Abstract 2746: Pre-ablation Assessment of Structural Remodeling in Atrial Fibrillation Helps Select Successful Ablation Strategy
Background: Different ablation strategies have been adopted in atrial fibrillation (AF) ablation with the common approach being pulmonary vein (PV) isolation. Most ablation experts agree that a more extensive lesion set is often required in some patients. We used delayed-enhancement MRI (DE-MRI) of the left atrium (LA) to study pre-ablation structural remodeling and determine the risk of recurrence using PV isolation with posterior and septal wall debulking as the ablation approach.
Methods: One hundred and forty-four patients underwent DE-MRI pre and 3 months after AF ablation. The left atrium (LA) was segmented out and volume rendered. A color map was applied to illuminate scar tissue. Pre and post ablation scar was quantified and reported as a proportion of the LA wall volume. Each PV antrum was analyzed for contiguous scar lesions, defined as no break or gap in the ablation lesion set. Patients’ clinical characteristics were obtained from clinic visits and chart reviews. Patients were followed up for 284±167 days. Recurrence was defined as 30 seconds of sustained atrial arrhythmia off anti-arrhythmic drugs after a 3 months blanking period.
Results: Pre-ablation enhancement was quantified in 113 of 144 patients (79%). Fifty five patients had mild (< 15% of LA tissue) enhancement, 46 had moderate (15–35%) enhancement while 12 had extensive (> 35%) enhancement. Overall 3 months post ablation LA scar was quantified in all patients. Only 10 patients (6.9%) had circumferential scar of all 4 PVs. Sixteen patients (11.1%) had 3 scarred veins, 19 patients (13.2%) had 2 scarred veins, 45 patients (31.3%) had 1 scarred vein, and 54 patients (37.5%) had no circumferentially scarred veins. PV scarring was the most important predictor of recurrence in the mild enhancement group (HR 0.37; p = 0.01), while overall scar was the most important predictor in the moderate enhancement group (HR 0.85; p = 0.02). In the extensive enhancement group, neither PV isolation nor overall scar were significant predictors of recurrence (HR 0.2; p = 0.10 and HR 1.09; p = 0.24).
Conclusion: Circumferential PV scaring is an important predictor of recurrence in patients with mild pre-ablation enhancement while overall is more important in moderate enhancement patients.