The Electroanatomic Volume of the Left Atrium as a Determinant of Recurrences in Patients with Atrial Fibrillation After Pulmonary Vein Isolation: A Prospective Study

Abstract

Background/Objectives: Catheter ablation for atrial fibrillation (AF) is a well-established therapeutic approach for maintaining sinus rhythm, though its efficacy remains suboptimal in certain patients. The left atrium (LA) volume, commonly assessed through transthoracic echocardiography (TTE), is a recognized predictor of AF recurrence after pulmonary vein isolation (PVI). However, the complex three-dimensional structure of the LA makes precise measurement challenging with traditional TTE techniques. Electroanatomic mapping (EAM) offers a more accurate evaluation of LA geometry and volume, which may enhance the prediction of ablation outcomes. Methods: This prospective study included 197 patients with AF who were referred for PVI to our center (Hospital Universitario Central de Asturias, Spain) between 2016 and 2020. All participants underwent pre-ablation TTE and EAM to assess the electric active volume (EAV) of the LA. Clinical follow-up included regular Holter monitoring and electrocardiograms to detect AF recurrences. Results: The mean age was 56.3 ± 9.67 years, and 34% had persistent AF. The mean LA volumes measured by TTE and the EAV by EAM were 62.86 ± 15.58 mL and 126.75 ± 43.35 mL, respectively, with a moderate positive correlation (r = 0.49, p < 0.001). AF recurrences were observed in 51.27% of patients over a 36 ± 15-month follow-up period. Cox regression analyses (univariate and multivariate), Kaplan-Meier curves and log-rank tests were used to illustrate freedom from atrial arrhythmia during follow-up. Both EAV by EAM and TTE volumes were significant predictors of AF recurrence in the univariate analysis (HR 1.002 [1.001-1.003], p = 0.033 and HR 1.001 [1.006-1.012], p < 0.01, respectively). Among clinical variables, persistent AF was significantly associated with a higher risk of recurrence (HR 1.17 [1.096-1.268], p = 0.02). Conclusions: EAV of the LA assessment by EAM demonstrates a significant correlation with TTE measurements and is a predictor of AF post-ablation recurrence. In patients selected for catheter ablation, EAV by EAM provides additional insights that could contribute to therapeutic decision-making and risk stratification of AF recurrences.

Keywords: atrial fibrillation; catheter ablation; echocardiography; electroanatomic mapping.

Figure 1

Study design flowchart. EAV, electrically active volume; ECG, electrocardiogram; PV, Pulmonary veins; PVI, Pulmonary vein isolation.

Figure 2

Sample case of left atrial electrically active volume (EAV) quantification using electroanatomic mapping. (A) Anterior view. (B) Posterior view. Upper panels display EAV quantified between the plane of the mitral valve and the external limit of the pulmonary veins (PV) set by voltage mapping at 0.2 mV. Lower panels display quantification of excluded atrial volumes by the circumferential pulmonary vein isolation (CPVI) lines.

Figure 3

Comparison between Left Atrial volume measured with transthoracic echocardiography and the electrically active volume by EAM. The regression line is plotted in red. EAM: electroanatomic mapping.

Figure 4

Cumulative risk of Atrial Fibrillation recurrence during follow-up depending on Left Atrial (LA) volume. (A) LA volume measured by transthoracic echocardiography; red indicates LA volume <60 mL and blue indicates LA volume >60 mL. (B) Electrically active volume (EAV) measured by electroanatomic mapping; red indicates EAV <145 mL, and blue indicates EAV >145 mL.

Figure 5

Comparative ROC curves of measurements by transthoracic echocardiography (TTE) and electrically active volume measured by electroanatomic mapping (EAV by EAM), demonstrating similar predictive capabilities for both diagnostic tests.