ASD closure device erosions: Teacup tempest or tip of the iceberg?

July 28, 2011

Rochester, MN - A case report of a patient who suffered erosion of an Amplatzer septal-occluder device (St Jude Medical) six years after it was implanted, resulting in cardiac tamponade and necessitating emergency surgery to remove it, has ignited a debate about the safety of these devices, in particular with regard to erosion[1]. Dr Nathaniel W Taggart (Mayo Clinic, Rochester, MN) and colleagues discuss the case in the July 2011 issue of the Journal of Thoracic and Cardiovascular Surgery.

In an accompanying commentary[2], Dr Daniel J DiBardino (University of Michigan Medical School, Ann Arbor, MI) and Dr John E Mayer (Children's Hospital, Boston, MA) note that the longest previously reported interval between insertion and erosion of an Amplatzer device was three years, and they observe: "It seems that the complication pattern of this device is still being defined." They note that they published a review of adverse events with the Amplatzer device two years ago[3], which showed that adverse events with the device are increasing, although they acknowledge this "may simply reflect an increase in the number of devices placed." However, it is equally possible that the known events "are just the 'tip of the iceberg,' with a constant hazard function for erosion that exists over the lifetime of the patient."

One physician who uses the Amplatzer septal occluder frequently in his practice, Dr Robert J Sommer (Columbia University Medical Center), told heartwire that erosions are the one issue that make him pause before considering using the device. While he acknowledges that the risk of erosion is rare, the consequences are extremely serious, and there are no indicators that it is about to happen or any way of predicting who will suffer this fate, says Sommer. "This is a real phenomenon, it's not just anecdotal. If we knew how to predict this and we knew how to figure out what were the risk factors that would predispose someone to having this problem, then it would be an easy issue."

This is a real phenomenon, it's not just anecdotal.

But Dr William Hellenbrand (Children's Hospital of New York Presbyterian, NY), who has reviewed erosions with the Amplatzer septal occluder for the FDA, defends it, saying he has no doubts about the device as long as it is used for its intended indication, closure of atrial septal defects (ASDs). He points out that in this new case report of erosion after six years, the Amplatzer device was actually being used off-label, for patent foramen ovale (PFO) closure, "and that's not appropriate; I would not do that."

And St Jude Medical spokesperson Kristi Warner insisted to heart wire that there is no problem with this device: "To date, AGA Medical, now part of St Jude Medical, as well as an independent physician review board, have analyzed all reports of adverse events related to tissue erosion reported involving the Amplatzer septal occluder. The data from this analysis show that the product is a safe and reliable technology."

Two main devices available for ASD closure in US

ASD closure is often performed in children, but ASDs are also commonly found in adults who have remained undiagnosed their whole lives and who present in mid-life with symptoms such as shortness of breath or atrial arrhythmias. For many years, surgical closure of ASDs was the only option, but over the past 10 years, a number of devices for percutaneous closure have become available.

In the US, the two main devices in use are the Amplatzer septal occluder and the Helex septal occluder (Gore Medical). The two are made of the same material but differ in design, in that the Amplatzer device is a solid disk, whereas the Helex one is a helical coil; there have been no reports of erosions with the Helex device, say both Sommer and Hellenbrand, but this is suitable only for small to medium ASDs. For larger holes, "the only option is the Amplatzer device or surgery," says Hellenbrand. NMT Medical also made an ASD and PFO closure device, before declaring bankruptcy earlier this year.

There is also a third device in use in Europe, the Figulla Flex ASD occluder (Occlutech), which is similar in design to the Amplatzer one, and some other ones in development, Sommer notes.

Although approved only for ASD closure in the US, these septal-occluder devices are frequently and inappropriately used off-label for PFO closure, closure of ventricular septal defects (VSDs), aneurysms, and other defects, says Hellenbrand.

Estimates of precise rate of erosion difficult to come by

A precise estimate of the true rate of erosion is difficult to come by, and there is debate as to the cause of perforation/erosion. Sommer says in his years of using the Amplatzer septal-occluder device, he has implanted it in about 1000 patients and has had two erosions, one with a large device and one "with a very small device that I would never in a million years have expected." Although he acknowledges his estimate is a very unscientific one, based on his own experience he estimates the rate of erosion at one in 500 patients.

He says the views of doctors regarding ASD closure can vary greatly. "Some have the philosophy that if you have an ASD that can be closed in the cath lab, it should be done in the cath lab, and at the other end of the spectrum you have physicians who have responded to this [erosion] issue with uncertainty who say, 'I'm going to use the Helex device because it's noneroding, and if I can't use this because the hole is inappropriate, I'm going to send them to surgery,' and that's a little over the top, too."

Sommer says he has no qualms about implanting the Amplatzer device in adults, since he has an informed discussion with each patient about the risks. "I think it's fine for an adult to make their own decision. When I've met with an adult, I know they understand things, and I'm perfectly happy doing those cases. But sometimes it scares them off and they will go and have surgery." However, he says he is less comfortable about using this device in children, although he primarily works with adults.

Hellenbrand says he treats an equal number of children and adults, and "I don't differentiate between them because I'm talking to the patient or I'm talking to the parent. Parents are more than capable of making decisions for their children. To me, it's avoiding unnecessary open-heart surgery, but after I give people a balanced explanation, 5% to 10% will prefer surgery, and I think that's a reasonable decision on their part."

To me, it's avoiding unnecessary open-heart surgery.

He has recently performed a review of US data on erosions reported with the Amplatzer septal-occluder device when it is used for its intended indication, ASD closure, as reported to the FDA, the company, and from the literature. While he acknowledges that there may be cases that go unreported, "the incidence of erosions is at most 0.11%," he says. Hellenbrand presented these data to the FDA in February.

"I think if you look at the complication rates and the mortality data [with the Amplatzer device], it is still less than surgical mortality. With this information, I am now better placed to explain the erosion risk to the parents and the patients. The risks of having erosion are one in 1000. In children [erosion] usually happens early, and in adults it can happen later, but almost all of them happen within the first year."

In their review two years ago, DiBardino et al documented 51 known cardiac perforations, erosions, or ruptures with Amplatzer septal-occluder devices as reported to the US FDA between January 2002 and June 2007, from an estimated 18 000 implantations. Of these, 24 occurred more than 24 hours from placement, with eight happening within one to six months of the procedure, two at six months to one year, three at more than a year out, and seven unknown.

All agree on need for mandatory registry of every implant

One thing both Sommer and Hellenbrand agree on is the need for better documentation of adverse events such as erosion with these devices. "I would love to see the FDA do a mandatory registry of every implant, but they have not required it. I wish they would," says Hellenbrand.

And Bray Patrick-Lake (president and CEO of the PFO Research Foundation) says this is something that would benefit patients immensely. "No patient should have a device implanted in his or her heart without having data collected," she observes.

"Unless a treating physician takes the initiative to publish a case report on adverse events, patients never have a good understanding of the true incidence of complication rates," she told heart wire .

Sommer has consulting and advisory relationships with Coherex and Gore. Hellenbrand has consulted for AGA Medical, now part of St Jude, which markets the Amplatzer septal - occluder devices .




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