Does warfarin for stroke thromboprophylaxis protect against MI in atrial
fibrillation patients?
Author(s): Lip GY, Lane DA.
Affiliation(s): University of Birmingham Centre for Cardiovascular Sciences, Birmingham, UK.
Publication date & source: 2010, Am J Med. , 123(9):785-9
The Randomized Evaluation of Long-term anticoagulation therapY (RE-LY) study
demonstrated a significant increase in myocardial infarction events with
dabigatran compared with warfarin, provoking renewed interest in whether vitamin
K antagonists are useful drugs for the prevention of myocardial infarction in
high-risk patients with atrial fibrillation. Present analyses examined whether
there was an increased risk of myocardial infarction associated with non-warfarin
anticoagulants (Stroke Prevention with the ORal direct Thrombin Inhibitor
ximelagatran compared with warfarin in patients with non-valvular atrial
Fibrillation III and IV, RE-LY, Amadeus) or "anticoagulant equivalents" (Atrial
fibrillation Clopidogrel Trial with Irbesartan for the prevention of Vascular
Events) in patients with atrial fibrillation who are prescribed anticoagulation
for stroke thromboprophylaxis. The overall annual event rate for those receiving
warfarin was 0.98% compared with 1.32% for those receiving comparators. Warfarin
was associated with a significant reduction in myocardial infarction (relative
risk 0.77; 95% confidence interval (CI), 0.63-0.95), an effect largely driven by
the RE-LY trial. Sensitivity analyses, excluding RE-LY, revealed a nonsignificant
reduction in myocardial infarctions (relative risk 0.83; 95% CI, 0.62-1.10); an
analogous analysis excluding the Atrial fibrillation Clopidogrel Trial with
Irbesartan for the prevention of Vascular Events demonstrated a significant
reduction in myocardial infarctions (relative risk 0.80; 95% CI, 0.64-1.00).
Warfarin might provide a protective effect against myocardial infarction compared
with non-warfarin anticoagulants or "anticoagulation equivalents" in patients
with atrial fibrillation who are prescribed anticoagulation for stroke
thromboprophylaxis.
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