Left Atrial Fibrosis Amelioration Following Cardioversion Assessed with LGE-MRI in Patients with Persistent Atrial Fibrillation

Background: Previous studies have demonstrated that cardioversion of atrial fibrillation may alleviate atrial remodeling. We aimed to investigate whether left atrial (LA) tissue fibrosis assessed by LGE-MRI, may be reversed after conversion of persistent atrial fibrillation (PersAF) to sinus rhythm. Methods: Patients with PersAF underwent two LGE-MRI scans following cardioversion were prospectively recruited. LA fibrosis was categorized into core zone (IIR > 1.61) and border zone (0.97<IIR-1.61) based on the image intensity ratio (IIR). Reverse remodeling of LA was defined as at least a 15% reduction in the max LA volume (LAV). The differences in baseline and follow-up LA structure, function and quantified fibrosis were compared. Multivariable analysis was used to assess the associations of border and core zone changes with other LA parameters. Results: Fifty-three patients were included. The area of the border [22.2 (11.8- 37.0) vs. 18.1 (11.8- 25.2) cm2, p= 0.037] and core zones [0.9±3.0 vs. 0.1±0.6 cm2, p= 0.010] decreased from baseline, along with reductions in LAV, increase of LA ejection fraction and strain. After multivariable adjustment, LATEF was correlated with border zone (r2=0.155, p= 0.015), baseline left ventricular mass and LATEF was correlated with core zone (r2=0.286, p<0.001). The cardiac reverse remodeling is not related with border zone and core zone. Conclusions: Atrial fibrosis improved concomitantly with LA shrinkage and enhanced LA function after PersAF to sinus rhythm. LA fibrotic reverse is an independent parameter compared with the traditional definition of cardiac reverse remodeling. The clinical implications warrant further investigation.