CHADS2...

CHADS2 is a widely used model for estimating stroke risk in AF.

 It estimates stroke risk in non-rheumatic AF by assigning

1 point each for Congestive heart failure, Hypertension, Age ≥ 75 years, or Diabetes mellitus

and 2 points for history of Stroke or TIA.

For example, an 82-year-old (+1) patient with hypertension (+1) and past stroke (+2) would have a CHADS2 score of 4.

Patients are considered to be at low risk with a score of 0
intermediate risk with a score of 1 or 2
and at high risk with a score 3 or more.

 Of note, a past history of cerebral ischemia without other risk factors gives only 2 points (intermediate risk), yet most experts consider these patients to be at high risk.
The majority of these patients, however, have some other risk factor and a score of at least 3.