Preclinical comparative assessment of a dedicated pediatric poly‐L‐lactic‐acid‐based bioresorbable scaffold with a low‐profile bare metal stent

Abstract

Background: Polymer-based bioresorbable scaffolds (PBBS) have been assessed for coronary revascularization with mixed outcomes. Few studies have targeted pediatric-specific scaffolds. We sought to assess safety, efficacy, and short-term performance of a dedicated drug-free PBBS pediatric scaffold compared to a standard low-profile bare metal stent (BMS) in central and peripheral arteries of weaned piglets. Methods: Forty-two devices (22 Elixir poly-L-lactic-acid-based pediatric bioresorbable scaffolds [BRS] [6 × 18 mm] and 20 control BMS Cook Formula 418 [6 × 20 mm]) were implanted in the descending aorta and pulmonary arteries (PAs) of 14 female Yucatan piglets. Quantitative measurements were collected on the day of device deployment and 30 and 90 days postimplantation to compare device patency and integrity. Results: The BRS has a comparable safety profile to the BMS in the acute setting. Late lumen loss (LLL) and percent diameter stenosis (%DS) were not significantly different between BRS and BMS in the PA at 30 days. LLL and %DS were greater for BRS versus BMS in the aorta at 30 days postimplantation (LLL difference: 0.96 ± 0.26; %DS difference: 16.15 ± 4.51; p < .05). At 90 days, %DS in the aortic BRS was less, and PA BRS LLL was also less than BMS. Histomorphometric data showed greater intimal proliferation and area stenosis in the BRS at all time points and in all vessels. Conclusions: A dedicated PBBS pediatric BRS has a favorable safety profile in the acute/subacute setting and demonstrates characteristics that are consistent with adult BRSs.

A word of caution: Early failure of Magmaris® bioresorbable stent after pulmonary artery stenting

“…4,9 These findings were alarming pushing the authors to raise significant concerns about the widespread applicability of RMS in infants with CHD. 6 Likewise in our case, we noticed an early complete loss of radial force of the Magmaris scaffold, suggesting stent failure in achieving its initial purpose to facilitate short-term bridging to surgery. The initial radial strength of the Magmaris ® was satisfactory as the stenosis was completely relieved.…”

“…Clinical experience with current coronary BRS and RMS in CHD lesions has been disappointing with restenosis rates suggesting a lack of appropriate radial strength 4,9 . These findings were alarming pushing the authors to raise significant concerns about the widespread applicability of RMS in infants with CHD 6 . Likewise in our case, we noticed an early complete loss of radial force of the Magmaris scaffold, suggesting stent failure in achieving its initial purpose to facilitate short‐term bridging to surgery.…”

“…Avoiding vessel growth restriction is extremely appealing in children where reintervention is inevitable to repair functional stenosis caused by a fixed stent in the setting of a growing vessel 4,5 . Despite the particular importance of BRS in children with CHD lesions, there is a paucity of pediatric‐specific scaffolds, due to the challenges of creating a mechanically stable large‐diameter scaffold coupled with the lack of financial incentive to do so 6 . The strength‐to‐weight ratio of metal is higher than that of polymers.…”

“…4,5 Despite the particular importance of BRS in children with CHD lesions, there is a paucity of pediatric-specific scaffolds, due to the challenges of creating a mechanically stable large-diameter scaffold coupled with the lack of financial incentive to do so. 6 The strength-to-weight ratio of metal is higher than that of polymers. Conventional metallic DES exhibit about fivefold higher tensile strength than RMS, and stents made of BRS require 50% thicker struts to match up with the current DES.…”

Preliminary testing and evaluation of the renata minima stent, an infant stent capable of achieving adult dimensions

“…Other potential therapies being evaluated for this unmet need in infants include biodegradable stents 17,18 and stents designed with predetermined breakage points to allow for expansion to larger diameters. 19 The advantages of biodegradable stents or scaffolds in this setting has been recognized for decades with a major potential advantage being the possibility of avoiding the need for future re-dilation as a child grows.…”