Mechanism and outcomes of catheter ablation for ventricular tachycardia in adults with repaired congenital heart disease

Background Repaired congenital heart disease (rCHD) is strongly associated with ventricular tachycardia (VT) as an important late cause of morbidity and mortality. Ventricular reentry most commonly includes anatomic isthmuses created during the repair procedures. Objective The purpose of this study was to analyze the long-term outcomes of catheter ablation, a commonly used standalone or adjunctive therapy, in a cohort of rCHD patients. Methods A retrospective analysis of 21 consecutive patients with rCHD (45.0 ± 3.0 years, 71.4% male) undergoing ablation for VT was performed. The primary composite outcome was defined as in-hospital arrhythmic death, out-of-hospital sudden cardiac death, or appropriate implantable cardioverter-defibrillator therapy. Results At initial electrophysiologic study, 14 patients (66.7%) had reentrant VT through an electroanatomic isthmus; the remaining 7 patients (33.3%) demonstrated focal VT. Isthmus-dependent reentry was identified as the mechanism for VT in 14 patients (66.7%), and conduction block was confirmed in 8 of these patients (57.1%). No patients with confirmed block developed VT recurrence. During long-term follow-up (33 ± 7 months), 20 of 21 patients (95.2%) had not reached the primary composite outcome. Three patients died of nonarrhythmic causes. Conclusion Catheter-based VT ablation in patients with rCHD is associated with a low rate of VT recurrence. Focal VT was not uncommon in this cohort. If a reentrant mechanism is present, confirmation of conduction block across the isthmus is vital to prevent recurrence.