Linear lesions alter organization of atrial fibrillation

Linear ablation lesions reduce the inducibility of atrial fibrillation (AF) in dogs. To test if organization of AF increases after ablation, magnitude-squared coherence was measured before and after circumscribing the right atrial appendage (RAA) with a linear radio-frequency ablation lesion. In 5 open-chest dogs, an 8/spl times/14 array of unipolar electrodes (2/spl times/4 cm) mapped the epicardium of the right atrial free wall during AF. Coherence, which is bounded from 0 to 1, was measured over 4 sec intervals. A site at the base of the RAA near the lesion (Ref 1) and a site approximately 1.5 cm distant to the lesion (Ref 2) were chosen. For Ref 1, average coherence increased by 0.084/spl plusmn/0.036 (p<0.007). For Ref 2, average coherence increased by 0.029/spl plusmn/0.036 (p<0.15). Changes in coherence are significantly greater near the lesion as compared to that more distant to the lesion. A sufficient number of linear lesions may reduce the inducibility of AF by increasing its spatial organization.