Optical coherence tomography findings of balloon angioplasty/stenting for in-stent restenosis after carotid artery stenting

Objectives The optimal therapeutic methods for in-stent restenosis (ISR) after carotid artery stenting (CAS) remains controversial. This study aimed to use optical coherence tomography (OCT) to evaluate the in-stent architectures during endovascular angioplasty/stenting for ISR. Materials and Methods Six lesions of ISR after CAS were evaluated by OCT during endovascular angioplasty/stenting. Results In one lesion, the OCT system could not be crossed because of elongation distal to the ISR lesion. In five lesions, pre-procedural OCT clearly revealed neointimal hyperplasia or neoatherosclerosis. The mean in-stent area stenosis was 84%. After regular balloon angioplasty, tissue compression and dissection of various sizes and layers were detected. After balloon angioplasty (with a mean balloon size of 5.4 mm), the minimum lumen area (from 1.7 ± 0.6 to 11.4 ± 5.3 mm 2 , p < 0.01) and the minimum in-stent area (12.7 ± 2.6 to 21.8 ± 5.0 mm 2 , p < 0.01) showed a significant increase. Additional stent was placed in one lesion that developed into a flap by dissection after balloon angioplasty. In another lesion in which sufficient dilatation was not achieved by balloon angioplasty, a major stroke occurred by acute occlusion of the ISR lesion 10 months later. Conclusions OCT can detect the in-stent architecture of ISR lesions after balloon angioplasty and additional stent placement. However, which dissection should be treated by additional stent remain problematic.