Stent strut coverage of titanium-nitride-oxide coated stent compared to paclitaxel-eluting stent in acute myocardial infarction: TITAX-OCT study

Drug-eluting stents (DES) have reduced the rate of restenosis but recent studies have raised concern over the risk of late stent thrombosis (LST). Incomplete stent endothelialization and delayed vascular healing have been associated with LST. The titanium-nitride-oxide coated bio-active stent (BAS) has shown promising results in patients with acute coronary syndromes, but there is little long-term optical coherence tomography (OCT) data comparing BAS with DES. The TITAX-AMI trial is a prospective, randomized, multicenter trial comparing BAS to paclitaxel-eluting stent (PES) in 425 patients with acute myocardial infarction. A total of 18 patients (9 per group) with no major cardiac events during follow-up, were enrolled in this substudy >36 months (mean 47 months) after stent implantation. Quantitative coronary angiography was performed and stent strut endothelialization and vascular healing were assessed with OCT. The binary stent strut coverage was significantly higher in the BAS group compared with the PES group (99.6 vs. 89.2%, p < 0.001) and there were less malapposed struts in the BAS group (0.2 vs. 13.8%, respectively, p < 0.001). The neointimal hyperplasia (NIH) thickness (266 ± 166 vs. 126 μm ± 126 μm, p < 0.001) and percentage of NIH area (26.2 vs. 7.6%, p < 0.001) were greater in the BAS group than in the PES group. Late incomplete endothelialization was not uncommon after PES implantation. Stents in the BAS group were completely endothelialized. This difference may contribute to the more common LST after PES implantation in the TITAX-AMI trial.