By Steve S. Ryan, PhD, Updated August 2018

For Atrial Fibrillation patients who can’t or don’t want to take anticoagulants, closing off the Left Atrial Appendage (LAA) is an option. The LAA is a small pocket of heart tissue located above the left atrium. You are typically looking at an occlusion device such as the Lariat or the Watchman (surgical removal is also an option) to close off or remove the LAA. The Lariat is relatively new, so, how does it compare to the Watchman?

About the Lariat

The Lariat occlusion device

The Lariat device is a noose-like device which is slipped around the LAA. This ‘lasso’ is then tightened, and eventually the tissue dies and shrivels up (like a grape into a raisin). In effect, the Lariat chokes off the LAA and eliminates it as a source of A-Fib signals. (For more on the Lariat see my article: Tech & Innovations: Lariat II.)

A serious problem with the Lariat is described as “the gunny-sack effect”. The LAA heart tissue between the lariat lasso atrophies and becomes thinner. As with a gunny sack, the multiple tight folds begin to loosen and unravel slightly leaving a hole. If the hole is large enough, blood may flow into and out of the dead LAA possibly carrying with it dead tissue remnants into the blood stream which can cause clots and strokes. The number of clot/strokes reported so far is very small compared with the total Lariat cases worldwide.

Easily Fixed if Discovered

Once this hole or leak is discovered, it’s relatively easy for the EP to fix by closing it off using one of several occluder devices.

About the Watchman Device

The Watchman occlusion device

The Watchman device, in contrast, is basically a plug that closes off the LAA from the inside of the LAA. It’s inserted via catheter, positioned and inflated. It ‘screens’ any clots from leaving the LAA. Eventually, heart tissue grows over the area.

But due to the typical non-symmetrical opening of the LAA, there can be leakage when the Watchman is installed due to the ‘edge effect’ (the device not always fitting perfectly). The leakage, though, isn’t generally large enough to permit clots to escape from the LAA into the heart. The incidence of leaks is around 30% to 35% depending on which research you look at.

Clots can also form on the surface of the device site. Therefore, after the Watchman is installed, patients are put on blood thinners for some time. (The risk of clot formation on the device site is around 4.5%, which is comparable to the risk of patients on oral anticoagulation.)

Eventually heart wall tissue grows over the occluded surface, with the exception of the bare metal screw visible after the Watchman is installed. But  this does not necessarily block electrical activity coming from the LAA, so the edges of the LAA may have to be ablated (which can be challenging).

Solution: Ablation First, Then Watchman

To avoid this last scenario (A-Fib triggers coming from the LAA), your EP will typically recommend you first get a catheter ablation to isolate the LAA. Later, after the ablations scars (lesions) have healed, the Watchman can then be installed, if necessary.

The Watchman device and the Lariat are FDA approved.

Why One Patient Chose the Lariat

Shannon Dickson, editor of THE AFIB REPORT, says he chose the Lariat “after already having had a successful LAA isolation ablation a year earlier which had eliminated the last remaining trigger source of a periodic LAA-based tachycardia. The reason I chose the Lariat in spite of having no more arrhythmia at all after that LAA isolation procedure, was to not only be able to stop all OAC drugs, but to add an extra measure of insurance that my LAA could never again become a source of any future arrhythmia. The prior successfully ablated LAA trigger source could never reconnect at some point and start the whole mischief again.

By fully ligating the LAA with a successful Lariat or AtriClip procedure, the added bonus of full electrical isolation of the LAA is added to the obvious vascular isolation as well.

The Watchman is designed to prevent LAA-based thromboembolic events, but does not electrically isolate the LAA. As such, any Watchman candidates who still have active LAA-based triggering should strongly consider getting an LAA isolation ablation prior to the Watchman procedure.”

Shannon considers the LAA “the most lethal appendage in the human anatomy.”

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Questions About the Lariat

The Lariat is a relatively new procedure with many questions from patients. Here are several of these questions with my thoughts after each one.

Q: “What are the long-term effects of leaving dead heart tissue to dissolve and become reabsorbed on the left atrium and in the pericardium sack?” These are yet to be fully studied. Most of the time the LAA remnant shrinks and becomes a fibrous, hardened tissue.

Preliminary data suggests that the hormones normally produced by the LAA are eventually re-produced by the Right Atrial Appendage (RAA) (it’s not talked about much, but yes, there is a Right Atrial Appendage too) and other parts of the heart.

Q: “If there is any type of hole left, will blood from the heart eventually leak into the pericardium sack once the LAA is gone?”

Most likely not. This hasn’t been an issue in all the years of surgical staple or suture ligation of the LAA. When the LAA shrinks and dissolves, it may form a permanent cap over any remaining hole. The perfect analogy here may be the umbilical cord after it is tied. The blood flow ceases and it becomes a hardened, fibrous structure.

Q: “What actually happens to the LAA when it dies and deteriorates?”

We know that the LAA shrivels up (like a grape into a raisin) and eventually disintegrates. On the inside of the heart where the LAA mouth was, heart tissue eventually grows over this now-closed mouth or opening.

Q: “How long does this process take?”

In general it takes around three to six months for heart tissue inside the heart to grow over the closed-off mouth of the LAA. On the outside of the heart, the LAA shrinks to a final-state cap over the closed-off LAA mouth in about a year or slightly longer and is somewhat variable per person.

Q: “How does this dead tissue affect the rest of the heart and body?”

Most likely this dead LAA tissue won’t have a bad effect on the rest of the heart and body. In the experience of surgical stapling or sutures to close off the LAA, there hasn’t been a body of evidence of late issues or complications. Though again, it’s too early in the experience of the Lariat procedures to say this definitively.

Q: “Some say the LAA dead tissue is simply absorbed by the body. How does this happen?”

More study needs to be done to identify and define the actual processes and time table, but previous surgical studies and autopsies indicate that the dead LAA disintegrates and is eventually re-absorbed by the body.

The Bottom Line

The Lariat’s “Gunny-sack” effect described above is relatively rare and is easily fixed. It shouldn’t be a major concern if you need to have a lariat device installed to close off your Left Atrial Appendage. Just make sure your EP checks the Lariat for leaks every three months during the first year after you get it installed. If your doctor doesn’t or won’t do that, find someone else to install the Lariat.

In spite of the small risk of clotting with the Lariat, if you can’t tolerate taking anticoagulants, it’s still the procedure of choice (the Watchman device requires 6 weeks of anticoagulants post-procedure). But it’s a more complicated procedure than installing a Watchman. You should only go to an EP experienced at installing the Lariat.

People chose the Lariat because it’s a welcome alternative to a lifetime on blood thinners (anticoagulants). 90%-95% of A-Fib clots come from the LAA. Closing off the LAA isn’t an absolute guarantee one will never have an A-Fib clot or stroke, but it comes close. (Neither are today’s anticoagulants.)

Overall, most people who have a Lariat installed are older with long-term persistent A-Fib, or with long-term paroxysmal A-Fib with the LAA as the prime driver of their arrhythmia.

If you are worried about what happens to your LAA when it dies and disintegrates, and how it might affect your body and overall health, we have no evidence or experience that it is a long-term health risk.

Which is Better―The Lariat or the Watchman?

There haven’t been any head-to-head comparisons of the Lariat and Watchman. So far, reaching conclusions about the superiority of one device versus the other cannot be made at this time. The choice of device has to be made based on the individual needs of a particular patient.

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Last updated: Saturday, April 13, 2019

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