The surprises in optical coherence tomography (OCT) findings in patients presenting with in-stent restenosis: the road less travelled

Type of funding sources: None.

Morphological features of neointimal tissue play a pivotal role in the pathophysiology of In-Stent Restenosis (ISR) after percutaneous coronary intervention, hence understanding these features and patterns is crucial.

The present study was designed to qualitatively and quantitatively assess neointimal characteristics of lesions using OCT in patients presenting with ISR.

This was a single-center, prospective, observational study performed between 1st August 2020 and 30th December 2021 at a tertiary-care center in India. Patients diagnosed with stable angina and acute coronary syndrome with post-procedural angiographically documented restenosis (>50%) were included. Qualitative and quantitative assessment of neointimal hyperplasia patterns was performed using OCT.

A total of 34 patients with ISR were studied. Neointimal hyperplasia was classified as (i) homogenous group (n=18) and (ii) non-homogenous group (n=16). As many as 14 (77.8%) diabetics belonged to the homogenous group. Predominant plaque characteristics such as neoatherosclerosis, cholesterol crystals, and calcium were documented in 14 (77.8%), 12 (66.7%), and 11 (61.1%) patients in the homogenous group and in 10 (62.5%), 10 (62.5%), and 9 (56.2%) patients in the non-homogenous group, respectively. Unexpanded stent struts were identified in 11 (61.1%) and 11 (68.8%) patients in the homogenous and non-homogenous groups, respectively. Mean strut thickness was 93.73 ± 31.03 µm and 83.54 ± 18.0 µm, ISR was 72.50 ± 15.93% and 65.37 ± 21.69%, the neointimal thickness was 588.06 ± 167.82 mm and 666.25 ± 218.05 mm, and neointimal hyperplasia was 54.54 ± 11.23% and 59.26 ± 8.86% in the homogenous and non-homogenous groups, respectively.

Neoatherosclerosis and stent underexpansion was predominantly observed in our study, which was in contrast to most of the existing literature [1,2,3], and only diabetes was found to be significantly associated with homogenous neointimal hyperplasia, irrespective of the generation of the stent.