Warfarin more effective than aspirin in prevention of stroke in people with atrial fibrillation

Warfarin is more effective than aspirin in prevention of stroke in people with a certain type of irregular heartbeat who are aged 75 or over, conclude authors of an Article published in this week's edition of The Lancet.

Dr Jonathan Mant, University of Birmingham, UK and colleagues did a study (the Birmingham Atrial Fibrillation Treatment of the Aged Study/BAFTA) to determine how warfarin and aspirin affected stroke risk, and whether use of these drugs outweighed the increased risk of bleeding in elderly patients. They studied 973 patients aged 75 years or over (average 81 years), all of whom had atrial fibrillation, a particular type of irregular heartbeat (arrhythmia). Of these patients, 488 were randomised to receive warfarin and 485 to receive aspirin, and were followed up for an average of 2.7 years. The incidence of fatal or disabling stroke (either ischaemic or haemorrhagic), intracranial haemorrhage, and clinically significant arterial embolism were studied in each group.

The researchers found that in the warfarin group, 24 serious events occurred – 21 strokes, two intracranial haemorrhages, and one systemic embolus. In the aspirin group, there were 48 serious events – 44 strokes, one intracranial haemorrhage, and three systemic emboli. Thus patients taking warfarin were less than half as likely to suffer a serious event (52% lower risk) as those taking aspirin.

They say: “We showed that the frequency of stroke, arterial embolism, and intracranial haemorrhage was significantly lower in patients on warfarin than in those on aspirin”, adding that their results show that warfarin could safely be used much more widely by older people.

They conclude: “We recorded no evidence that anticoagulants [warfarin] were more hazardous than aspirin therapy in this age group, although the study had limited power to detect those differences.”

In an accompanying Comment, Dr David Garcia, University of New Mexico, Albuquerque, USA, says: “BAFTA firmly establishes the superior efficacy of warfarin as a stroke-prevention strategy in elderly patients with atrial fibrillation. However, in the future, our greatest challenge will be to identify those patients (elderly or not) who are truly at the highest risk of major bleeding, particularly intracranial haemorrhage. For everyone else, no matter the age group, the benefits of well-managed warfarin substantially outweigh its risks.”