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8/22/2000

Evidence Supports Warfarin to Prevent Stroke

Cheryl A. Thompson

The evidence is in: Warfarin is the most cost-effective initial strategy for preventing stroke in high-risk outpatients with first-time atrial fibrillation.

Aspirin comes in first for the low-risk outpatients, says the Evidence-based Practice Center at Johns Hopkins University, Baltimore, in a newly completed report funded by the Agency for Healthcare Quality and Research (AHQR). 

For intermediate-risk patients, the treatment of choice depends on whether warfarin therapy lowers the quality of a patient's life. 

Because of what the expert reviewers termed inconclusive evidence, they did not state whether low-molecular-weight heparin, the antiplatelet drug indobufen, or a combination of low-dose warfarin with aspirin should be used as first-line treatment to prevent stroke. 

The experts systematically reviewed reports on randomized controlled trials of therapies for managing adults with new-onset atrial fibrillation, a condition that can increase a patient's risk for stroke by as much as fivefold. Three aspects of management were investigated: control of the ventricular heart rate, conversion of the fibrillating heart to sinus rhythm and maintenance of that rhythm, and prevention of thromboembolism and subsequent stroke. 

To control the ventricular rate at rest and during exercise, diltiazem or verapamil should be tried first, the experts suggest. Beta-blockers performed better than digoxin in the trials but not as well as diltiazem or verapamil against digoxin. 

The experts found strong evidence supporting the use of flecainide, ibutilide, or dofetilide to convert the heart to sinus rhythm. 

Quinidine, disopyramide, flecainide, propafenone, and sotalol had strong evidence supporting their use to maintain sinus rhythm after conversion from atrial fibrillation. 

A summary of the experts' report, "Management of New Onset Atrial Fibrillation," is available online. AHRQ says the full evidence report will be available by fall 2000. In the meantime, details of the experts' assessment of anticoagulants and antiplatelet drugs can be found in the January issue of the Journal of General Internal Medicine (Segal JB, McNamara RL, Miller MR et al., for the Johns Hopkins Evidence-based Practice Center. Prevention of thromboembolism in atrial fibrillation: a meta-analysis of trials of anticoagulants and antiplatelet drugs. 2000; 15:56-67).