Tachyarrhythmias in Koch's triangle: to be burned out or to be cool?

Radiofrequency (RF) ablation has proven to be highly effective in the treatment of tachyarrhythmias in Koch’s triangle. Despite this successful approach, several disadvantages can be expected, such as patient discomfort, coagulum formation on the electrode, intralesional haemorrhage, endocardial disruption leading to thrombus formation, steam popping or perforation, some degree of tissue disruption with irreversible damage, and ragged edges, making it potentially arrhythmogenic. More importantly, there is an increased risk for right bundle branch block or inadvertent complete heart block. Therefore, alternative energy sources have been developed, of which cryo ablation seems to be very promising. This energy source has the ability to reversibly demonstrate loss of function with cooling to less negative temperatures (cryo mapping) so that prospective ablation sites can be investigated, before a definitive and irreversible lesion is created. 1 This should lead to less applications and abolish the risk of permanent conduction disturbances. Progressive ice formation at the catheter tip causes adherence to the adjacent tissue, making ablation safe to perform during unstable catheter position or even during tachycardia, without the risk of dislodgement of the catheter at termination of the arrhythmia. The more precise delivery of therapy due to cryo mapping and the creation of smaller lesions both in area and volume, together with the formation of a homogenous fibrosis with a proven preservation of the extracellular matrix and a well demarcated border, makes it potentially less thrombogenic and proarrhythmic. In atrioventricular nodal reentrant tachycardia (AVNRT), it is the only method to target the slow pathway on EP basis, as during cryo mapping programmed atrial stimulation can be performed to determine if the AH jump has disappeared and/or AVNRT is no longer inducible without carrying the risk of dislodgement of the catheter. 2 Of course, extensive clinical investigation is needed to evaluate these theoretical advantages. In this context, four articles have recently been published in this journal concerning cryo ablation in patients with AVNRT. 3–6.