To understand anticoagulants, you can start from his indication – atrial fibrillation, atrial fibrillation is the patient’s atria lose normal regular contraction, blood stagnation in the atria, inside the various hemostatic components will be more easily deposited and activated, but these clots are often not strong, once dislodged, they will block other blood vessels causing embolism. As an aside: cerebral embolism is a very aggressive cerebrovascular disease, larger and faster than the general cerebral infarction lesion. Anticoagulants act mainly on clotting factors rather than platelets, and inhibit the clotting process rather than dissolve the already formed clot. Thrombi formed in the arterial system tend to be dominated by platelet activation and aggregation, unlike thrombi in the atrial and venous systems. These drugs inhibit thrombus formation by preventing platelet aggregation to some extent through different mechanisms. Therefore, these drugs have a very weak role in the prevention of stroke in atrial fibrillation, but have an important role in the treatment of arterial thrombotic diseases such as coronary artery disease and cerebral thrombosis.