Stroke Risk Stratification in Atrial Fibrillation

Annual Stroke Rates by CHA₂DS₂-VASc Score

The European Society of Cardiology provides validated annual thromboembolic event rates for each score category, with a score of 0 having a 0% annual stroke rate, and a score of 9 having an annual stroke rate of over 15% 1, 2, 3
The annual stroke rate for a CHA₂DS₂-VASc score of 1 is 0.6-1.3% per year 1, 2, 3
The annual stroke rate for a CHA₂DS₂-VASc score of 2 is 1.6-2.2% per year, which is the most clinically relevant threshold for oral anticoagulation 1, 2

The European Society of Cardiology recommends oral anticoagulation for patients with a CHA₂DS₂-VASc score of 2 or higher, due to an annual stroke rate of 1.6-2.2% or higher 1, 2
The 1% annual stroke rate threshold traditionally justifies oral anticoagulation initiation, but data shows substantial variability depending on the validation cohort used 3

For patients with a CHA₂DS₂-VASc score of 1, the evidence reveals considerable heterogeneity, with an annual stroke rate of 1.4% (range 0.5-2.9%) per 100 patient-years without anticoagulation, and 0.7% (range 0.1-1.3%) per 100 patient-years with anticoagulation 2, 3
The American College of Cardiology recognizes that women without other risk factors (score = 1 for sex alone) have truly low risk similar to men with a score of 0 4