C72 POSTERIOR WALL CHARACTERIZATION IN PATIENTS AFFECTED BY ATRIAL FIBRILLATION

Background Several clinical data in humans demonstrate that atrial fibrillation (AF) dominant frequencies and rotors are mostly localized on the posterior wall (PW), but the correlation among these phenomena and abnormal conduction properties during sinus (SR) and paced rhythm (PR) has never been analyzed. Aims. To provide a characterization of the left atrial PW in patients affected by persistent AF. In particular, the purpose is to describe the electrophysiological properties in terms of rotational and focal activities during AF, propagation uniformity during SR and functional sites definition during PR. Methods Six patients from two EP centers have been selected for this analysis. The clinical procedures have been performed with CARTO3 mapping system. All EGMs have been collected with Pentaray and Octaray catheters. For each patient, the module CARTOFINDER has been used during AF to identify areas with shorter and longer cycle length (site of conduction jump), rotational and focal activities; at least 15 areas have been collected in the PW. SR and PR map were performed after electrical cardioversion to exploit the functional phenomena. The paced map has been created by setting an extra beat from the coronary sinus every three sinus beats (pacing interval=local effective refractory period +40ms). Rotational and focal activities during AF have been identified and associated with signals collected during SR and PR. EGMs have been characterized in terms of voltage amplitude (mV), signal duration (ms) and fractionation. Results Abnormal areas of conduction recorded during AF were 33; at least one site of conduction jump was found in every patient, in most of the cases (77%, 10 out of 13) it was localized on the PW. 10 areas of focal activities have been found of which 7 (70%) were localized on the PW. Rotational activity has been found in 2 patients (in one on the PW). During SR and paced rhythm, at sites of interest, we found lower voltages (SR 1.9 ± 1,3mV, PR 1,7 ± 1,15mV), signal fragmentation and longer signal duration (SR 52,7 ± 8,85ms, PR 51,3 ± 11,04ms) compared to healthy tissue. Conclusion There is a strong correlation between sites of interest during AF and signal abnormalities recorded during SR and PR. This research work may pave the way to the study of abnormal conduction sites during SR which represent a relevant element for AF maintenance, providing a further step towards substrate characterization in patients affected by AF.