Abstract 4357661: Outcomes of Ventricular Tachycardia Ablation in Patients with Baseline Noninducibility

Background: Ventricular tachycardia (VT) induction identifies targets for ablation and is an important procedural endpoint. Ablation approaches and outcomes for patients noninducible for VT at baseline are not well described. Research question: What are the procedural characteristics and outcomes for patients presenting for VT ablation with baseline noninducibility? Methods: Patients at a single VT referral center who were noninducible at the start of a VT ablation procedure were retrospectively identified. All procedures were performed under monitored sedation. Baseline induction consisted of programmed stimulation with up to 4 extrastimuli from 2 or more ventricular sites at 2 or more drive cycles with or without isoproterenol. Ablation strategies, procedural outcomes, and long-term results were characterized. Results: A total of 27 of 160 patients referred for ablation were identified to have baseline noninducibility for VT (mean age 59 ± 13 years, 81% male, mean left ventricular ejection fraction 48 ± 16%, ischemic cardiomyopathy 41%, nonischemic cardiomyopathy 30%, Table). Prior ablation had been performed in 10/27 (37%) and 20/27 (74%) were previously treated with antiarrhythmic drugs (AADs). Mapping strategies included pace mapping of device electrograms (14/23, 61%) or prior EKGs (1/23, 4%) and pace or activation mapping of premature ventricular complexes perceived to match the clinical VT (13/23, 57%). Ablation of low voltage, fractionated, or late electrogram regions was performed in 6/27(22%). Ablation based on cardiac magnetic resonance imaging (CMR)-identified myocardial scar was performed in 7/27 (26%). VT remained noninducible in 22/23 (96%) of patients where programmed stimulation was repeated after ablation. One patient had arterial pseudoaneurysm following ablation, treated with thrombin injection. Mean follow-up was 1100 ± 967 days. VT recurred in 6/27 (22%) with a mean of 462 ± 466 days until first appropriate implantable cardioverter-defibrillator (ICD) therapy (Figure). At last follow-up, AADs were continued in 13/27 (48%) patients but had been discontinued or reduced in 16/20 (85%) prescribed AADs pre-ablation. A total of 5/27 (19%) of patients died during follow-up at a mean of 1229 ± 652 days after ablation. Conclusion: VT ablation in patients noninducible at baseline was feasible and well-tolerated with infrequent VT recurrence. Prospective studies are needed to identify optimal ablation endpoints for this population.