REPLY
Intensity of Anticoagulation To Prevent Stroke in Patients with Atrial Fibrillation
John V.L. Sheffield, MD, and
Eric B. Larson, MD, MPH
1 March 1998 | Volume 128 Issue 5 | Page 408
IN RESPONSE:
We agree that INRs of 2.0 or greater seem to provide optimal protection against embolic stroke and that the case–control study by Hylek and colleagues [1] demonstrates some protection against embolic stroke in the INR range of 1.6 to 2.0 Although it may be reasonable to target an INR of 2.0 within a range of 1.6 to 2.5 for some patients, we believe that several points must be considered before a less effective level of anticoagulation is accepted for elderly patients, who are also at highest risk for embolic stroke.
According to the results of a physician survey, many favor a less aggressive approach to anticoagulation for patients older than 75 years of age, perhaps because of a belief that all elderly patients have "special risks for bleeding" [2]. In the SPAF (Stroke Prevention in Atrial Fibrillation) III trial, elderly patients (mean age, 71 years) at high risk for stroke were treated with adjusted-dose warfarin (INR, 2.0 to 3.0) without excess hemorrhagic risk [3]. Moreover, major bleeding episodes occur most often at INRs greater than 4.0, well above the therapeutic range [4]. Therefore, we agree with Hylek and colleagues [1] that it may be preferable to put greater effort into tight control of the INR within the range of 2.0 to 3.0 than to accept less protection. In our view, the only patients for whom less anticoagulation may be sensible are those who have established special risks for bleeding.
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Author and Article Information
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University of Washington; Seattle, WA 98195
1. Hylek EM, Skates SJ, Sheehan MA, Singer DE. An analysis of the lowest effective intensity of prophylactic anticoagulation for patients with nonrheumatic atrial fibrillation, N Engl J Med. 1996; 335:540-6.
2. McCrory DC, Matchar DB, Samsa G, Sanders LL, Pritchett EL. Physician attitudes about anticoagulation for nonvalvular atrial fibrillation in the elderly. Arch Intern Med. 1995; 155:277-81.
3. Adjusted-dose warfarin versus low-intensity, fixed-dose warfarin plus aspirin for high-risk patients with atrial fibrillation: stroke prevention in atrial fibrillation III randomized clinical trial. Stroke Prevention in Atrial Fibrillation Investigators. Lancet. 1996; 348:633-8.
4. Optimal oral anticoagulant therapy in patients with nonrheumatic atrial fibrillation and recent cerebral ischemia. The European Atrial Fibrillation Trial Study Group. N Engl J Med. 1995; 333:5-10.
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