Automated isochronal late activation mapping for substrate characterization in patients with repaired tetralogy of Fallot

Abstract

Aims Slow conduction (SC) anatomical isthmuses (AIs) are the dominant substrate for monomorphic ventricular tachycardia (VT) in patients with repaired tetralogy of Fallot (rTF). This study aimed to evaluate the utility of automated propagational analysis for the identification of SC-AI in patients with rTF. Methods and results Consecutive rTF patients undergoing VT substrate characterization were included. Automated isochronal late activation maps (ILAM) were obtained with multielectrode HD Grid Catheter. Identified deceleration zones (DZs) were compared with both SC-AI defined by conduction velocity (CV) (<0.5 m/s) and isthmuses of induced VT for mechanistic correlation. Fourteen patients were included (age 48; p25–75 35–52 years; 57% male), 2 with spontaneous VT and 12 for risk stratification. Nine VTs were inducible in seven patients. Procedure time was 140 (p25–75 133–180) min and mapping time 29.5 (p25–75 20–37.7) min, using a median of 2167 points. All the patients had at least one AI by substrate mapping, identifying a total of 27 (11 SC-AIs). Isochronal late activation maps detected 10 DZs mostly in the AI between ventricular septal defect and pulmonary valve (80%). Five patients had no DZs. A significant negative correlation between number of isochrones/cm and CV was observed (rho −0.87; P < 0.001). Deceleration zones correctly identified SC-AI (90% sensitivity; 100% specificity; 0.94 accuracy) and was related to VT inducibility (P = 0.006). Deceleration zones co-localized to the critical isthmus of induced VTs in 88% of cases. No complications were observed. Conclusion Deceleration zones displayed by ILAM during sinus rhythm accurately identify SC-AIs in rTF patients allowing a safe and short-time VT substrate characterization procedure.

Before it is too late: pre-emptive ablation strategies in tetralogy of Fallot

“…Its narrative illuminates how our understanding of the disease, the interventions that modify it, and the decision-making for future directions are interrelated. This motif extends into the work presented by Arana-Rueda et al 1 in this issue of Europace .…”

“…In their work, Arana-Rueda et al 1 introduce an innovative and novel application of automated isochronal late activation mapping (ILAM) for substrate characterization and ablation in a small series of 14 patients with repaired TOF. While ILAM is an established technique for mapping and ablating adult ventricular tachycardia (VT), 2 its use in CHD marks a significant departure from previous applications.…”