Sunday, September 8, 2013

Thromboembolic Prophylaxis in Patients with AFib and CKD: Caught between the Devil and the Deep Blue Sea

I often get curb-sided by cardiologists and internists for my opinion on using warfarin or other anticoagulants for thromboembolic risk prophylaxis in CKD +/- Afib patients. A similar conundrum of using anticoagulation for stroke prophylaxis in dialysis patients was discussed about three years ago on this blog by Conall. Like many other issues in patients with CKD, things are not always black-and-white, and a lot could depend on patient and physician preference.  This often makes the “right answer” a confusing exercise, since CKD patients are also at a higher bleeding risk. Most randomized trials addressing this issue have excluded patients with a GFR below 30. Furthermore, newer direct thrombin inhibitors (dabigatran), or Factor Xa inhibitors (apixaban, rivaroxaban) are available, which might be better than warfarin, at least in the early-CKD patient (although the lack of a reversing antidote is a potential pitfall). Finally, warfarin has a well-established link with vascular calcification (a mortality risk) in dialysis patients. As nephrologists, it is imperative that we are knowledgeable about the best-available data that can help us make an evidence-based recommendation, and so I put together a concise decision-table with links to primary literature sources.
In addition to the “traditional” risk factors for stroke in patients with AFib (as exemplified by the acronym CHADS), it is known that CKD itself is an independent risk factor for stroke. Thus CKD patients, both with, and without AFib, are at an increased risk of stroke. This has been demonstrated in CKD as well as dialysis patients, and the risk worsens with decline in GFR. 
Thus, with the above background in mind, the two main variables that determine what, if any, anticoagulation is to be used in this setting, are (1) the stage of CKD, and (2) the CHADS2 score:

CHADS2 Score


Stage 3, eGFR 30-59

Stage 4, eGFR 15-29

Stage 5, eGFR less than 15, or dialysis



AC (Direct thrombin inhibitors (dabigatran), and Factor Xa inhibitors (rivaroxaban, apixaban) potentially superior to warfarin

AC (warfarin preferred since no data on direct thrombin or factor Xa inhibitors)

AC (warfarin preferred since no data on direct thrombin or factor Xa inhibitors)

ASA = Aspirin
AC = Anticoagulation
?? = Expert opinion only, no strong evidence available - weight risks vs. benefits
Remember that no antithrombotic therapy is warranted if bleeding is a concern

Posted by Veeraish Chuahan

(Apologies for any formatting issues)

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