Epidemiology shows that the risk for stroke in women is about double that in men, which is why gender was added as a risk factor in CHA₂DS₂-VASc. [47] Possible factors that may explain this increased risk are shown in the Figure and include: 

• more severe endothelial dysfunction
• greater levels of prothrombotic compounds such as hormonal factors
• lesser treatment of comorbidities (vascular disease, serum lipid abnormalities)
• lesser pursuit of sinus rhythm because of concerns for risk of (e.g.) torsade de pointes with antiarrhythmic drugs
• women with AFib tend to be older than men with AFib
• under-use of anticoagulation in women due to fears about anticoagulants in older age 

There are other factors, perhaps, but the important point is that physicians must be aware of this differential in risk according to the gender of the patient.

Reiffel JA. Am J Med 2013; 126: 00-00.