MP-453092-5 ISOCHRONAL LATE ACTIVATION MAPPING FOR TARGETED ABLATION OF VENTRICULAR TACHYCARDIA IN PATIENTS WITH TETRALOGY OF FALLOT

Patients with tetralogy of Fallot (ToF) have an increased risk reentrant ventricular arrhythmias (VAs) utilizing slowly conducting anatomic isthmuses (SCAIs). Isochronal late activation mapping (ILAM) is alternative technique that identifies deceleration zones (DZ) during sinus and paced rhythms. These areas been shown to be candidate sites for arrhythmias. Assess feasibility ablation targeting DZs identified by ILAM rhythms among patients ToF VAs. ≥25 y/o planned surgical or transcatheter pulmonary valve replacement (PVR) underwent stimulation study prior PVR (PPVR EPS). Voltage maps sinus/RV were created high-density catheters. SCAIs defined as voltage <1.5 mV <0.5 m/s between boundaries. Ablation DZ (>3 isochrones within 1 cm radius) was performed in all inducible VT/VF. As able, VT successful compared locations mechanistic correlation. Eighteen (median age 40.7 years [36-48], 56% female) PPVR EPS. Ten (56%) had VA. High-density a mean 5049 points [4580-5523] rhythm, 2518 [1615-3752] RV pacing). A 2 [1-3] per patient. correlated traditional 68% patients. Alternate including anterior (20%) lateral (12%) free-wall also identified. VA bidirectional block across (successful 97%) covering non-SCAI areas. Seven (70%) non-inducible following ablation. Activation could two termination at both (one SCAI one DZ). No sustained detected 9 [2-16] months follow-up. functional substrates guides targeted Regions isochronal crowding while identifying predictive success.