Minimally Invasive TT Maze Surgery Advances AFib Treatment

Keck Medicine of USC cardiothoracic surgeon Jonathan Praeger, MD, explains how a less-invasive approach to epicardial ablation helps resolve longstanding persistent AFib.

Endocardial ablation has a successful record in resolving paroxysmal atrial fibrillation (AFib). But for patients with longstanding persistent AFib, the procedure — in which an electrophysiologist creates scar patterns on tissues inside the heart to block the faulty electrical signals disrupting its rhythm — isn’t as effective. 

In such cases, surgical epicardial ablation on tissues outside the heart delivers better results, and it’s often combined with endocardial ablation in a hybrid approach. 

But while traditional epicardial procedures require open-heart surgery, a less-invasive method called totally thoracoscopic (TT) maze is improving outcomes for patients with longstanding persistent AFib. 

Jonathan Praeger, MD, a cardiothoracic surgeon with the USC Cardiac and Vascular Institute, part of Keck Medicine of USC, provides an example of how he successfully performed the surgery on a 71-year-old California patient. He answers questions about TT maze and why it may be precisely what longstanding persistent AFib patients need. 

Why doesn’t endocardial ablation resolve longstanding persistent AFib as successfully as it does paroxysmal AFib? 

The mechanisms behind paroxysmal and longstanding persistent AFib are different. 

The triggers causing paroxysmal AFib come around the cuffs of the pulmonary veins, which is why electrophysiologists have success treating it with pulmonary-vein isolation. But as you start getting remodeling and fibrosis in the atrium, these changes sustain the macro reentry loops — the continuously rotating electrical circuits in the heart — that drive longstanding persistent AFib. And that’s a much more complex problem to solve. 

Is this one reason why longstanding persistent AFib treatment has shifted toward a hybrid approach? 

Yes. The one-time success rate for restoring this population to normal sinus rhythm and keeping them there using endocardial ablation alone is in the 30% range. That led us to ask how we could do better. Data show that a hybrid approach, where a surgeon works on the outside of the heart with epicardial ablation and an electrophysiologist works on the inside, seems to have better outcomes. 

The TT maze method that you performed on this patient differs from the standard sternotomy in that it lets you access the heart via incisions between the ribs rather than by cutting the sternum. Why is this preferable? 

A lot of patients we bring into the operating room for an ablation have concomitant issues — they also need bypass surgery, mitral valve repair, aortic valve surgery, etc. But what if the patient just has symptoms of longstanding AFib? Do you perform a sternotomy just to do an ablation? That’s a pretty aggressive approach. Is there a less-invasive approach that can be effective with a limited risk profile and shorter recovery? That’s how interest in procedures like TT maze started. 

Describe the procedure. 

I make four incisions on the left and right that basically mirror each other. Two are 12 millimeters and two are 5 millimeters, so they’re really small. 

Then I open the pericardium, insert an endoscope and use radiofrequency to isolate the left side of the pulmonary veins. I take down the ligament of Marshall outside the heart, which in a small percentage of cases can be a source of persistent AFib, and I clip the left atrial appendage, where clots can form and which endocardial ablation doesn’t address. 

Then I create another lesion across the roof and floor of the atrium like I’m making a box around the left atrium. And on the right side I isolate the right pulmonary veins and complete the rest of the roof and floor. 

From a patient’s standpoint, it’s very well tolerated. Pain is pretty minimal and managed with regular medications. Most patients go home after spending two nights in the hospital. 

Who’s a good candidate? 

It’s not for everybody. It’s a bit more invasive than an endocardial approach, and for someone with paroxysmal atrial fibrillation, endocardial results are very good. 

But it’s good for patients who can’t tolerate their medications or who want to treat their left atrial appendage to decrease stroke risk. It’s especially good for a population that wants the best chance of staying out of longstanding persistent AFib. 

A lot of people with longstanding persistent AFib are miserable. They can’t sleep. They have anxiety. They can’t breathe when they’re in AFib. They can’t live their lives. 

That was true with my 71-year-old patient. She’d been on medication, had cardioversion and a few ablations — but she still couldn’t play with her grandkids and would go into AFib without warning. After the procedure, her heart was in normal sinus rhythm before she left the operating room. And that’s the point: If we can get people like her out of AFib, they can literally feel what it’s like to be healthy again. 

We’ve started the USC Heart Rhythm Disorders Center, and for clinicians who think their patients might benefit, referring them here never hurts. 

Why aren’t more clinicians aware of TT maze? 

It’s technically challenging and fewer people do it, but I think that comes down to awareness. Many internists, cardiologists and even electrophysiologists don’t know about this. I’ve actually had patients reach out to me because they’ve heard about it — but their doctors haven’t.  

I hope we can help more in our community learn about it, though, because it really has changed lives, and we’re really lucky to offer it here at Keck Medicine. We’ve performed it many times on patients. 

What should referring providers know about TT maze? 

Referrers should know that it’s not open-heart surgery. This is minimally invasive surgery.  

It is complex in the sense that you are working behind the heart, off bypass. One of the reasons why TT maze isn’t offered more widely is that surgeons must be willing to dedicate time to training in the procedure. You need someone who is technically able to do minimally invasive surgery in this area of the heart and be comfortable with it, which not a lot of people are. 

Another reason why TT maze isn’t offered more widely is that AFib treatment itself is often just not prioritized by providers. For some physicians, AFib is a secondary thought, which is a huge problem in the world of AFib. 

If you’re a referrer with a longstanding persistent AFib patient, you need a surgeon who believes this type of AFib is not good for people, that their lives are being ruined by it and that treating their AFib can help them. You absolutely want to go to someone who has expertise and is comfortable doing the procedure. You need that type of surgeon. 

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Kimberly J. Decker

Kimberly J. Decker is a freelance writer for Keck Medicine of USC.

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