Medical Device Daily Washington Editor
WASHINGTON – On Thursday, the FDA approved a new device that is intended to prevent ruptures of descending thoracic aneurysms by making a new path for blood flow.
The Gore TAG Endoprosthesis System from W. L. Gore & Associates (Flagstaff, Arizona) is the first endovascular grafting system approved in the U.S. to treat thoracic aortic aneurysm (TAA).
"This is the culmination of years of work," Elizabeth Hoff, Gore's global marketing leader for aortic, told Medical Device Daily.
The device – in an early version, and now as an updated second-generation device – has been available in overseas markets since 1998, Hoff said. And the company has been in clinical trials designed for U.S. approval since that time.
Aneurysms occur when a section of the aorta – the main artery that carries blood in the body – weakens and bulges outward like a balloon. If the aneurysm ruptures, the patient is at high risk for death due to internal bleeding. TAA is generally believed to be significantly under-diagnosed, because three out of four individuals with aneurysms are asymptomatic, Gore said.
TAA traditionally has been treated with highly invasive open surgery that requires the surgeon to make a large incision in the patient's chest in order to sew a synthetic graft in place, which prevents the aneurysm from rupturing. An open surgical procedure is particularly risky for older patients who may suffer from additional medical conditions such as diabetes or hypertension.
The company says its TAG device is a significantly less-invasive endovascular strategy. The device is inserted through a small incision in the patient's groin, and a catheter delivery system is guided into position through the patient's arteries under fluoroscopy.
Once in position, a reinforced ePTFE- (expanded polytetrafluoroethylene) covered, self-expanding nitinol stent is secured inside the weakened section of the thoracic aorta. This creates a new path for blood flow and relines the aorta. The stent-graft excludes the diseased segment from the pressure of blood circulation, thereby reducing the risk of a rupture.
Data from the pivotal trial showed that Gore TAG patients after 30 days had less than one-fourth the rate of resultant paraplegia (3% vs. 14%) and one-third fewer strokes (11% vs. 33%) than the patients in the control group treated with the traditional surgical option.
Studies also showed that hospital stays were shortened on average from 10 days to three days. The Gore TAG device group experienced a 66% reduction in aneurysm-related death, and had no aneurysm ruptures after two years. Patients also were able to return to normal activity in less time than those undergoing open surgery (30 days vs. 78 days).
The FDA approved the system based on review of two clinical studies of the device's safety and effectiveness. The studies involved about 200 patients and showed that aneurysm-related deaths were lower in those who had received the endoprosthesis than in the surgical control group.
As a condition of approval, the FDA is asking Gore to conduct post-approval studies to ensure that when the endovascular grafting system is used in the large general population, its safety and effectiveness will be comparable to the clinical trials, and to evaluate the long-term clinical performance of the device.
Hoff said that no devices would be sold until physicians have gone through a training program to learn how to properly implant the device.
"Already this morning, I have had about 15 calls from doctors saying they wanted to place an order," Hoff told MDD. "First they need to go to a course and follow the very strict FDA-approved training guidelines."
The training program includes a two-day course and a participation in a specific amount of training cases.
Going forward, Hoff said the company will begin working on multiple product iterations, but said that was "a little farther out."
She also said Gore hopes to begin clinical trials this summer on the current product iteration to gather data for an indication involving high-risk applications.
Richard Cambria, MD, professor of surgery at Harvard Medical School and chief of the division of vascular and endovascular surgery at Massachusetts General Hospital (both Boston) testified during the January FDA panel meeting to consider Gore's premarket approval application.
Cambria called Gore's technology and similar devices "the single significant advance in the treatment of thoracic aortic pathology in our lifetimes."
At the same meeting, Michael Tuchek, DO, a thoracic surgeon with the Loyola University Health System (Chicago), who has performed similar procedures for the same indication using the AneuRx Stent Graft System developed by Medtronic (Minneapolis), also had good things to say about the device.
"I am not here to torpedo their efforts; I am here to applaud them and think they have done a great job with this trial," Tuchek said, calling the technology "nothing short of astounding."
He told the panelists: "This is critically needed technology and far and away better than the open operation. We need an endovascular alternative to treat these patients and I implore you to let this device be approved."
The panel members raised questions about trial design – in particular the design of the control group – and the amount of data reported by the company.
In the end, the recommendations to the FDA seemed to come down to individual panel members' belief that having the Gore device on the market would ultimately benefit patients and outweighed the safety risk.
According to the American Medical Association (Chicago), 15,000 people die annually as a result of TAA. In addition, 5% to 10% of those who die of sudden death (roughly 200,000 annually) are estimated to have died as a result of TAA, which brings the number of deaths up to an estimated 30,000 each year. That is about the same number of people who die every year of breast or prostate cancer.