ABC | Volume 114, Nº4, April 2020

Original Article Extent of Left Atrial Ablation Lesions and Atrial Fibrillation Recurrence after Catheter Ablation – A Systematic Review and Meta-Analysis Eduardo Thadeu de Oliveira Correia, 1 Letícia Mara dos Santos Barbetta, 1 Evandro Tinoco Mesquita 1 Hospital Universitário Antonio Pedro, 1 Niterói, RJ – Brazil Mailing Address: Eduardo Thadeu de Oliveira Correia • Hospital Universitário Antonio Pedro - Avenida Marquês do Paraná, 303. Postal Code 24033-900, Centro, Niterói, RJ – Brazil E-mail: etocorreia@outlook.com Mansucript received November 26, 2018, revised manuscript April 29, 2019, accepted June 05, 2019 DOI: https://doi.org/10.36660/abc.20180378 Abstract Background: Atrial fibrillation (AF) is known to induce atrial remodeling, which promotes fibrosis related to arrhythmogenesis. Accordingly, since scars induced by catheter ablation (CA) can reduce unablated fibrotic areas, greater extent of left atrial (LA) scarring may be associated with less AF recurrence after CA. Objectives: This study aims to investigate, through systematic review and meta-analysis, whether the amount of LA scarring, seen on late gadolinium enhancement magnetic resonance imaging, is associated with less AF recurrence after CA. Methods: The recommendations of the MOOSE guideline were followed. Database search was conducted in PubMed and Cochrane Central Register of Controlled Trials (comentário 1) until January 2019 (comentário 2). Two authors performed screening, data extraction, and quality evaluation. All studies were graded as good quality. A funnel plot was generated, showing no publication bias. Statistical significance was defined as p value < 0.05. Results: Eight observational studies were included in the systematic review, four of which were included in the meta‑analysis. Six of the eight studies included in the systematic review showed that greater extension of LA scarring is associated with less AF recurrence after CA. Meta‑analysis showed that greater extension of LA scarring is associated with less AF recurrence (SMD = 0.52; 95% CI 0.27 – 0.76; p < 0.0001). Conclusion: Greater extension of LA scarring is possibly associated with less AF recurrence after CA. Randomized studies that explore ablation methods based on this association are fundamental. (Arq Bras Cardiol. 2020; 114(4):627-635) Keywords: Atrial Fibrillation; Catheter Ablation; Heart Atria/injuries; Meta-Analysis as Topic; Databases,Bibliographic. Introduction Radiofrequency catheter ablation (RFCA) is a standard procedure for correction of atrial fibrillation (AF) in patients who have not responded to previous antiarrhythmic drug therapies. 1 However, this procedure is related to high AF recurrence rates, even in the best hands. 2 Accordingly, electrophysiologists and interventional cardiologists are seeking techniques that aim to reduce AF recurrence. AF is known to induce atrial remodelling, increasing the amount of fibrotic tissue in themyocardium, which can promote atrial arrhythmogenesis, reinforcing the vicious cycle of AF. 3-5 In this manner, since the scars induced by catheter ablation (CA) can reduce unablated fibrotic areas, the extent of the left atrial (LA) scars could be associated with less AF recurrence after CA. However, there are currently no systematic reviews or meta‑analyses that have investigated this relationship, although they are the highest quality of evidence available. Accordingly, this systematic review and meta-analysis aims to investigate if the amount of LA scarring, visualized by late gadolinium-enhanced magnetic resonance imaging (LGE-MRI), could be associated with less AF recurrence after CA, which can provide a solid background for designing new ablation strategies that improve patient outcomes. Methods A systematic review was performed according to the criteria established by the Meta-analysis of Observational Studies in Epidemiology (MOOSE) Group. 6 Search strategies Two investigators (ETOC and ETM) searched the PubMed and Cochrane Central Register of Controlled Trials, until January 2019. The search strategy comprised a combination of English terms and Medical Subject Headings (MeSH) descriptors, consisting of nine keywords [(left atrial OR left atrium) AND (scar OR scarring OR remodelling OR fibrosis OR enhancement) AND (ablation OR pulmonary vein isolation)]. A manual search of references was also used to identify possible studies for inclusion. Each title and abstract were independently analyzed by both investigators, who selected the articles which were relevant to the review. Subsequently, the full texts of the remaining articles were reviewed to select which 627