Right heart strain in arrhythmogenic right ventricular cardiomyopathy: Implications for cardiovascular outcome

INTRODUCTION

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by progressive myocardial dysfunction and associated with an increased risk of major cardiovascular events.

AIMS

To determine right heart strain (ventricular and atrial global longitudinal strain (RVGLS and RAGLS)) in patients with definite ARVC and its association with adverse events during follow-up.

METHODS

RVGLS and RAGLS were analysed in focused right heart apical views from 70 patients using TomTec ImageArena and association with a composite endpoint (sustained ventricular arrhythmia and cardiovascular death) was determined.

RESULTS

Over a median follow-up duration of 4.9 years, 26 (37%) patients met the endpoint. RVGLS was significantly impaired in the event group (-11.5 [-13.3 - -10.2]%) versus the no-event group (-15.8 [-17.1 - -14.5]%, P < 0.001), and so was RAGLS (22.8 [21.4 - 27.4]% vs. 31.5 [25.1 - 39.6]%, respectively, P < 0.001). In Cox regression, RVGLS (HR 1.36, P < 0.001) and RAGLS (HR 0.92, P = 0.002) were associated with higher risk of adverse events. In multivariable Cox regression models, RVGLS and RAGLS remained independent of and were incremental to age, gender, and conventional RV parameters, and model fit was improved when RVGLS and RAGLS were applied together rather than alone.

CONCLUSIONS

RVGLS and RAGLS are more impaired in patients with adverse events and associated with adverse events independent of age, gender, and conventional RV parameters. When RVGLS and RAGLS are applied together, prediction models are improved suggesting that right heart strain may form part of the echocardiographic routine protocol in patients with ARVC.

Real World Data from Catheter Ablation of Ventricular Tachycardias and Premature Ventricular Complexes in a Tertiary Care Center

Background: Catheter ablation in patients with ventricular arrhythmias (VA), such as ventricular tachycardias (VT) or frequent premature ventricular complexes (PVC), is increasingly considered an effective and safe therapy when performed in experienced centers. This study sought to determine acute success rates and complication rates of ablation procedures for patients with VA in a Swiss tertiary care center. Methods: All patients who underwent ablation therapy for VT and PVC at the University Heart Center in Zurich, Switzerland, between March 2012 and April 2017 were included in this analysis. Results: A total of 120 patients underwent catheter ablation for VT and PVC (69 and 51, respectively). Seventy percent of patients were male, and the mean age was 55.3 years. The most common indication for ablation was high PVC burden (47.5%), followed by paroxysmal VT (38.3%), ICD shocks (23.3%), incessant VT (12.5%), electrical storm (7.5%), and syncope (3.3%). Acute success rates for VT and PVC ablations were 94.2% and 92.2%, respectively. Rates for complications (including major and minor) for VT and PVC were 10.1% and 7.8%, respectively. Complications occurred only in patients with structural heart disease; no complications were noted in structurally normal hearts. Conclusions: Our results suggest that catheter ablation for VT and PVC has high acute success rates with a reasonable risk for complications in the setting of tertiary care centers, comparable to those reported in other studies.

Catecholaminergic Polymorphic Ventricular Tachycardia: Multiple Clinical Presentations of a Genetically Determined Disease

BACKGROUND

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare, inherited heart rhythm disorder that is caused by variants in genes responsible for cardiac calcium homeostasis. The aim of this study was to analyze different genotype-specific clinical manifestations of this disease.

METHODS AND RESULTS

We analyzed five CPVT cases from our institution in the context of specific patient characteristics and genotype-phenotype correlations. In this cohort, three of the index patients were male. The median age at diagnosis was 11 (11-30) years, and median age at disease onset was 12 (12-33) years. Four index patients suffered from syncope, while one female index patient suffered from out-of-hospital cardiac arrest. Two index patients experienced concomitant atrial flutter and atrial fibrillation. Three patients received an implantable cardioverter defibrillator and one patient received an event recorder. All index patients had causative genetic variants in the RYR2-gene.

CONCLUSIONS

This study presents various phenotypic presentations of patients with CPVT harboring different pathogenic variants in the RYR2 gene, some of which have not previously been described in published studies. Syncope was the most prevalent symptom on admission. Adjustment of beta-blocker therapy may be necessary due to side effects. Moreover, our work further highlights the common occurrence of atrial tachyarrhythmias in these patients.

The effect of first step right atrial mapping (FRAM) on ablation duration and fluoroscopy exposure during cavotricuspid isthmus ablation of atrial flutter

Aim

To investigate the clinical significance of right atrial mapping prior to cavotricuspid isthmus (CTI) ablation in patients with typical atrial flutter (AFL).

Methods

Clinical and ablation parameters were retrospectively assessed and compared in patients undergoing CTI ablation with or without a first-step right atrial mapping (FRAM) by using the CARTO 3D mapping system.

Results

CTI block by radiofrequency ablation (RFA) was achieved in all 143 patients. In the FRAM group there was a shorter ablation duration and fluoroscopy exposure compared with the non-FRAM group. CHA₂DS₂-VASc score was associated with higher ablation durations, more ablation applications and increased fluoroscopy exposure. Body mass index (BMI) was associated with longer ablation duration and more ablation applications. Furthermore, patients with reduced left ventricular ejection fraction (LVEF) had longer ablation durations and more fluoroscopy exposure. One patient in the non-FRAM group developed cardiac effusion after ablation. None of the patients had recurrence after 6 months of follow-up.

Conclusions

Patients with high BMI, high CHA₂DS₂-VASc score and reduced LVEF may benefit from the FRAM approach by reducing ablation duration, number of ablation applications and fluoroscopy exposure.

Evolution and triggers of defibrillator shocks in patients with arrhythmogenic right ventricular cardiomyopathy

INTRODUCTION

Implantable cardioverter-defibrillators (ICDs) can prevent sudden cardiac death due to ventricular arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). The aim of our study was to assess the cumulative burden, evolution and potential triggers of appropriate ICD shocks during long-term follow-up, which may help to reduce and further refine individual arrhythmic risk in this challenging disease.

METHODS

This retrospective cohort study included 53 patients with definite ARVC according to the 2010 Task Force Criteria from the multicentre Swiss ARVC Registry with an implanted ICD for primary or secondary prevention. Follow-up was conducted by assessing all available patient records from patient visits, hospitalisations, blood samples, genetic analysis, as well as device interrogation and tracings.

RESULTS

Fifty-three patients (male 71.7%, mean age 43±2.2 years, genotype positive 58.5%) were analysed during a median follow-up of 7.9 (IQR 10) years. In 29 (54.7%) patients, 177 appropriate ICD shocks associated with 71 shock episodes occurred. Median time to first appropriate ICD shock was 2.8 (IQR 3.6) years. Long-term risk of shocks remained high throughout long-term follow-up. Shock episodes occurred mainly during daytime (91.5%, n=65) and without seasonal preference. We identified potentially reversible triggers in 56 of 71 (78.9%) appropriate shock episodes, the main triggers representing physical activity, inflammation and hypokalaemia.

CONCLUSION

The long-term risk of appropriate ICD shocks in patients with ARVC remains high during long-term follow-up. Ventricular arrhythmias occur more often during daytime, without seasonal preference. Reversible triggers are frequent with the most common triggers for appropriate ICD shocks being physical activity, inflammation and hypokalaemia in this patient population.

A Novel Heterozygous Desmoplakin Variant Causes Cardiocutaneous Syndrome with Arrhythmogenic Cardiomyopathy and Palmoplantar Keratosis

Cardiocutaneous syndrome (CCS) is often caused by genetic variants in desmoplakin (DSP) in the presence of thick calluses on the hands and soles of the feet (palmoplantar keratoderma) in combination with arrhythmogenic cardiomyopathy. In this case report, we describe a 58-year-old man presenting with a history of cardiomyopathy with recurrent sustained ventricular tachycardia and palmoplantar keratosis. The cardiological evaluation showed biventricular cardiomyopathy, and repeated genetic testing identified a novel DSP variant. Repeated genetic testingis clinically meaningful in patients with a high probability of a specific inherited cardiac disease, such as CCS, particularly if molecular screening has been performed in the pre-NGS era with an incomplete NGS panel or outdated technology as presented in this case report.

Identifying proteomic profiles as indicators of disease severity in arrhythmogenic cardiomyopathy

Introduction

Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disease characterized by progressive fibrofatty replacement of the myocardium and ventricular arrhythmias. Biventricular (BiV) involvement may lead to heart failure. This study aimed to investigate characteristic proteomic patterns in plasma of ACM patients, and correlated them with clinical outcome as well as physical exercise, to assess if key soluble molecules may serve as specific biomarkers for ACM, and whether mechanical stress induced by physical exercise may alter proteomic patterns in ACM patients.

Methods

In 38 ACM patients clinical parameters and major adverse cardiovascular events (MACE defined as presence of sustained ventricular tachycardia, ventricular fibrillation, appropriate therapy from implantable cardioverter defibrillator, sudden cardiac death, death related to end-stage heart failure or cardiac transplant) were obtained prospectively during a mean follow-up period of 36 months. All patients received genetic testing using next generation DNA sequencing. Plasma protein expression was analysed using the Proximity Extension Assay (PEA) technology, where a pair of oligonucleotide-labelled antibody probe binds to each targeted protein. In a subgroup of 11 patients blood was drawn immediately before and 3 hours after standardised bicycle exercise testing, and plasma protein expression was compared.

Results

12 patients had ACM with BiV involvement, and 26 patients had isolated right ventricular (RV) involvement. During the follow-up period, 34 patients had a MACE (30% with RV and 14% with BiV). Over 360 proteins were assessed in all ACM patients and compared to 24 healthy controls. The proteomic signature of ACM patients differed significantly compared to controls, and 32 proteins were upregulated in ACM (Figure 1). The proteomic profiles of patients with RV involvement also differed from those with BiV involvement. Most importantly, after exercise, over 40 proteins were upregulated specifically in ACM patients compared to controls, including key pro-inflammatory, adipogenic molecules and also markers of cardiac fibrosis.

Conclusion

Our study shows that ACM patients with RV and BiV involvement have different plasma proteomic profiles compared to healthy controls. Furthermore we were able to demonstrate that, specifically in ACM patients, several pro-inflammatory pathways are upregulated after exercise compared to healthy controls, further elucidating the molecular pathways associated with arrhythmogenicity and disease progression and highlighting the key role of physical stress. Our results may enable the identification of potential future biomarkers for diagnosis and risk stratification and may pave the way for personalized patient specific treatments.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Baugarten Foundation ZurichSwiss National Foundation

Tissue Doppler echocardiography and outcome in arrhythmogenic right ventricular cardiomyopathy

AIMS

This study aimed at investigating whether tissue Doppler imaging (TDI) is associated with adverse events in arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS AND RESULTS

Transthoracic echocardiography was performed in 72 patients with definite (n = 63) or borderline (n = 9) ARVC diagnosed according to the 2010 Task Force Criteria and included in the prospective Zurich ARVC registry. Myocardial peak systolic tissue velocity (S') was measured by TDI at lateral tricuspid (tricuspid S'), medial mitral (septal S'), and lateral mitral annulus (lateral S'). Association of echocardiographic parameters with outcome was assessed by univariable Cox regression. During a median follow-up of 4.9 ± 2.6 years, 6 (8.3%) patients died of cardiovascular cause or received heart transplantation and 21 (29.2%) patients developed sustained ventricular arrhythmia. Tricuspid, septal, and lateral S' were lower in patients who died (p = 0.001; p < 0.001; p = 0.008; respectively), while tricuspid and septal S' were lower in those with ventricular arrhythmia (p = 0.001; p = 0.008; respectively). There was a significant association of tricuspid, septal, and lateral S' with mortality (HR = 1.61, p = 0.011; HR = 2.15, p = 0.007; HR = 1.67, p = 0.017; respectively), while tricuspid and septal S' were associated with ventricular arrhythmia (HR = 1.20, p = 0.022; HR = 1.37, p = 0.004; respectively). Kaplan-Meier analyses demonstrated a higher freedom from mortality with tricuspid S' >8 cm/s (p = 0.001) and from ventricular arrhythmia with S' >10.5 cm/s (p = 0.021).

CONCLUSIONS

This study demonstrates that TDI provides information on the ARVC phenotype, is associated with adverse events in ARVC patients, and differentiates between patients with and without adverse events.

Novel Risk Prediction Model to Determine Adverse Heart Failure Outcomes in Arrhythmogenic Right Ventricular Cardiomyopathy

Background

Patients with arrhythmogenic right ventricular cardiomyopathy are at risk for life‐threatening ventricular tachyarrhythmias, but progressive heart failure (HF) may occur in later stages of disease. This study aimed to characterize potential risk predictors and develop a model for individualized assessment of adverse HF outcomes in arrhythmogenic right ventricular cardiomyopathy.

Methods and Results

Longitudinal and observational cohorts with 290 patients with arrhythmogenic right ventricular cardiomyopathy from the Fuwai Hospital in Beijing, China, and 99 patients from the University Heart Center in Zurich, Switzerland, with follow‐up data were studied. The primary end point of the study was heart transplantation or death attributable to HF. The model was developed by Cox regression analysis for predicting risk and was internally validated. During 4.92±3.03 years of follow‐up, 48 patients reached the primary end point. The determinants of the risk prediction model were left ventricular ejection fraction, serum creatinine levels, moderate‐to‐severe tricuspid regurgitation, and atrial fibrillation. Implantable cardioverter‐defibrillators did not reduce the occurrence of adverse HF outcomes.

Conclusions

A novel risk prediction model for arrhythmogenic right ventricular cardiomyopathy has been developed using 2 large and well‐established cohorts, incorporating common clinical parameters such as left ventricular ejection fraction, serum creatinine levels, tricuspid regurgitation, and atrial fibrillation, which can identify patients who are at risk for terminal HF events, and may guide physicians to assess individualized HF risk and to optimize management strategies.

Efficacy of Catheter Ablation for Atrial Arrhythmias in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy-A Multicenter Study

Background: Atrial arrhythmias are present in up to 20% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Catheter ablation (CA) is an effective treatment for atrial arrhythmias in the general population. Data regarding CA for atrial arrhythmias in ARVC are scarce. Objective: To assess the safety and efficacy of CA for atrial arrhythmias in patients with ARVC. Methods: In this international collaborative effort, all patients with a definite diagnosis of ARVC undergoing CA for atrial fibrillation (AF), focal atrial tachycardia (AT), or cavotricuspid isthmus (CTI)-dependent atrial flutter (AFl) were extracted from twelve ARVC registries. Demographic, periprocedural, and long-term arrhythmic outcome data were collected. Results: Thirty-seven patients were enrolled in the study (age 50.2 ± 16.6 years, male 84%, CHA₂DS₂VASc 1 (1,2), HAS-BLED 0 (0–2)). The arrhythmia leading to CA was AF in 23 (62%), focal left AT in 5 (14%), and CTI-dependent AFl in 9 (24%). Acute procedural success was achieved in all procedures but one (n = 1 focal left AT; 97% acute success). The median follow-up period was 27 (13–67) months, and 96%, 74%, and 61% of patients undergoing AF ablation were free from any atrial arrhythmia recurrence after a single procedure at 6 months, 12 months, and last follow-up, respectively. After focal AT ablation, freedom from atrial arrhythmia recurrence was 80%, 80%, and 60% at 6 months, 12 months, and last follow-up, respectively. All patients undergoing CTI ablation were free from atrial arrhythmia recurrences at 6 months, with 89% single-procedural arrhythmic freedom at last follow-up. One major complication (2.7%; PV stenosis requiring PV stenting) occurred. Conclusions: CA is safe and effective in managing atrial arrhythmias in patients with ARVC, with success rates comparable to the general population.

Distinctive characteristics of his bundle potentials in patients with atrioventricular nodal reentrant tachycardia

BACKGROUND

His bundle (HB) potentials vary in amplitude and duration in patients with and without slow pathways. The aim of this study was to determine the characteristics of HB potentials and to elucidate whether they can provide clues for identification of slow pathway (SP).

METHODS

The present research prospectively studied the electrophysiological findings of 162 patients with symptomatic atrioventricular nodal reentrant tachycardia (AVNRT) due to slow-fast or fast-slow type and atrioventricular reentrant tachycardia (AVRT). Maximal HB potential (HBmax, HB with the highest amplitude) among HB cloud was recorded in both groups. For AVNRT patients, the following were measured: (1) AH interval at the "jump" during programmed atrial stimulation (A2H2, taken as a reflection of SP conduction time); (2) Distance from HBmax to the successful SP ablation site (HBmax-ABL) and from HBmax to the ostium of coronary sinus (HBmax-CSO).

RESULTS

HBmax was 0.29 ± 0.10 mV in AVNRT patients, whereas it was 0.17 ± 0.05 mV in AVRT group (p < 0.0001). Likewise, the HBmax duration was 22 ± 5 ms in AVNRT group and 16 ± 3 ms in AVRT group (p < 0.0001). The area under the ROC curve of HBmax amplitude in AVNRT patients was 0.86 and the optimal HBmax cut-off to predict AVNRT was ≥ 0.22 mV with a sensitivity of 0.78 and specificity of 0.84. HBmax-CSO was positively correlated with HBmax-ABL, and HBmax-ABL was positively correlated with A2H2.

CONCLUSIONS

HBmax amplitudes were higher and durations longer in patients with AVNRT, as compared to those with AVRT. Moreover, the distance between HBmax and successful ablation site was positively correlated with the SP conduction time and with the distance from HBmax to the CS ostium.

The Link Between Sex Hormones and Susceptibility to Cardiac Arrhythmias: From Molecular Basis to Clinical Implications

It is well-known that gender is an independent risk factor for some types of cardiac arrhythmias. For example, males have a greater prevalence of atrial fibrillation and the Brugada Syndrome. In contrast, females are at increased risk for the Long QT Syndrome. However, the underlying mechanisms of these gender differences have not been fully identified. Recently, there has been accumulating evidence indicating that sex hormones may have a significant impact on the cardiac rhythm. In this review, we describe in-depth the molecular interactions between sex hormones and the cardiac ion channels, as well as the clinical implications of these interactions on the cardiac conduction system, in order to understand the link between these hormones and the susceptibility to arrhythmias.

Impact of genetic reclassification on ARVC diagnosis based on the 2010 task force criteria

Introduction

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited condition, which is associated with potentially life-threatening ventricular arrhythmias in the young. Approximately 60% of patients carry a possibly disease-causing genetic variant.

Purpose

The aim of this study was to investigate the impact of the 2015 American College of Medical Genetics (ACMG) Criteria on ARVC diagnosis based on the 2010 Modified Task Force Criteria (TFC).

Methods

The study included 79 patients from the Swiss ARVC Registry who harbored a genetic variant deemed to be associated with the disease at initial screening, and classified them as definite, borderline or possible ARVC. Every variant found was re-classified on Varsome Genetics, based on the 2015 ACMG Criteria. Clinical information was then assessed at last available follow-up of every patient and ARVC diagnosis was reclassified based on the newest genetic evidence available.

Results

In 42 out of 79 patients (53.2%), genetic variants were reclassified. Out of these, 33 variants (41.8%) were downgraded from pathogenic (P) / likely pathogenic (LP) to either variants of unknown significance (VUS) or benign (B) / likely benign (LB). Three patients (3.8%) were upgraded from VUS / LP to P. Out of the 12 variants initially classified as VUS, 9 (75%) were reclassified as B or LB. Overall, 13 patients (16.5%) were downgraded from their initial diagnosis (11 from definite to borderline and 2 from borderline to possible).

Conclusion

A significant proportion of patients with ARVC diagnosed based on the 2010 TFC were reclassified when the 2015 ACMG Criteria were taken into consideration. These findings may have clinical consequences, particularly for genetic cascade screening of family members of ARVC patients and necessitate reassessment of genetic variants of index patients who were previously diagnosed with ARVC.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): University Hospital Zurich

Novel plasma biomarkers in arrhythmogenic cardiomyopathy: the role of ST2 and GDF-15 in predicting biventricular involvement

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease characterized by fibrofatty replacement of the myocardium and ventricular arrhythmias. Biventricular (BiV) involvement in ARVC may lead to heart failure.

Purpose

This study aimed to investigate the role of novel plasma biomarkers soluble (s)ST2, Galectin-3 (Gal-3) and GDF-15 in predicting BiV involvement and adverse outcomes in ARVC patients.

Methods

ARVC patients from two independent cohorts were studied. 108 patients were included from the discovery cohort and 47 patients were included from a second validation cohort. All patients had a definite ARVC diagnosis at time of blood withdrawal. sST2, Gal-3 and GDF-15 were independently correlated with NT-proBNP, left ventricular (LV) ejection fraction, late gadolinium enhancement by cardiac magnetic resonance (CMR) imaging and clinical outcome.

Results

ARVC patients with LV involvement had higher levels of sST2 and GDF-15 as compared to controls and patients with isolated right ventricular involvement. sST2 and GDF-15 significantly correlated to late gadolinium enhancement on CMR and also correlated to adverse heart failure outcomes. Gal-3 was elevated in ARVC patients with and without LV involvement as compared to controls. The combined use of the three biomarkers (NT-proBNP, sST2 and GDF-15) showed the best performance in predicting LV involvement in both the discovery and the validation cohort. Plasma drawn from coronary arteries and coronary sinus showed a transmyocardial elevation of sST2.

Conclusion

Our study shows that sST2 and GDF-15 may predict BiV involvement and the combined use of NT-proBNP, sST2 and GDF-15 shows the best prediction of LV involvement in ARVC. Transmyocardial elevation of sST2 suggests that this biomarker is produced by myocardial tissue in ARVC.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Fuwai ARVC Program was supported by CAMS Innovation Fund for Medical Sciences and the National Natural Science Foundation of China, Zurich ARVC Program was supported by grants from the Schwyzer Foundation and Baugarten Foundation

[CME ECC 66: Torsade de Pointes: The Danger of a Rotating Heart Axis]

CME ECC 66: Torsade de Pointes: The Danger of a Rotating Heart Axis Abstract. Torsade de pointes tachycardia is a potentially life-threatening heart rhythm disorder, caused by prolongation of the QT-interval resulting in triggered activity. This QT-prolongation can be congenital or acquired. If acquired, it is mainly caused by pharmacological therapy. The hallmark of torsade de pointes is an undulating QRS axis with a twist of the QRS complex around the ECG's baseline. Often, this polymorphic ventricular tachycardia is self-limiting, but degeneration into ventricular fibrillation is possible, which makes torsade de pointes tachycardia dangerous. This article aims to provide insights into etiology, diagnostics, prevention and management of this heart rhythm disorder.

Clinical predictors of left ventricular involvement in arrhythmogenic right ventricular cardiomyopathy

AIM

The impact of clinical characteristics for predicting patterns of ventricular involvement in arrhythmogenic right ventricular cardiomyopathy (ARVC) are not well defined. The aims of this study were to characterize different patterns of ventricular involvement in patients with ARVC and to stratify them based on clinical characteristics exercise and underlying genetic mutations.

METHODS

Sixty-four patients with definite ARVC from the Swiss ARVC Registry were enrolled. Right and left ventricular functions were assessed at baseline and most recent follow-up. All patients received genetic testing. Serum high-sensitivity cardiac Troponin T (hs-cTNT) and N-terminal of pro-brain natriuretic peptide (NT-proBNP) were determined at baseline.

RESULTS

Thirty-five patients (55%) had isolated right ventricular (RV) involvement, 12 patients (19%) had biventricular (BiV) involvement at baseline and 17 patients (26%) had no left ventricular (LV) involvement at baseline, but revealed new onset LV involvement at mean follow-up of 7.5 years. Patients with BiV involvement at baseline harbored significantly more desmoplakin and multiple mutations and patients with new-onset LV involvement at follow-up frequently showed non-desmosomal mutations. Patients engaging in competitive sports more often showed LV involvement during follow-up. Baseline hs-cTNT and NT-proBNP levels were higher in patients developing BiV involvement.

CONCLUSION

Multiple mutations are more common in ARVC patients with BiV involvement. Competitive exercise is associated with disease progression resulting in BiV involvement. Hs-cTNT and NT-proBNP are elevated in patients with BiV involvement and may help to identify ARVC patients at risk for developing BiV disease.

[CME ECG 66/Answers: Torsade de Pointes: The Danger of a Rotating Heart Axis]

CME ECG 66/Answers: Torsade de Pointes: The Danger of a Rotating Heart Axis Abstract. Torsade de pointes tachycardia is a potentially life-threatening heart rhythm disorder, caused by prolongation of the QT interval resulting in triggered activity. This QT prolongation can be congenital or acquired. If acquired, it is mainly caused by pharmacological therapy. The hallmark of torsade de pointes is an undulating QRS axis with a twist of the QRS complex around the ECG's baseline. Often, this polymorphic ventricular tachycardia is self-limiting, but degeneration into ventricular fibrillation is possible, which makes torsade de pointes tachycardia dangerous. This article aims to provide insights into etiology, diagnostics, prevention and management of this heart rhythm disorder.

An autoantibody identifies arrhythmogenic right ventricular cardiomyopathy and participates in its pathogenesis

Aims

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by right ventricular myocardial replacement and life-threatening ventricular arrhythmias. Desmosomal gene mutations are sometimes identified, but clinical and genetic diagnosis remains challenging. Desmosomal skin disorders can be caused by desmosomal gene mutations or autoantibodies. We sought to determine if anti-desmosome antibodies are present in subjects with ARVC.

Methods and results

We evaluated ARVC subjects and controls for antibodies to cardiac desmosomal cadherin proteins. Desmoglein-2 (DSG2), desmocollin-2, and N-cadherin proteins on western blots were exposed to sera, in primary and validation cohorts of subjects and controls, as well as the naturally occurring Boxer dog model of ARVC. We identified anti-DSG2 antibodies in 12/12 and 25/25 definite ARVC cohorts and 7/8 borderline subjects. Antibody was absent in 11/12, faint in 1/12, and absent in 20/20 of two control cohorts. Anti-DSG2 antibodies were present in 10/10 Boxer dogs with ARVC, and absent in 18/18 without. In humans, the level of anti-DSG2 antibodies correlated with the burden of premature ventricular contractions (r = 0.70), and antibodies caused gap junction dysfunction, a common feature of ARVC, in vitro. Anti-DSG2 antibodies were present in ARVC subjects regardless of whether an underlying mutation was identified, or which mutation was present. A disease-specific DSG2 epitope was identified.

Conclusion

Anti-DSG2 antibodies are a sensitive and specific biomarker for ARVC. The development of autoimmunity as a result of target-related mutations is unique. Anti-DSG2 antibodies likely explain the cardiac inflammation that is frequently identified in ARVC and may represent a new therapeutic target.

P3689Association of echocardiographic progression and genetic profile in arrhythmogenic right ventricular cardiomyopathy

Background

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is frequently associated with mutations in genes coding for desmosomal proteins. In this study, we investigated the association of genetic status with ARVC progression as defined by echocardiographic parameters.

Methods

We tested 62 ARVC patients for their genetic profile. Accordingly, they were grouped in mutation positive (48 (77%) patients; median age 48.5 years; 33 (69%) males), and mutation negative (14 (23%) patients; median age 45 years; 10 (71%) males). Prevalent mutations were Desmoglein-2 (DSG2) in 16 (26%), Desmoplakin (DSP) in 14 (23%), and Plakophilin-2 (PKP2) in 9 (15%) patients.

Results

At baseline, there were no significant differences in clinical characteristics between the two groups. Patients were followed-up for a median time period of 1420 days, and there was no significant difference in the duration of follow-up between the two groups (p=0.05).

In the mutation positive group, there was a significant increase in right ventricular end-diastolic area (p=0.002), right atrial short (p=0.008) and long (p=0.002) diameter, left atrial diameter (p=0.014), and a decrease in left ventricular ejection fraction (p=0.014) during follow up. Right ventricular functial parameters did not change significantly (tricuspid annular plane systolic excursion: p=0.24; fractional area change: p=0.088).

In the mutation negative group, none of the aforementioned echocardiographic findings exhibited any significant difference during follow-up: right ventricular end-diastolic area (p=0.1); right atrial short (p=0.7) and long (p=0.9) diameter, left atrial diameter (p=0.6), and left ventricular ejection fraction (p=0.3). Similarly, right ventricular functional parameters did not change significantly (tricuspid annular plane systolic excursion: p=0.77; fractional area change: p=0.80. Results are summarized in the figure.

Change in echocardiographic findings.

Conclusions

There is a strong association between echocardiographic progression of ARVC phenotype and the presence of a pathogenic mutation. Such mutations should be searched in all patients with an ARVC phenotype, and mutation positive individuals should be followed-up in shorter intervals.

Clinical Characteristics of Patients with a Right Ventricular Thrombus in Arrhythmogenic Right Ventricular Cardiomyopathy

Background Thrombus formation within the left ventricle (LV) is a well-known clinical entity and is often associated with underlying myocardial disease, whereas right ventricular (RV) thrombi are rarely observed. This study aimed to investigate the clinical characteristics of patients with arrhythmogenic RV cardiomyopathy (ARVC) who developed an RV thrombus.

Methods and Results This study included patients with an RV thrombus from the ARVC databases of the University Heart Center in Zurich, Switzerland, and the Fuwai Hospital in Beijing, China. In total, there were 13 ARVC patients who had an RV thrombus detected. The mean age was 33 ± 15 (range: 11–51) years. Eight patients (62%) were male. The mean Task Force score was 6 ± 1. Nine of these patients (69%) had an RV thrombus only whereas four patients had biventricular thrombi. All 13 ARVC patients had a severely impaired RV function (RV fractional area change 16 ± 9% and RV ejection fraction 15 ± 4%); LV ejection fraction (LVEF) was 40 ± 15%. ARVC patients with an additional LV thrombus had a lower LVEF than the others (24 ± 11 vs. 47 ± 11, p = 0.02). Under therapeutic anticoagulation, complete thrombus resolution was observed in 9/13 patients (69%).

Conclusion RV thrombus formation is a potential complication of ARVC with impaired RV function. In patients with biventricular involvement, thrombi may also occur within the LV. Anticoagulation is generally effective to dissolve RV thrombi. This study highlights the need for awareness during cardiac imaging to detect this rare complication of ARVC.

Multiple clinical profiles of families with the short QT syndrome

Aims

Short QT syndrome (SQTS) is a rare cardiac channelopathy characterized by a shortened corrected QT (QTc)-interval that can lead to ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate the clinical phenotypes and long-term outcomes of three families harbouring genetic mutations associated with the SQTS.

Methods and results

Clinical data included medical history, physical examination, 12-lead ECG, 24-h Holter-ECG, and transthoracic echocardiography from three index patients and their first-degree relatives. Next generation clinical exome sequencing and genetic cascade screening were performed in index patients and their relatives, respectively. Two index patients experienced malignant ventricular arrhythmias and one patient suffered from arrhythmogenic syncope during a median follow-up period of 8 years. They all had genetic mutations associated with the SQTS. Two mutations were found in the KCNH2 gene, and one in the CACNA2D gene. One patient had an additional SCN10A variant. Alive and mutation-positive family members had short QTc-intervals, but no further phenotypic manifestations. None of the mutation-negative family members had an abnormal ECG or any symptoms. In all patients with shortened QTc-intervals, the QTc-interval had a low long-term variability and QTc shortening always remained detectable by 12-lead ECG.

Conclusion

This study shows the variety of phenotypic manifestations in different families with SQTS. It further emphasizes the importance of a 12-lead ECG for early diagnosis, and the utility of next generation sequencing for the identification of mutations associated with the SQTS.

Hemodynamic Changes in the Right Ventricle Induced by Variations of Cardiac Output: A Possible Mechanism for Arrhythmia Occurrence in the Outflow Tract

The rationale of this paper is to investigate right ventricular (RV) hemodynamics in relation to changes in cardiac output, and in particular to study exercise-induced stresses at the RV outflow tract (RVOT), which is a common site of ventricular arrhythmias in the athlete’s heart. We hypothesize that the thin-walled RVOT is exposed to high wall shear stresses (WSS) during physiological states associated with high cardiac output such as exercise, and therefore, may be particularly prone to substrate formation leading to ventricular tachyarrhythmias. 3D Particle Tracking Velocimetry (3D-PTV), an optical imaging method, has been performed in a novel anatomically accurate compliant silicone right heart model derived from a high resolution MRI heart scan of a healthy male proband. RV and RVOT flow patterns at resting conditions were obtained from two healthy athletic male proband’s hearts and two patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) via phase contrast magnetic resonance imaging (PC-MRI). The healthy case was used as a reference for validating the in vitro flow patterns of the silicone model, while the diseased cases were used to generalize our findings and investigate possible changes in hemodynamic stresses with RV morphological remodelling. Our results showed that both healthy and diseased geometries consistently displayed an increased WSS in the RVOT relative to the rest of the RV. We found that increases in cardiac output may lead to increases of mean kinetic energy (MKE), laminar viscous dissipation and WSS at the RVOT. Furthermore, higher peak WSS magnitudes were found for the diseased cases. The identified high WSS regions may correlate with the common site of RVOT ventricular tachycardia in athletes and patients with ARVC/D. Our results imply that exercise, as well as anatomical and functional remodeling might alter RV wall shear stress both in magnitude and spatial distribution, leading to increased hemodynamic stresses in the RVOT.

Arrhythmogenic right ventricular cardiomyopathy: implications of next-generation sequencing in appropriate diagnosis

Aims

To evaluate potential differences in the genetic profile of cases with 'definite', 'borderline', and 'possible' arrhythmogenic right ventricular cardiomyopathy (ARVC) phenotype by 2010 task force criteria using a custom genetic panel after whole-exome analysis.

Methods and results

We performed whole-exome sequencing in 14 cases with the clinical diagnosis ARVC using an 'Illumina HighSeq 2000' system. We presented our initial results focused on 96 known cardiomyopathy and channelopathy genes. According to the 2010 task force criteria, 7/14 cases (50%) were classified as 'definite' phenotype, 4/14 (29%) were 'borderline', and 3/14 (21%) were diagnosed with the 'possible' phenotype. Nine out of 14 patients (64%) were males, and all were Caucasians, with an average age at genetic diagnosis of 50 ± 15 years. Among the seven cases with the 'definite' phenotype, six (86%) had a putative desmosomal mutation, while none of the seven patients with a 'possible' or borderline task force classification phenotype hosted putative mutations in desmosomal genes. Four (57%) of them had rare variants in other dilated cardiomyopathy (DCM) genes.

Conclusions

Most of the patients with 'definite' ARVC phenotype by task force 2010 host mutations in desmosomal genes. Weaker ARVC phenotypes host variants/mutations in other DCM genes and result in a disease spectrum, including DCM or phenocopies of ARVC.

Feasibility of zero or near zero fluoroscopy during catheter ablation procedures

BACKGROUND

Awareness of risks associated with radiation exposure to patients and medical staff has significantly increased. It has been reported before that the use of advanced three-dimensional electroanatomical mapping (EAM) system significantly reduces fluoroscopy time, however this study aimed for zero or near zero fluoroscopy ablation to assess its feasibility and safety in ablation of atrial fibrillation (AF) and other tachyarrhythmias in a "real world" experience of a single tertiary care center.

METHODS

This was a single-center study where ablation procedures were attempted without fluoroscopy in 34 consecutive patients with different tachyarrhythmias under the support of EAM system. When transseptal puncture (TSP) was needed, it was attempted under the guidance of intracardiac echocardiography (ICE).

RESULTS

Among 34 patients consecutively enrolled in this study, 28 (82.4%) patients were referred for radiofrequency ablation (RFA) of AF, 3 (8.8%) patients for ablation of right ventricular outflow tract (RVOT) ventricular extrasystole (VES), 1 (2.9%) patient for ablation of atrioventricular nodal reentry tachycardia (AVNRT), 2 (5.9%) patients for typical atrial flutter ablation. In 21 (62%) patients the en- tire procedure was carried out without the use of fluoroscopy. Among 28 AF patients, 15 (54%) patients underwent ablation without the use of fluoroscopy and among these 15 patients, 10 (67%) patients required TSP under ICE guidance while 5 (33%) patients the catheters were introduced to left atrium through a patent foramen ovale. In 13 AF patients, fluoroscopy was only required for double TSP. The total procedure time of AF ablation was 130 ± 50 min. All patients referred for atrial flutter, AVNRT, and VES of the RVOT ablation did not require any fluoroscopy.

CONCLUSIONS

This study demonstrates the feasibility of zero or near zero fluoroscopy procedure including TSP with the support of EAM and ICE guidance in a "real world" experience of a single tertiary care center. When fluoroscopy was required, it was limited to TSP hence keeping the radiation dose very low.

Sex hormones affect outcome in arrhythmogenic right ventricular cardiomyopathy/dysplasia: from a stem cell derived cardiomyocyte-based model to clinical biomarkers of disease outcome

Aims

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by fibrofatty infiltration of the myocardium and ventricular arrhythmias that may lead to sudden cardiac death. It has been observed that male patients develop the disease earlier and present with more severe phenotypes as compared to females. Thus, we hypothesized that serum levels of sex hormones may contribute to major arrhythmic cardiovascular events (MACE) in patients with ARVC/D.

Methods and results

The serum levels of five sex hormones, sex hormone-binding globulin, high sensitivity troponin T, pro-brain natriuretic peptide, cholesterol, triglycerides, insulin, and glucose were measured in 54 ARVC/D patients (72% male). Twenty-six patients (48%) experienced MACE. Total and free testosterone levels were significantly increased in males with MACE as compared to males with a favourable outcome, whereas estradiol was significantly lower in females with MACE as compared to females with a favourable outcome. Increased testosterone levels remained independently associated with MACE in males after adjusting for age, body mass index, Task Force criteria, ventricular function, and desmosomal mutation status. Furthermore, an induced pluripotent stem cell-derived ARVC/D cardiomyocyte model was used to investigate the effects of sex hormones. In this model, testosterone worsened and estradiol improved ARVC/D-related pathologies such as cardiomyocyte apoptosis and lipogenesis, strongly supporting our clinical findings.

Conclusions

Elevated serum testosterone levels in males and decreased estradiol levels in females are independently associated with MACE in ARVC/D, and directly influence disease pathology. Therefore, determining the levels of sex hormones may be useful for risk stratification and may open a new window for preventive interventions.

Low QRS Voltage and Atrial Fibrillation Precluding Implantation of a Subcutaneous Implantable Cardioverterdefibrillator in a Patient with Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (AC) is a rare mostly hereditary disease, in which fibro-fatty tissue replaces cardiomyocytes. Typically, the first alterations of the disease can be encountered in the epicardium of the right ventricle in adolescent patients. From there, the disease usually progresses over time. Besides the development of heart failure, the clinical significance of the disease is determined by the predisposition to potentially lethal ventricular arrhythmias. Hence, a majority of patients with AC require an implantable cardioverter-defibrillator (ICD) to be protected from sudden cardiac death. A recently developed alternative to transvenous systems are subcutaneous ICDs (S-ICD), associated with a lower risk of device-related complications such as endocarditis since no foreign material is implanted within the heart and vascular system. In this report, we describe and discuss our experience with the implantation of a S-ICD in a patient with AC, who had low QRS voltage and persistent atrial fibrillation precluding successful S-ICD implantation, as well as the challenges encountered during subsequent transvenous lead implantation.

Investigation of Atrial Vortices Using a Novel Right Heart Model and Possible Implications for Atrial Thrombus Formation

The main aim of this paper is to characterize vortical flow structures in the healthy human right atrium, their impact on wall shear stresses and possible implications for atrial thrombus formation. 3D Particle Tracking Velocimetry is applied to a novel anatomically accurate compliant silicone right heart model to study the phase averaged and fluctuating flow velocity within the right atrium, inferior vena cava and superior vena cava under physiological conditions. We identify the development of two vortex rings in the bulk of the right atrium during the atrial filling phase leading to a rinsing effect at the atrial wall which break down during ventricular filling. We show that the vortex ring formation affects the hemodynamics of the atrial flow by a strong correlation (ρ = 0.7) between the vortical structures and local wall shear stresses. Low wall shear stress regions are associated with absence of the coherent vortical structures which might be potential risk regions for atrial thrombus formation. We discuss possible implications for atrial thrombus formation in different regions of the right atrium.