The use of bioresorbable scaffolds is the only complete solution for the superficial femoral artery, argued Andrew Holden, Auckland, New Zealand, in yesterday’s Peripheral Arterial Controversies session.
Presenting an update on the Stanza programme, Holden told delegates that the ideal treatment strategy for superficial femoral artery disease has been the source of much research, discussion and controversy. “An endovascular device should provide vessel support acutely to manage dissection and recoil, include an anti-restenosis strategy and preferably leave nothing behind when no longer needed. A bioresorbable drug-eluting scaffold potentially fulfils these requirements,” he explained.
The programme employed the Stanza platform (480 Biomedical)—a flexible, self-expanding stent design with full resorption in about 12 months. Holden summarised the development of the Stanza scaffold, the first part of which—the STANCE first-in-man trial—allowed “assessment of stent parameters such as precise positioning and deployment, excellent radial resistive force with minimal residual stenosis and satisfactory resorption.”
Two sub-studies in the STANCE trial allowed original validation of important imaging modalities by independent core laboratories. One sub-study analysed the accuracy of quantitative vessel analysis of magnetic resonance angiography (MRA) compared to the gold standard catheter angiography. A second sub-study compared cross sectional luminal area evaluation using MRA and optical coherence tomography (OCT). This comprehensive analysis, Holden explained, confirms MRA is “an effective method to assess the vessel lumen non-invasively after treatment with a bioresorbable scaffold.”
The study showed 100% scaffold delivery success, good scaffold apposition verified by optical coherence tomography (OCT) and angiography, and acute performance similar to metal stents. Holden noted that OCT is a vital tool in the assessment of bioresorbable scaffolds, as it allows investigators to identify scaffold encapsulation during healing and resorption. Using OCT Holden was also able to create 3D reconstructions of the vessel, allowing him to detect any scaffold fractures and show that at six months the scaffold demonstrated chronic strength to prevent vessel recoil.
The drug-eluting version of the Stanza platform is currently being assessed in the SPRINT clinical trial. Holden told attendees that the biggest challenge has been to define appropriate and extended drug release kinetics to deal with the inflammation associated with scaffold resorption. This has been achieved with the drug eluting version of Stanza. Currently, there is ongoing recruitment and evaluation in this trial, as well as several examples with medium-term follow-up.
In one such case study, pre-implant the patient had 88% stenosis, a figure which fell to just 2% residual stenosis following the implant. Similarly, in the second case that Holden presented, the pre-implant stenosis figure was 92%, falling to 0% following the implantation of Stanza. Both of these case studies were evaluated with MRA and OCT to confirm the outcomes.