Thromboembolism in AF (secondary prevention)

Patients with atrial fibrillation who have experienced a transient ischaemic episode (TIA) or stroke have an increased risk of further cerebrovascular events. Treatments aimed at preventing further strokes are termed secondary prevention therapies.

NICE (1)

• people with disabling ischaemic stroke who are in atrial fibrillation should be treated with aspirin 300 mg for the first 2 weeks before considering anticoagulation treatment

Evidence has shown that in cases of non-rheumatic atrial fibrillation, anticoagulation reduces of the risk of subsequent stroke. In absolute terms, 90 vascular events, mainly strokes, are prevented if 1000 patients are treated with anticoagulation for one year. The target INR is 2.0-3.0.

Anticoagulant therapy should not be started until brain imaging has excluded haemorrhage, and 14 days have passed from the onset of an ischaemic stroke (2).

Aspirin is safe but less effective and should only be used when anticoagulation is contraindicated. Aspirin prevents 40 vascular events each year for every 1000 patients treated.

Reference:

• (1) NICE (May 2019). The diagnosis and acute management of stroke and transient ischaemic attacks
• (2) The Royal College of Physicians. National Clinical Guidelines for Stroke. London, 2000.