Po-04-109 outcomes of radiofrequency catheter ablation of distinct antero-septal accessory pathways by conventional electrophysiological mapping

Ablation of para-hisian accessory pathways (APs) is challenging because of their proximity to the conduction system. A high incidence of atrio-ventricular (AV) conduction injury (up to 50%) was observed for the ablation of true para-hisian APs. In this retrospective study, we report the outcomes of a large series of patients with antero-septal APs (including true para-hisian APs) who underwent radiofrequency catheter ablation (RFCA). Among 1676 consecutive patients undergoing RFCA of APs between January 2016 and September 2022 in our center, 276 patients with an isolated antero-septal AP were enrolled. Conventional intracardiac mapping and fluoroscopy were used in all procedures. All procedures were performed by an experienced operator with a standard 3.5 mm irrigated tip catheter. A para-hisian AP was confirmed when an His potential was recorded by the distal ablation catheter at the site of earliest atrial activation during orthodromic AVRT or after ablation of the manifest AP. APs were categorized as true para-hisian if a sharp high-amplitude His potential was recorded. Among the 276 patients (mean age 27±10 years; 150 males) with an antero-septal AP: 55 patients (20%) had a true para-hisian AP (Group 1); 89 patients (32%) had a not-sharp low-amplitude His potential (Group 2); 132 patients (48%) had no His potential recorded (Group 3). The three Groups showed no significant difference in clinical (age, sex, history of AF and AVRT, structural heart disease) and EPS variables (conduction properties of APs and inducibility of AVRT and AF). Inferior vena cava (n=260) and aortic retrograde (n=16, targeting the left basal septum) approaches were used. Procedural acute success (no evidence of residual preexcitation or abnormal retrograde conduction) was obtained in all patients. No patient experienced acute severe complications. RF ablation time was longer in Group 1 (135±41 sec vs 115±27 sec [Group 2] vs 92 sec ±18 sec [Group 3], p=0.03). Accelerated junctional rhythm during RFCA was more frequent in Group 1 (25% vs 14% [Group 2] vs 3% [Group 3], p=0.02). After a median follow-up of 40 (2-78) months no high-grade AV block was reported. 1 patient of Group 1 had a recurrent para-hisian AP and underwent a second successful RFCA. In this large series of antero-septal APs (including a high number of true para-hisian APs), electrophysiologically-guided RFCA was safe and highly effective.