May 31st, 2012

Women at Increased Risk for Stroke in Atrial Fibrillation

Among patients with atrial fibrillation (AF), women have a higher risk than men of having a stroke, according to a new study published in BMJ. The increased risk was mostly found in women over 65 years of age and in women with multiple risk factors.

Leif Friberg and colleagues analyzed data from more than 100,000 Swedish patients with AF. Women had a 47% higher rate of ischemic stroke than men (6.2% vs. 4.2% per year, P<0.0001). After adjusting for multiple risk factors, women still had an increased risk (HR 1.18, CI 1.12 – 1.24). Women with CHA2DS2-VASc scores of 2 or less had no increased risk of stroke and there was no significant difference (p=0.09) in women under 65 years of age with no vascular disease.

The authors noted that women are less likely to receive intensive anticoagulation therapy than men after a stroke or MI, but adjusting for this difference did not substantially alter the result. They write that when the decision “to give anticoagulation treatment” is unclear, “we suggest that female sex should probably tip the scale towards initiating treatment.”

In an accompanying editorial, Eva Prescott writes that a “major concern” in this observational study “is the selection of patients to be included and why they were given anticoagulants.” She concludes that women are at increased risk for stroke, “but when differences in age and risk factor profile are taken into account the excess risk is low.” She agrees with the authors that women under 65 years of age with no other risk factors do not require anticoagulation.

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