Optimal left atrial volume index cutoff for predicting atrial arrhythmia recurrence in atrial fibrillation patients undergoing pulmonary vein and posterior wall isolation

Atrial fibrillation (AF) recurrence remains a challenge, especially in patients with severely dilated left atria, who are often deemed unsuitable for catheter ablation due to perceived futility. Establishing an optimal left atrial volume index (LAVI) threshold could improve patient selection and enable more tailored ablation strategies, potentially enhancing outcomes.

To assess the efficacy and safety of PWI in addition to PVI for patients undergoing catheter ablation for AF with severe left atrial dilation, and to evaluate the optimal LAVI cutoff to predict arrhythmia recurrence.

A registry cohort study was conducted on consecutive atrial fibrillation patients who underwent catheter ablation from July 2020 to July 2023. Baseline and follow-up data were collected at 3-, 6-, and 12-months post-procedure. Ablation index (AI)-guided PVI was initially performed with power settings of 40-45 W, contact force of 5-20 g, and an inter-lesion distance of 4 mm. For PWI, recommended targets were a minimum contact force of 5 g, with an AI of 500-550 anteriorly and 350-400 posteriorly for the CARTO system or a Lesion Size Index of 5-6 anteriorly and 4 posteriorly for the Ensite system. Scar homogenization within the posterior wall was performed, with additional ablation targets selected at the operator's discretion. Esophageal retractor and temperature monitor were used in all patients. The acute procedural endpoint was confirmation of bidirectional block, verified through very high-output pacing at 25 mA/2 ms. Patients were monitored with 24-hour Holter recordings at 3-month intervals. The primary endpoint was freedom from documented atrial arrhythmia lasting more than 30 seconds, applying a 3-month blanking period. Statistical analysis was performed using R version 4.3.0.

At 12 months, there was no statistically significant difference in recurrence rates between patients with LAVI >48 ml/m² and those with LAVI <48 ml/m² (15% vs. 10%, p = 0.43). Patients with severe atrial dilation more commonly presented with persistent or long-standing persistent AF and reduced ejection fraction. The optimal LAVI cutoff to predict recurrence was found to be 40.5 ml/m2 (AUC 61.7%), indicating moderate discriminatory capability. Limitations include single-center design, retrospective analysis, and potential bias from non-random loss to follow-up.

In this cohort, LAVI showed a moderate correlation with AF recurrence, yet no significant difference in 12-month recurrence rates was found based on LAVI. Consequently, patient selection should not be restricted by left atrial volume alone. Extended follow-up or a larger sample may provide further insights.