Several inflammatory cytokines and T-cell surface antigens, including C-reactive protein (CRP), uric acid/albumin ratio, interleukin (IL)-6, IL-1β, myeloperoxidase (MPO), tumor necrosis factor-α (TNF-α), cluster of differentiation (CD)3, CD4, and CD8, have been identified as biomarkers for predicting the incidence of AF and/or the outcome of AF ablation [9–14]. The gene discussed is CD8A; the disease is atrial fibrillation.