Table 1.

5 Risk Stratification Schemes Used to Predict Thromboembolism in Persons With Nonvalvular Atrial Fibrillation^*

Risk Scheme	Low Risk	Intermediate Risk	High Risk
AFI	Age <65 yrs and no risk factors	Age >65 yrs and no other risk factors	Prior ischemic stroke or transient ischemic attack, history of hypertension, history of diabetes mellitus
SPAF	No risk factors	History of hypertension	Prior stroke, women older than 75 yrs, recent clinical heart failure, left ventricular fractional shortening ≤25% on echocardiography
CHADS2†	Score 0	Score 1 to 2	Score 3 to 6
Framingham‡	Score 0 to 7	Score 8 to 15	Score 16 to 31
7th ACCP	Age <65 yrs and no other risk factors	Age 65 to 75 yrs and no other risk factors	Prior ischemic stroke, age >75 yrs, moderate to severe left ventricular dysfunction, history of hypertension, diabetes mellitus

^*The AFI, SPAF, CHADS₂, and Framingham schemes were developed to predict atrial fibrillation–related ischemic stroke, not ischemic stroke plus peripheral embolism.

^†The CHADS₂ index is a point system that assigns 1 point each for Congestive heart failure, Hypertension, Age 75 years or older, and Diabetes mellitus and 2 points for prior Stroke or transient ischemic attack (7).

^‡The Framingham score is a point system based on the following clinical factors: age (0 to 10 points), female gender (6 points), systolic blood pressure (0 to 4 points), diabetesmellitus (5 points), and prior ischemic stroke or transient ischemic attack (6 points) (8).

ACCP = American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy guidelines (9); AFI = Atrial Fibrillation Investigators (2); CHADS₂ = Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, and prior Stroke or transient ischemic attack; SPAF = Stroke Prevention in Atrial Fibrillation (6).