It was found that in patients with AF and the presence of MS, the concentration of galectin-3 in the serum is higher than in patients with AF without MS (10.3 (4.8–15.4) and 6.8 (5.2–8.1) ng/mL, p = 0.0001; Figure 1). This evidence concerns the gene LGALS3 and myeloid sarcoma.