A Watchman is a device that can help prevent blood clots from leaving the heart. However, the procedure to insert the device carries its own risks. These risks can include cardiac tamponade and ischemic stroke.

The Watchman device functions to reduce the risk of stroke.

During a Watchman procedure, doctors operate to install the device into someone’s heart. This article discusses the procedure’s possible risks, how the procedure works, who it is for, and its possible benefits.

A surgeon performing a Watchman procedure after considering the risks.Share on Pinterest
The deployment and placement of the Watchman device is controlled by a small knob at the end of a catheter, seen here during a procedure on patient Paul Rice in an operating room at Maine Medical Center on Thursday, September 21, 2017. Image credit: Portland Press Herald/Getty Images

To place the Watchman into the heart, doctors must operate.

All operations have a risk of complications. Possible complications of surgery generally include:

Researchers have produced different estimates of complication rates for the Watchman procedure.

A 2021 study found that, out of the estimated 43,802 Watchman procedures doctors performed in the United States between 2015 and 2019, complications arose in 7.3% of cases.

The mortality rate for these procedures was 0.4%.

Additionally, in a 2018 review, researchers looked at the complication rates in about 1,025 Watchman procedures that happened between 2013 and 2015 in the U.S.

The authors state that in 2.8% of cases, serious complications arose within 7 days of the Watchman procedure.

They estimated a mortality rate of 0.3% within 7 days of the Watchman procedure, similar to the figure in the 2021 study.

As with complication rates more broadly, scientists are unsure about this procedure’s exact mortality rate.

The Watchman procedure has several possible complications, some more likely than others.

Cardiac tamponade

During surgery, doctors can sometimes cause trauma to the heart or surrounding tissues.

This can lead to a buildup of fluid around the heart. When this kind of fluid buildup causes a reduction in heart function, medical experts call it a cardiac tamponade.

A 2020 case study states that cardiac tamponade is the most common complication of the Watchman procedure. The authors mention that in one trial of the Watchman device, cardiac tamponade occurred in 4.3% of cases.

Accidental heart puncture

According to Watchman’s website, the procedure could cause a cardiac puncture.

A cardiac puncture is a serious injury to the heart. However, there is currently no evidence of heart punctures arising from the Watchman procedure.

Air embolism

An air embolism occurs when air enters the blood, forming a bubble. After traveling around the circulatory system, the air bubble could block a vein or artery. If this blockage occurs in the brain, it could cause a stroke.

Air embolism can sometimes occur during the Watchman procedure. This is because surgeons insert the Watchman device through the veins.

There is evidence that air embolism has killed at least 1 individual during the Watchman procedure. Around 5 in every 449 Watchman procedures may cause an air embolism-induced stroke.

Allergic reaction

According to Watchman’s website, the device may sometimes cause an allergic reaction in the heart. However, scientists have not yet found any evidence of this complication occurring.

Scientists do know that allergic reactions to heart implants can sometimes occur. For instance, heart tissues can become hypersensitive to the coating of pacemakers.

However, this reaction is extremely rare, affecting around 571 per million people.

Major bleeding

Watchman’s website also discusses the possibility of excessive bleeding. This could occur from trauma to the blood vessels or heart as a result of surgery.

However, scientists have not yet observed any major bleeding events resulting from the Watchman procedure.

Ischemic stroke due to device thrombosis

It is possible for the Watchman device to induce device thrombosis. Thrombosis occurs when a blood clot, or “thrombus,” blocks an artery or vein. If the thrombus causes a blockage within the brain, this may lead to a stroke.

Device thrombosis occurs when device-implanting surgery induces blood clotting. According to a 2019 case study, the risk of device thrombosis during the Watchman procedure is between 3.7% and 6.6%.

As the Watchman website explains, the Watchman implant is for people who have an atrial fibrillation that is not the result of a heart valve problem.

Doctors call this condition nonvalvular atrial fibrillation (NVAF).

In NVAF, blood clots can form in a part of the heart called the left atrial appendage (LAA). The Watchman device closes off the LAA and prevents blood clots from leaving the heart.

While blood thinners are the standard treatment for NVAF, some people cannot take them. Taking blood thinners regularly also presents risks, such as excessive bleeding from cuts and falls.

The Watchman device can be a good alternative to blood thinners in some people.

According to a 2018 review, the Watchman may cause an 84% reduction in the risk of ischemic stroke in people with NVAF. It may also reduce the risk of major bleeding by 48%.

Additionally, undergoing this procedure means that a person with NVAF does not have to regularly take blood thinners, which carry their own risks and side effects.

This section answers some frequently asked questions about the risks of the Watchman procedure.

What is the death rate for the Watchman procedure?

Researchers have found the death rate for the Watchman procedure to be as high as 0.4% in some samples.

However, researchers are unsure of the overall mortality rate for the procedure.

Is the Watchman worth the risk?

Watchman devices can be worth the risk for people with NVAF. This is because the device can reduce the risk of stroke by 84% and the risk of major bleeding by 48%.

However, complications can occur. The risks of the procedure will depend on a person’s overall health, but possible risks include cardiac tamponade and device thrombosis.

For those who are not eligible for a Watchman device — such as those who are too vulnerable for a heart procedure — it may be better to take blood thinners.

When weighing the pros and cons of the Watchman procedure, an individual should seek expert advice.

Who should not have the Watchman procedure?

A person should not receive a Watchman implant if they:

Additionally, people who are eligible for oral anticoagulant therapy may have an increased risk of experiencing complications from the Watchman procedure.

By sealing off the LAA, the Watchman device can greatly reduce the risk of stroke in people with NVAF.

However, this device can cause complications. Some of these, such as air embolism and device thrombosis, can cause strokes. Cardiac tamponade is another possible complication.

Watchman devices provide a useful alternative to the potential lifelong use of blood thinners. However, an individual with NVAF should carefully consider the risks and benefits of both therapies. Doctors can assist in this process.