Pericarditis and myocarditis are local inflammatory conditions linked to the increased incidence of AF.81 Consistent with local inflammation contributing to arrhythmia, immune cells infiltrate the atria of AF patients,82 and activation of leukocytes is elevated in patients with perioperative AF.83 As an example, research found that CD45+ lymphocyte counts are higher in AF patients and CD68+ macrophage counts are higher in the atria of AF patients compared to in the control group.84 This suggests a link between inflammation and AF by immune cell infiltration into the atria. Here, CD68 is linked to pericarditis.