Prognostic value of left atrial stiffness index in patients undergoing catheter ablation for atrial fibrillation

Background Left atrial volume index (LAVI) is the standard marker for risk stratification in patient with atrial fibrillation (AF) undergoing catheter ablation. However, volumetric assessment alone does not fully capture the heterogeneity of atrial remodeling. Although integrating low-voltage area (LVA) with LAVI improves risk prediction, LVA is an invasive intra-procedural parameter. Because LVA reflects atrial fibrosis and increased chamber stiffness, the left atrial stiffness index (LASI), measured by echocardiography, may serve as a non-invasive marker for pre-procedural risk assessment. Purpose We aimed to investigate whether LASI refines risk stratification by identifying low-risk patients with enlarged LAVI and high-risk patients among those with normal LAVI. Methods In this multicenter observational study, we analyzed consecutive patients who underwent initial catheter ablation for AF between Aug 2021 and Nov 2025. Patients with prior pulmonary vein isolation or missing echocardiographic data were excluded. LASI was calculated as E/e' divided by peak left atrial reservoir strain obtained from pre-procedural echocardiography. Patients were stratified into four groups based on the median values of LAVI and LASI to compare their respective clinical outcomes. The primary endpoint was AF recurrence within 1 year following the procedure, evaluated after a 3-month blanking period. Results Among 467 screened patients, 384 patients were included in the final analysis (mean age: 67 years; 34% female; 65% patients paroxysmal AF; median LAVI: 41.0 [IQR: 32.1–53.2] mL/m²; median LASI: 0.54 [IQR: 0.33–0.94]). During a median follow-up of 312 days, AF recurrence occurred in 74 (19%) patients. Patients with both high LAVI and high LASI had the highest recurrence rate (log-rank P = 0.002, Figure1A). LASI was not associated with recurrence in patients with low LAVI Group (Figure1B). However, within the high LAVI, high LASI was significantly associated with recurrence compared with low LASI (hazard ratio: 3.44; 95% confidence interval: 1.45–8.15; P = 0.003, Figure1C). Notably, after stratification by LASI, LAVI was not significantly associated with AF recurrence in either subgroup. In multivariable Cox analysis, the four-group classification combining LAVI and LASI remained an independent predictor of AF recurrence. Conclusion Integrating LASI with conventional volumetric assessment enables more precise risk stratification before AF ablation. In patients with AF, a higher LASI may reflect more advanced structural atrial remodeling and help stratify atrial remodeling beyond chamber enlargement. Risk stratification based solely on LAVI may be insufficient to fully capture the heterogeneous nature of atrial remodeling, as patients with enlarged LAVI demonstrated favorable outcomes when LASI was low.