NHS Greater Glasgow & Clyde Area Drug and Therapeutics Committee
Greater Glasgow and Clyde Medicines
Medicines Update

Atrial fibrillation – Who should be anticoagulated?

Patients with recurrent paroxysmal, persistent or permanent atrial fibrillation (AF) have a high risk of thromboembolism, particularly stroke. Compared to patients without AF, the absolute risk of stroke is increased almost five fold. One year mortality after ischaemic stroke for patients in AF is 49.5%, compared with 27.1% for patients in sinus rhythm. Risk of stroke in patients with AF is about 4% per annum; this may be reduced by around 70% through appropriate prescribing of an oral anticoagulant (OAC). Risk of stroke and systemic embolism should be calculated using the CHA2DS2-VASc scoring tool. It is essential to ensure that patients with AF are anticoagulated where appropriate.

Key messages

  • At the point of AF diagnosis, calculate CHA2DS2-VASc and prescribe anticoagulation where appropriate. Do not await ECHO to prescribe an OAC
  • Review CHA2DS2-VASc risk score when reviewing patients with AF. This will help to identify patients who should be receiving anticoagulation but aren’t and also patients who may be anticoagulated inappropriately
  • Reassess CHA2DS2-VASc if patients develop further risk factors for stroke, or have a change in health status
  • Patients with AF and low risk of stroke (CHA2DS2-VASc = 0) prescribed an OAC should be reviewed to check if there is another indication for anticoagulation. If not, the OAC should be discontinued
  • Refer to the updated NHSGGC AF guideline for further details


The 2015 National Scottish Stroke Care Audit Report states that in 2014, approximately 25% of patients admitted to hospital with an ischaemic stroke were in AF. Only 24% of these patients were receiving an OAC. Although many cases of AF may have been new; in many others this could be either a failure to identify patients with AF, or a failure to start patients on an OAC.


GRASP-AF®


In 2014, The NHSGGC Heart MCN invested in a two year licensing of the GRASP-AF® audit tool with the aim of improving anticoagulation in patients with AF.
Four audits across 72% of general practices (n=198) between 2014 and 2016 captured data from 19,263 patients. The results showed an improvement in anticoagulation rates in high risk patients from 57% (2014) to 71% (2016). This is a direct result of case review by primary care clinicians, with subsequent patient invite to attend for review of treatment. It is conservatively estimated that this would prevent approximately 30 strokes.
The audit also showed that 22.5% (n=212) of patients with AF with low risk of stroke were prescribed an OAC. Inappropriate anticoagulation in this group of patients can result in higher risk of bleeding without any additional benefit in stroke risk reduction. These patients should be identified to determine if there is another clinical reason for anticoagulation, for example DVT/PE. This may require review of general practice registers to ensure that coding is accurate.

 

Published 09/10/17