The electrical characteristics and clinical significance of the effect of adenosine on dissociated activity after circumferential venous isolation in patients with atrial fibrillation

Background: Dissociated activity can occur after circumferential thoracic vein isolation for treating atrial fibrillation (AF). However, its clinical significance and response to adenosine remain unclear. Methods: Fifty-three patients (10 women, 11 with non-paroxysmal AF, with mean age 54.4 ± 11.2 years) with slow dissociated activity after thoracic vein isolation for AF ablation were analyzed. Adenosine (12 mg) was injected intravenously into 30 patients, and the responses of the dissociated activities were recorded. Results: The clinical characteristics and the rate of recurrence did not differ between patients with and without dissociated activity. Dissociated activity was most frequently observed at the right superior pulmonary vein (PV) (61%), left superior PV (26%), right inferior PV (5%), left inferior PV (4%), and non-PV sites (4%). The locations of dissociated activities were associated with the AF trigger sites (p = 0.004). Adenosine injection decreased the cycle length of dissociated activity in 13 patients (group 1) and increased it in 17 patients (group 2). Dissociated activity disappeared in 7 patients (41%) (group 2) after adenosine injection. During the mean 33 ± 17 months of follow-up, group 2 patients had a lower AF recurrence rate (24%) than group 1 patients (62%) (p = 0.035). Conclusions: The locations of dissociated activity were closely associated with the AF trigger sites. The responses to adenosine may predict AF recurrence in patients with dissociated activity.