IL6 and periodontitis: The levels of serum inflammatory markers, such as C-reactive protein, and interleukin-6, were elevated in patients with periodontitis,26,40 and these markers were associated with AF risk.14,35 Thus, further longitudinal studies are needed to investigate the association between plasma antibody levels against PG and AF, in which AF is diagnosed based on an electrocardiogram, and systemic inflammation is assessed by serum inflammatory markers.