Does optical coherence tomography identify arterial healing after stenting? An in vivo comparison with histology, in a rabbit carotid model

Objective: To verify whether optical coherence tomography (OCT) can accurately monitor the occurrence of arterial healing after stenting. Setting: Delayed stent endothelialisation may predispose to stent thrombosis. OCT is a high-resolution intravascular imaging technique that accurately identifies stent struts and arterial tissues. Design and interventions: Eight New Zealand white rabbits underwent the implantation of single bare metal stents (diameter 2-2.5 mm, length 8- 3 mm) in the right common carotid artery through the external carotid artery. After a median of 11 days (range 2-28), the stented arteries were visualised by OCT, with images acquired at a pull-back speed of 0.5 mm/sec. The rabbits were then euthanised, vessels were formalin-fixed and finally processed for histopathology. Results: We analysed 32 cross-sections from eight stented carotid arteries, for a total of 384 stent struts. OCT detected all of the stent struts in 30 of 32 crosssections (93.7%), and correctly identified the presence/ absence of tissue for every strut. Histological and OCT measurements of mean neointima thickness (0.135 (SD 0.079) mm and 0.145 (SD 0.085) mm, respectively, p= NS) were similar and closely related (r= 0.85, p < 0.001). Neointima area progressively increased with longer time intervals from stent deployment to sacrifice; histological and OCT measurements were similar for each time interval. The intra- observer and interobserver reproducibility of OCT neointima measurements were excellent (R-2= 0.90 and 0.88, respectively). Conclusions: OCT is a promising means for monitoring stent strut coverage and vessel wall healing in vivo, the relevance of which will become even more significant with the increasing use of drug-eluting stents.