A Prospective, Randomized Trial of a Self-expanding PTFE Stent Graft During SVG Intervention - Late Results - SYMBIOT III


This study evaluated the use of the Symbiot PTFE covered stent compared to bare metal control stent in the treatment of saphenous vein graft (SVG) stenosis.


The Symbiot PTFE covered stent would reduce diameter stentosis by at least 10% as measured by 8-month QCA.

Study Design

Study Design:

Patients Enrolled: 400

Patient Populations:

Up to 2 de novo or restenotic lesion in a sing SVG. Up to 2 stents could be implanted per lesion.

Primary Endpoints:

Percent Diameter stenosis

Secondary Endpoints:

  • Major adverse cardiac events (death, MI, TVR)
  • minimum lumen diameter
  • binary restenosis rate

    Drug/Procedures Used:

    SVG percutaneous intervetion using the Symbiot PTFE covered stent.

  • Principal Findings:

    Clinical follow-up was obtained at 8 months in 96% (n=384). Baseline characteristics were similar between the two groups. No significant differences in the rates of stent thrombosis were noted. No significant differences were noted in the rates of cardiac death or MI, but a trend toward increased rates of revascularization was noted in the Symbiot arm (23.5% v. 15.6%; p=0.05).

    8-month angiographic follow-up was obtained in 74% (n=278) patients. The 8-month binary restenosis rate showed an in-segment restenosis rate of 34.9% in the Symbiot arm and 23.3% in the control group (p=0.04). The primary endpoint of percent diameter stenosis was not significantly different when the Symbiot group (40.10 +/- 29.8%) compared to the control group (34.83 +/- 26.3%) patients (p=0.12).

    Lesion lengths were similar in the two groups (13.7 +/- 8.9 mm in bare metal stents v. 14.8 +/- 9.2% in the Symbiot stent group; p=0.20). The number of stents implanted in both groups was similar (1.2 +/- 0.5 bare metal stent v. 1.2 +/- 0.5 Symbiot; p=0.61). The total stent legth was significantly greater in the Symbiot group compared to control (26.2+/-13.6 v. 32.5+/-14.9; p<0.0013). The stent/lesion length ratio was similarly increased at 2.2 +/- 1.1 in the bare metal stent group and 2.7 +/- 1.6 in the Symbiot group; p=0.0013). No significant differences were noted in acute gain, late loss or loss index. When compared to control, the rate of proximal edge restensis was significantly greater at the proximal edge in the Symbiot group when compared to control (9.1% v. 1.8%; p=0.02).


    These data show that the Symbiot covered stent does not provide additional advantage in reducing the rate of angiographic restenosis when compared to control. The trend toward increased clinical and angiographic restenosis with the Symbiot stent may be related to the implantation of significantly longer stents when compared to control. Bare metal stents in SVG intervention performed well with low rates of revascularization at 8-month follow-up with TVR rate of 15.6%.


    Buchbinder, M. 8 -month Results from the Symbiot III Randomized SVG trial. Presented at Transcatheter Therapeutics 2004, Sept. 28. Washington, D.C.

    Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease

    Keywords: Polytetrafluoroethylene, Coronary Artery Disease, Follow-Up Studies, Metals, Thrombosis, Saphenous Vein, Constriction, Pathologic, Stents

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