paul,

Thanks for your question.

If there is no contraindication to the use of warfarin (Coumadin), you should be taking coumadin for atrial fibrillation.  This is considered "full" anticoagulation and is the most effective oral blood thinner available at this time.  With atrial fibrillation, there is a significant risk of clot formation within the small chamber of the heart, and a piece of this clot may break off and travel to other parts of the body and could cause arterial blockages in the legs, arms, intestines, and the brain (causing a stroke).  Though a hassle, frequent checks of the level of activity of the Coumadin is necessary, as too little of the drug is dangerous, and too much is also dangerous.

Plavix with or without aspirin is not considered full anticoagulation.  These drugs work on the platelets in the bloodstream and make them less sticky and therefore less chance for clot formation.  Though helpful, they are not as effective as Coumadin.  In some cases, patients are unable to take Coumadin, and using Plavix is an alternative, but again, not as effective.

You should also know that trials are underway with a new drug that works like Coumadin and has the same effectiveness, but does not require blood work to monitor levels.

I hope this information has been helpful.

Best wishes.

Martin Cane, M.D.