B-po01-073 multicenter outcomes of catheter ablation for atrioventricular reciprocating tachycardia via twin atrioventricular nodes: a pediatric and congenital electrophysiology society (paces)/international adult congenital heart disease (isachd) collaborative study

Although a well-described entity, there are few data on the electrophysiologic properties and outcomes of catheter ablation for AV reciprocating tachycardia via twin AV nodes (T-AVRT). To identify the anatomical substrates and determine the outcomes of catheter ablation for T-AVRT. An international, multicenter study was performed to collect retrospective procedural and outcome data for catheter ablation of T-AVRT. Data were transferred to the coordinating center for review. Forty-five patients with T-AVRT were identified (median age 8.7, IQR 4.9 - 18.2). Of these, 43 (98%) were diagnosed with heterotaxy syndrome (right atrial isomerism in 28, left atrial isomerism in 3 and ambiguous in 10). Twenty (44%) had undergone Fontan operation (12 extracardiac, 7 lateral tunnel and 1 Kawashima). After Fontan, atrial access was by conduit/baffle puncture in 14 (70%), fenestration in 3 (15%), retrograde in 2 (10%), and transhepatic in 1 with interrupted IVC (5%). The median AV Wenckebach cycle length was similar for anterior vs posterior AV nodes (300 ms vs 275 ms, respectively; p=n.s.) In 39 patients with attempted catheter ablation, the aAVN was targeted in 20 (51%) and the pAVN in 19 (49%). The targeted AV node served as the posterior limb of the T-AVRT circuit in 33 of 36 with inducible tachycardia. Acute success was achieved in 36 of 39 (92%). Overall, there were 2 complications, consisting of 1) first degree AV block when targeting both twin T-AVRT and typical AVNRT and 2) episodes of polymorphic VT during isoproterenol administration requiring lidocaine and defibrillation. There were no cases of advanced AV block. Post-ablation, the QRS duration was unchanged vs baseline (92 vs 95 ms, p=n.s.). Over a median of 3.9 yrs, there were 3 recurrences. Of 6 patients with either failed index procedure or recurrent T-AVRT, 5 (83%) were associated with anatomic hurdles such as prior Fontan or catheter course through an interrupted IVC-to-azygous continuation. T-AVRT can be targeted successfully with low risk for recurrence. Complications were rare in this population. Anatomical challenges appear to be associated with reduced acute and long-term efficacy and represent opportunities for improvements in procedural timing and planning.