Clinical utility of cardiac magnetic resonance imaging to assess the left atrium before catheter ablation for atrial fibrillation - A systematic review and meta-analysis.

Aims: This systematic review and meta-analysis aims to clarify the role of pre-procedural cardiac magnetic resonance imaging (MRI) in identifying the association between left atrial (LA) characteristics and post-ablation atrial fibrillation (AF) recurrence. These characteristics include LA fibrosis, emptying function, sphericity, volume, volume index, peak strain and post-contrast T1 relaxation time.
Methods: PubMed, EMBASE, and Cochrane were searched up to July 2020 for English language articles reporting the use of cardiac MRI in catheter ablation for AF. Studies reporting the prognostic value of pre-ablation cardiac MRI were included. All references and citations were filtered for relevant manuscripts.
Results: Twenty-four publications were identified. Every 10% increase in LA fibrosis was associated with a 1.54-fold increase in post-ablation AF recurrence (95%CI: 1.39-1.70, I ²  = 50.1%). Every 10 ml increase in LA volume resulted in a hazard ratio of 1.07 (95%CI:1.03-1.12; I ²  = 41.4%) for post-ablation AF recurrence. For LA sphericity, there was no significant association with post-ablation AF recurrence (HR: 1.032 [95%CI: 0.962-1.103, I ²  = 49.6%). Egger's test was non-significant for publication bias in all meta-analyses. LA volume index, emptying function, peak strain and post-contrast LA T1 relaxation time had insufficient compatible publications to conduct a meta-analysis.
Conclusion: LA fibrosis quantified by cardiac MRI is associated with risk of AF recurrence after AF ablation, while increased LA volume is associated with AF recurrence to a lesser extent. There remains insufficient evidence to support the routine measurement of LA sphericity, LA volume index, LA emptying function, peak strain and LA T1 relaxation time to predict AF recurrence after AF ablation.
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