The risks and benefits of anticoagulation for
patients with both heart failure and atrial fibrillation are unclear. We
hypothesized that anticoagulation was associated with improved clinical
outcomes of heart failure patients with atrial fibrillation independent of
other risk factors. We conducted a retrospective cohort study of clinical registry data
linked to Medicare claims for new users of oral anticoagulation (warfarin) without
contraindications, discharged home alive, and stratified by CHADS2 score. Outcomes of interest were propensity score-adjusted estimates of the
effects of warfarin at discharge on all-cause mortality, thromboembolic events,
major adverse cardiovascular events, and bleeding events. Among 10,494 patients with heart
failure and atrial fibrillation, the 2249 patients newly treated with warfarin
had lower 1-year mortality (27.7% vs 39.3% for CHADS2 score ≤ 3
[P < .001]; 31.6% vs
41.8% for CHADS2 score > 3 [P < .001]) than patients not treated with warfarin.
There was no significant difference in thromboembolic events, major adverse
cardiovascular events, or bleeding events at 1 year. After multivariate
adjustment, exposed individuals in both CHADS2 subgroups had lower
adjusted 1-year mortality (CHADS2 ≤ 3: hazard ratio, 0.78 [95%
confidence interval, 0.69-0.89]; CHADS2 > 3: 0.78
[0.66-0.93]). In conclusion, warfarin use in heart failure patients with atrial
fibrillation was associated with improved survival at 1 year independent of
baseline CHADS2 score. However, there was no significant reduction
in clinical events, such as thromboembolic or major adverse cardiovascular
events at 1 year that might simply explain the survival benefit associated with
warfarin.
Credits: Zubin J. Eapen, MD; Xiaojuan Mi, PhD; Gregg C. Fonarow, MD; Soko Setoguchi, MD, DrPH; Jonathan P. Piccini, MD, MHS; Roger M. Mills, MD; Winslow Klaskala, PhD, MS; Lesley H. Curtis, PhD; Adrian F. Hernandez, MD, MHS.