heterogeneity) was automatically quantified within the 2-mm subepicardium of the entire RV free wall at normal sites and low voltage sites harboring late potentials (LP+) in ARVC/EIAR.

RESULTS

Seventeen patients with ARVC (15 males; age: 50 ± 17 years), 9 patients with EIAR (7 males; age: 45 ± 14 years) and 17 control individuals (14 males; age: 50 ± 15 years) were enrolled. Of 5,215 ARVC mapping points, 560 (11%) showed LP+. CT heterogeneity was higher at sites with LP+ compared to normal sites (median: 31 HU/mm; IQR: 23 to 46 HU/mm vs. median: 16 HU/mm; IQR: 13 to 21 HU/mm; p < 0.001). The optimal CT heterogeneity cutoff for detection of LP+ was 25 HU/mm (area under the curve [AUC]: 0.80; sensitivity: 72%; specificity: 78%). Overall CT heterogeneity allowed highly accurate differentiation between patients with ARVC and control individuals (AUC: 0.97; sensitivity: 100%; specificity: 82%) and between ARVC and EIAR (AUC: 0.78; sensitivity: 65%; specificity: 89%).

CONCLUSIONS

In patients with ARVC, tissue heterogeneity on CT can be used to identify LP+ as a surrogate for ventricular tachycardia substrate. The overall tissue heterogeneity on CT allows the distinguishing of patients with ARVC from those with EIAR and control individuals.

Comparison of different prediction models for the indication of implanted cardioverter defibrillator in patients with arrhythmogenic right ventricular cardiomyopathy

Aims

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with a high risk of sudden cardiac death. Three different prediction models for the indication of implanted cardioverter defibrillator (ICD) are now available: the 5 year ARVC risk score, the International Task Force Consensus (ITFC) criteria, and the Heart Rhythm Society (HRS) criteria. We compared these three prediction models in a validation cohort of patients with definite ARVC.

Methods and results

In a cohort of 140 patients with definite ARVC, the 5 year ARVC risk score and the ITFC and HRS criteria were compared for the prediction of a major combined endpoint of sudden cardiac death, appropriate ICD intervention, resuscitated cardiac arrest, and sustained ventricular tachycardia. During the follow‐up, 65 major events occurred. The 5 year ARVC risk score with a threshold >10%, derived from the maximally selected rank statistic, predicted 62 (95%) events [odds ratio (OR) 9.1, 95% confidence interval (CI) 2.6–32, P = 0.0006], the ITFC criteria 53 (81%, OR 4.8, 95% CI 2.2–10.3, P = 0.0001), and the HRS criteria 29 (45%, OR 4.2, 95% CI 1.9–9.3, P = 0.0003). At the analysis of decision curve for ICD implantation, a 5 year ARVC risk score >10% showed a greater net benefit than the ITFC and HRS criteria over a wide range of threshold probability of events. Finally, at multivariate analysis, the 5 year ARVC risk score >10% was the only independent predictor of major events.

Conclusions

The 5 year score with a threshold of >10% was more effective for predicting events than the ITFC and HRS criteria.

Epicardial Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease characterized by progressive fibrofatty replacement of the myocardium, right ventricular enlargement, and malignant ventricular arrhythmias. Ventricular tachycardia (VT) may be seen in all stages of the disease and is associated with sudden cardiac death. In patients who failed anti-arrhythmic medical therapy, catheter ablation has become an attractive therapeutic option to reduce VT burden and implantable cardioverter-defibrillator interventions. In this article, the authors aim to address the overall concepts of epicardial catheter ablation in ARVC, focusing on substrate characterization and ablation strategies.

Catheter Ablation of Ventricular Tachycardia in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: A Sequential Approach

Background

It has been suggested that endocardial and epicardial ablation of ventricular tachycardia (VT) improves outcome in arrhythmogenic right ventricular cardiomyopathy/dysplasia. We investigated our sequential approach for VT ablation in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia in a single center.

Methods and Results

We included 47 patients (44±16 years) with definite (81%) or borderline (19%) arrhythmogenic right ventricular cardiomyopathy/dysplasia between 1998 and 2016. Our ablation strategy was to target the endocardial substrate. Epicardial ablation was performed in case of acute ablation failure or lack of an endocardial substrate. Single and multiple procedural 1‐ and 5‐year outcome data for the first occurrence of the study end points (sustained VT/ventricular fibrillation, heart transplant, and death after the index procedure, and sustained VT/ventricular fibrillation for multiple procedures) are reported. Eighty‐one radiofrequency ablation procedures were performed (mean 1.7 per patient, range 1–4). Forty‐five (56%) ablation procedures were performed via an endocardial, 11 (13%) via an epicardial, and 25 (31%) via a combined endo‐ and epicardial approach. Complete acute success was achieved in 65 (80%) procedures, and partial success in 13 (16%). After a median follow‐up of 50.8 (interquartile range, [18.6; 99.2]) months after the index procedure, 17 (36%) patients were free from the primary end point. After multiple procedures, freedom from sustained VT/ventricular fibrillation was 63% (95% CI, 52–75) at 1 year, and 45% (95% CI, 34–61) at 5 years, with 36% of patients receiving only endocardial radiofrequency ablation. A trend (log rank P=0.058) towards an improved outcome using a combined endo‐/epicardial approach was observed after multiple procedures.

Conclusion

Endocardial ablation can be effective in a considerable number of arrhythmogenic right ventricular cardiomyopathy/dysplasia patients with VT, potentially obviating the need for an epicardial approach.

The arrhythmogenic right ventricular cardiomyopathy in comparison to the athletic heart

Intense exercise-induced right ventricular remodeling is a potential adaptation of cardiac function and structure. The features of the remodeling may overlap with those of a very early form of arrhythmogenic right ventricular cardiomyopathy (ARVC): at this early stage, it could be difficult to discriminate ARVC, from exercise-induced cardiac adaptation that may develop in normal individuals. The purpose of this paper is to discuss which exercise-induced remodeling may be a pathological or a physiological finding. A complete evaluation may be required to identify the pathological features of ARVC that would include potential risk of sudden cardiac death during sport or, to avoid the false diagnosis of ARVC. The most recent expert assessment of arrhythmogenic cardiomyopathy focuses on endurance athletes presenting with clinical features indistinguishable from ARVC.

Endo-epicardial ablation vs endocardial ablation for the management of ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy: A systematic review and meta-analysis

BACKGROUND

The pathologic process of ARVC (arrhythmogenic right ventricular cardiomyopathy) typically originates in the epicardium or subepicardial layers with progression toward endocardium. However, in the most recent ARVC international task force consensus statement, epicardial ventricular tachycardia (VT) ablation is recommended as a Class I indication only in patients with at least one failed endocardial VT ablation attempt.

OBJECTIVE

The aim of this meta-analysis is to assess the outcomes of ARVC patients undergoing combined endo-epicardial VT ablation, as compared to endocardial ablation alone.

METHODS

A systematic review of PubMed, Embase, and Cochrane was performed for studies reporting clinical outcomes of endo-epicardial VT ablation vs endocardial-only VT ablation in patients with ARVC. Fixed-Effect model was used if I₂ < 25 and the Random-Effects Model was used if I₂ ≥ 25%.

RESULTS

Nine studies consisting of 452 patients were included (mean age 42.3 ± 5.7 years; 70% male). After a mean follow-up of 48.1 ± 21.5 months, endo-epicardial ablation was associated with 42% relative risk reduction in VA recurrence as opposed to endocardial ablation alone (risk ratio [RR], 0.58; 95% confidence interval [CI], 0.45-0.75; P < .0001). No significant differences were noted between endo-epicardial and endocardial VT ablation groups in terms of all-cause mortality (RR, 1.19; 95% CI, 0.03-47.08; P = .93) and acute procedural complications (RR, 5.39; 95% CI, 0.60-48.74; P = .13).

CONCLUSIONS

Our findings suggest that in patients with ARVC, endo-epicardial VT ablation is associated with a significant reduction in VA recurrence as opposed to endocardial ablation alone, without a significant difference in all-cause mortality or acute procedural complications.

Development of an algorithm for automatic classification of right ventricle deformation patterns in arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Different disease stages of arrhythmogenic right ventricular cardiomyopathy (ARVC) can be identified by right ventricle (RV) longitudinal deformation (strain) patterns. This requires assessment of the onset of shortening, (systolic) peak strain, and postsystolic index, which is time-consuming and prone to inter- and intra-observer variability. The aim of this study was to design and validate an algorithm to automatically classify RV deformation patterns.

METHODS

We developed an algorithm based on specific local characteristics from the strain curves to detect the parameters required for classification. Determination of the onset of shortening by the algorithm was compared to manual determination by an experienced operator in a dataset containing 186 RV strain curves from 26 subjects carrying a pathogenic plakophilin-2 (PKP2) mutation and 36 healthy subjects. Classification agreement between operator and algorithm was solely based on differences in onset shortening, as the remaining parameters required for classification of RV deformation patterns could be directly obtained from the strain curves.

RESULTS

The median difference between the onset of shortening determined by the experienced operator and by the automatic detector was 5.3 ms [inter-quartile range (IQR) 2.7-8.6 ms]. 96% of the differences were within 1 time frame. Both methods correlated significantly with ρ = 0.97 (P < .001). For 26 PKP2 mutation carriers, there was 100% agreement in classification between the algorithm and experienced operator.

CONCLUSION

The determination of the onset of shortening by the experienced operator was comparable to the algorithm. Our computer algorithm seems a promising method for the automatic classification of RV deformation patterns. The algorithm is publicly available at the MathWorks File Exchange.

Fibrosis in Arrhythmogenic Cardiomyopathy: The Phantom Thread in the Fibro-Adipose Tissue

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disorder, predisposing to malignant ventricular arrhythmias leading to sudden cardiac death, particularly in young and athletic patients. Pathological features include a progressive loss of myocardium with fibrous or fibro-fatty substitution. During the last few decades, different clinical aspects of ACM have been well investigated but still little is known about the molecular mechanisms that underlie ACM pathogenesis, leading to these phenotypes. In about 50% of ACM patients, a genetic mutation, predominantly in genes that encode for desmosomal proteins, has been identified. However, the mutation-associated mechanisms, causing the observed cardiac phenotype are not always clear. Until now, the attention has been principally focused on the study of molecular mechanisms that lead to a prominent myocardium adipose substitution, an uncommon marker for a cardiac disease, thus often recognized as hallmark of ACM. Nonetheless, based on Task Force Criteria for the diagnosis of ACM, cardiomyocytes death associated with fibrous replacement of the ventricular free wall must be considered the main tissue feature in ACM patients. For this reason, it urges to investigate ACM cardiac fibrosis. In this review, we give an overview on the cellular effectors, possible triggers, and molecular mechanisms that could be responsible for the ventricular fibrotic remodeling in ACM patients.

Sudden Death and Left Ventricular Involvement in Arrhythmogenic Cardiomyopathy

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disorder characterized by myocardial fibrofatty replacement and an increased risk of sudden cardiac death (SCD). Originally described as a right ventricular disease, ACM is increasingly recognized as a biventricular entity. We evaluated pathological, genetic, and clinical associations in a large SCD cohort.

METHODS

We investigated 5205 consecutive cases of SCD referred to a national cardiac pathology center between 1994 and 2018. Hearts and tissue blocks were examined by expert cardiac pathologists. After comprehensive histological evaluation, 202 cases (4%) were diagnosed with ACM. Of these, 15 (7%) were diagnosed antemortem with dilated cardiomyopathy (n=8) or ACM (n=7). Previous symptoms, medical history, circumstances of death, and participation in competitive sport were recorded. Postmortem genetic testing was undertaken in 24 of 202 (12%). Rare genetic variants were classified according to American College of Medical Genetics and Genomics criteria.

RESULTS

Of 202 ACM decedents (35.4±13.2 years; 82% male), no previous cardiac symptoms were reported in 157 (78%). Forty-one decedents (41/202; 20%) had been participants in competitive sport. The adjusted odds of dying during physical exertion were higher in men than in women (odds ratio, 4.58; 95% CI, 1.54-13.68; P=0.006) and in competitive athletes in comparison with nonathletes (odds ratio, 16.62; 95% CI, 5.39-51.24; P<0.001). None of the decedents with an antemortem diagnosis of dilated cardiomyopathy fulfilled definite 2010 Task Force criteria. The macroscopic appearance of the heart was normal in 40 of 202 (20%) cases. There was left ventricular histopathologic involvement in 176 of 202 (87%). Isolated right ventricular disease was seen in 13%, isolated left ventricular disease in 17%, and biventricular involvement in 70%. Among whole hearts, the most common areas of fibrofatty infiltration were the left ventricular posterobasal (68%) and anterolateral walls (58%). Postmortem genetic testing yielded pathogenic variants in ACM-related genes in 6 of 24 (25%) decedents.

CONCLUSIONS

SCD attributable to ACM affects men predominantly, most commonly occurring during exertion in athletic individuals in the absence of previous reported cardiac symptoms. Left ventricular involvement is observed in the vast majority of SCD cases diagnosed with ACM at autopsy. Current Task Force criteria may fail to diagnose biventricular ACM before death.

Contemporary Application of Cardiovascular Magnetic Resonance Imaging

Cardiovascular magnetic resonance imaging (CMR) is a comprehensive and versatile diagnostic and prognostic imaging modality that plays an increasingly important role in management of patients with cardiovascular disease. In this review, we discuss CMR applications in nonischemic cardiomyopathy, ischemic heart disease, arrhythmias, right ventricular diseases, and valvular heart disease. We emphasize the quantitative nature of CMR in current practice, from volumes, function, myocardial strain analysis, and late gadolinium enhancement to parametric mapping, including T1, T2, and T2* relaxation times and extracellular volume fraction assessment.

Arrhythmogenic Left Ventricular Cardiomyopathy: A Clinical and CMR Study

The clinical features, CMR characteristics and outcomes of arrhythmogenic left ventricular cardiomyopathy (ALVC), which is a very rare nonischemic cardiomyopathy, are currently not well studied. The purpose of the study is to investigate the clinical and cardiovascular magnetic resonance (CMR) imaging characteristics of arrhythmogenic left ventricular cardiomyopathy (ALVC). Fifty-three consecutive patients with ALVC were divided into two groups: ALVC patients without right ventricular (RV) involvement (n = 36, group 1) and those with RV involvement (n = 17, group 2). Clinical symptoms, cardiac electrophysiological findings, and CMR parameters (morphology, ventricular function, and myocardial fibrosis and fatty infiltration) were evaluated in both groups. The two groups showed no significant difference in age, gender, or presenting symptoms (P > 0.05). Right bundle branch block ventricular arrhythmia was less common in patients without RV involvement (50.0% vs.64.7%, P = 0.031). There were no significant differences in left ventricular function between the two groups, however right ventricular ejection fraction was significantly lower in group 2 (40.1 ± 4.0% vs. 48.7 ± 3.9%, P < 0.001). Inverse correlations of left ventricular ejection fraction with fat volume (r = −0.883, p = 0.001), late gadolinium enhancement (LGE) volume (r = −0.892, 0.013), ratio of fat/LGE (r = −0.848, p < 0.001), indexed left ventricular end diastolic volume (r = −0.877, p < 0.001) and indexed left ventricular end systolic volume (r = −0.943, p < 0.001) were all significant. ALVC is a rare disease with fibro-fatty replacement predominantly in the left ventricle, impaired left ventricular systolic function, and ventricular arrhythmias originating from the left ventricle. ALVC with right ventricular involvement may have a worse prognosis.

Left Ventricular Involvement in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy Predicts Adverse Clinical Outcomes: A Cardiovascular Magnetic Resonance Feature Tracking Study

The aim of this study was to investigate left ventricular (LV) global myocardial strain and LV involvement characteristics in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) and to evaluate their predictive value of adverse cardiac events. Sixty consecutive ARVD/C patients with a definite diagnosis of ARVD/C who underwent CMR examination and thirty-four healthy controls were enrolled retrospectively. The CMR images were analyzed for LV myocardial strain and the presence of LV involvement. The endpoint was defined as a composite of sustained ventricular tachycardia or fibrillation, cardiac death, resuscitated cardiac arrest, heart transplantation, and appropriate implantable cardioverter-defibrillator shock. LV global longitudinal (GLS), circumferential (GCS), and radial strain (GRS) were significantly impaired in ARVC/D patients compared to healthy controls (GLS: −13.89 ± 3.26% vs. −16.68 ± 2.74%, GCS: −15.65 ± 3.40% vs. −19.20 ± 2.23%, GRS: 34.57 ± 11.98% vs. 49.92 ± 12.59%; P < 0.001 for all). Even in ARVC/D patients with preserved LVEF, LV GLS, GCS and GRS were also significantly reduced than in controls. During a mean follow-up period of 4.10 ± 1.77 years, the endpoint was reached in 17 patients. LV GLS >−12.65% (HR, 3.58; 95%CI, 1.14 to 11.25; p = 0.029) and history of syncope (HR, 4.99; 95%CI, 1.88 to 13.24; p = 0.001) were the only independent predictors of cardiac outcomes. The LV myocardial deformation derived from FT CMR was significantly impaired in ARVD/C patients, and this alteration can occur before the impairment of LVEF. LV GLS >−12.65% and history of syncope were the only independent prognostic markers of adverse cardiac outcomes.

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.

Early Left Ventricular Involvement Detected by Cardiovascular Magnetic Resonance Feature Tracking in Arrhythmogenic Right Ventricular Cardiomyopathy: The Effects of Left Ventricular Late Gadolinium Enhancement and Right Ventricular Dysfunction

Background

Left ventricular (LV) involvement is common in arrhythmogenic right ventricular cardiomyopathy (ARVC). We aim to evaluate LV involvement in ARVC patients by cardiovascular magnetic resonance feature tracking.

Methods and Results

Sixty‐eight patients with ARVC and 30 controls were prospectively enrolled. ARVC patients were divided into 2 subgroups: the preserved LV ejection fraction (LVEF) group (LVEF ≥55%, n=27) and the reduced LVEF group (LVEF <55%, n=41). Cardiovascular magnetic resonance with late gadolinium enhancement (LGE) and cardiovascular magnetic resonance feature tracking were performed in all subjects. LV global and regional (basal, mid, apical) peak strain (PS) in radial, circumferential and longitudinal directions were assessed, respectively. Right ventricular global PS in three directions were also analyzed. Compared with the controls, LV global and regional PS were all significantly impaired in the reduced LVEF group (all P<0.05). However, only LV global longitudinal PS as well as mid and apical longitudinal PS were impaired in the preserved LVEF group (all P<0.05), and all these parameters were significantly associated with right ventricular global radial PS (r=−0.47, −0.47, and −0.49, respectively, all P<0.001). The reduced LVEF group showed significantly higher prevalence of LGE (95.10% versus 63.00%, P=0.002) than the preserved LVEF group. Moreover, LV radial PS was significantly reduced in LV segments with LGE (33.15±20.42%, n=46) than those without LGE (41.25±15.98%, n=386) in the preserved LVEF group (P=0.016).

Conclusions

In patients with ARVC, cardiovascular magnetic resonance feature tracking could detect early LV dysfunction, which was associated with LV myocardial LGE and right ventricular dysfunction.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia.

Postmortem cardiac magnetic resonance in sudden cardiac death

Postmortem imaging is increasingly used in forensic practice as good complementary tool to conventional autopsy investigations. Over the last decade, postmortem cardiac magnetic resonance (PMCMR) imaging was introduced in forensic investigations of natural deaths related to cardiovascular diseases, which represent the most common causes of death in developed countries. Postmortem CMR application has yielded interesting results in ischemic myocardium injury investigations and in visualizing other pathological findings in the heart. This review presents the actual state of postmortem imaging for cardiovascular pathologies in cases of sudden cardiac death (SCD), taking into consideration both the advantages and limitations of PMCMR application.

The Prognostic Value of Right Ventricular Deformation Imaging in Early Arrhythmogenic Right Ventricular Cardiomyopathy

OBJECTIVES

The aim of this study was to investigate the prognostic value of echocardiographic deformation imaging in arrhythmogenic right ventricular cardiomyopathy (ARVC) to optimize family screening protocols.

BACKGROUND

ARVC is characterized by variable disease expressivity among family members, which complicates family screening protocols. Previous reports have shown that echocardiographic deformation imaging detects abnormal right ventricular (RV) deformation in the absence of established disease expression in ARVC.

METHODS

First-degree relatives of patients with ARVC were evaluated according to 2010 task force criteria, including RV deformation imaging (n = 128). Relatives fulfilling structural task force criteria were excluded for further analysis. At baseline, deformation patterns of the subtricuspid region were scored as type I (normal deformation), type II (delayed onset, decreased systolic peak, and post-systolic shortening), or type III (systolic stretching and large post-systolic shortening). The final study population comprised relatives who underwent a second evaluation during follow-up. Disease progression was defined as the development of a new 2010 task force criterion during follow-up that was absent at baseline.

RESULTS

Sixty-five relatives underwent a second evaluation after a mean follow-up period of 3.7 ± 2.1 years. At baseline, 28 relatives (43%) had normal deformation (type I), and 37 relatives (57%) had abnormal deformation (type II or III) in the subtricuspid region. Disease progression occurred in 4% of the relatives with normal deformation at baseline and in 43% of the relatives with abnormal deformation at baseline (p < 0.001). Positive and negative predictive values of abnormal deformation were, respectively, 43% (95% confidence interval: 27% to 61%) and 96% (95% confidence interval: 82% to 100%).

CONCLUSIONS

Normal RV deformation in the subtricuspid region is associated with absence of disease progression during nearly 4-year follow-up in relatives of patients with ARVC. Abnormal RV deformation seems to precede the established signs of ARVC. RV deformation imaging may potentially play an important role in ARVC family screening protocols.

Diagnostic and therapeutic strategies for arrhythmogenic right ventricular dysplasia/cardiomyopathy patient

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a rare inherited heart muscle disease characterized by ventricular tachyarrhythmia, predominant right ventricular dysfunction, and sudden cardiac death. Its pathophysiology involves close interaction between genetic mutations and exposure to physical activity. Mutations in genes encoding desmosomal protein are the most common genetic basis. Genetic testing plays important roles in diagnosis and screening of family members. Syncope, palpitation, and lightheadedness are the most common symptoms. The 2010 Task Force Criteria is the standard for diagnosis today. Implantation of a defibrillator in high-risk patients is the only therapy that provides adequate protection against sudden death. Selection of patients who are best candidates for defibrillator implantation is challenging. Exercise restriction is critical in affected individuals and at-risk family members. Antiarrhythmic drugs and ventricular tachycardia ablation are valuable but palliative components of the management. This review focuses on the current diagnostic and therapeutic strategies in ARVD/C and outlines the future area of development in this field.

Arrhythmogenic Cardiomyopathy in 2018-2019: ARVC/ALVC or Both?

Arrhythmogenic cardiomyopathy (ACM) is now commonly used to describe any form of non-hypertrophic, progressive cardiomyopathy characterised by fibrofatty infiltration of the ventricular myocardium. Right ventricular (RV) involvement refers to the classical arrhythmogenic right ventricular cardiomyopathy, but left ventricular, or bi-ventricular involvement are now recognised. ACM is mostly hereditary and associated with mutations in genes encoding proteins of the intercalated disc. ACM classically manifests as ventricular arrhythmias, and sudden death may be the first presentation of the disease. Heart failure is seen with advanced stages of the disease. Diagnosis can be challenging due to variable expressivity and incomplete penetrance, and is guided by established Taskforce criteria that incorporate electrical features (12-lead electrocardiography (ECG), features of ventricular arrhythmias), structural features (on imaging via echo and cardiac magnetic resonance imaging [MRI]), tissue characteristics (via biopsy), and familial/genetic evaluation. Electrical abnormalities may precede structural alterations, which also make diagnosis challenging, especially in differentiating ACM from other conditions such as benign right ventricular arrhythmias, channelopathies such as Brugada, or the Athlete's Heart. Genetic testing is critical in identifying familial mutations and initiating cascade testing, but finds a pathogenic mutation in only ∼50% of patients. Some critical genotype-phenotype correlations do exist and may help guide risk stratification and give clues to disease progression. Therapeutic strategies include restriction from high endurance and competitive sports, ß-blockers, antiarrhythmic drugs, heart failure medications, implantable cardioverter-defibrillators and combined endocardial/epicardial catheter ablation. Ablation has emerged as the treatment of choice for recurrent ventricular arrhythmias in ACM. This state-of-the-art review outlines the pathogenesis, diagnosis and treatment of ACM in the contemporary era.

Right ventricular function in elite male athletes meeting the structural echocardiographic task force criteria for arrhythmogenic right ventricular cardiomyopathy

Athlete pre-participation screening is focused on detecting pathological conditions like arrhythmogenic right ventricular cardiomyopathy (ARVC). The diagnosis of ARVC is established by applying the revised 2010 ARVC Task Force Criteria (TFC) that assesses RV structure and function. Some athletes may meet structural TFC without having ARVC but we do not know the consequences for RV function. This study compared RV structural and functional indices in male athletes that meet the structural TFC (MTFC) for ARVC and those that do not (NMTFC). We recruited 214 male elite athletes. All participants underwent 2D, Doppler, tissue Doppler and strain (ε) echocardiography with a focused and comprehensive assessment of the right heart. Athletes were grouped on RV structural data: MTFC n = 34; NMTFC n = 180. Functional data were compared between groups. By selection, MTFC had larger absolute and scaled RV outflow tract (RVOT) diameter compared to NMTFC (P ˂0.05) but these athletes did not develop a proportional increase in the RV inflow dimensions. There was no difference in global conventional RV systolic function between both groups however, there was significantly lower global RV ε in athletes that MTFC which can be explained, in part, by the RVOT dimension.

Compound heterozygous mutations in desmoplakin associated with skin fragility, follicular hyperkeratosis, alopecia, and nail dystrophy

Desmoplakin mutations are associated with a wide variety of phenotypes affecting the skin, nails, hair, and heart. A 21-month-old boy was born with multiple erosions resembling epidermolysis bullosa, complete alopecia, nail dystrophy, palmoplantar keratoderma, and areas of follicular hyperkeratosis. He was found to have two heterozygous mutations in the desmoplakin gene: c.478 C>T in exon 4 (p.Arg160X) and c.3630T>A in exon 23 (Tyr1210X). This case expands the clinical spectrum associated with desmoplakin mutations and highlights a mutation in exon 23 that has not been previously reported in the literature.

Interplay of cell-cell contacts and RhoA/MRTF-A signaling regulates cardiomyocyte identity

Cell-cell and cell-matrix interactions guide organ development and homeostasis by controlling lineage specification and maintenance, but the underlying molecular principles are largely unknown. Here, we show that in human developing cardiomyocytes cell-cell contacts at the intercalated disk connect to remodeling of the actin cytoskeleton by regulating the RhoA-ROCK signaling to maintain an active MRTF/SRF transcriptional program essential for cardiomyocyte identity. Genetic perturbation of this mechanosensory pathway activates an ectopic fat gene program during cardiomyocyte differentiation, which ultimately primes the cells to switch to the brown/beige adipocyte lineage in response to adipogenesis-inducing signals. We also demonstrate by in vivo fate mapping and clonal analysis of cardiac progenitors that cardiac fat and a subset of cardiac muscle arise from a common precursor expressing Isl1 and Wt1 during heart development, suggesting related mechanisms of determination between the two lineages.

Arrhythmogenic cardiomyopathy: pathology, genetics, and concepts in pathogenesis

Arrhythmogenic cardiomyopathy (ACM) is a rare, heritable heart disease characterized by fibro-fatty replacement of the myocardium and a high degree of electric instability. It was first thought to be a congenital disorder, but is now regarded as a dystrophic heart muscle disease that develops over time. There is no curative treatment and current treatment strategies focus on attenuating the symptoms, slowing disease progression, and preventing life-threatening arrhythmias and sudden cardiac death. Identification of mutations in genes encoding desmosomal proteins and in other genes has led to insights into the disease pathogenesis and greatly facilitated identification of family members at risk. The disease phenotype is, however, highly variable and characterized by incomplete penetrance. Although the reasons are still poorly understood, sex, endurance exercise and a gene-dosage effect seem to play a role in these phenomena. The discovery of the genes and mutations implicated in ACM has allowed animal and cellular models to be generated, enabling researchers to start unravelling it's underlying molecular mechanisms. Observations in humans and in animal models suggest that reduced cell-cell adhesion affects gap junction and ion channel remodelling at the intercalated disc, and along with impaired desmosomal function, these can lead to perturbations in signalling cascades like the Wnt/β-catenin and Hippo/YAP pathways. Perturbations of these pathways are also thought to lead to fibro-fatty replacement. A better understanding of the molecular processes may lead to new therapies that target specific pathways involved in ACM.