[Cardiogenetics in Germany- a view and review]. / Kardiogenetik in Deutschland ­ ein (Rück­)Blick.

The development of the cardiogenetics field in Germany has been increasing since the mid-1990s with many national contributions, some of them were really important and groundbreaking. The starting point was and still is the patient and his family, e.g. with a familial form of arrhythmia or cardiomyopathy, the clarification of the genetic cause and the personalized treatment of those being affected. The scientific, always translationally oriented interest in identifying a causative gene and uncovering the underlying pathomechanisms has led to notable contributions for Brugada syndrome, short QT syndrome and cardiac conduction disorders or sinus node dysfunction, but also in DCM or ARVC. What is important, however, is always the way back (bench > bed side): implementation of national and international recommendations for cardiogenetic diagnostics in daily cardiological routine and the personalized care and therapy of those being affected.

Diagnosis and treatment of cardiac amyloidosis: position statement of the German Cardiac Society (DGK).

Systemic forms of amyloidosis affecting the heart are mostly light-chain (AL) and transthyretin (ATTR) amyloidoses. The latter is caused by deposition of misfolded transthyretin, either in wild-type (ATTRwt) or mutant (ATTRv) conformation. For diagnostics, specific serum biomarkers and modern non-invasive imaging techniques, such as cardiovascular magnetic resonance imaging (CMR) and scintigraphic methods, are available today. These imaging techniques do not only complement conventional echocardiography, but also allow for accurate assessment of the extent of cardiac involvement, in addition to diagnosing cardiac amyloidosis. Endomyocardial biopsy still plays a major role in the histopathological diagnosis and subtyping of cardiac amyloidosis. The main objective of the diagnostic algorithm outlined in this position statement is to detect cardiac amyloidosis as reliably and early as possible, to accurately determine its extent, and to reliably identify the underlying subtype of amyloidosis, thereby enabling subsequent targeted treatment.

Sudden unexpected cardiac death and postmortem identification of a novel RYR2 gene mutation.

A 13-year-old female was found lifeless at home. The autopsy and consecutive histological and toxicological examinations showed blood-rich and edematous lungs and foamy bloody content in the airways. No morphologic pathological findings were seen, especially no bleeding sources. Toxicological findings were unremarkable. The specific cause of death remained unclear. Due to reported losses of consciousness, a moleculargenetic postmortem testing was performed. A so far undescribed mutation in the cardiac ryanodine receptor gene RyR2 was detected. This mutation is suitable to explain the case history as well as the morphological findings. The cardiac ryanodine receptor gene RyR2 encodes the ryanodine receptor type 2, an ion channel in the cardiomyocytes. The ion channel regulates the influx of calcium ions and thus influences myocardial activity. Mutations in this channel may result in the catecholaminergic polymorphic ventricular tachycardia (CPVT), a cardiac arrhythmia that can lead to syncope and sudden cardiac death. This case demonstrates the usefulness and need of molecular autopsy, in particular to identify and treat possibly affected family members.

Biventricular myocardial strain analysis using cardiac magnetic resonance feature tracking (CMR-FT) in patients with distinct types of right ventricular diseases comparing arrhythmogenic right ventricular cardiomyopathy (ARVC), right ventricular outflow-tract tachycardia (RVOT-VT), and Brugada syndrome (BrS).

OBJECTIVES: As underlying heart diseases of right ventricular tachyarrhythmias, ARVC causes wall-motion abnormalities based on fibrofatty myocardial degeneration, while RVOT-VT and BrS are thought to lack phenotypic MR characteristics. To examine whether cardiac magnetic resonance (CMR) feature tracking (FT) in addition to ARVC objectively facilitates detection of myocardial functional impairments in RVOT-VT and BrS. METHODS: Cine MR datasets of four retrospectively enrolled, age-matched study groups [n = 65; 16 ARVC, 26 RVOT-VT, 9 BrS, 14 healthy volunteers (HV)] were independently assessed by two distinctly experienced investigators regarding myocardial function using CMR-FT. Global strain (%) and strainrate (s-1) in radial and longitudinal orientation were assessed at RVOT as well as for left (LV) and right (RV) ventricle at a basal, medial and apical section with the addition of a biventricular circumferential orientation. RESULTS: RV longitudinal and radial basal strain (%) in ARVC (- 12.9 ± 4.2; 11.4 ± 5.1) were significantly impaired compared to RVOT-VT (- 18.0 ± 2.5, p ≤ 0.005; 16.4 ± 5.2, p ≤ 0.05). Synergistically, RVOT endocardial radial strain (%) in ARVC (33.8 ± 22.7) was significantly lower (p ≤ 0.05) than in RVOT-VT (54.3 ± 14.5). For differentiation against BrS, RV basal and medial radial strain values (%) (13.3 ± 6.1; 11.8 ± 2.9) were significantly reduced when compared to HV (21.0 ± 6.9, p ≤ 0.05; 20.1 ± 6.6, p ≤ 0.005), even in case of a normal RV ejection fraction (EF) (> 45%; n = 6) (12.0 ± 2.7 vs. 20.1 ± 6.6, p ≤ 0.05). CONCLUSIONS: CMR-FT facilitates relevant differentiation in patients with right ventricular tachyarrhythmias: between ARVC against RVOT-VT and HV as well as between BrS with even a preserved EF against HV.

[Genetic testing to prevent sudden cardiac death]. / Genetische Diagnostik zur Vermeidung des plötzlichen Herztods.

Successfully incorporating genetic testing into clinical practice to prevent sudden cardiac death (SCD) requires (1) appropriate recognition of an inherited cardiovascular condition, (2) identification of appropriate family members at risk and for genetic testing, (3) selection of the appropriate genetic test and information about the expected diagnostic yield, (4) understanding the complexity of result interpretation and distinct handling of incidental findings and (5) providing effective communication and medical advice regarding the genetic and medical results and implications to the patient and his family. Molecular autopsy in SCD victims will be of future importance to determine the cause of death. Interdisciplinary patient care should be provided in specialized centers with a high level of cardiogenetic expertise and is recommended to provide precise and individualized patient management.

Molecular genetic diagnostics for ventricular arrhythmias and sudden cardiac death syndromes.

Inherited forms of ventricular arrhythmias are rare diseases, but a major cause for severe cardiac events, sudden unexplained death syndromes, and death in young adults, infants, and children. Each disorder is genetically heterogeneous (5-20 genes per disease) and molecular testing may include both core genes and less common disease genes as well. Owing to the rapid development and feasibility of sequencing technologies enabling a parallel analysis of several hundred genes up to a whole exome, disease mutations can be identified very efficiently, but have to be seen in the complexity and natural variance of the human genome. Precise phenotypic knowledge and advanced gene variant interpretation are important to ensure adequate patient diagnostics and management. This article focuses on the genetic causes of inherited arrhythmia forms predisposing patients to sudden cardiac death and discusses practical issues and skills for molecular testing.

Pharmacological targeting in inherited arrhythmia syndromes.

The development of pharmacologic agents for the treatment of diseases is still challenging, especially in rare inherited arrhythmia syndromes like long and short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia. The underling pathophysiologic mechanism of these inherited diseases is in most cases either a gain- or a loss-of-function due to mutations in ion channel genes. Although the biophysical properties of mutant channel subunits are well studied, little is known about the targeting effect of specific pharmacologic agents. In this review, we focus on the therapeutic (in vivo) and the experimental (in vitro) approaches in the most common inherited forms.

[Catecholaminergic polymorphic ventricular tachycardia]. / Katecholaminerge polymorphe ventrikuläre Tachykardien.

Catecholaminergic polymorphic ventricular tachycardia (PCVT) is a rare, congenital ventricular tachyarrhythmia which occurs in the setting of adrenergic activation. It potentially leads to syncope and/or sudden cardiac death (SCD). PCVT represents one of the most dangerous congenital ion channel diseases. Mutations of the ryanodine receptor gene (RYR2), the calsequestrin gene (CASQ2), and the triadin gene (TRDN) have been identified as an underlying correlate. ß-Blockers are employed as therapy and are sometimes combined with class IC antiarrhythmic drugs, or calcium antagonists of the verapamil type. ICD implantation is recommended in case of persisting syncope in the presence of ß-blocker therapy or survived SCD. Left thoracic sympathectomy represents a subsidiary interventional therapy for individual cases. In addition, modifications of the patient's lifestyle including avoidance of physical stress and heart rates> 120/min are recommended.

Arrhythmogenic right ventricular cardiomyopathy: an update on pathophysiology, genetics, diagnosis, and risk stratification.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy accounting for life-threatening ventricular tachyarrhythmias and sudden death in young individuals and athletes. Over the past years, mutations in desmosomal genes have been identified as disease-causative. However, genetic heterogeneity and variable phenotypic expression alongside with diverse disease progression still render the evaluation of its prognostic implication difficult. ARVC was initially entered into the canon of cardiomyopathies of the World Health Organization in 1995, and international efforts have resulted in the 2010 modified diagnostic criteria for ARVC. Despite all additional insights into pathophysiology, clinical management, and modern risk stratification, under-/misdiagnosing of ARVC remains a problem and hampers reliable statements on the incidence, prevalence, and natural course of the disease.This review provides a comprehensive overview of the current literature on the pathogenesis, diagnosis, treatment, and prognosis of ARVC and sheds some light on potential new developments in these areas.

[Totally subcutaneous cardioverter-defibrillator (S-ICD®) : recent experience and future perspectives]. / Komplett subkutaner Kardioverter-Defibrillator (S-ICD®) : Aktuelle Erfahrungen und Ausblick.

The implantable cardioverter defibrillator (ICD) is an established therapy for patients at risk of sudden cardiac death. Nevertheless the endocardial electrode in conventional systems plays a major role in long-term complications (difficult removal, risk of endocarditis, etc.). The totally subcutaneous ICD (S-ICD®, Cameron Health, San Clemente, CA, USA) represents a new and particularly significant development in ICD therapy which, since it requires no electrode in or on the heart, results in significantly fewer perioperative and long-term complications (e.g., thromboembolism and endocarditis risk). Although we see an indication for primary and secondary prevention, patients need to be informed about the limited data from randomized trials with the S-ICD®. As there is no permanent pacing option, patients in whom a pacemaker is indicated are not appropriate candidates for S-ICD®. In addition, patients with ventricular tachycardias that can be terminated by antitachycardic pacing are not recommended for the device. In the present article, we report our initial experience with the 18 patients implanted with the S-ICD® to date, comment on the available studies and offer a critical perspective.

Brugada-like cardiac disease in myotonic dystrophy type 2: report of two unrelated patients.

BACKGROUND: Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystem disorder caused by CCTG repeat expansions within intron 1 of the ZNF9 gene on chromosome 3q. Cardiac conduction disturbances, supraventricular arrhythmias, and cardiomyopathy are described in DM2 but Brugada-like features have not yet been reported. Brugada syndrome (BS) is a genetically heterogeneous cardiac conduction disorder which is characterized by a significant ST-segment elevation upon ECG evaluations and bears an increased risk for sudden cardiac death. CASE REPORTS: We report two unrelated patients with genetically confirmed DM2 who developed clinical relevant cardiac arrhythmias with syncopal events from 35 (patient 1) and 47 years (patient 2). Brugada-like ECG findings were present in both patients. Family history was negative for BS, but the mothers of both index patients were also affected by DM2 and had different ventricular rhythm disturbances. SCN5A gene sequencing revealed an unknown genetic variant c.4140 C > A, p.N1380K, in patient 1, while no mutation was detected in patient 2. DISCUSSION: Our observations may suggest that Brugada-like cardiac arrhythmias can occur in DM2, as this seems also to be the case in DM1. The chance association of two independent inherited disorders has to be considered and cannot be excluded in one of our patients. However, on statistical grounds, this possibility cannot explain all observed cases of DM with Brugada-like cardiac disease.

Mutational spectrum in the cardiac transcription factor gene NKX2.5 (CSX) associated with congenital heart disease.

Heterozygous mutations in the human transcription factor gene NKX2.5 are associated with either isolated or combined congenital heart disease (CHD), primarily secundum atrial septal defect-II (ASD-II), ventricular septal defect (VSD) or tetralogy of Fallot (TOF). Thus, NKX2.5 has an important role at different stages of cardiac development. The frequency of NKX2.5 mutations in a broader phenotypic spectrum of CHD is not completely determined. Here, we report the identification of two novel mutations in the NKX2.5 gene in a screening of 121 patients with a broad spectrum of CHDs. However, mutations were only associated with familial ASD-II and in both, patients also showed atrioventricular (AV) block. We found one missense mutation (R190L) in two siblings with ASD-II and a frame-shift mutation (A255fsX38) at the C-terminus in a mother and daughter. In addition, a single patient with hypoplastic left heart syndrome (HLHS) had the reported sequence variant R25C. Importantly, sporadic cases of CHD that share phenotypic aspects of NKX2.5 mutation carriers were negative for genetic analysis. Thus, even important for cardiac development, germline mutations in NKX2.5 are rare in patients with sporadic CHD and genetic and/or pathophysiologic heterogeneity is likely for sporadic forms of CHD.

Long-term prognosis of patients diagnosed with Brugada syndrome: Results from the FINGER Brugada Syndrome Registry.

BACKGROUND: Brugada syndrome is characterized by ST-segment elevation in the right precordial leads and an increased risk of sudden cardiac death (SCD). Fundamental questions remain on the best strategy for assessing the real disease-associated arrhythmic risk, especially in asymptomatic patients. The aim of the present study was to evaluate the prognosis and risk factors of SCD in Brugada syndrome patients in the FINGER (France, Italy, Netherlands, Germany) Brugada syndrome registry. METHODS AND RESULTS: Patients were recruited in 11 tertiary centers in 4 European countries. Inclusion criteria consisted of a type 1 ECG present either at baseline or after drug challenge, after exclusion of diseases that mimic Brugada syndrome. The registry included 1029 consecutive individuals (745 men; 72%) with a median age of 45 (35 to 55) years. Diagnosis was based on (1) aborted SCD (6%); (2) syncope, otherwise unexplained (30%); and (3) asymptomatic patients (64%). During a median follow-up of 31.9 (14 to 54.4) months, 51 cardiac events (5%) occurred (44 patients experienced appropriate implantable cardioverter-defibrillator shocks, and 7 died suddenly). The cardiac event rate per year was 7.7% in patients with aborted SCD, 1.9% in patients with syncope, and 0.5% in asymptomatic patients. Symptoms and spontaneous type 1 ECG were predictors of arrhythmic events, whereas gender, familial history of SCD, inducibility of ventricular tachyarrhythmias during electrophysiological study, and the presence of an SCN5A mutation were not predictive of arrhythmic events. CONCLUSIONS: In the largest series of Brugada syndrome patients thus far, event rates in asymptomatic patients were low. Inducibility of ventricular tachyarrhythmia and family history of SCD were not predictors of cardiac events.

QT interval prolongation and risk for cardiac events in genotyped LQTS-index children.

Congenital long-QT syndrome (LQTS) is an inherited cardiac disorder with a disturbance in repolarization characterized by a prolonged QT interval on the surface electrocardiogram and life-threatening ventricular tachycardia. Publications from the International LQTS Registry have provided information that the cardiac risk may be influenced by gender, genotype, exposure to arrhythmia triggers, and previous cardiac events. In children, early-onset of disease, changes in life style, and medical treatment is a sensitive issue and significant, gender-related differences of a first life-threatening event were reported. Thus, we investigated the clinical features of a large genotyped population of LQTS-index children (age < or =16 years) upon a single-center experience and determined risk factors for symptoms. Of 83 children [mean corrected QT interval (QTc) 510 +/- 74 ms], 89% had LQT1, -2, or -3. Nine patients (11%) were identified as having Jervell and Lange-Nielsen syndrome. Among symptomatic children (n = 51, 61%), syncope was the most prevalent symptom at initial presentation (49%); however, aborted cardiac arrest (ACA) occurred in 33% and sudden cardiac death (SCD) in 18%, respectively, as the initial manifestation. During a mean follow-up period of 5.9 +/- 4.7 years, 31% of the children developed symptoms while on therapy (86% syncope, 9% ACA, 5% SCD). Statistical analyses of risk factors for cardiac events showed that the QTc >500 ms was a strong and significant predictor for cardiac events during follow-up (p = 0.02). Furthermore, a prior syncope [hazard ratio (HR), 4.05; 95% confidence interval (CI), 1.1 to 15.0; p = 0.03] or an ACA (HR, 11.7; 95% CI, 3.1 to 43.4; p = <0.001) identified children with an increased risk for recurrent cardiac events compared to asymptomatic LQT children. LQTS-index children manifest with a high percentage of severe symptoms. Among presently validated risk factors for LQTS, a QTc interval >500 ms and a history of prior syncope or ACA were strong predictors for recurrent cardiac events.

Polymorphisms in the cardiac sodium channel promoter displaying variant in vitro expression activity.

Variable transcription of the cardiac sodium channel gene is a candidate mechanism determining arrhythmia susceptibility. We have previously cloned and characterized the core promoter and flanking region of SCN5A, encoding the cardiac sodium channel. Loss-of-function mutations in this gene have been reported in approximately 20% of patients with Brugada syndrome, an inherited cardiac electrical disorder associated with a high incidence of life-threatening arrhythmias. In this study, we identified DNA variants in the proximal 2.8 kb promoter region of SCN5A and determined their frequency in 1,121 subjects. This population consisted of 88 Brugada syndrome patients with no SCN5A coding region mutation, and 1,033 anonymized subjects from various ethnicities. Variant promoter activity was assayed in CHO cells and neonatal cardiomyocytes by transient transfection of promoter-reporter constructs. Single-nucleotide polymorphisms (SNPs) were identified at approximately 1/200 base pairs which are: 11 in the 5'-flanking region, 1 in exon 1, and 5 in intron 1. In addition, a haplotype consisting of two SNPs in complete linkage disequilibrium was identified. Minor allele frequencies were >5% in at least one ethnic panel at 5/19 polymorphic sites. In vitro functional analysis in cardiomyocytes identified four variants with significantly (P<0.05) reduced reporter activity (up to 63% reduction). The largest changes were seen with c.-225-1790 G>A, which reduced reporter activity by 62.8% in CHO cells and 55% in cardiomyocytes. From these results, we can conclude that the SCN5A core promoter includes multiple DNA polymorphisms with altered in vitro activity, further supporting the concept of interindividual variability in transcription of this cardiac ion channel gene.

[Long QT syndrome causing grand mal epilepsy: case report, pedigree, therapeutic options, and review of the literature]. / Long-QT-Syndrom als Differenzialdiagnose einer Grand-Mal-Epilepsie: Fallbericht, Stammbaum, Therapieoptionen und Literaturübersicht.

A 24-year-old female with a history of epileptic seizures was admitted after prolonged cardiac resuscitation. The clinical course together with additional examinations led to the diagnosis of severe hypoxic cerebral damage, with poor prognosis for neurological outcome. In her initial ECG, as in the ECGs of several family members, QT prolongation was diagnosed. Meticulous history taking and ensuing genetic analysis led to the diagnosis of familial long QT syndrome (LQTS) with a mutation in the LQT-2 gene (HERG). In retrospect, the previous seizure episodes have to be considered cardiac syncopes. Two family members had previously died suddenly, and ECG and genetic analysis revealed that a total of eight family members were affected. These relatives were prophylactically treated with beta blockers or supplied with automated implantable cardioverter defibrillating devices. The literature concerning LQTS, diagnosis and prognosis of cerebral hypoxic damage, and differentiation between seizures and cardiac syncopes is discussed.

[Right ventricular tachyarrhythmias--diagnostics and therapy]. / Rechtsventrikuläre Tachyarrhythmien--Diagnostik und Therapie.

Ventricular tachyarrhythmias originating from the right ventricle frequently occur in young, apparently healthy patients with rare underlying cardiac diseases. Among these are arrhythmogenic right ventricular cardiomyopathy (ARVC), idiopathic right ventricular outflow-tract tachycardia (RVOVT), and Brugada syndrome (BrS). All harbor the risk of sudden cardiac death, whereas they differ substantially as to diagnosis, therapy and prognosis. This is the reason why detailed investigations are an essential prerequisite for further efficient individualized management strategies which are mainly directed to prevent sudden cardiac death and to minimize the risk of arrhythmia recurrences in affected patients, respectively. Both antiarrhythmic drug therapy, catheter ablation, and the implantation of an automatic cardioverter defibrillator may, therefore, be a first-line therapeutic option in tailored treatment regimens. This review is a summary of the available literature on pathogenesis, diagnosis, treatment, and prognosis of such diseases associated with right ventricular tachyarrhythmias.

[Atrial flutter after orthotopic heart transplantation due to recipient-to-donor transatrial conduction]. / Vorhofflattern in der Frühphase nach orthotoper Herztransplantation.

A few weeks after orthotopic heart transplantation, a male adolescent developed atrial arrhythmias of the donor heart due to an atypical recipient atrial flutter with a recipient-to-donor transatrial conduction resulting in an absolute arrhythmia. Under medication with propafenone, the atrial flutter of the donor heart could be terminated with cardioversion.

Long QT syndrome. Why does sex matter?

There is increased awareness of the extent to which cardiac function is influenced by gender. One of the most dramatic and potentially lethal differences is that seen in cardiac repolarization reflected in the QT interval of the surface ECG. Gender differences in QT and QTc intervals have been observed to change during the lifetime in the general population. These differences can be explained to a large extent by sex hormone driven differences in gene expression of myocardial ion channels. Numerous studies have shown that women's risk to suffer arrhythmias in the context of QT prolonging drugs is doubled compared to men. For familial long QT syndrome there is no conclusive evidence for gender effects with respect to disease onset or mortality. Only subgroup analysis by genotype demonstrated a higher risk in female patients carrying mutations in the LQT2 locus. Special attention should be given to drug-induced QT prolongation in women.