Objectives To assess the frequency of peri-strut low intensity area (PLIA) in polymeric and nonpolymeric drug-eluting stents by optical coherence tomography (OCT) in porcine model, to analyse the pathological changes in PLIA.
Setting Previous intravascular ultrasound studies showed that black holes were more commonly seen in sirolimus-eluting stent restenosis. Similar phenomenon (peri-strut low intensity area) was also frequently detected by OCT in DES follow-up. However, it is still largely unknown what triggers this uncommon response. Design and interventions: A total of 18 stents (BMS, n=6; polymer-free PES [PF-PES], n=6 and polymer-based SES [PB-SES], n=6) were implanted in six minipigs and OCT was performed at 28 days after stenting. Stented arteries were harvested after terminal OCT imaging for pathological analysis. PLIA was defined as a region around stent struts with a homogenous lower intensity appearance than surrounding tissue on OCT images without significant signal attenuation behind the area.
Results At 28 days, PLIA was more frequently observed around the PBSES struts compared with PFPES and BMS struts (75% vs 33% vs 12%, respectively, p<0.001). Both in DES and BMS group, stents with PLIA showed significantly greater neointimal thickness than stents without PLIA (0.55±0.23 mm vs 0.13±0.08 mm, p<0.001). Histological results showed the existence of fibrin deposition and small amount of inflammatory cells at the site of PLIA.
Conclusions PBSES showed a higher incidence of PLIA compared with BMS and PFPES. PLIA may be related to fibrin deposition and vessel chronic inflammatory response to stent.