Abstract 14452: Complex Fractionated Atrial Electrograms Represent Areas of Normal Voltage in Patients With Persistent Atrial Fibrillation: Implications For Ablation

Background: Pulmonary vein isolation (PVI) followed by adjunctive complex fractionated atrial electrograms (CFAE) ablation is thought to be associated with increased freedom from persistent atrial fibrillation (AF) after a single procedure. Although CFAE are purported to represent critical sites for AF perpetuation, there are conflicting studies suggesting that CFAE may represent sites of passive wavefront collision, which are not important to the maintenance of AF. Hence, the underlying electroanatomic mechanism of CFAE remains poorly defined. This study evaluated the relationship between CFAE and areas of abnormal atrial tissue defined by low voltage electrograms (LVE). Methods: 14 patients, with persistent AF were studied prospectively. CFAE maps were obtained after PVI during persistent AF. Patients were then cardioverted into sinus rhythm and a new voltage map was acquired in sinus. Abnormal LVE were defined as Results: All patients had substantial CFAEs that accounted for 33.11 ± 24% of total left atrium (LA). In sinus rhythm, only 12.26 ± 10 % of LA area had LVE. There was no anatomic correlation between CFAE sites and LVE; the area of overlap between CFAE and LVE was only 1.59 ± 1.5. Conduction was faster in CFAE areas (2.27±1.35m/sec) than in normal voltage areas (1.27±0.29m/sec) LVE areas (1.11±0.69m/sec, p=0.0675). There was no correlation between the % of CFAE areas and parameters of SAPW; whereas there was a positive correlation between LVE areas and SAPW (r= 0.691, p= 0.043). Conlusions: Our study suggest the following: 1) Areas of CFAE detected during AF correspond to areas of normal atrial voltage and normal conduction velocity during NSR; 2) The SAPW duration is a good non-invasive index of scarred atrial substrate as suggested by its good correlation with intra-atrial left atrial LVE. 3) CFAE probably represent the response of normal healthy atrial tissue with short refractory periods and normal conduction velocity to rapid PV firing rather than abnormal scarred atrial myocardium.