Criteria
American Heart Association (AHA) and European Society of Cardiology (ESC) guidelines emphasize a risk factor-based approach using a validated clinical risk score such as the CHA₂DS₂-VASc score system. The CHA₂DS₂-VASc score is considered the most validated score; however, newer online calculators for risk scores, such as ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation) and GARFIELD (Global Anticoagulant Registry in the Field-Atrial Fibrillation), in comparison to CHA₂DS₂-VASc, may modestly improve discrimination between high versus low risk and may offer potential advantages in specific populations.[1]
CHA₂DS₂-VASc scoring system for risk of thromboembolism[1][2]
2 points each:
History of stroke, transient ischemic attack, or thromboembolism
Age ≥75 years
1 point each:
Age 65-74 years
History of hypertension, diabetes, congestive heart failure, or vascular disease (myocardial infarction, complex aortic plaque, peripheral arterial disease)
Female
[Figure caption and citation for the preceding image starts]: CHA₂DS₂-VASc (congestive heart failure/left ventricular dysfunction, hypertension, age ≥75 years [doubled], diabetes, stroke [doubled], vascular disease, age 65-74 years, sex category [female])Adapted from January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2014 Dec 2;64(21):e1-76 [Citation ends].
According to this scoring system, a score of 0, 1 and ≥2 indicates low, intermediate, and high risk, respectively.
ATRIA[88]
The ATRIA stroke risk model includes age and prior stroke as dominant risk predictors, with possible scores ranging from 7 to 15 for patients who have had a prior stroke, and from 0 to 12 in those with no history of stroke.
Age:
≥85 years scores 6 without prior stroke, 9 with history of stroke
75 to 84 years scores 5 without prior stroke, 7 with history of stroke
65 to 74 years scores 3 without prior stroke, 7 with history of stroke
<65 years scores 0 without prior stroke, 8 with history of stroke
Regardless of stroke history each of the following risk factors scores 1 point each:
Female
Diabetes
Congestive heart failure
Hypertension
Proteinuria
eGFR <45 or end stage renal disease
According to this scoring system, a score of 0-5, 6, and 7-15 indicates low, intermediate, and high risk, respectively.
GARFIELD[89]
The GARFIELD risk calculator assesses future risk of mortality, ischemic stroke and major bleeding to guide use of anticoagulants in patients with a new diagnosis of atrial fibrillation. [ GARFIELD-AF ]
It includes the variables age, history of stroke, bleeding, heart failure, chronic kidney disease, region, ethnicity, anticoagulant use, female sex, history of carotid occlusive disease, dementia, and smoking. According to this scoring system, a score of 0-0.89, 0.9-1.59, and ≥1.6 indicates low, intermediate, and high risk, respectively.
CHADS₂ scoring system for risk of thromboembolism[90]
In patients with AF and nonvalvular (particularly rheumatic) heart disease, the risk of thromboembolic stroke was historically estimated by calculating the CHADS₂ score. The CHADS₂ score system is useful and easy to remember. However, because the risk of thromboembolic events is a continuum, categorization of the risks into low, moderate, and high is artificial, especially taking only a few risk factors into account. The value of the CHADS₂ score system in the risk stratification of patients with AF who undergo direct current cardioversion is not reliable, especially for those patients with a low CHADS₂ score, and it has been replaced by CHA₂DS₂-VASc in guidelines.[91]
The variables are congestive heart failure (C), hypertension (H), age (A), diabetes mellitus (D), and a history of stroke (S). Each variable is given 1 point except the presence of a history of stroke or prior transient ischemic attack, which is given 2 points. The validation of this scheme indicates low risk for a CHADS₂ score of 0, moderate risk for a CHADS₂ score of 1 to 2, and high risk for a CHADS₂ score of >2 for future risk of thromboembolic stroke.
The stroke rate per 100 patients-years without antithrombotic therapy according to CHADS₂ score is as follows:
Score 0: stroke risk 1.9% (95% CI 1.2 to 3.0)
Score 1: stroke risk 2.8% (95% CI 2.0 to 3.8)
Score 2: stroke risk 4.0% (95% CI 3.1 to 5.1)
Score 3: stroke risk 5.9% (95% CI 4.6 to 7.3)
Score 4: stroke risk 8.5% (95% CI 6.3 to 11.1)
Score 5: stroke risk 12.5% (95% CI 8.2 to 17.5)
Score 6: stroke risk 18.2% (95% CI 10.5 to 27.4).
Risk factors for thromboembolism in patients with AF
The American College of Cardiology, AHA, ESC, and the Heart Rhythm Society, and the National Registry of Atrial Fibrillation (NRAF) guidelines described the rationale for using anticoagulation based on risk factors assessed by the CHADS and CHA₂DS₂-VASc scores.[1][92]
As well as guiding the need for treatment in once AF has occurred, the CHADS₂ and CHA₂DS₂-VASc scores are also directly associated with the incidence of new-onset atrial fibrillation.[93]
Less validated or weaker risk factors
Female sex
Age 65-74 years
Coronary artery disease
Thyrotoxicosis.
Moderate risk factors
Age ≥75 years
Hypertension
Heart failure
Left ventricular ejection fraction ≤35%
Diabetes mellitus.
High risk factors
Previous stroke, transient ischemic attack, or embolism
Mitral stenosis
Prosthetic heart valve.
HAS-BLED[94]
HAS-BLED is a scoring system in which the clinical characteristics of hypertension (H), abnormal renal or hepatic function (A), stroke (S), bleeding or its risks (B), labile international normalized ratios (L), older age group (>65 years) (E), and drugs/alcohol (drugs such as antiplatelets) (D) are given 1 point each. Based on this scoring system, the risk of bleeding is significantly higher for scores of ≥3.
HEMORR2HAGES score system[92] HEMORR2HAGES calculator Opens in new window
In addition to consideration of the risk of stroke and benefit of anticoagulation therapy, the risk of hemorrhage (particularly intracranial) has to be considered. For patients taking warfarin, several scoring systems aim to stratify this risk of bleeding. In the HEMORR2HAGES score, points are assigned for each risk factor: hepatic or renal disease (H), ethanol abuse (E), malignancy (M), older age (>75 years) (O), reduced platelet count or function (R), rebleeding risk (R), uncontrolled hypertension (H), anemia (A), genetic factor (G), excessive fall risk (E), and stroke (S). One point is awarded for each risk factor, except for a prior bleed (rebleeding risk), which is given 2 points.
Using this system, the risk of major bleeding in NRAF participants prescribed warfarin, stratified by HEMORR2HAGES score, was as follows.
Bleeds per 100 point-years warfarin:
Score 0: 1.9 (95% CI 0.6 to 4.4)
Score 1: 2.5 (95% CI 1.3 to 4.3)
Score 2: 5.3 (95% CI 3.4 to 8.1)
Score 3: 8.4 (95% CI 4.9 to 13.6)
Score 4: 10.4 (95% CI 5.1 to 18.9)
Score ≥5: 12.3 (95% CI 5.8 to 23.1).
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