LGE-MRI Characterization of Left Atrial Fibrosis: a Tool to Establish Prognosis and Guide Atrial Fibrillation Ablation

Abstract

Atrial fibrillation (AF) is the most frequent arrhythmia and also an important cause of morbidity, hospitalization, and mortality. Pulmonary vein isolation (PVI) is often the preferred therapy, but the incidence of recurrences is still significant. This review summarizes the contribution of atrial substrate identification using late gadolinium enhancement magnetic resonance imaging (LGE-MRI) to establish prognosis and to guide AF ablation. Left atrial (LA) fibrosis is thought to create the necessary substrate to sustain AF. The accuracy of LGE-MRI to identify areas of atrial fibrosis remains controversial. However, the amount of LA fibrosis visible in the 3D reconstruction of LGE-MRI has been identified as a sign for AF progression and poor outcome after ablation. Additionally, the scar created by radiofrequency and cryoablation lesions can be visualized after the procedures. Discontinuities in PVI ablation lines have been related to recurrence and can be used to identify electrical reconnections. Ongoing research is directed toward validating fibrosis ablation as a new target to improve ablation outcomes. Atrial fibrosis assessment by LGE-MRI may show the severity of atrial disease and could be used to select patients likely to benefit the most from AF ablation. Usefulness of an individually tailored LGE-MRI-guided ablation approach is still under evaluation.