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Use this calculator to calculate CHADS2 score and risk of stroke in atrial fibrillation.

Heart Failure or Ejection Fraction ≤35%
Stroke, TIA or Systemic Emboli

About this calculator

Warfarin anticoagulation titrated to an INR of 2.0-3.0 is recommended for the average patient with a CHADS2 score ≥2 unless contraindicated (e.g., history of frequent falls, clinically significant bleeding, inability to obtain regular INR).  Either Warfarin or Aspirin can be used for the average patient with a CHADS2 score of 1 depending on physician discretion and patient preference.  Aspirin 325 mg daily is recommended for the average patient with a CHADS2 score of 0.


QxMD Cardiology contributing author: Dr. Jason Andrade, MD, FRCP(C)


Gage BF, van Walraven C, Pearce L, Hart RG, Koudstaal PJ, Boode BS, Petersen P. Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin. Circulation. 2004 Oct 19;110(16):2287-92. PMID: 15477396.
Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA. 2001 Jun 13;285(22):2864-70. PMID: 11401607.
Go AS, Hylek EM, Chang Y, Phillips KA, Henault LE, Capra AM, Jensvold NG, Selby JV, Singer DE. Anticoagulation therapy for stroke prevention in atrial fibrillation: how well do randomized trials translate into clinical practice? JAMA. 2003 Nov 26;290(20):2685-92. PMID: 14645310.