Data on early vascular healing response of novel stent designs are scarce. In this randomized prospective trial, we sought to compare early neointimal coverage of cobalt-chromium-based titanium-nitride-oxide-coated bioactive stents (CoCr-BAS) versus platinum-chromium everolimus-eluting stents (PtCr-EES) at 2-month follow-up in patients with acute coronary syndrome (ACS). Forty patients with ACS were randomized to receive either CoCr-BAS (n = 19) or PtCr-EES (n = 21). Neointimal strut coverage and strut apposition were examined by optical coherence tomography; and coronary flow reserve (CFR), fractional flow reserve (FFR) and index of microcirculatory resistance (IMR) were assessed using a coronary pressure wire at 2 months. Two patients in the PtCr-EES underwent OCT out of the time frame of the study, and were excluded from analysis. At 63 ± 8 days, 302 cross-sections (3412 struts) were analysed in the CoCr-BAS group, and 324 cross-sections (3460 struts) in the PtCr-EES group. Median [IQR] neointimal thickness was 203 [108] µm and 42.2 [41] µm for CoCr-BAS and PtCr-EES, respectively (p < 0.001). Median [IQR] percentage of uncovered struts was 1.2 [2.8] % versus 11.3 [17.7] %, respectively (p < 0.001). Flow measurements were comparable between the two groups (p > 0.05 for all). CoCr-BAS showed earlier and more adequate neointimal coverage of struts at 2 months, compared with PtCr-EES, but with more neointimal hyperplasia. Functional healing as assessed by CFR, FFR, and IMR was similar between the two stent arms.
Keywords: Bioactive stent; Coronary flow reserve; Drug-eluting stent; Neointimal hyperplasia; Optical coherence tomography.