Angiographically occult in-stent protrusion detected by intravascular ultrasound during carotid artery stenting: a case report

BACKGROUND: Carotid artery stenting (CAS) is an established revascularization strategy for carotid stenosis, but periprocedural ischemic events remain a concern. In-stent protrusion, representing plaque protrusion and/or adherent thrombus, may be clinically relevant and can be underestimated by angiography alone. Intravascular ultrasound (IVUS) provides cross-sectional visualization of the stent lumen and may detect lesions not apparent on digital subtraction angiography. CASE PRESENTATION: We report the case of a 92-year-old man of Japanese ethnicity with symptomatic right internal carotid artery tandem stenoses treated with CAS under balloon protection. Completion angiography showed no intraluminal defect; however, IVUS demonstrated marked protrusion within the distal stent. Immediate rescue with an additional overlapping stent under re-occlusion eliminated the protrusion on repeat IVUS. The patient recovered without complications and was discharged home on postoperative day 4. CONCLUSIONS: This case highlights that IVUS may detect angiographically occult in-stent protrusion and may help guide prompt intraprocedural rescue and confirmation of lumen optimization.