Discordance between left atrial volume and scar burden in patients with atrial fibrillation and its impact on atrial fibrillation recurrence after catheter ablation

Large left atrial (LA) volume and a high burden of LA low voltage zone (LVZ) are associated with atrial fibrillation (AF) recurrence after AF catheter ablation. There is a scarcity of information on the association between LA volume and LVZ and its impact on the risk of AF recurrence.

To investigate the relationship between the LA volume and LVZ, as well as how these factors contribute to the recurrence of atrial fibrillation (AF).

From Nov 2021 to Oct 2023, drug-refractory AF patients who underwent AF catheter ablation were included. LA volume was assessed using the LA volume index (LAVI) using echocardiography. The LVZ was evaluated by conducting high-density electroanatomical mapping using a multipolar catheter. The cut-off value associated with AF recurrence was 48ml/m2 in LAVI and 4.5% in scar burden. Patients were categorised into four groups according to the LAVI and scar burden: Group 1 (Low LVZ and small LA), group 2 (Low LVZ and large LA), group 3 (High LVZ and small LA), and group 4 (High LVZ and large LA).

A total of 170 patients were included (mean age 62± 9 years, 82% of men, 68.2% of non-paroxysmal AF and 81 [48%] in group 1; 32 [19%] in group 2, 27 [16%] in group 3, 30 [17%] in group 4, respectively). Among total, mean follow-up duration was 266.5 ± 174.4 days, and 8.8% of patients received additional LA ablation beyond pulmonary vein isolation. Among the four groups, group 2 and 4 were significantly associated with higher risks of AF recurrence compared to group 1 (HR 2.36 [1.04-5.34], p=0.039; 3.56 [1.59-7.95], p=0.002, respectively). The risk of AF recurrence was highest in group 4, followed by group 2 (log-rank P=0.002). Comparing group 2 and 3, AF recurrence occurred predominantly within 6-month after catheter ablation in group 2, while after 1-year in group 3 (log-rank P=0.83).

About one-third of patients showed discordance between the LAVI and LVZ, which are both independent predictors for AF recurrence. A substantial LA volume seems to contribute to early AF recurrence, whereas a high scar burden appears to affect late AF recurrence.