Objective: We present the case of a 69-year old female with no cardiovascular risk factors and a 4-year follow-up period in our institution. She presented in May 2014 for an 8-year history of persistent atrial fibrillati-on (AF), for which she underwent 3 electrical cardio-versions under high dose Amiodarone (400 mg/daily) because of severe symptoms.

Methods: Transthoracic echocardiography and CT exam revealed an enlarged left atrium (LA) (LA area 34 cm², LA volume/BSA 73 ml/m²) and normal EF. In July 2014 we performed PVI and CTI ablation with good clinical outcome. She remained free of symp-toms for the following 3 years under a small dose of beta-blocker, when she presented for the recurrence of ECG-documented paroxysmal AF episodes of hours-long duration. We planned a repeat procedure and a late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) evaluation was done beforehand. It de-tected dense fibrosis regions encircling all the PVs’ an-trum, fibrosis within the inferior aspect of the posterior LA and at the base of the LA appendage (LAA).

Results: As we expected, all PVs were isolated. During spontaneous rapid AF, we found complex fractiona-ted electrograms (CFAEs), which corresponded to the regions of fibrosis described on LGE-CMR. Radio-frequency ablation at these sites resulted in progressive conversion of the AF to persistent left atrial tachycardia with a cycle length of 600 ms. Activation mapping of the LA, localized the earliest atrial signal at the base of the LAA. Two radiofrequency application points at these sites terminated the tachycardia, resulting in re-storation of sinus rhythm (SR). Over the following 9 months, the patient maintained SR under no antiar-rhythmic drug therapy.

Conclusions: In our practice, we use frequently LGE-CMR to assess the extension of the fibrosis, especially in cases of persistent AF and repeat procedures. The-refore, the combination of CMR and CFAEs mapping could improve the outcome of the procedure and parti-cularizes the ablation technique for each patient.