Evaluation of cryoballoon pulmonary vein isolation lesions during the acute and chronic phases using a high-resolution mapping system

Background An acute cryothermal ablation lesion contains both reversible and irreversible elements. However, differences in lesions created with cryoballoon pulmonary vein isolation (PVI) between the acute and chronic phases have not been fully elucidated. Methods We retrospectively analyzed 23 consecutive patients with atrial fibrillation who underwent cryoballoon PVI during the initial procedure followed by a second ablation procedure. In all patients, cryoballoon PVI lesions were evaluated with high-resolution voltage mapping just after PVI (acute phase) and during the second session (chronic phase). We compared the area and width of the non-isolated left atrial posterior wall (NI-LAPW) with voltage ≥ 0.5 mV during both sessions. Results PVI was successfully achieved in all patients. Cryoballoon PVI lesions were re-evaluated at 11 [2–17] months post-procedure. During the chronic phase, NI-LAPW width became significantly larger at the level of the roof (change, 5.8 ± 5.5 mm; p < 0.001) and at the level of the carina (change, 3.3 ± 7.0 mm; p < 0.05), and NI-LAPW area became significantly larger (change, 1.5 ± 1.9 cm 2 ; p < 0.001) compared with the acute phase. Eight patients without any PV reconnections also had larger NI-LAPW areas (change, 1.3 ± 1.2 cm 2 ; p < 0.05) during the chronic phase. Conduction resumption confined to the right carina was observed in 1 (4.3%) patient who presented with circumferential PVI that included the carina during the first session. Conclusion Acute cryoballoon PVI lesions significantly regressed during the chronic phase. PV reconnections and the isolation area should be carefully re-evaluated during the second procedure.