GIM Question 17 Instructor

A 78-year-old woman suffers a transient ischemic attack. She is a type 2 diabetic, and has hypertension. There is no history of coronary artery disease. An ECG done in emerge demonstrates atrial fibrillation.

1. Calculate her annual stroke risk.
   The CHADS2 score can be used to evaluate a person’s annual risk of stroke with atrial fibrillation.
   This woman’s annual risk of stroke (without anticoagulation) is 12.5%, corresponding to a CHADS2 score of 5. Points are allocated for the following factors:
   • History of congestive heart failure +1
   • History of hypertension +1
   • Age ≥75 +1
   • History of diabetes +1
   • History of stroke or TIA +2

   CHADS2 Score	% Annual Stroke Risk
   0	1.9
   1	2.8
   2	4.0
   3	5.9
   4	8.5
   5	12.5
   6	18.2

   (Adapted from Gage BF, 2001.)

2. What medications should she be on based on her risk, and for how long?
   Because this patient is in the high-risk of annual stroke, she should be taking either warfarin or a novel oral anticoagulant (NOAC).
   • If starting warfarin, she would require bridging anticoagulation with low molecular weight heparin until her warfarin dose is titrated to an INR of 2.0-3.0.
   • Examples of NOACs include: dabigatran (anti-thrombin), rivaroxaban and apixaban (anti-Xa).

   She should be taking this medication for life, or until the risk of complications outweighs the risk of stroke.

Resources

1. Camm AJ et al. 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, 33:2719-2747.
2. Gage BF et al. Validation of Clinical Classification Schemes for Predicting Stroke. Results From the National Registry of Atrial Fibrillation. Jama. 2001, 285:2864-2870.
3. Lip GY, Nieuwlaat R, Pisters R, Lane DA and 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, 137:263-272.