Association between patient characteristics and left atrial low voltage zones in atrial fibrillation patients undergoing pulmonary vein isolation

Abstract Background The importance of left atrial (LA) low voltage zones (LVZs) as a substrate for atrial fibrillation (AF) and predictor of clinical outcome is obscured due to inconsistent measurement criteria and cutoffs. Purpose This exploratory study aimed to systematically investigate the prevalence of LVZs in pre-ablation maps obtained with a state-of-the-art high-density mapping catheter and its association with baseline patient characteristics. Methods Our retrospective analysis included 114 patients (age 68±8 years, 38% female, 71% paroxysmal AF, LAVI 33 (27–41) ml/m2, LVEF 60 (56–64) %) referred for catheter ablation of atrial fibrillation at three tertiary care centres in Switzerland. Baseline demographic and clinical characteristics were collected from medical records and used for calculation of two established risk scores (APPLE score, DR-FLASH score). LVZs were assessed using high-resolution bipolar electroanatomic voltage mapping using a multipolar catheter. Presence of LVZ areas 1cm² and 5cm² for voltage cutoffs of ≤0.1mV, ≤0.2mV, 0.5mV and ≤1.0mV was evaluated for the LA globally as well as the roof, the posterior, and the anterior wall. Results LVZs were present in 60 of the 114 patients (52.6%). Patients with any LVZ (1cm2 and ≤0.5mV) were significantly older and showed higher LAVI and APPLE score compared to patients without LVZ. Univariate analysis identified 10 out of 15 baseline variables as significant predictors of LVZ presence, with notable differentiation between global and regional associations. For all voltage cutoff 0.5mV, the significant predictors were age (OR: 1.041 95% CI 1.022-1.063, p0.001), APPLE score (OR: 1.722 95% CI 1.041-2.069, p0.001), and LAVI (OR: 1.043 95% CI 1.027-1.060, p0.001). In a sub analysis, APPLE score and age were more predictive globally and anteriorly, whereas LAVI was more predictive for posterior LVZ. Of note, a significant difference in LVZ presence between the paroxysmal and persistent groups was detected only at the anterior wall with a 0.2mV cut-off, where 2.7% of persistent AF patients exhibited a LVZ compared to 0.6% of paroxysmal AF patients (p=0.024). Conclusion Baseline characteristics are strong and region-specific predictors of LVZ presence, highlighting their value in identifying LA substrate. In this cohort of patients with AF undergoing a first PVI, age, indexed left atrial volume and the APPLE AF recurrence risk score were independently associated with low voltage zones in the left atrium, whereas AF type is not. Future studies should determine whether these associations can support a more personalized, substrate-driven treatment strategy.