Usefulness of Paced Activation Sequence Mapping in Catheter Ablation of Accessory Pathways

INTRODUCTION: Radiofrequency (RF) ablation of accessory pathways (APs) is often a time-consuming procedure, mainly because conventional criteria have modest accuracy. Thus, additional mapping criteria are desirable. Our hypothesis was that comparison of paced atrial activation sequences with that obtained during orthodromic AV reentrant tachycardia might be useful for locating the atrial insertion of single APs. METHODS AND RESULTS: The study included 15 patients with a single AP referred for ablation. Analysis of the atrial activation sequence was simplified by measuring the activation time (AT) that elapsed between two atrial reference points placed next to the AV annulus on either side of the area containing the AP. Ablation was guided by conventional criteria. Before each RF delivery, a short pacing train was delivered from the ablation catheter and, after verification of atrial capture, the AT was compared with the AT obtained during orthodromic tachycardia. Fifty sites of RF delivery were appropriate for analysis. The multivariate model with the highest predictive power included a deviation of AT between pacing and tachycardia < or = 5 msec (P < 0.001), a local AV ratio > or = 1 (P = 0.04), and stability of the local electrogram (P = 0.05). The combination of all these criteria predicted a successful application with high sensitivity, specificity, and positive predictive value (92%, 86%, and 71% respectively). To validate the method prospectively, 10 additional consecutive patients underwent an AP ablation procedure guided by these criteria. CONCLUSION: This technique seems to be highly accurate in selecting the atrial site for RF ablation of single APs.