Anticoagulation in cardiac disease significantly improves the prognosis of cardiac patients, and postoperative monitoring of anticoagulation is necessary. Mechanical valves: Hemodynamic improvement after implantation of a mechanical valve is achieved, but the chance of thrombosis is higher and lifelong anticoagulation is usually required. However, regardless of the anticoagulant used, there is no guarantee against embolism and concomitant bleeding. Anticoagulation strategy: lifelong anticoagulation. In general patients, warfarin alone can be used to maintain an international normalized ratio (INR) of prothrombin time between 1.8 and 3.0. If anticoagulation is followed by embolism, aspirin 80 to 160 mg/day, or clopidogrel 75 mg/day, or dipyridamole 200 mg/day may be added. Biological flap: Although the incidence of thrombosis is reduced, there is still a possibility of thromboembolism. Anticoagulation strategy: low-intensity anticoagulation for 3 months postoperatively. If no history of embolism, heart failure, atrial fibrillation, left atrial enlargement. Aspirin alone may be used.