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Stroke Risk Assessment

Stroke Risk Stratification

Atrial fibrillation (AF), the most frequently encountered cardiac arrhythmia, is a major risk factor for ischemic stroke.1,2 On average, patients with AF have a 5-fold higher risk for stroke than the general population.3 However, an individual patient’s risk of stroke varies depending on the presence or absence of various risk factors.

Stroke risk stratification scores rely on a combination of demographic and clinical characteristics. The most well-known and validated stroke risk stratification score is the CHADS2 score (Table 1).4 CHADS2 scores have been broadly categorized as low (0), intermediate (1), and high (2–6) risk of stroke.5 In older guidelines, anticoagulant therapy was recommended for high-risk patients, whereas an anticoagulant or aspirin was recommended for moderate-risk patients and aspirin alone for low-risk.1,4,6-8

Table 1: CHADS2 risk score for prediction of stroke risk in AF.

chart 1

Legend:CHF= congestive heart failure; TIA= transient ischemic attack

However, the traditional stroke risk stratification schemes, including the CHADS2 risk score, are limited by excluding other known stroke risk factors such as vascular disease (myocardial infarction and peripheral vascular disease) and female sex5, as well as consideration of the increased stroke risk that exists in patients younger than 75 years of age. Such exclusions lead to underestimation of stroke risk and result in under treatment with OAC for stroke prevention.

The more recently developed and validated CHA2DS2-VASc risk stratification score9-14(Table 2), is a modification and expansion of the CHADS2 scheme that incorporates additional stroke risk factors.5It offers the main advantage of better identifying “truly low-risk” individuals that likely do not benefit from anticoagulation. The annual rate of thromboembolic events associated with CHA2DS2-VASc=0 was 0%, compared with 1.40% with CHADS2 =0 in the same patients. In the updated guidelines, anticoagulation should be considered for AF patients with ≥1 stroke risk factors or a CHA2DS2-VASc ≥1(Table 3).15-16

Table 2: CHA2DS2-VASc risk score for prediction of stroke risk in AF.

chart 2

Legend:LV= left ventricular; TIA= transient ischemic attack

 

Table 3: Adjusted risk of stroke for CHADS2 and CHA2DS2-VASc scores

Score

CHADS2 (%/Year)5

CHA2DS2-VASc (%/Year)6

0

1.9

0

1

2.8

1.3

2

4

2.2

3

5.9

3,2

4

8.5

4.0

5

12.5

6.7

6

18.2

9.8

7

 

9.6

8

 

6.7

9

 

15.2

 

REFERENCES

 

1.         Fuster V, Ryden LE, Cannom DS, et al. 2011 ACCF/AHA/HRS focused updates incorporated into the ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines.Circulation.2011;123(10):e269-367.

2.         Go AS, Hylek EM, Phillips KA, et al. Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the AnTicoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study.JAMA.2001;285(18):2370-2375.

3.         Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation as an independent risk factor for stroke: the Framingham Study.Stroke.1991;22(8):983-988.

4.         Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation.JAMA.2001;285(22):2864-2870.

5.         Lip GY, Nieuwlaat R, Pisters R, Lane DA, Crijns HJ. 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(2):263-272.

6.         Gage BF, van Walraven C, Pearce L, et al. Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin.Circulation.2004;110(16):2287-2292.

7.         Singer DE, Albers GW, Dalen JE, et al. Antithrombotic therapy in atrial fibrillation: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).Chest.2008;133(6 Suppl):546S-592S.

8.         Fuster V, Ryden LE, Cannom DS, et al. 2011 ACCF/AHA/HRS focused updates incorporated into the ACC/AHA/ESC 2006 Guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines developed in partnership with the European Society of Cardiology and in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society.J Am Coll Cardiol.2011;57(11):e101-198.

9.         Boriani G, Botto GL, Padeletti L, et al. Improving stroke risk stratification using the CHADS2 and CHA2DS2-VASc risk scores in patients with paroxysmal atrial fibrillation by continuous arrhythmia burden monitoring.Stroke.2011;42(6):1768-1770.

10.       Van Staa TP, Setakis E, Di Tanna GL, Lane DA, Lip GY. A comparison of risk stratification schemes for stroke in 79,884 atrial fibrillation patients in general practice.J Thromb Haemost.2011;9(1):39-48.

11.       Lip GY, Frison L, Halperin JL, Lane DA. Identifying patients at high risk for stroke despite anticoagulation: a comparison of contemporary stroke risk stratification schemes in an anticoagulated atrial fibrillation cohort.Stroke.2010;41(12):2731-2738.

12.       Poli D, Lip GY, Antonucci E, Grifoni E, Lane D. Stroke risk stratification in a "real-world" elderly anticoagulated atrial fibrillation population.J Cardiovasc Electrophysiol.2011;22(1):25-30.

13.       Olesen JB, Lip GY, Hansen ML, et al. Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study.BMJ.2011;342:d124.

14.       Camm AJ, Kirchhof P, Lip GY, 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(19):2369-2429.

15.       Camm AJ, Lip GY, De Caterina R, et al. 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association.Eur Heart J.2012;33(21):2719-2747.

16.       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.Circulation.2014;130(23):e199-267.

 

In this video, Dr. Samuel Goldhaber explains stroke risk stratification:

 

 

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