Covered Stent Shows Promise in Treating Long SFA Lesions

Download this article's Factoid (PDF & PPT for Gold Subscribers)

A heparin-bonded covered stent may hold some advantages over  bare-metal stents (BMS) for treatment of long diffuse superficial femoropopliteal artery (SFA) disease, according to data published online July 10, 2013, ahead of print in the Journal of the American College of Cardiology. The covered stent showed a trend toward better patency at 12 months, although there were no differences in walking distance or clinically driven target lesion revascularization (TLR) rates between stent types.

For the prospective, multicenter VIASTAR trial, investigators led by Johannes Lammer, MD, of Vienna General Hospital (Vienna, Austria), randomized 141 patients with complex femoropopliteal lesions to the heparin-bonded, covered Viabahn stent ( WL Gore, Flagstaff, AZ; n = 72) or BMS( n = 69).

The Viabahn device consists of a self-expanding nitinol stent encapsulated in expanded polytetrafluoroethylene (ePTFE), a Teflon-like substance, with heparin bonded to the surface.

Clinical, Patency Benefits Seen

The mean lesion length was 19.0 ± 6.3 cm in the covered stent group and 17.3 ± 6.6 cm in the BMS group (P = 0.13). Procedural success was achieved in all but 1 patient (malposition of a BMS). The rate of serious procedural adverse events within 30 days was low and equivalent in both groups at 1.4%. There were no instances of death, MI, or limb amputation. At discharge ankle-brachial index (ABI) was significantly improved in both groups (from 0.58 ± 0.17 to 0.93 ± 0.18 in the covered stent group and from 0.58 ± 0.16 to 0.96 ± 0.14 in the BMS group).

In the intention-to-treat analysis, 12-month primary patency (primary efficacy endpoint) showed a trend in favor of the covered endoprosthesis. However, this analysis was flawed by major protocol deviations in 8.5% of patients (6 in each group). When the protocol violations were excluded and the results were analyzed on a per-protocol basis (n = 129), there was an advantage for primary patency in the covered stent group (table 1).

Table 1. Primary Patency at 12 Months

ITT, intention to treat; TPP, treatment per protocol. ^a Log-rank P.

At 12 months, a multiple Cox proportional hazards model indicated that risk of TLR for BMS vs. the covered stent by treatment group and length of treated segment was 2.71 (95% CI 1.36 to 5.39). Freedom from TLR was similar for the covered stent and BMS groups (84.6% and 77.0%; P = 0.37). ABI was higher in the covered stent group compared with the BMS group (0.94 ± 0.23 vs. 0.85 ± 0.23; P < 0.05).

Improvement by at least1 Rutherford category was reported in 84.0% of patients in both groups. In addition, by 12 months, average walking distance improved over baseline to a similar degree in the covered stent and BMS groups (from 136.3 m to 785.8 m and from 115.1 m to 565.9 m, respectively).

In ITT analysis, for lesions ≥ 20 cm, the 12-month primary patency rate was higher with the covered stent compared with BMS (71.3% vs. 36.8%; P = 0.01). The secondary patency rate after TLR and bypass surgery also trended higher in the covered stent group (89.9% vs. 75.2%; log-rank P = 0.058).

Reasonable Option in Understudied, Challenging Subset

In an editorial accompanying the study, John R. Laird, MD, and Ehrin J. Armstrong, MD, both of the University of California, Davis Medical Center (Sacramento, CA), congratulate the authors for shedding light on a “challenging subset of patients that remains understudied,” The results indicate that the “heparin-bonded covered stent is a reasonable treatment strategy for patients with long-segment femoropopliteal occlusive disease,” they write.

Drs. Laird and Armstrong say the findings confirm that the durability of femoropopliteal stenting with BMS is inversely related to lesion length, while patency following implantation of the covered stent graft appears to be independent of lesion length.

“[T]here is less certainty about the optimal treatment of short or medium length lesions,” they write, adding, “Newer bare metal stents, drug eluting stents, drug coated balloons, and atherectomy devices have all shown promise for these shorter lesions.”

Another lingering question, they say, is whether a DES can provide comparable results to an ePTFE-covered stent in these longer lesions. “Perhaps covering a stent with an anti-restenotic drug is as effective as an ePTFE barrier,” they suggest.

Clarifying, Stratifying SFA Still Challenging

Michael D. Dake, MD, of Stanford University School of Medicine (Stanford, CA), told TCTMD in a telephone interview that the findings suggest “incremental benefits” for the novel covered stent in longer lesions, but cautioned that the protocol violations make it difficult to draw firm conclusions about the true clinical value of the device.

Dr. Dake said while Viabahn appears to be “in the same ballpark” as the polymer-free paclitaxel-eluting Zilver PTX stent (Cook Medical, Bloomington, IN), which was approved late last year by the United States Food and Drug Administration for treatment of superficial femoropopliteal artery disease, the Zilver trial excluded lesions greater than 14 cm.

“I think in the future we will see some head-to-head comparisons [of these and other stents] because we are seeing more and more technology that is considered promising, or at least is showing positive signals in areas like these long lesions,” he said. “We are clearly moving away from simply grouping lesions as SFA and moving toward teasing out and stratifying these lesions and the best ways to treat them.”

Study Details

All patients had:

• Symptomatic PAD (Rutherford-Becker clinical stage 2 to 5)
• De novo arteriosclerotic stenosis or occlusion of the SFA and proximal popliteal artery 10 to35 cm in lengthPatent or successfully treated iliac artery inflow
• Outflow of at least 1 tibial artery.

All patients received 5,000 IU heparin during the procedure. After treatment, patients were prescribed 100 mg aspirin daily for life and 75 mg clopidogrel daily for at least 6 months. Most patients began clopidogrel 1 or 2 days before the index procedure; for those who did not, a loading dose of 300 mg was given prior to or during the intervention.

Types of BMS used included:

• Life-Stent (BARD Peripheral Vascular, Tempe, AZ)
• Protégé EverFlex (ev3, Plymouth, MN)
• SMARTControl (Cordis/Johnson & Johnson, Warren, MA)

1. Lammer J, Zeller T, Hausegger KA, et al. Heparin-bonded covered stents versus bare metal stents for complex femoro-popliteal artery lesions: The randomized VIASTAR trial. J Am Coll Cardiol. 2013;Epub ahead of print.
2. Laird JR, Armstrong EJ. Stents for femoropopliteal disease: Are some things better covered up? J Am Coll Cardiol. 2013;Epub ahead of print.

Related Stories:

• Novel ‘3D’ Stent Improves Clinical Status in Femoropopliteal Disease Patients
• Zilver PTX 2-Year Results Published: Superior Safety, Efficacy vs. Angioplasty Sustained
• Zilver Stent Seen as Welcome Addition to PAD Armamentarium