The Role of the Left Atrial Appendage (LAA) & Removal Issues

By Steve S. Ryan, PhD

In the first trimester or two of our time in the womb, The Left Atrial Appendage (LAA) was originally our left atrium (LA). When the final real Left Atrium (LA) formed gradually from the conjunction and evolutionary development of the four pulmonary veins, the actual LA chamber grew and ballooned out, pushing the smaller remnant LA up to the left top of the Left Atrium where it became known as the Left Atrial Appendage (LAA) with its own functions and behaviors.

But as we age and as heart disease/A-Fib, etc. start to set in, the LAA can turn into “the most lethal, no longer essential appendage in the human anatomy,”according to Shannon Dickson of afibbers.org.

One considered advantage of the Mini-Maze operations is that the Left Atrial Appendage (LAA) is closed or cut off. Most A-Fib blood clots which cause stroke come from the Left Atrial Appendage. By closing off the LAA, most but not all risk of stroke is eliminated even if you are still in A-Fib. Removing the LAA can reduce the risk of stroke from 7 percent to 5 percent, according to Dr. Richard Whitlock,

Failure to Completely Close Off the LAA is Common

According to Dr. Marc Gillinov of the Cleveland Clinic, staplers “can be hard to apply to the appendage and tend to leave a little cul-de-sac and also cause bleeding and tearing, so they are not particularly safe or effective.”²

However, the AtriClip device (FDA approved June, 2010) makes it much easier for surgeons to close off the LAA during open heart surgery. The surgeon positions the rectangular-shaped device around the LAA and then closes it like a clamp. Blood no longer flows into and out of the Left Atrial Appendage.³

AtriCure has developed a version of the AtriClip which can be used in Mini-Maze surgery.

Should the LAA be routinely cut out, stapled shut or closed off in all A-Fib patients?

The rationale for closing off the LAA is that, in case the operation fails which happens occasionally, the patient is still protected from having an A-Fib stroke. 90%-95% of A-Fib strokes come from clots which originate in the LAA. In A-Fib, blood stagnates in the LAA and clots tend to form.

VIDEO: Watch an endoscopic view of stapling and removal of the Left Atrial Appendage  (1:34 min.) Go to video->

Another important consideration, even if a person is no longer in A-Fib, is that closing off the LAA may still prevent a stroke. The LAA is where most clots originate. If a surgeon is already working on the heart, why not close off the LAA and reduce the patient’s chance of having a future stroke? (If a surgeon didn’t close off the LAA, they could be sued if a patient later had a stroke, even if the patient was no longer in A-Fib.) Life (no stroke) is more important for most people than a possible reduced exercise intolerance.

In the future even people without A-Fib may have their Left Atrial Appendage closed off if it prevents or reduces the risk of a stroke. This may become a way to prevent stroke in older people, particularly women, who are more at risk of stroke as we age. There are currently a variety of devices, surgical and non-surgical, which can do this. LAA closure may become an important new way to reduce strokes, particularly in the elderly.

Functions of the Left Atrial Appendage

But some question the need or benefit of removing the Left Atrial Appendage (LAA) if someone is no longer in A-Fib. For a patient made A-Fib free, would their heart function better or more normally if they still had their LAA? In the words of Dr. Pierre Jais of the Bordeaux Group at the 2020 AF Symposium, “We have ablated too much…Those patients when they have the (Left Atrial) Appendage taken out, they have very poor residual LA (Left Atrium) function. I don’t want that to happen anymore. If we can avoid it, I think we should.” Dr. Jais later added, “Sinus rhythm is by definition superior to persistent A-Fib. But the best ablation strategy is the one that restores sinus rhythm at the least tissue cost, thereby preserving as much as possible the LA function.”

LAA Functions Like a Pressure Release Valve

Also, the LAA functions like a reservoir or decompression chamber or a surge tank on a hot water heater to prevent surges of blood in the left atrium when the mitral valve is closed.⁴ Without it, there is increased pressure on the pulmonary veins and left atrium which might possibly lead to heart problems later.

Losing the LAA Reduces Blood Pumped by the Heart

Cutting out or stapling shut the LAA also reduces the amount of blood pumped by the heart and may result in exercise intolerance for people with an active life style. (In dogs the LAA provides 17.2% volume of blood pumped.⁵) This is usually not a problem for patients with Persistent (Chronic) A-Fib, whose LAA has stopped contracting along with the fibrillating atrium. Cutting out or stapling shut the LAA won’t affect their cardiac output.

But this may not be the case for patients with Paroxysmal A-Fib who still have large amounts of normal rhythm and whose LAA still functions normally.

But would a non-functioning LAA return to normal when someone with, for example, longstanding persistent (Chronic) A-Fib becomes A-Fib free?

I’m not aware of any surgeons (or EPs) who do pre- and post-LAA closure measurements of exercise ability, heart pumping function, etc. with and without the LAA. 

Losing the LAA May Worsen Blood Pressure

The LAA also has a high concentration of Atrial Natriuretic Factor (ANF) granules which help to reduce blood pressure.⁶ Some preliminary research indicates that when the LAA is closed or cut off, the Right Atrial Appendage produces more ANF to compensate for the lost of the LAA.

Editor’s comment: If you are thinking of having a Cox Maze or Mini-Maze, discuss removing the LAA with the surgeon. Ask if they close off the Left Atrial Appendage and with what: sutures, stapler or the AtriClip.

Whitlock, Richard. A simple surgery reduces the risk of stroke in people with atrial fibrillation. Bottom Line Health, August 2021 Vol 35/No 8, p. 2.

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Last updated: Monday, July 19, 2021

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