Should Cryoablation be the Preferred Therapy for Atrioventricular Nodal Reentrant Tachycardia in Pediatric Patients?

John Papagiannis, Daniel Beissel, Dianna Newton, Jennifer Panuco, Svjetlana Tisma-Dupanovic
Pediatric Cardiology, Children's Mercy Hospital, USA

Aims: The best method for the ablation of AV nodal reentrant tachycardia (AVNRT) in children is still a matter of debate. Cryoablation (CRA) is considered safer, but its efficacy compared to radiofrequency (RFA) is thought to be lower. We sought to answer this question by reviewing our institutional experience with CRA for the treatment of AVNRT in children.

Methods and Results: Our entire institutional experience of all patients who were treated exclusively with CRA for AVNRT and were less than 20 years of age was reviewed. Clinic notes and EP procedure reports were reviewed. The NavX system was used to assist catheter navigation and reduce fluoroscopy exposure. Elimination of slow pathway was the goal, but if that was not achieved, non-inducibility was the end-point.

There were 76 patients [4-19 (12.7±3.4) years of age, weights 15.2-108 (54±19.3) kg], who were treated exclusively with CRA. Two patients had congenital heart disease and 5 had additional extranodal accessory pathways. Forty eight (61%) had received at least one antiarrhythmic medication. There were 81% patients with typical AVNRT, 9.5% with atypical and 9.5% with both forms. The acute success rate was 100%. Fluoroscopy time was 10.5±7.5 min and number of cryolesions 12.5±8.2. There was one episode of transient AV block that resolved after 3 days. Over 1-52 (13.5) months of follow-up, recurrence rate was 3.9%, with successful ablation in all 3 patients with repeat procedures (2 RFA, one CRA). The only difference between patients with recurrences and those without recurrences was the time of cryoablation which appeared to be shorter (2528 sec with recurrence vs 3078 without recurrence), but due to the small numbers, statistical significance cannot be proven. With increased experience, there has been only one recurrence in the last 5 years.

Conclusions: Cryoablation appears to have excellent acute success in treatment of AVNRT. Recurrence rates are very low and similar to radiofrequency ablation. The duration of cryoablation may play a role in reduction of recurrences.