Accessory pathways (AP) is the most common etiology of supraventricular tachycardia in children. Actually, ablation of AP has become common, with very few complications and excellent results. Localization prior to ablation is very important in order to prepare the procedure, consider the approach (femoral/transsepta/retroaortic), energy used and estimate success rate and risk of complications. Paumbrun et al. have created an algorithm based on the aspect of maximum pre-excitation obtained during an electrophysiological study with rapid atrial pacing, but this algorithm has only been tested in patients over 15 years.

The aim is to validate the maximal pre-excitation based algorithm of Paumbrun in a paediatric population.

Among ablations performed between 2018 and 2022, 123 patients under 16 years of age were admitted to our center for ablation of a permanent patent accessory pathway. Patients were excluded if electrophysiological exploration revealed multiple accessory pathways, atypical or non-atrioventricular accessory pathways, or if ablation failed. Atrial pacing was performed from the right atrium or coronary sinus at increasing frequency until maximum pre-excitation was achieved. The reference location was defined according to a radiological classification in OAG 45–50° view or on 3D mapping; it corresponded to the site at which the ablation shot enabled prolonged disappearance of pre-excitation. Localization on the surface ECG was defined according to the St Georges algorithm.

The study population consisted of 123 patients aged under 16 years; mean age was 12 years, with an history of arrythmia-induced cardiomyopathy in 1.6%. The most frequent locations was left lateral (29%) and right postero-septal (26%).

The averaged sensitivity, specificity, positive and negative predictive values of these 2 algorithms for each localization are summarized in Table 1. Regarding the accuracy, AP localizations were correctly identified in 83% of patients with the maximal pre-excitation based algorithm and 40% of patients with St Georges algorithm (P<0.001).

Our study shows that the analysis of maximal pre-excitation allows accurate localization of manifest APs for a pediatric population, even for right-sided or nodo-hisian location.