Monocyte Toll-Like Receptor Expression in Patients with Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia. Inflammation has been suggested to play a vital role in the pathogenesis. Previous studies have investigated expression of inflammatory markers in AF. Several studies have focused on the effects of toll-like receptors (TLRs) on heart in terms of capability of modulating inflammation. In this study, we aimed to investigate whether peripheral monocyte TLR expression was associated with the AF presence, and recurrence of AF after cryoablation, as a reflection of inflammatory status. Patients with AF who were scheduled for cryoballoon-based ablation for AF and age- and gender-matched subjects in sinus rhythm were included. Peripheral monocyte TLR-2 and TLR-4 expressions were evaluated by flow cytometric analysis in peripheral venous blood samples obtained during evaluation in outpatient clinics: 172 patients (56.5 ± 6.6 years, 52.3% men) were included in the study. Peripheral monocyte TLR-2 and TLR-4 expression levels were significantly higher in patients with AF (p <0.05). Among patients with AF, 12 patients (14.0%) developed AF recurrence at a follow- up of 17 months. Multivariate Cox regression analysis showed that left atrial volume index (hazard ratio 2.040, 95% CI 1.197 to 3.477, p = 0.009) and monocyte TLR-4 expression (hazard ratio 1.226, 95% CI 1.042 to 1.443, p = 0.014) were independent predictors of AF recurrence after blanking period following second-generation cryoballoon-based pulmonary vein isolation for paroxysmal AF. In conclusion, our study highlights the role of TLR-mediated inflammation in the pathogenesis of AF. This link may also constitute a therapeutic target in patients with AF.