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CHADS2 is a scoring system for patients with atrial fibrillation to try and determine their risk of stroke,[1] and therefore decide who should be treated with an anticoagulant.[2]

It is an easily applied scoring system and each item scores one point (except for stroke, hence the 2)

giving a maximum score of 6.

The risk of stroke as a percentage per year is:

  • 0—1.9%
  • 1—2.8%
  • 2—4.0%
  • 3—5.9%
  • 4—8.5%
  • 5—12.5%
  • 6—18.2%

As detailed in the respective JAMA and Circulation articles, a score of 0 is classified as low risk; 1-2, moderate risk; 3 or more, high risk. Based on this classification, the following treatment strategies were proposed by the authors:

  • 0—Aspirin (325 mg/day most likely to offer benefit, although lower doses may be similarly efficacious)
  • 1 to 2—Aspirin or Warfarin to INR 2.0-3.0, depending on factors such as patient preference
  • 3 or more—Warfarin to INR 2.0-3.0 unless contraindicated (e.g., history of falls, clinically significant GI bleeding, inability to obtain regular INR screening)

The main criticism of the CHADS2 scoring system is that someone with atrial fibrillation and a previous history of stroke, but no other risk factors, is only classified as moderate risk, whereas that person is in fact at high risk of another stroke.


Patients with a CHA2DS2-VASc of two or more may benefit from chronic anticoagulation according to a recent observational study[3] and American clinical practice guidelines[4]. European clinical practice guidelines recommend anticoagulants if the CHA2DS2-VASc is two or more.[5]


  1. Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. (2001). "Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation". JAMA 285 (22): 2864–70. PMID 11401607.
  2. Gage BF, van Walraven C, Pearce L, et al. (2004). "Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin". Circulation 110 (16): 2287–92. DOI:10.1161/01.CIR.0000145172.55640.93. PMID 15477396. Research Blogging.
  3. Friberg L, Skeppholm M, Terént A (2015). "Benefit of Anticoagulation Unlikely in Patients With Atrial Fibrillation and a CHA2DS2-VASc Score of 1.". J Am Coll Cardiol 65 (3): 225-32. DOI:10.1016/j.jacc.2014.10.052. PMID 25614418. Research Blogging.
  4. January CT, Wann LS, Alpert JS, Calkins H, Cigarroa JE, Cleveland JC et al. (2014). "2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the Heart Rhythm Society.". Circulation 130 (23): 2071-104. DOI:10.1161/CIR.0000000000000040. PMID 24682348. Research Blogging.
  5. Camm AJ, Lip GY, De Caterina R, Savelieva I, Atar D, Hohnloser SH et al. (2012). "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.". Europace 14 (10): 1385-413. DOI:10.1093/europace/eus305. PMID 22923145. Research Blogging.