The aim of the LATE (multidetector CT Lefi Appendage atrial Thrombosis Exclusion in patients with atrial fibrillation) study is to evaluate the diagnostic accuracy of cardiac Computed Tomography (TC) with 64 detectors and double acquisition phase in candidate patients ablation of atrial fibrillation (AF) with the Navx (or Carto) technique, using trans-esophageal ultrasound (TEE) as the standard reference.

This study is based on the use of an experimental protocol in cardiac TC which involves, in addition to the acquisition of an early arterial phase (standard protocol routinely performed in all patients), the execution of a possible late phase at a very low dose of radiation (experimental protocol) aimed at increasing the accuracy of the method in the diagnosis in patients with AF. The LATE study aims to demonstrate the high diagnostic accuracy of dual acquisition phase cardiac TC in the diagnosis of intraauricular thrombosis by comparing it with reference standard; in light of this result, cardiac TC could constitute a single non-invasive diagnostic tool in the future for the global evaluation of both atrial anatomy and endoawicular thrombosis with a clear improvement in patient management both in clinical and economic terms.

Inclusion Criteria:

• patients candidates for cardiac TC and transesophageal ultrasound examination for the evaluation of cardiac anatomy and for the exclusion of intra-auricular thrombosis.

Exclusion Criteria:

• < 18 years patients

Patients in whom there is a doubt of thrombosis in the early arterial phase.