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Introduction: The presence of low-voltage zones (LVZs) in the left atrium (LA) is associated with the recurrence of atrial fibrillation (AF) following pulmonary vein isolation (PVI). However, there is variability and conflict in the data regarding predictors of LVZs as reported in previous studies. The objective of this study was to identify predictors for the presence of LVZs in a cohort of patients with persistent AF., Methods: The study prospectively enrolled 439 patients with persistent AF who were scheduled for ablation. Voltage map of the LA was collected using a multipolar catheter. An LVZ was defined as an area of ≥3 cm 2 exhibiting a peak-to-peak bipolar voltage of <0.5 mV., Results: The mean age of the cohort was 65.3 ± 8.6 years and 26.4% were female. Additionally, 25.7% had significant LVZs, most frequently located in the anterior wall of the LA. Multivariable analysis identified the following independent predictors for LVZ: advanced age (OR [odds ratio] = 1.08, 95% CI [confidence interval] = 1.03-1.13, p = .002); female sex (OR = 4.83, 95% CI = 2.66-8.76, p < .001); coronary artery disease (CAD) (OR = 3.20, 95% CI = 1.32-7.77, p = .01) and enlarged LA diameter (OR = 1.10, 95% CI = 1.04-1.17, p = .001). The area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the final model was 0.829., Conclusion: Approximately 25% of the patients with persistent AF had LVZs. Advanced age, female sex, CAD, and a larger LA were independent predictors for LVZs with the model demonstrating a very good AUC for the ROC curve. These findings hold the potential to be used to tailor the ablation procedure for the individual patient., (© 2024 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Inflammation has been suggested to play a key role in the pathogenesis of atrial fibrillation (AF). Our hypothesis was that this inflammation, mediated by intermediate monocytes and toll-like receptor 4 (TLR4), causes the formation and expansion of low-voltage zones (LVZs). Prior to ablation, the monocyte subsets of 78 AF patients and TLR4 expression of 66 AF patients were analyzed via a flow cytometric analysis. Based on the CD14/CD16 expression, the monocytes were divided into three subsets: classical, intermediate, and non-classical. At the beginning of the ablation session, voltage mapping was performed. LVZs were defined as all bipolar electrogram amplitudes of < 0.5 mV. Correlations between the flow cytometric analysis results and presence of LVZs, as well as the total area of the LVZ, were examined. Patients with LVZs clearly had a higher proportion of intermediate monocytes (10.0 ± 3.6% vs. 7.2 ± 2.7%, p < 0.001) than those without LVZs. TLR4 was much more frequently expressed in the intermediate monocytes than other two monocyte subsets (p < 0.001). Moreover, the TLR4 expression level in intermediate monocytes correlated positively with the total area of the LVZs (r = 0.267, p = 0.030), especially in patients with paroxysmal AF (r = 0.365, p = 0.015). The intermediate monocytes and TLR4 expression positively correlated with LVZs in AF patients.