Left atrial fibrosis progression detected by LGE‐MRI after ablation of atrial fibrillation.

Background: Left atrial (LA) fibrosis is thought to be a substrate for atrial fibrillation (AF) and can be quantified by late gadolinium enhancement magnetic resonance imaging (LGE‐MRI). Fibrosis formation in LA is a dynamic process and may either progress or regress following AF ablation. We examined the impact of postablation progression in LA fibrosis on AF recurrence. Methods: LA enhancement in LGE‐MRI was quantified in 127 consecutive patients who underwent first time AF ablation. Serial LGE‐MRIs were done prior to AF ablation, 3 months postablation and at least 12 months after second LGE‐MRI. Transient postablation lesion (TL) was defined as atrial enhancement caused by ablation lesions that was detected on the first (3 month) but not on the second postablation LGE‐MRI. New fibrosis (NF) was defined as atrial enhancement detected on the most recent LGE‐MRI, at least 15 months after the ablation procedure. AF recurrence and its correlation with TL and NF was assessed in all patients during the follow‐up period. Results: An increase of 1% NF increased the chance of postablation AF recurrence by 3% (hazard ratio [HR] 1.03, 95% CI 1‐1.06, P =.05). TL had no significant impact on recurrence (P =.057). After adjusting for cardiovascular risk factors, HR increased as NF became greater. Greater volume of NF (≥21%) corresponded with lower arrhythmia‐free survival (37% vs 62%, P =.01). Conclusion: NF formation postablation of AF is a novel marker of long‐term procedural outcome. Extensive NF is associated with significantly higher risk of atrial arrhythmia recurrence. [ABSTRACT FROM AUTHOR]