In the largest randomised trial for treatment of superficial femoral artery disease patients with a drug-eluting stent, the Zilver PTX paclitaxel-eluting stent (Cook Medical) showed a low stent fracture and presented better outcomes than angioplasty and angioplasty plus bare metal stent in patients with symptomatic femoropopliteal disease.
The results of the ZILVER PTX study were presented as a late breaking trial by Michael Dake, Stanford University, Stanford, USA, at the Transcatheter Cardiovascular Therapeutics (TCT) 2010 congress (21–25 September 2010), in Washington, USA.
The study enrolled 479 patients at 55 sites in the United States, Japan and Europe. The primary safety endpoint is 12-month event-free survival (freedom from death, amputation, target lesion revascularisation, or worsening Rutherford score (by two classes or to class 5 or 6). Primary effectiveness endpoint is 12-month primary patency.
At 12 months, Dake told TCT delegates, the patency rate was 83.1% with Zilver PTX and 67% with angioplasty plus bare metal stent. Also, at 12 months, the patency rate was 89.9% with Zilver PTX and 73% with the bare metal stent in a head-to-head comparison of provisional stenting, demonstrating that the drug effect was significant. “That is a 63% reduction with the drug-eluting stent compared to the bare metal stent,” said Dake.
Safety endpoints in the trial were also met. The ZILVER PTX trial will follow patients for up to five years. There will now be considerable interest in whether Zilver PTX will continue to show improved patency at 24 months.
STRIDES and SIROCCO
Previous superficial femoral artery drug-eluting stent trials failed to show sustained benefit. In STRIDES, the Dynalink E (Abbott Vascular) showed clinical benefit with improvement in Rutherford-Becker clinical category in 80% of patients after 12 months and there were no observed stent fractures after 12 months. However, the improved patency rate was not sustained at 12 months.
SIROCCO II (Sirolimus coated Cordis Smart nitinol self-expandable stent for the treatment of obstructive superficial femoral artery disease) confirmed the short-term efficacy of the slower release formulation identified in SIROCCO I. It found good outcomes in the bare Smart stent arm of the trial with an overall six-month angiographic pooled restenosis rate of 11.6% (n=43) and an 18-month rate of 22.2% (n=45). However, slower eluting data pooled from SIROCCO I and II resulted in an early statistically significant difference in the primary endpoint (mean stent diameter), showed that this advantage was lost by 18 months.
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