Andrew Holden, associate professor of Radiology, Auckland City Hospital, Auckland, New Zealand, presented data on the developments in bioresorbable technology at the Charing Cross International Symposium (5–8 April, London, UK). He said that, as drug-eluting balloon data are limited to short and intermediate length lesions, bioresorbable stents or scaffolds are an “exciting prospect” for the future.
“The long and mobile femoropopliteal arterial segment is a challenging environment for endovascular intervention; for more complex lesions a scaffold is often required to prevent residual stenosis and flow-limiting dissection. An anti-restenosis strategy is also important, particularly in claudicants where long-term patency is vital,” he noted.
“Drug-eluting balloons are highly promising but have only been studied for any duration in relatively short lesions. Drug-eluting stents have shown satisfactory patencies in intermediate length lesions but suffer the problems of a permanent self-expanding metallic implant.” In order to address this problem with drug-eluting stents, Holden said for many years bioresorbable stents have been eagerly awaited in the superficial femoral artery.
“A bioresorbable stent may provide a scaffold to optimise the acute result after angioplasty without the long-term irritation of a self-expanding stent. Such a scaffold must withstand the hostile environment of the superficial femoral artery, provide mechanical support and integrity through vessel healing, remain biocompatible through resorption and facilitate drug delivery,” he said.
Three bioresorbable stents have recently been studied in the superficial femoral artery. The Abbott Esprit 1 trial used a balloon expandable poly L-lactic acid scaffold in iliac and femoral arterial lesions ≤50mm in length that could be treated by a single 6.0mmx58mm device. The study reported excellent procedural success. Although lesion length was short (mean 35.7mm), the patency data and improvement in Rutherford-Becker status at one year was very encouraging, Holden said.
He also noted that the 480 Biomedical Stanza stent has been studied in the STANCE trial. This flexible, self-expanding stent is a poly lactic-co-glycolic acid and bioresorbable elastomer composite and fully resorbs in 12–15 months. Acute performance and subsequent stent strut encapsulation and resorption has been evaluated with optical coherence tomography (OCT). This study reported excellent procedural success and acute stent performance, treating longer lesions (up to 90mm), according to Holden.
Holden explained that late lumen loss seen in the first cohort of patients was due to a combination of vessel recoil and neointimal hyperplasia. The device was modified in a second patient cohort with minimal vessel recoil. A paclitaxel, drug-eluting version of the scaffold has recently entered the clinic in the SPRINT trial, he added.
He also reported that the Igaki-Tamai bioresorbable scaffold ( Remedy, Kyoto Medical) has been used in the superficial femoral artery in a 30 patient cohort. Acute procedural results were very good, as in the STANCE trial, Holden noted.
“Binary restenosis rates at 12 months were unacceptably high and further modifications are planned. Small clinician initiated trials using coronary bioresorbable stents in the tibial arteries are being performed but meaningful results are not yet available,” Holden commented.
“There has been considerable progress with bioresorbable stents in the superficial femoral artery. The technology is not yet ready for routine clinical practice but that exciting prospect should not be far away,” Holden concluded.