ACC21 Study Supports LAA Occlusion at the Time of Cardiac Surgery in Patients With Atrial Fibrillation

Recently I spoke to a cardiothoracic surgeon in Florida who was going to be performing a bypass operation on a patient of mine. To my surprise, despite the patient never having had atrial fibrillation, the surgeon informed me that he was planning to operate on the patient’s left atrial appendage, telling me “Down here, we close the left atrial appendage of all patients undergoing heart surgery.” 

For many years now I have been frustrated with the lack of evidence supporting left atrial appendage occlusion (LAAO), a procedure that many surgeons were adding on to the cardiac valve or coronary bypass operations on patients I had referred to them. After I spoke to the Florida surgeon I realized that LAAO in patients who had never had atrial fibrillation was becoming increasingly utilized.

As one who visualizes the LAA routinely by transesophageal echocardiography I see how important the pump function of this appendage is to overall atrial function and how its pump function is essentially eliminated in postoperative patients. What damage was removing or obliterating the LAA doing to overall cardiac function? I even created a website with the URL “I am Joe’s Left Atrial Appendage”, attempting to drum up sympathy for this abused portion of the heart.

Of course, there is strong evidence that the LAA is the major nidus for thrombus formation when the heart persists in atrial fibrillation. This still image from a TEE shows an enlarged LAA without thrombus.

Whereas this video shows a nasty clot wiggling in an enlarged, dysfunctional LAA.

If that clot decides to leave the appendage it launches into the arterial circulation and floats along until it reaches an artery too small to traverse at which point the organ supplied by that artery, deprived of oxygen begins to die. If that organ is the brain that death is called a stroke.

At the American College of Cardiology’s 2021 Scientific Sessions yesterday a hugely important, practice-changing, randomized trial finally provided evidence that LAAO performed at the time of concomitant heart surgery in patients with atrial fibrillation is safe and beneficial.

Richard Whitlock, professor of surgery, at Canada’s McMasters University organized this landmark study (the LAAOS III) and presented the findings. The results were published simultaneously in the New England Journal of Medicine. Twenty-seven countries participated and recruited 4811 patients who were randomized to LAAO versus no LAAO.

Surgeons utilized a variety of closure techniques:

Patients were followed for 3.8 years on average with the primary outcome being ischemic stroke or systemic embolism.

The patients were evenly matched in both groups with average age of 71 years, CHADS2 score of 4.2, permanent afib 29% and 2/3 male.

CABG alone was performed in 20% with 2/3 undergoing concomitant valve procedure.

Overall, 77% of patients were taking oral anticoagulants.

Here’s the Kaplan-Meier curve for the primary outcome:

There was a significant reduction of 33% in the primary endpoint which occurred in 4.8% of LAAO patients versus 7.0% of non-LAAO patients

There was no signal of increased heart failure risk although the 7% rate of hospitalization for heart failure at 3.8 years was improbably low raising the possibility of failure to capture all these episodes.

To my surprise, there was no increase in reoperation for bleeding or 20 day mortality. LAAO procedure resulted in a 6 minute increase of bypass time.

This study now provides support for performing LAAO on high CHADS2 score afib patients at the time of cardiac surgery. Please note that the majority of these patients stayed on oral anticoagulants through the duration of the study and the trial does not support removal of OAC in this situation.

Also, it does not support the approach the surgeon in Florida follows in patients who do not have a history of atrial fibrillation. There are no data supporting that approach.

Appendiceally Yours,



14 thoughts on “ACC21 Study Supports LAA Occlusion at the Time of Cardiac Surgery in Patients With Atrial Fibrillation”

  1. I suffered from pretty severe recurring Afib. I’d had two previous ablutions. The first held for several years, the second not so much. Amiodorone has kept me palpitation-free for over a year now. I like it, but what about the longterm concerns. Is it possible for me to use it for several years without necessarily suffering longterm consequences?

    • amiodarone is a great drug-very safe and effective if monitored and dosed appropriately.
      I’ve written about it on my blog several times. If you have trouble using the search function to find those posts let me know

  2. Thank you for explaining that. I’m curious if this has been studied, your point on baseline stroke volume output before and after LAAOS and to what degree it changes. It might be worth doing an RCT if LAAOS frequency increases due to this study.

  3. Great post ( I was curious if you were going to post something about LAAOS after your twitter post on your CABG patient in Fl, thank you for doing that)

    You had also mentioned in the post that you see how important the pump function of the LAA is to overall atrial function and if I remember correctly you mentioned there is endocrine function too, does the LAA serve any other functions?

    The pump function issue is interesting, from your perspective do you think elective occlusion/removal could precipitate atrial dysfunction or myocardial dysfunction?

    I thought it was interesting that bypass on average lasted 6 minutes longer, I could see other complications arising like risk for infection, post surgical bleeding (regarding amputation of LAA) for something elective in non HF patients. With AF patients those risks might be warranted but with non AF patients, it seems iatrogenic.

    • Christian,
      Some have speculated that the LAA adds to the compliance of the left atrium, making it more able to handle increased volume input at a lower pressure.
      My concern is that obliterating/resecting the LAA will reduce atrial function , thereby lowering the “priming of the ventricular pump” prior to contraction and thus lowering stroke volume output.
      In general, it is felt that shorter bypass times/pump runs lowers bleeding risks/encephalopathy risks. How much risk an extra 6 minutes adds is debatable and speculative but the shorter time the better.

  4. The article on Healthline which I quoted mentioned a procedure for removing the LAA without the need for open heart surgery. The article did not elaborate. Do you have any information about this?

    • The LAA “closure” or “obliteration” can be approached using the catheter-based Watchman device which is FDA approved for patients who are very high risk for taking oral anticoagulants
      There are also surgical techniques like the Lariat which can be performed on a beating heart by a thoracotomy approach but I don’t recommend this.

  5. With regard to the strokes that occurred in those with LAAO. Would they be strokes not associated with AFIB or can AFIB strokes occur even if the LAA is closed up.

  6. What is your opinion on the use of amiodorone when ablation has failed to prevent recurrence of PAF?

  7. I wish every article on AF would analyze subsets of Paroxysmal AF vs Persistent AF vs Permanent AF with the study. These 3 groups are not the same and the application of data from on to the other is inappropriate, in my view.

    • In this study 29% of patients had permanent atrial fibrillation.
      That means 71% had either Paroxsymal or Persistent AF.
      The difference between Par and Per AF is vague and somewhat arbitrarily defined.
      For example, a patient who had 8 days of afib 10 years ago which was terminated after a cardioversion and has not had a single episode since would be classified as Per AF.
      On the other hand a patient who has 5 day episodes once a month is considered paroxsymal. These patients will likely have radically different outcomes following LAAO but the designation of Par vs Per doesn’t add much to understanding the population that benefits best.


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