Catheter Ablation -> Atrial Fibrillation & Atrial Flutter: -> Clinical Trials / Outcomes D-PO03 - Poster Session III (ID 48) Poster

D-PO03-146 - Local Impedance Drop During Pulmonary Vein Isolation Predicts Late Reconnection In Patients With Paroxysmal Atrial Fibrillation: Results Of The Localize Clinical Trial (ID 1123)


Background: Radiofrequency lesion efficacy is routinely monitored with generator impedance drop. Evaluation of a local impedance (LI) metric (DIRECTSENSE™, Boston Scientific) found LI drop to be highly predictive of effective lesion formation.
Objective: To evaluate whether LI drop during PVI is associated with late PV reconnection (PVr) in patients with paroxysmal AF.
Methods: The multicenter LOCALIZE trial consists of an index PVI procedure and a mandated 3-month follow-up mapping procedure. LA maps were created and ipsilateral PVs were divided into 8 segments. Point-by-point PVI, blinded to LI, was performed and residual gaps were ablated after a 20 min waiting period. At follow-up, late PVr sites were identified on electroanatomical maps. Median LI drop within each segment of the index procedure was calculated offline (Fig. Left).
Results: Forty-one de novo PVI and follow-up procedures were analyzed. At follow-up, blocked segments had significantly larger LI drops (19.2 [14.1-26.7] Ω) than segments with late PVr (12.5 [8.4-16.1] Ω, p<0.01, Fig. Right). In view of wall thickness differences, the association between LI drop and block was further evaluated for anterior/roof and posterior/inferior segments with inter-lesion distance ≤6mm. Anterior block segments had significantly larger LI drops (20.7 [15.9-28.1] Ω) than posterior block segments (16.0 [11.4-24.2] Ω, p<0.01). Optimal LI cut-off values were 17Ω in anterior segments and 14Ω posteriorly (positive predictive value for block: 98.8% and 98.4%, respectively).
Conclusion: With inter-lesion spacing of ≤6mm, reaching a LI drop of ≥17Ω anteriorly and ≥14Ω posteriorly was predictive of durable segment block in de novo PVI.