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

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

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.

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.

Predictors of adverse outcome in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy: long term experience of a tertiary care centre

OBJECTIVE

To investigate the predictors for adverse clinical outcome in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) during long term follow up.

METHODS

61 patients with ARVD/C were studied to assess the impact of family history, clinical findings, surface ECG parameters, echocardiographic findings, and electrophysiological findings on clinical outcome. The prevalence of these risk factors were compared in two patient groups: group A (patients with adverse clinical outcome: sudden cardiac death, death from heart failure, or heart transplant) and group B (survivors excluding patients who received a heart transplant).

RESULTS

Mean age at first diagnosis was 44 (14) years. The mean follow up duration was 55 (47) months. Ten patients (16%) died during follow up. The cause of death of eight of these patients was probably arrhythmic. Two patients died of advanced heart failure. Five patients underwent heart transplantation because of terminal heart failure. Risk factors significantly associated with adverse outcome were history of congestive heart failure (p < 0.001), the presence of left ventricular involvement on echocardiography (p < 0.001), left atrial dilatation (p < 0.05), prolonged PR duration (p < 0.01), prolonged QRS in V1 (p < 0.05), and bundle branch block (p < 0.05). In multivariate analysis, history of congestive heart failure and presence of left ventricular involvement were identified as independent risk predictors for an adverse outcome.

CONCLUSIONS

Congestive heart failure and left ventricular involvement are independently associated with adverse outcome in patients with ARVD/C during long term follow up.

[Ventricular tachycardia--etiology, mechanisms and therapy]

Prevention and therapy of cardiovascular diseases have undergone enormous changes over the last decades. However, ventricular tachycardias (VT) still pose a major problem in a number of cardiac patients. Analysis of the etiology and mechanism of the tachycardia is of paramount importance for initiation of specific therapies. The morphology of VTs on the surface ECG can be either polymorphic or monomorphic. Polymorphic VTs have a constantly changing QRS-morphology due to the variable ventricular activation, without specific origin. This kind of VT is mainly caused by an acute, often reversible condition, such as ischemia or QT-prolongation. These VTs are potentially malignant, they cannot be treated by catheter ablation. In contrast, monomorphic VTs have a constant QRS-morphology, indicative of repetitive ventricular depolarisation in the same activation sequence. This kind of VT is either caused by focal abnormal activity (triggered activity, automaticity, micro-reentry) or by an arrhythmogenic substrate (macro-reentry). Focal idiopathic VTs usually have a benign prognosis and catheter ablation is potentially curative. The majority of ventricular arrhythmias, however, are substrate-related reentry tachycardias, most commonly based on an infarct scar Therapy of first choice for these patients is the treatment with an implantable Cardioverter/Defibrillator (ICD). Catheter ablation is indicated in case of drug refractory recurrent VTs triggering repeated ICD therapies. The different therapeutic strategies are not alternative but complementary options in many patients.

ICD-Therapie bei Patienten mit koronarer Herzkrankheit – Inzidenz adäquater Interventionen

Hintergrund: Implantierbare Cardioverter/Defibrillatoren (ICD) stellen eine etablierte Therapieform für Risikopatienten hinsichtlich maligner ventrikulärer Arrhythmien dar. Der Überlebensvorteil der ICD- Therapie bei Patienten mit koronarer Herzkrankheit und ventrikulären Tachykardien gegenüber einer antiarrhythmischen Therapie ist erwiesen. Auch in der Primärprävention setzt sich bei Hochrisikopatienten zunehmend die ICD-Therapie durch. Wir berichten über die Inzidenz adäquater ICD-Therapien bei Patienten mit koronarer Herzkrankheit, bei denen im UniversitätsSpital Zürich ein ICD implantiert wurde. Methoden: 104 konsekutive Patienten (97 Männer, 7 Frauen, mittleres Alter 67 ± 10 Jahre) mit koronarer Herzkrankheit, bei denen nach AHA/ACC/NASPE Richtlinien eine Indikation zur ICD-Implantation gestellt wurde und im UniversitätsSpital Zürich im Zeitraum von Januar 2000 bis Juli 2003 erstmals mit einem ICD versorgt wurden, sind in die Studie eingeschlossen. Eine Nachkontrolle erfolgte alle drei bis sechs Monate, wobei alle ICD-Therapien dokumentiert wurden. Diese Dokumentationen wurden zur Analyse adäquater und nicht-adäquater ICD-Therapien verwendet. Resultate: Der Nachbeobachtungszeitraum dauerte 383 ± 195 Tage. Die Zeit bis zur ersten adäquaten Therapie betrug 201 ± 283 Tage. Die kumulative Inzidenz für die erste adäquate Therapieabgabe betrug nach sechs Monaten 21%, nach zwei Jahren 39% und nach vier Jahren 59%. Bei 64% der Patienten, die eine ICD-Therapie erfuhren, wurde primär eine ATP-Therapie, bei 36% primär eine Schock-Therapie abgegeben. ATP war in 83% der Fälle erfolgreich. Im Nachbeobachtungszeitraum sind zwölf Patienten verstorben. Schlussfolgerung: In unserer Studie zeigte sich der Nutzen der ICD-Therapie bei Risikopatienten mit koronarer Herzkrankheit nach einem relativ kurzen Zeitraum und bestätigt damit den Stellenwert der ICD-Therapie bei der primären und sekundären Prävention.

Psychopharmaka und Herzrhythmusstörungen

Psychopharmaka verschiedener Stoffklassen werden seit vier Jahrzehnten mit Herzrhythmusstörungen assoziiert. Bis in die frühen 90er Jahre beschränkte sich das Problem scheinbar auf Intoxikationen oder auf Patienten mit vorbestehenden Herzerkrankungen. In den letzten zehn Jahren hat sich jedoch gezeigt, dass auch normal dosierte, nicht-kardiale Medikamente bei gesunden Personen unter bestimmten Umständen lebensbedrohliche Rhythmusstörungen auslösen können. Die Gemeinsamkeit dieser Medikamente ist die Eigenschaft, das QT-Intervall zu verlängern. Unter den Neuroleptika ist das niedrig potente Phenothiazin Thioridazin (Melleril) dafür am besten belegt. Auch von hochpotenten Neuroleptika existieren einige Berichte über proarrhythmische Eigenschaften. Während eine QT-Verlängerung auch bei neuen, atypischen Neuroleptika beschrieben wurde, sind Torsade de pointes und plötzliche Todesfälle bisher nur in Einzelfällen beschrieben worden. Medikamente mit Klasse I antiarrhythmischer Wirkung sind nach Myokardinfarkt potenziell gefährlich, und damit sollten trizyklische Antidepressiva mit ihrer Klasse I Wirkung bei ischämischer Herzkrankheit vermieden werden. Selektive Serotonin Re-uptake Inhibitoren können aufgrund bisher verfügbarer Daten bei dieser Patientengruppe als sicher bezeichnet werden. Bei Patienten mit vorbestehender QT-Verlängerung oder bei Patienten nach Torsade de pointes unter anderer Medikation sind Substanzen mit QT-verlängernder Wirkung zu vermeiden. Wechselwirkungen mit andern Medikamenten können sehr bedeutsam sein. Lithium ist bekannt für seine Sinusknoten- und Reizleitungsstörungen.

[Catheteer ablation technique of atrial fibrillation]

Atrial fibrillation is the most frequent arrhythmia with a prevalence of 1.7% in the general population and 5% in the population over 65 year old [1], the prevalence in men over 65 years is even 9.1% [2]. Atrial fibrillation is divided dependent on its frequency in intermittent, persisting and chronic. The symptoms and the clinical course are individually very different. Responsible for the initiation of atrial fibrillation are triggers, which initiate atrial fibrillation, and a substrate, that means an atrial myocardium altered by remodelling, which maintains atrial fibrillation. A curative treatment was not available until recently. Different ablation techniques were developed: Linear, focal ablation techniques and the isolation of pulmonary veins. The observation that atrial fibrillation will maintain only in large atria, led to the linear ablation techniques with the goal of reducing the atria functionally. The linear ablations have however a small value because of low success rates and high complication rates. Arrhythmogenic foci are of crucial importance in the initiation of atrial fibrillation, these foci are mostly located in the pulmonary veins. This observation led to the focal ablation in the pulmonary veins, which was left again because of the limitations, however. For some years the isolation of pulmonary veins is performed at some large centers. This paper summarizes the most important techniques, success rates and complications of the pulmonary vein isolation. The present indication and the preinterventional diagnostics are discussed. Due to the constantly improving success rates and decreasing complication rates (pulmonary vein stenosis, thrombembolie, cardiac tamponades, mortality practically) the pulmonary vein isolation is an alternative possibility of treatment which can be considered for a subgroup of patients with drug-resistant, symptomatic atrial fibrillation.

[Radiofrequency catheter ablation of ventricular tachycardias]

Management of patients with ventricular tachycardia (VT) is often difficult. Drug therapy is often ineffective. Implantable cardioverter defibrillators (ICDs) can terminate VT episodes but do not prevent them. Radiofrequency (RF) catheter ablation can suppress arrhythmias in selected patients. However, the procedure is often challenging and success rates lower than for ablation of supraventricular tachycardias. The mapping and ablation approach depends on the VT mechanism. Monomorphic VT in patients without structural heart disease is referred to as idiopathic and has a focal origin. These VTs can be abolished by ablation in most of the patients. In VT due to reentry within an area of scar from an old myocardial infarction or cardiomyopathic process, critical parts of the circuit may be difficult to localize, rendering RF ablation challenging. In patients with monomorphic VT, prevention of VT recurrence can be achieved in 55% to 80% of patients. Multiple morphologies of VTs and circuits that are located deep in the endocardium are common problems that reduce efficacy. Furthermore, mapping to identify target regions for ablation can be more difficult if VT is rapid and not tolerated, or not inducible. Recently, multisite mapping of the arrhythmia substrate during sinus rhythm or multisite activation mapping of a few VT beats were shown to be effective for ablation of these "unmappable VTs". Bundle branch reentry tachycardia occur in patients with nonischemic cardiomyopathies, mostly valvular heart disease and can be successfully abolished with RF ablation of the right bundle. However, some of these patients may develop recurrences due to other types of VT. Recent technical developments have increased efficacy and simplified the approach of RF ablation of VT in patients with structural heart disease. However, long-term efficacy is not accurately predictable and implantation of an ICD is mandatory in most of the patients with severely depressed left ventricular function.

[Ventricular tachycardia]

In patients with ventricular tachycardias, various structural and functional conditions can be influenced by certain triggers, initiating the mechanism of the arrhythmia. Thorough understanding of these different factors is paramount for the appropriate choice of treatment. Several options are available for the management of ventricular tachycardias: antiarrhythmic drugs, ICD implantation and catheter ablation or a combination of the above. The prognosis of an individual patient is determined by the underlying disease, the mechanism of tachycardia and the selected therapy. The complexity of several conditions requires a specialized diagnostic approach and tailored medical management. Therefore the patients with the following diagnoses should be referred to a specialized electrophysiology center: survivors of sudden cardiac death old infarct scar, reduced ejection fraction and complex ectopy Cardiomyopathy with syncope or ventricular tachycardias Long QT-Syndrome Brugada Syndrome Right Ventricular Dysplasia recurrent syncopes of unclear etiology.

Role of transmitral blood flow velocity by Doppler echocardiography in the evaluation of coronary artery disease

To determine the relation between presence and severity of coronary artery disease and diastolic filling abnormalities by Doppler echocardiography, recordings of transmitral inflow velocity were made at rest in 90 patients with coronary artery disease and 28 normals. At the time of the Doppler examination, 81 patients with coronary artery disease (90%) and 10 normals (36%) were treated with antianginal medications. No difference was found in the ratio between early (E) and late (A) diastolic filling velocity (E/A ratio) when comparing patients with greater than 70% obstruction of at least one coronary artery to age-matched normals, regardless of the presence or absence of wall motion abnormalities. The E/A ratio was 1.3 +/- 0.46 in coronary patients with normal wall motion, 1.2 +/- 0.47 in coronary patients with abnormal wall motion, and 1.3 +/- 0.53 in both samples of age-matched normals. Multivariate analysis of the relation between E/A ratio and other variables showed that heart rate (F = 24.46, p less than 0.00001) and age (F = 19.51, p less than 0.00001) were significant independent determinants of the E/A ratio, while the presence or severity of coronary artery disease, the presence of hypertension, the magnitude of wall motion abnormalities, and end-diastolic dimension by echocardiography were not. These data suggest that transmitral inflow velocity recordings by Doppler have limited value for the recognition of coronary artery disease, since the E/A ratio is profoundly influenced by other factors, such as heart rate and age.