Background: Few reports exist regarding the details of ice formation on second-generation cryoballoon (CB) surface during pulmonary vein isolation (PVI). We propose a new parameter "temperature drop" in thawing phase for predicting sufficient ice formation and CB-PVI outcome.
Methods: Consecutive 106 patients who underwent successful CB-PVI for atrial fibrillation (AF) were analyzed. We defined "temperature drop" as a temperature drop of more than 3 °C just after CB catheter bending. We compared the previously known parameters predicting durable PVI between PVs with or without temperature drop. Then, we compared the PVI outcome among three groups: group 1 with temperature drop in all PVs, group 2 with temperature drop in 1-3 PVs, and group 3 without temperature drop in any PV.
Results: Temperature drop was present in 206 out of 424 isolated PVs. In those, PV occlusion score was significantly higher (3.7 ± 0.5 vs. 3.5 ± 0.6, P <0.001), and thawing time was significantly longer (55 ± 20 vs. 46 ± 21 s, P < 0.001) in PVs with temperature drop than those without. With a mean follow up period of 376 ± 217 days, Kaplan-Meier survival analysis revealed that no patients in group 1 experienced AF recurrence, 14 out of 86 patients (16%) experienced AF recurrence in group 2, and 5 out of 10 (50%) patients experienced AF recurrence in group 3 (Log-Rank P = 0.003).
Conclusion: The temperature drop in thawing phase might reflect the state of ice formation and can be used to predict clinical outcome after CB-PVI.
Keywords: Atrial fibrillation; Cryoballoon pulmonary vein isolation; Temperature profile.