Can successful radiofrequency ablation of atrioventricular nodal reentrant tachycardia be predicted by pattern of junctional ectopy? Mohammad Hossein Nikoo, MD, Zahra Emkanjoo, MD, ⁎ Mohammad Vahid Jorat, MD, Ali Kharazi, MD, Abolfath Alizadeh, MD, Amir Farjam Fazelifar, Mohammad Ali Sadr-Ameli Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Research and Medical Center, Tehran, Iran Received 17 March 2007 Abstract Background: Emergence of junctional rhythm (JR) during radiofrequency (RF) current delivery directed at the periatrioventricular nodal region has been shown to be a marker of success in atrioventricular nodal reentrant tachycardia (AVNRT). Whereas the characteristics of JR during RF ablation of slow pathway have already been studied, the electrophysiologic features of different patterns of JR are yet to be evaluated. The aim of this study was to investigate in detail the characteristics of the JR that develops during the RF ablation of the slow pathway. Materials and Results: The study population consisted of 95 patients: 56 women and 33 men (mean age, 47.2 ± 16.3 years) who underwent slow pathway ablation because of AVNRT. A combined anatomical and electrogram mapping approach was used, and AVNRTwas successfully eliminated in all patients. This study identified 7 patterns for JR during the RF ablation of slow pathway: junction- junction-junction, sinus-junction-sinus, intermittent burst, sparse, no junction, sinus-junction- junction, and sinus-junction-block . The characteristics of JR, such as mean cycle length and total number, were gathered. The incidence of JR was significantly higher during effective applications of RF energy than during ineffective applications (P = .001). The mean number of junctional ectopy was 19.6 ± 19. The total number of junctional ectopy was significantly higher during effective applications of RF energy than during ineffective applications (24.6 ± 18.8 vs 8.4 ± 13.2; P b .001). We found a significant difference between the effective and ineffective applications of RF energy in the mean cycle length of the junctional ectopy (464.6 ± 167.5 vs 263.4 ± 250.2; P b .01). The patterns of JR were compared between effective and ineffective applications. We managed to show a significant correlation between patterns of JR and successful ablation (P = .01). Logistic regression analysis revealed that the presence of sinus-junction-sinus, sinus-junction- junction, and sinus-junction-block patterns of JR was a predictor of a successful RF ablation (confidence interval [CI], 1.67-15.92 [P b .004]; CI, 1.02-85.62 [P = .048]; and CI, 1.06-32.02 [P = .042], respectively). Conclusion: This study confirms that JR is often present during successful slow pathway ablation. The pattern of JR is useful as indicator of success. © 2008 Elsevier Inc. All rights reserved. Keywords: Junctional ectopy; Slow pathway; AVNRT; RF ablation Introduction Catheter-based slow pathway modification has become a first-line treatment of recurrent atrioventricular nodal reentrant tachycardia (AVNRT) with success rates approaching 100%. 1,2 Emergence of junctional rhythm (JR) during radio- frequency (RF) current delivery directed at the periatrioven- tricular (AV) nodal region has been shown to be a marker of successful catheter ablation in AVNRT and has been considered as a response of the AV node to the thermal injury of either the nodal or the perinodal tissue. 3-6 Available online at www.sciencedirect.com Journal of Electrocardiology 41 (2008) 39 – 43 www.jecgonline.com ⁎ Corresponding author. Tel.: +98 212391; fax: +98 2122055594. E-mail address: emkanjoo@rhc.ac.ir 0022-0736/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2007.07.005