The feasibility and safety of substrate modification on the left atrial roof area using a cryoballoon in atrial fibrillation ablation

•The CB roof ablation following the CB-PVI resulted in a high arrhythmia freedom regardless of the AF type.•A lower balloon temperature during the CB roof ablation was associated with a continuous LA roof scar during the acute phase.•Electrical conduction block across the roof line was proven in 25% of the patients during the chronic phase and the remaining 75% patients had an incomplete roof line block.•An iatrogenic roof dependent AT, takotsubo cardiomyopathy, and severe pericarditis were the major complications after the procedure.