There is risk score system for stroke called CHADS -- it stands for 1. Congestive heart
failure, 2. hypertension, 3. age greater than 75, 4. diabetes, 5 stroke
or TIA (mini stroke).
This scoring system is used to determine what you should be on for blood thinners. From the information you mentioned above, you have at least one risk factor. If you only have that one risk, aspirin or coumadin is appropriate for blood thinning. If you have 2 or more risk factors, you should be on coumadin.