In recent years, radiofrequency catheter ablation has evolved into an effective treatment modality for many patients with atrial fibrillation (AF). Although compartmentalization of the atria using surgical techniques (MAZE procedure) has long been demonstrated to be effective in eliminating AF, this approach is complex and technically challenging (1,2). Therefore, it is not easily adaptable to the clinical electrophysiology laboratory.

A key step that accelerated the efforts to eliminate AF has been the observation that arrhythmogenic foci within the pulmonary veins (PVs) can initiate AF, and that elimination of such foci may result in maintenance of sinus rhythm in some patients with AF (3, 4, 5, 6). As the role of the PV antrum in AF became better understood (7), ablation strategies evolved to also target the PV antrum in addition to the PVs using a variety of techniques, including extraostial PV isolation, circumferential PV ablation, left atrial circumferential ablation, wide-area circumferential ablation, and PV antrum isolation (7, 8, 9, 10, 11, 12). In addition to ablation within the antrum, these ablation strategies also involved either complete electrical isolation of the PVs or elimination of PV tachycardias (with entrance block into the PV) without necessarily isolating the PVs (13, 14, 15).

The mechanisms of AF are multifactorial (16). Among these mechanisms are: PV arrhythmogenicity, which may be observed as isolated or nonsustained premature depolarizations or repetitive bursts of PV tachycardias; multiple wavelet reentry; high-frequency sources due to anisotropic re-entry (rotors); and modulations in the autonomic innervation of the atria (3,14,15,17, 18, 19). Some or all of these mechanisms may be eliminated by wide-area antral ablation plus PV isolation, resulting in success rates of 70% to 95% for both paroxysmal and chronic AF (5, 6, 7, 8, 9, 10, 11, 12,20, 21, 22).

Because the mechanisms of AF are multifactorial and may not be the same in all patients with AF, targeting PVs and the antrum empirically may not necessarily eliminate all potential mechanisms of AF and may also lead to unnecessary applications of radiofrequency energy at sites not critical to the perpetuation of AF. This is the rationale for a tailored ablation strategy to eliminate AF (23).