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Stroke likelihood in AF patients predicted

A new score (CHA2DS2-VASc) for predicting the likelihood of stroke in patients with atrial fibrillation (AF) is more sophisticated than the old CHADS2 score, according to a report<(1) by Dr Jonas Bjerring Olesen of the Copenhagen University Hospital, Denmark, and colleagues, published online recently at bmj.com.

Olesen et al analysed a nationwide registry of 73,538 AF patients, who were not receiving anticoagulation, admitted to hospital in Denmark between 1997 and 2006. This represents the “the largest real world cohort of non-anticoagulated patients with non-valvular atrial fibrillation ever investigated,” according to the authors.

The previous system awards one point to congestive heart failure, hypertension, age >75, and diabetes, and two points for previous stroke, amounting to an overall score. In the CHA2DS2-VASc system age is weighed in two categories (65-74, or ≥75), and risk factors include female gender and vascular disease history. Each component in CHA2DS2-VASc scores one point except for stroke and age >75, which each score two.

In an accompanying editorial,(2) Dr Margaret C Fang, University of California, San Francisco, says that CHA2DS2-VASc is also “better than CHADS2 at identifying people at very low risk” – those who likely do not need anticoagulation. Dr Fang highlights that a mere 8.7% of patients in the cohort studied were considered low risk by CHA2DS2-VASc compared with 22.3% under the CHADS2 criteria.

Patients with a “low-risk” score had a rate of thromboembolism (TE) of 1.67 per 100 person-years under CHADS2 and 0.78 with CHA2DS2-VASc after one year. Those with an “intermediate risk” score had a TE rate of 4.75 with CHADS2 and 2.01 under CHA2DS2-VASc. The authors say this finding is “clinically important, as many of the patients at low risk according to CHADS2 are not at “truly low risk” and treatment guidelines are not conclusive for those at intermediate risk” (table 1).

table1

Table from European guidelines on the management of AF3
(Key)
AF = atrial fibrillation; CHA2DS2-VASc = cardiac failure, hypertension, age ≥75 (doubled), diabetes, stroke (doubled)-vascular disease, age 65–74 and sex category (female); INR = international normalized ratio; OAC = oral anticoagulation, such as a vitamin K antagonist (VKA) adjusted to an intensity range of INR 2.0–3.0 (target 2.5).

References

1. Olesen JB, Lip GYH, Hansen ML, et al. Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: Nationwide cohort study. BMJ 2011; DOI:10.1136/bmj.d124. Available at: http://www.bmj.com/content/342/bmj.d124.full

2. Fang MC. Anticoagulation in people with atrial fibrillation. Risk prediction tools help, but treatment must be tailored individually. BMJ 2011; DOI:10.1136/bmj.d530. Available at: http://www.bmj.com/content/342/bmj.d530.extract

3. The Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Guidelines for the management of atrial fibrillation. Eur Heart J 2010;31:2369-429.

Published on: March 3, 2011

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ENDORSED BY

  • ArrhythmiaAlliance
  • Stars
  • Anticoagulation Europe
  • Atrial Fibrillation Association
 

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