Left atrial functional and structural changes associated with ablation of atrial fibrillation - Cardiac magnetic resonance study

Abstract

Introduction: Left atrial (LA) volumes are related to success of atrial fibrillation (AF) ablation, but the relation to other functional and structural parameters is less well understood. Our goal was to detect potential functional and structural predictors of arrhythmia recurrence after ablation using cardiac magnetic resonance imaging (CMRi) and to non-invasively assess the relation between LA functional and structural remodeling pre- and post-ablation.

Methods: A total of 55 patients (38 male, age 67 ± 10 years) underwent CMRi prior to and then within 24-h and 3-months after ablation. LA volumes (LAV) and function (as assessed by ejection fraction and peak longitudinal atrial strain (PLAS)) were measured by feature-tracking CMRi, and LA fibrosis/scarring was quantified using late‑gadolinium enhancement (LGE) imaging.

Results: Atrial function was lower acutely in patients with recurrence versus those with non-recurrence: [R vs NR: EF_Total 27.8 ± 10.3% vs 38.1 ± 11% p = 0.002; EF_Active 10.5 ± 8% vs 19.1 ± 12% p = 0.007; EF_Passive 19.4 ± 8 vs 25.8 ± 10 p = 0.021; PLAS 13 ± 5.9% vs 20.2 ± 7% p = 0.004]. With univariate analysis, baseline minimum volume (MinLAV, MinLAVi), several baseline functional parameters (EF_Total, EF_Passive, EF_Active, PLAS), and LA-LGE were predictors of recurrence [all p < 0.05]. Acute function (EF_Total, EF_Passive, EF_Active, PLAS) also predicted recurrence (p < 0.01). Lower pre-ablation EF_Total, EF_Passive, and PLAS correlated with higher amount of pre-ablation LA-LGE (p < 0.05). In a multivariate model including MinLAV, EF_Active and LA-LGE (all at baseline), LA-LGE was the only independent predictor of recurrence (p = 0.0322).

Conclusion: Pre-ablation function inversely correlated with LA-LGE and was related to success of AF ablation. Multi-parametric and longitudinal assessment of LA function and structure could be helpful in selection of optimal treatment strategies for AF patients by predicting outcomes.

Keywords: Ablation; Atrial fibrillation; Cardiac magnetic resonance; Recurrence.