ASD occluder used to close left atrial appendage

Susan Jeffrey

July 24, 2002

Wed, 24 Jul 2002 16:11:00

Bern, Switzerland - In an unorthodox procedure, Dr Bernhard Meier (Swiss Cardiovascular Center Bern, University Hospital Inselspital) has used a device designed to close atrial-septal defects (ASD) to block the left atrial appendage (LAA) in a patient with atrial fibrillation, heartwire has learned. Meier confirmed that he improvised use of the Amplatzer® ASD device (AGA Medical Corp, Golden Valley, MN) after the company that manufactures devices specifically for the LAA, Appriva Medical (Sunnyvale, CA), declined to allow him to use its device in that particular patient, deeming the case too high-risk.

Meier performed the procedure during live case demonstrations at the annual meeting of the Swiss Society of Cardiology (SSC).

This use of the Amplatzer ASD device, which already has FDA approval for ASD closure in the US, may introduce an element of competition for Appriva in this new applicationocclusion of LAA to prevent stroke in the setting of AFthe utility of which itself remains to be substantiated over the long term. If it proves beneficial, however, a potentially vast market awaitsit is estimated that 10% of those over 70 and 20% of those over 80 have AF.

The mother of invention

Appriva, under the direction of electrophysiologist Dr Michael Lesh, recently began developing a closure device for the LAA, based on evidence that more than 90% of stroke-causing thrombi in patients with AF originate there. Occlusion of the appendage, therefore, may obviate lifelong warfarin prophylaxis and improve the quality of life for these patients.

Lesh invented a device dubbed PLAATO® (for percutaneous left atrial appendage transcatheter occlusion) and, in collaboration with a growing number of centers, is investigating its use in this application. A feasibility study on 15 patients appeared in Circulation earlier this year, and since that time, 50 patients have received the PLAATO device, Lesh told heartwire . It recently received CE Mark approval on the basis of "100% success in closing the appendage and 0 major events," he said.

Meier's group in Bern was actually one of the institutions involved in the investigation of the PLAATO device. Meier, president of the SSC, is no stranger to new procedures. He was a fellow with the late Dr Andreas Grüntzig on the very first angioplasty procedure performed almost 25 years ago on September 16, 1977. However, he says the decision to use the Amplatzer device in this setting was not an impulsive one.

"Closing ASDs with this device. ..occasionally, you get into the left atrial appendage when you start to do the procedure, and then you have to pull it out of the appendage and put it into the right position," Meier told heartwire . "This had happened to me, and I knew that once you opened it in the LAA, it stuck there perfectly well and would have closed the appendage."

At the meeting, the patient planned for the live case demonstration was actually supposed to receive the Appriva device, he said. A few hours before the presentation, though, Appriva representatives examined the echo and concluded that clot was already residing in the appendage.

"Now I wasn't convinced," Meier said. "I couldn't prove that there weren't any, but it didn't look to me like there were any clots, so I kind of argued with them. I even showed them an echo of their own earlier series somewhere else, which they had published, which looked exactly the same."

 

Appriva's method is proved to be doable in 50 patients with a fairly complex procedure, and the Amplatzer technique is now proved in 1 patient, which is no proof whatsoever.

 

They still declined, so Meier, already feeling that the Amplatzer design would work, went ahead with the procedure. "I explained to the patient that we were doing an alternative technique that we had never done before, but that I knew technically would work," he said. He implanted it in a "very easy procedure, and there were no problems."

The patient was awake during implantation; unlike with the Appriva device, general anesthesia and intubation were not necessary, he added.

He is now collaborating with AGA Medical on developing a protocol to use this or possibly a slightly modified device in a new investigational series, Meier noted. "By far, neither of the methods is proved to be efficacious," he stressed. "Appriva's method is proved to be doable in 50 patients with a fairly complex procedure, and the Amplatzer technique is now proved in 1 patient, which is no proof whatsoever."

Rising tide raises all boatsbut paints all with the same brush?

Lesh told heartwire that although his company already has CE Mark approval in Europe, his group still feels strongly that the PLAATO device should be used on a protocol, and the current protocol calls for patients who have clots in the LAA not to undergo the procedure.

"We feel that until we know more, the risk of breaking a blood clot loose during the implantation procedure is potentially greater than implanting the device," he said. When clots are present, they are often transient, he added. They either organize or resolve, particularly with a short course of warfarin or heparin, making it possible to wait 1 or 2 months and then complete the procedure. "It's an elective procedure and there's no point in taking the risk."

Lesh notes that from their standpoint, any attention to this new procedure is positive. "This is a brand-new concept, and most people have not even thought of the idea of closing the appendage to prevent stroke. Clinical competition is actually a good thing, because a 'rising tide raises all boats,'" he added.

 

We're not afraid of competition, we just want to make sure the competition is going to treat patients properly so it doesn't damage the whole evolving field before it has a chance to get started.

 

"The problem is if you get people using a poor technology, and they get a lot of complications, the next levels of users won't distinguish between the PLAATO device versus somebody just using the Amplatzer," he said. "We're not afraid of competition, we just want to make sure the competition is going to treat patients properly so it doesn't damage the whole evolving field before it has a chance to get started."

While the hypothesis that obliterating the LAA should prevent stroke still needs to be proven scientifically, Lesh noted, "clearly it's a reasonable hypothesis to be tested, and the FDA has agreed, so we're going in that direction."

AGA pursuing LAA closure

Dr Kurt Amplatz, who designed the Amplatzer ASD devicealong with many others for various medical applicationsdeclined to comment on this single case. However, Frank Gougeon, executive vice president of AGA Medical, confirmed that the company would be going forward investigating the use of either this or another device for closure of the LAA.

Gougeon said they had already been investigating several of the company's devices in LAA closure in animals, without much success, possibly because the anatomy of the LAA may be too different or because the animals are in sinus rhythm, not AF.

"But then came that communication with Dr Meier and that case he did, and this is actually very good news for us, especially if a device that is already marketed for another application might be useful," Gougeon said.

 

Obviously we don't want to promote off-label use and we cannot do that, but at the same time, we have to look at the potential.

 

"Obviously we don't want to promote off-label use and we cannot do that, but at the same time, we have to look at the potential. If we were to start a project and go through a full new investigation, and then the clinical investigation, we're looking potentially at about 7 years before the device would even touch a market."

They plan to "fully support Dr Meier" in investigations going forward, to replicate this successful procedure, and to examine whether any of their other devices might be even more suitable in this application, Gougeon said.

"Let's wait and see"

Dr Franz R Eberli (University Hospital Zurich) cochaired the session and was present when Meier did the procedure.

"I was initially astounded he actually chose to take an ASD septal occluder to do that, but I must say, on second thought, it was a very good idea," Eberli told heartwire . "It was a snap; there were no problems technically whatsoever."

However, while the principle of the ASD occluder, a self-expanding device that holds itself at the neck of the LAA, seems feasible for this indication, Eberli did express some concern about whether this particular device is the ideal one for this procedure. ""In general, the ASD occluder could be a problem because it protrudes a little into the left atrium. If an oversized occluder would be chosen, it could touch the left atrial wall at the upper end," he said. Case reports have suggested that when the device touches the roof of the atrium, erosion can occur over time.

 

I was initially astounded he actually chose to take an ASD septal occluder to do that, but I must say actually, on second thought, it was a very good idea

 

Its larger size may also have implications for endothelialization of the device, he noted. However, these potential concerns could be addressed by imaging the patient over time, Eberli said, at which point it may be necessary to either modify the device or use something smaller.

Eberli, who worked with Meier for 5 years, said this type of innovation is typical of Meier. "When he solves problems in the cath lab, he has a very good understanding of the devices at hand and an excellent sense of what would work mechanically and what would not work," he said.

Eberli pointed out that this same type of competition among devices arose when ASDs were first closed percutaneously. "All of them made sense from the principle point of view, and then in the end 1 or 2 devices proved to be safe and clinically helpful," he said.

What has not been established in this indication, however, unlike the closure of the ASD, is the clinical utility of occlusion of the LAA. "The scientific discussion about the whole procedure is a totally different question that has to be solved," Eberli concluded.

Dr Horst Sievert (Cardiovascular Center of Bethanien Hospital, Frankfurt, Germany) was first author on the PLAATO paper that appeared in Circulation. He said he had heard about the procedure Meier had done but was not aware of the details.

"We have put occasionally Amplatzer devices into strange locations," Sievert told heartwire in an emailed reply. "They initially conformed to the anatomy very nicely but later on they came back to their original configuration. This may or may not cause problems (eg, hemopericardium) in the LAA. Let's wait and see."



Related links

[HeartWire > News; Apr 8, 2002]

[HeartWire > News; Dec 7, 2001]

[HeartWire > News; Sep 26, 2001]

[HeartWire > News; Jun 12, 2001]


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