A new device may help eliminate the need for blood thinner medications in patients with atrial fibrillation who are at high risk for stroke.
Atrial fibrillation is the most common electrical abnormality of the heart – and it becomes increasingly common the older we get. It is also one of the most common causes of stroke, one of the most dreaded conditions we face as we age.
The UVM Medical Center is participating in a multi-center trial evaluating a new cardiac device designed to prevent strokes caused by atrial fibrillation. It’s called the Watchman device, and I’d like to share with you how it works, but before that, let’s review the connection between atrial fibrillation and stroke.
The Left Atrial Appendage: What Connects Atrial Fibrillation to Stroke?
Atrial fibrillation causes the two upper chambers of the heart – called the atrial chambers – to quiver. Normally, the heart’s upper chambers engage in a normal smooth squeezing motion.
Everyone’s heart has atrial appendages. These are pouches (about the size of your thumb) attached to the right and left atrial chambers. A stroke can happen when blood pools in the atrial chambers during atrial fibrillation. Consequently, blood clots can form inside the appendage – if a clot forms, it increases your chances of having a stroke, or other related problems.
We cardiologists worry most about the left atrial appendage because it is part of the circulation route that leads to the brain: If a clot forms in the left atrial appendage, a clot can make its way through the main atrial chamber to the ventricle below, which can then launch the clot into an artery within the brain. These clots tend to be large, which is why strokes associated with atrial fibrillation are typically the worst kind of stroke.
The Traditional Way of Treating Blood Clots
We try to prevent blood clots from forming in the atrial appendages by treating patients with blood thinning medications, such as Coumadin (also known as Warfarin). These are medications that inhibit the body’s ability to form a blood clot. But, there are limitations: 1) These medications only prevent about 66 percent of strokes from occurring, and 2) They increase a patient’s risk for bleeding.
Coumadin, the most commonly used blood thinner, is affected by diet and other medications. It requires that a patient undergo frequent blood testing to monitor dosage and diet regulation as a variety of foods (particularly foods rich in Vitamin K, like kale, spinach – and everyone’s favorite – Brussels sprouts) may affect the medication’s effectiveness.
An Alternative Approach: The Watchman
An alternative approach is now available to patients in Vermont as part of a research trial: We can perform a procedure through which we close the appendage mechanically. The name of the device is the Watchman, an umbrella-like device that is delivered through a thin catheter that is snaked up to the patient’s heart through a vein in the groin.
Once the device is positioned in the left atrial appendage and tested to ensure it is well anchored and providing adequate coverage, the device is released from the catheter by unscrewing the metal strut (as you can see in the picture above). The catheter is then removed from the body. After about 4-6 weeks, the device becomes completely coated with tissue from the body’s natural healing processes. At this point, the patient can then stop taking his or her blood thinner.
This device is currently under study as part of an FDA mandate to confirm adequate safety and that the device works as well as it has been shown to in prior studies. The UVM Medical Center has already participated in the first part of the study, during which patients were randomly selected to either receive the device or stay on a blood thinner.
We are currently in a portion of the study called a “registry,” during which any patient who meets the study’s criteria may have the device implanted. (Any patient who has atrial fibrillation and is on Coumadin, or a similar blood thinner like Xarelto or Pradaxa, may be a candidate to participate in this study. You may ask your physician whether or not this might be a reasonable option for you).
Learn more about the Cardiac Catheterization at the UVM Medical Center.
Daniel Lustgarten, MD, is a cardiologist at the UVM Medical Center and director of the UVM Medical Center’s Cardiac Electrophysiology Clinical Trials Program. He is also an associate professor in the Larner College of Medicine at UVM.