Heart rhythm, 6 1 2024, Pages S1547-5271(24)03288-0 Lesion delivery and scar formation in catheter ablation for atrial fibrillation: The DECAAF II trial. Akoum N, Mekhael M, Bisbal F, Wazni O, McGann C, Lee H, Bardsley T, Greene T, Dean JM, Dagher L, Kholmovski E, Mansour M, Marchlinski F, Wilber D, Hindricks G, Mahnkopf C, Wells D, Jaïs P, Sanders P, Brachmann J, Bax JJ, Morrison-de Boer L, Deneke T, Calkins H, Sohns C, Marrouche N, DECAAF II investigators
Background
The Efficacy of Delayed Enhancement MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation of Atrial Fibrillation randomized trial showed no difference in atrial fibrillation (AF) recurrence with additional delayed enhancement magnetic resonance imaging (DE-MRI) fibrosis-targeted ablation to pulmonary vein isolation (PVI) in persistent AF.
Objective
We evaluated the effect of lesion delivery on ablation-induced scarring and AF recurrence.
Methods
Lesions delivered, targeting fibrotic and nonfibrotic areas identified from preablation DE-MRI, were studied in relation to ablation-induced scarring on 3-month DE-MRI, including their association with arrhythmia recurrence.
Results
A total of 593 patients treated with radiofrequency were analyzed: 293 (49.4%) underwent PVI and 300 (50.6%) underwent additional fibrosis-guided ablation. Lesion analysis showed that 80.9% in the MRI fibrosis-guided group vs 16.5% in the PVI group (P < .001) had ≥40% of baseline fibrosis targeted. MRI assessment of ablation-induced scar showed that 44.8% of fibrosis-guided ablation and 15.5% of PVI had ≥40% of their fibrosis covered by scar (P < .001), demonstrating significant attenuation from lesions delivered to scar formed. In the overall population, fibrosis coverage with scar was not associated with recurrence (hazard ratio [HR] 0.90; 95% confidence interval [CI] 0.80-1.01; P = .08 per 20% increase). In patients with baseline fibrosis < 20%, fibrosis coverage with scar was associated with lower recurrence than PVI (HR 0.85; 95% CI 0.73-0.97; P = .03), whereas the association was not significant when baseline fibrosis ≥ 20% (HR 0.97; 95% CI 0.80-1.17; P = .77). Significant center variation was observed in fibrosis targeting and coverage with scarring.
Conclusion
Radiofrequency ablation lesions do not uniformly result in scar formation. A post hoc analysis suggests reduced arrhythmia recurrence when ablation-induced scarring covers fibrotic regions in patients with low baseline fibrosis.
