CHA₂DS₂-VASc Score for Atrial Fibrillation Stroke Risk

Why did you develop the CHA₂DS₂-VASc Score? Was there a clinical experience that inspired you to create this tool for clinicians?

The availability of Non-Vitamin K Antagonist Oral Anticoagulants (NOACs, previously referred to as new or novel oral anticoagulants, has led to a major change in the landscape for stroke prevention in atrial fibrillation (AF). Clinicians are also getting better at understanding how to manage warfarin, recognizing the importance of the average time in therapeutic range (TTR). New data are also re-emerging on the poor evidence for the efficacy and safety of aspirin for stroke prevention in AF. The older CHADS₂ Score was designed to identify “high risk” patients for warfarin, but many common (and important) stroke risk factors in AF are not included within the CHADS₂. CHA₂DS₂-VASc was developed to be more inclusive of common stroke risk factors/modifiers. Numerous validation studies have shown that CHA₂DS₂-VASc is as good as - or possibly better - than CHADS₂ at predicting high risk patients, but CHA₂DS₂-VASc is certainly best at predicting the “low risk” patients.

What pearls, pitfalls and/or tips do you have for users of the CHA₂DS₂-VASc Score? Are there cases when it has been applied, interpreted, or used inappropriately?

In older guidelines, the focus was to identify AF patients at ‘high risk’ of stroke, to target for warfarin treatment; however, many studies have shown under-use of warfarin amongst such ‘high risk’ patients. In 2014, the AHA/ACC/HRS guidelines recommended used of the CHA₂DS₂-VASc Score as the stroke risk assessment tool of choice.

How best to approach stroke prevention in AF by using the CHA₂DS₂-VASc Score?

In 2012, the European Society of Cardiology (ESC) guidelines recommended a clinical practice shift, to initially focus on the identification of ‘truly low risk’ patients who do not need any antithrombotic therapy. These low risk patients are those CHA₂DS₂-VASc score of 0 (male) or 1 (female). Subsequently, the next step is to offer effective stroke prevention (ie. Oral anticoagulation) to those with ≥1 additional stroke risk factors.

What recommendations do you have for health care providers once they have the CHA₂DS₂-VASc Score result? Are there any adjustments or updates you would make to the score given recent changes in medicine?

Use the approach recommended in the 2012 ESC or NICE guidelines - first step, identify LOW RISK patients, i.e., CHA₂DS₂-VASc score of 0 (males) or 1 (females), who do not need any antithrombotic therapy, Next or subsequent step is to offer effective stroke prevention to all others with 1 or more additional stroke risk factors. As per the NICE guidelines, aspirin should not be used for stroke prevention in AF - it is minimally effective, not safe nor is it cost effective.

Have you found colleagues adjusting who receives which type of anticoagulant based on the CHA₂DS₂-VASc Score rather than the CHADS₂ alone?

Definitely. A CHADS₂ of 0 is NOT low risk, and stroke rate can be as high as 3.2%/year if untreated (Olesen et al, Thromb Haemostat 2012). Using CHA₂DS₂-VASc can further refine stroke risk stratification of those with a CHADS₂ score of 0 to identify those who would still substantially benefit from oral anticoagulation.

Gregory Lip, MD, is the David A. Price-Evans Chair in Cardiovascular Medicine at the University of Liverpool and an honorary consultant cardiologist at Liverpool Heart and Chest Hospital. He is also a researcher in the Aalborg Thrombosis Research Unit at Aalborg University in Denmark. Dr. Lip is one of the world’s leading experts in risk stratification of atrial fibrillation, with his research directly informing the widely-used CHA₂DS₂-Vasc and HAS-BLED Scores.