The ALICIA-FA study will elucidate whether targeting atrial myocardial fibrosis identified by late gadolinium-enhanced magnetic resonance imaging (LGE-MRI) improves atrial fibrillation (AF) ablation outcomes.

Atrial fibrosis is a hallmark of the AF substrate. An accurate identification and localization of myocardial fibrosis areas prior to an ablation procedure by means of LGE-MRI might help to target atrial areas harboring AF, thereby improving ablation outcomes and reducing AF recurrences.

In order to test this hypothesis, we will conduct a randomized study comparing the isolation of pulmonary veins without fibrosis imaging (conventional ablation procedure) vs. isolation of the pulmonary veins and pathological (fibrotic) tissue with the aid of LGE-MRI. Fibrotic tissue patches will be encircled and isolated in all patients in the active arm; furthermore, LGE-MRI will be used to identify, locate and guide ablation catheter to anatomical gaps surrounding pulmonary veins in re-do procedures.

Eventually, we will identify an optimized ablation strategy in patients undergoing AF radiofrequency ablation on the basis of left atrium (LA) fibrosis characterization.

Inclusion Criteria:

• Patients undergoing a first or subsequent ablation procedure.
• Pre-procedural 3 Tesla LGE-MRI.
• Referred for radiofrequency ablation of pulmonary veins (paroxysmal, persistent or long-standing AF).
• Signed informed consent.

Exclusion Criteria:

• Claustrophobia.
• Refusal to participate in the study.
• Presence of atrial thrombus.
• LA anteroposterior diameter >55 mm.
• Major renal impairment.
• Contrast allergy.
• Pregnancy.