Junctional rhythm during slow pathway radiofrequency ablation in patients with atrioventricular nodal reentrant tachycardia: Beat-to-beat analysis and its prognostic value in relation to electrophysiologic and anatomic parameters

Junctional Rhythm and Slow Pathway Ablation. Introduction: Junctional rhyth m usually is considered a sensitive but nonspecific marker of successful ab lation of the slow pathway in AV nodal reentrant tachycardia. Nevertheless, this junctional rhythm has been little studied, and its relations to recog nized predictors of successful radiofrequency (RF) application were never e stablished in any study. Methods and Results: Thirty-nine patients underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia. Ninety RF applications were de livered, and each ablation site was determined using three different fluoro scopic projections. Six anatomic zones were defined from low posterior sept um to the site of distal His-bundle recording (P1, P2, M1, M2, A1, and A2). Characteristics of junctional rhythm during RF applications were analyzed. Atrial electrogram characteristics at the ablation sites also mere studied . All patients had successful slow pathway ablation, without any complicati on. The ablation sites were located as follows: 41 at P1, 26 at P2, 20 at M 1, and 3 in M2. Forty RF applications were successful: 14 of 41 attempts at P1, 7 of 26 at P2, 16 of 20 at M1, and 3 of 3 at M2. Mid-septal ablation s ite (M1 and M2) was associated with higher occurrence of junctional rhythm (P < 0.0001), earlier first junctional beat (P = 0.008), and earlier occurr ence of the longest junctional burst (P = 0.03) compared with posterior abl ation site (P1 and P2). The combination of a mid-septal ablation site and a first junctional beat occurring less than or equal to 3 seconds after onse t of RF application identified successful RF application with 100% accuracy . Using multivariate analysis, the ablation site, duration of atrial electr ogram (including slow pathway potential when present), and occurrence of ju nctional rhythm were independent predictors of success. Conclusion: Successful slow pathway ablation depends on many factors. Junct ional rhythm characteristics are related to the site of RF delivery and can be helpful in assessing successful slow pathway ablation.