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CHADS2 scoring system
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  • the long-term risk of stroke in valvular atrial fibrillation (AF) depends on clinical predictors, which are collectively assessed in the CHADS2 scoring scheme, an acronym for Congestive heart failure,hypertension, Age>75, Diabetes mellitus, and prior Stroke (1):

CHADS2 Scoring Scheme

  Condition Points
C Congestive heart failure 1
H Hypertension 1
A Age > 75 years 1
D Diabetes Mellitus 1
S2 Prior Stroke or TIA 2

Annual Stroke Risk with Respect to CHADS 2 Score (1)

CHADS2 Score Stroke Risk % 95% confidence interval
0 1.9 1.2-3.0
1 2.8 2.0-3.8
2 4.0 3.1-5.1
3 5.9 4.6-7.3
4 8.5 6.3-11.1
5 12.5 8.2-17.5
6 18.2 10.5-27.4

Anticoagulation based on the CHADS2 score

Score Risk Anticoagulation Therapy Considerations
0 Low Aspirin or no treatment No antithrombotic therapy (or aspirin)
1 Moderate Aspirin or Warfarin Aspirin daily or raise INR to 2.0-3.0, depending on factors such as patient preference
2 or greater Moderate or High Warfarin Raise INR to 2.0-3.0, unless contraindicated (e.g. clinically significant GI bleeding, inability to obtain regular INR screening)

To complement the CHADS2 score, by the inclusion of additional 'stroke risk modifier' risk factors, the CHA2DS2-VASc score has been proposed (2)

  • these additional 'clinically relevant non-major' stroke risk factors include age 65-74, female gender and vascular disease

  • in the CHA2DS2-VASc score score, 'age 75 and above' also has extra weight, with 2 points

CHA2DS2-VASc score for stroke risk in atrial fibrillation

Feature Score
Congestive Heart Failure 1
Hypertension 1
Age >75 years 2
Age between 65 and 74 years 1
Stroke/TIA/TE 2
Vascular disease (previous MI, peripheral arterial disease or aortic plaque) 1
Diabetes mellitus 1
Female 1

CHA2DS2-VASc score has been used in the European Society of Cardiology guidelines for the management of atrial fibrillation (3)

  • European Society of Cardiology (ESC) guidelines recommend that (3):
    • CHADS2 score of 2 and above
      • oral anticoagulation therapy (OAC, eg. with warfarin(INR2-3) or one of the new OAC drugs, such as dabigatran) should be prescribed
    • CHADS2 score is 0-1, other stroke risk modifiers should be considered:
      • (i) If 2 or more risk factors (essentially a CHA2DS2-VASc score score of 2 or more), OAC is recommended; and
      • (ii) If 1 risk factor (essentially a CHA2DS2-VASc score score=1), antithrombotic therapy with OAC or aspirin (OAC preferred) is recommended, and patient values and preferences should be considered
    • if CHA2DS2-VASc score score=0
      • such patients are 'truly low risk'(4), and thus, the ESC guideline recommendation is to prescribe either aspirin or no antithrombotic therapy, but 'no antithrombotic therapy' is preferred