Po-04-158 intracardiac echocardiography guides anatomical isthmus ablation in patients with ventricular tachycardia and repaired tetralogy of fallot

Successful catheter ablation of monomorphic ventricular tachycardia (VT) in patients with repaired Tetralogy of Fallot (TOF) can be achieved by targeting one or more of four common anatomical isthmuses. However, variability in the size and location of surgical patches means careful mapping is required to design ablation lines to block the critical isthmus. Intracardiac echocardiography (ICE) may assist ablation by accurate identification of individual TOF anatomy. To determine whether the routine use of ICE aids linear ablation of VT isthmuses in patients with repaired TOF. Retrospective study of repaired TOF patients undergoing VT ablation at our centre from January 2017 to November 2022. Cases were divided into those which used ICE to assist anatomical mapping versus those which used voltage mapping to identify patches and valve annuli. Once anatomy was defined, we started with a VT stimulation study where haemodynamically stable VTs were mapped. Non-inducible or unstable VTs underwent substrate mapping in sinus rhythm. All cases underwent ablation and had no inducible monomorphic VT as the endpoint. Data are presented as median and [interquartile range]. Twenty-six patients were identified, of which 15 were guided by ICE. The baseline demographic data is presented in the table and a representative figure shows the use of ICE to identify surgical patches. The use of ICE allowed linear ablation of the critical anatomical isthmus in 12/15 patients (80%) compared to 4/11 (36%) without ICE (p=0.023). The remaining patients without linear ablation underwent substrate-based ablation only to sites of local abnormal ventricular activity. There was no significant difference in overall procedure time (ICE: 165 [60] minutes versus no ICE: 145 [50] minutes; p=0.24), nor in fluoroscopy time (ICE: 25 [17] minutes versus no ICE: 31 [16] minutes; p=0.9). Over time, the introduction of ICE was associated with improved workflow. When comparing the first and last five cases using ICE, both median procedure times (from 196 to 160 minutes) and fluoroscopy times (from 35 to 20 minutes) were shorter. Intracardiac echocardiography improves targeted linear ablation of the critical anatomical isthmus for VT in patients with repaired TOF. ICE provides real-time individualised identification of surgical patches and valve anatomy to guide optimal linear lesion sets across isthmuses, with routine use over time showing a trend towards shorter procedural and fluoroscopy times.Tabled 1Baseline demographicsICE (n=15)No ICE (n=11)Age (years)53 [26]41 [23]Male10 (67%)7 (64%)Number of sternotomies2 [1]3 [2]History of syncope5 (33%)1 (9%)QRS width (milliseconds)176 [59]172 [54]Left ventricular ejection fraction (%)50 [25]54 [9]Right ventricular ejection fraction (%)29 [8]27 [7]Implantable cardiac defibrillator7 (47%)5 (45%)History of sustained VT12 (80%)8 (73%)VT ablation15 (100%)11 (100%)Inducible VT at electrophysiology study11 (73%)6 (55%)Linear anatomical isthmus ablation12 (80%)4 (36%)Procedure time (minutes)165 [60]145 [50]Fluoroscopy time (minutes)25 [17]31 [16] Open table in a new tab