Preclinical evaluation of the degradation kinetics of third- generation resorbable magnesium scaffolds

Background: The novel sirolimus-eluting resorbable scaffold DREAMS 3G was designed as a third -gen-eration development of its predecessor, the Magmaris scaffold. Aims: This preclinical study aimed to examine the qualitative and temporal course of the degradation of the DREAMS 3G relative to the Magmaris scaffold. Methods: Forty-nine DREAMS 3G and 24 Magmaris scaffolds were implanted into 48 mini swine for degradation kinetics analysis. Another DREAMS 3G was implanted into one mini swine for crystallinity analysis of the degradation end product after 730 days. Degradation kinetics were determined at 28, 90, 120, 180, and 365 days.Results: Discontinuity density in DREAMS 3G was significantly lower than that in Magmaris scaf-folds for the follow-up timepoints of 90 and 120 days. Planimetric analysis indicated 99.6% back-bone degradation for DREAMS 3G at 12 months. Compared to the Magmaris scaffold, individual strut degradation in DREAMS 3G showed less variability and the remaining backbone core was more homo-geneous. The degradation end product of DREAMS 3G manifested as calcium phosphate with a minor share of aluminium phosphate.Conclusions: DREAMS 3G showed almost complete degradation after one year, with amorphous calcium and aluminium phosphate as the end products of degradation. Despite its thinner struts, scaffold disconti-nuity was significantly lower in the DREAMS 3G than in the Magmaris scaffold, likely providing a longer scaffolding time.