A Novel Annotation Technique During Mapping to Facilitate the Termination of Atrial Tachycardia Following Ablation for Atrial Fibrillation

INTRODUCTION: The treatment of atrial tachycardia (AT) occurring after ablation for atrial fibrillation (AF) is challenging. The most common ablation strategy relies on entrainment, and electroanatomic activation mapping (EAM) using a conventional window of interest (WOI), centered on the easily detectable atrial signal on the coronary sinus catheter. We describe a novel EAM annotation technique that uses a WOI starting 40 milliseconds prior to the P wave in order to detect the reentrant AT exit site. This WOI timing is based on the similarity between scar-related reentrant AT and scar-related ventricular tachycardia. METHODS: Patients with AT after prior ablation for AF were included. The EAM of the AT was performed using the novel mapping annotation technique. The ablation was considered successful if the AT terminated during ablation at the site identified by this strategy. RESULTS: Twenty-eight patients with 36 ATs were included. The ATs were classified as follows: mitral annulus (13/36), roof (11/36), anterior/posterior/lateral left atrial wall (10/36), and RA (2/36). A complete EAM using the novel annotation technique was achieved in 34 of 36 AT's, encompassing 94 ± 6.5% of the cycle length. Low amplitude pre-P fractionated electrograms were found in 34 of 36 (94%) ATs and these occurred at a mean distance of 1.8 ± 1.2 mm from the "early-meets-late" line. Ablation at these areas resulted in termination of 34 of 36 ATs (94%). CONCLUSION: The novel EAM annotation allows the accurate detection of the critical isthmus of post-AF ablation AT. Ablation of these isthmuses results in termination of the AT in the vast majority of patients.