Background: Catheter ablation procedures for atrial fibrillation (AF) often involve circumferential pulmonary vein isolation (PVI). Lack of reliable identification of conduction gaps along the ablation line necessitates additional ablation within previous lesion sets. We conducted a retrospective comparative study to determine the best PVI strategy for prevention of PV reconnections.
Methods and results: We compared the outcomes of PVI performed in two groups of patients with AF: those in whom a three-dimensional mapping system and irrigated tip radiofrequency catheter were used to electrically isolate the ipsilateral PVs (31 patients, electrical isolation group) and those in whom "pace and ablate" was performed in the PV antra until pacing at 10 mA and 2 ms no longer captured the atrial myocardium along the ablation line (31 patients, pace and ablate group). A bolus administration of 30 mg of adenosine triphosphate (ATP) revealed dormant PV reconnections more frequently in the electrical isolation group than in the pace and ablate group (28 [90%] of 31 patients vs. 16 [52%] of 31 patients, p = 0.0005). After re-isolation of the sites of dormant PV conduction, the post-ablation recurrence rates at 1 year were similar (26 vs. 26%, p = 1.000).
Conclusion: Electrical PVI can usually be achieved without complete circumferential ablation. However, the isolated PVs often show dormant conduction. These findings support the hypothesis that reversible tissue injury contributes to PVI that may be acute but not necessarily durable. Similar outcomes between the two ablation strategies suggest that ATP provocation tests remain necessary to unmask dormant PV conduction.