Left atrium regional voltage analysis in sinus rhythm in patients undergoing atrial fibrillation ablation

Abstract

Background: The analysis of the amplitude of the electrograms (EGM) obtained during electroanatomic mapping of the atria during atrial fibrillation (AF) ablation could identify low voltage areas (LVA) as a marker of atrial remodelling and predict a worse outcome in the follow-up. Aims: To evaluate the presence of LVA in sinus rhythm (SR) in the patients with paroxysmal and persistent AF undergoing ablation and to correlate it with the specific clinical features and the recurrence rate in the follow-up of this population. Method: We evaluated the voltages of the EGM obtained during electroanatomic mapping of 43 patients undergoing AF ablation (age: 54±11 years; 79% men; 35% persistent AF; mean AF duration: 52±41 months; LA diameter: 44 mms (33-54), by analysing 29 segments of the left atrium (LA) corresponding to 5 anatomical regions (posterior and anterior walls, septum, roof and bottom) and 12 segments of the right atrium (RA) in sinus rhythm before AF ablation. The patients in AF at the beginning of the procedure were cardioverted before EGM acquisition. Only the points showing an adequate catheter-tissue contact were taken into account. The points with EGM voltage amplitude ≤ 0.5 mV were defined as LVA. Pulmonary veins isolation was the endpoint of the procedure in all cases. Additional ablation lines were performed in the roof and mitral isthmus in patients with persistent AF. Results: We did not find any LVA in patients with paroxysmal AF. LVA were present in 7 (47%) of the patients with persistent AF, located in the posterior (7 cases) and anterior walls (1 case), septum (2 cases) and roof (3 cases) of the LA. We did not find any LVA in the RA in any patient. The presence of LVA was not related to the coexistence of hypertension, older age, lower LA appendix velocity or AF duration. On the other hand, patients with LVA showed a larger echocardiographic LA diameter that patients without LVA (52 mms versus 43 mms; p=0.03). At a mean follow-up of 16±10 months, the patients with persistent AF and LVA showed a significant higher AF recurrence rate that patients with persistent AF without LVA (86% versus 25%; p=0.02). Conclusions: The presence of LVA in patients with persistent AF undergoing ablation procedures is frequent. LVA are mainly located in the posterior wall of the LA and their presence is related to a higher recurrence rate in this population in the follow-up. The echocardiographic LA diameter can be an accurate clinical predictor of the presence of LVA.