List of products in the National Drug Code with proprietary name . This medication is used to treat certain types of serious (possibly fatal) irregular heartbeat (such as atrial fibrillation/flutter). It is used to restore normal heart rhythm and maintain a regular, steady heartbeat. Dofetilide is known as an anti-arrhythmic drug. It works by blocking the activity of certain electrical signals in the heart that can cause an irregular heartbeat. Treating an irregular heartbeat can decrease the risk for blood clots, and this effect can reduce your risk of heart attack or stroke.