Coumadin is an anti-platelet medication that helps prevent blood clots. Blood clots in the peripheral extremities would cause edema, and coumadin should prevent any blood clos or at least reduce the formation. The swelling of the feet, etc. indicates there is some blockage of the vessls in question and fluids are leaking into the tissues (edema).
Hope this helps, and thanks for your question. If you have any further quesions or comments you are welcome to respond. Take care,
Ken