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ORAL ANTICOAGULATION IS SUPERIOR TO COMBINED ANTI-PLATELET THERAPY IN PATIENTS WITH ATRIAL FIBRILLATION AND EVEN AN ADDITIONAL SINGLE RISK FACTOR FOR STROKE: AN ANALYSIS FROM THE ACTIVE-W TRIAL

JS Healey, RG Hart, M Pfeffer, SH Hohnloser, S Yusuf, SJ Connolly
Hamilton, Ontario

INTRODUCTION: The ACTIVE-W trial demonstrated that oral anticoagulation (OAC) is more effective than combined treatment with clopidogrel and aspirin (C+A), at preventing cardiovascular events in patients with atrial fibrillation (AF). However, as OAC is associated with bleeding complications, several stratification schemes have been devised to identify patients whose risk of stroke is low, in whom the benefits of OAC do not exceed its risks.
METHODS: Patients in ACTIVE-W were classified using the CHADS-2 stratification scheme (1 point for history of congestive heart failure, hypertension, age > 75 years, diabetes mellitus and 2 points for history of stroke or TIA). Rates of stroke and major bleeding were calculated for each level of CHADS-2 score.
RESULTS: The stroke rates for patients with a CHADS-2 score of £ 1 were: 1.43 % per year for patients receiving clopidogrel and aspirin and 0.43 % per year for patients receiving OAC (RR = 3.40, 95 % CI: 1.46 - 7.90, p = 0.004). Similarly, among patients with a CHADS-2 score of > 2, the stroke rates were 3.12 % per year and 1.97 % per year (RR = 1.59, 95 % CI: 1.12 - 2.26, p = 0.01). The benefits of OAC were not statistically different between the two groups, based on CHADS-2 score (p for interaction = 0.11) and both groups derived an annual reduction in stroke of 1 % with OAC.
Among patients with a CHADS-2 score of £ 1, the rate of severe bleeding was 1.37 % per year among patients assigned to clopidogrel plus aspirin, and 0.81 % per year among patients randomized to OAC (RR = 1.75, 95% CI: 0.88 - 3.45, p = 0.11). For patients with a CHADS-2 score of > 1, severe bleeding occurred at a rate of 1.96 % per year in the clopidogrel plus aspirin arm and 2.05 % per year in the OAC arm (RR = 0.96, 95 % CI: 0.65 - 1.42, p = 0.84).
CONCLUSIONS: In the treatment of AF patients, with even a single high-risk factor for stroke, treatment with OAC is superior to the combination of aspirin and clopidogrel, when one considers both stroke and bleeding complications.
DNC

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