I suffer from atrial fibrillation due to damage caused to the mitral valve as a result of having rheumatic fever in my teen years. I never experienced the fibrillation until about age 60 although I did have the back flow leakage. During all those prior years I took two 300 grain aspirin daily. I was not instructed to do so by my Dr., although he knew that I did. After the fibrillation onset I was prescribed coumadin, which I took for about 90 days---suffering headache and backache daily as a side effect. I took myself off the medication and went back to aspirin--1 300 grain daily. I informed my Dr. and he said--(my words) " I have read quite a bit on the benefits of the blood thinners and it has not been proven that they are that much more, if any, effective over aspirin".( I am taking .250 mg Lanoxin, daily. That was 12 years ago. I am,for my age, quite physically active though I do not use weights, etc. I make myself stay active with some kind of physical make do work. ( I live in a rural setting). 80 lbs of sacrete ready mix cement is more difficult to handle these days but I can still lift it--just not as rapidly. I have had the stress tests done and the Heart man gets awfully excited when my pulse rate exceeds 170 and I can still walk and he says" you need to be on coumadin". He tells my Dr. and we decide that the aspirin is doing a good job. thats my story-its true.