The Pharmaceutical Journal
Vol 279 No 7464 p144
11 August 2007

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AF patients at lower risk of stroke on warfarin than on aspirin

Patients with atrial fibrillation (AF) and no history of stroke who are on anticoagulant therapy are less likely to have a stroke than those taking an antiplatelet drug, according to a new Cochrane review (Cochrane Database of Systematic Reviews 2007; issue 3).

Researchers reviewed eight randomised trials, comprising a total of 9,598 patients, with an average follow-up of 1.9 years. The studies looked at patients with AF who had never had a stroke or transient ischaemic attack (TIA), given either dose-adjusted warfarin (or another anticoagulant) or antiplatelet therapy (with aspirin in most cases).

Compared with antiplatelet therapy, anticoagulation reduced the risk of all strokes (odds ratio 0.68, 95 per cent confidence interval 0.54–0.85; P=0.0007), fatal and non-fatal ischaemic strokes (0.53, 0.41–0.68; P<=0.00001 and systemic emboli (0.48, 0.25–0.90; P=0.02).

However, vascular death and all-cause mortality were similar between treatments (0.93, 0.75–1.15; P=0.50 and 0.99, 0.83–1.18; P=0.91, respectively), and the risk of intracranial haemorrhage was found to be higher for patients taking warfarin (1.98, 1.20–3.28; P=0.008).

“Most guidelines recommend adjusted-dose warfarin for AF patients at high risk for stroke and aspirin for those deemed at low risk or for those who cannot safely receive adjusted-dose warfarin,” the authors say.

“The threshold of benefit that would warrant anticoagulation remains controversial and depends on patient preferences and availability of optimal anticoagulation monitoring. In most cohorts of AF patients without prior stroke or TIA, about 40 per cent have a sufficiently low stroke rate during antiplatelet therapy that the absolute benefits of oral anticoagulants would be small.”