The Gore Propaten vascular graft should be the synthetic graft of choice in lower-limb and dialysis access applications, according to clinical data reported by product manufacturer W.L. Gore & Associates (Flagstaff, Arizona) yesterday.
Ongoing Propaten vascular graft studies report primary patency rates as high as 79% at one year for below-knee bypasses, according to Gore. In comparison, prior to the Propaten vascular graft being available, non-heparin-bonded synthetic grafts achieved an average primary patency rate of 66% in below-knee bypass procedures at one year.
Gore said these "encouraging" interim results were presented to clinical audiences at the 2008 annual meeting for the Society of Vascular Surgery (SVS; Chicago) in San Diego.
"We are extremely pleased to see the positive study results of the Gore Propaten vascular graft in lower limb and dialysis access applications," said Deenu Kanjickal, PhD, product specialist for the product. "More than 15,000 Gore Propaten vascular grafts have been successfully implanted worldwide since commercial availability."
Gore says the Propaten surgical graft is the first of its kind on the market approved for the treatment of peripheral arterial disease (PAD) in the lower extremities. The graft is designed to address the gap in clinical performance between synthetic and vein grafts by bonding the anticoagulant drug heparin to the surface of the graft, with the potential to reduce thrombosis or clotting.
FDA cleared the device in 2006. At that time, Kanjickal called it a "game-changing technology" during a phone conversation with Medical Device Daily.
"I still think it is a game-changing product," Kanjickal told MDD yesterday. "At the time of the release we had a lot of data from Europe that spoke to the Propaten vascular graft. What has happened since then, especially with the SVS meeting, is that we have gotten data from the U.S. that validates the data we had from Europe."
At the SVS meeting in June, Richard Neville, MD, reported on an ongoing study at Georgetown University Medical Center (Washington). Sixty-two below-knee bypasses were implanted for critical limb ischemia (29% rest pain and 71% ulceration/gangrene) of which 77% were to tibial arteries, and the remaining 23% were bypasses to the below-knee popliteal artery. The primary patency at one, six, and 12 months for below-knee bypasses were 92%, 88.5% and 79% respectively by life table analysis, Gore said.
Michael Stoner, MD, of East Carolina University (Greenville, North Carolina), also reported on implants for above-knee and below-knee bypasses. Thirty-three above-knee and 12 below-knee Gore Propaten vascular grafts were implanted since February 2007.
The majority of the below-knee implants (83%) had a Rutherford classification of either four or five, were tobacco users (92%), had poor run-off (less than two) (83%) and half were diabetic. The one-year primary patency for the below-knee bypasses was reported to be 79%, the company said.
Most of the above-knee implants (97%) had a Rutherford classification of three, four or five, were tobacco users (64%) and had poor run-off (less than two) (64%). The one-year primary patency for the above-knee bypasses was reported to be 87%, Gore said. The above-knee Propaten vascular graft implants were then compared to 169 historical implants of non-heparin-bonded grafts at the same institution and were found to have a trend towards improved primary assisted patency for patients with poor run-off, according to the company.
William Jordan, MD, of the University of Alabama at Birmingham, reported on 44 implants, including 38 lower extremity (10 below-knee), two upper extremity, three visceral revascularization and one carotid; 39 of the 44 implants were patent at last follow-up out to one year, giving a gross patency of 89%, Gore said.
Ingemar Davidson, MD, PhD, at University of Texas Southwestern Medical Center (Dallas), presented interim results of a prospective, non-randomized study comparing the Gore Propaten vascular graft to a non-heparin-bonded graft in difficult patients for hemodialysis access application.
Sixty Propaten grafts were compared to 59 non-heparin-bonded grafts implanted since January 2007. The Propaten graft was generally preferred for difficult, high-risk patients, according to the company. At six months, the Propaten grafts were found to have significant improvement of 20% to 25% in the clot free and graft survival time as compared to the control group.
Kanjickal said that all of these studies are significant for Gore, but the studies that Neville and Davidson reported on are much further along than the others.
Gore also reported interim results about its Viabahn Endoprosthesis from a study for the management of superficial femoral artery occlusive disease. Karen McQuade, MD, of Baylor University Medical Center (Dallas), reported comparable 24-month patency rates between surgical above-knee femoropopliteal bypass and endoluminal bypass.
So far in the study of 100 treated limbs, the stent-graft group is showing primary patency of 82%, 73%, and 62% for six months, one year, and two years, respectively. For the same respective time points, primary patency for the surgical group, comprised of non-heparin-bonded, mostly polyester grafts, was 88%, 79%, and 65%. Similar secondary patency rates were seen at six months, one year, and two years (86%, 84%, and 73%, respectively, for stent-grafts versus 90%, 83%, and 75%, respectively, for the surgical grafts).
McQuade said the interim results of this study might support the use of stent-grafts as an alternative to surgery in the management of superficial femoral artery occlusive disease.
Gore reported FDA approval to market its Viabahn Endoprostheis for vascular bypass in the superficial femoral artery (SFA) last year). The Viabahn combines Gore's heparin surface treatment with the Viabahn Endoprosthesis for treatment of peripheral vascular disease in the SFA.
The device uses end-point covalent bonding to keep the heparin anchored to the endoprosthesis surface over time. The end-point surface attachment technology is designed to preserve the heparin bioactive sites such that they remain free to interact with the blood without being consumed.
The device is constructed with a reinforced, biocompatible, expanded polytetrafluorethylene liner attached to an external nitinol stent structure, with Gore saying that the Viabahn is the only device of its kind approved for treating PAD in the SFA.