Fibroblasts, Focal Triggers, and Persistent Atrial Fibrillation

Abstract

Ablation of persistent atrial fibrillation (AF) remains challenging, particularly as the duration of continuous AF before the procedure increases. Attainment of durable pulmonary vein (PV) isolation remains a fundamental goal in this population; continuous retriggering from focal peri-PV sources (both automaticity and localized reentry) as a potential mechanism for maintaining persistent AF was documented more than a decade ago.1 An area of continuing debate centers on the extent of additional atrial ablation outside the PV antra required for long-term maintenance of sinus rhythm. Two studies published in this issue of Circulation: Arrhythmia and Electrophysiology highlight important clinical aspects of this debate. Articles see p 287, 295, and 442 Inoue and colleagues2 report long-term follow-up of catheter ablation in 263 patients with persistent AF (mean duration of continuous AF, 11 months; >1 year in 50%). To identify triggers that may perpetuate AF, cardioversion was performed at procedure onset, followed by short-duration isoproterenol infusion if needed, to provoke immediate recurrence of AF. The immediate recurrence of AF occurred in 70 (27%) of 263 patients, one third arising from non-PV foci. These triggers were then targeted for ablation (successful in all peri-PV foci, but in only 6 of 23 patients with non-PV triggers). All patients subsequently underwent PV isolation, and 72% had additional non-PV left atrial ablation. At the last follow-up of 17 months (38% of patients receiving antiarrhythmic drugs [AADs], multiple procedures in ≈30%), 90% of patients were in sinus rhythm, although 16% continued to have paroxysmal episodes. Immediate recurrence of AF was associated with a greater risk of recurrent persistent AF during follow-up, predominantly a result of inability to localize and eliminate non-PV focal triggers. In a randomized trial of ablation for persistent AF, Dixit and coworkers3 evaluate 3 strategies for ablation of persistent AF: (1) …