The rate of ischemic stroke in patients with atrial fibrillation (AF) untreated with antithrombotic therapy is around 4.5% per year. Guidelines recommend the use of antithrombotic therapy for stroke prevention in AF, but are these medications being prescribed?
A population-based study was conducted within a large nonprofit health maintenance organization based in Seattle. Researchers looked at the medical records of members aged 30 to 84 who were newly diagnosed with AF (572 patients) over a 1-year period. Patients were stratified by risk factors according to the American College of Chest Physicians’ criteria.
RISK | CLINICAL FEATURES | RECOMMENDATION |
---|---|---|
Low | Age <65 y and no other risk factors | ASA (325 mg/d) |
Inter-mediate | Age 65–75 y and no other risk factors | ASA (325 mg/d) or warfarin* |
High | Any risk factor:
| Warfarin* |
Adapted from Chest 2004;126:429S–56S.
ASA—acetylsalicylic acid, INR—international normalized ratio.
↵* Target INR = 2.5 (2.0–3.0).
Over 70% (418/572) had evidence of antithrombotic therapy within 6 months. Most (76%) were at high risk of stroke; however, almost one quarter of this group was not treated. In those who were treated in the high-risk group, 59% were treated with warfarin and 28% with acetylsalicylic acid. The best predictor of warfarin use was AF classification, rather than risk level. Those with intermittent or sustained AF were more likely to be treated than those with transitory AF.
Bottom line
Patients with atrial fibrillation (AF) should be prescribed antithrombotic therapy based on their risk level for stroke, rather than AF classification.
Footnotes
Source: Glazer NL, Dublin S, Smith NL, French B, Jackson LA, Hrachovec JB, et al. Newly detected atrial fibrillation and compliance with antithrombotic guidelines. Arch Intern Med 2007;167(3):246–52.
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