Atrial Fibrillation (AF) is associated with a five-fold increase in the risk of ischaemic strokes. When compared to strokes from other causes, AF-related stokes are often far more debilitating, disabling and sometimes fatal.
Two-thirds of strokes can be avoided through timely and appropriate initiation of an oral anticoagulant (OAC). Risk stratification and clinical decision-making tools have been developed and validated in order to help:
- Determine an individual’s thromboembolic risk and whether an OAC is clinically indicated.
- Determine how best to mitigate against bleeding complications.
Table 1: Assessment of Thromboembolic Risk
|Congestive heart failure or left ventricular ejection fraction < 35%
|History of hypertension
|Age ≥ 75
|Stroke/transient ischaemic attack/systemic embolism
|Vascular disease history
|Age 65-74 years
|INTERPRETATION AND APPLICATION OF THE CHA2DS2-VASC SCORE
- Score < 0 men or <1 women = OAC is not recommended.
- Score = 1 men or 2 women = OAC should be considered.
- Score ≥ 2 = OAC should be offered.
ASSESSMENT OF BLEEDING RISK
The decision for thromboprophylaxis needs to balance the risk of bleeding events, especially intracranial haemorrhage (ICH), which is one of the most feared complication of OAC therapy, particularly with VKAs and confers a high risk of disability and/or death.
The HAS-BLED tool is the recommended risk assessment criteria that should be used in all patients with AF, and helps to identify those risk factors that can be actively modified to help reduce an individual’s bleeding risk.
Table 2: Assessment of Bleeding Risk
|Abnormal renal or liver function (1 point each)
|1 or 2
|Eldery (older than 65 years)
|Drugs or alcohol
|1 or 2
|INTERPRETATION AND APPLICATION OF THE HAS-BLED SCORE
A HAS-BLED score > 3 should not be used as a reason to omit OAC.
Unlike stroke risk factors, many of those characteristics that are used to determine bleeding risk are modifiable and should be proactively addressed to reduce the likelihood of a bleeding event.
The bleeding risk assessment is a dynamic process that will change over time and, as such, patients prescribed OAC should undergo regular review and follow up.
Key Points and Tips
- Don’t wait to anticoagulate!
- Shared decision-making and a patient-centred consultation are advocated when discussing the initiation of OAC.
- Regular review and follow up are advised to ensure the right choice and dose of OAC are prescribed.
Principal Pharmacist, Cardiac Services The Royal Wolverhampton NHS Trust/Clinical Advisor WMAHSN AF Programme
Estimates risk of major bleeding for patients on anticoagulation to assess risk-benefit in atrial fibrillation care. read more
Calculates stroke risk for patients with atrial fibrillation. read more