IL6 and atrial fibrillation: The percentage of IL-6 positive NP cells was significantly lower in the REC+UPAL group than in the UPAL group on postoperative day 7 (p < 0.01), and for IL-6 positive AF cells, the percentage was significantly lower on days 1 and 7 (p < 0.01, p < 0.01, respectively) (Figure 3b–d).