Impact of neointimal tissue characterization and heterogeneity of bare-metal stents and drug-eluting stents on the time course after stent implantation evaluated by integrated backscatter intravascular ultrasound

Pathological studies have suggested the different process of in-stent restenosis (ISR) of bare-metal stents (BMS) and drug-eluting stents (DES). Here, we evaluated the components of neointimal tissue using integrated backscatter intravascular ultrasound (IB-IVUS) and focused on the time course after stent implantation and tissue signal distribution. We evaluated 125 lesions of 125 patients who underwent target lesion revascularization for ISR (BMS: n = 73, DES: n = 52). Volume analysis of a 4-mm length centered on a minimum lumen area in every 1-mm cross-sectional area was performed. For IB-IVUS analysis, color-coded maps were constructed from the default setting based on the integrated backscatter (IB) values (middle-IB value, green: fibrous and low-IB value, blue: lipid pool). For the neointimal tissue volume, we evaluated the ratios of the green (%G) and blue (%B) areas. Tissue signal distribution (TD) was also obtained from the default setting based on IB values in each pixel of IB-IVUS imaging. We compared values of neointimal tissues measured by IB-IVUS between the DES and BMS and time course. The observed period was longer after BMS implantation than after DES implantation (BMS: 2545 days, DES: 1233 days, p