Abstract
Background
The Warfarin vs. Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial found no difference between warfarin and aspirin in heart failure patients in sinus rhythm for the outcome of first to occur of 84 ischemic strokes (IS), 7 intracerebral hemorrhages or 531 deaths. Pre-specified secondary analysis showed a 48% HR reduction (p=0.005) in IS risk for warfarin vs. aspirin. We examined this IS benefit for warfarin in post-hoc analyses.
Methods
We used the Wilcoxon rank sum test, stratified by prior IS or TIA, to compare the distributions of mRS among warfarin and aspirin IS patients in WARCEF. Median (md) scores and interquartile ranges (IQR) are shown for warfarin and aspirin arms, respectively. We used Fisher’s exact test to compare the effect of warfarin vs. aspirin on fatal IS; a stratified exact test to compare proportions of severe (mRS 3-5) IS; and stratified Poisson regression to compare IS subtypes.
Results
Twenty-nine (2.5%) of 1142 patients on warfarin and 55 (4.7%) of 1163 on aspirin had IS. The warfarin IS rate (0.72 per 100 patient years [/100PY]) was lower than for aspirin (1.36/100PY). There were no differences between warfarin and aspirin IS patients in baseline mRS (md 1, IQR, 2, N=29 vs. md 1, IQR 2, N=55); fatal IS (3/29, 10.3% vs. 6/55, 10.9%, p=1.0), or post-IS (after 90+30 days) mRS (md 2, IQR 3, n=23 vs. md 2, IQR 3, n=48, p=0.437). There were also no differences between warfarin and aspirin in change from baseline to post-IS mRS (md 1, IQR 3, n=23 vs. md 1, IQR 3, n=48, p=0.884). Cardioembolic IS was significantly less frequent on warfarin than on aspirin (9 [0.22/100PY] vs. 22 [0.55/100PY], p=0.012). The warfarin arm showed trends to fewer severe (mRS 3-5) IS (3/23 [13.0%] vs. 16/48 [33.3%], p=0.086) and a lower rate of IS of potential cardioembolic etiology (15 [0.37/100PY] vs. 27 [0.67/100PY] p=0.063). There was no difference between warfarin and aspirin in rate of non-cardioembolic IS (5 [0.12/100PY] vs. 6 [0.15/100PY], p=0.768).
Conclusions
Warfarin appears superior to aspirin in reducing the frequency of cardioembolic IS in heart failure patients in sinus rhythm. This is supported by trends to lower frequencies of severe IS and potentially cardioembolic IS in patients on warfarin compared to aspirin.