OBJECTIVETo investigate the neointimal coverage at the very early phase after drug-eluting stent (DES) implantation using optical coherence tomography (OCT).

METHODSOCT examination was performed immediately after stent deployment and about one week post stenting in 12 patients with coronary artery disease to detect neointimal coverage and stent thrombus. Sirolimus eluting stent implantation was also performed in 5 healthy Chinese minipigs, OCT and histopathology examination were made one week later in these minipigs.

RESULTS(1) Twenty-nine DES were implanted in 12 patients. There was no major cardiovascular event post stenting. The mean time of follow-up was (7.7 ± 2.6) d, the mean percentage of stent coverage was (21.8 ± 17.7)%, and neointimal hyperplasia thickness was (42.9 ± 32.2) µm and the percentage of malapposition struts was (1.5 ± 3.0)%, respectively. Mural stent thrombus was found in 2 of the 12 patients (the percentage is 16.7%). (2) In the minipigs model, OCT evidenced that (43.2 ± 11.5)% struts were covered by neointima with a mean neointimal hyperplasia thickness of (24.0 ± 8.5) µm at one week. Histopathology examination illustrated that the neointima was mainly consisted of proteoglycan, inflammation cells, fibrin and organized thrombus at the very early phase after DES implantation, while endothelial cells were barely found on the neointima.

CONCLUSIONSNeointimal coverage is found as early as one week after DES implantation by OCT. The covered struts rate is very low and the main components of neointima are proteoglycan, inflammation cells, fibrin and organized thrombus. Re-endothelialization is rather poor at the very early phase post DES implantation.