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Therapy to Prevent Stroke in Patients with Atrial Fibrillation
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What is the problem and what is known about it so far?
Atrial fibrillation is a kind of irregular heart rhythm. People with atrial fibrillation sometimes develop blood clots in their hearts. These clots can lead to stroke if the blood clots travel from the heart to the brain. Strokes are the neurologic problems, such as weakness or difficulty with speech, that result when brain tissue does not get enough blood. Antithrombotic medicines like warfarin or aspirin make the blood take longer to clot. These medicines can therefore prevent stroke in many people with atrial fibrillation. But doctors are sometimes reluctant to prescribe and patients can be reluctant to take these medications because they can lead to bleeding complications like bleeding ulcers or bleeding into the brain.
Why did the researchers do this particular study?
In recent years, different researchers have conducted 16 separate studies of antithrombotic medications for atrial fibrillation. The present researchers combined the data from these previous studies to better estimate the ability of these medications to prevent stroke and their likelihood of causing bleeding complications for patients with atrial fibrillation.
Who was studied?
In the 16 studies that were analyzed, there were a total of 9874 patients.
How was the study done?
Using computers, the researchers searched the medical literature to identify all studies of antithrombotic medications to prevent stroke for patients with atrial fibrillation. They included only randomized, controlled trials where patients received warfarin, aspirin, or no treatment. In a randomized, controlled trial, each patient has an equal chance of receiving one of the treatments. Studies are designed like this when it really is not clear that one treatment is better than another or better than no treatment at all. Using a statistical method called meta-analysis, the researchers combined the findings of the 16 separate studies.
What did the researchers find?
Warfarin and aspirin reduced the chances of stroke for patients with atrial fibrillation. Warfarin prevented more strokes than aspirin. Major bleeding complications did not outweigh these benefits.
What were the limitations of the study?
Combining the results of separate studies can be misleading, especially if the studies are very different from each other.
What are the implications of the study?
Physicians should prescribe antithrombotic medications to most patients with atrial fibrillation, except when particular patients have conditions that put them at high risk for bleeding complications. The choice between warfarin and aspirin depends on the inherent risk for stroke: Patients with atrial fibrillation who have the highest stroke risk benefit most from warfarin.
Article and Author Information
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The summary below is from the full report titled “Antithrombotic Therapy To Prevent Stroke in Patients with Atrial Fibrillation: A Meta-Analysis.” It is in the 5 October 1999 issue of Annals of Internal Medicine (volume 131, pages 492-501). The authors are R.G. Hart, O. Benavente, R. McBride, and L.A. Pearce.
- Copyright ©2004 by the American College of Physicians
