0049: Long-term follow- up of AV conduction disturbances after slow pathway ablation in patients with AV node reentrant tachycardia

AV block following radiofrequency (RF) ablation for the treatment of atrioventricular nodal reentrant tachycardia (AVNRT) is a rare but well recognised complication of the procedure. The purpose of the study was to report the long-term follow-up of patients a first d (AVB1), second d (AVB2), or third d A V block (AVB3) occurred during ablation of AVNRT.Methods930 patients, 615 females, aged from 12 to 92 years, mean age 52±18, had AVNRT. RF energy, 65°, 40 watts was delivered on the slow pathway, until AVNRT was not induced.Results94 patients presented a transitory or permanent AVB1,2,3. In 8, mean age 53±21.5 years, AVB was of vagal origin generally occurring at femoral puncture (group I). In 26 patients, mean age 46±21, it was traumatic and regressive occurring either in young patients with a normal conduction system or in 3 patients with a left bundle branch block. In remaining 60 patients, AVB was directly related to the RF application; AVB was of first degree in 22 patients aged 56±17 years; it was of 2nd or third degree AVB in 38 patients: in 2 patients AVB3 remained permanent and in all other patients it was partially or totally regressive. After a follow-up of 2.1±2 years, pacemaker implantation was implanted in 15 patients, 1 patient with traumatic AVB3 aged 81 years, 5 patients with AVB3 during ablation, 2 with permanent AVB3 (0.2%) and 3 with transitory AVB3 and 9 patients without AVB during ablation. In these last patients, 2 had spontaneous long HV interval. Age of these patients differed from age of patients with RF-related AVB (73±14 vs 56±17) (p< 0.04). 5 patients with transitory AVB3 remained symptomatic with alternating slow junctional rhythm and sinus tachycardia.ConclusionsAVB remains frequent during AVNRT ablation (10%) but it is frequently benign and not directly related to the RF application. Permanent complete AVB is exceptional (0.2%). Patients with transitory complete AVB remain at high risk of later events as conduction disturbances or sinus tachycardia. Other AVB’s are age-related and probably without relation with ablation. Permanent or transitory 1 degree AVB seems without clinical significance