In 30% of A-Fib patients, the LAA was the only structure that had A-Fib signals.
In his presentation, Dr. Dhanunjaya Lakkireddy said after the Pulmonary Veins (PV)s, “the LAA is the most common source of (A-Fib) focus triggers and other A-Fib signals.” He further stated that in patients over 70 years old, especially women, the LAA plays a more important role as the source of A-Fib signals. Removing or closing off the LAA reduces the pumping volume of the left atrium by 15% to 30%…Read more.
AF Symposium 2015
Should the Left Atrial Appendage (LAA) be Removed in Patients With A-Fib?
by Steve S. Ryan, PhD
Leading doctors and researchers have pointed out the importance of the Left Atrial Appendage (LAA) particularly when ablating persistent A-Fib. In the Bordeaux group’s Five-Step Ablation Protocol for Chronic A-Fib, after isolating the Pulmonary Veins (PVs), their next step is to look for A-Fib signals coming from the LAA. In 2010, Dr. Andrea Natale and his colleagues showed that in 30% of A-Fib patients, the LAA was the only structure that had A-Fib signals. (Circulation 2010.)
In his presentation, Dr. Dhanunjaya Lakkireddy from the Un. of Kansas Hospital in Kansas City, MO, confirmed these findings. After the PVs, “the LAA is the most common source of (A-Fib) focus triggers and other A-Fib signals.”
In Older Patients the PVs Have No A-Fib Signals
He further stated that in patients over 70 years old, especially women, the LAA plays a more important role so much so that the PVs are often silent.
How Removing the LAA Affects Left Atrium Pumping Volume
Removing or closing off the LAA reduces the pumping volume of the left atrium by 15% to 30%. But after the LAA is removed, the overall left atrium volume improves.
Removing The LAA Reduces Natriuretic Peptides―But The Heart Compensates Over Time
The LAA is responsible for neuroharmonal changes such as natriuretic peptide levels (i.e., regulates the amount of sodium in the urine) which are important for bodily functions such as thirst. When the LAA is removed, natriuretic peptide levels go down. But Dr. Lakkireddy’s research shows that over time these levels normalize. Other heart areas such as the right atrium compensate and produce more natriuretic peptides to make up for what the LAA used to produce.
Removing the LAA Lowers Blood Pressure
Removing or closing off the LAA often improves blood pressure by dropping epinephrine (adrenaline) levels and lowering (“down-regulating”) the
renin-angiotensin system (hormone system that regulates blood pressure and fluid balance).
Removing the LAA Improves Recurrence Rates
Dr. Lakkireddy found that removing or closing off the LAA at the same time as a catheter ablation for A-Fib reduces recurrence rates by 29%.
Why LAA A-Fib Signal Sources in Older People—Why Do PVs Go Silent?
One of the most important findings of Dr. Lakkireddy’s research is that in older people the LAA is the most important source of A-Fib signals, so much so that the PVs are often silent. This is counter-intuitive and hard to understand. If, as we know from years of previous research, A-Fib usually starts and is most often found in the PVs, why do the PVs go silent and A-Fib activity mostly move to the LAA in older people? What is the physical or chemical mechanism that causes this major change?
Sea-Change in Ablation Strategy
Dr. Lakkireddy’s presentation was the most important and ground-breaking for older A-Fib patients. It should change the way ablations are performed on older people. If you are over 70 years old, in persistent A-Fib and aren’t very active, you must seek out EPs and centers who understand and ablate the LAA. Most EPs don’t even look at the LAA as possible A-Fib signal sources. Don’t rely on your local EP to learn about this research and adopt any requisite new ablation strategies.
In Older A-Fib Patients the LAA Should be Removed
It certainly looks like, in the case of older people with A-Fib, the LAA should be removed by an occlusion device (either the Lariat or by surgery [AtriClip]). In addition to the known benefit of reducing A-Fib stroke risk (90%-95% of A-Fib clots come from thee LAA), the LAA is a major and often the only source of A-Fib signals in older people.
Little Downside to Removing the LAA
And according to Dr. Lakkireddy, there is very little downside to removing the LAA.
Blood pressure goes down, over time natriuretic peptide levels return to their pre-LAA levels as the heart compensates, the lost LA pumping volume does improve, and recurrence rates are reduced when the LAA is removed.
Older people who are less active may not even notice the loss of LAA pumping volume or the reservoir or surge effect of the LAA. (On the other hand, an active athletic senior may be affected by the loss of pumping volume if the LAA is removed.)
LAA Can Be Removed Before or After an Ablation
In the case of a catheter ablation for A-Fib, it may not be necessary to remove the LAA at the time of the ablation. Since it is a safer procedure than even an A-Fib ablation, the LAA could be removed three months before or after a catheter ablation.
Last updated: Friday, March 6, 2015
by Steve S. Ryan, PhD, February 2015
The heart’s Left Atrial Appendage (LAA) has emerged as an important factor in the source of A-Fib signals. So much so, that doctors and researchers from around the world gathered for a two-day Symposium devoted exclusively to the LAA on February 6-7 at the Marina del Rey Marriott Hotel in Marina del Rey, CA.
Overview—First Impressions & Brief Reports
“Closing Off the LAA Has No Adverse Effects”
This Symposium was unique in that Electrophysiologists, Interventionalists and Surgeons were featured speakers and attendees. Dr. James Cox, inventor of the original Cox Maze operation, both presented a report and participated in a debate “Who Should Perform LAA Occlusion/Exclusion Procedures? A 3-Way Debate with a Surgeon, EP and Interventionalist.” In Dr. Cox’s talk he stated that cutting out the LAA has no adverse effects. This is a very powerful statement coming from someone with his years of experience.
AtriClip In Action
Dr. Cox said that the AtriClip closure device was the safest compared to staples and sutures. We were privileged to see two recorded operations using the AtriClip which were fascinating to watch. The surgeon opened up the pericardium sack and inserted the AtriClip over the LAA. In the first case he used what looked like two pencil eraser probes to poke and prod the LAA into the jaws of the AtriClip.
In the second case the surgeon inserted sutures into the LAA and used them to pull the LAA through the AtriClip opening. Once the AtriClip closed off the LAA, the closure looked very complete and secure. Both surgeons did not sew up and close the pericardium opening they had made to get to the LAA. This was surprising to me, but I later learned that this is standard procedure during such surgery to not close or stitch up the pericardium sack.
Watchman May Win FDA Approval
In my earlier brief reports on the Orlando AF Symposium, based on the recent research and the FDA presentation, I said the Watchman device probably won’t be approved in the US.
I’m happy to say that I am most likely wrong. The Watchman may be approved by the middle of this year. One presenter described how the FDA chairman talked with several people who were going to Canada to have the Watchman device installed. He seemed embarassed that the Watchman was available everywhere in the world but not in the US and said that it has to be approved.
Other doctors I talked with at the LAA Symposium were of the same opinion. Presenters described how clinical trials for other LAA closure devices were on hold so that they could get approved in comparison to the Watchman (Non-Inferiority Trials). Dr. Dhanunjaya Lakkireddy of the University of Kansas Medical Center said that we are at a “tipping point” for the (A-Fib) industry.
Lariat Live Case
We were privileged to watch a live case from Cedars Sinai in which Dr. Saibal Kar and his colleagues inserted a Lariat device to close off the LAA in a patient. From outside the heart Dr. Kar inserted a magnet-tipped catheter through the diaphragm so that it arrived at the base of the LAA. Then from inside the heart he inserted another magnet-tipped catheter to the base of the LAA where the magnets joined and formed a rope-like structure.
Using this rope-like link he inserted a catheter with the Lariat II device which followed this rope-like link till it reached the LAA. He then unfurled the Lariat snare or noose-like device which he manipulated over the base of the LAA. But there were problems. It was hard to get all the folds or pouches of the LAA in the Lariat snare.
In most Lariat procedures, they use a balloon inside the heart to expand the LAA so that the lariat noose can more easily fit over it. Inserting the Lariat seemed like a somewhat tricky procedure to me, and is certainly more complicated than inserting a Watchman device.
Having to work from both outside and inside the heart and using balloons and catheters with magnet tips isn’t something the average EP or Interventionalist is used to doing. As Dr. Andrea Natale commented, the Lariat procedure needs skill and expertise. Though Dr. Natale didn’t say this, there are few centers and doctors with the experience, skill and expertise necessary to successfully insert the lariat device.
LAA Structures are Different and Unique
Previous research has postulated that the LAA has four basic structures:
1. Chicken-wing (48%)
2. Windsock (19%)
3. Cactus (30%)
4. Califlower (3%)
The Chicken-wing is the easiest to tie off with the Lariat, while the Califlower can be quite difficult. Also, sometimes the LAA is virtually inaccessible, because it is buried behind other heart structures.
Dr. Jacqueline Saw of Vancouver General Hospital certainly surprised me by showing five more different LAA shapes which she named:
5. Elephant trunk
8. Whale’s tail
It seems that every LAA is different and unique in structure, like snowflakes. This may be very important in our understanding of the LAA.
Dr. Shaw also described how the LAA Orifice Opening can have very different shapes:
1. Oval (68.9%)
2. Triangular (7.7%)
3. Foot-like (10%)
4. Waterdrop-like (7.7%)
5. Round (5.7%)
She also described how Cardiac Computed Tomography Angiography [CCTA]) imaging is used to measure the diameter and depth of the LAA. Addition measurements include the internal LAA structures such as lobes, muscle ridges, trebeculations and sharp bends.
These internal structures may influence or hinder the placement of LAA occlusion devices.
CCTA imaging can also be used after an occlusion device (i.e. Lariat or Watchman) is implanted to inspect and detect gaps or leaks.
Last updated: Friday, March 6, 2015