Electroanatomic properties of pulmonary vein antral regions enclosed by encircling ablation lesions.

AIMS Encircling ablation of the right and left pulmonary venous antra is commonly practiced. The importance to procedure outcome of electrical isolation of unablated myocardium enclosed by the encircling lesions is increasingly clear. The safe and effective achievement of isolation is dependent on a thorough comprehension of the 'electroanatomic' ablation substrate. We sought to improve comprehension of this substrate by examining relationships between anatomy and electrogram amplitude and timing after encircling ablation. METHODS AND RESULTS After deployment of encircling antral ablation lesions, detailed, echocardiographically guided mapping of endocardial regions enclosed by the lesions was performed. Among patients in whom the encircling lesion did not produce electrical isolation of the enclosed region (143 of 199 left antra and 37 of 198 right antra), separate electrograms generated by enclosed atrial myocardium (EM) and contiguous non-enclosed myocardium (NEM) were apparent at most mapped sites. Non-enclosed myocardium electrogram amplitudes demonstrated a spatial pattern which could be understood by considering contiguous atrial anatomy. Enclosed myocardium electrogram amplitudes demonstrated distinct spatial patterns that were more variable and not related to contiguous anatomy; they guided one or more additional ablation lesions within the enclosed region, which produced isolation. Among patients in whom the encircling lesion did produce isolation of the enclosed region, only NEM electrograms were consistently observed. CONCLUSION The relationships between anatomy and electrogram amplitude and timing detailed herein may be helpful during the conduct of encircling ablation with a goal of isolation of EM.