MRI based injury characterization immediately following ablation of atrial fibrillation

A major limitation of catheter ablation for atrial fibrillation is the lack of tools to evaluate the efficacy and extent of lesion creation. Late gadolinium enhanced MRI has been used to detect acute injury following ablation, and scar tissue that forms weeks to months later. However, at the earliest imaging time point previously feasible in a clinical setting (< 24 hrs. post-ablation) the tissue hyper-enhancement was diffuse and poorly predictive of future scarring. Using a new EP/MRI facility, and images acquired approximately 1 hr. post-ablation, heterogeneous atrial wall enhancement was observed. Specifically, regions of hypo-,normal, and hyper-enhancement were detected. Quantitative comparison of hyper-enhancing scar at 3 months post-ablation to enhancement states imaged acutely indicated a significant majority of scar comes from hypo-enhancing tissue. Further study of hypo-enhancing tissue may facilitate early examination of procedural end-points and prediction of scar formation.