CHA2DS2 VASc Score For Stroke Risk In Atrial Fibrillation
Determines risk of stroke and thromboembolic events in patients with atrial fibrillation.
Information about the score interpretation and about the original study can be found in the text below the calculator.
The CHA2DS2 VASc score evaluates patients with heart disease (atrial fibrillation) to check whether they are at risk of stroke or other thromboembolic events.
The score is based on patient age, gender and personal history of diseases that are risk factors for TE events.
It provides a percentage of risk and a recommendation as to whether the patient should be started on anticoagulation therapy or not.
The score is based on a study by Lip et al. on a cohort of 1,084 patients with atrial fibrillation and was developed after identifying additional stroke risk factors in patients with AF.
■ Patients who score 0 points (meaning no risk factors) may not require anticoagulation.
■ Patients who score 1 point are considered at low-moderate risk of thromboembolic episodes and might require either antiplatelet or anticoagulation therapy.
■ Patients who score 2 or more points are at high risk and should have anticoagulation initiated.
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CHA2DS2 Vasc explained
This is a risk stratifying tool that evaluates patients with non-valvular atrial fibrillation (who are not under anticoagulation therapy) in terms of medical history, to determine whether they are at risk of suffering from a thromboembolic event, here defined as stroke, TIA or systemic embolism.
The 7 items in the score are summarized in the table below:
| CHA2DS2 Vasc | Description |
| Patient age | There are three age groups (below 65, between 65 & 74 and above 75). Risk of stroke is deemed proportional to age increase. |
| Patient gender | This accounts for a higher stroke risk in female patients. |
| Congestive heart failure history | Main risk factor as CHD impairs heart pump function and may lead to ischemic events. |
| Hypertension history | Personal or family history of high blood pressure, with systolic blood pressure above 140 mmHg. |
| Diabetes mellitus history | Diabetes treated here as risk factor for heart disease. |
| Stroke or TIA symptoms previously | Patient will be at higher risk if not under treatment. |
| Vascular disease history | Atherosclerosis is amongst stroke risk factors. |
The CHA2DS2-VASc score is an improved version of the CHADS2 score. The Vasc version accounts for three more variables and tends to classify more patients in the high risk score groups. There is a similar performance to both versions and the choice to use either remains for the clinicians to make.
Score interpretation
The CHA2DS2 Vasc provides a numeric score (depending on the risk factors present and their weight) which is then interpreted in terms of possibility of a future thromboembolic event.
Risk of stroke, transient ischemic attack or systemic embolism is provided as percentage.
The table below introduces the possible scores and their associated risks:
| CHA2DS2 | Risk group | Stroke risk | TIA/Systemic embolism |
| 0 | Low | 0.20% | 0.78% |
| 1 | Low - Moderate | 0.60% | 2% |
| 2 | Moderate - High | 2.20% | 3.70% |
| 3 | High | 3.20% | 5.90% |
| 4 | High | 4.80% | 9.30% |
| 5 | High | 7.20% | 15.30% |
| 6 | High | 9.70% | 19.70% |
| 7 | High | 11.20% | 21.50% |
| 8 | High | 10.80% | 22.40% |
| 9 | High | 12.20% | 23.60% |
There is a proportional relationship between score increase and risk increase of TE events within a year, in patients diagnosed with non-valvular AF and who are not taking anticoagulants.
In terms of prevention recommendation, patients in the low risk group (0 points) are unlikely to require anticoagulation.
Patients in the low-moderate risk group (1 point) may or may not require antiplatelet or anticoagulation whilst patients in the moderate-high and high risk groups (2 and above points) should be started on anticoagulation therapy.
About the study
Lip et al. devised the Birmingham 2009 schema / CHA(2)DS(2)-VASc as a risk stratification tool that addresses shortfalls of other tools that were mainly derived from risk factors identified from trial cohorts, thus not including all potentially relevant risk factors.
The study refined the 2006 Birmingham/National Institute for Health and Clinical Excellence (NICE) stroke risk stratification schema and introduced new risk factors. The performance of the new tool was compared to that of others in a cohort of 1,084 patients diagnosed with AF.
Here are some findings from the study:
■ CHA2DS2 Vasc classified 75.7% of patients in the high risk group, 15.1% in the intermediate risk and 9.2% in the low risk group.
■ In comparison, Framingham score only classified 10.2% of patients as high risk and 48.3% as low risk.
■ The classic CHADS2 categorized most patients, 61.9% in the intermediate risk group.
■ Calculated C-statistics found that all schema have a modest predictive value for thromboembolic events.
■ TE events occurred in 1.4% of patients deemed low risk by the classic CHADS2 but no TE events occurred in all patients classed as low risk by CHA2DS2 Vasc or NICE.
The study concluded that the improved approach with more risk factors provides a more accurate prediction of TE events risk and could improve stratification of patients with atrial fibrillation.
Original source
Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest. 2010; 137(2):263-72.
Validation
Friberg L, Rosenqvist M, Gregory Y.H. Lip Evaluation of risk stratification schemes for ischaemic stroke and bleeding in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort study. European Heart Journal. 2012; 1500-1510
Other references
1. Ntaios G, Lip GY, Makaritsis K, Papavasileiou V, Vemmou A, Koroboki E, Savvari P, Manios E, Milionis H, Vemmos K. CHADS₂, CHA₂S₂DS₂-VASc, and long-term stroke outcome in patients without atrial fibrillation. Neurology. 2013; 80(11):1009-17.
2. Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH, Hindricks G, Kirchhof P; ESC Committee for Practice Guidelines (CPG). 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J. 2012; 33(21):2719-47.
Specialty: Cardiology
System: Cardiovascular
Objective: Risk Prediction
Type: Score
No. Of Items: 7
Year Of Study: 2010
Abbreviation: CHA2DS2 VASc
Article By: Denise Nedea
Published On: June 19, 2017 · 07:52 AM
Last Checked: June 19, 2017
Next Review: June 19, 2023