Abstract 16601: Evaluation of Vascular Response After Balloon Angioplasty for In-Stent Restenosis Assessed by Optical Frequency Domain Imaging

Abstract

Background and aim: The optimal balloon angioplasty (BA) procedure for in-stent restenosis (ISR) was not established. The aim of this study was to investigate vascular response after BA in ISR lesions using optimal frequency domain imaging (OFDI). Methods and results: This study consisted of 22 ISR lesions that were treated with BA. OFDI analysis were performed for 10mm longitudinal ISR segment including minimum lumen area before and after BA, furthermore morphology of ISR neointimal tissue and volumetric measurements were assessed. We analyzed at 1mm interval cross-sectional OFDI images of lesions before BA, and at every slices per each lesion, the neointimal tissue was divided into 2 morphologic patterns: homogeneous pattern and non-homogeneous pattern. Then, the neointimal tissue morphological characteristics of each lesion was expressed according to “homogeneous ratio”, defined as the number of homogeneous pattern slices divide by a total of slices. In volumetric OFDI measurements, lumen gain rate was calculated as (lumen volume (LV) after BA - LV before BA) / LV before BA, stent expansion rate as (stent volume (SV) after BA - SV before BA) / SV before BA and neointimal volume (NV) reduction rate as (NV before BA -NV after BA) / NV before BA. There was no correlation between homogeneous ratio and lumen gain ratio. There was positive correlation between homogeneous ratio and stent expansion ratio, and there was negative correlation between homogeneous ratio and neointimal volume reduction ratio (figure). Conclusions: OFDI assessment is useful to understand the vascular response by BA for ISR lesions. The mechanism of lumen gain in BA procedure for ISR lesions with homogeneous tissue is mainly obtained by stent expansion, whereas for lesions with non-homogeneous tissue is by neointimal tissue compression.