Women With Atrial Fibrillation Face A Higher Risk Of Ischemic Stroke Than Men

Using a sample of 13,559 patients with atrial fibrillation, or rapidirregular contractions of the heart, researchers compared the rates ofischemic stroke between men and women and examined the efficacy andcomplications associated with a common blood thinner, Warfarin. Theirfindings are being reported in the September 20 issue of Circulation.

Warfarin is well known to be effective in reducing the risk ofstroke in persons with atrial fibrillation; however prior studies haveprovided conflicting evidence about whether women with atrialfibrillation have a higher risk for stroke than men when not takingblood thinners. "The research from this study clearly shows that genderplays a role in ischemic stroke risk and occurrence," said lead authorMargaret Fang, MD, MPH, assistant adjunct professor of medicine, andhospitalist at UCSF Medical Center.

The higher incidence of stroke in women not taking Warfarintherapy occurred among women in all stroke-risk-factor categories,including those with prior stroke, hypertension, congestive heartfailure, coronary artery disease and diabetes. Because of thesignificant differences in the rate of stroke between men and women,the study indicates that being a woman is an independent risk factorfor stroke and should be considered when choosing treatment options forwomen with atrial fibrillation.

According to the researchers, atrial fibrillation is the mostcommon cardiac arrhythmia, and a major risk factor for both ischemicstroke and peripheral embolism, an obstruction of the blood supply toan organ. Anticoagulation therapies, such as Warfarin, are well knownto substantially reduce the risk of atrial fibrillation-related strokeand embolism, but also have been shown to increase the risk forhemorrhage. "Because of this increased hemorrhage risk, physicians aresometimes hesitant to prescribe the drug, and some studies have shownthat women are less likely to receive warfarin therapy than men," Fangsaid. "However, we found that women in our study did not sufferbleeding complications related to Warfarin more often than men who wereusing the therapy."

Furthermore, data showed that women may actually benefit morefrom Warfarin because of their higher baseline risk for stroke. "Womenwith atrial fibrillation, particularly those with other risk factorsfor stroke, should be especially encouraged to take Warfarin," Fangadded.

The researchers used data from Kaiser Permanente's AnTicoagulationand Risk Factors In Atrial Fibrillation (ATRIA) Study cohort. The studywas supported by a Public Health Services research grant from theNational Institutes on Aging and the Eliot B. and Edith C. ShoolmanFund of Massachusetts General Hospital.