Strong blood thinners such as warfarin or dagabitran are needed if your blood is prone to clotting.
Pulmonary Embolism or DVT
Metal heart valves.
Warfarin requires careful monitoring that your cardiologist or your GP will be able to do. This involves regular blood tests to ensure your are getting enough drug. Too little, and it is not effective, too much and you will get bleeding problems. Do not take any over the counter or prescription medication without discussing it with your doctor- these drugs can interact with warfarin and risk your health. Do not stop warfarin without discussing it with your doctor.
Although often avoided to prevent bleeding problems, aspirin and even clopiodgrel may be prescribed along with warfarin in some circumstances.