Introduction: Catheter ablation is the treatment of choice for patients with accessorry pathways (AP) in which the electrophysiological study revealed high-risk elements such as AP refractory period <240 ms, R-R interval during preexcited atrial fibrillation <250 ms or the presence of multiple APs. Depending on their loca-lization, APs can be difficult to ablate. Mid-septal APs have their atrial insertion in the triangle of Koch, whi-ch is also the home of the atrioventricular node. Radi-ofrequency ablation of these APs implies a high risk of developing atrioventricular block (2-10%). Cryoablation represents a much safer alternative for these pati-ents.

Objective: This case report intends to synthetize the case of a young, athlete patient with a mid-septal AP which could not be treated by RF ablation because of atrioventricular block occurrence during the procedu-re. Cryoablation was successfully performed.

Methods: We report a 22-year-old athlete patient ad-mitted to our department for multiple episodes of high rate palpitations, without being documented on ECG. ECG at admission showed preexcitation suggestive for a right AP, most probably located mid-septal. Elec-trophysiological study was performed which confir-med the mid-septal AP, having a refractory period of 220ms. We decided to perform RF ablation, but at ca-theter manipulation in the mid-septal area, 2nd degree 2:1 AV block occurred concomitant with preexcitation disappearance. Low-energy ablation was performed (5-10W) with the disappearance of preexcitation, but with prolongation of atrioventricular conduction time and preexcitation recurrence after each shot. We decided to stop the procedure and schedule the patient for cryoa-blation.

Results: Taking into account the malignant characte-ristics of the AP and the fact that athletes have a higher risk of developing arrhythmias because of increased sympathetic tonus, we considered that in this patient the definitive treatment of the AP through cryoablati-on must be performed as soon as possible. Cryoablati-on was performed one week after the first procedure, with a good final result and without preexcitation re-currence during checking maneuvers and without any atrioventricular block development. However, during the cryoablation, right bundle branch bloc developed. 6 weeks after the procedure ECG showed no preexci-tation, with right bundle branch block persistence, the patient mentioning the absence of palpitations during this period and complete reintegration in sports com-petitions.

Conclusions: Cryoablation represents a safe treatment option for patients with APs located close to the atrio-ventricular node, having a much lower rate of atrioven-tricular block compared to RF ablation. Furthermore, considering that athletes with WPW syndrome have a higher risk of developing malignant arrhythmias, cryoablation may be the best therapeutic option for these patients.