WATCHMAN LAA Closure Technology
What is it?
The WATCHMAN LAA Closure Technology consists of a delivery catheter and a device that is permanently implanted in the left atrial appendage (LAA) of the heart. The device often referred to as the WATCHMAN, prevents LAA blood clots from entering the bloodstream and potentially causing a stroke. It is made of a self-expanding, nickel-titanium (Nitinol) frame with an attached woven PTFE fabric cap.
How does the physician implant the device?
The physician inserts the delivery catheter into the body through a vein in the leg. The catheter is advanced through the bloodstream until it reaches the upper right chamber of the heart (right atrium). The physician makes a small hole through the wall between the two upper chambers of the heart (atrial septum) so that the catheter reaches the LAA. The physician then pushes the WATCHMAN through the delivery catheter into the LAA where it opens up like an umbrella and is permanently implanted. Once the WATCHMAN is in place, a thin layer of tissue grows over it in about 45 days. This keeps blood clots in the LAA from entering the bloodstream.
When is it used?
The WATCHMAN is FDA approved for use in patients who have atrial fibrillation (AFib) not related to heart valve disease. In AFib, the two upper chambers (atria) of the heart no longer contract together in a coordinated manner and the heart beat (pulse) becomes irregular. Because the atria no longer contract normally in AFib, the blood flow in the heart can be slower than normal. This change in blood flow may cause blood clots to form. During AFib, most blood clots that originate in the heart develop in the LAA. These blood clots can break loose, travel through the bloodstream, and block a blood vessel in the brain. If this occurs, the part of the brain that is supplied by that blood vessel can become permanently damaged within minutes (also known as a stroke).
The WATCHMAN should only be used in patients who:
- have atrial fibrillation not related to heart valve disease.
- are at increased risk for a stroke.
- are recommended for blood thinning medicines.
- are suitable for warfarin (a blood thinner also known as Coumadin).
- have an appropriate reason to seek a non-drug alternative to warfarin.
What will it accomplish?
The WATCHMAN was evaluated in four clinical studies, in which two studies compared the WATCHMAN to warfarin. Many patients with AFib take warfarin or other FDA-approved blood-thinning medicines to prevent a stroke caused by a blood clot in the brain. However, warfarin can increase the risk of bleeding anywhere in the body. If bleeding happens in the brain, this can also cause a stroke.
These two clinical studies suggested that warfarin was better than the WATCHMAN in preventing strokes caused by a blocked blood vessel in the brain. However, the number of strokes caused by bleeding in the brain was lower in the WATCHMAN patients compared to the warfarin patients.
The overall rate of serious bleeding was similar in the WATCHMAN and warfarin patients. Within several months after the device was implanted, the rate of serious bleeding was higher in the WATCHMAN patients as compared to warfarin patients. However, beginning six months after the device implant procedure, the rate of serious bleeding was lower in WATCHMAN patients.
In one of the clinical studies that evaluated the WATCHMAN, 226 out of 246 WATCHMAN patients (approximately 92%) were able to stop taking their warfarin 45 days after the device was implanted. Within a year after the implant procedure, 231 out of 234 patients remaining in the study (over 99%) were able to stop taking warfarin.
To prevent strokes, most AFib patients can safely take blood thinning medicines(like warfarin) without serious side effects. However, in some patients, blood thinning medicines can be difficult to use due to bleeding concerns. In choosing a treatment, physicians should consider the risks and benefits of blood thinning medicines compared to the WATCHMAN for each individual patient. This includes the risk that either kind of stroke (caused by a blocked blood vessel or by bleeding) might occur.
When should it not be used?
The WATCHMAN should not be used in patients who:
- currently, have a blood clot in their heart.
- have had surgical repair of the wall between the upper chambers of the heart (atrial septum) or have a device placed in the atrial septum, or have an LAA that is too large or too small to fit the WATCHMAN.
- cannot tolerate blood thinning medicines (warfarin, clopidogrel, and aspirin).
- have a sensitivity to nickel or titanium (Nitinol) or any other material that is part of the device.