Copyright © Italian Federation of Cardiology. Unauthorized reproduction of this article is prohibited. Acute and long-term outcome of transvenous cryothermal catheter ablation of supraventricular arrhythmias involving the perinodal region Fiorenzo Gaita a , Antonio Montefusco a , Riccardo Riccardi a,b , Marco Scaglione a , Stefano Grossi b , Domenico Caponi a , Enrico Caruzzo b , Carla Giustetto a , Mario Bocchiardo a and Paolo Di Donna a Objective Cryoenergy is a new valuable treatment option to perform ablation close to the atrioventricular (AV) node in the cure of supraventricular tachycardias because of its favourable properties, such as the possibility of creating reversible lesions. The aim of this study was to report our experience on the effectiveness and safety of catheter cryoablation performed in ‘‘critical areas’’ to treat a large cohort of patients with supraventricular arrhythmias. Methods One hundred and thirty-one patients suffering from supraventricular tachycardias underwent catheter cryoablation using a 7F catheter. Eighty-seven patients presented with AV nodal re-entrant tachycardia (AVNRT), 39 had accessory pathways (APs) either manifest or concealed (15 midseptal, 24 parahissian), three had ectopic right atrial tachycardia (AT), and two patients had a permanent junctional reciprocating tachycardia (PJRT). When the optimal parameters were recorded, ice mapping at S30-C was performed for 80 s to validate the ablation site. If the expected result occurred, cryoablation was carried out by lowering the temperature to S75-C for 4 min. Results In two patients cryoablation was not performed because of technical reasons. Cryoablation was acutely successful in 84 out of 85 patients with AVNRT, in 37 of 39 with APs and in all patients with AT and PJRT. No complications occurred in any patient. Transient AV conduction impairment occurred in seven patients with midseptal APs and in two patients with AVNRT. In particular, in these patients no late permanent AV block was observed at follow-up. At a mean follow-up of 27 W 12.9 months, clinical success rate was 87%. Conclusions Cryoablation is a safe and effective technique with a high success rate in the long term. It may be particularly useful when performing ablation close to the AV node or His bundle owing to the possibility of validating the ablation site with ice mapping, which creates only a reversible lesion, mainly in the midseptal APs. J Cardiovasc Med 7:785–792 Q 2006 Italian Federation of Cardiology. Journal of Cardiovascular Medicine 2006, 7:785–792 Keywords: cryoablation, supraventricular tachycardia, Wolff–Parkinson– White syndrome a Division of Cardiology, Cardinal Massaia Hospital, Asti and b Division of Cardiology, Mauriziano Hospital, Turin, Italy Correspondence and requests for reprints to Dr Fiorenzo Gaita, Division of Cardiology, Cardinal Massaia Hospital, Corso Dante 202, 14100 Asti, Italy Tel: +39 0141 482171; fax: +39 0141 487134; e-mail: gaitaf@libero.it Received 1 September 2005 Revised 19 December 2005 Accepted 20 December 2005 Radiofrequency (RF) catheter ablation has been shown to be a safe and effective treatment to cure cardiac arrhythmias and can be considered as first-line therapy in most cases. However, a small but definite risk of complications has been reported in different series of patients undergoing a RF ablation procedure [1–3]; in particular, when ablation is performed in critical regions such as the septum close to the atrioventricular (AV) node or His bundle, a significant risk of heart block is present [2,3]. Furthermore, the risk of late permanent AV block has been correlated with the occurrence of transient impairment of AV conduction during RF ablation [4,5]. Cryoenergy has widely been used in the past for the treatment of arrhythmias during surgery [6,7] and it has recently been shown to be effective in the cure of atrial fibrillation with a limited linear ablation in the left atrium during heart surgery [8,9]. Cryoenergy shows several valuable properties: it produces a homogeneous and well demarcated lesion with no endocardial disruption [10] and avoids catheter dislodgement thanks to its strong adherence to the endocardial tissue during cryoablation. More importantly, using cryoenergy, it is possible to predict the effectiveness and safety of the lesion since a transient and reversible lesion is created before additional cooling determines an irreversible one [11]. The effectiveness and safety of this technique compared with RF have recently been reported performing nodal slow pathway transcatheter ablation [12,13]. On the basis of these considerations, catheter-based cryotherapy Original article 1558-2027 ß 2006 Italian Federation of Cardiology