Warfarin versus Aspirin for Prevention of Stroke in Heart Failure: A Meta-analysis of Randomized Controlled Clinical Trials

Abstract

There is clinical equipoise between warfarin and aspirin for stroke prevention in patients with heart failure in sinus rhythm (SR). The objective of this meta-analysis was to pool risk estimates for stroke, mortality, and intracerebral hemorrhage (ICH) from published clinical randomized controlled trials (RCTs). MEDLINE, EMBASE, the Cochrane Library, and clinicaltrials.gov were searched for English-language RCTs comparing warfarin to aspirin in heart failure through May 2012. Pooled relative risk (RR) was calculated from a random-effects model. Four RCTs (n=3681) met the criteria for study inclusion. Warfarin was associated with a lower risk of stroke compared with aspirin (pooled RR, .59; 95% confidence interval [CI], .41-.85; P=.004). The number needed to treat (NNT) was 61. There was no difference between warfarin and aspirin in mortality (pooled RR, 1; 95% CI, .88-1.13), and ICH (pooled RR, 2.17; 95% CI, .76-6.24). Among secondary outcomes, warfarin was associated with almost twice the risk of major hemorrhage (pooled RR, 1.95; 95% CI, 1.37-2.76; P=.0001) compared with aspirin. The number needed to harm (NNH) was 34. There was no significant difference between warfarin and aspirin in risk of myocardial infarction (MI) (pooled RR, 1.02; 95% CI, .65-1.6], and heart failure exacerbation (HFE) (pooled RR, 1.11; 95% CI, .76-1.63). Compared with aspirin, warfarin reduced the risk of stroke while conferring an increased risk of major hemorrhage. Warfarin does not increase mortality or confer an increased risk of ICH compared with aspirin.