Abstract 4144751: Relationship between abnormal conduction area detected by isochronal late activation mapping in sinus rhythm and arrhythmogenicity of atrial fibrillation

Background: The arrhythmogenic substrate in atrial myocardium could contribute the trigger of atrial fibrillation (AF) except pulmonary vein (PV). This study was conducted to investigate the arrhythmogenic substrate using an isochronal late activation mapping (ILAM) related with the trigger of AF. Methods: Forty-five AF patients (age 65±9 years old,35 Males,17 non-paroxysmal AF,11 patients with 2 nd -session procedure) who underwent the catheter ablation for AF were enrolled. The high-density activation mapping of left atrium (LA) was obtained by in sinus rhythm or atrial pacing with a cycle length of 600ms. ILAM was retrospectively constructed and deceleration zone was defined as abnormal conduction area with ≥3 isochrones within a 1cm radius along with a discontinuity of conduction zone. Relationship between the AF arrhythmogenicity and ILAM deceleration zone was investigated. Results: Patients with non-paroxysmal AF has larger number of ILAM deceleration zone in LA than those with paroxysmal AF (median [interquartile], 4.0[2.5-7.5] vs.0[0-5], p=0.028). Of all, 15 patients had a trigger of AF except pulmonary vein (non-PV foci) in the LA (10: posterior wall, 6: anterior wall, 2: septum, 1: roof). Patients with non-PV foci had a larger number of ILAM deceleration zone in LA than those without (median [interquartile], 6.0[4.0-8.0] vs.0[0-4], p<0.001). Furthermore, 15 patients with non-PV foci had 35 deceleration zones in sinus rhythm, 26 of them were associated with non-PV foci. On the other hand, of total 87 deceleration zones in all patients, 61 deceleration zones had no contribution to the non-PV foci. Conclusion: ILAM deceleration zone with ≥3 isochrones within a 1cm radius along with a discontinuity of conduction zone obtained in sinus rhythm may be useful to assess the atrial myocardial arrhythmogenic substrate related with non-PV foci.