Catheter ablation for atrioventricular nodal reentry tachycardia in children: A time to freeze, and a time to burn

Abstract

Radiofrequency (RF) catheter ablation is a well-established therapy for most supraventricular tachycardias in children, including atrioventricular nodal reentry tachycardia (AVNRT). The excellent results of RF ablation have been verified in large cohorts of children in both the retrospective Pediatric Radiofrequency Ablation Registry and the multicenter Prospective Assessment after Pediatric Cardiac Ablation. 1,2 However, RF ablation for AVNRT carries a small risk of inadvertent injury to the AV node, with resulting permanent heart block. This is a dreaded complication, particularly as the targeted arrhythmia is troublesome but not life threatening. With the emergence of catheter-based cryoablation systems, many have adopted this approach for children with AVNRT because of its potential advantages. The ability to “cryomap” or assess the result of a lesion while the effects are still reversible represents perhaps the most desirous aspect for interventional electrophysiologists. Initial reports of cryoablation for treatment of AVNRT in children demonstrated the safety of the technique, but they also revealed lower acute success rates and higher recurrence rates compared with the results of RF ablation reported in the large multicenter trials. 3‐5 In a study in this issue of Heart Rhythm, Collins et al 6 directly compare radiofrequency energy and cryothermal energy for catheter ablation of AVNRT in 117 children at a single high-volume center. This group has been a leader in our efforts to better understand the aspects of AVNRT unique to children. In the present study, they confirm that both RF ablation and cryoablation can successfully and safely treat AVNRT in children. The 95% success rate of cryoablation in this study was high, with only one true failure requiring crossover to RF ablation for procedural success. The two other failures were aborted procedures because of malfunction of the cryoablation console and first-degree heart block induced with catheter manipulation. The latter may be due to the size and stiffness of the current generation of cryoablation catheters. With continued use and refinement, cryoablation of AVNRT in children likely will attain the high success rate currently enjoyed by RF ablation (100% in the present study). The recurrence rates were 2% for RF ablation and 8% for cryoablation, but this study was too small to detect a significant difference between groups. Nonetheless, the results are consistent with the higher recurrence rates reported in previous studies evaluating cryoablation. 4,7