ARTN and atrial fibrillation: The percentages of 2+ cells of ARTN in the AF (29.8 ± 3.5%) and NP (45.5 ± 4.8%) tissues of the advanced degenerated stage were significantly higher than those in the early degenerated stage AF (15.5 ± 4.9%, p < 0.05) and NP (26.9 ± 3.9%, p < 0.01) tissues (Figure 7b).