Maurice Buchbinder, MD, from the Foundation for Cardiovascular Medicine in La Jolla, Calif. presented that the Symbiot Self-Expanding PTFE Covered Nitinol Stent (Boston Scientific) failed to show a benefit compared to bare-metal stenting in the reduction of distal embolization and restenosis following saphenous vein graft stenting.
The SYMBIOT-III trial was designed to show the superiority of the Symbiot stent for the treatment of saphenous vein graft disease over the use of bare-metal stent controls, with a primary endpoint a 10% reduction in diameter stenosis at eight-month follow-up.
Patients who received the bare-metal stent had slightly lower rates of major adverse cardiac events and stent thrombosis that did not reach statistical significance. Patients who received the Symbiot stent achieved slightly better levels of target vessel revascularization and target lesion revascularization, but these differences were not statistically significant.
There were minimal differences at eight-month follow-up in reference vessel diameter and minimal lumen diameter. Symbiot performed slightly better in terms of acute gain, late loss and loss index.
In terms of the primary endpoint - in-stent diameter stenosis at eight months - the Symbiot stent performed slightly better. When expanding to the analysis segment, the bare-metal stent achieved slightly better outcomes. The Symbiot stent reduced in-stent and analysis segment restenosis, but not by a statistically significant margin. The addition of the PTFE barrier also failed to reduce intimal hyperplasia.
Inclusion criteria were liberal, which provided for a high-risk population. Patients had up to two de novo or restenotic lesions in a single saphenous vein graft and up to two stents per target lesion. Angiographic criteria called for lesion length <41 mm, reference vessel diameter >3.5 mm and <5.5 mm and total stent length <51 mm.
In the trial, 400 patients were stratified to receive GP IIb/IIIa antagonists and embolic protection, and were then randomized to receive a bare-metal stent or the Symbiot stent. Patients underwent 30-day clinical follow-up, eight-month angiographic follow-up and 12-month clinical follow-up. The patient population was notable only for the large number of patients with diabetes (38% of control; 41% of Symbiot).