Chronic kidney disease (CKD) predisposes to high risks for both thrombo-embolism and bleeding. As a result, understanding the risk-benefit profile for use of anticoagulation therapies among CKD patients with atrial fibrillation is important to optimize patient outcomes. However, clinical trials evaluating efficacy and safety of anti-coagulants for atrial fibrillation generally exclude CKD patients and observational studies have had conflicting results. Accordingly, this prospective cohort study of 24,317 atrial fibrillation patients admitted with myocardial infarction in Sweden examined the association between warfarin therapy and patient outcomes by stage of CKD. Warfarin was prescribed in 21.8% patients and CKD (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73m²) was present in 51.7%. Compared with patients not treated with warfarin, the risk-adjusted composite outcome of death, myocardial infarction, or ischemic stroke was lower at 1 year of follow-up among patients treated with warfarin, regardless of CKD class. This reduction in thromboembolic events was not offset by an increased risk of bleeding events.

Conclusions

This study confirms the benefit of warfarin for thromboembolic risk protection in patients with CKD and atrial fibrillation. However, given that warfarin is known to increase bleeding risk, the lack of apparent bleeding risk with warfarin therapy in this study raises concerns that baseline bleeding risk was markedly lower among patients treated with warfarin. Given the increasing prevalence of both CKD and atrial fibrillation, a better understanding of the risk-benefit profile of anticoagulation in these high risk patients is needed.

• Carrero JJ, Evans M, Szummer K, et al. Warfarin, kidney dysfunction, and outcomes following acute myocardial infarction in patients with atrial fibrillation. JAMA. Mar 5 2014;311(9):919-928.

Summarized by Steven M. Bradley and Supriya Shore