Atrial functional mitral regurgitation as a marker of atrial remodeling and ablation outcomes in atrial fibrillation patients

Abstract Background Atrial fibrillation (AF) triggers a cascade of atrial remodeling processes, significantly impacting atrial function and the efficacy of ablation therapies. This remodeling fosters the development of atrial cardiomyopathy and atrial dilation, which is linked to the emergence of mitral regurgitation, paving the way for the concept of atrial functional mitral regurgitation (aFMR). Our study delves into the intricate relationship between aFMR and the electrical architecture of the atrium, specifically focusing on left atrial bipolar voltage and the prevalence and extent of low-voltage areas (LVAs) in AF patients. By exploring these associations, this research aims to deepen our understanding of the interplay between the atrial substrate alterations and the development of aFMR. Methods A total of 282 patients were enrolled, who had presented for a redo PVI procedure after experiencing AF recurrence following a previous PVI. All patients received echocardiography prior to the electrophysiological procedure. All procedures were performed using 3D mapping and radiofrequency ablation. Reconnected pulmonary veins were detected in all patients and were re-isolated. The voltage of the electroanatomical points was documented on each of the atrial walls. LVAs were calculated in selected HD maps. Patients were followed-up for one year after the blanking period. Results Our cohort comprised 282 patients, predominantly male (69.4%), with a mean age of 64 years. 56% of the patients presented with persistent AF. LA area was larger in patients with aFMR ≥ 1+ as compared to aFMR 1+ (17.0 14.6-19.7 vs 20.6 16.6-24.7 cm2, p0.001). We observed significant differences in left atrial voltage and LVA extent between patients with varying degrees of aFMR (Table 1). Upon further investigation Patients with aFMR = 1+ showed significantly lower atrial voltage compared with aFMR 1+ yet no significant increase in LVAs area. Patients with aFMR = 2 exhibited lower average voltage amplitudes in all atrial regions and larger LVA in the posterior wall, atrial roof, and septum compared to their aFMR 1+ counterparts. Notably, the recurrence of AF was significantly higher in the AFMR ≥ 1+ (59% vs 46% p=0.027) group within one year of follow-up. aFMR was associated with AF recurrence even after adjusting for sex, age and AF types (HR:1.517, 95% CI: 1.057-2.184, p=0.025). Conclusion The presence of aFMR in AF patients may serve as a marker of progressive atrial remodeling and the onset of left atrial cardiomyopathy, characterized by reduced atrial voltage and increased LVAs. Additionally, aFMR is linked to the outcomes of PVI, suggesting that aFMR should be considered in the decision-making process for AF therapy. Further research is needed to explore the potential reversibility of these changes.Left atrial voltage and low voltage area