Friday, April 15, 2016
The Watchman Left Atrial Appendage Occlusion Device:The alternative to blood thinners
By: Anil Rajendra, MD, FACC Cardiac Electrophysiologist Alabama Cardiovascular Group Grandview Medical Center
Atrial fibrillation (afib) is the most common arrhythmia and affects over 3 million Americans. It is an irregular, unorganized heart rhythm originating in the top chambers of the heart (atria). When people are in afib, there are electrical signals originating from numerous locations in the atria, causing the atria to fibrillate or “quiver” rather than contracting normally.
While afib is not a fatal arrhythmia, it does carry an increased risk of other issues, of which the most concerning may be strokes. Because the atria “quiver” rather than contracting normally, blood may pool in certain areas of the atria and form a clot. This clot can then dislodge or break and cause a stroke. Patients with afib have a 5 times increased risk of stroke. To minimize this risk, patients have traditionally been placed on anticoagulation (blood thinners) to prevent these blood clots from forming in the heart.
The overwhelming majority of these blood clots form in the left atrial appendage. The appendage is an outpouching in the left atrium and is a vestigial structure; i.e., it does not have a real purpose in normal heart function.
What is your risk of stroke?
As mentioned, the risk of stroke in patients with afib can be at least 5 times higher than patients without afib. The risk of stroke varies depending on other medical problems and risk factors. There are a few risk scores that are used to determine a patient’s risk of stroke. The most commonly used risk score is called the CHA2DS2-VASc score. 1 to 2 points are assigned to the following risk factors: congestive heart failure, hypertension, age > 75 (2 points), diabetes mellitus, previous stroke (2 points), vascular disease, age 65-74, female sex. According to current recommendations, patients with 2 or more points should be on anticoagulation (blood thinners) to lower the risk of stroke. The higher your risk score, the higher your risk of stroke.
How do we prevent strokes in these high risk patients?
The first line and most common modality to reduce the risk of stroke is the use of anticoagulation (blood thinners). Warfarin (Coumadin) is the oldest of the blood thinners, having been used for many years. Because warfarin has been around for a long time, it is relatively inexpensive. However, it does require frequent blood monitoring as well as diet restrictions.
More recently, newer anticoagulants have become commercially available, namely dabigatran (Pradaxa), rivoraxaban (Xarelto), apixaban (Eliquis), and edoxaban (Savaysa). These newer drugs performed well in clinical trials comparing their efficacy against warfarin, and all gained FDA approval for stroke prevention in patients with afib.
However, many patients cannot take blood thinners due to high risk for bleeding or previous bleeding. In addition, some patients just do not want to take blood thinners long term. Until recently, there was not an option for stroke prevention in these patients. Now there is a device, called the Watchman left atrial appendage closure (LAAC) device that is an alternative to oral anticoagulation for stroke prevention.
The Watchman device
The Watchman LAAC device gained FDA approval in the spring of 2015 after being studied extensively in 2 separate clinical trials and 2 subsequent registries. As mentioned previously, the left atrial appendage is the location where the majority of clots form in the heart. This device is implanted in the opening of the left atrial appendage, with the heart muscle growing over the device and permanently sealing off the appendage. The Watchman device was studied against warfarin in 2 large studies and proved to be as good as warfarin at preventing strokes.
The Watchman is shaped like a parachute and has a nitinol frame with a mesh covering over it. Using a minimally invasive technique through access in the femoral vein in the groin area, the device is implanted in the left atrial appendage. Ultrasound and fluoroscopy (x-ray) are used to position the device in the proper location. After the procedure, patients remain in the hospital overnight and are discharged home the following day. Patients remain on blood thinners for 45 days after implant. At 45 days, they have another brief ultrasound to ensure the device is still in good location and a good seal has formed. If that ultrasound shows a good seal, then patients can discontinue blood thinners at that time.
My partners and I with Alabama Cardiovascular Group at Grandview Medical Center were the first to implant the device in the state of Alabama. We have successfully implanted the device in over 40 patients and have had outstanding results. Our patients who have undergone the procedure have been able to discontinue their blood thinners and still be protected against stroke.
Atrial fibrillation is a very common, complex arrhythmia that increased the risk of stroke in patients afflicted with the disorder. Traditionally, anticoagulation has been the only modality available to reduce the risk of stroke in those patients. For patients that cannot take anticoagulation, however, the Watchman LAAC device is a very viable and effective treatment option to reduce the risk of stroke without the need for long-term anticoagulation. If you have afib and cannot take blood thinners, inquire if you are a candidate for the Watchman device.