A new class of blood thinners and devices lower the high risk of stroke in people with atrial fibrillation (AFib). Duke doctors were involved in several of the studies that led to FDA approval for two of the newer drugs, and were among the first in the region to offer the new devices to people with atrial fibrillation.
Only 50% of AFib Patients on Medication to Prevent Stroke
Nearly three million people in the U.S. have atrial fibrillation, and their risk for stroke is five times higher than people without the heart rhythm disorder. That’s because the rapid, irregular heartbeats that define atrial fibrillation can cause blood clots to form, which lead to stroke.
Warfarin (Coumadin), is often prescribed to lower stroke risk in these people because it reduces the blood's tendency to form clots. This is commonly referred to as “thinning” the blood, explained James Daubert, MD, a heart rhythm specialist at Duke. However, frequent blood tests are needed to determine if the drug is making the blood too thin -- which can lead to serious bleeding risks including bleeding in the brain -- or too thick, which can cause stroke. Diet is a concern too, as vitamin K, found in green leafy vegetables, inhibits the drug’s effectiveness. These issues make some doctors hesitant to prescribe warfarin, and make some people unwilling to take it.
“Only about half of patients with atrial fibrillation who should be on an anticoagulant are on such medications to prevent stroke,” said Dr. Daubert.
Safer, More Effective Anticoagulants
In recent years, the FDA approved several new stroke-prevention medications in a class of drugs called novel oral anticoagulants (NOACs). They’ve proven to be a safer alternative, while performing as well or better in reducing stroke risk in people with atrial fibrillation. They consistently thin the blood, and there are no dietary restrictions. Reversal agents are now widely available in cases of emergency, alleviating much of the concern of doctors and patients about this new class of drugs.
At Duke, where doctors were the principal investigators of the clinical studies for two of the four new anticoagulants, rivaroxaban (Xarelto) and apixaban (Eliquis), NOAC medications are generally preferred over warfarin. Dr. Daubert explained, “We’re more aggressive about recommending these anticoagulants and more knowledgeable about the real risks and benefits. We have a lot of experience understanding the issues and managing the patients.”
New Devices Prevent Blood Clots from Forming
A new class of devices -- called left atrial appendage occlusion devices -- can protect against stroke in patients who are unable to safely take anticoagulants long-term. The atrium is one of the areas of the heart where blood collects. “The left atrial appendage is like a little cul de sac off the left atrium,” Dr. Daubert explained. “When you are in atrial fibrillation, and the atrium isn’t vigorously contracting, blood can stagnate and form a clot which can cause a stroke." These devices block the left atrial appendage and prevent clots from escaping.
One device, called the Watchman, uses a parachute-type mechanism to block the opening of the left atrial appendage. It was approved by the FDA in 2015. Duke was the first North Carolina hospital to implant the device and is now standardly offering it as a treatment option in patients needing an alternative to long-term anticoagulation to prevent strokes from atrial fibrillation.
“These procedures could help address the risk of stroke in the substantial portion of patients with atrial fibrillation who are either not taking, or are not good candidates for, or are at high risk with continual anticoagulation therapy,” Dr. Daubert said.