Intraprocedural Plaque Protrusion during Carotid Artery Stenting with a CASPER Stent: A Case Report

OBJECTIVE: Plaque protrusion (PP) during carotid artery stenting (CAS) is considered to be associated with periprocedural ischemic stroke. A new double-layer micromesh stent, the CASPER stent (CS), was approved for use in Japan in 2020. The expectation is that this micromesh stent system will reduce the risk of PP, but we report a case of PP during CAS despite the use of a CS. CASE PRESENTATION: An 87-year-old man presented with left hemiparesis. MRI showed right brain infarction and angiography showed right internal carotid artery stenosis with thrombus. Follow-up angiography after medical treatment showed that thrombus disappeared. We therefore performed CAS for right internal carotid artery stenosis with unstable plaque. CAS was performed under local anesthesia with Mo.Ma Ultra and FilterWire EZ protection using a CS placed to sufficiently cover the stenotic region. Conservative post-dilatation was then performed. Intravascular ultrasonography (IVUS) after post-dilatation showed the presence of PP. A second CS was then added using the stent-in-stent technique. No postoperative neurological abnormalities were found and the patient was discharged without postoperative complications. No stroke or restenosis has been observed as of 16 months after CAS. CONCLUSION: PP can occur even when CAS is performed using the CS for carotid artery stenosis with unstable plaque. The importance of checking for PP using IVUS is suggested.