Pediatric/Adult Congenital Heart Disease -> Adult Congenital Heart Disease D-AB31 - ACHD and Pediatric EP (ID 29) Abstract

D-AB31-04 - Systematic Invasive Electrophysiology Protocol For Risk Stratification And Treatment Of Ventricular Arrhythmias In Patients With Repaired Tetralogy Of Fallot (ID 1440)


Background: Patients with repaired Tetralogy of Fallot (rTOF) are at increased risk of ventricular arrhythmias (VA) and slow conducting anatomic isthmuses (SCAI) have been implicated as the arrhythmogenic substrate.
Objective: To evaluate arrhythmic outcomes in patients with rTOF undergoing systematic invasive EPS protocol with guided catheter and/or surgical ablation of SCAI.
Methods: The study cohort included 20 patients with rTOF (33±10 years, 55% female, QRS 165±5 ms, age at total repair 2.3±2.9 years, LVEF 60±8%, RVEDVI 161±49 ml/m2) who underwent invasive EPS between 2015-2019. Standardized protocol included programed stimulation and characterization of SCAI was performed (abnormal conduction velocity index < 0.5 m/s). When inducible, entrainment and/or pacemapping from SCAI was used to guide catheter and/or surgical ablation.
Results: At baseline, 40% (n=8) of patients had a history of sustained VA, 25% (n=5) had an ICD, and a minority were treated with AADs (n=5; 25%). Monomorphic VT was inducible in 45% (n=9; VT CL 298±57 ms) and SCAI were identified in 60% (n=12) (Figure). Over a mean follow-up of 2.0±1.8 years, arrhythmia-free survival in patients without SCAI (n=8) was 100%, whereas it was 80% in those with SCAI treated with catheter ablation and 71% in SCAI treated with surgical ablation (Figure). In patients with recurrent VT (n=3), repeat EPS demonstrated VT isthmuses remote from the endocardium (n=2) or adjacent to SCAI (n=1).
Conclusion: In patients with rTOF, the absence of SCAI was associated with VA-free survival. Targeting SCAI may be a promising approach to mitigate VA risk in rTOF although arrhythmic substrate may be inaccessible in a minority.