Aims: 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, pfor noninferiority <0.001), and was also significantly higher than the XIENCE (pfor 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%, pfor noninferiority 0.006, pfor 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.