Clinical relevance of left atrial structural remodeling and non-pulmonary vein foci in atrial fibrillation.

Background: The mechanistic role of left atrial (LA) structural remodeling as a non-pulmonary vein (PV) trigger in the initiation of atrial fibrillation (AF) remains uncertain. This study is aimed at prospectively evaluating the association between non-PV triggers and LA structural remodeling.

Methods: A total of 517 patients undergoing catheter ablation for AF were included. After PV isolation, a standardized protocol was implemented to reveal non-PV triggers, which included burst pacing into AF followed by cardioversion during isoproterenol infusion. If pacing-induced atrial tachycardia (AT) was observed, mapping and catheter ablation were performed.

Results: The mean percentage of LA low-voltage area (LVA) < 0.5 mV incrementally increased during right atrial pacing among the no induction (n = 470), AF (n = 21), and AT (n = 26) groups (2.6 ± 5.7%, 5.5 ± 6.4%, and 18.0 ± 21.5%, respectively; P < 0.001). In the AF induction group, non-PV foci originated from the left atrium in 13 of 25 foci (52%), and 8 of 13 LA non-PV foci (62%) were located in the septal region. All except 1 focus originated from the non-LVA < 0.5 mV (8%), but 8 of the 13 LA foci originated from the LVA < 1.0 mV (62%). There were no differences in AF recurrence among the groups (log-rank, P = 0.160).

Conclusion: The majority of non-PV foci in the LA originated outside regions with advanced structural remodeling, thus suggesting the limited effectiveness of adjunctive ablation guided by the LVA < 0.5 mV during sinus rhythm in eliminating non-PV triggers.