Results with the fully self-expanding Stanza bioresorbable scaffold in the superficial femoral artery were presented by Andrew Holden, Auckland, New Zealand, at the VEITHsymposium. He also presented initial results with the new, drug-eluting version of the device. In the presentation, Holden, who is director of Interventional Services at Auckland City Hospital and associate professor of Radiology at Auckland University School of Medicine, noted that the advantages of a bioresorbable scaffold for treatment of superficial femoral artery disease include allowing vessel scaffolding while leaving nothing behind, eliminating chronic vessel irritation due to stenting, not having future interventions encumbered by a permanent stent, and also allowing non-invasive imaging with MR angiography.
“The Stanza scaffold is a composite structure of PLGA fibres with an elastomer coating. It is a typical flexible, strong self-expanding design with radial resistive force similar to nitinol stents, and fully resorbs in 12–15 months. A drug-eluting version of the Stanza device entered the clinic this month [November 2013],” he said.
In animal models, optical coherence tomography (OCT) demonstrated that by three months there is full interval lining of the scaffold struts, and there is progressive resorption of the scaffold so that by 15 months the scaffold struts have completely resorbed. In addition, in vivo 3D micro-CT showed that at one month and three months the integrity of the scaffold is preserved, without microfractures through the entire healing period.
The STANCE feasibility trial was a first-in-man trial using the Stanza platform. It was a single-arm, multicentre study and included de novo lesions in the superficial femoral artery (Rutherford Becker 2–3 claudicant patients). Three scaffold sizes—7x40mm, 7x80mm, and 7x100mm—were used. Doppler ultrasound and clinical evaluation were performed through the study, with angiography at six or 12 months, and OCT/intravascular ultrasound (IVUS) and MR angiography substudies.
Holden told delegates: “The scaffold performed as we hoped, like a strong, self-expanding stent would perform. Delivery success was 100% and procedural success was 96%. It also performed maintaining a blood lumen very well as we hoped it would do. Post procedure OCT also demonstrated good scaffold apposition.”
On a 3D OCT analysis, Holden said, there was no evidence of strut fracture.
“The first cohort of 25 patients achieved excellent acute performance with 100% scaffold delivery success and good scaffold apposition verified by OCT and angiography. There was no scaffold migration, fracturing or scaffold distal embolisation. However, on follow-up we did see some vessel recoil so we knew we needed to make a scaffold that was stronger for a longer period of time,” Holden commented.
For that reason, a Stanza version 1.1, with greater radial stiffness, was then developed and on a new cohort of patients (cohort B). “The new version has a considerably stronger scaffold; in fact, it was considerably stronger acutely than many of the self-expanding stents that we currently use. We did still expect that there would be neointimal hyperplasia, but the stronger version of the scaffold maintained an excellent diameter,” Holden said.
Holden told delegates that a Stanza drug-eluting resorbable scaffold has been developed. It features a thin layer, 2–3µm thick with paclitaxel/polymer coating, with a controlled drug release. The device is being evaluated in the SPRINT trial, a prospective, single-arm, multicentre study, enrolling patients with similar characteristics of those in the STANCE study. The first case with the device, performed in October, was successful, with a good blood lumen. Holden added that the scaffold produces no susceptibility in the blood lumen, no signal loss, so MR “can visualise the scaffold extremely well”.
In conclusion, Holden said, “we demonstrated feasibility of a fully self-expanding, bioresorbable scaffold with successful deployment of all scaffolds without any in-hospital major adverse events, with acute residual performance comparable to metallic stents, good scaffold apposition and no fracture as verified by OCT. Moreover, the second generation scaffold demonstrates improved resistance to chronic vessel recoil. And I am excited to announce that the Stanza drug-eluting resorbable scaffold has entered the clinic.”