In vitro mechanical behavior and in vivo healing response of a novel thin-strut ultrahigh molecular weight poly-L-lactic acid sirolimus-eluting bioresorbable coronary scaffold in normal swine Yanping Cheng a , Pawel Gasior a,c , Kamal Ramzipoor b , Chang Lee b , Jenn C. McGregor a , Gerard B. Conditt a , Thomas McAndrew d , Grzegorz L. Kaluza a , Juan F. Granada a,d, ⁎ a CRF-Skirball Center for Innovation, Orangeburg, NY, United States of America b Amaranth Medical, Inc., Mountain View, CA, United States of America c 3rd Department of Cardiology, Medical University of Silesia, Katowice, Poland d Cardiovascular Research Foundation, New York, NY, United States of America abstract article info Article history: Received 21 August 2018 Received in revised form 13 February 2019 Accepted 3 April 2019 Available online xxxx Background: New generation bioresorbable scaffolds (BRS) promise to improve the outcomes of current genera- tion BRS technologies by decreasing wall thickness while maintaining structural strength. This study aimed to compare the biomechanical behavior and vascular healing profile of a novel thin-walled (98 μm) sirolimus- eluting ultrahigh molecular weight BRS (Magnitude, Amaranth Medical) to the Absorb everolimus-eluting biore- sorbable vascular scaffold (Abbott Vascular). Methods and results: In vitro biomechanical testing showed lower number of fractures on accelerated cycle test- ing over time (at 21K cycles = 20.0 [19.0–21.0] in Absorb versus 0.0 [0.0–1.0] in Magnitude-BRS). Either Magni- tude (n = 43) or Absorb (n = 22) was implanted in 65 coronary segments of 22 swine. Scaffold strut's coverage was evaluated using serial optical coherence tomography (OCT) analysis. At 14 days, Magnitude-BRS demon- strated a higher percentage of embedded struts (97.7% [95.3, 100.0] compared to Absorb (57.2% [48.0, 76.0], p = 0.003) and lower percentage of uncovered struts (0.0% [0.0, 0.0] versus Absorb 5.5% [2.6, 7.7], p = 0.02). Also, it showed a lower percent late recoil (-1.02% [-4.11, 3.21] versus 4.42% [-1.10, 8.74], p = 0.04) at 28 days. Histopathology revealed comparable neointimal proliferation and vascular healing responses between two devices up to 180 days. Conclusion: A new generation thin walled (98-μm) Magnitude-BRS displayed a promising biomechanical behav- ior and strut healing profile compared to Absorb at the experimental level. This new generation BRS platform has the potential to improve the clinical outcomes shown by the current generation BRS. © 2019 Published by Elsevier B.V. Keywords: Bioresorbable scaffolds Optical coherence tomography Quantitative coronary angiography Histopathology 1. Introduction The Absorb everolimus-eluting bioresorbable vascular scaffold (BVS, Abbott Vascular) is the most widely studied poly-L-lactic acid (PLLA) based bioresorbable scaffold (BRS) [1,2]. This first generation BRS has an average strut thickness of 157-μm and relies on polymer crystallinity and a high vessel surface area to achieve stent-like mechanical proper- ties. Bench data suggests that this current generation BRS displays lim- ited over-expansion capabilities and structural integrity when exposed to high-loading conditions [3]. Recently published randomized con- trolled trials suggest that Absorb is associated with an increased risk of late scaffold thrombosis [4–6]. The late biomechanical failure of the device leading to intraluminal dismantling of thick-struts has been sug- gested as one of the potential mechanisms of scaffold thrombosis in humans [4]. Due to the inherent mechanical limitations of current generation PLLA, the successful development of thin-walled BRS has been challeng- ing. Previous studies have shown that a ultrahigh molecular weight amorphous PLLA-based BRS platform (Amaranth Medical, Mountain View, California) display elongation at break points 10 times higher compared to currently used PLLA and promise to improve the current technical limitations of clinically available BRS [7–9]. In this study, we aimed to evaluate 1) the in vitro mechanical behavior and 2) in vivo strut coverage and vascular healing profile of a novel generation thin- walled (98-μm) sirolimus-eluting amorphous PLLA-based BRS (Magni- tude, Amaranth Medical) as compared to Absorb BVS in a porcine coro- nary artery model. International Journal of Cardiology xxx (xxxx) xxx ⁎ Corresponding author at: CRF - Skirball Center for Innovation, Cardiovascular Research Foundation, 8 Corporate Dr., Orangeburg, NY 10962, United States of America. E-mail address: jgranada@crf.org (J.F. Granada). IJCA-27578; No of Pages 8 https://doi.org/10.1016/j.ijcard.2019.04.012 0167-5273/© 2019 Published by Elsevier B.V. Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard Please cite this article as: Y. Cheng, P. Gasior, K. Ramzipoor, et al., In vitro mechanical behavior and in vivo healing response of a novel thin-strut ultrahigh molecular ..., International Journal of Cardiology, https://doi.org/10.1016/j.ijcard.2019.04.012