Evaluation of neointimal morphology of lesions with or without in-stent restenosis: An optical coherence tomography study

Background: Characterization of neointimal tissue is essential to understand the pathophysiology of in-stent restenosis (ISR) after drug-eluting stent (DES) implantation. Using optical coherence tomography (OCT), we compared the morphologic characteristics of in-stent neointimal tissue from 33 ISR lesions with those of 192 non-ISR lesions after DES implantation. Hypothesis: We hypothesized that the morphologic characteristics of in-stent neointimal tissue from ISR lesions were different from those of non-ISR lesions after DES implantation. Methods: The DES were coated with sirolimus (n=52), paclitaxel (n=57), zotarolimus (n=84), or everolimus (n=32). In-stent restenosis was defined as ≥50% diameter stenosis at the follow-up angiogram. Lesions with ≥10% neointimal burden ([neointima area × 100]/[stent area]), as determined by OCT, were included in this study. A follow-up OCT (mean follow-up duration, 12.0 ± 10.5 mo) was performed in 209 patients with 225 lesions (ISR lesions, n=33; non-ISR lesions, n=192). Qualitative OCT was used to assess tissue structure, backscatter, visible microvessels, and presence of intraluminal material. Results: The following characteristics were more common in ISR lesions than in non-ISR lesions: heterogeneous or layered tissues (78.8% vs 22.9%, P<0.001), low backscatter (60.6% vs 20.8%, P<0.001), and microvessels (48.5% vs 5.7%, P<0.001). The independent predictors for heterogeneous or layered neointimal tissues were increased neointima burden (odds ratio [OR]: 1.218, 95% confidence interval [CI]: 1.096-1.354, P<0.001), lumen area (OR: 4.672, 95% CI: 1.371-15.914, P = 0.014), and hypertension (OR: 0.415, 95% CI: 0.186-0.926, P = 0.032). Conclusions: This follow-up OCT study demonstrated that morphologic characteristics of neointimal tissues of ISR lesions differ from those of non-ISR lesions.