The beat goes on

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: Prior ischemic stroke, transient ischemic attack, systemic embolism Age >75 y Moderate or severe left ventricular systolic dysfunction or congestive heart failure	Warfarin^*

Adapted from Chest 2004;126:429S–56S.
ASA—acetylsalicylic acid, INR—international normalized ratio.
↵* Target INR = 2.5 (2.0–3.0).

American College of Chest Physicians’ guidelines for prevention of stroke in patients with atrial fibrillation

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.