To optimize the appropriate use of warfarin, or anticoagulation in general, several risk scores have been developed to calculate the risk of stroke in patients with AFib.[8]  A premier example is CHADS2 risk score, which is an algorithm that assigns index points to different risk factors.  As shown in Figure 9, the letters C-H-A-D-S- stand, respectively, for congestive heart failure, hypertension, age >75 years, diabetes mellitus, and stroke or transient ischemic attack (TIA).[9]  The first four elements are given 1 point, whereas stroke or TIA, conferring the highest risk of a future stroke, is assigned 2 points.  Thus on the CHADS2 score the maximum number of points would be 6 and the minimum would be 0.