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