Healthbytes - Newer blood thinners for atrial fibrillation - yay or nay?


By now, you’ve probably seen the TV and print ads promoting newer blood-thinning agents for the treatment for nonvalvular atrial fibrillation. Blood thinning has long been the cornerstone of therapy for atrial fibrillation, a heart rhythm disorder which predisposes one to have strokes. For a long time, Coumadin (also called Warfarin) has been the only agent available to adequately thin the blood to prevent strokes in atrial fibrillation. However, since 2010, three newer agents, Pradaxa (Dabigatran), Xarelto (Rivaroxaban) and Eliquis (Apixaban), have received FDA approval for use as an alternative to Coumadin in the treatment of atrial fibrillation.

While Coumadin is often adequate for stroke prevention in patients with atrial fibrillation, this medication has several drawbacks. Blood thinning with Coumadin is very unpredictable. It has to be monitored at least monthly, and often more frequently, with blood tests. This is often inconvenient for busy patients. In addition, dietary changes can affect the blood thinning ability of Coumadin, and patients are advised not to stray far from their usual dietary habits. Specifically, green leafy vegetables like spinach or turnip greens will cause Coumadin to be less effective at thinning the blood and could require a patient to increase the dosage to maintain its effectiveness. Because of the unpredictability of Coumadin, often times a patient’s blood will be too thin, predisposing him to an increased risk of bleeding, or too thick, predisposing to strokes.

These newer anticoagulants were designed specifically to make blood thinning more predictable. None of the newest three agents require monitoring of the blood to ensure its effectiveness. You just take the medication and rest assured that you are being protected against strokes. All three agents were found in clinical studies to be at least equally effective as Coumadin for stroke prevention and were found to have less bleeding. Diet also becomes less of an issue because these newer agents work differently than Coumadin and are not affected by what one eats.

So why not switch everyone to one of the newer agents? Certainly many patients are switching. However, if a patient has done well for years on Coumadin and does not mind the monthly blood draws, then there is probably no reason to change. Some practitioners will also point out that there is no way to reverse the newer agents if a patient starts to bleed. Vitamin K and a blood product called fresh frozen plasma can reverse Coumadin. But it often takes many hours, even days, to adequately reverse Coumadin, whereas the newer agents’ blood thinning capacity has mostly worn off after a day.

And what about price? Coumadin, which has been around for years, is relatively cheap, but as you can imagine, the newer drugs can be very expensive. Insurance coverage has improved for the newer agents and will continue to get better, but there are times where the price of the newer agents make them prohibitive. Most of the time, if a patient has commercial prescription coverage or Medicare/Medicaid with prescription coverage, the newer agents are reasonable.

In my practice, I encourage most of my new patients being diagnosed with nonvalvular atrial fibrillation to try one of the newer agents. Patients with atrial fibrillation who are doing well with Coumadin are usually left on Coumadin unless the blood draws are too much of an inconvenience. And patients who have trouble keeping their blood within the therapeutic range on Coumadin are encouraged to change to one of the newer agents. Overall, I think the newer agents are at least as effective as Coumadin at preventing stokes in atrial fibrillation and probably have a slightly lower bleeding risk.

— Dr. Nick Willis is an interventional cardiologist. He is a member of the JRMC medical staff and is accepting new patients at Cardiology Associates in Pine Bluff. If you have a question for Willis, you can email him at healthbytes@jrmc.org.