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What the Watchman Device Is and How It Works

The Watchman device is a small implant designed to reduce stroke risk in people with a heart condition called atrial fibrillation (AFib). To understand why this device matters, it helps to know what happens in AFib.

Normally, your heart beats in a steady, organized rhythm. The upper chambers (atria) push blood down into the lower chambers (ventricles), which then pump blood throughout your body. In AFib, the atria beat very quickly and irregularly—sometimes hundreds of times per minute. This chaotic rhythm prevents the atria from fully emptying their blood.

When blood sits still in the heart, it can form clots. These clots can travel to the brain and cause a stroke. People with AFib have a much higher stroke risk than people with regular heart rhythms. In fact, AFib increases stroke risk about five times compared to people without the condition.

The Watchman device works by blocking a small pouch in the heart called the left atrial appendage (LAA). This pouch is where most blood clots form in people with AFib. The device is a small, umbrella-shaped screen that is placed directly into this pouch during a procedure. Once in place, the device prevents clots from leaving the LAA and traveling to the brain.

The procedure to place the Watchman device is called left atrial appendage occlusion (LAAO). A doctor inserts a tube called a catheter through a vein in your leg and guides it to your heart. The Watchman device comes folded inside this catheter. Once positioned in the LAA, the device is released and expands to fit the opening of the pouch. The entire procedure usually takes about one to two hours.

Practical Takeaway: Understanding how the Watchman device works—by blocking the area where blood clots form in an irregular heartbeat—helps explain why doctors may suggest this option for certain AFib patients.

Who Might Benefit From the Watchman Procedure

Not every person with AFib is a candidate for the Watchman device. Your doctor looks at several factors to determine whether this procedure might be an option for you. Understanding these factors can help you have a more informed conversation with your healthcare team.

The primary candidates for Watchman placement are people with non-valvular AFib who have a high risk of stroke. "Non-valvular" means the AFib is not caused by a problem with a heart valve. Your doctor calculates your stroke risk using a scoring system called CHA₂DS₂-VASc. This score considers factors like your age, whether you have high blood pressure, whether you have had a stroke before, and other health conditions. If your score indicates moderate to high stroke risk, your doctor might discuss stroke prevention options with you, including the Watchman device.

One important consideration is whether you can take blood thinners. Many people with AFib take medications like warfarin or apixaban to prevent clots. These are very effective at reducing stroke risk. However, some people cannot take these medications because they have had serious bleeding problems, or the medications do not work well for them. If blood thinners are not an option for you, the Watchman device may be something to explore.

Your heart structure also matters. Your doctor will perform an echocardiogram—an ultrasound of your heart—to measure the size and shape of your LAA. The LAA opening must be a certain size for the device to fit properly. If your LAA is too small or too large, the device may not work well. Additionally, if there is already a blood clot in your LAA, you would need treatment to clear it before the procedure.

Other medical conditions factor into the decision as well. You need to be healthy enough to tolerate a catheter procedure. If you have severe kidney disease, certain lung conditions, or other serious health problems, the procedure may carry higher risks. Your doctor will review your complete medical history to understand whether the benefits of the procedure outweigh the risks in your specific situation.

Age alone is not a barrier. People in their 60s, 70s, 80s, and even 90s have received Watchman devices. What matters more is your overall health and your risk of stroke versus your risk of complications from the procedure.

Practical Takeaway: Learning about the factors doctors consider—such as stroke risk score, ability to take blood thinners, and heart structure—helps you understand why your doctor may or may not recommend this procedure for your situation.

What to Expect Before, During, and After the Procedure

Knowing what happens at each stage of the Watchman procedure can reduce anxiety and help you prepare. The process typically unfolds over several months.

Before the Procedure: Your doctor will order several tests to prepare. An echocardiogram creates detailed pictures of your heart and measures your LAA. A CT scan or MRI may also be performed to create a three-dimensional map of your heart. These images help your doctor plan exactly how to position the device. You will also have blood work done to check how well your kidneys and liver are working. Your doctor will review all medications you take and may ask you to stop certain ones before the procedure, particularly blood thinners. You will receive instructions about when to stop eating and drinking before the procedure, usually the night before. On the day of the procedure, you will go to a hospital or specialized cardiac center.

During the Procedure: You will be given sedation to help you relax, and local anesthesia will numb the area where the catheter is inserted, usually in your groin. You will be awake but drowsy during the procedure. Your doctor will insert a thin tube (the catheter) into a blood vessel in your leg and guide it to your heart. Special imaging helps your doctor see inside your heart in real time. Once the Watchman device is in the correct position inside the LAA, your doctor will release it. The device will expand to fit the opening. Your doctor will check that the device is positioned well and that there are no complications. The entire procedure usually takes 60 to 120 minutes. You will then be moved to a recovery area where nurses will monitor your heart rhythm and vital signs as the sedation wears off.

After the Procedure: Most people go home the same day or stay overnight for observation. You may feel some soreness where the catheter was inserted. Your doctor will provide pain medications if needed. For the first few weeks, you should avoid heavy lifting and strenuous exercise. You will need to take antibiotics for a short time to prevent infection. You will also take aspirin and another blood thinner for several months. This medication helps prevent clots from forming on the device while the tissue inside your heart grows over it. Most people can return to normal activities within a week or two, though this varies.

Follow-up visits are crucial. You will have echocardiograms at 45 days, six months, and one year after the procedure to make sure the device is working correctly and that it has sealed properly. Your doctor will also monitor you for any signs of complications.

Practical Takeaway: Understanding the timeline and what happens at each stage—from pre-procedure testing through recovery to follow-up care—helps you mentally prepare and know what to expect.

Success Rates and What Research Shows

Clinical trials and real-world studies provide information about how well the Watchman device works and what risks are involved. Looking at this research can help you understand the potential benefits and drawbacks.

The major clinical trial for the Watchman device, called the PROTECT AF trial, followed over 700 patients for several years. The trial compared people who received the Watchman device to people who took warfarin (a blood thinner) to prevent strokes. The results showed that the device was effective at preventing strokes. Over nearly four years, the device group had a slightly lower rate of stroke, blood clots, and cardiovascular death compared to the warfarin group. This was notable because the device provides a permanent solution, while blood thinner medications must be taken daily for life.

A follow-up trial called PREVAIL looked at newer versions of the Watchman device. This study also showed good results, with stroke prevention similar to that of blood thinners. Importantly, the newer version appeared to have fewer complications during and shortly after the procedure compared to earlier versions of the device.