How is the risk of stroke stratified in patients with atrial fibrillation (AF)?

Updated: Dec 18, 2018
  • Author: Salvador Cruz-Flores, MD, MPH, FAHA, FCCM, FAAN, FACP, FANA; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Answer

Several risk stratification schemes have been created for primary and secondary prevention of ischemic stroke in patients with atrial fibrillation. The table below summarizes the risk stratification according to 4 widely used schemes.

Table 1. Risk stratification according to the most widely used schemes (Open Table in a new window)

Scheme

Low risk

Moderate risk

High risk

AFI

Age < 65 and no other risk factors

Age >65 and no other risk factors

-Previous stroke or TIA

-Diabetes

-Hypertension

ACCP

Age < 65 and no risk factors

Age 65-75 and no other risk factors

-Age >75

-Previous stroke/TIA

-Diabetes

-Hypertension

-Moderate to severe LV systolic dysfunction

CHADS2

Score 0

Score 1-2

Score 3-6

NICE

Age < 65 and no risk factors

-Age ≥65 and no risk factors

-Age < 75 plus hypertension, diabetes, or vascular disease

-Previous stroke/TIA or thromboembolic event

-Age >75 and hypertension, diabetes, or vascular disease

-Heart failure or LV dysfunction or valvular heart disease

AFI: Atrial Fibrillation Investigators [16] ; ACCP: American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy [17] ; CHADS2: Congestive heart failure, Hypertension, Age ≥75, Diabetes, Stroke/TIA [18] ; NICE: National Institute for Health and Clinical Excellence [19]

Of these schemes, the CHADS2 score is most widely used. The score has 5 components: recent heart failure, hypertension, age ≥75 years, and diabetes (each of which accounts for 1 point) and prior stroke/TIA (which accounts for 2 points). The total score ranges from 0-6. The table below shows how the CHADS2 score quantifies the risk of stroke for patients with atrial fibrillation.

Table 2. Quantifying the risk of stroke in patients with atrial fibrillation using CHADS2 score (Open Table in a new window)

CHADS2 score

No. of patients (n=1733)

No. of stroke (n=94)

NRAF crude stroke rate per 100 patient-years

NRAF adjusted stroke rate (95% CI)

0

120

2

1.2

1.9 (1.2-3.0)

1

463

17

2.8

2.8 (2.0-3.8)

2

523

23

3.6

4.0 (3.1-5.1)

3

337

25

6.4

5.9 (4.6-7.3)

4

220

19

8.0

8.5 (6.3-11.1)

5

65

6

7.7

12.5 (8.2-17.5)

6

5

2

44.0

18.2 (10.5-27.4)

NRAF: National Registry of Atrial Fibrillation [18]

A prospective study of patients with atrial fibrillation who were treated with long-term oral anticoagulation was conducted by Poli et al to evaluate the agreement of predictive ability and correlation with adverse events among the 4 widely used schemes (AFI, ACCP, CHADS2, and NICE), and the results showed that for primary stroke prevention, the CHADS2 and NICE scores had the best predictive accuracy. [20] However, for secondary stroke prevention, the risk stratification is not needed, and oral anticoagulant should be the treatment of choice.


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