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Randomized Controlled Trial
. 2025 Jun;22(6):1384-1393.
doi: 10.1016/j.hrthm.2024.08.062. Epub 2024 Sep 6.

Lesion delivery and scar formation in catheter ablation for atrial fibrillation: The DECAAF II trial

Nazem Akoum  1 , Mario Mekhael  2 , Felipe Bisbal  3 , Oussama Wazni  4 , Christopher McGann  5 , Hyejung Lee  6 , Tyler Bardsley  6 , Tom Greene  6 , J Michael Dean  6 , Lilas Dagher  2 , Eugene Kholmovski  7 , Moussa Mansour  8 , Francis Marchlinski  9 , David Wilber  10 , Gerhard Hindricks  11 , Christian Mahnkopf  12 , Darryl Wells  5 , Pierre Jaïs  13 , Prashanthan Sanders  14 , Johannes Brachmann  12 , Jeroen J Bax  15 , Leonie Morrison-de Boer  6 , Thomas Deneke  16 , Hugh Calkins  5 , Christian Sohns  17 , Nassir Marrouche  18 ; DECAAF II investigators
Affiliations
Randomized Controlled Trial

Lesion delivery and scar formation in catheter ablation for atrial fibrillation: The DECAAF II trial

Nazem Akoum et al. Heart Rhythm. 2025 Jun.

Abstract

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.

Keywords: Atrial fibrillation; Atrial fibrosis; Cardiac magnetic resonance imaging; Catheter ablation; Lesion delivery.

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Conflict of interest statement

Disclosures Dr Marrouche reported other from Marrek (founder) and from ECG Check (previous shareholder) outside the submitted work and a patent issued for MRI fibrosis imaging. Dr Wazni reported personal fees (for consulting services) from Biosense Webster and Boston Scientific during the conduct of the study. Dr Greene reported personal fees from DURECT Corporation, Janssen Pharmaceuticals, and Pfizer and grants from Boehringer Ingelheim, AstraZeneca, and CSL outside the submitted work. Dr Dean reported grants from Boston Scientific, Medtronic, Siemens, Biosense Webster, and Abbott during the conduct of the study and grants from the National Institutes of Health outside the submitted work. Dr Kholmovski reported personal fees and other (share ownership) from Marrek during the conduct of the study and outside the submitted work, grants from Medtronic outside the submitted work, and a patent issued for US 9713436 licensed to Marrek, US 10004425 licensed to Marrek, and US 10726545 licensed to Marrek. Dr Mansour reported personal fees (for consulting services) from Biosense Webster, Boston Scientific, and Medtronic and personal fees (holding equity) from EPD Solutions and New Pace Ltd outside the submitted work. Dr Marchlinski reported personal fees (scientific advisory board) from Abbott Medical, Biosense Webster, and Medtronic outside the submitted work. Dr Wilber reported other (executive committee for the clinical trial) from Abbott and Boston Scientific; other (coprimary investigator, clinical trial) from AtriCure; grants from Abbott, AtriCure, and Biosense Webster; and personal fees from the American College of Cardiology Foundation (Editor-in-Chief of the Journal of the American College of Cardiology editor’s page), Biosense Webster (consulting), and Medtronic (lectures for fellows) outside the submitted work. Dr Jaïs reported grants from Biosense Webster and Boston Scientific during the conduct of the study and grants from Acutus and Medtronic outside the submitted work. Dr Sanders reported other (advisory board and research grants to his institution) from Medtronic, Abbott Medical, and Boston Scientific; other (advisory board) from CathRx and PaceMate outside the submitted work; and support by a practitioner fellowship from the National Health and Medical Research Council of Australia. Dr Brachmann reported grants from Medtronic and Biotronik during the conduct of the study and personal fees from Medtronic outside the submitted work. Dr Bax reported departmental unrestricted research grants from Abbott, Edwards Lifesciences, Medtronic, Biotronik, Boston Scientific, GE Healthcare, Novartis, and Bayer outside the submitted work. Dr Deneke reported grants (education) from Biotronik and personal fees (speaker) from Abbott and Boston Scientific (scientific committee) outside the submitted work. Dr Calkins reported personal fees from Biosense Webster, Abbott, and Boston Scientific outside the submitted work. No other disclosures were reported.

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