Cardiac magnetic resonance imaging for post-ablation lesion assessment and guiding re-ablation strategies in patients with paroxysmal atrial fibrillation

Atrial fibrillation (AF) recurrence after catheter ablation (CA), often due to incomplete lesions, remains a challenge. In this study, we evaluate the role of cardiac magnetic resonance (CMR) in characterizing lesion formation and guiding re-ablation strategies in patients with paroxysmal AF undergoing radiofrequency catheter ablation (RFCA). This prospective, single-center study enrolled patients undergoing first-time RFCA for paroxysmal AF. Pre-ablation CMR was performed for functional, anatomical, and fibrosis assessment. Repeat CMR 3 months post-ablation was performed to quantify fibrosis using Image Intensity Ratio (IIR) and detect lesion gaps, defined as ≥ 3 mm discontinuities in late gadolinium enhancement (LGE). AF recurrence was monitored for 18 months. 25 patients (20% female) were enrolled. 8/25 patients (32%) experienced AF recurrence. Post-ablation CMR showed significantly increased atrial fibrosis, though only in 2/25 patients (8%) complete circumferential pulmonary vein (PV) lesions were observed. Fibrosis burden did not differ significantly between patients with and without recurrence. Among 6 patients undergoing repeat ablation, 3 with LGE-defined gaps in circumferential lesions were successfully treated with a single re-isolation procedure. In contrast, 3 patients with extensive lesions and minimal or no gaps required multiple repeat procedures and additional ablation at extra-pulmonary vein sites. CMR can be a useful tool to assess post-ablation lesions and detect gaps after RFCA for paroxysmal AF. This may help distinguish recurrence due to insufficient initial ablation from other arrhythmogenic triggers, thereby guiding tailored and effective re-ablation strategies.