Abstract 21249: MRI Characterization of Tissue Injury Progression After Atrial Fibrillaton Ablation
Introduction: Characterization of ablation lesion could help guide procedures by identifying viable tissue and scar gaps. In this study we showed MRI characterization of atrial tissue injury progression from catheter touch down to three months post ablation.
Methods: Fifty patients underwent AF ablation under electro-anatomical guidance. Each patient was taken to a 3T MRI scanner immediately after ablation. High resolution LGE-MRI images of the left atrium (LA) were acquired 15 minutes after contrast injection. In addition, ten pigs were ablated in a 3T real-time MRI suite during scanning and T2 weighted and LGE-MRI images obtained during and immediately post-ablation respectively.
Results: T2w HASTE images showed enhancement during ablation, initially in the area of RF delivery followed by spatial extension beyond this area. T2w enhancement was seen as early as 10–15 seconds post ablation. LGE-MRI imaging immediately post ablation often showed dark, non-enhancing regions of ablated tissue (Figure 3, A1-A3). These non-enhancing regions were seen along with enhancing regions and imply different, but definite, tissue injury in the acute setting. These dark, non-enhancing regions showed enhancement three months later confirming scar formation (Figure 4, B1-B3). Mixed LA tissue injury is also seen on a gross pathology specimen from a pig immediately after ablation (Figure 3) and 3D reconstructions from LGE-MRI images (MAREK custom software) demonstrates long term prediction of scar formation of these non-enhancing areas (figure 2).
Conclusions: Enhancement at 20 seconds on T2w images on RT-MRI during ablation correlated well with lesion size ex-vivo. Non-enhanced ablated tissue may represent a no-reflow phenomenon or hemorrhage and appears predictive of late scarring (Figure 1). These findings may be useful in predicting tissue injury caused by RF energy and scar formation; and could be used to determine MRI based end-points to AF ablations.
- © 2010 by American Heart Association, Inc.