Catheter Ablation of Ventricular Tachycardia in Structural Heart Disease: Indications, Strategies, and Outcomes-Part II. J Am Coll Cardiol. 2017;70:2924-2941. [PMID: 29216988 DOI: 10.1016/j.jacc.2017.10.030]

Characteristics of ventricular intracardiac electrograms of ventricular tachycardias originating from the epicardia in patients with an implantable cardioverter defibrillator

INTRODUCTION

While characteristic waveforms of 12-lead electrocardiograms have been reported to predict the epicardial origin of ventricular tachycardia (VT), it has not been fully examined whether ventricular intracardiac electrograms (VEGMs) recorded from the implantable cardioverter defibrillator (ICD) via telemetry can determine the origin of VT or not. The aim of this study was to investigate the VEGM characteristics of VT originating from the epicardia.

METHOD AND RESULTS

Intracardiac VEGMs of the induced VTs, with detected sites of origin during the VT study, were recorded in 15 (23 VTs) of the 46 patients. The characteristics of the 23 VTs were evaluated using far-field and near-field VEGMs recorded via telemetry. Five of 23 VTs were found to be focused on the epicardial site (epi group) and 18 VTs were focused on the endocardium (endo group). VTs of the epi group had longer VEGM duration in far-field EGM than those of the endo group (epi group: 240 ± 49 ms vs endo group: 153 ± 45 ms; P = 0.002) and the duration from the onset to the peak of VEGM was also longer than that of the endo group (epi group: 153 ± 53 ms vs endo group: 63 ± 28 ms; P < 0.001). There was no difference in the V wave duration in tip-ring EGM between both groups (epi group: 122 ± 52 ms vs endo group: 98 ± 6 ms; P = 0.377).

CONCLUSION

Evaluation of intracardiac VEGM before VT ablation may be helpful to predict the epicardial origin of VT in patients with an ICD.

Whole-Exome Sequencing Identifies a Novel Mutation (p.L320R) of Alpha-Actinin 2 in a Chinese Family with Dilated Cardiomyopathy and Ventricular Tachycardia

Dilated cardiomyopathy (DCM) is a severe cardiovascular disease which can lead to heart failure and sudden cardiac death (SCD). The typical feature of DCM is left ventricular enlargement or dilatation. In some conditions, DCM and arrhythmia can occur concurrently, apparently promoting the prevalence of SCD. According to previous studies, mutations in more than 100 genes have been detected in DCM and/or arrhythmia patients. Here, we report a Chinese family with typical DCM, ventricular tachycardia, syncope, and SCD. Using whole-exome sequencing, a novel, likely pathogenic mutation (c.959T>G/p.L320R) of actinin alpha 2 (ACTN2) was identified in all affected family members. This novel mutation was also predicted to be disease-causing by MutationTaster, SIFT, and Polyphen-2. Our study not only expands the spectrum of ACTN2 mutations and contributes to the genetic diagnosis and counseling of the family, but also provides a new case with overlap phenotype that may be caused by the ACTN2 variant.

Outcomes of patients admitted with ventricular arrhythmias and sudden cardiac death in the United States

BACKGROUND

Mortality caused by ventricular arrhythmias (VAs) remains a problem of epidemic proportions. Understanding current trends on admission of VA, patient characteristics, morbidity, mortality, and health care utilization could help us improve allocation of health care resources and risk prediction.

OBJECTIVE

The purpose of this study was to investigate clinical outcomes of VA, including ventricular tachycardia (VT), implantable cardioverter-defibrillator (ICD) shocks, and sudden cardiac death (SCD); and to identify predictors of morbidity and mortality, patterns of utilization of ICD and VT ablation, and the impact of such metrics on overall health care utilization.

METHODS

From 2010-2015, we identified 290,998 VA hospitalizations, which were stratified into group 1: normal heart; group 2: ischemic heart disease (IHD); group 3: nonischemic heart disease (non-IHD); group 4: ICD shocks; and group 5: SCD (cardiac arrest without ICD shock).

RESULTS

The number of admissions for VA decreased during the study period (except for patients with SCD and ICD shock, which increased); in-hospital mortality in patients admitted with VA and SCD increased; utilization of VT ablation in patients with ICD shocks and IHD increased; ICD implantation decreased in non-IHD patients and IHD patients; and admission for SCD was the strongest predictor of in-hospital mortality, followed by patients with non-IHD, patients with ICD shocks, and all patients with a Charlson comorbidity index ≥2.

CONCLUSION

We report a decrease in admissions for VA, decreased ICD utilization, a change in pattern of VT ablation utilization, and an increase of in-hospital mortality in SCD patients. Predictors of adverse outcomes identified in our study should be considered when developing risk models for patients undergoing risk assessment for SCD.

Novel approaches for the treatment of ventricular tachycardia

Ventricular tachycardia (VT) is a crucial cause of sudden cardiac death (SCD) and a primary cause of mortality and morbidity in patients with structural cardiac disease. VT includes clinical disorders varying from benign to life-threatening. Most life-threatening episodes are correlated with coronary artery disease, but the risk of SCD varies in certain populations, with various underlying heart conditions, specific family history, and genetic variants. The targets of VT management are symptom alleviation, improved quality of life, reduced implantable cardioverter defibrillator shocks, prevention of reduction of left ventricular function, reduced risk of SCD, and improved overall survival. Antiarrhythmic drug therapy and endocardial catheter ablation remains the cornerstone of guideline-endorsed VT treatment strategies in patients with structural cardiac abnormalities. Novel strategies such as epicardial ablation, surgical cryoablation, transcoronary alcohol ablation, pre-procedural imaging, and stereotactic ablative radiotherapy are an appealing area of research. In this review, we gathered all recent advances in innovative therapies as well as experimental evidence focusing on different aspects of VT treatment that could be significant for future favorable clinical applications.

Decompensated Heart Failure With Ventricular Arrhythmia: How Useful Is VT Ablation?

PURPOSE OF REVIEW

Ventricular arrhythmias are common in patients with heart failure. Their management especially in the context of decompensated heart failure poses a clinical challenge to modern cardiologists. In this review article, we aim to summarise the current evidence on the epidemiology, pathophysiology, and management of ventricular tachycardia in heart failure, focusing primarily on the use of catheter ablation.

RECENT FINDINGS

The evolution of electro-anatomical mapping techniques and ablation catheter technology in the recent years has paved the path for the successful application of catheter ablation in the treatment of ventricular arrhythmias. The efficacy of catheter ablation in the management of ventricular tachycardia in patients with chronic heart failure has recently been the epicentre of a number of randomised controlled trials, demonstrating promising results with regard to arrhythmia suppression and all-cause mortality. The usefulness of catheter ablation in decompensated heart failure has been explored to a lesser degree, primarily in the setting of an electrical storm. Implantable cardiac defibrillators play the most important role in improving prognosis and preventing sudden cardiac death in patients with heart failure. Catheter ablation for the treatment of recurrent VT in patients with chronic heart failure is an efficacious strategy that can be applied adjunctively to or in instead of antiarrhythmic therapy, and it is highly successful at preventing recurrent ventricular tachycardia, ICD shocks. Its efficacy in the context of decompensated heart failure requires further research, with current evidence rendering its use promising.

Editor-in-Chief's Top Picks From 2017

Each week, I record audio summaries for every article in JACC, as well as an issue summary. While this process has been time-consuming, I have become quite familiar with every paper that we publish. Thus, I personally select papers (both original investigations and review articles) from 15 distinct specialties each year for your review. In addition to my personal choices, I have included manuscripts that have been the most accessed or downloaded on our websites, as well as those selected by the JACC Editorial Board members. In order to present the full breadth of this important research in a consumable fashion, we will present these manuscripts in this issue of JACC. The highlights comprise the following sections: Basic & Translational Research, Cardiac Failure, Cardiomyopathies/Myocardial & Pericardial Diseases, Cardio-oncology, Congenital Heart Disease, Coronary Disease & Interventions, CVD Prevention & Health Promotion, Hypertension, Imaging, Metabolic & Lipid Disorders, Rhythm Disorders, Valvular Heart Disease, and Vascular Medicine (1-110).

Unsolved Questions on the Anatomy of the Ventricular Conduction System

We reviewed the anatomical characteristics of the conduction system in the ventricles of human and ungulate hearts and then raised some questions to be answered by clinical and anatomical studies in the future. The ventricular conduction system is a 3-dimensional structure as compared to the 2-dimensional character of the atrial conduction system. The proximal part consisting of the atrioventricular node, the bundle of His and fascicles are groups of conducting cells surrounded by fibrous connective tissue so as to insulate from the underlying myocardium. Their location and morphological characters are well established. The bundle of His is a cord like structure but the left and right fascicles are broad at the proximal and branching at the distal part. The more distal part of fascicles and Purkinje system are linear networks of conducting cells at the immediate subendocardium but the intra-mural network is detected at the inner half of the ventricular wall. The papillary muscle also harbors Purkinje system not in the deeper part. It is hard to recognize histologically in human hearts but conducting cells as well as Purkinje cells are easily recognized in ungulate hearts. Further observation on human and ungulate hearts with myocardial infarct, we could find preserved Purkinje system at the subendocardium in contrast to the damaged system at the deeper myocardium. Further studies are necessary on the anatomical characteristics of this peripheral conduction system so as to correlate the clinical data on hearts with ventricular arrhythmias.