Electroanatomical voltage mapping with contact force sensing for diagnosis of arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Three-dimensional electroanatomical mapping (EAM) can be helpful to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC). Yet, previous studies utilizing EAM have not systematically used contact-force sensing catheters (CFSC) to characterize the substrate in ARVC, which is the current gold standard to assure adequate tissue contact. OBJECTIVE: To investigate reference values for endocardial right ventricular (RV) EAM as well as substrate characterization in patients with ARVC by using CFSC. METHODS: Endocardial RV EAM during sinus rhythm was performed with CFSC in 12 patients with definite ARVC and 5 matched controls without structural heart disease. A subanalysis for the RV outflow tract (RVOT), septum, free-wall, subtricuspid region, and apex was performed. Endocardial bipolar and unipolar voltage amplitudes (BVA, UVA), signal characteristics and duration as well as the impact of catheter orientation on endocardial signals were also investigated. RESULTS: ARVC patients showed lower BVA vs. controls (p = 0.018), particularly in the subtricuspid region (1.4, IQR:0.5-3.1 vs. 3.8, IQR:2.5-5 mV, p = 0.037) and RV apex (2.5, IQR:1.5-4 vs. 4.3,IQR:2.9-6.1 mV, p = 0.019). BVA in all RV regions yielded a high sensitivity and specificity for ARVC diagnosis (AUC 59-78%, p < 0.05 for all), with the highest performance for the subtricuspid region (AUC 78%, 95% CI:0.75-0.81, p < 0.001, negative predictive value 100%). A positive correlation between BVA and an orthogonal catheter orientation (46°-90°:r = 0.106, p < 0.001), and a negative correlation between BVA and EGM duration (r = -0.370, p < 0.001) was found. CONCLUSIONS: EAM using CFSC validates previous bipolar cut-off values for normal endocardial RV voltage amplitudes. RV voltages are generally lower in ARVC as compared to controls, with the subtricuspid area being commonly affected and having the highest discriminatory power to differentiate between ARVC and healthy controls. Therefore, EAM using CFSC constitutes a promising tool for diagnosis 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.

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.

[Diagnostic yield of the implantable loop recorder to detect the mechanism of syncope--a single center long term experience of a tertiary care center]. / Synkopenabklärung mittels implantierbarem Loop Recorder--Langzeiterfahrung eines Zentrumspitals.

AIM: The aim of this study was to investigate the usefulness in providing diagnostic information about syncope by implantation of a loop recorder (ILR). METHODS AND RESULTS: The study population consisted of 48 consecutive patients (23 male, 25 female, mean age 42 +/- 17) with unexplained syncope who presented between 1998 and 2002 and underwent extensive cardiological screening and were followed with an implantable loop recorder (Reveal or Reveal Plus). The mean follow-up duration was 9 +/- 6 months. During this follow-up in 17 (35%) patients syncope recurred. Arrhythmia correlating with syncope was documented in 15 (88%) of these patients, in 2 (12%) patients an arrhythmia could be excluded. Of these 15 patients with arrhythmogenic cause of syncope 5 (33%) patients revealed higher degree AV-Block, 7 (47%) patients sinus bradycardia or sinus pauses, 4 (27%) due to sick sinus syndrome and 3 (20%) due to neurally mediated syncope, 3 (20%) patients had atrial tachycardias or atrial fibrillation with rapid AV-conduction. As a result of ILR findings 12 pacemakers were implanted and 2 radiofrequency ablations were performed. CONCLUSION: The ILR is a valuable and effective tool to establish an arrhythmic cause for unexplained syncope. In these cases they have an impact on subsequent clinical decision making. ILR can also be useful in ruling out arrhythmias as cause of syncope and presyncope.

[Atrila fibrillation: a review]. / Vorhofflimmern: Eine Ubersicht.

Atrial fibrillation (AF) is the most common sustained arrhythmia and increases exponentially with age. The physiologic basis are certain triggers initiating multiple micro-reentry circuits, which require a certain amount of "myocardial mass" to be sustained. There are numerous predisposing factors for AF, mostly leading to dilatation or hypertrophy of the atrial myocardium. Lone AF, however, occurs in structurally normal hearts. In the management of AF it is mandatory to decide between medical or electrical cardioversion in persistent AF and rate control in permanent AF. Medical cardioversion or prophylaxis of recurrence can be performed with Class IA, IC or Class III antiarrhythmic drugs. The choice of drugs depends on the underlying cardiac pathology of the individual patient. Patients with long duration of poor rate control during AF are at risk for tachycardia-induced cardiomyopathy. Cardioversion is safe to be performed within 48 hours after the onset of AF without prior and--if there is no risk of recurrence--without consecutive anticoagulation. When AF persists longer than 48 hours, anticoagulation for three weeks is mandatory prior to attempted cardioversion, or alternatively, transesophageal echocardiography can be performed to exclude the presence of an intraatrial thrombus. Anticoagulation has to be maintained for a minimum of four weeks after the restoration of sinus rhythm. Anticoagulation is required for paroxysmal, persistent and permanent AF. Lone atrial fibrillation in patients under the age of 60 years is an exception to these rules and does not require anticoagulation. In case of refractory AF with poor rate control, catheter ablation of the AV node with pacemaker implantation is the treatment of last choice. Early attempts to provide a cure for AF included the surgical "Maze" procedure, followed by linear catheter ablation with the goal of reducing the atrial mass. Catheter ablation of the triggers of AF, which mainly originate at the pulmonary veins and the "substrate modification" have been introduced in the last couple of years and is performed increasingly in specialized EP centers.

[ICD therapy in patients with coronary artery disease--incidence of adequate interventions]. / ICD-therapie bei Patienten mit koronarer Herzkrankheit--Inzidenz adäquater Interventionen.

BACKGROUND: The Implantable Cardioverter/Defibrillator (ICD) represents the therapy of choice for patients at risk of malignant ventricular arrhythmias. The survival benefit of the ICD vs antiarrhythmic therapy in patients with coronary artery disease and ventricular tachycardia has been proven. Recently, the ICD therapy has also been established for primary prevention in high risk patients. We report about the incidence of adequate ICD therapies in patients with coronary artery disease, who underwent ICD implantation at the University Hospital Zurich. METHODS: 104 consecutive patients (97 men, 7 women, mean age of 67 +/- 10 years) with coronary artery disease, who underwent ICD implantation in accordance with the AHA/ACC/NASPE guidelines between January 2000 and July 2003 were included in the study. Follow-up was performed every three to six months, when all ICD therapies were documented. This documentation was used for analysis of adequate or inadequate ICD therapies. RESULTS: The mean follow-up time was 383 +/- 195 days. The time to the first adequate therapy was 201 +/- 283 days. The cumulative incidence for the first adequate therapy was 21% at six months, 39% at two years and 59% at four years. In 64% of patients, who experienced adequate ICD therapies, antitachycardia pacing (ATP) and in 36% an initial shock was delivered. ATP was successful in 83% of adequately delivered episodes. In the follow-up period 12 patients died. CONCLUSION: The benefit of the ICD was apparent in patients at risk for ventricular arrhythmias and coronary artery disease after a relatively short period of time, which underlines the important role of the ICD in primary and secondary prevention.

[Ventricular tachycardia--etiology, mechanisms and therapy]. / Kammertachykardien--Atiologie, Mechanismen, Therapie.

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.