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Prevention of thromboembolism in atrial fibrillation

A meta-analysis of trials of anticoagulants and antiplatelet drugs

  • Clinical Review
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Abstract

OBJECTIVE: Appropriate use of drugs to prevent thromboembolism in patients with atrial fibrillation (AF) involves comparing the patient’s risk of stroke and risk of hemorrhage. This review summarizes the evidence regarding the efficacy of these medications.

METHODS: We conducted a meta-analysis of randomized controlled trials of drugs used to prevent thromboembolism in adults with nonpostoperative AF. Articles were identified through the Cochrane Collaboration’s CENTRAL database and MEDLINE until May 1998.

MAIN RESULTS: Eleven articles met criteria for inclusion in this review. Warfarin was more efficacious than placebo for primary stroke prevention (aggregate odds ratio [OR] of stroke =0.30, 95% confidence interval [CI] 0.19, 0.48), with moderate evidence of more major bleeding (OR 1.90; 95% CI 0.89, 4.04). Aspirin was inconclusively more efficacious than placebo for stroke prevention (OR 0.56, 95% CI 0.19, 1.65), with inconclusive evidence regarding more major bleeds (OR 0.81, 95% CI 0.37, 1.77). For primary prevention, assuming a baseline risk of 45 strokes per 1,000 patient-years, warfarin could prevent 30 strokes at the expense of only 6 additional major bleeds. Aspirin could prevent 17 strokes, without increasing major hemorrhage. In direct comparison, there was evidence suggesting fewer strokes among patients on warfarin than among patients on aspirin (aggregate OR 0.64, 95% CI 0.43, 0.96), with only suggestive evidence for more major hemorrhage (OR 1.60, 95% CI 0.77, 3.35). However, in younger patients, with a mean age of 65 years, the absolute reduction in stroke rate with warfarin compared with aspirin was low (5.5 per 1,000 person-years) compared with an older group (15 per 1,000 person-years).

CONCLUSION: In general, the evidence strongly supports warfarin for patients with AF at average or greater risk of stroke. Aspirin may prove to be useful in subgroups with a low risk of stroke, although this is not definitively supported by the evidence.

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Author information

Authors and Affiliations

  1. Received from the Division of General Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, Md

    Jodi B. Segal MD, MPH, Nina Kim MS, Neil R. Powe MD, MPH, MBA, Karen A. Robinson MSc & Eric B. Bass MD, MPH

  2. Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Md

    Robert L. McNamara MD, MHS

  3. Division of Pediatric Cardiology, Johns Hopkins University School of Medicine, Baltimore, Md

    Marlene R. Miller MD

  4. Oncology Center-Division of Biostatistics, Johns Hopkins University School of Medicine, Baltimore, Md

    Steven N. Goodman MD, PhD

  5. Department of Epidemiology, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Md

    Robert L. McNamara MD, MHS & Neil R. Powe MD, MPH, MBA

  6. Baltimore Cochrane Center at University of Maryland, University of Maryland School of Medicine, Baltimore, Md

    Nina Kim MS & Karen A. Robinson MSc

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  1. Jodi B. Segal MD, MPH
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  2. Robert L. McNamara MD, MHS
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  3. Marlene R. Miller MD
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  8. Eric B. Bass MD, MPH
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the Johns Hopkins Evidence-based Practice Center

Corresponding author

Correspondence to Jodi B. Segal MD, MPH.

Additional information

Presented as an oral presentation to the Society for General Internal Medicine, San Francisco, Calif, April 1999.

This study was conducted by the Johns Hopkins Evidence-B6666ased Practice Center through contract 290-97-006 from the Agency for Health Care Policy and Research, Rockville, Md.

The authors are responsible for the content of this article, including any treatment recommendations. No statement in this article should be construed as an official position of the Agency for Health Care Policy Research or the U.S. Department of Health and Human Services.

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Segal, J.B., McNamara, R.L., Miller, M.R. et al. Prevention of thromboembolism in atrial fibrillation. J GEN INTERN MED 15, 56–67 (2000). https://doi.org/10.1046/j.1525-1497.2000.04329.x

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  • DOI: https://doi.org/10.1046/j.1525-1497.2000.04329.x

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