Andrea Di Cori is Medical Doctor in the Cardiac and Toracic Department at the Santa Chiara hospital in Pisa. Dr Di Cori’s research project title is Cardiac CT With Delayed Enhancement in the Characterization of Atrial Arrhythmias Structural Substrate: Relationship Between CT-Segmented Scar and Electro-Anatomic Mapping. Aim of the study is to determine the impact of Computed Tomography with delayed enhancement (CTDE) in the pre-procedural assessment of left atrial (LA) substrate of patients with persistent atrial fibrillation (AF) or persistent atrial flutter (AFl) candidated to radiofrequency ablation (RFA).