The pathophysiology of AF development in the postoperative period is thought to be complex, consisting of several clinical and perioperative factors such as older age, male sex, past medical history of heart failure, chronic obstructive pulmonary disease, chronic kidney disease, diabetes mellitus, metabolic syndrome, obesity, high levels of brain natriuretic peptide, severe coronary artery disease, increased LA dimension, anemia, and blood transfusion preceding the surgery [18,19]. The gene discussed is NPPB; the disease is anemia.