CHA₂DS₂-VASc Score for Atrial Fibrillation Stroke Risk
Why Use
Facilitates the annual stratification of TE and ischemic stroke risk in patients with non-valvular AF.
When to Use
One of several risk stratification schemata that can help determine the one-year risk of a thromboembolic (TE) event in a non-anticoagulated patient with non-valvular atrial fibrillation (AF) without any history of valvular surgery. Can be used in discussions with patients to facilitate shared decision-making regarding their risk for TE events.
Formula
Pearls / Pitfalls
Of the 1577 patients that fulfilled the inclusion criteria, outcome information was missing for 31%, who were excluded from the analysis. These patients could have had TE events, causing them to be lost to follow-up. Although the derivation study found no statistically significant difference between the CHA₂DS₂-VASc and CHADS₂ risk stratification schemata in predicting TE events, subsequent validation studies (e.g., Friberg 2012 and Olesen 2011 ) have found CHA₂DS₂-VASc to be significantly superior to CHADS₂ in performance. CHA₂DS₂-VASc has also demonstrated very high negative predictive values in multiple validation studies. None of the included patients were anticoagulated. Those at particularly high risk for a TE event may have been already anticoagulated by their primary care physician, potentially skewing the TE rates. A subsequent study identified CAD and smoking as potential additional risk factors for TE. However, that study did not show a statistical difference in the predictive risk stratification abilities of the scores. Subsequent research suggests that the only “truly low risk” (i.e., 1-year risk of TE <1%) patients are males with a score of 0, or females with a score of 1, and that the default position should be one of anticoagulation. The risks of paroxysmal AF and permanent AF are similar, and anticoagulation decisions should not be based on whether AF is permanent or paroxysmal. For patients with hypertrophic cardiomyopathy or cardiac amyloidosis, the 2024 European Society of Cardiology guidelines do not recommend basing stroke prevention strategies on the CHA₂DS₂-VASc Score. Presence of other thrombotic risk factors (e.g., impaired renal function) may adversely impact the performance of this score. Interpretation of this score in such patients should be made with caution and with consideration of individual clinical contexts.
Management
Most guidelines suggest that scores of 0 (men) or 1 (women) do not require treatment; however, all other patients should receive anticoagulation, preferably with a direct oral anticoagulant (unless contraindicated). Anticoagulation is not recommended in patients with non-valvular AF and a CHA₂DS₂-VASc score of 0 if male or 1 if female, as these patients had no TE events in the original study. Depending on a patient’s preferences and individual risk factors, anticoagulation can be considered for a CHA₂DS₂-VASc score of 1 in males and 2 in females. Anticoagulation should be started in patients with a CHA₂DS₂-VASc score of ≥ 2 if male or ≥ 3 if female. For those patients in whom anticoagulation is considered, bleeding risk scores such as ATRIA can be used to determine the risk for warfarin-associated hemorrhage. However, these should usually be used as a reminder to regularly address reversible risk factors for bleeding, as the risk-benefit ratio of anticoagulation usually remains favorable. Carefully consider all the risks and benefits prior to initiating anticoagulation in patients with non-valvular AF. Aspirin monotherapy is not supported by current evidence.
Critical Actions
Before initiating anticoagulation, assess the patient’s bleeding risk using validated tools (e.g., HAS-BLED ) and consider concomitant risk factors for bleeding. Weigh the risks and benefits carefully, and discuss them thoroughly with the patient for shared decision-making.
Advice
Recent guidelines emphasize the strong evidence of benefit with anticoagulation and the lack of benefit from antiplatelet treatment. There has been recent work suggesting that sex as a risk factor should be removed from CHA₂DS₂-VASc. Please see the Evidence section for more information.
More Information
Interpretation: CHA₂DS₂-VASc Score Risk of ischemic stroke Risk of stroke/TIA/systemic embolism 0 0.2% 0.3% 1 0.6% 0.9% 2 2.2% 2.9% 3 3.2% 4.6% 4 4.8% 6.7% 5 7.2% 10.0% 6 9.7% 13.6% 7 11.2% 15.7% 8 10.8% 15.2% 9 12.2% 17.4% From Friberg 2012 . Note the paradoxical decrease in risk between 7 and 8 points; this reflects the findings published in the study, but in general, assume increasing risk with higher scores.