Delayed Enhancement Assessment of Pulmonary Veins Using 3 Tesla Magnetic Resonance Imaging after Atrial Fibrillation Ablation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice. Epidemiological data show that AF is associated with significant morbidity and mortality, resulting in high medical and hospital costs.1 The dismay generated by the modest impact of antiarrhythmic agents in the natural history of AF motivated the development of non-pharmacological methods aimed at curative treatment of this arrhythmia. In this context, over the past decade, catheter ablation with percutaneous techniques evolved considerably and has become a therapeutic option for selected patients with AF.2 Imaging methods, such as intracardiac echocardiography and electroanatomic mapping have been increasingly incorporated to increase the efficiency and safety of the method. The efficiency of ablation has been discussed in recent years to evidence factors that contribute to the recurrence rates of AF. Failure of the procedure is often attributed to resumed conduction between the pulmonary veins and the left atrium due to incomplete ablation of ectopic foci.3 Cardiac magnetic resonance (CMR) with delayed enhancement technique is a noninvasive imaging modality used to view areas of fibrosis. In the context of AF, it may be adapted to identify fibrosis induced by radiofrequency waves on the left atrial wall and in the pulmonary vein ostia after ablation of AF. The fibrotic regions present increased signal intensity on delayed enhancement due to the slow gadolinium washout in the injured tissue. In this scenario, initial studies suggest that CMR with evaluation of atrial fibrosis using the delayed enhancement technique can provide important information about the radiofrequency ablation sites, potentially identifying incomplete isolations and preexisting areas of atrial fibrosis that may result in a higher AF recurrence rate after the procedure.4