Mri-guided approach to localize and ablate gaps in repeated atrial fibrillation ablation procedure

Abstract

Introduction: Recurrences of atrial fibrillation (AF) after pulmonary vein (PV) isolation may be related to gaps at the ablation lines. Delayed-enhanced cardiac magnetic resonance (DE-CMR) allows the identification of radiofrequency (RF) lesions and gaps (CMR gaps). The present study aimed to test the usefulness of a new DE-CMR guided approach to ablate gaps in re-do procedures. Methods: Using DE-CMR, a 3D volume-rendered left atrial reconstruction (3D model) was created, after manually segmenting endocardium and epicardium. A pixel signal intensity map was projected on the 3D model and color-coded. The 3D model was imported into the navigation system. RF was delivered targeting the CMR gaps, with the operator blinded to electrical data. Results: Twelve patients were analyzed (58±8 years, 7 with paroxysmal AF, median [IQR] time from prior PV isolation of 16.5 [9-25.5] months). Four patients had additional roof-line ablation. In total, 68 CMR gaps were identified around the PVs and 13 at the roof-line, with a mean of 6.8 gaps/patient and median length of 5.5 mm/gap. Of 43 PVs 38 were electrically reconnected (median of 3 PV/patient). All reconnected PVs presented CMR gaps, with functional electrical-CMR concordance of 88.9%. Guided by the 3D model, isolation of 95% of PVs and conduction block through the roof-line was achieved after a mean of 3.7±3.4 RF applications/gap (22.0±20.2/patient) and 2.8±2.2 min/gap (29.3±14.0 min/patient). Conclusion: DE-CMR is a useful tool to guide the repeat PV isolation procedure by accurately identifying and locating the gaps, with the potential of reducing procedure duration and RF application time.