Randomized Trials of Warfarin for Atrial Fibrillation

The article by Ezekowitz et al. in this issue of the Journal 1 marks the completion of a remarkable set of five contemporaneous randomized trials testing the efficacy of warfarin in the prevention of stroke in patients with nonrheumatic atrial fibrillation.1 2 3 4 5 The trials are noteworthy for the consistency of their results, a feature often lacking in prevention trials. Each trial was stopped early because of the marked efficacy of warfarin in preventing stroke (the Canadian study5 was stopped because of the results of other trials). Although there was no plan at the outset to have five independent trials, experience has demonstrated . . .