Anticoagulation medicines; also known as blood thinners; prevent or treat blood clots. Your doctor may prescribe them if you have had a heart attack or if you have an irregular heartbeat (arrhythmia), heart valve disease or another heart and vascular condition. When doctors use medicine to treat you; as opposed to other treatments like surgery or radiation therapy; it is called pharmacotherapy. Anticoagulation therapy is a type of pharmacotherapy.