REPLY
Antithrombotic Therapy To Prevent Stroke in Patients with Atrial Fibrillation
Robert G. Hart, MD, and
Lesly A. Pearce, MS
16 May 2000 | Volume 132 Issue 10 | Pages 841-842
IN RESPONSE:
Thanks to Dr. Singer for pointing out a misleading heading in Table 2 of our meta-analysis: "Control group" was inadvertently changed to "placebo group" in the process of revision.
Dr. Singer's lack of enthusiasm for aspirin use in atrial fibrillation is long-standing and often voiced (1, 2). His current concerns appear based on post hoc exploratory subgroup analyses of SPAF I, which are not relevant to our meta-analysis. To date, all six randomized trials (five of them double-blind) have shown trends toward reduction in stroke with aspirin use in patients with atrial fibrillation (see the Figure in our meta-analysis). Furthermore, randomized trials comparing warfarin with aspirin have consistently shown a smaller magnitude of stroke reduction than seen in trials comparing warfarin with control or placebo. In short, it seems overwhelmingly likely that aspirin provides some protection against stroke in atrial fibrillation, but the efficacy is clearly much less than that provided by adjusted-dose warfarin, particularly when considering disabling cardioembolic strokes.
It is also clear that many patients with atrial fibrillation who are treated with aspirin have low rates of stroke (whether in part due to or, per Dr. Singer, despite aspirin use) and would not benefit substantially from alternative treatment with warfarin (3-5). The salient clinical issue for the next millennium is not whether aspirin works in atrial fibrillation (it does, but only a little) but rather how to reliably identify individual patients with atrial fibrillation who have relatively low risks for stroke during aspirin therapy and who might not choose anticoagulation once the modest benefits, risks, and disutility are made clear (5).
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Author and Article Information
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University of Texas; San Antonio, TX 78284 (Hart)
Axio Research Corp.; Seattle, WA 98121 (Pearce)
1. Singer DE, Hughes RA, Gress DR. The effect of aspirin on the risk of stroke in patients with nonrheumatic atrial fibrillation: the BAATAF Study Am Heart J. 1992;124:1567-73.[Medline]
2. Singer DE. Aspirin and prevention [Letter] Lancet. 1994;343:233-4.
3. Gullov AL, Koefoed BG, Petersen P, Pedersen TS, Andersen ED, Godtfredsen J, et al. Fixed mini-dose warfarin and aspirin alone and in combination vs. adjusted-dose warfarin for stroke prevention in atrial fibrillation: Second Copenhagen Atrial Fibrillation, Aspirin, and Anticoagulation Study Arch Intern Med. 1998;158:1513-21.[Abstract/Free Full Text]
4. Hellemons BS, Langenberg M, Lodder J, Vermeer F, Schouten HJ, Lemmens T, et al. Primary prevention of arterial thromboembolism in nonrheumatic atrial fibrillation in primary care: randomised controlled trial comparing two intensities of coumarin with aspirin BMJ. 1999;319:958-64.[Abstract/Free Full Text]
5. The SPAF III Writing Committee for the Stroke Prevention in Atrial Fibrillation Investigators. Patients with nonvalvular atrial fibrillation at low risk of stroke during treatment with aspirin JAMA. 1998;279:1273-7.[Abstract/Free Full Text]
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