360KARJALAINEN PP et al. Circulation JournalOfficial Journal of the Japanese Circulation Society http://www. j-circ.or.jp inflammatory and hypersensitivity reaction leading to incomplete endothelialization following DES implantation. Localized hypersensitivity reaction has been demonstrated in the vessel wall at autopsy, and in thrombus aspirates, from patients with very late ST following first-generation DES. 4,5 Newer generation DES have thinner stent platforms, biodegradable/biocompatible polymers and rapid drug elution compared to first-generation devices. The frequency of uncovered struts was reported lower with biodegradable polymer biolimecent reports suggest a paradigm shift in the occurrence of stent thrombosis (ST) as evidenced by lower event rates in patients treated with newer generation drugeluting stents (DES) compared to bare metal stents (BMS) or first-generation DES. 1 Incomplete neointimal coverage over stent struts has been suggested as a potential substrate for late ST in histopathological studies, 2 as well as in an observational case-control setting using optical coherence tomography (OCT) in vivo. Background: Patients at high bleeding risk would benefit from a shorter dual antiplatelet therapy after PCI. Compared to first-generation devices, the design of newer generation drug-eluting stents may facilitate more rapid anatomical and functional healing of stented vessel based on thinner stent platforms, biodegradable/biocompatible polymers and rapid drug elution.

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.

TTE is a feasible and reliable method for the assessment of CFR and vasodilator dysfunction after DES implantation. Values obtained with this method successfully find abnormal CFR confirmed with the invasive thermodilution method.