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See Also

Peripheral Artery Disease: causes and consequences

Coronary Artery Disease: causes and consequences

Preventing AF-Related Stroke

This section covers the epidemiology and demographics of AF, and stroke risk assessment

  • AF affected over 6 million people in the EU, and approximately 5.3 million people in the US in 20091
  • It is anticipated that these figures will rise to between 14–17 million by the year 2030 in the EU2 with projections in the US reaching 12 million by the year 20503
  • The exact epidemiological profile of AF is incomplete and underestimated, because 10-40% of patients with AF (particularly the elderly) can be asymptomatic (referred to as ‘clinically silent or subclinical AF’)4
  • Prevalence increases from 0.7% in those aged 55–59 years to almost 18% in those >85 years of age5
  • The overall prevalence of AF is predicted to at least double in the next 50 years, as a consequence of the ageing population6
  • In AF, the atria beat irregularly and often rapidly, due to an abnormal, fast electrical rhythm in the upper chambers of the heart
  • During AF the upper chambers do not contract fully and in areas the blood flow can become impaired
  • When blood becomes stagnant, the mechanisms that form a clot are activated and a thrombus can form in the fibrillating atria of the heart
  • Thrombus formation most commonly occurs in the LAA, an extension originating from the main body of the left atrium with reduced contractility and stasis, only 10% form in the right atrial appendage7
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An uncommon right atrial appendage thrombus

  • This thrombus can embolize and travel to the brain, blocking arterial blood flow and causing ischaemic stroke
  • Consequently, patients with AF have a fivefold increased risk of stroke8
  • Elderly patients with AF are particularly vulnerable to stroke
    • The prevalence of AF increases with age, and approximately 35% of patients with AF are ≥80 years of age9
  • AF-related strokes are generally more severe and are associated with greater mortality and morbidity than strokes in patients without AF10
  • Stroke in patients with AF results in longer hospital stays and greater healthcare resource use and associated costs than in those without AF11,12

Several risk assessment scoring systems are available to help clinicians estimate the risk of stroke in patients with AF, and guide recommendations for antithrombotic therapy.

  • CHADS2 is a simple, well-validated points-based risk assessment tool widely used to assess individual patient risk for stroke
Stroke risk assessment: CHADS2 score
Classification Risk factor Points
C Congestive heart failure 1
H Hypertenstion 1
A Age ≥75 years 1
D Diabetes mellitus 1
S2 Prior stroke/TIA/thromboembolism 2

Adapted from Gage et al 2001.13


CHADS2 score calculator Accessed date: 29/09/2016

CHADS2 risk assessment does not incorporate a number of documented risk factors for stroke. Patients with a CHADS2 score of 0 are not necessarily at low risk of stroke, and registry data show that anticoagulation decisions simply based on a CHADS2 score of ≥1 may leave many patients at an unacceptable risk of stroke.14

  • The CHA2DS2-VASc score was developed in an effort to improve the predictive value for stroke risk, especially in low-risk patients15
    • CHA2DS2-VASc is now preferred over CHADS2 in the latest ESC 2020 and AHA/ACC/HRS 2019 guidelines8,16
  • CHA2DS2-VASc identifies ‘major’ risk factors, comprising stroke/TIA/thromboembolism and age ≥75 years (2 points each), and ‘clinically relevant non-major’ risk factors, comprising congestive heart failure, hypertension, diabetes mellitus, age 65–74 years, female gender and vascular disease (1 point each)17
Stroke risk assessment: CHA2DS2-VASc score
  Risk factor Points
C Congestive heart failure/left ventricular dysfunction 1
H Hypertension 1
A2 Age ≥75 years 2
D Diabetes mellitus 1
S2 Stroke/TIA/thromboembolism 2
V Vascular disease (prior myocardial infarction, peripheral artery disease, aortic plaque) 1
A Age 65−74 years 1
Sc Sex category (i.e. female gender) 1

Adapted from Lip et al. 2010.17


CHA2DS2-VASc score calculator Accessed date: 29/09/2016

  • Patients with AF and a CHA2DS2-VASc score of ≥2 in men or ≥3 in women are considered to be at high risk of stroke, and NOAC therapy is recommended8,16
  • Patients with AF and a score of 1 in men and 2 in women are at moderate risk of stroke and oral anticoagulation should be considered8,16
  • Patients with AF and a score of 0 in men and 1 in women are at low risk of stroke and do not require antithrombotic therapy8,16

AF management strategies should aim to avoid stroke, manage symptoms and manage cardiovascular risk factors and co-morbidities. It is important to note that approaches intended to restore normal sinus rhythm do not necessarily reduce the risk of stroke in patients with AF. Therefore, even for patients who have undergone successful cardioversion, long-term anticoagulation may be appropriate when the risk of stroke is high.8

Guidelines recommend the use of antithrombotic therapy for stroke prevention in patients with AF based on an individual’s predicted risk of stroke.8,16

Guideline recommendations for stroke prevention in patients with AF
Risk category CHA2DS2-VASc score ESC 20208 AHA/ACC/HRS 201916

Men: ≥2

Women: ≥3

Anticoagulation recommended. NOAC preferred over VKA Anticoagulation recommended. NOAC preferred over VKA
Moderate Men: ≥1
Women: ≥2 
Anticoagulation treatment should be considered. NOAC preferred over VKA Treatment with an anticoagulant may be considered. NOAC preferred over VKA.
Low Men: 0
Women: 1
No antithrombotic therapy No antithrombotic therapy


ACC, American College of Cardiology; AHA, American Heart Association; ESC, European Society of Cardiology; HRS, Heart Rhythm Society


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