ABSTRACT NUMBER: ESOC2026A1641 POST-COVID-19 ATRIAL FIBRILLATION: IMMUNE DYSREGULATION AND IMPLICATIONS FOR STROKE RISK

Abstract Background and aims COVID-19 has highlighted the link between systemic inflammation and cardiovascular complications, with atrial fibrillation (AF) being associated with poor prognosis and increased cardioembolic stroke risk. Methods The study included 165 patients (62.5 ± 0.9 years; 47% men, 53% women). 116 patients with AF post-COVID-19 were divided into three groups: G1 (n = 36) - new-onset AF after infection; G2 (n = 25) - progression from paroxysmal to persistent or persistent to permanent AF; G3 (n = 55) - AF without changes in form. The control group (CG) - 49 patients with AF without a history of COVID-19. Lymphocyte and monocyte subpopulations in peripheral blood were analyzed using flow cytometry. Results Comparison of NK cell parameters among the groups revealed no statistically significant differences. Patients with post-COVID AF progression (G2) had significantly lower T-helper cell levels compared to those with stable AF (G2 vs G3: 39.7 ± 1.57% vs 46.9 ± 6.0%, p < 0.05). CD3+CD8+ cytotoxic T lymphocyte levels were 67.3% higher in G2 compared to G3 (p < 0.05). B-lymphocyte levels were lower in G2 than in the control group (8.47 ± 0.60% vs 10.4 ± 0.20%, p < 0.005). The proportion of non-classical monocytes (CD14+dimCD16++) was higher in post-COVID AF patients compared to G3 (10.9 ± 0.63% vs 7.5 ± 0.40%, p < 0.001). Conclusions Post-COVID AF is associated with immune alterations, including reduced T-helper cells, increased cytotoxic T cells, lower B-lymphocytes, and elevated non-classical monocytes, which may contribute to AF progression and adverse outcomes. Conflict of interest Oksana Stasyshena:nothing to disclose