New data from four studies released recently show promising results for stents and stent grafts in the superficial femoral artery.
Endovascular treatment of long lesions in the superficial femoral artery (SFA) still remain a challenge for physicians. Stenting has been shown to be superior to angioplasty in short lesions, but restenosis, re-occlusion and device fractures are some of the risks with stenting in longer segments.
The three-year follow-up from the RESILIENT trial shows that primary stenting delivered improvements in patency, freedom from secondary interventions and clinical success when compared to angioplasty. VIBRANT, and the more recent VIPER trial, show that the Viabahn endoprosthesis offers good patency in long lesions. And DURABILITY II demonstrated good initial results with a 200mm stent in superficial femoral artery/popliteal artery lesions.
Barry Katzen, medical director, Baptist Cardiac & Vascular Institute, Miami, USA, presented the three-year results of the RESILIENT trial at the VIVA conference in Las Vegas. He told delegates that the initial benefit of primary stent use with the LifeStent (Bard) was maintained at two and three years.
RESILIENT is a prospective, randomised, international trial that enrolled 206 patients in 24 centres in Europe and the USA. At 12 months, in claudicants with superficial femoral artery and/or proximal popliteal lesions ≤150mm, primary use of the LifeStent was superior to percutaneous transluminal angioplasty alone. Freedom from target lesion revascularisation was 87.3% with the LifeStent, and primary patency was 81.5% with the device, Katzen said.
He noted that, at 24 months, freedom from target lesion revascularisation was 77.8% in the LifeStent group and 41.8% with angioplasty (p<0.0001). At 36 months, the rate was 75.5% in LifeStent patients and remained at 41.8% in angioplasty patients (p<0.0001). The results showed a clinical success rate of 63.2% with the stent and 17.9% with angioplasty. Katzen also noted that the rates of major adverse events between the LifeStent and angioplasty groups are comparable, at 75.2%, in both groups.
“The LifeStent Vascular Stent System is intended to improve luminal diameter in the treatment of symptomatic de novo or restenotic lesions up to 240mm in length in the native superficial femoral artery and proximal popliteal artery with reference vessel diameters ranging from 4–6.5mm.” Katzen said, “The three-year data from the RESILIENT trial support durability and freedom from secondary interventions with LifeStent. These are the first outcomes to three years in a level one trial for stents in the superficial femoral artery,” he said.
“RESILIENT data have shown that primary stenting delivered improvements in patency, freedom from secondary interventions and clinical success. The stent also has a low fracture rate,” he said. “The 36-month data is very supportive of endovascular therapy as an approach, and specifically establishes the LifeStent as an effective way to provide durable clinical benefit. At three years, patients had only a 25% chance of needing revascularisation, a very acceptable clinical outcome.”
“Further study needs to be performed on patients with longer lesions that have been included in this and other superficial femoral artery trials, and perhaps even with stent to stent comparisons, as we have seen in the coronary circulation,” Katzen said.
The Bard’s Lifestent device is the only FDA-approved stent for the superficial femoral artery and proximal popliteal artery.
Gary M Ansel, Riverside Methodist Hospital, Columbus, USA, presented three-year results from the randomised, multicentre VIBRANT (Viabahn versus bare-nitinol stent) study showing that the Gore Viabahn endoprosthesis demonstrates durable results in the treatment of lesions >8cm in the superficial femoral artery. The trial assesses the performance of an older generation of the Viabahn device.
VIBRANT enrolled 148 patients (72 treated with non-heparin coated, non-contoured edge generation of the Gore Viabahn endoprosthesis and 76 with a bare nitinol stent) at 14 sites. The average lesion length was 18cm, with 59% of patients presenting with a chronic total occlusion. Duplex ultrasound follow-up occurred at one, six, 12, 24 and 36 months with additional plain film X-ray at the final three follow-up visits.
The outcomes of the Viabahn group versus the control group, respectively, include technical success (97 vs. 97%); primary patency (53 vs. 58%); freedom from target lesion revascularisation (73 vs. 69%); assisted primary patency (84 vs. 91%); and secondary patency (93 vs. 98%). Device occlusion was reported in nine patients in the Viabahn group compared to six patients in the bare-nitinol stent group. Focal-edge stenosis comprised 87% of failures in the Viabahn group whereas diffuse in-stent stenosis comprised 93% of bare-nitinol stent failures. There was one stent fracture in the 47 Gore Viabahn patients compared to 16 stent fractures in the 52 bare-nitinol stent patients (2 vs. 30.8%).
As a take-home message, Ansel said that VIBRANT included the toughest lesions ever studied in a controlled trial. He noted that stent fracture was still a concern, as fractures increase with time, and, with longer stents, more fractures tend to occur.
“VIBRANT shows durable three-year results with minimal re-interventions for long lesions. Eighty five per cent of patients required one intervention or no intervention to maintain patency over a three-year period, and there were no amputations. Stent grafts restenosed at the edge and bare nitinol stents restenosed diffusely.”
In a late-breaking trials session at VIVA, Richard Saxon, San Diego Cardiac and Vascular Institute, North County Radiology Medical Group in Oceanside, USA, principal investigator of the VIPER study, discussed the one-year results from the trial. The study evaluated the performance of the new Viabahn with heparin bioactive surface in treating long-segment superficial femoral artery lesions (>5cm in length). The single-arm, prospective study enrolled 119 patients at 12 sites.
Saxon said that the heparin surface may theoretically improve patency by decreasing all modes of stent graft failure, especially occlusion/edge stenosis in small vessels and devices. “In our experience, over two out of three of edge stenoses are at the proximal as opposed to the distal edge of the device. The contoured edge should improve wall apposition and decrease in-folding of the graft material proximally.”
The primary endpoints in VIPER were primary patency at one year and 30-day procedure-related major adverse events. There was one event (0.8%) leading to a surgical bypass after target lesion occlusion, but the device was markedly oversized in this case. At 12 months, duplex follow-up for 103 patients showed primary patency of 74%, assisted patency of 87% and secondary patency of 92%. The average lesion length was 19cm.
Saxon told delegates that the VIPER results support the conclusion that the Viabahn device with contoured edge and heparin bioactive surface exhibits improved patency in superficial femoral artery lesions relative to the previous device. He added that patency is independent of lesion length, with >20cm lesions showing similar patency to lesions 5–20cm. Importantly, when the instructions for use are followed, primary patency is remarkably high (>85%). He also noted that the 5mm device patency is equivalent to other sizes. “The results with the 5mm device are substantially improved with the heparin coating compared to previous results.”
“There are multiple options for superficial femoral artery intervention. If we treat the correct subset of patients with this newer stent graft, patency will be excellent, and re-interventions will be low. This is an excellent technique for long lesions, but we need adequate landing zones. We do need to measure, using quantitative angiography or intravascular ultrasould. Your ‘eyeball’ is just not good enough.”
He told Vascular News: “I believe the 12-month results of VIPER as well as the results of many of the other trials presented recently give the interventionalist a lot more information on how to achieve better, more durable results in the superficial femoral artery. It is now incumbent on us as physicians to take the time to develop an understanding of how to best treat different subsets of patients differently. It is no longer a ‘dealer’s choice’ situation in which there is no data, so you can argue for whatever technique you feel like using on a given day. Now we have to take the time to analyse the patient’s anatomy carefully and treat the patient based on the data available.”
In order to improve the clinical results with endovascular approach in the superficial femoral artery, physicians must follow the instruction for use, Saxon said.
“If one uses quantitative means to size a vessel such as intravascular ultrasound or quantitative angiography and is careful to not oversize the endoprosthesis too much (<20% according to the instruction for use, I think ideally <10%) then, according to VIPER, one gets results that are over 20% better than if you do not follow these guidelines. The 5mm diameter results were far better than before, so people should no longer try to put 6mm devices in vessels <5mm in diameter, as their results will be worse. The industry can spend a lot of money to improve their devices enough to get 20% better patency at a year, all we interventionalists need to do is to be more rigorous about our technique. I think that is the key challenge now. We need to educate everyone on these results and more rigorously tailor our approach to the superficial femoral artery based on the anatomy we are treating.”