c valvular disease (obstruction of the mitral valve, which controls blood flow from the left atrium to the left ventricle) should be treated with long-term warfarin (Coumadin) anti-coagulant therapy to prevent stroke. However, treatment of non-rheumatic atrial fibrillation (without accompanying mitral valve stenosis or obstruction) is still controversial. These patients have a risk of stroke five times greater than normal. One report from the Boston Area Anti-coagulation Trial for Atrial Fibrillation (BAATAF) on the efficacy of low-dose warfarin in preventing strokes summarized its results. A total of 420 patients with non-rheumatic atrial fibrillation were divided almost equally into warfarin and control groups. The average age of the participants was 68 years and 72% were men. The controls were allowed to take aspirin, also an anti-coagulant. The results suggest that low-dose warfarin was effective in preventing stroke among these patients during a follow-up period of over two years, and that side-effects, including hemorrhage, were few. There was one death from stroke and one from hemorrhage in each group. Two non-fatal strokes occurred in the warfarin group, compared with thirteen in the control group. Eight of the thirteen controls who suffered non-fatal strokes were taking aspirin, most at a dosage of at least 325 mg per day, supporting the view that aspirin is not useful in preventing stroke in this patient population. Advanced age also increased the risk of stroke. Some of the 19 deaths from cardiac causes may have been due to undiagnosed stroke or hemorrhage, but there were also fewer of these events in the warfarin group (N.E. Journal of Medicine, 1990). In my view, this study as well as related conclusions underscore a number of factors. These factors have to do with the efficacy of some treatment based upon the type of stroke patient as well as the type of risk. Advanced age was cited as one causal factor of stroke risk, and...
