Chronic rate dependent exit block after pulmonary vein isolation

Rate dependent exit block across the pulmonary veins has been previously described immediately following catheter ablation. We report a case of rate dependent pulmonary vein exit block seen at repeat ablation 7 years after the index procedure. To our knowledge, this is the first report of chronic rate dependent exit block discovered years after circumferential pulmonary vein antral isolation.     

Use of Three-Dimensional Mapping Systems in the Catheter Ablation of Atrial Fibrillation

The increasing clinical experience with remarkable advancement in the technology has enabled the catheter ablation of atrial fibrillation (AF) to become more effective and safe. Widespread utilization of three-dimensional (3D) mapping systems has facilitated the improvement in the outcomes after catheter ablation of AF. The purpose of this article is to review the current status, clinical role, and future directions of various 3D mapping systems in catheter ablation of AF.     

Impact of Changing Activation Sequence on Bipolar Electrogram Amplitude for Voltage Mapping of Left Ventricular Infarcts Causing Ventricular Tachycardia

Introduction: Wavefront direction is a determinant of bipolar electrogram amplitude that could influence identification of low amplitude regions indicating infarction or scar.Methods: To assess the importance of activation sequence on electrogram amplitude 11 patients with prior infarction and ventricular tachycardia were studied. At 819 left ventricular sites bipolar electrograms were recorded during atrial pacing and ventricular pacing, followed by unipolar pacing with a stimulus of 10 mA at 2 ms. Sites with a pacing threshold > 10 mA were designated electrically unexcitable scar.Results: Areas of low voltage (1.5 mV) were present in all patients. Atrial paced and ventricular paced electrogram amplitudes were strongly correlated (r = 0.77; P < 0.0001). Changing the activation sequence (from atrial pacing to ventricular pacing) produced a > 50% change in electrogram amplitude at 28% of sites and a > 100% change at 10% of sites, but only 8% of sites had an electrogram amplitude classified as abnormal (1.5 mV) with one activation sequence and normal (> 1.5 mV) with the other activation sequence. Electrically unexcitable scar (6% of sites) was associated with lower electrogram amplitude but could not be reliably identified based on electrogram amplitude alone for either activation sequence.Conclusion: Voltage maps created with bipolar recordings using these methods should be relatively robust depictions of abnormal ventricular regions despite variable catheter orientation and activation sequences that might be produced by different rhythms.     

Noninvasive risk factors for the prediction of inducibility on programmed ventricular stimulation in post‐myocardial infarction patients with an ejection fraction ≥40% at risk for sudden cardiac arrest: Insights from the PRESERVE‐EF study

BackgroundIn the PRESERVE‐EF study, a two‐step sudden cardiac death (SCD) risk stratification approach to detect post‐myocardial infarction (MI) patients with left ventricle ejection fraction (LVEF) ≥40% at risk for major arrhythmic events (MAEs) was used. Seven noninvasive risk factors (NIRFs) were extracted from a 24‐h ambulatory electrocardiography (AECG) and a 45‐min resting recording. Patients with at least one NIRF present were referred for invasive programmed ventricular stimulation (PVS) and inducible patients received an Implantable Cardioverter ‐ Defibrillator (ICD).MethodsIn the present study, we evaluated the performance of the NIRFs, as they were described in the PRESERVE‐EF study protocol, in predicting a positive PVS. In the PRESERVE‐EF study, 152 out of 575 patients underwent PVS and 41 of them were inducible. For the present analysis, data from these 152 patients were analyzed.ResultsAmong the NIRFs examined, the presence of signal averaged ECG‐late potentials (SAECG‐LPs) ≥ 2/3 and non‐sustained ventricular tachycardia (NSVT) ≥1 eposode/24 h cutoff points were important predictors of a positive PVS study, demonstrating in the logistic regression analysis odds ratios 2.285 (p = .027) and 2.867 (p = .006), respectively. A simple risk score based on the above cutoff points in combination with LVEF < 50% presented high sensitivity but low specificity for a positive PVS.ConclusionCutoff points of NSVT ≥ 1 episode/24 h and SAECG‐LPs ≥ 2/3 in combination with a LVEF < 50% were important predictors of inducibility. However, the final decision for an ICD implantation should be based on a positive PVS, which is irreplaceable in risk stratification.     

Influence of Clinical and Procedural Predictors on Ventricular Tachycardia Ablation Outcomes: An Analysis From the Substrate Mapping and Ablation in Sinus Rhythm to Halt Ventricular Tachycardia Trial (SMASH‐VT)

Procedural Predictors in SMASH‐VT . Background: The Substrate Mapping and Ablation in Sinus Rhythm to Halt Ventricular Tachycardia (SMASH‐VT) trial is the largest randomized trial in substrate‐based ablation. We performed a retrospective analysis of patients randomized to prophylactic ablation of ventricular tachycardia to determine the predictive value of clinical and procedural variables on outcomes. Methods: In patients treated with catheter ablation, we examined predictors of ICD‐therapy free survival using Cox proportional hazards models. Procedural variables tested included the scar location, number of VT morphologies (VTs) induced, tachycardia cycle length, catheter irrigation, catheter approach, procedural duration, and VT inducibility after ablation. Clinical variables including age, index arrhythmia, NYHA class, ejection fraction, prior revascularization, and baseline medication use were also analyzed. Results: Among 64 patients randomized to ablation, 61 received the assigned therapy and complete procedural data were available for 54 patients. Thirteen percent (7 of 54) experienced ICD therapies during 2‐year follow‐up. Patients with subsequent ICD therapies had significantly more VTs induced during the ablation procedure than those without (3.9 ± 2.1 vs 1.9 ± 1.8, P = 0.05). The hazard ratio for each additional VT induced was 1.51 (95% CI 1.07–2.13, P = 0.02). Two‐year Kaplan–Meier event‐free survival rates were 96% for 0–1 VTs induced, and 78% for two or more. The use of irrigated catheters was not predictive of ablation success. Conclusion: In this small retrospective analysis, the number of VTs induced during the procedure was predictive of 2‐year outcomes. This likely reflects a more complex arrhythmia substrate in patients who fail ablation. (J Cardiovasc Electrophysiol, Vol. pp. 799‐803, July 2010)     

Primary Prevention of Sudden Cardiac Death in Adults with Transposition of the Great Arteries: A Review of Implantable Cardioverter-Defibrillator Placement

Transposition of the great arteries encompasses a set of structural congenital cardiac lesions that has in common ventriculoarterial discordance. Primarily because of advances in medical and surgical care, an increasing number of children born with this anomaly are surviving into adulthood. Depending upon the subtype of lesion or the particular corrective surgery that the patient might have undergone, this group of adult congenital heart disease patients constitutes a relatively new population with unique medical sequelae. Among the more common and difficult to manage are cardiac arrhythmias and other sequelae that can lead to sudden cardiac death. To date, the question of whether implantable cardioverter-defibrillators should be placed in this cohort as a preventive measure to abort sudden death has largely gone unanswered. Therefore, we review the available literature surrounding this issue.     

Prognostic Impact of Extent,Severity, and Heterogeneity of Abnormalities on 18F-FDG PET Scans for Suspected Cardiac Sarcoidosis

Objectives

This study sought to evaluate the incremental value of quantifying the extent and severity of myocardial perfusion and ¹⁸F-labeled fluorodeoxyglucose (FDG) abnormalities in predicting adverse outcomes among patients with suspicion for cardiac sarcoidosis (CS).

Mapping of ventricular arrhythmias using a novel noninvasive epicardial and endocardial electrophysiology system

Introduction

The aim of this study was to assess the use of a novel noninvasive epicardial and endocardial electrophysiology system (NEEES) for mapping of ventricular arrhythmias.