Background: Optimal timing for catheter ablation of ventricular tachycardia is an important unresolved issue. There are no randomized trials evaluating the benefit of ablation after the first implantable cardioverter defibrillator (ICD) shock. Methods: We conducted a 2-phase, prospective, multicenter, randomized clinical trial. Patients with ischemic or nonischemic dilated cardiomyopathy and primary or secondary prevention indication for ICD were enrolled in an initial observational phase until first appropriate shock (phase A). After reconsenting, patients were randomly assigned 1:1 in phase B to immediate ablation (within 2 months from shock delivery) or continuation of standard therapy. The primary end point was a composite of death from any cause or hospitalization for worsening heart failure. Amiodarone intake was not allowed except for documented atrial tachyarrhythmias. On July 23, 2021, phase B of the trial was interrupted as a result of the first interim analysis on the basis of the Bayesian adaptive design. Results: Of the 517 patients enrolled in phase A, 154 (30%) had ventricular tachycardia, 56 (11%) received an appropriate shock over a median follow-up of 2.4 years (interquartile range, 1.4-4.4), and 47 of 56 (84%) agreed to participate in phase B. After 24.2 (8.5-24.4) months, the primary end point occurred in 1 of 23 (4%) patients in the ablation group and 10 of 24 (42%) patients in the control group (hazard ratio, 0.11 [95% CI, 0.01-0.85]; P=0.034). The results met the prespecified termination criterion of >99% Bayesian posterior probability of superiority of treatment over standard therapy. No deaths were observed in the ablation group versus 8 deaths (33%) in the control group (P=0.004); there was 1 worsening heart failure hospitalization in the ablation group (4%) versus 4 in the control group (17%; P=0.159). ICD shocks were less frequent in the ablation group (9%) than in the control group (42%; P=0.039). Conclusions: Ventricular tachycardia ablation after first appropriate shock was associated with a reduced risk of the combined death or worsening heart failure hospitalization end point, lower mortality, and fewer ICD shocks. These findings provide support for considering ventricular tachycardia ablation after the first ICD shock.

While sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is due to arrhythmias, the guidelines for prediction of SCD are based solely on non-electrophysiological methods. This study aims to stimulate thinking about whether the interests of patients with HCM are better served by using current, ‘risk factor’, methods of prediction or by further development of electrophysiological methods to determine arrhythmic risk. Five published predictive studies of SCD in HCM, which contain sufficient data to permit analysis, were analysed to compute receiver operating characteristics together with their confidence bounds to compare their formal prediction either by bootstrapping or Monte Carlo analysis. Four are based on clinical risk factors, one with additional MRI analysis, and were regarded as exemplars of the risk factor approach. The other used an electrophysiological method and directly compared this method to risk factors in the same patients. Prediction methods that use conventional clinical risk factors and MRI have low predictive capacities that will only detect 50–60% of patients at risk with a 15–30% false positive rate [area under the curve (AUC) = ∼0.7], while the electrophysiological method detects 90% of events with a 20% false positive rate (AUC = ∼0.89). Given improved understanding of complex arrhythmogenesis, arrhythmic SCD is likely to be more accurately predictable using electrophysiologically based approaches as opposed to current guidelines and should drive further development of electrophysiologically based methods.

Introduction Thoracic impedance (TI) drops measured by implantable cardioverter‐defibrillators (ICDs) have been reported to correlate with ventricular tachycardia/fibrillation (VT/VF). The aim of our study was to assess the temporal association of decreasing TI trends with VT/VF episodes through a longitudinal analysis of daily remote monitoring data from ICDs and cardiac resynchronization therapy defibrillators (CRT‐Ds). Methods and Results Retrospective data from 2384 patients were randomized 1:1 into a derivation or validation cohort. The TI decrease rate was defined as the percentage of rolling weeks with a continuously decreasing TI trend. The derivation cohort was used to determine a TI decrease rate threshold for a ≥99% specificity of arrhythmia prediction. The associated risk of VT/VF episodes was estimated in the validation cohort by dividing the available follow‐up into 60‐day assessment intervals. Analyses were performed separately for 1354 ICD and 1030 CRT‐D patients. During a median follow‐up of 2.0 years, 727 patients (30.4%) experienced 3298 confirmed VT/VF episodes. In the ICD group, a TI decrease rate of >60% was associated with a higher risk of VT/VF episode in a 60‐day assessment interval (stratified hazard ratio, 1.42; 95% confidence interval (CI), 1.05–1.92; p = .023). The TI decrease preceded (40.8%) or followed (59.2%) the VT/VF episodes. In the CRT‐D group, no association between TI decrease and VT/VF episodes was observed (p = .84). Conclusion In our longitudinal analysis, TI decrease was associated with VT/VF episodes only in ICD patients. Preventive interventions may be difficult since episodes can occur before or after TI decrease.

Background and Aims Electroanatomical mapping may be critical to identify atrial fibrillation (AF) subjects that require substrate modification beyond pulmonary vein isolation (PVI). The objective was to determine correlations between pre-ablation mapping characteristics and 12-month outcomes after a single PVI-only catheter ablation of AF. Methods This study enrolled paroxysmal AF (PAF), early persistent AF (PsAF; 7 days-3 months) and non-early PsAF (>3 months-12 months) subjects undergoing de novo PVI-only radiofrequency catheter ablation. Sinus rhythm and AF voltage maps were created with the Advisor HD Grid™ Mapping Catheter, Sensor Enabled™ for each subject and presence of low voltage area (low voltage cutoffs: 0.1 mV-1.5 mV) was investigated. Follow-up visits were at 3-, 6- and 12-months, with a 24-hour Holter monitor at 12-months. A Cox proportional hazards model identified associations between mapping data and 12-month recurrence after a single PVI procedure. Results The study enrolled 300 subjects (113 PAF, 86 early PsAF, 101 non-early PsAF) at 18 centers. At 12-months, 75.5% of subjects were free from AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence. Univariate analysis found arrhythmia recurrence did not correlate with AF diagnosis, but low voltage area was significantly correlated. Low voltage area (<0.5 mV) greater than 28% of the left atrium in sinus rhythm (HR:4.82, 95% CI:2.08-11.18, p = 0.0003) and greater than 72% in AF (HR:5.66, 95% CI:2.34-13.69, p = 0.0001) was associated with higher risk of AF/AFL/AT recurrence at 12-months. Conclusion Larger extension of low voltage area was associated with increased risk of arrhythmia recurrence. These subjects may benefit from substrate modification beyond PVI.