Patients who received P2Y12 inhibitors in the perioperative period showed a lower frequency of atrial fibrillation (1.5% vs. 8.1%, p = 0.03), any anticoagulant drugs prior to the index stroke (1.5% vs. 9.0%, p = 0.01), and perioperative administration with cilostazol (3.8% vs. 10.8%, p < 0.01), and a higher frequency of CAS (86.3% vs. 42.3%, p < 0.01) and treatment with aspirin during the perioperative period than those who did not receive P2Y12 inhibitors (93.1% vs. 20.7%, p < 0.01). The gene discussed is P2RY12; the disease is atrial fibrillation.