Requirement of larger local impedance reduction for successful lesion formation at carinal area during pulmonary vein isolation

Purpose Local impedance (LI) measurement from an ablation catheter is useful in predicting lesion size and acute success of pulmonary vein isolation (PVI). The LI variation can be described by absolute LI drop (Delta LID) or Delta LID/initial LI (%LID). We evaluated the utility of these parameters in predicting acute lesion durability during PVI using a novel catheter capable of measuring both LI and contact force (CF). Methods PVI with a targeted CF, power, and duration was performed in 23 consecutive patients with paroxysmal atrial fibrillation. LI was blinded to operators during ablation. Parameters for each RF application were collected and compared for acute successful lesions and gaps. Results A total of 1633 RF applications including 97 (5.9%) gap lesions were analyzed. Successful lesions were more frequently observed at non-carinal sites and those with higher contact force, FTI, initial LI, and larger variation of LI and generator impedance (GI). Multivariate analysis demonstrated that absolute GI drop (Delta GID) [OR 1.09 (1.04-1.15), p < 0.001], Delta LID [1.12 (1.09-1.16), p < 0.001], Delta GID/initial GI (%GID) [OR 1.04 (1.01-1.07), p = 0.01], and %LID [OR 1.15 (1.12-1.28), p < 0.001] were significantly associated with successful lesions, and carinal site [OR 0.15(0.09-0.24), p < 0.001] was significantly related to gaps. Both Delta LID and %LID equally predicted the acute durability of lesions during PVI. Delta LID >= 24 Omega and %LID >= 15% at the carina, and Delta LID >= 21 Omega and %LID >= 14% at non-carinal sites significantly predicted acute successful lesions with negative predictive values of 93-99%. Conclusions Both Delta LID and %LID were equally useful in predicting acute successful lesions during PVI. Larger cut-off values should be applied to carinal sites.