Catheter ablation of coronary sinus accessory pathways in the young.

Background: Accessory atrioventricular pathways (APs) are the most common tachycardia substrate for supraventricular tachycardia (SVT) in the young. Endocardial catheter ablation of AP may be unsuccessful in up to 5% of patients because of a coronary sinus location.

Objective: The purpose of this study was to obtain data on ablation of accessory pathways within the coronary venous system (CVS) in the young.

Methods: Analysis of feasibility, outcome, and safety in patients ≤18 years with coronary sinus accessory pathways (CS-APs) and catheter ablation via CVS in a tertiary pediatric electrophysiological referral center (May 2003 to December 2021) was performed. The control group adjusted for age, weight, and pathway location was established from patients of the prospective European Multicenter Pediatric Ablation Registry who all had undergone endocardial AP ablation.

Results: Twenty-four individuals underwent mapping and intended AP ablation within the CVS (age 2.7-17.3 years; body weight 15.0-72.0 kg). Because of proximity to the coronary artery, ablation was withheld in 2 of the patients. Overall procedural success was achieved in 20 of 22 study patients (90.9%) and in 46 of 48 controls (95.8%). Coronary artery injury after radiofrequency ablation was noted in 2 of 22 study patients (9%) and in 1 of 48 controls (2%). In CVS patients, repeat SVT occurred in 5 of 22 patients (23%) during median follow-up of 8.5 years, and 4 of the 5 underwent reablation, resulting in 94.4% overall success. Controls were free from SVT during follow-up of 12 months as defined by the registry protocol.

Conclusion: Success of CS-AP ablation in the young was comparable to that of endocardial AP ablation. Substantial risk of coronary artery injury should be considered when CS-AP ablation is performed in the young.