Catheter-induced mechanical trauma to fast and slow pathways during radiofrequency ablation of atrioventricular nodal reentry tachycardia: Incidence, predictors, and clinical implications

Background: Data on the incidence and significance of catheter-induced trauma to fast and slow pathways are scarce. Objectives: To evaluate the incidence, predictors, and clinical implications of inadvertent catheter-induced mechanical trauma to fast and slow pathways during radiofrequency ablation (RFA) of atrioventricular nodal reentry tachycardia (AVNRT). Methods: A total of 901 consecutive patients (aged 9-92 years old) with inducible sustained AVNRT underwent RFA of the slow pathway. All procedures were closely monitored for appearance of catheter-induced mechanical block of fast or slow pathways. Results: Catheter-induced mechanical trauma to fast and/or slow pathways was observed in 121 (13.4%) patients: 86 (71%) patients had trauma of the fast pathway, three (2.4%) had trauma of the slow pathway, and 32 (26.4%) had trauma of both pathways. Mechanical trauma lasted <1 minute in 87 (72%) patients, 1-30 minutes in 23 (19%) and >30 minutes in 11 (9%). A significantly increased procedure discontinuation rate was observed in patients with mechanical trauma as compared to those with no trauma (P < 0.0001). Young patient age (<35) was a strong predictor for the occurrence of mechanical trauma to AV nodal pathways. No significant difference between the trauma and non-trauma groups was found in respect to the number of catheters used during the procedure, the incidence of AV block, and the need for permanent pacemaker implantation. Conclusions: Mechanical trauma to fast and slow pathways during ablation of AVNRT is more common than previously recognized, occurring especially in patients aged <35 years.