Should all patients with atrial fibrillation receive warfarin? Evidence from randomized clinical trials

Anticoagulants should be used more widely in patients with atrial fibrillation. Legitimate concerns exist about the risk/benefit ratio in younger patients with no risk factors and in patients over the age of 75 years. Use of lower doses of anticoagulation (potential target range INR of 1.5-2.5) than used heretofore is probably the solution to most of the problems associated with anticoagulation, but conclusive proof of the efficacy of this strategy is needed. Although aspirin may reduce the risk of stroke the effect may be no more than among patients with a similar level of cardiovascular risk factors and in sinus rhythm. As such, aspirin is a valid alternative for patients with atrial fibrillation at a low risk of stroke but should not be used as an excuse to withhold anticoagulants in patients at greater risk. Several larger studies investigating the effects of different intensities of anticoagulation and the use of aspirin-warfarin combinations are underway. Indeed SPAF-III, comparing a combination of low dose warfarin and aspirin with formal anticoagulation has been stopped and reported in March 1996. A summary of the results will appear in the July issue. Identification of the minimum effective dose of warfarin and effective monitoring systems remain a priority.