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Preventing AF-Related Stroke
This section covers the epidemiology and demographics of AF, and stroke risk assessment
In this section:
- AF is the most common sustained cardiac arrhythmia seen in clinical practice
- AF is primarily a condition of the elderly
- AF as a major risk factor for stroke
- The burden of AF-related stroke is well characterized
- Stroke risk assessment is an essential part of AF management strategies
- CHA2DS2-VASc score has improved predictive value in assessment of stroke risk
- CHADS2 and CHA2DS2-VASc scores
- Prevention of thromboembolism and stroke is an important goal in treating patients with AF
- Guideline recommendations
AF is the most common sustained cardiac arrhythmia seen in clinical practice
- AF affected over 6 million people in the EU,1 and approximately 5.3 million people in the US in 20092
- It is anticipated that these figures will rise to between 14–17 million by the year 2030 in the EU3 with projections in the US reaching 12 million by the year 20504
- 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’)5
AF is primarily a condition of the elderly
AF is a major risk factor for stroke
- 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 appendage8
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 an increased risk of stroke9
- 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
The burden of AF-related stroke is well characterized
Stroke risk assessment is an essential part of AF management strategies
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
| 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
CHA2DS2-VASc score has improved predictive value in assessment of stroke risk
CHADS2 risk assessment does not incorporate a number of documented risk factors for stroke.
- The CHA2DS2-VASc score was developed in an effort to improve the predictive value for stroke risk, especially in low-risk patients14
- 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)15
| 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. 2010.15
CHADS2 and CHA2DS2-VASc scores
- Score of ≥2
- Score of 1
- Patients with a score of 1 are at moderate risk of stroke, unless they are female patients with a CHA2DS2-VASc-score of 1 by virtue of gender alone, in which case they should be classified as low risk3
- Guidelines vary in their recommendations for antithrombotic therapy for patients with moderate stroke risk
- Score of 0
- Patients with a CHA2DS2-VASc score of 0 are at low risk of stroke and do not require antithrombotic therapy3
- Traditionally, patients with a CHADS2 score of 0 have also been considered to be at low risk of stroke. However, these patients may have a CHA2DS2-VASc score of between 0 and 3 (if they are female, aged 65–75 and have vascular disease)
- Registry data show that the non-anticoagulated stroke rate in patients with a CHADS2 score of 0 can range from 0.8%/year (CHA2DS2-VASc score=0) to 3.2%/year (CHA2DS2-VASc score=3) after 1 year of follow-up.16 Thus patients with a CHADS2 score of 0 are not necessarily at low risk of stroke, and anticoagulation decisions simply based on a CHADS2 score of ≥1 may leave many patients at an unacceptable risk of stroke
Prevention of thromboembolism and stroke is an important goal in treating patients with AF
AF management strategies should aim to relieve symptoms (when present), optimize cardiac function, and minimize the risk of stroke. 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, lifelong anticoagulation may be appropriate when the risk of stroke or recurrent AF is high.3
Guideline recommendations
Guidelines recommend the use of antithrombotic therapy for stroke prevention in patients with AF based on an individual’s predicted risk of stroke.3,9,17
| Risk category | CHADS2 score | CHA2DS2-VASc score | ESC 20163 | AHA/ACC/HRS 20149 |
|---|---|---|---|---|
| High | ≥2 | ≥2a,b | NOACc | NOAC |
| Moderate | 1 | 1d | NOAC should be considered based upon an assessment of individual characteristics and patient preferencesdd,e | No antithrombotic therapy or treatment with a NOAC or ASA may be considered |
| Low | 0 | 0 | No antithrombotic therapy | No antithrombotic therapy |
aOne ‘major’ risk factor or ≥2 ‘clinically relevant non-major’ risk factors; bCHA2DS2-VASc score of ≥2 in males and ≥3 in females is considered high risk according to ESC guidelines; cNOACs are recommended in preference to VKA therapy; done ‘clinically relevant non-major’ risk factor; efemale patients who are aged <65 years and have lone AF (but still have a CHA2DS2-VASc score of 1 by virtue of their gender) are low risk and no antithrombotic therapy should be considered
ACC, American College of Cardiology; AHA, American Heart Association; ESC, European Society of Cardiology; HRS, Heart Rhythm Society
References
- Camm AJ, Kirchhof P, Lip GYH et al. Guidelines for the management of atrial fibrillation: the task force for the management of atrial fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369–2429. Camm AJ, Kirchhof P, Lip GYH et al. Guidelines for the management of atrial fibrillation: the task force for the management of atrial fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369–2429. Return to content
- Turakhia MP, Shafrin J, Bognar K et al. Estimated prevalence of undiagnosed atrial fibrillation in the United States. PLoS One 2018;13:e0195088. Turakhia MP, Shafrin J, Bognar K et al. Estimated prevalence of undiagnosed atrial fibrillation in the United States. PLoS One 2018;13:e0195088. Return to content
- Kirchhof P, Benussi S, Kotecha D et al. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Eur Heart J 2016;37:2893–2962. Return to content
- Morillo CA, Banerjee A, Perel P et al. Atrial fibrillation: the current epidemic. J Geriatr Cardiol 2017;14:195–203. Morillo CA, Banerjee A, Perel P et al. Atrial fibrillation: the current epidemic. J Geriatr Cardiol 2017;14:195–203. Return to content
- Boriani G, Pettorelli D. Atrial fibrillation burden and atrial fibrillation type: clinical significance and impact on the risk of stroke and decision making for long-term anticoagulation. Vascul Pharmacol 2016;83:26–35. Return to content
- Heeringa J, van der Kuip DAM, Hofman A et al. Prevalence, incidence and lifetime risk of atrial fibrillation: the Rotterdam study. Eur Heart J 2006;27:949–953. Heeringa J, van der Kuip DAM, Hofman A et al. Prevalence, incidence and lifetime risk of atrial fibrillation: the Rotterdam study. Eur Heart J 2006;27:949–953. Return to content
- Mendoza V, Scharf ML. Evaluation and management of chronic pulmonary thromboembolic disease. Hosp Pract (Minneap) 2011;39:50–61. Return to content
- Cresti A, Garcia-Fernandez MA, Miracapillo G et al. Frequency and significance of right atrial appendage thrombi in patients with persistent atrial fibrillation or atrial flutter. J Am Soc Echocardiogr 2014;27:1200–1207. Return to content
- 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;64:e1–e76. Return to content
- Jørgensen HS, Nakayama H, Reith J et al. Acute stroke with atrial fibrillation. The Copenhagen Stroke Study. Stroke 1996;27:1765–1769. Return to content
- Thygesen SK, Frost L, Eagle KA, Johnsen SP. Atrial fibrillation in patients with ischemic stroke: A population-based study. Clin Epidemiol 2009;1:55–65. Return to content
- Spieler JF, Lanoe JL, Amarenco P. Socioeconomic aspects of postacute care for patients with brain infarction in France. Cerebrovasc Dis 2002;13:132–141. Return to content
- Gage BF, Waterman AD, Shannon W et al. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864–2870. Return to content
- Lip GYH, Nieuwlaat R, Pisters R et al. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor based approach: The Euro Heart Survey on Atrial Fibrillation. Chest 2010;137:263–272. Lip GYH, Nieuwlaat R, Pisters R et al. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor based approach: The Euro Heart Survey on Atrial Fibrillation. Chest 2010;137:263–272. Return to content
- Lip GYH, Halperin JL. Improving stroke risk stratification in atrial fibrillation. Am J Med 2010;123:484–488. Return to content
- Olesen JB, Torp-Pedersen C, Hansen ML, Lip GYH. The value of the CHA2DS2-VASc score for refining stroke risk stratification in patients with atrial fibrillation with a CHADS2 score 0-1: A nationwide cohort study. Thromb Haemost 2012;107:1172–1179. Return to content
- You JJ, Singer DE, Howard PA et al. Antithrombotic therapy for atrial fibrillation: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012;141:e531S–e575S. You JJ, Singer DE, Howard PA et al. Antithrombotic therapy for atrial fibrillation: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012;141:e531S–e575S. Return to content
See Also
Peripheral Artery Disease: causes and consequences
See Also
Coronary Artery Disease: causes and consequences
