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The aim of this study was to compare the strut coverage of the XIENCE stent with that of the BuMA Supreme sirolimus-eluting cobalt-chromium stent, which has a shorter drug elution, on optical coherence tomography (OCT) one or two months after implantation. Methods and results:The PIONEER-II OCT trial was a multicentre, two-arm randomised trial, which comprised two cohorts: cohort-1 underwent an OCT imaging one month after coronary intervention (BuMA: 16 patients with 18 lesions, XIENCE: 15 patients with 17 lesions), whereas cohort-2 underwent OCT at two months (BuMA: 21 patients with 21 lesions, XIENCE: 23 patients with 28 lesions). The primary hypotheses were non-inferiority of the BuMA stent to the XIENCE stent in percent strut coverage at one month (cohort-1) or two months (cohort-2). In cohort-1, the BuMA stent was non-inferior to the XIENCE stent in terms of the strut coverage (83.8±10.4% for BuMA vs. 73.0±17.5% for XIENCE, p for noninferiority <0.001), and was also significantly higher than the XIENCE (p for superiority 0.037). In cohort-2, the BuMA stent was non-inferior to the XIENCE stent in OCT strut coverage (80.3±18.3% vs. 73.3±21.3%, p for noninferiority 0.006, p for superiority 0.24). Healing scores showed better healing in the BuMA stent in cohort-1 (32.36±21.59 vs. 54.88±34.65, p=0.027), whereas there was comparable healing between the BuMA and XIENCE stents in cohort-2 (39.86±37.77 vs. 53.75±42.84, p=0.25). Conclusions:The BuMA Supreme had a faster coverage than the XIENCE at one month, presumably due to faster and shorter sirolimus elution. The difference in tissue coverage became less evident at two months. ClinicalTrials.gov Identifier: NCT02747329.

Background: Second-generation drug eluting stents (DES) have shown a high efficacy in terms of restenosis prevention, like first-generation DES, with reduced rates of stent thrombosis, especially late stent thrombosis. The suggested mechanism for this superiority is a better morphological and functional healing response. The objective of this study is to compare the efficacy and safety results of 2 different, first and second-generation, DES in a swine model of normal coronary arteries. Methods: In 9 domestic juvenile swine (25Ϯ3 kg), one stent per coronary artery was implanted with an intended stent-to-artery ratioՆ1.1. We used 9 bare metal stents (BMS), 9 permanent-polymer paclitaxel eluting stents (PES) and 9 biodegradable-polymer biolimus eluting stents (BES). Quantitative coronary angiography was performed after 28 days to assess the in-stent % stenosis and the endothelium-dependent vasomotor response of the distal vessel (Acetylcholine 10-6M). We performed morphometric analyses of the in-stent % area stenosis and the endothelialization rate (haematoxylin-eosin stain, extent of luminal surface coverage with endothelial cells) at 3 levels of each stent sample. The eNOSϩ endothelialization index measures the proportion of the whole luminal surface covered by eNOSϩ endothelial cells. Results: All the stents were implanted as per-protocol, with a final stent:artery ratio 1.17Ϯ0.15. No baseline differences were observed between groups. The Table shows the restenosis and the functional healing parameters analyzed in each group.