CXCL8 and atrial fibrillation: Circulating levels of NT-proANP (7705 ± 2701 vs. 5749 ± 2764 pg/mL), proBNP (2.25 ± 1.15 vs. 1.68 ± 0.98 pg/mL), angiopoietin-2 (2803 ± 1428 vs. 2048 ± 973 pg/mL), MMP-2 (81,049 ± 19,689 vs. 69,080 ± 18,387 pg/mL) and syndecan-1 (624 ± 410 vs. 559 ± 233 pg/mL) were significantly higher in the AF group compared to the SR group, whereas interleukin-8 levels were lower in the AF group (3.47 ± 2.85 vs. 4.60 ± 3.79 pg/mL) (Fig. 3A).