Reducing Stroke Risk in Atrial Fibrillation: Time to Update Scoring Again?
ACCEL | Obviously, OAC therapy is one means of reducing the risk of stroke in patients with AF, but there are a number of clinical factors associated with stroke or systemic embolism. In patients with nonvalvular AF, the 2014 guidelines recommend the CHA2DS2-VASc score for assessment of stroke risk (Class I, Level of Evidence: B). While earlier guidelines used the simpler CHADS2 risk calculator (Chronic heart failure; Hypertension; Age ≥ 75 years; Diabetes mellitus; or prior Stroke, transient ischemic attack [TIA] or thromboembolism [doubled]), data suggest that the more detailed risk calculator provides more information. CHA2DS2-VASc indicates: Chronic heart failure; Hypertension; Age ≥ 75 years (doubled); Diabetes mellitus; prior Stroke, TIA, or thromboembolism (doubled); Vascular disease; Age 65 to 74 years; and Sex category.
The guidelines also indicate a preference for HAS-BLED, a score to assess bleeding risk that is based on the presence of hypertension (systolic blood pressure > 160 mm Hg), abnormal liver or renal function, history of stroke or bleeding, labile international normalized ratios (INRs), elderly age (> 65 years), use of drugs that promote bleeding, or alcohol excess. A score ≥ 3 indicates a potentially “high risk” for bleeding, which may require closer observation of a patient for adverse risks, closer monitoring of INRs, or differential dose selections of oral anticoagulants or aspirin.
The guidelines do acknowledge that while HAS-BLED is better at discriminating risk than other scoring systems (HEMORR2HAGES and ATRIA), all three approaches have C indexes < 0.70 in the receiver operating curves, indicating only modest performance and poor predictive accuracy.
These scoring calculators are now available as computer tablet and smart phone apps, making it easier to follow the guidelines. In late 2014, the ACC launched a new Guideline Clinical App to serve as the mobile home for all the ACC/AHA guideline content and related tools. By the end of 2014, the application was scheduled to include content and tools from the guidelines on:
- Management of Heart Failure
- Assessment of Cardiovascular Risk
- Treatment of Blood Cholesterol
- Valvular Heart Disease
- Atrial Fibrillation
The app can be downloaded from the ACC (www.cardiosource.org/Science-And-Quality/Practice-Guidelines-and-Quality-Standards/Guidelines-App.aspx) – or available for free on iTunes and GooglePlay. Additional guidelines and features will be added over time.
According to ACC Heart Information and Technology Committee Member John J. Ryan, MD, the app is more than a reposting of the full guideline text. The app includes a collection of interactive tools such as dosing calculators, scoring tools, and algorithms that will be useful to clinicians implementing the guidelines. For each guideline, the app also includes an executive summary and key takeaway points.
SCORE! TAKE 3
The Table below shows the potency of individual risk factors, including one powerful predictor of stroke not presently accounted for in current risk calculators: renal disease.2
According to Jonathan P. Piccini, MD, an associate professor of medicine at the Duke Clinical Research Institute, when assessing risk stratification for stroke, don’t forget chronic kidney disease (CKD). In patients with known AF, the prevalence of CKD is 28% who have an estimated glomerular filtration rate (eGFR) < 60 and 10% who have an eGFR < 45.3,4
Dr. Piccini said the risk of stroke in patients with CKD and AF is so strong that renal function should be included in risk assessment. Call it the R2CHADS2 score:
- R2enal impairment (creatinine clearance < 60 ml/min) (2 points)
- Chronic heart failure (or EF < 35%)
- Age >75
- S2troke or TIA (2 points)
- January CT, Wann L, Alpert JS, et al. J Am Coll Cardiol. 2014;64:e1-e76. http://content.onlinejacc.org/article.aspx?articleid=1854231
- Piccini JP, Stevens SR, Chang Y, et al. Circulation. 2013;127:224-32.
- Alonso A, Lopez FL, Matsushita K, et al. Circulation. 2011;123:2946-53.
- Go AS, Fang MC, Udaltsova N, et al. Circulation. 2009;119:1363-9.
The 2014 guidelines for managing patients with AF indicate a preference for the CHA2DS2-VASc score for assessment of stroke risk and the HAS-BLED calculator for assessing bleeding risk.
One potent predictor of stroke not presently accounted for in current risk calculators: renal impairment (creatinine clearance < 60 ml/min).
Keywords: ACC Publications, CardioSource WorldNews
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